,transcriber's notes3 ,the text of this book has been preserved as in the original1 apart from a few obvious misspellings4 ,corrected misspellings and redundancies include the following3 comparsion -- comparison dining -- during clamly -- calmly atronomer -- astronomer oi -- of the -- 7deleted7 a -- 7deleted7 ,in this digital version1 paired underscores denote italicised text4 ,footnotes have been positioned below the relevant paragraphs4 ,the text contains symbols that will not necessarily display correctly with all viewing devices1 and one symbol 7for the ,full ,moon7 cannot be replicated digitally4 ,it is represented in this text by an open circle4 ,for best viewing1 the device's character encoding should be set to ,unicode 7,,utf-#h71 and a ,unicode font selected such as ,arial ,unicode ,,ms1 ,deja,vu1 ,segoe ,,ui ,symbol or ,free,serif4 ,illustration3 ,a ,,whirling ,,spiral ,,nebula1 ,,typical ,,of ,,that ,,from ,,which ,,the ,,sun ,,and ,,planets ,,were ,,probably ,,evolved ,in the process of evolution the dense center becomes the controlling sun and the smaller spots of condensation form the planets4 ,this particular nebula lies just under the end of the handle of the ,big ,dipper4 ,it was photographed at ,mt4 ,wilson ,observatory4 ,,the ,,ways ,,of ,,the ,,planets ,,by ,,martha ,,evans ,,martin1 ,a4,m4 ,,author ,,of 8,,the ,,friendly ,,stars0 ,illustration ,,new ,,york ,,and ,,london ,,harper ,,brothers ,,publishers ,,mcmxii ,,copyright1 #aiab1 ,,by ,,harper ,,brothers ,,printed ,,in ,,the ,,united ,,states ,,of ,,america ,,published ,,october1 #aiab ,,contents ,,chap4 ,,page ,i4 ,,on ,,making ,,acquaintance ,,with ,,the ,,planets #a ,,ii4 ,,our ,,relation ,,to ,,the ,,planets #aa ,,iii4 ,,what ,,the ,,planets ,,are1 ,,and ,,what ,,they ,,appear ,,to ,,be #ag ,,iv4 ,,the ,,origin ,,of ,,the ,,planets #bf ,v4 ,,the ,,seven ,,great ,,planets #ch ,,vi4 ,,the ,,movements ,,of ,,the ,,planets #df ,,vii4 ,,how ,,the ,,inferior ,,planets ,,seem ,,to ,,move #ef ,,viii4 ,,how ,,the ,,superior ,,planets ,,seem ,,to ,,move #fe ,,ix4 ,,the ,,path ,,of ,,the ,,planets #ga ,x4 ,,mercury--,,when ,,and ,,where ,,to ,,find ,,mercury--,,distance ,,and ,,brightness--,,mercury',s ,,size ,,and ,,the ,,consequences ,,of ,,it-- ,,what ,,the ,,sun ,,does ,,for ,,mercury--,,transits #ic ,,xi4 ,,venus--,,when ,,and ,,where ,,to ,,see ,,venus--,,distance ,,and ,,brilliancy--,,venus',s ,,likeness ,,to ,,the ,,earth--,,atmosphere1 ,,day ,,and ,,night1 ,,and ,,seasons--,,transits #abb ,,xii4 ,,mars--,,how ,,to ,,identify ,,mars--,,when ,,and ,,where ,,mars ,,may ,,be ,,seen--,,size1 ,,atmosphere1 ,,and ,,temperature--,,distance ,,and ,,brilliancy--,,day ,,and ,,night1 ,,and ,,seasons--,,surface ,,aspects--,,satellites #aea ,,xiii4 ,,jupiter--,,place ,,in ,,the ,,sky--,,distance1 ,,light1 ,,and ,,heat-- ,,day ,,and ,,night1 ,,seasons1 ,,and ,,atmosphere--,,surface ,,features--,,system ,,of ,,satellites #ahc ,,xiv4 ,,saturn--,,around ,,one ,,circuit ,,of ,,the ,,skies ,,with ,,saturn-- ,,distance ,,and ,,size--,,surface ,,aspects ,,and ,,constitution-- ,,day ,,and ,,night--,,the ,,rings ,,and ,,moons ,,of ,,saturn--,,seasons #bjf ,,xv4 ,,uranus #bbe ,,xvi4 ,,neptune #bcd ,,xvii4 ,,the ,,little ,,planets1 ,,or ,,the ,,asteroids #bdd ,,xviii4 ,,conclusion #beh ,,symbols ,,used ,,in ,,almanacs #bfg ,,index #bfi ,,illustrations ,a ,,whirling ,,spiral ,,nebula1 ,,typical ,,of ,,that ,,from ,,which ,,the ,,sun ,,and ,,planets ,,were ,,probably ,,evolved ,frontispiece ,,map ,,showing ,,the ,,constellations ,,of ,,the ,,zodiac ,,and ,,the ,,line ,,of ,,the ,,ecliptic ,,running ,,through ,,them ,facing p4 #gf ,,the ,,lovely ,,crescent ,,that ,,venus ,,shows ,,when ,,to ,,our ,,view ,,she ,,is ,,at ,,her ,,greatest ,,brilliancy #acf ,,relative ,,apparent ,,size ,,of ,,venus ,,at ,,different ,,phases ,,of ,,illumination ,page #acg ,,the ,,two ,,phases ,,of ,,mars ,facing p4 #aeb ,,mars3 ,,difference ,,in ,,its ,,apparent ,,size ,,at ,,its ,,nearest1 ,,middle1 ,,and ,,farthest ,,distance ,,from ,,the ,,earth ,page #afi ,,jupiter1 ,,the ,,mammoth ,,member ,,of ,,the ,,solar ,,family-- ,,larger ,,than ,,all ,,the ,,other ,,planets ,,put ,,together ,facing p4 #ahd ,,saturn ,,and ,,its ,,rings #bbj ,,the ,,ways ,,of ,,the ,,planets ,i ,,on ,,making ,,acquaintance ,,with ,,the ,,planets ,it is sought in the following pages to give a simple account of what may now be said to be known of the character of the planets1 and to describe with as little technicality as possible their movements and aspects and relations4 ,an endeavor is made to impart concerning each one of them not1 surely1 profound learning1 but just a good1 every-day1 practical notion1 so that the mere name will call up a definite object1 with its own attributes1 appearance1 and behavior1 entirely distinct from any other planet or from any other object in the skies4 ,an endeavor is made also to so simplify and direct the observation that any one1 after a little practice1 will know almost without hesitation1 on seeing a planet in the sky1 that it is a planet1 and not a fixed star1 and exactly what planet it is4 ,the situation and aspect of it will then as quickly and clearly pronounce it to be the individual planet that it is as the sight of a person of one's acquaintance proclaims him to be that person1 and no other4 ,the very name of ,venus1 for example1 and still more the sight of ,venus1 will call up a conception of ,venus1 with the particular atmosphere and light and movements and wanderings which make her what she is4 ,on looking at her the observer will at once know why she occupies the special position in the sky in which he sees her1 why she is not so bright as she was when she was last in view1 or is so much brighter than she was then1 about how long she is likely to remain where she is1 and when she goes what will become of her4 ,for far off and truly mysterious as the planets are1 it still is with them as with most other objects in nature3 a very little knowledge of their aspects and their ways begets a sense about them that makes the most casual observation of them interesting and1 as far as it goes1 intelligent4 ,the slightest glance at them betrays some shape1 or position1 or light1 or other quality1 which at once makes recognition of them unmistakable4 ,they disclose themselves oftentimes1 one can scarcely say how1 just as persons with whom we are intimate do by some half-caught outline1 motion1 or posture2 or just as the trees do to an observer who knows1 for example1 an oak-tree from an elm1 whether they are covered with their own peculiar verdure1 or whether they stand with bare branches stretched out and colored in their own peculiar way4 ,this instant recognition of the planets is1 of course1 not to be had by simply reading about them4 ,such practical familiarity with them is attained only by seeking them out over and over again and looking at them with attention1 with eagerness1 and with all one's faculty4 ,with them1 as with other natural objects1 it requires observation truly to know them4 ,but then1 observation1 when one gets a little started in it1 is a great deal more interesting1 a great deal more absorbing1 than any reading about them can ever be4 ,it is also a very easy thing to begin1 for1 after all1 it is not much more than looking and then looking again4 ,in doing this one can hardly tell just when an object ceases to be strange1 and then becomes familiar1 and finally is so much a part of every-day knowledge that one knows it at a glance4 ,but this is what happens in the case of any natural object when we observe it often and with true attention4 ,in the case of the planets1 if one is interested at all1 every stage in the cultivation of such an acquaintance is full of pleasure4 ,even to one who regards them only as a part of the general aspect of the sky1 they are the most beautiful objects in it and always the first to attract special attention4 ,nine times out of ten1 when any one asks what a certain star is1 it proves to be one of the planets4 ,when one of them is visible a person can hardly glance at the heavens without noticing it1 even if he does not stop to think about it4 ,but if he does stop to think about it and notices that it is far larger than any star he has noted before1 that it hangs low in the western sky early in the evening1 and shines with a brilliant silvery light1 and if he then learns that it is ,venus1 will he not always have a pleasant thrill of recognition when he again sees such a star in such a position and knows it as ,venus1 among the planets as surpassing in beauty as the goddess of that name was among the immortals8 ,or1 if in the east1 at the same time in the evening1 he sees a brilliant1 solid-looking1 unblinking star shining with a white light1 but pinkish white1 not silvery1 and finds it to be ,jupiter1 will not such a star in such a situation be to him ever after a pleasant acquaintance that he can call by name8 ,not that ,jupiter and ,venus are always in these positions1 or shine in just this way at all times4 ,these are their places and aspects at certain times1 frequently recurring1 and at such times always unmistakably distinguish them4 ,it is1 then1 merely the matter of a little more and yet a little more observation1 in order to come to know any one of the visible planets in all its varying aspects and situations4 ,of course1 at the start some guidance is necessary1 but only a little2 and that little1 if it is of the right sort1 should not be irksome4 ,to provide such guidance is one of the aims of this book4 ,that is1 indeed1 its main aim4 ,but in addition to what1 as a help in observation1 it may find to say regarding the appearance and movements of the planets1 it will endeavor to give also ample information concerning their character and constitution4 ,it is hoped that this may be done without weighting the narrative with figures1 though some of the peculiarities of the planets must be expressed by means of numbers4 ,certainly no mathematical problems will be presented4 ,but it will be profitable to remember that every one of the intimate things we know about the planets has come to us through the long and laborious mathematical work of astronomers4 ,to them we owe the extinguishable debt that we owe to all special workers who put us in possession of the facts that interpret life to us4 ,for the astrology and poetry and romance of the planets one must go elsewhere4 ,nearly every book on the subject of the planets--and there are many of them--has some information about these things2 and properly1 too1 for every genuine emotion and every real fancy has its value4 ,but neither curious lore of the planets nor the sentiment and emotion they have produced in others is what the author of this book is striving to set forth4 ,it is something much more vital than this4 ,what we wish to contemplate here are the plain facts1 the knowledge of which enlivens and enriches one's mind and nature4 ,if the contemplation of them kindles one's fancy or excites one's emotions1 these results at least will not be second-hand4 ,if the bare facts1 simply and plainly told1 and the view of the planets themselves as they wander through their courses in the sky1 do not awaken one's understanding and imagination1 no amount of poetry or romance that other people have built up around the planets will arouse anything more than a factitious interest in them4 ,it is when our own faculties are at work and our own fancy plays over a subject that we become genuinely and lastingly interested in it4 ,the facts themselves are in the main quite simple1 and will not be given here as anything else than that4 ,they have been fairly wrested from that mysterious thing called space by the mighty power of mind and unceasing labor4 ,our knowledge of them is due to long nights of watching and long days of calculating2 to long and careful testing and considering of theories1 only to find that something else must be tried2 to courage to begin all over again1 to sudden inspirations1 and sometimes to those lucky discoveries that seem almost like miracles4 ,the subject of the planets has in some respects a greater interest even than that of the stars1 because we know1 after all1 more about them4 ,we sometimes have a feeling1 though1 that we know more of the stars1 although the stars are so much farther off4 ,why we have this feeling it is easy to explain4 ,knowing them to be so far removed from us1 we really approach the stars with a different expectation4 ,the few things that we have learned about them have in themselves such a magnitude that it makes them seem a greater body of knowledge than they truly are4 ,the stars are indeed so far away1 and what we know of them has to be expressed in such large terms1 that the mind does not demand in that information the minute exactness that it seeks for in the case of nearer objects4 ,in the case of the stars1 we seek mainly to know their distances1 the direction of their motions1 the speed with which they travel1 and their probable connection with each other4 ,the fact that in computing the distance of a single star1 many trillions of miles away1 the result may be a little less than exact does not keep us from learning what ones are sufficiently near for their distances to be measured at all and what ones are immeasurably remote4 ,whether they travel at the rate of exactly three or three hundred miles a second1 we can learn that some are traveling at somewhat the same rate of speed as our sun travels1 and some incredibly faster2 that certain groups are going in one direction and certain groups in another2 that some are approaching us and some are receding from us4 ,and thus we can classify them and learn the significance of these facts1 and1 little by little1 gain a definite understanding of the construction and meaning of the entire universe4 ,their very remoteness gives a certain compactness to the information we have about the stars1 by making it necessary to generalize more than we would if they were near enough to yield more details2 and we are in a way satisfied with this more general sort of knowledge of them4 ,but the very fact of our knowing so much about the planets extends our curiosity concerning them and makes us feel that we ought to know more4 ,the mind is provoked into more minute speculations about them1 and we demand more exactness of information and knowledge of a more specific or intimate sort than would satisfy us in regard to the stars4 ,atmosphere1 habitability1 exact size1 seasons1 and day and night1 are the kind of things we most seek to know in reference to the planets4 ,these are such definite things that conclusions concerning them are subject to close criticism1 and differences of opinion in regard to them thus sometimes occur which tend to give one a more or less confused notion of what is really known4 ,as a matter of fact1 our information about the planets is much fuller than our knowledge of the stars1 as we would naturally expect it to be4 ,much of what we seek to know about the stars has long been common knowledge about the planets4 ,,ii ,,our ,,relation ,,to ,,the ,,planets ,to know about the planets is to know about ourselves4 ,the earth is one of them4 ,whatever their origin1 the earth's is the same4 ,it and they are formed from the same nebula1 controlled by the same central body1 subject to the same laws1 and destined for the same fate in the end4 ,in this1 the stars and the planets are not alike4 ,they all shine upon us with the same sweet friendliness1 and commonly we make no difference between them in our feeling for them4 ,but the stars are bright and beautiful acquaintances living far away in their own domain4 ,the planets are members of our own family1 bone of our bone and flesh of our flesh1 living comparatively near to us1 within the domain of our common source of life1 the sun4 ,one evening last autumn ,i was coming up ,broadway1 ,new ,york1 with a friend1 when we encountered at ,union ,square a man with a six-inch telescope directed toward the eastern sky4 ,he was soliciting those who passed to stop and look at ,mars and ,saturn4 ,both of these planets were then very bright4 ,they were also fairly near together1 and so low in the east that one could scarcely help seeing them4 ,but the people passed back and forth with hardly so much as a glance at the man and his telescope1 and for the most part never even raised their eyes to the sky with a passing curiosity to see what it might be that he wanted to show them4 ,my friend and ,i stopped and took each a view first of ,mars and then of ,saturn4 ,while we were looking at the planets1 a few of the passers-by began to loiter about1 half smiling at us for so playing in public1 slightly curious to see how we were faring at it1 but for the most part apparently indifferent to what we were seeing4 ,we had a fine view of ,saturn lightly resting in his nest of rings1 and an equally good view of the comical 8eye0 of ,mars4 ,after we had finished1 one or two others1 evidently prompted by our example1 followed us at the telescope4 ,one or two inquired of us what the stars were that had so interested us1 and one1 pointing to ,mars1 wanted to know if it was ,venus4 ,as the crowd grew larger a few more ventured to take a look1 much as they might venture to take their chance at hitting the bull's-eye in some shooting-gallery4 ,with the telescope pointed at ,saturn1 the man droningly chanted3 8,this planet is #hhg1jjj1jjj miles from the sun4 ,the ring you see is #agj1jjj miles in diameter10 and so on4 ,these1 to be sure1 were the facts--and most marvelous facts1 too--but without much meaning to one who knows nothing much about the planets2 and the manner of their recital certainly did not make them alluring4 ,i could not myself help feeling that the people there were missing a valuable opportunity1 and that it would be only fair to them for some one fairly to cry out3 8,come here and look at this planet4 ,it is different from anything else you have ever seen or ever will see4 ,it was at one time a part of the same nebulous mass that we were a part of4 ,it is in the same system of worlds with us4 ,it was formed in the same way that this world was formed4 ,it is in itself the most wonderful thing you ever saw1 and it is bound1 as we are1 to the sun by the ever-drawing tie of gravitation4 ,the very position of our own world in space is more or less influenced by it4 ,if anything should happen to it1 it might be a serious matter to us40 ,for it is true that we are thus closely bound to the planets4 ,the family tie among us is of far more force and significance than in any ordinary case of common origin4 ,human family ties wear1 as we know1 often into the merest threads1 or even become no ties at all4 ,but that between the earth and the planets remains apparently as close and strong as ever it was4 ,the law of gravity1 under which the earth draws toward its center every atom of matter surrounding it1 and thus holds together all the atoms composing it1 is not solely terrestrial in its application4 ,it is probably universal4 ,it certainly applies to every part of our little family of worlds4 ,every particle in the solar system attracts toward it every other particle in that system with a force determined by its mass and its distance4 ,the sun1 by reason of its immense size1 compels the earth and all the other planets forever to circle around it4 ,but the planets themselves have just as much power of attraction as the sun1 atom for atom4 ,thus1 while the sun controls the motions of all of them1 each pulls at the other1 and1 according to its power1 determines how much the path of each shall vary from the course around the sun it otherwise would make4 ,in the case of the smaller planets1 this gravitational influence is1 of course1 very slight1 and so subtle that we here on earth are not even conscious of it4 ,but it is1 nevertheless1 real and continuous4 ,it is greatest between the two largest planets1 ,jupiter and ,saturn2 but it was enough in the case of ,uranus and ,neptune to lead1 by its mere manifestation on the earth1 to the discovery of ,neptune1 the farthest planet4 ,being thus of the same origin with the planets1 having the same life history1 being bound to them in space by a tie that is perhaps eternal1 how can we fail to have the most intimate interest in their nature and all that concerns them8 ,but in addition to their close relationship to us there is1 to make them of peculiar interest1 the fact that1 after the sun and the moon1 they are for our eyes the most splendid objects in all the brilliant panorama of the sky4 ,such of them as we can see at all with the naked eye are most of the time much brighter than any first-magnitude star4 ,as they wander from constellation to constellation the soft light of their placid faces gives a beauty and variety to the spectacle that endears them to us1 and at the same time enhances by contrast their own charm and that of the glittering1 unchanging stars4 ,there is nothing that gives one such a sense of sweet familiarity with the heavens as a really recognizing acquaintance with the planets4 ,they are not1 like the stars1 associated with particular seasons4 ,they come sometimes with the gay company of stars that dance their way across the cold winter skies1 and sometimes with those that shine during the soft summer nights4 ,often in the spring and autumn we see some one of them before the sun is fairly down1 and1 before the light of an ordinary star can yet be seen1 hanging in lone brilliancy as the evening star2 and often an early riser has the reward of seeing one as a morning star glowing almost in the rays of the rising sun4 ,thus they are1 one and another1 with us at all times and seasons1 and it accords with the fact of the relation being a family one that we have in their coming and going a sense of frequency and informality which we cannot have in the more regular and seasonal coming and going of the stars4 ,,iii ,,what ,,the ,,planets ,,are1 ,,and ,,what ,,they ,,appear ,,to ,,be ,the planets are dark1 opaque bodies which revolve at varying distances and at varying rates of speed in orbits more or less circular around the sun as a center4 ,they have no light of their own1 as the stars have1 but shine wholly by reflected light received from the sun1 which itself is a star4 ,the amount of light they show to us depends upon their size1 their distance1 and their power of reflecting the light they receive4 ,in comparison with the stars1 the planets are very near to us4 ,our sun1 which is in constitution a star1 but very widely separated from any other star in the universe1 holds all his family of planets by the tether of gravitation1 and so keeps them circling about him in a very small space1 as astronomical space is measured4 ,to all of the planets except ,mercury1 we ourselves are nearer than the sun is4 ,to be sure1 this distance between us and the planets1 as measured by any terrestrial measure1 is not exactly small4 ,it is only by comparison that we can be said to have anything like a cozy relation to them4 ,for merely earthly affairs we use terrestrial measures4 ,in solar affairs we measure by an astronomical unit1 which is the sun's distance from the earth1 ninety-three millions of miles4 ,when we say a planet's distance from the sun is thirty astronomical units1 we mean it is thirty times farther than the earth is from the sun4 ,for matters outside of the solar system1 the unit of measure is the number of miles that light travels in a year4 ,the speed of light is a little more than #ahf1jjj miles in a second4 ,this is equal to about six trillions of miles in a year1 or about sixty-three thousand times the distance of the sun from the earth1 our family measuring-stick4 ,from the nearest star it takes light more than four years to come to us4 ,from the nearest planet light comes in less than three minutes1 and from the farthest one it makes the journey in a little more than four hours4 ,as compared with other heavenly bodies1 therefore1 the sun and the planets are very near together1 occupying a very small space in the immensity of the universe1 immeasurably isolated from all the other systems and1 so far as we know1 immeasurably smaller as a system than most of them4 ,the whole body of the planets is divided according to size into two classes1 the major and the minor planets4 ,when we refer generally to the planets1 the major planets only are meant4 ,the minor planets are usually called the asteroids1 or planetoids4 ,there are many hundreds of them1 and only one--and that barely--can be seen with the naked eye4 ,the other planets are eight in number1 including the earth1 which is1 after all1 nothing but one of the smaller of the major planets4 ,they are1 in the order of their distances from the sun3 ,mercury1 the nearest1 ,venus1 the ,earth1 ,mars1 ,jupiter1 ,saturn1 ,uranus1 and ,neptune4 ,of these only five--,mercury1 ,venus1 ,mars1 ,jupiter1 and ,saturn--can be seen from the earth without optical aid4 ,occasionally1 when ,uranus is very favorably situated1 a person with an exceptionally good eye1 who knows exactly where to look for the planet1 can see it4 ,neptune is about equal to an eighth-magnitude star in brightness1 and can never be seen without the aid of a telescope4 ,mercury1 while quite bright enough to be seen1 is not often situated favorably for observation4 ,it is very near the sun1 and is generally obscured either by the light of the sun when the sun and the planet are above the horizon1 or by the haziness of the atmosphere when the sun is below the horizon and the planet a little above it4 ,in regions of considerable altitude with a clear1 rare atmosphere1 ,mercury is more often seen2 but never for very long at a time4 ,the only planets1 therefore1 that are a part of our evening spectacle in the skies are ,venus1 ,mars1 ,jupiter1 and ,saturn4 ,these four happen to be not only the ones we oftenest see1 but also the most interesting of all the planets from various points of view4 ,venus and ,mars are the nearest to the earth1 and most resemble it1 and hence are the most inviting for speculations which have a human interest1 such as habitability1 the presence of life1 and kindred ideas4 ,jupiter and ,saturn are interesting above all the others in their splendor and size1 and in their importance as the centers of systems of their own4 ,as seen by us1 the planets are similar to the stars1 but with very distinct differences in appearance1 which1 when once familiar1 mark them so unmistakably as planets1 and not fixed stars1 that we need never get the two confused4 ,the first and easiest distinguishing mark to notice is that they do not twinkle1 as the stars do1 but shine with a steady light similar to that of the moon4 ,this is an invariable difference between stars and planets1 and one needs only to stop and truly look at them in order to detect it4 ,and once it has become familiar1 it discloses itself at a glance4 ,this difference between stars and planets is due almost solely to difference of distance1 though the twinkling is caused by our own atmosphere4 ,the stars are too far away to send us anything but a mere point of light1 and the unequal density of the waves of air sweeping over this point of light keeps it dancing before our eyes1 causing the phenomenon that we call twinkling4 ,but the planets1 being nearer to us1 show a disc1 from every point of which comes a line of light1 making the total light of some volume2 and these inequalities of the air are too small to interfere with it to any extent4 ,sometimes1 when the atmosphere is particularly unsteady1 it happens that the light of a planet is somewhat affected by it when the planet is just rising or setting and is1 consequently1 near the horizon1 and that it then seems to twinkle a little4 ,but this departure from the rule is always slight and of short duration1 in the case of the four planets most seen4 ,mercury1 never being seen anywhere except near the horizon1 often seems to twinkle2 but then he is seldom seen at all1 and1 when visible1 is in other ways so well marked that one cannot fail to recognize him4 ,so the steady light may justly be said to be invariable1 because the unusual conditions are easily detected4 ,when the atmosphere is such as to cause even the planets to blink a little1 it has an effect also on the stars4 ,at such a time they will appear to be fairly dancing4 ,this effect is apt to occur on the clear nights of winter1 the atmosphere being more unsteady then4 ,such nights1 because of the extreme liveliness and brilliancy that they lend to the stars1 are attractive times for amateur observations4 ,for the astronomer1 however1 they are not so favorable4 ,for the seeing of small details such as he seeks1 the steadiest atmosphere is necessary4 ,though the planets are near enough to show a disc1 they are not sufficiently near to show to the naked eye as sharp an outline as the moon's4 ,usually the edge is more or less rayed like that of a fixed star1 which adds somewhat to the difficulty of distinguishing them from the stars until their aspect has become familiar to us4 ,the fact that we are looking at a disc is plainly shown when an occultation by the moon occurs4 ,when the moon occults a fixed star1 it passes between us and the star4 ,at such times the star disappears behind the edge of the moon instantly1 as a mere point naturally would4 ,when a planet is occulted by the moon1 it disappears gradually as the moon covers more and more of its disc1 thus showing unmistakably the nature of it4 ,after steadiness of shining1 the next most obvious mark of difference between a planet and a star1 from our point of view1 is the movement of the planets4 ,a star remains always in one place with relation to the other stars1 while the planets move about from constellation to constellation1 seeming to travel sometimes toward the east and sometimes toward the west4 ,this difference also is due solely to a difference of distance4 ,the stars as well as the planets are constantly in motion4 ,most of them1 in truth1 move at a rate which would make the rate of motion of a planet a mere snail's pace in comparison4 ,arcturus1 for instance1 is supposed to be moving at the rate of two or three hundred miles a second1 and there are other fixed stars with an equally rapid motion4 ,the swiftest moving of the planets does not achieve much more than twenty-nine miles a second1 while the slowest swings along at a rate of but little more than three miles in the same length of time4 ,these are the real rates of speed of the stars and planets2 but they are not at all what they seem to us4 ,the difference in distance is so great that for centuries and centuries the flying stars have seemed to men to remain in the same place in the skies1 and so we call them fixed4 ,the planets1 so slow-journeying as they are in comparison1 seem to us to be moving among the constellations at rates varying from more than a degree a day in the swiftest to between two and three degrees a year in the slowest4 ,hence1 if through lack of practice in observation a person is not at once able to distinguish the difference between the stars and the planets in the character of their light--that is1 whether they twinkle or shine steadily--he can1 by taking a little longer time1 at most only a few days1 determine whether the object he sees is a star or a planet by noticing whether it has any motion among the other stars4 ,venus and ,mars will show some movement in one evening4 ,jupiter and ,saturn may require a little more time to disclose their motion4 ,,iv ,,the ,,origin ,,of ,,the ,,planets ,different as the planets are as individuals1 they have too many characteristics in common to admit any question of their common origin4 ,they are not simply stars of one sort and another that happen to lie nearer to us than the great body of stars that spangle the heavens1 but are1 without doubt1 all of one family with us in their origin1 as well as in their situation4 ,how they originated1 and exactly what has been their course of evolution1 has long been an engrossing problem among philosophers2 and it is not yet solved4 ,in the sense that the human race is all of one family1 the planets are but a part of the great universe that lies about us and is in part visible to us4 ,the forms in which we know matter as existing in the universe1 outside of the solar system and of the minor forms in our own world1 are those of stars and nebul4 ,it seems as if either of these could1 and in fact does1 form out of the other4 ,we do not at all know how in the beginning matter took the form of either1 or which came first4 ,but it is believed that a star is formed by the condensation of a nebula1 and that a nebula is often formed by the collision or near approach of two stars and the consequent disintegration of their particles4 ,the sun is a star not very different from most of the other stars1 as we believe them to be1 except that it is smaller than most of them4 ,it is the center around which we and all the planets revolve1 and it is believed that we were all once a part of the very body of it4 ,for astronomers are substantially agreed that the whole solar family1 including the sun and all the planets1 has been evolved from a great nebula which1 in one form or another1 at one time filled practically the whole of the immense space from the sun to the outermost planet of the system4 ,while this cannot be said to have been exactly proved1 yet it accords with all the known facts of the solar system4 ,as to how this nebula originated1 and what its shape was1 and in just what way the planets were formed from it1 there is more diversity of opinion4 ,up to the middle of the eighteenth century no really scientific theory of the evolution of the solar system was formulated1 and it was not until the very last years of that century that any theory of the origin of the planets was published which received anything like universal acceptance4 ,this was the case1 however1 with the famous nebular hypothesis of ,laplace1 which was published in #agif1 and for a time seemed so nearly to account for the various phenomena of the motions and relations of the planets that it was not only accepted in the scientific world1 but became almost as much a part of universal knowledge as that the earth is round4 ,but even this theory has not completely stood the test of time1 which inevitably brings that close scientific investigation that any theory must undergo when it is used as a working basis to which all facts and secondary theories must be correlated4 ,the original nebular hypothesis supposed this vast nebula to be in rotation on its axis4 ,as it condensed1 the falling-in of the particles caused its rotation to become more rapid1 until finally1 under the strain of this1 a ring of matter was 8thrown off0 from the outer edge4 ,or1 as was sometimes said1 the inner part condensed and left a detached ring of matter4 ,this ring1 continuing to rotate in the direction given it by the rotation of the central mass1 finally condensed into a planet1 rotating on its axis and revolving about the central sun in the same direction as the ring had revolved4 ,the satellites of the planets were thought to have been formed by the same process from the planets while these were still in a plastic state4 ,saturn1 with its wonderful system of rings and satellites1 was thought to be a minute object-lesson of a planet in course of evolution1 and this we have often heard said4 ,i am sorry it is not so4 ,i had much enthusiasm in my youth over this beautiful and orderly arrangement of things3 first1 the splendid hypothesis1 the achievement of a noble mind2 then the little model showing the work in its progress2 and1 finally1 the beautifully finished system1 the rings all rolled up into planets1 traveling unceasingly in paths which eternally marked the size of the central body1 or sun1 at the time of the separation4 ,but it is now pretty certain that this cannot be the way it all happened4 ,closer investigation shows that there are mechanical difficulties which were not at first fully recognized4 ,a series of rings could not have been left off by a body so wholly gaseous4 ,the particles composing them would not be sufficiently coherent to permit of separation in any such compact1 uniform1 and decisive manner4 ,then1 even if such a ring were thrown off1 it is not at all certain that it could condense into a planet4 ,its tendency1 indeed1 would be to disintegrate rather than to condense4 ,in a body so tenuous the mutual gravitation of its particles would be too feeble to complete the work4 ,besides1 in conflict with the theory is the fact that a few of the satellites of the planets revolve in a direction contrary to that of the planet4 ,and there are other minor1 but still important1 details in the mechanism of the solar system which cannot be accounted for by the ring theory4 ,and so1 while astronomers are still agreed that the whole solar system1 which includes the planets1 was evolved from a primeval nebula1 the theory of leaving off rings which condensed into planets is not found tenable1 and the search for some more acceptable theory or some modification of the ,laplace theory is now occupying a number of eminent astronomers and philosophers4 ,the result of all this is that no theory of the manner of the evolution of the planets is definitely accepted by the body of astronomers4 ,much hard labor and ingenious reasoning have been expended in endeavoring to formulate some hypothesis by means of which we may account for observed phenomena4 ,the astronomers with whom these theories have originated are1 naturally1 more or less ardent in setting them forth4 ,thus one occasionally sees a decisive and authoritative statement of a theory of the evolution of the planets that seems at first view to account for everything4 ,but no one of these has yet been entirely accepted by astronomers1 who are as a class cautious and conservative1 and are necessarily critical of any theory1 because the value of much of their future work depends upon its accuracy and sufficiency for all details4 ,the theory which at present seems more nearly than any other to offer a reasonable explanation of most planetary phenomena is based upon the supposition that the nebula from which the sun and planets were evolved was in the shape of a spiral1 and not the gaseous mass that the original nebular hypothesis supposed4 ,the fact that among the many thousands of nebul that have been discovered and observed a very large proportion of them are in this form1 aside from any other consideration1 suggests a great probability that the one from which the solar system was evolved was a spiral4 ,the spiral nebul seem to be of a somewhat different constitution from the other nebul1 and show on observation spots of condensation here and there1 which at least suggest the formation of systems of planets4 ,this indicates that ours may be only one of many such systems in process of evolution2 but it is certainly among the smallest of them1 for most of the spiral nebul are immensely greater in size than the one required to form our little system4 ,its few trillions of miles of diameter1 though it seems so vast to us1 is quite insignificant in comparison with a large proportion of the spiral nebul in the universe4 ,a spiral nebula is in the form of a disc somewhat resembling that familiar form of fireworks known as a pinwheel4 ,the typical form of it has two arms projecting from opposite sides of the whirling figure4 ,it is much denser toward the center1 where the spiral would naturally be more tightly wound1 and has smaller spots of condensation scattered like knots here and there along the fiery arms4 ,in the process of evolution the denser center becomes the controlling sun1 and the smaller spots of condensation form the planets1 which are eventually detached from the revolving mass1 but continue to revolve about the center as they were doing from the beginning4 ,according to the mass it has in the beginning1 the planet gathers up by gravitative attraction all the material in its region1 gaseous or more or less condensed1 and grows by this accretion4 ,if the nucleus happened to be a large one before it separated from the parent body1 it will have sufficient force of gravitation to gather in large quantities of material and greatly increase its size1 and thus become a large planet4 ,if it is only a small nucleus1 it has less power of attraction1 and gathers in less material4 ,when these condensations of matter which are the nuclei of the planets break away from the parent body1 they sometimes carry with them still smaller nuclei1 which1 if they are not too near the original center1 or sun1 are destined to remain under the control of the planets and become their satellites4 ,the number and size of the satellites a planet has depends upon the size1 and hence the controlling force1 of the nucleus which is its foundation1 and also upon the number of spots of condensation that chanced to be formed in its neighborhood sufficiently near to come under the gravitational control of the planet4 ,if by any chance the nucleus which was to form the largest satellite of ,jupiter had been in the situation of ,mercury1 for instance1 it might well have given its allegiance to the sun1 instead of to ,jupiter1 and thus have become a planet4 ,under the ring theory the outermost planet1 ,neptune1 would be the oldest of the planet family1 and the one nearest the sun1 ,mercury1 would be the latest born and youngest4 ,but the physical development of these planets seems to indicate1 in truth1 exactly the opposite of this1 as we shall see later on4 ,under the spiral-nebula theory the planets may be nearly of the same age1 their different states of development being due mainly to difference in size and to some peculiarities of situation4 ,if the nucleus happened to be near the outer edge of the spiral1 it would be formed from the lighter matter composing the outer part of the nebula1 and this seems to be the case with the outer planets4 ,if it were near the dense center of the nebula1 it would be composed of denser material1 and this seems to be so in the case of the inner planets4 99 99 99 99 99 ,a nebula1 it is thought1 is formed by the collision or the near approach of two of the many stars1 or suns1 that we know are traveling about at high velocities as vagrants here and there through space4 ,if the two bodies come together centrally1 the force of the impact will generate heat sufficient to convert them into a nebula2 but this will not necessarily be spiral in form4 ,if they come together obliquely1 the chances are that they will form into a rapidly rotating spiral disc4 ,but in order to form a spiral1 it is not necessary that there should be an actual collision4 ,because of the force of gravitation the near approach of two stars would subject them to an enormous strain from their pull upon each other1 and there is a limit within which they cannot approach without being literally torn to pieces from the effect of this tidal force4 ,even if they do not approach within this fatal limit1 which is a little less than two and one-half times the radius of the body1 they may come so near as to change their character entirely1 and1 through their tidal influence on each other1 form into a rotating spiral nebula with two arms projecting from opposite sides of the spiral4 ,it now seems probable that it was after this manner that the sun and its family of planets were formed4 ,the matter which is contained in them may have been in the form of a dark1 solid body pursuing some sort of course in space4 ,in its journeying it came near another body and was awakened into a life of activity in the form of a flat1 spiral nebula which was left spinning around in a pyrotechnic manner1 the matter composing it much diffused at the outer edges and densest in the center4 ,scattered through it were the more or less condensed spots which were the embryonic forms destined to come forth from the parent body as the individual planets4 ,when the separation was completed1 each planet fed and grew upon all the matter that it had the force to draw to it1 and it swept clean the space that lay within the limits of its power4 ,if the particles thus gathered in were small and slow of motion1 they became a part of the body of the planet4 ,if they were large and swift1 they became members of the planet's family as satellites4 ,in whatever area of the nebula each planet came into a separate existence1 it fed upon the matter which that area afforded4 ,in the case of ,neptune1 at the outer edge of the system1 it was very diffuse matter2 in ,mercury's region1 nearer the center1 it was more dense4 ,thus in our family of planets1 though its members were born of the same parent and developed under the same guiding laws1 each has a distinct individuality arising from its inherent qualities and its environment during the early stages of its existence4 ,the spiral-nebula theory seems to offer a better explanation of these individual qualities than any other that has been advanced thus far1 and in its main features it is pretty generally accepted4 ,but one must keep in mind that the details of any theory of the beginning and growth of the planets are more or less speculative1 or1 at least1 have not yet been proved with finality4 ,v ,,the ,,seven ,,great ,,planets ,so far as we know1 five of the planets--,mercury1 ,venus1 ,mars1 ,jupiter1 and ,saturn--have been known from time immemorial4 ,there are existing records of them made thousands of years ago4 ,there is no reason why they should not have been thus known1 since they have always been as they are now1 visible to the naked eye1 and all of them save ,mercury are as easily seen as the sun or the moon4 ,they do not1 of course1 exact the instant attention that those great luminaries do1 because1 being smaller1 they are less isolated from the great body of the stars2 but they are in their seasons plainly visible1 and can then always be seen if one looks at them4 ,in ancient times1 when people lived more out-of-doors than is the habit now1 they did look at them4 ,the same primitive shepherds that1 while tending their flocks at night on the hills1 named the constellations according to the fanciful shapes that the unchanging stars seemed to outline1 watched also the five wandering stars1 more wonderful to them than any of the others4 ,they observed how mysteriously these stars came at certain seasons and silently threaded their way across the shining heavens1 and then as mysteriously disappeared4 ,they saw them not only differing from the other stars in glory1 but changing in their own brilliancy from one time to another1 until1 in some cases1 they failed to recognize them as the same stars under varying aspects4 ,venus1 for instance1 they called ,phosphorus1 or ,lucifer1 when they saw her as a morning star1 and ,hesperus1 or ,vesper1 when she shone in the evening4 ,the sun and the moon1 they noted1 also moved from place to place among the fixed stars1 and they called all these errant bodies planets1 which means 8wanderers40 ,these are the 8seven planets0 referred to in the earlier literatures and in all early books on astronomy or astrology4 ,this is sometimes a little confusing1 because1 though the sun and the moon are no longer called planets1 we still 7omitting the earth7 have seven4 ,but ,neptune and ,uranus1 not being visible to the naked eye1 were not known to the ancients4 ,they were discovered by means of the telescope1 and that only within the last century and a half4 ,so1 owing to these comparatively new-found members of the solar family1 we have yet the magic number of planets1 seven4 ,these seven are the major planets and the ones with which mainly it will be our endeavor here to promote and strengthen an acquaintance4 ,with ,uranus and ,neptune the acquaintance will necessarily be less intimate than with the others1 because we cannot see them in the same free way2 but they are not on this account much less interesting than the others1 and a little knowledge of them is pleasant family history4 ,they simply do not live within sight4 ,the planets that are nearer to the sun than we are1 and hence lie between us and the sun1 are called the inferior1 or sometimes interior1 planets4 ,those that lie outside the orbit of the earth are called the superior1 or the exterior1 planets4 ,in so grouping them the earth is the dividing-point1 and is not itself in either class4 ,mercury and ,venus are the inferior planets4 ,the superior planets are ,mars1 ,jupiter1 ,saturn1 ,uranus1 and ,neptune4 ,the distinction has importance1 especially when we are discussing the planets with relation to their movements1 as seen from the earth1 because the planets with orbits between us and the sun 7the inferior planets7 have very different phases and apparent motions from those whose orbits are beyond us from the sun 7the superior planets74 ,when considered in regard to size1 constitution1 development1 and their likeness to each other1 the planets are sometimes distinguished as the terrestrial planets and the major planets4 ,this need occasion no confusion with the general division of them into major and minor planets1 because1 as has been said1 when simply 8the planets0 are mentioned1 these seven large planets are always the ones that are meant1 the others being usually called asteroids1 or planetoids4 ,the terrestrial planets are ,mercury1 ,venus1 ,earth1 and ,mars4 ,as the name implies1 they are so called because they are in some respects similar to the earth4 ,the major planets are ,jupiter1 ,saturn1 ,uranus1 and ,neptune4 ,they are all larger than the terrestrial planets1 and1 in addition1 have some other characteristics in common which the planets of the other group do not have4 ,the two classes represent different stages of evolution4 ,the four planets forming the terrestrial group are sometimes called the inner planets1 and the four major planets are then known as the outer planets4 ,the point of division in mind then is the space between ,mars and ,jupiter4 ,this is so vast in comparison with the spaces between the other planets from the sun out to ,mars that it becomes a convenient dividing-line1 particularly as the groups divided by it are in some respects essentially different from each other4 ,of the four planets which have an especial interest to us because of their being the ones most easily seen1 two are terrestrial1 or inner1 planets1 ,mars and ,venus1 and two are major1 or outer1 planets1 ,jupiter and ,saturn4 ,the differences between the two classes are solely matters of constitution and situation1 and have nothing to do with their appearance to us4 ,venus1 the brightest of them all1 belongs to one group2 ,jupiter1 the second in brilliancy1 belongs to the other4 ,that there is at least one other planet beyond the present boundary of our system 7which is the orbit of ,neptune7 seems to be quite probable4 ,some astronomers think there may be several others4 ,there are certain perturbations1 or irregularities1 in the movements of ,neptune which the influence of ,uranus does not account for1 and they seem to indicate that there is some disturbing body even beyond the orbit of that farthest known planet4 ,several astronomers are working on the problem of locating this undiscovered body4 ,at various times it has been announced that such a planet would probably be found in a certain position in the skies at a specified date2 but as yet no one has been able to get a view of it4 ,recently the orbit of a far-off hypothetical planet has been calculated1 and its place predicted for #aiad4 ,perhaps it may be found then4 ,of course it could never be seen through any but the most powerful telescopes4 ,its calculated distance from the sun is one hundred and five times that of the earth4 ,this would be more than nine billions of miles1 or more than three times farther than ,neptune is from the sun4 ,it would require fourteen hours for light to pass from the sun to a planet at that distance1 and the sun would appear to it smaller than ,saturn or an ordinary first-magnitude star does to us4 ,a further reason for suspecting the existence of such a planet is suggested by the orbits of certain comets4 ,these erratic bodies1 when they chance to come within the bounds of the solar system1 are sometimes forced to remain because of the powerful influence of one of the planets near which their path has taken them4 ,jupiter holds as many as thirty of them in this way1 ,saturn and ,uranus have two or three1 and ,neptune has captured as many as six4 ,but there are still others that return to us in regular periods1 but which go sufficiently far beyond ,neptune to escape entirely if there were not some still more distant watch-dog to turn them back4 ,so there seems good reason to believe that ,neptune is not really the outermost of the planets4 ,there has also been much said about the possibility of a planet nearer to the sun than ,mercury4 ,when ,mercury is at perihelion1 or nearest to the sun1 there are certain irregularities in his movements which might be explained by the presence of another planet between ,mercury and the sun4 ,in #ahei it was thought that such a planet had been observed4 ,its time of revolution and its distance from the sun were estimated1 and it was named ,vulcan4 ,in some of the books of astronomy published about that time1 and even in some published as many as fifteen years later1 ,vulcan is mentioned as a reality4 ,but now it is believed that the observation was a mistake1 and no such body is known to exist4 ,in #ahgh it was again thought that two bodies nearer to the sun than ,mercury had been discovered during an eclipse4 ,these observations have never been explained or confirmed2 but it is thought that the objects seen were probably stars which were mistaken for planets by the observers4 ,if a body so situated does exist1 it is so near the sun that it probably can never be seen except during an eclipse1 and the time of observation is then so short and mistakes are so easily made that it is difficult to verify the observation4 ,the continued search for the cause of the perturbations of ,mercury may finally lead to the discovery of something between it and the sun4 ,but if it is a single body1 this seems a much less promising task than the search for a planet1 or planets1 on the outer edge of the solar system4 ,,vi ,,the ,,movements ,,of ,,the ,,planets ,in considering the movements of the planets1 we have to regard their actual motion in space and that motion as it appears to us4 ,they all have two principal motions in space4 ,they revolve about the sun in their orbits1 and they rotate on their axes4 ,the manner in which they accomplish the rotation on their axes determines the length of their days and nights1 or whether1 indeed1 they shall have any such grateful alternations of light and darkness4 ,those planets which1 like the earth1 turn on their axes in less time than they make their journey around the sun have one day and one night every time they make a complete rotation4 ,those that turn on their axes in the same time that they revolve around the sun1 of which sort there seems to be at least one1 face always toward the sun1 and have no alternations of day and night4 ,on one side it is always day2 on the other it is always night4 ,the number of days a planet has during each revolution around the sun depends upon how much time it requires to make a revolution1 and how fast it spins on its axis4 ,in one year here on the earth we have three hundred and sixty-five days and nights4 ,saturn1 in its year1 has more than twenty-three thousand days and nights4 ,the manner in which the revolution of the planets in their orbits takes place determines the length and character of their year2 the nearer a planet is to the sun1 the shorter its orbit is1 and the faster the rate of speed at which the sun compels it to move1 and hence the shorter its year4 ,the nearest of the planets1 ,mercury1 makes more than five hundred revolutions around the sun1 while the farthest1 ,neptune1 makes one4 ,three times in a year--that is1 a terrestrial year--the nearest planet speeds around its orbit and back to the starting-place with seventeen days to spare4 ,one hundred and sixty-five terrestrial years are necessary for the farthest planet to make one circuit of its orbit4 ,the first goes at the average rate of nearly thirty miles a second over a path more than two hundred million miles long4 ,the second travels a path more than seventeen billion miles in length1 at the average rate of three and four-tenths miles a second4 ,between these two extremes the other planets have orbits and rates of speed varying with their distances from the sun4 ,the farther they are from the sun1 the larger the orbit and the slower the speed4 ,to get something like a picture of the sun and the planets as they actually lie and as they move in space1 one should have in mind an immense flat1 circular disc five and a half billions of miles in diameter passing through the sun1 which is in the center of it4 ,around the edge of the disc is the orbit through which ,neptune moves4 ,at varying distances inside of it are the orbits of the other planets1 each growing smaller and smaller as one comes nearer and nearer to the sun1 until the orbit of ,mercury1 the planet nearest to the sun1 is reached4 ,since it is not a hard metal disc that we are considering1 but only an imaginary one in space1 there may be a little latitude allowed for the orbits to tip somewhat out of the exact plane of the disc without materially altering the figure in mind4 ,and this they do1 very slightly--most of them to the extent only of from one to two degrees1 though one of them falls outside of the common plane about seven degrees4 ,in these orbits all the planets1 as seen from the sun1 are going around from west to east4 ,at the same time they are turning on their axes in the same direction1 some standing almost erect1 as it were1 in their orbits and whirling like a dancing dervish as they skim along1 and others more or less inclined like a traveling top4 ,the time a planet requires to make one circuit of its orbit constitutes1 as with the earth1 its year4 ,but we who are on the earth have1 in our study of another planet1 to regard it as having in a sense two years4 ,first1 there is the time it takes1 starting from a given point in its orbit1 to circle around the sun and return to that point4 ,this is known as its sidereal period1 or year1 and is so called from sidus1 meaning a star1 because the only way to mark any point in space is by a fixed star1 and1 as viewed from the sun1 one revolution of a planet would be from a given star back again to that star4 ,then there is the time a planet takes1 starting when it is in a straight line with the earth and the sun in space1 to return to the place where the three bodies will be again in the same relative position4 ,this is known as its synodic period1 or year4 ,synodic is from our word synod1 meaning a meeting or assembly1 and the synodic year is the time between two successive and similar meetings of these three bodies4 ,the sidereal year concerns the planet in its relation to the sun2 the synodic year1 in its relation to the earth4 ,the synodic year is the only one that much concerns us while regarding the planets as a part of the spectacle of the sky4 ,it is the one that we know from observation1 while the sidereal year is mathematically computed4 ,the two periods1 or years1 are not of the same length1 because the sun with reference to the planet is always stationary1 and the motion resulting in the sidereal year is that of the planet only1 while the synodic year is the result of the movements of both the earth and the planet1 each1 in its own orbit1 being always in motion4 ,an inferior planet1 situated as it is nearer to the sun than the earth is1 and so having a shorter orbit than the earth's1 will1 when it finishes its sidereal year and comes around to the point from which it started1 find the earth advanced from that position and will1 therefore1 have to travel farther on in order to overtake it and come into the same relative position from which they started1 which makes the time of its circuit with reference to the earth obviously longer than with reference to the sun4 ,with the superior planets the case is just reversed4 ,the earth is the inside planet1 or the one nearest the sun1 and it must overtake them4 ,with one exception1 they are all so far away from the sun and move so slowly that it takes us but little more than one of our years to overtake them and bring them into the same relative position with us that they had when we started1 while it requires many of our years for any one of them to make a single circuit of the sun4 ,hence their circuit with reference to the earth is shorter than with reference to the sun4 ,with ,mars1 the exception referred to1 we have a more hardly fought race4 ,that planet is not so far from us as are the other superior planets4 ,it makes its revolution around the sun in a little less than two of our years4 ,we travel eighteen miles a second1 and it travels fifteen miles in the same length of time4 ,if we are in line with it at the beginning of our journey1 we glide off swiftly1 and easily leave it far behind4 ,when1 however1 we come back to the starting-point1 it has not loitered1 and is many millions of miles ahead of us1 and it remains ahead until more than seven weeks after we have returned to the starting-point a second time4 ,fifty days after we have begun to make our third round we overtake it1 and are again in a direct line with the planet and the sun4 ,this makes its period with reference to the earth ninety-three days longer than its own year1 and fifty days longer than two of ours4 ,this is the longest synodic period among the planets4 ,the orbits in which the planets move all have the form of an ellipse--that is1 of a circle more or less flattened4 ,this flattening1 or the extent to which an orbit departs from the form of a true circle1 is called its eccentricity4 ,the sun is never at the exact center of an orbit1 but is always situated a little to one side of the center--that is1 it is at one of the foci of the ellipse4 ,consequently1 the planet1 as it travels in its orbit1 is not always at the same distance from the sun1 the amount of the variation in distance depending upon the eccentricity of the orbit4 ,the point in the orbit where the planet is nearest to the sun is its perihelion1 and the point at which it is farthest is its aphelion4 ,it is necessary to keep these elementary facts in mind in order fully to understand the changes in the motions and brightness of the planets4 ,the influence of one body over another that is circling around it is to make it move faster or more slowly according to its distance from the central body4 ,since a planet varies in its distance from the sun in the different parts of its orbit1 it is forced to move fastest when it is in that part of the orbit which is nearest to the sun1 and slowest when it is in the part farthest away4 ,in other words1 the motion of a planet is more rapid at perihelion than at aphelion4 ,the earth is in perihelion1 or nearest to the sun1 in winter--that is1 winter in the northern latitudes--and in consequence it moves faster in winter than in summer1 and the northern winters are1 for this reason1 a little shorter than the summers4 ,these two simple movements of the planets--that around the sun and that on their axes--are their principal real movements1 and are such as they would show to be if seen from the sun1 which is the center of them4 ,there are also certain minor real movements arising from various causes1 one being the influence that the planets exercise on one another2 but for the ordinary observer these have no particular significance4 ,then1 the planets all share the one grand movement which the sun itself is known to be making through limitless space to a destination of which we are in utter ignorance1 over even a path which we know nothing of save that it leads toward the bright star ,vega1 in the constellation of the ,lyre4 ,as the sun moves on in that direction at the rate of eleven miles a second he takes with him all his family of planets and planetoids1 with their satellites1 and whatever other bodies have their abode in his domain4 ,thus they travel as a body1 each individual spinning on its axis1 from the sun itself down to the smallest planetoid1 the satellites circling around the planets1 and the planets in their turn around the sun4 ,and in all these movements the earth takes part as one of the planets4 ,the sun itself is following a comparatively straight line in space1 and1 so far as we know1 in allegiance to no other body4 ,it is1 though1 just possible that this comparatively straight line may be the arc of a circle so vast that we have not yet had time to discover its curvature1 and that the sun itself may be pursuing its own circuit around some still more powerful body4 ,,vii ,,how ,,the ,,inferior ,,planets ,,seem ,,to ,,move ,of the real movements of the planets1 as described in the last chapter1 we get here on the earth only a very fragmentary view4 ,without the aid of the telescope none of them is visible to us except the movements in their orbits1 and these1 to our view1 are somewhat different from the simple1 circling course apparent to an observer on the sun4 ,the difference is due to the fact that the earth itself is always in movement in just the same way that the other planets are1 and we1 being never at any time at the center of the orbits1 do not see the movements of the planets as they truly take place1 but only as they are outlined against the sky4 ,so the appearances and disappearances and visible travels among the stars by which we know the planets are only as we see them4 ,some knowledge of the real movements is necessary to a proper understanding of the apparent movements2 but it is only with the latter that1 for ordinary observation1 we need to be particularly acquainted4 ,the rotation of the earth on its axis1 as we know1 causes the familiar daily apparent rising1 passing1 and setting of all the heavenly bodies4 ,in this apparent motion the planets share as well as the sun1 moon1 and stars4 ,but it is their movement among the fixed stars1 and not with them1 that distinguishes them as planets1 and this it is necessary to know in order to keep track of them and be able to recognize them in their varying places and guises4 ,for they sometimes shine in their greatest glory in one season1 and sometimes in another1 and at the recurrence of the same season they are sometimes in one part of the sky and sometimes in another1 so that their ways of coming and going border almost on the mysterious1 until one learns the manner of this apparent vagrancy4 ,happily1 this knowledge is easily attained1 and then the matter is simple enough4 ,the apparent motions of the inferior planets1 ,mercury and ,venus1 always take place near the sun4 ,venus never wanders more than forty-eight degrees from it1 and ,mercury never more than twenty-eight4 ,most of the time they are much nearer than this4 ,since we cannot see either of them except when the sun is below the horizon1 the consequence of their being always thus near to him is that they are in view for only a short time after the sun has set or before he has risen4 ,if they are in the evening sky1 and hence east of the sun1 they soon follow him when he sinks below the western horizon4 ,if they are west of the sun1 and1 consequently1 are the first to rise in the morning1 it is not long before his brilliant rays flood with light the eastern sky and blot the planets from our view4 ,venus can be seen sometimes for three hours at a time1 ,mercury for never more than one4 ,within this limited region of the sky they appear to journey evening by evening away from the sun1 somewhat obliquely1 but toward the zenith1 until they have reached the end of their tether4 ,then they journey back and pass to the other side of the sun4 ,there they climb their path toward the zenith1 moving westward and1 as we see them1 obliquely upward4 ,morning by morning they get farther from the sun until their westward limit of freedom is reached1 when they again draw in toward the sun1 pass it1 appear in the evening sky1 and pull off up the sky toward the east again4 ,thus they swing from east to west of the sun1 and back again1 in unceasing repetition4 ,as they pass the sun going from east to west--that is1 from the evening to the morning sky--the inferior planets go between us and the sun2 and when they swing back from west to east1 or from the morning to the evening sky1 they pass on the side of the sun farthest away from us4 ,when they are in a direct line with the earth and the sun they are said to be in conjunction4 ,if at this point they are between us and the sun1 it is inferior conjunction4 ,if they are on the other side of the sun1 they are said to be in superior conjunction4 ,when the planet1 as seen in the evening1 has traveled toward the east as far from the sun as it will go during that particular revolution1 it is said to be at its greatest eastern elongation4 ,elongation means simply apparent distance from the sun2 hence1 greatest eastern elongation is the greatest distance possible east of the sun from our point of view4 ,greatest western elongation1 which we see in the morning before dawn1 occurs when the planet is at its greatest apparent distance west of the sun4 ,while apparently drawing near and then away from the sun1 traveling obliquely up and down the evening and the morning sky1 the planet has all the time been moving in one direction around the sun2 but we could see the motion only as it appeared on the background of the sky4 ,the planet is in reality just as far from the sun when it is in conjunction as at elongation4 ,the difference is that we see it at a different angle1 or from a different point of view4 ,but it has not been at all times equally near to the earth4 ,when an inferior planet is at greatest eastern elongation1 it is1 of course1 east of the sun1 and can be seen above the sun in the evening after sunset1 and is an evening star4 ,as it moves westward nearer and nearer to the sun1 it is above the horizon a proportionately shorter time each evening1 and is more and more obscured by the sun's rays until it reaches inferior conjunction1 when it is exactly between us and the sun1 and hence at the point nearest to us4 ,here it becomes invisible1 largely because it has its dark side toward us1 but partly because the dazzling light of the sun entirely obscures it4 ,once in a while our relative positions are such that we see it pass like a black dot directly over the bright face of the sun4 ,this is called a transit4 ,but a transit does not occur at every inferior conjunction4 ,it would so occur if the planet's orbit and the earth's were in exactly the same plane4 ,but the small tilt that they have is sufficient to throw the planet1 when it is passing the sun1 into such an angle that it does not pass directly between the disc of the sun and us1 but a little above or below4 ,thus transits are rather rare1 though they occur periodically in the case of both ,venus and ,mercury1 and will be spoken of elsewhere4 ,when the planet has passed inferior conjunction1 it is then west of the sun1 and rises in the morning before the sun is up1 and is a morning star4 ,for a few days it can be seen either not at all or with difficulty4 ,then1 as it works its way out of the rays of the sun and on toward the west1 it rises earlier each morning until it reaches its farthest point west4 ,as it starts back east again its distance from the earth increases daily until it reaches its greatest distance from us at superior conjunction4 ,it is then the whole diameter of its orbit farther from us than when it was at inferior conjunction1 and it is again invisible4 ,the illuminated side of it is toward us2 but it is at its smallest1 because it is at its greatest distance from us1 and even when it is not directly behind the sun the light of that luminary is too great for successful competition4 ,after it has passed superior conjunction it is again in the evening sky1 apparently moving farther from the sun each day4 ,it is at the same time actually coming nearer to us each day1 and these two facts cause a daily increase in its brightness4 ,but an inferior planet is not1 like the superior planets and the stars1 brightest when it is nearest to us4 ,it is1 in fact1 darkest when it is nearest--that is1 when it is at inferior conjunction--and we cannot see it at all4 ,this is because an inferior planet passes through phases1 like the moon1 changing gradually during its rounds from full to crescent1 and back again4 ,its full face is toward us when it is on the opposite side of the sun and farthest from us4 ,the proportion of the face that is illuminated grows smaller as the planet approaches its eastern elongation4 ,but the planet grows brighter because it is coming nearer to us and is getting out of the dazzling rays of the sun4 ,one-half of its surface is illuminated when it is at greatest elongation2 but it is brightest a few days later1 when less than half of its face is illuminated1 because it is enough nearer to compensate for the slight diminution in the proportion of light on its disc4 ,it is brightest in the morning a short time before its western elongation1 for the same reason4 ,this in a general way describes the motion of an inferior planet1 and this is all that we need to know in order to understand its ordinary visible movements4 ,if we watch it carefully1 however1 we may detect that shortly before inferior conjunction it pauses in its onward sweep and seems for a time to be stationary1 and then to retrace its way among the stars until a short time after inferior conjunction1 when it again pauses and appears stationary1 and finally starts off again in its original direction on its way toward greatest western elongation4 ,during this capricious sort of progress the planet usually describes more or less of a loop1 sometimes almost a flourish1 in its path4 ,the appearance is wholly due to the planet's overtaking and passing us in our journey around the sun4 ,for a time it travels behind us1 then beside us1 and then beyond us2 and1 since we are both in motion1 the effect is much the same as when one train passes another while they are both traveling in the same direction4 ,the orbits of the earth and the planet are not exactly in the same plane1 and1 both bodies being in motion1 we are not in a position to see the planet at the same angle more than once as it seems to pass back and forth1 and so we get the effect of its making a flourish or loop4 ,but this effect1 while interesting1 takes place only when the planet is so near the sun that to the ordinary observer it itself does not count for much4 ,we can see but little of the inferior planets at that time1 anyway1 though it is important for us to know where they are1 in order to keep track of them and to be ready for them when they are to be seen4 ,,viii ,,how ,,the ,,superior ,,planets ,,seem ,,to ,,move ,the movements of the superior planets1 ,mars1 ,jupiter1 ,saturn1 ,uranus1 and ,neptune1 as they appear to us1 are different from those of the inferior planets in some important respects4 ,instead of swinging back and forth east and west of the sun1 and never appearing very far away from it1 as the inferior planets do1 the superior planets make an entire circuit of the heavens1 and it is possible to see them at any distance from the sun1 and at any time during the night4 ,sometimes they are1 with relation to the earth1 in that part of the sky exactly opposite to the sun1 and hence in line with it and the earth4 ,at such times they can be seen all night4 ,they are then said to be in opposition1 and are in the best position for our observation4 ,the earth being1 when in this situation1 in a direct line between them and the sun1 we have the sun at our backs1 as it were1 shedding its full rays on the disc of the planet under observation1 which is then at its nearest to us1 and also at its brightest4 ,for1 since the orbits of all the superior planets are outside of ours1 the planets never get between us and the sun1 and1 in consequence1 never turn a dark side toward us4 ,their entire discs are practically always illuminated1 and their changes in brightness depend largely upon their changes in distance1 which1 as we have seen1 is not the case with the inferior planets4 ,mars1 the nearest of them1 is at times somewhat gibbous 7that is1 shows a little less than a full face1 as the moon does when just beginning to wane71 and1 in less degree1 ,jupiter also4 ,but in neither case is this departure from fullness sufficient to have any appreciable effect on the planet's brightness1 and1 moreover1 it does not occur when the planet is in the most favorable position for us to see it4 ,at opposition1 therefore1 we always have the full face of the planet presented to us2 and being1 as we then are1 on the same side of the sun with it1 we are ninety-three millions of miles 7our distance from the sun7 nearer to it than the sun is4 ,being1 when in opposition1 exactly opposite the sun1 the planet rises just as the sun sets4 ,after opposition it rises a little earlier each evening1 and is higher up in the sky at each succeeding sunset4 ,when we find it just half-way between the eastern and the western horizon at sunset1 it is at quadrature4 ,after quadrature it appears nearer and nearer the western horizon each evening at sunset1 until it finally is too near the sun to be visible4 ,it is then traveling in that part of its orbit which is beyond the sun from us4 ,from opposition to this situation it has been an evening star4 ,when a superior planet is in line with the sun and the earth1 and is on the far side of the sun from us1 it is said to be in conjunction1 and we are then one hundred and eighty-six millions of miles1 or twice our distance from the sun1 farther from it than we are when it is in opposition4 ,but besides being placed at so much greater distance from it1 we have in this situation the bright sun excluding the planet from our view4 ,it will be readily seen1 therefore1 why the superior planets are in so much better position for us to see them in opposition than at conjunction4 ,from conjunction to opposition the planet is west of the sun1 and will be below the horizon at sunset1 and will rise some time during the night4 ,at first it will appear just before sunrise as a morning star1 but will gradually rise earlier each night until1 when it reaches opposition again1 it will rise just as the sun sets4 ,half-way between conjunction and opposition it is again at quadrature4 ,from opposition to conjunction the planet will be east of the sun and above the horizon at sunset4 ,when a planet is in conjunction with the sun1 it passes the meridian1 or the point half-way between rising and setting1 about noon1 and is above the horizon with the sun during the day4 ,when it is in opposition it passes the meridian about midnight1 and is above the horizon during the night4 ,when it is at quadrature and moving toward conjunction1 it passes the meridian about six o'clock in the evening1 and may be seen in the western half of the sky during the early evening1 and will set before midnight4 ,when it is at quadrature and moving toward opposition1 it will rise some time between midnight and sunset1 and will be in view in the east during a part of the first half of the night4 ,the nearer it is to opposition1 the earlier in the evening it rises and the longer it may be seen4 ,the main movement of the superior planets among the stars is from west to east1 and this is known as their direct motion4 ,but not far from opposition they seem to hesitate1 then move more slowly1 then finally stop1 remain stationary for a time1 turn back on their tracks1 and start off in the opposite direction4 ,this is their retrograde motion4 ,they do not continue in it as long as in the direct motion2 but after a comparatively short time they again hesitate1 go more slowly1 stop1 remain stationary1 then turn back and swing off in the original direction1 and continue to move in this direction until they are again approaching opposition4 ,it is exactly in the middle of this sweep toward the west that the planet is in opposition4 ,close observation will show that the superior planets also make something of the same sort of a loop in their path among the stars that the inferior planets make1 and for the same reason4 ,the only difference is that when a superior planet is retrograding we are passing it1 and when an inferior planet retrogrades it is passing us4 ,in giving this rather rough outline of the way the planets in general move among the stars1 reaching in their wanderings these various positions with relation to the sun and the earth1 the intention is only to fix some definite situations from which to consider the movements of the individual planets4 ,when we come to know each planet as an individual1 and to follow it as it comes and goes in the heavens1 and to watch its ever-wonderful changes in brilliancy1 these situations will have a much more definite meaning to us and a relatively greater interest and importance4 ,the planets as they appear to us all move along pretty much the same path2 but each has its own way of gracing this path1 and each its particular manner of changing in aspect4 ,,ix ,,the ,,path ,,of ,,the ,,planets ,though the planets are called wanderers1 they are not by any means the vagrants that the name might imply4 ,they have a fixed course among the stars from which they never deviate1 and the ways of all of them1 and also of the sun and the moon1 are confined to a comparatively narrow strip in the sky4 ,that strip is called the zodiac4 ,it is only sixteen degrees wide1 and extends like a narrow band all the way around the heavens4 ,it lies so that it is always easy to observe2 and1 being so limited1 very little observation is necessary to become familiar with every part of it4 ,within its limits all the movements of the sun1 the moon1 and the planets take place4 ,through the center of it is the ecliptic1 the great circle that marks the annual apparent path of the sun through the heavens4 ,it is the standard circle from which we measure the paths of the moon and the planets4 ,whatever degree their courses vary from the ecliptic is what we call the inclination of their orbits4 ,if the plane of the orbit of a planet is tilted away from the ecliptic1 the planet will travel half the time on one side of it1 and half the time on the other4 ,the orbits are1 in fact1 very little inclined to the ecliptic1 and all but one of the planets may always be found within three degrees of it1 most of them nearer than this4 ,the one exception is ,mercury1 which is sometimes as much as seven degrees from this central line of the zodiac1 but ordinarily it is not so far as this4 ,uranus is so nearly on the ecliptic that an ordinary observer would not notice the deviation1 and particularly as ,uranus can rarely be detected with the naked eye1 and can never be thus followed4 ,of the four planets which are the ones we ordinarily see1 ,mars and ,jupiter are never as much as two degrees from the ecliptic1 ,saturn never more than two and a half degrees1 and ,venus never more than about three degrees4 ,they are all usually nearer than these outside limits4 ,the greatest distance of the moon from the ecliptic is about one and a half degrees4 ,hence1 with the exception of ,mercury1 all the planets and the sun and the moon travel in a path six degrees wide1 which is only one degree wider than the distance between the pointers as we see them in the ,great ,dipper4 ,the fact that the zodiac is sixteen degrees wide1 or eight degrees on each side of the ecliptic1 is due only to a very generous allowance for the vagaries of ,mercury1 which he really does not quite need4 ,for ,mercury is always as much as twice the breadth of the moon1 or one degree1 inside of the zodiac1 and usually more than that4 ,because the earth is tilted on its axis twenty-three and a half degrees from the perpendicular1 the ecliptic runs through the heavens in an oblique circle1 crossing the line of the equator at two points called the vernal and autumnal equinoxes4 ,the equator in the heavens is the great circle extending around the celestial sphere half-way between the north and south poles4 ,it is always practically ninety degrees from the north star1 and the points at which the ecliptic intersects it are called the equinoxes4 ,these are the only two points on the ecliptic that are just ninety degrees from the pole4 ,the word equinox is derived from equus 7equal7 and nox 7night71 and when the sun is at the equinoxes the days and nights are of equal length4 ,from the vernal to the autumnal equinox the line of the ecliptic is north of the equator1 and hence high in the sky1 reaching its highest point midway between the equinoxes4 ,it then crosses the equator again and runs obliquely south to the lowest point in its path1 and then curves northerly back to the vernal equinox4 ,the vernal equinox is the point at which the sun arrives when spring begins4 ,this results in the sun's being north of the equator from spring until autumn1 and south of it from autumn to spring4 ,as the part of the zodiac that we can see best at night is that opposite where the sun is1 so in summer1 when the sun is high1 we see best the part of the zodiac which is low in the southern skies in the evening2 and in the winter1 when the sun is in the southern half of his journey1 the part of the zodiac best seen by us is high in the heavens4 ,no part of it1 however1 is ever as high as the zenith1 or directly overhead1 and no planet is ever seen as far north as the zenith in any place whose latitude is more than twenty-three and one-half degrees from the equator4 ,to know the paths of the planets it is necessary to know only twelve constellations out of the seventy or more in the entire heavens2 but it is difficult to imagine any one's learning these twelve without becoming interested in and more or less acquainted with many of the splendid stars and constellations that lie on each side of them4 ,the larger one's acquaintance is with the appearance of the skies as a whole1 the easier1 naturally1 it will be to distinguish the planets from the stars1 and to follow their courses4 ,but the planets themselves may be intimately known quite apart from any but the twelve constellations forming the zodiac4 ,happily1 among them we shall find some of the most beautiful constellations in the heavens1 and some of the most splendidly brilliant first-magnitude stars4#a #a ,the reader will find fuller descriptions of the stars in the zodiac in ,the ,friendly ,stars1 by the author of this book4 ,the twelve constellations of the zodiac are as follows3 ,pisces1 the ,fishes4 ,aries1 the ,ram4 ,taurus1 the ,bull4 ,gemini1 the ,twins4 ,cancer1 the ,crab4 ,leo1 the ,lion4 ,virgo1 the ,virgin4 ,libra1 the ,scales or ,balance4 ,scorpio1 the ,scorpion4 ,sagittarius1 the ,archer4 ,capricornus1 the ,goat4 ,aquarius1 the ,water-,carrier4 ,we shall begin at the point of the vernal equinox to trace the line of the ecliptic through these constellations1 and that line will mark for us the path of the sun1 the moon1 and all the planets4 ,it is convenient to begin at this point1 because it is where the sun crosses the equator in the spring1 and hence it is at the beginning of that part of the ecliptic which lies north of the equator4 ,the point of the vernal equinox is now situated in the constellation ,pisces4 ,it is not marked by any bright star1 but is not very difficult to find4 ,it marks the point on the eastern horizon where the sun rises about ,march #bast1 and about the #bast of ,september it is on the eastern horizon exactly opposite that point in the western sky where the sun sets4 ,it is always ninety degrees from the pole1 and if one chances to know the constellation ,cassiopeia1 which is shaped like a chair and is on the opposite side of the pole from the ,big ,dipper1 one can locate the vernal equinox by drawing a line from the pole-star through the star which marks the lower part of the front of the chair1 and extending it until it is ninety degrees long4 ,the ninety degrees can be estimated by using the distance between the pointers in the ,dipper 7which is five degrees7 as a measure4 ,the star mentioned in ,cassiopeia is about thirty-two degrees from the north star4 ,illustration3 ,,map ,,showing ,,the ,,constellations ,,of ,,the ,,zodiac ,,and ,,the ,,line ,,of ,,the ,,ecliptic ,,running ,,through ,,them ,the paths of all the planets1 save one1 lie always within three degrees of the ecliptic4 ,having once learned the constellations of the zodiac and1 approximately1 the line of the ecliptic1 it is not necessary for the ordinary observer to keep in mind the exact location of the vernal equinox4 ,it is1 however1 an important point for the student of mathematical astronomy4 ,beginning at this point1 the ecliptic runs through ,pisces in a northeasterly direction for about thirty degrees to ,aries1 the second constellation of the zodiac4 ,,aries ,aries is best seen in the autumn when the sun is in the opposite side of the heavens4 ,it is marked by a small acute-angled triangle1 with the apex toward the north and the brightest star of the three at the apex4 ,this star is called ,hamal1 and1 while not a first-magnitude star1 is a rather bright one of the second magnitude2 and the triangle itself is very distinctly marked4 ,it is the only group of stars by which to distinguish ,aries1 and it is sometimes confused with the little constellation called ,triangulum1 which lies just west of it1 or above it1 as it rises4 ,with this in mind1 ,triangulum may be made to serve as an identifying mark4 ,they both rise just a trifle north of the exact east early in the evenings of late ,september and ,october4 ,triangulum rises first1 with its apex toward the south4 ,in less than an hour the triangle of ,aries arrives with its apex pointed north4 ,the ecliptic runs about five degrees below this triangle1 and its path across ,aries is about twenty-eight degrees long4 ,when one sees any very bright star in ,aries1 one may be sure it is a planet4 ,the sun is in ,aries from ,april #afth to ,may #acth4 ,during the summer this constellation is not visible in the early evening2 but it may be seen every evening from ,september to ,april1 drawing all the time nearer to the sun1 and setting earlier each evening until the sun blots it out4 ,from this constellation the ecliptic runs into ,taurus1 the third zodiacal constellation4 ,,taurus ,this constellation may be identified by the brilliant first-magnitude star ,aldebaran1#b and the misty ,little ,dipper of the ,pleiades4 ,it is a very beautiful and large constellation4 ,about an hour and a half after the triangle of ,aries has risen1 the soft-twinkling cluster of tiny stars which form the ,pleiades comes above the eastern horizon1 and about an hour later a ,v-shaped cluster of brighter stars1 with a very bright-red one at the end of the lower half of the ,v1 appears4 ,this last cluster is the ,hyades1 and the bright star is ,aldebaran4 #b ,see 8,aldebaran0 in ,the ,friendly ,stars4 ,by these two clusters we may know the constellation4 ,the ecliptic passes across ,taurus about four degrees east of the ,pleiades1 and about seven degrees west of ,aldebaran4 ,the planets in passing through this region often come very close to the ,pleiades1 and parts of the group are sometimes occulted by the moon4 ,taurus is conspicuous in the eastern evening sky from ,september until nearly ,january4 ,from that time on until ,may it may be seen in the evening1 high up in the sky1 a little farther west each evening1 until it disappears in ,may4 ,among the four planets that we most see ,mars is the only one that resembles ,aldebaran in color4 ,they are both reddish1 but ,mars is always west of ,aldebaran near the line of the ecliptic1 and also it does not have the same twinkling face that ,aldebaran shows2 hence the star and the planet need never be confused4 ,mercury1 it is true1 is reddish and twinkles1 but so seldom needs to be taken into account that it will not be troublesome4 ,the other planets when in ,taurus will proclaim themselves by their color and size4 ,there is no very bright star in ,taurus except ,aldebaran1 which has been described4 ,any bright star north of it in the constellation is sure to be a planet4 ,through ,taurus the line of the ecliptic runs in a northeasterly direction1 and about fifteen degrees east from ,aldebaran it passes about half-way between two fairly bright stars which mark the tips of the horns of ,taurus1 and from there on into the fourth constellation4 ,,gemini ,gemini lies northeast of ,taurus1 and is outlined by a box-shaped figure something more than twenty degrees long and about five degrees wide4 ,the two stars marking the end of it farthest from ,taurus are the famous twins1 ,castor and ,pollux4#c ,pollux is a first-magnitude star1 and ,castor is very little less bright4 ,they are both very charming stars1 and too conspicuous to escape easy identification4 ,castor is greenish in tint1 and rises between an hour and a half and two hours later than ,aldebaran4 ,about fifteen minutes after he appears1 ,pollux1 with a yellow-tinted face1 comes up over the eastern horizon4 ,they rise about thirty degrees north of the exact east4 ,the ecliptic has reached its highest point north just after passing through the horns of ,taurus4 ,it then runs through ,gemini in a southeasterly direction1 curving diagonally across the main figure and passing five or six degrees below ,pollux4 ,gemini can be seen from ,october to early ,june4 ,it is particularly charming in ,may in the northwest just after sundown1 and when any of the planets are going along this part of their path at that season1 they are sure to win one's interest and admiration4 #c ,see 8,the ,heavenly ,twins0 in ,the ,friendly ,stars4 ,,cancer ,after leaving ,gemini the ecliptic passes through the small constellation ,cancer4 ,its way runs southeasterly for about twenty degrees1 passing just south of a charming little cluster of stars which can be dimly seen with the unaided eye1 but comes out brilliantly with an opera-glass4 ,it is called ,prsepe1 or the ,bee-hive1 and is the only object to attract attention in ,cancer4 ,fortunately1 it is so situated as to mark the line of the ecliptic through the constellation4 ,the ,bee-hive rests almost exactly on the ecliptic4 ,,leo ,leaving ,cancer1 the sun enters ,leo1 a large1 well-marked constellation known to many persons by the conspicuous figure in it of a sickle4 ,at the end of the handle of the ,sickle is ,regulus1 one of the bright first-magnitude stars4 ,a little more than fifteen degrees east of the ,sickle the rest of the constellation is marked by a large triangle formed by three rather bright stars4 ,both of these figures are well marked and easily seen1 making ,leo one of the easiest of the constellations to find4 ,the sun crosses it in a southeasterly direction which leads straight across ,regulus4 ,the star is often occulted by the moon1 and by the sun also1 though that we cannot see on account of the blinding light of the sun4 ,leo is visible nearly eight months in the year4 ,it is in the eastern sky early in the evening in the winter1 and shines all night from late in ,december until ,april4 ,in ,may and ,june it is traveling westerly1 but high up in the sky4 ,in ,july it is in the western sky in the evening4 ,the sun passes through it from ,august #gth to ,september #adth4 ,regulus is a white star1 and twinkles violently1 so that it is easily distinguished from any planet that is passing near it4 ,in the other part of the constellation the path of the planets runs about ten degrees below the triangle4 ,,virgo ,when the sun has passed ,leo it enters the largest of all the constellations1 ,virgo1 and passes through it in forty-five days1 from ,september #adth to ,october #bith4 ,the constellation is far from rich in bright stars2 but one may find the ecliptic1 or path of the sun1 by following a curved southeasterly line from ,regulus about sixty-five degrees until it reaches ,spica1#d a very bright first-magnitude star in this comparatively starless region4 ,if there is any doubt about ,spica1 it may be found by following the curve of the handle of the ,big ,dipper about thirty degrees1 which brings one to the splendid ,arcturus1 and then about thirty degrees farther on1 which points one to ,spica4 #d ,see 8,spica0 in ,the ,friendly ,stars4 ,eight or nine days after entering ,virgo the sun crosses the equator at the autumnal equinox1 and the rest of the ecliptic lies farther south4 ,spica is about ten degrees south of the equator4 ,spica is in the east during the early evenings in ,april and ,may2 throughout ,june and ,july it may be seen in the south during the evening4 ,in ,october it sets at about the same time as the sun4 ,the autumnal equinox1 or the point where the ecliptic crosses to the south of the equator1 is in ,virgo1 and lies about fifteen degrees northeast of ,spica4 ,,libra ,libra is the next zodiacal constellation1 and it is a small one4 ,the sun passes through it in about twenty-three days4 ,it may be known by four fairly bright stars which form a more or less imperfect square4 ,the ecliptic passes along the southern edge of this figure4 ,during the summer and early autumn1 ,libra is best seen4 ,it is then passing across the southern sky1 drawing nearer the west each evening4 ,a planet passing across this constellation would always be easy to identify1 since it would always be so much brighter than any star in this region4 ,the sun enters ,libra about ,october #bith1 and it is not visible in the evening during the rest of the year4 ,,scorpio ,it is a joy to know ,scorpio1 quite aside from its connection with the path of the planets4 ,it is a brilliant constellation1 best seen during the summer and autumn1 as it passes across the southern sky4 ,it is the most southerly of any of the constellations of the zodiac2 but the ecliptic passes through only a very small portion of the northern part of it1 so the sun does not reach the most southerly point in its path while it is in this constellation4 ,scorpio may be best identified by its brilliant deep-red star ,antares1#e which is supposed to lie in the heart of the ,scorpion4 ,the whole figure makes a splendid serpent-like sweep toward the southern horizon1 and is one of the most conspicuous objects just west of the ,milky ,way in the south in summer4 #e ,see 8,antares0 in ,the ,friendly ,stars4 ,the line of the ecliptic runs about three degrees north of ,antares2 hence the planets in their course sometimes pass very near it4 ,jupiter has been in that region all this year 7#aiab71 and will not be far from there the early part of #aiac4 ,mercury and ,mars both have something the color of ,antares2 but this is not likely to result in any confusion4 ,the star is always there1 and in the same relative situation with reference to the other stars4 ,when ,mars is there1 it will always be above the star4 ,mercury can seldom be seen when he is in ,scorpio4 ,if he is in greatest elongation while there1 he will still be near the sun1 and the sun1 as seen from the middle latitudes1 is so far south and so near the horizon when in that part of the ecliptic that the situation will not be favorable for seeing the planet4 ,farther south1 and particularly in high altitudes1 ,mercury could be well seen in ,scorpio1 but if the position of ,antares is kept in mind1 ,mercury will easily be recognized as a stranger in the constellation4 ,the sun enters ,scorpio about ,november #bast1 and the constellation then ceases to be visible in the evening sky until the following ,may4 ,it is in its greatest glory during the summer and early autumn4 ,,sagittarius ,when the sun leaves ,scorpio it crosses the ,milky ,way into ,sagittarius1 and there reaches the lowest point in its path1 twenty-three and one-half degrees south of the equator4 ,this constellation is best distinguished by the little 8milk dipper10 which is easily seen turned upside down just at the eastern edge of the ,milky ,way4 ,the line of the ecliptic runs a little north of it4 ,the constellation may be best seen during about the same months that ,scorpio is visible4 ,the sun enters it1 and it passes out of view about the middle of ,december4 ,,capricornus ,,and ,,aquarius ,from ,sagittarius the ecliptic runs in a northeasterly direction through a region in which there are no very bright stars1 nor any very distinct outlines of figures4 ,the two constellations through which it passes are ,capricornus and ,aquarius4 ,it then runs a few degrees into ,pisces1 and there reaches the vernal equinox1 where we began to trace its course4 ,although one cannot trace the line of the ecliptic with the same definiteness in this region as in one where there are bright stars to mark the way1 yet when a planet is in this part of its path it is perhaps more conspicuous and more easily recognized than when it appears in any other part of the sky1 because of the very absence of other bright bodies4 ,these constellations comprise all that region running from the ,milky ,way east to the vernal equinox4 ,it is a part of the heavens easily seen during the pleasant evenings of summer and autumn1 and if a planet is crossing it during those seasons it is particularly well placed for observation4 ,the two brightest stars in ,capricornus are of the third magnitude1 and lie about twenty degrees northeast of the 8milk dipper40 ,the ecliptic runs just under them4 ,through ,aquarius it runs six or seven degrees above a waving line of faint stars1 which are supposed to represent the water that ,aquarius is pouring from his urn4 ,if one will take the trouble to trace the line of the ecliptic through the sky1 and remember that it lies exactly in the center of the zodiac1 and that the planets are1 therefore1 within a very few degrees of it1 one will have no trouble in keeping track of them4 ,the mere knowing of these constellations is in most cases sufficient1 since the planets will disclose their identity in other ways than by position merely4 ,the signs of the zodiac are somewhat different from the constellations4 ,they are simply twelve equal divisions of thirty degrees each1 making in all three hundred and sixty degrees1 which is the whole number of degrees in any circle4 ,they are so divided for convenience in scientific observation and reckoning4 ,about two thousand years ago the signs and the constellations in the main coincided1 and they still bear the same names4 ,the point of the vernal equinox was then at the beginning of the sign and the constellation ,aries4 ,but1 owing to certain motions of the earth1 this point shifts backward1 or toward the west1 about one degree every seventy-two years4 ,in two thousand years it has shifted about twenty-eight degrees1 until now the sign ,aries1 with the vernal equinox at its western boundary1 lies almost wholly in the constellation ,pisces1 the sign ,taurus corresponds approximately to the constellation ,aries1 and so on around the circle4 ,it is important to know this in following the planets1 because all almanacs and scientific publications deal mainly with the signs of the zodiac1 and not with the constellations4 ,when a planet's place is said to be in ,aries1 ,taurus1 or ,gemini1 one will find it in ,pisces1 ,aries1 or ,taurus1 respectively4 ,and so it is with all the other signs2 they are each one constellation behind the one bearing the same name4 ,and this is why1 beginning with the vernal equinox1 ,pisces is the first constellation in the zodiac1 while ,aries is the first sign4 ,the following is a list of the signs of the zodiac1 with the corresponding constellations4 ,the symbols given in parenthesis are the ones used for these signs in all almanacs3 ,,sign ,,constellation ,aries 77 ,pisces ,spring ,taurus 77 ,aries signs ,gemini 77 ,taurus ,cancer 77 ,gemini ,summer ,leo 77 ,cancer signs ,virgo 77 ,leo ,libra 77 ,virgo ,autumn ,scorpio 77 ,libra signs ,sagittarius 77 ,scorpio ,capricornus 77 ,sagittarius ,winter ,aquarius 77 ,capricornus signs ,pisces 77 ,aquarius#f #f ,for those who find rhymes an aid to memory1 the following list may prove useful3 ,this is the way the spring begins3 ,first ,aries1 then ,taurus1 then the ,heavenly ,twins4 ,the first summer sign is the one we call ,cancer2 ,the next two to ,leo and ,virgo will answer4 ,then autumn brings ,libra and bright ,scorpio1 ,and next ,sagittarius1 with his strong bow4 ,capricornus then ushers the winter in1 ,and near old ,aquarius the year we begin4 ,pisces comes next1 and then winter is done2 ,and with ,aries's approach1 a new spring is begun4 ,these are the signs2 but bear this well in mind3 ,the sun lags in one constellation behind4 ,when his place is ,aries1 we'll find him in ,pisces2 ,when in ,taurus he should be1 in ,aries he stays4 ,if ,gemini's his place1 and to find him our wish is1 ,we must look back in ,taurus to see his bright rays4 ,and so through the year1 whatever his place is1 ,the bright group behind is the one that he graces4 ,x ,,mercury ,while ,mercury is one of the five planets that can be seen with the naked eye1 it must be confessed that he does not play any important part in the great spectacle of nature as we see it in the skies4 ,but in a certain way this only adds to our interest in him4 ,the very rarity of his appearances and the difficulty of finding him give a zest to the search1 and a sense of achievement1 when it is successful1 that one does not have with regard to the other planets4 ,it is something akin to the feeling one has when1 after a long tramp to some secluded recess in the woods in search of the shy pink lady's slipper1 a splendid specimen of that lovely flower suddenly comes into view hanging gaily on its stalk1 ready for the use of whatever fairy foot may tread its shady groves4 ,then1 too1 the spring o' the year is the most likely time to see ,mercury in the evening sky4 ,he comes into his best position for this view of him just when the evenings are growing longer and milder and one begins to hunger for outdoor things1 so that the quest of him at that time has the gladness that goes with our first excursions into the open after a winter's housing1 whether it be in search of flowers1 or birds1 or stars1 or simply the general loveliness of everything that belongs to the beginning of the outdoor season4 ,the reason ,mercury is so elusive is that he is always very near the sun1 and in consequence his light is dimmed by the brighter light shed by that luminary until it is well below the horizon2 and after the sun has set1 the planet is so involved in the usual haziness of the atmosphere near the horizon that the conditions must be very favorable in order to see him4 ,though there are recorded observations of ,mercury as far back as nearly three hundred years before ,christ1 yet some of the older of the modern astronomers1 before the days of the perfected telescope1 are said not to have seen him at all2 and the most important observations of the planet nowadays are made in broad daylight1 when it is higher up in the skies and free from the mists of the horizon4 ,this can be done by means of a powerful telescope1 because it is possible in this way to shut off the light of surrounding bodies2 but1 of course1 the conditions are not as favorable as if midnight observations could be made4 ,still1 if one knows just when and where to look1 ,mercury can be seen with the naked eye at least once or twice a year1 and sometimes oftener than this1 especially if one chances to live in one of the ,western ,states1 where the air is very clear and the situation in latitude and altitude more favorable than1 say1 in ,new ,england1 or in the middle ,atlantic ,states4 ,in our ,northern ,states1 and in the whole of ,england1 this planet is more difficult to see1 because of the longer twilight in northern latitudes1 and also because the line of the ecliptic1 over which it passes1 seems there lower down in the skies1 while in the far ,south1 say in ,cuba or ,porto ,rico1 the twilight is shorter1 the ecliptic runs high in the sky1 and the situation is favorable for a good view even though the atmosphere is no clearer than it is farther north4 ,,when ,,and ,,where ,,to ,,find ,,mercury ,mercury is never more than twenty-eight degrees from the sun1 and is brightest when the distance between them is somewhere near twenty-two degrees1 or about four times the distance between the pointers in the ,big ,dipper4 ,the direction in which to search for him must always be along the line of the ecliptic obliquely above the sun4 ,since his orbit is inclined seven degrees to the ecliptic1 he will be some place within seven degrees of this line1 on one side or the other4 ,within this narrow strip in the sky1 fourteen degrees wide and twenty-eight degrees long1 ,mercury will be found whenever he is visible at all4 ,and this strip may be further shortened by at least twelve degrees2 for when the planet is nearer than that to the sun it is futile to attempt to see him with the naked eye1 save in very exceptional conditions4 ,the five degrees between the pointers will serve as an aid in measuring these distances4 ,we can never see ,mercury with the naked eye except when he is near one elongation or the other2 and even then he is visible only about an hour after the sun is down in the evening or about an hour before it rises in the morning4 ,three times each year he appears in the evening for more or less than a week1 according to the situation of the observer1 and three times a year he is visible in the morning for about the same length of time4 ,but1 owing to his position with relation to us1 the evening exhibit that comes in the spring is the most favorable one for a good view of him1 and the morning appearance that is most favorable is the one that comes in the autumn4 ,the mean synodic period of ,mercury is about one hundred and sixteen days1 or a little less than four months4 ,that is1 he returns to greatest eastern elongation and can be seen in the evening sky about every one hundred and sixteen days1 and the same length of time elapses between his appearances in the morning sky at greatest western elongation4 ,but this mean synodic period is made up of synodic periods varying in different revolutions from one hundred and five to one hundred and thirty-four days4 ,so1 though one may mark the dates at which the various positions of the planet occurred during any one revolution1 one cannot so easily determine the exact time at which he will be found in the same positions at the next revolution2 that is1 whether the revolution will take place in less or more than one hundred and sixteen days4 ,the earth and the planet are each traveling at varying rates of speed1 according as they are near the sun or farther from it1 and obviously it is a situation that requires careful mathematical work to compute4 ,the almanac must be referred to for the exact date4 ,but1 lacking an almanac1 one will generally find that ,mercury will return to the same position relative to the earth and the sun within a few days of his mean synodic period4 ,three periods1 however much they may vary individually1 are almost always equal to three hundred and forty-eight days1 or three times the mean period4 ,this is seventeen days less than a year4 ,hence1 if one is lucky enough to have seen ,mercury at eastern elongation one spring1 and will look the next year about seventeen days earlier1 the planet will be found a little to the east 7about fifteen degrees7 of where he was when first seen the year before4 ,he is there in the same position with relation to us and the sun that he had the preceding spring1 but in a slightly different relation to us and the stars1 because the sun lacks seventeen days of having completed its apparent yearly journey around the zodiac4 ,it must still go through about one half of a constellation4 ,when ,mercury shows himself at eastern elongation1 he may be seen in the west as an evening star for somewhere near a week1 each evening drawing nearer to the sun4 ,when he disappears from view he passes between us and the sun1 and about four weeks later appears in the morning sky before the sun rises4 ,under favorable conditions he is again visible for a week or more2 and then1 again approaching the sun1 he can be seen no more for about ten weeks1 during which time he passes through superior conjunction on the other side of the sun from us and comes back to eastern elongation4 ,thus we can get1 under very favorable conditions1 six short views of ,mercury during the year--three in the evening and three in the morning4 ,so many views1 however1 are rarely secured by any but the professional observer4 ,the circumstances may well be considered felicitous if one succeeds in getting a glimpse of him once or twice a year--at his favorable situation in the evening in the spring and the morning in the autumn4 ,the sight of him1 though1 is truly worth a little inconvenience--even to the extent of facing a cold evening wind in the very early spring or getting out of a comfortable bed before dawn during the first cool mornings of autumn4 ,it is hardly possible to say exactly where one can find ,mercury at all times during a long succession of revolutions4 ,moreover1 it is not necessary4 ,these computations are made anew each year by experts in the employ of the government1 and the result is published in the ,nautical ,almanac4 ,from there it finds its way into all almanacs1 so it is easy of access to any one4 ,in the almanacs ,mercury is represented by the sign 774 ,it is a conventionalized form of the caduceus1 or wand1 carried by the god ,mercury as a symbol of his power4 ,the next seven eastern and western elongations of ,mercury occurring after the publication of this book are as follows3 ,eastern ,elongation ,western ,elongation 7,evening ,star74 7,morning ,star74 #ah ,november1 #aiab4 #bg ,december1 #aiab4 #aj ,march1 #aiac4 #bd ,april1 #aiac4 7,favorable for viewing47 #g ,july1 #aiac4 #bb ,august1 #aiac4 7,favorable for viewing47 #a ,november1 #aiac4 #aj ,december1 #aiac4 #bb ,february1 #aiad4 #f ,april1 #aiad4 7,favorable for viewing47 #ah ,june1 #aiad4 #e ,august1 #aiad4 7,favorable for viewing47 #ae ,october1 #aiad4 #bc ,november1 #aiad4 ,,distance ,,and ,,brightness ,of all the planets ,mercury is nearest the sun4 ,his average distance is thirty-six million miles4 ,he is nearly eighty times nearer than ,neptune1 the outermost planet1 and more than two and one-half times nearer than we are4 ,but his orbit departs so far from being a circle that his distance from the sun varies as much as fifteen million miles4 ,when he is nearest the sun1 or in perihelion1 he is only twenty-eight million miles from it2 when he is farthest1 or in aphelion1 his distance is forty-three million miles4 ,there is even greater variation in his distance from us4 ,the difference between his least possible and his greatest possible distance from us is as much as eighty-nine millions of miles4 ,for the earth has an elliptical orbit as well as ,mercury1 and when we are at perihelion1 which occurs in the winter1 we are three millions of miles nearer to the sun than we are in mid-summer4 ,if ,mercury chances to be then at his greatest distance from the sun1 and also at inferior conjunction1 or between us and the sun1 he is only forty-seven millions of miles from us4 ,if1 when we are farthest from the sun1 he also is at his greatest distance from it1 and is in superior conjunction1 or on the other side of the sun from us1 he is one hundred and thirty-six millions of miles from us4 ,these changes in distance from the earth have much to do with ,mercury's changes in apparent brightness to us4 ,at his brightest1 when he appears at greatest elongation and we can see him without a telescope1 he is brighter than ,arcturus1 the brilliant first-magnitude star in ,botes1 that swings over us nightly from early spring to late autumn4 ,when seen with the naked eye1 he is also red in color1 somewhat like ,arcturus2 but through a telescope he is dull silver1 like the moon1 or even more ashy in his paleness4 ,as he goes farther and farther from us he becomes dimmer and dimmer and can be followed only with a telescope until1 even with this aid to vision1 he is lost in the rays of the sun at superior conjunction4 ,his apparent diameter as mathematically measured varies from five seconds1 when he is farthest away1 to thirteen seconds1 when he is nearest4 ,when he is at his nearest possible distance from us1 light travels from ,mercury to us in a little more than four minutes4 ,at his greatest possible distance we could not receive the waves of light that he sends out in less than twelve minutes4 ,as a matter of fact1 we do not receive them at all1 for1 as we have seen1 he is invisible when at his greatest possible distance from us1 being then on the far side of the sun4 ,another cause of ,mercury's apparent change in brightness is due to the fact that1 in common with ,venus1 he goes through phases from crescent to full like the moon4 ,this is1 as we have seen1 a result of his shining only by reflected light and of his orbit's being between ours and the sun4 ,if he shone by his own light1 he would be at his nearest approach to us a very brilliant body indeed4 ,as it is1 his dark side is turned toward us when he is nearest1 and when his full face is illuminated he is on the far side of the sun4 ,we see half of his face when he is at greatest elongation2 but he is brightest when we see less than half1 because he is then nearer to us1 and the difference in distance more than compensates for the difference in illumination4 ,these phases cannot be seen with the naked eye1 but it requires only a small telescope to show them1 and a very charming little moon-like body ,mercury is when we see them4 ,his horns point toward the east when he is coming toward us and nearing inferior conjunction1 and when he is backing away from us and going toward greatest western elongation they point toward the west4 ,it was through the blunting of one of these horns when the planet was in certain positions that a mountainous surface was suspected1 so great is the significance of small details in observations4 ,as a mere place from which to view the other bright bodies ,mercury would be far superior to the earth4 ,he not only has the sun nearly seven times larger in appearance at its mean distance than we see it1 but1 being himself nearest the sun1 all the other planets are outer planets in relation to him1 and all have their discs fully illuminated4 ,the earth and the moon1 as seen from ,mercury1 would show as a splendid pair of stars circling about each other1 the earth more brilliant than any first-magnitude star1 and the moon of the third magnitude1 or about as bright as ,phecda1 the star at the bottom of the bowl of the ,big ,dipper1 just under the beginning of the handle4 ,the earth would show a disc of about twenty seconds1 and the moon one of about eight seconds1 with a distance between them of about #hga seconds4 ,some idea of what this distance is may be had if one knows ,mizar1 the star at the bend of the handle of the ,dipper1 and its tiny shining attendant1 ,alcor4 ,these two stars are #gjh seconds apart4 ,the distance between them is about equal to one-third of the diameter of the moon as measured from the earth4 ,it does not appear to be nearly so much as that1 and some persons have difficulty in separating the two stars2 but the moon is not only inconstant but deceptive1 and owing to its brilliancy seems always proportionately larger than it really measures4 ,venus would appear from ,mercury as much as four times as large as she seems to us--a veritable little moon1 and always full1 her size varying slightly as ,mercury speeded back and forth from the farthest to the nearest point in his orbit1 changing the extreme of the distance between them from one hundred and ten million to less than twenty-four million miles4 ,if ,mercury needed a moon1 he could well find some consolation for his lack of it in the presence of the lovely ,venus in his sky4 ,,mercury',s ,,size ,,and ,,the ,,consequences ,,of ,,it ,mercury is the smallest of all the major planets4 ,his diameter is about three thousand miles4 ,it is only about nine hundred miles greater than that of our moon4 ,the surface of ,mercury is only one-seventh that of the earth1 and his volume only one-twentieth4 ,jupiter and ,saturn each have a satellite that is considerably larger4 ,mercury would make a splendid satellite or a giant asteroid1 but as a planet seems hardly to have had a fair chance in life4 ,for being a small planet means something more than being constructed on smaller lines than some others are4 ,it means a difference in physical development4 ,it means less power to hold the gases that compose an atmosphere1 which is the cover that shields the planets from the too burning rays of the sun and keeps their internal heat from radiating too quickly into space4 ,it means less power to resist the tidal friction that the parent body uses as a brake to retard rotation4 ,it means a shorter time of activity in life1 and a long1 dull1 monotonous old age4 ,the nucleus that was detached from the great spiral1 or the portion of nebula that was separated in whatever way from the parent body1 to form ,mercury chanced to be a small one4 ,being small1 it was unable to add materially to its mass by attracting other particles to it through the power of gravitation1 as a larger planet might do1 and thus ,mercury was doomed to develop with the limitations that nature's law has decreed as inevitable in the small bodies of our solar system1 be they planets1 satellites1 or asteroids4 ,of these limitations the first and most far-reaching in its effect is the feebleness of its force of gravity1 or power to attract other bodies4 ,mercury's force of gravity is small4 ,it is smaller than that of any of the other planets4 ,it is a little less than one-quarter that of the earth4 ,the same weight of feathers that would compose a pillow here would make a whole feather bed on ,mercury4 ,any object weighing one hundred pounds here would weigh only twenty-four there4 ,the materials composing our earth and all the planets are held together only by the force of gravity4 ,the air we breathe would dart off into space with almost incredible fleetness if the earth had not sufficient gravitative force to hold it4 ,its particles are struggling all the time to get beyond this power4 ,the lightest of them do get beyond it and are lost1 and the less power we have to hold them the sooner they leave us4 ,the greater the mass of a body1 the rarer the gases it can hold in its atmosphere1 for this mysterious force which pulls everything toward the center of a planet depends upon its mass1 or the quantity of material in it4 ,the planet may be very large because it is very much expanded4 ,it may be gaseous even1 and its mass would then be very small in proportion to that of a solid body of the same size4 ,as it condenses1 the particles draw closer and closer together1 the density increases2 but the mass is the same4 ,it is only the size that diminishes4 ,so a planet with a small mass starts out in life with a disadvantage4 ,it not only has little power to grow by drawing in particles from its environment1 but also has little power to hold such as by their nature are volatile and swift of motion1 as the molecules of gases are4 ,the mass of ,mercury is not exactly known4 ,the only way we have of measuring the masses of the planets is by their influence through gravitation on other bodies near them4 ,when a planet has satellites1 the movements of the satellites tell the story1 and by mathematical calculation the amount of material in the planet can be determined4 ,but ,mercury has no satellite1 and the only way to determine his mass is by observation of his influence on ,venus1 and on an occasional comet which passes near enough to be disturbed by the planet4 ,the particular comet which has been useful in determining the mass of ,mercury is ,encke's4 ,on passing near the sun it comes sometimes near ,mercury1 and the pull it has repeatedly received from that little planet on such occasions is thought to be largely responsible for the comet's having become a part of the solar system4 ,the changes in its orbit caused by these encounters show the power of ,mercury1 and hence the mass4 ,in these ways the mass of ,mercury has been found1 with reasonable belief in its accuracy1 to be about three one-hundredths that of the earth4 ,yet there are1 indeed1 considerable differences regarding it among astronomers4 ,the exact figures are not important to any but the close student4 ,it is certain that the mass of ,mercury is very small--so small that the planet probably never had much atmosphere1 and almost undoubtedly has none to speak of now4 ,the planet could not hold any molecule moving faster than two and forty-five one-hundredths miles a second1 and few gases move as slowly as this4 ,the proportion of light that ,mercury reflects to that which he receives also points to a probable scarcity of atmosphere4 ,if he had an atmosphere1 it would have clouds4 ,clouds have a very high reflecting power1 giving out about seventy-two per cent4 of the light that falls upon them4 ,mercury reflects only fourteen per cent4 of the light he receives1 which shows at least a lack of clouds1 and something more4 ,it indicates a hard1 dark1 almost metallic surface1 and a very considerable density4 ,density1 however1 is the only quality in the possession of which ,mercury seems to occupy a middle ground among the planets1 being slightly less dense than either ,venus1 or ,mars1 or the earth4 ,the earth is the densest of all the planets1 and it is about one-third more dense than ,mercury4 ,density is simply the closeness with which the particles composing a body are packed together4 ,a piece of gold1 for example1 is denser than a piece of iron of the same size4 ,,what ,,the ,,sun ,,does ,,for ,,mercury ,it is probable that ,mercury has no alternations of light and darkness1 causing day and night such as we know them4 ,that is1 the planet does not rotate on its axis in such a way as to turn first one side and then the other toward the sun as the earth does4 ,in this1 as in some other things1 ,mercury must accept the fate that overtakes many other small bodies which revolve around large ones--that of our moon1 for instance1 and the satellites of some of the other planets4 ,working under the law of gravitation1 which gives such power to the large bodies1 the sun has so retarded the rotation of ,mercury that the planet now makes but one rotation on its axis during one circuit around that central body1 and so keeps always the same face toward the sun4 ,some astronomers do not regard this as having been wholly proved2 but all the later observations of ,mercury strongly indicate that it is the fact1 and it is coming to be more and more regarded as established4 ,but1 even if this is the predicament into which ,mercury has come1 the planet is probably not in so bad a plight as many another body to which the same sort of thing has happened4 ,the extreme eccentricity of his orbit1 which has given him the true mercurial temperament1 resulting in sprightliness1 agility1 and changeableness1 is accountable for some mitigating circumstances4 ,the sun may hold him so that he cannot turn his face away from that luminary2 but it cannot keep him from rotating on his axis at a uniform rate of speed1 and from this1 combined with the vagaries caused by his eccentric orbit1 come some interesting things4 ,since ,mercury is less than two-thirds as far from the sun at perihelion as he is at aphelion1 there is a corresponding variation in his rate of speed4 ,when he is nearest the sun1 at perihelion1 he darts along at the rate of thirty-five miles a second2 at aphelion1 when he is farthest from the sun1 he travels only twenty-three miles a second4 ,twenty-three miles in one second is not exactly a snail's pace1 terrestrially considered1 and it is faster than the earth moves at any time2 but the planet was named ,mercury because of his swiftness1 and we would not expect much lagging even when he is moving at his slowest gait4 ,this difference in speed in different parts of his orbit causes what is called the librations of ,mercury4 ,when he is traveling at his swiftest pace he gets a little ahead of his rotation1 the speed of which is uniform1 and thus throws the sunlight somewhat farther around on one side4 ,when his speed decreases1 he falls behind his time of rotation1 and thus gets a little more sunlight on the other side4 ,thus1 during each revolution he juggles the sunlight a little farther around him than he could if he were a more steady-going planet4 ,these librations result in there being two strips on the surface of ,mercury--one on each side--which undoubtedly have a day and night1 varying in length in the different parts of the strips4 ,the part that lies nearest the illuminated side of the planet has alternate periods of sunlight and darkness1 each of considerable duration1 while that part nearest the dark side has merely a glimmer of sunlight every eighty-eight days1 which is ,mercury's sidereal year1 or the time required for him to make one revolution around the sun4 ,these two strips on which the light varies comprise about one-eighth of the surface of ,mercury4 ,one half of his entire surface is always light1 and of the other three-eighths are always dark4 ,it is this dark1 cold side that is turned toward us when ,mercury is nearest to us4 ,it is possible that on those parts of ,mercury where the sunlight and darkness are unstable there may be something resembling a tolerable temperature4 ,they are something more than a thousand miles in breadth1 and perhaps near the center of them the sun may give heat sufficient to enliven and yet not burn4 ,more than likely1 they are alternately scorched and frozen4 ,for it takes more than the mere presence of sunlight to make a climate tolerable4 ,atmosphere is what is necessary1 and we have seen that ,mercury has probably lost practically all his atmosphere long1 long ago4 ,an atmosphere absorbs much of the radiant energy that comes from the sun before it reaches the more solid parts of a planet1 and it also acts as a blanket in preventing the too rapid escape of such heat as the planet may have acquired4 ,thus it has the doubly beneficent office of tempering the rays that would otherwise be scorching and of hindering a radiation that would leave the planet stiffened and frozen4 ,stiffened and frozen is what the dark side of ,mercury undoubtedly is4 ,the sun has never shone upon it since ,mercury became a solid body4 ,all the inherent heat it had has long since passed off into space1 and its temperature must be somewhere near the absolute zero4 ,the absolute zero is the point in temperature where all known substances become solid4 ,it is more than #dej below the ,fahrenheit zero1 or more than #cej lower than any temperature recorded in our arctic regions--a degree of cold unthinkable to any but the scientist4 ,on the other side of ,mercury the heat is beyond anything we have any notion of4 ,with an equal atmosphere it would receive from the sun six thousand times as much light and heat as ,neptune on an equal space1 and1 on an average1 seven times as much as the earth4 ,at ,mercury's distance from the sun his hot side would be more than #cjj above zero1 if there were absolutely no atmospheric protection4 ,even though tempered by a thin atmosphere1 as it may be1 the heat on this side is still probably enough to boil away any water that might be there and to change some other substances from what we regard as their normal state4 ,stability1 at least1 is a quality of the hot and the cold side of ,mercury4 ,scorched and seared and desolate of life1 as we know it1 the one side lies under a blazing1 dazzling sun4 ,cold and hard and bleak1 and no less desolate1 the other side turns its face toward the darkness of space4 ,thus they will remain until the end of time4 ,and let us hope that1 when the final catastrophe occurs and a new nebula is formed1 the matter composing ,mercury may find a place in a larger mass1 and in its new incarnation have a fuller and larger life4 ,it is the atmosphere also which causes twilight1 as well as the gradual changing from heat to cold4 ,with no atmosphere1 we would drop from full daylight to the darkness of starlight at the setting of the sun4 ,so1 with the thin air that ,mercury probably has 7if he has any71 the two zones which are alternately light and dark1 and hot and cold1 are not much better off than the parts which are permanently either light or dark4 ,they are plunged alternately from the temperature and light of the hot side of ,mercury to the temperature of the cold side1 with few gradations to prepare them for such extremes4 ,thus the only part of the planet that might be expected to have any variations of seasons fulfils the expectation with little satisfaction4 ,the only changes in climate which may have an appreciable effect are mainly those caused by the eccentricity of ,mercury's orbit1 which carries him so near the sun at certain times and so comparatively far away at others4 ,when he is nearest the sun he receives more than twice as much heat and light as when he is farthest away4 ,at aphelion he receives four times as much heat and light as the earth4 ,at perihelion the amount of heat and light is increased to more than nine times that of the earth4 ,since it takes ,mercury a little more than twelve weeks to make one revolution around the sun1 he passes from nearest distance to farthest1 or the reverse1 every six weeks4 ,and thus1 as viewed from the planet1 the sun expands gradually for six weeks until it has increased its diameter two and one-half times1 and the next six weeks it diminishes in the same proportion4 ,at such times1 of course1 the amount of heat is more or less according to the planet's distance from the sun2 but all the time it is very great4 ,moreover1 it is believed that the axis on which ,mercury rotates stands perpendicular to his orbit4 ,this being the case1 there would be on ,mercury no change of seasons such as the earth has4 ,the earth's axis is inclined a little more than twenty-three degrees to its orbit1 and from this we get the sun's rays in a great variety of directions and different degrees of obliquity1 causing the seasons1 as we know them1 in grateful variation4 ,with the axis perpendicular1 as it probably is in the case of ,mercury1 the sun's rays fall on the face of the planet always with the same degree of directness1 the only relief from their greatest heat being when the planet backs away from the sun every six weeks1 and when in his librations he turns first one sun-burned cheek and then the other toward the coolness of space4 ,thus we must regard the smallest of our family of planets1 ,mercury1 as always the dwarf among us1 with never a fair chance to develop a rich and luscious life according to our ideas of such a life4 ,beaten by the sun's hard rays1 and with no sufficient atmospheric protection2 pulling always at his tether1 but held firmly with his face to the center2 circling at times with mercurial swiftness and thus cheating the sun into sending its rays farther toward the dark1 cold side of him than it otherwise would1 and with all his defects from a human point of view1 we may still regard him as a right merry1 roguish little planet1 after all4 ,he may be prematurely aged1 he may have missed many experiences that the larger planets are having1 he may have a long time to wait for the final change that will reunite us all2 but he is not lying in sluggish inactivity until it comes4 ,in view of the fact that he is the only planet that twinkles1 may it not suggest1 when we see his ruddy face peering through the thick atmospheric mists near our horizon1 that the impish little body is winking at us1 and that it may be with planets as it is with people3 they may not always be in an unfortunate plight because their fate is different from ours8 ,,transits ,occasionally ,mercury passes at inferior conjunction between us and the disc of the sun1 appearing like a black spot against the sun1 and thus makes what we call a transit4 ,because the planet is so small1 his transit across the sun cannot be seen with the naked eye2 but it is an interesting phenomenon to those who can view it with a telescope1 though1 apparently1 astronomers do not regard it as having any great scientific importance4 ,it is during a transit1 however1 that we watch for confirmation of the theories concerning ,mercury's atmosphere1 which1 if it were a reality1 would show a diffused light about the planet2 and until this question is settled beyond any dispute it will always come up at the time of a transit of ,mercury4 ,at nearly every transit some observer sees these indications of an atmosphere2 but the better the telescope1 the less they seem to be seen4 ,hence it is probable that there is an illusion somewhere either of eye1 or instrument1 or mind1 and that the majority opinion1 which accords to ,mercury practically no atmosphere1 is about the correct one4 ,these transits occur at intervals of seven1 thirteen1 or forty-six years1 according to the position of the earth4 ,they would occur every time that ,mercury passed inferior conjunction if the earth's orbit and that of ,mercury were in exactly the same plane4 ,but the orbit of ,mercury1 we have seen1 is tilted out of the plane of the ecliptic1 which marks our orbit1 seven degrees1 so that the only time the earth and the planet are anywhere nearly in the same plane is when they are at or near the points where their orbits cross each other4 ,the earth is near the two points where ,mercury crosses the ecliptic about ,may #hth and ,november #ith1 so that transits can occur only near these dates4 ,mercury passes these points four times every year1 or once in each revolution around the sun4 ,but the earth is not always there at the same time1 and it is because of this that transits occur only in periods of seven1 thirteen1 or forty-six years4 ,they occur more frequently in ,november than in ,may4 ,the last transit was in ,november1 #aijg4 ,the next will be on ,november #g1 #aiad1 and there will not be another in ,november until #aibg1 an interval of thirteen years4 ,but at the point where the ,may transits occur there will be one on ,may #g1 #aibd4 ,,xi ,,venus ,of all the planets lovely ,venus is the one that is best known and most admired4 ,it far exceeds all the other planets in brilliancy and beauty when as an evening star it hangs in gracious silvery softness above the sun1 which has just passed below the horizon2 and it is not less surpassing in loveliness when as a morning star it comes into view shortly before the sun rises1 its glowing face still silvery and bright1 but yet tinged with the rosy flush of the eastern morning sky4 ,in either position it never twinkles as ,mercury sometimes does1 but shines so steadily and softly that at times its disc can almost be seen with the naked eye1 and it has such brilliancy that its light can often be seen in the daytime1 if one knows when and how to look for the planet4 ,at its brightest it frequently throws a light sufficiently strong to cast a shadow1 as one may easily prove by holding a book or some other opaque object between ,venus and a white background1 such as the wall of a white house4 ,it is six times as bright as the brightest of all the fixed stars1 ,sirius1 the beautiful dog-star1 which we see in winter chasing across the southern skies after ,orion4 ,venus's superior brilliancy is due in part to the fact that it comes nearer to the earth than any other planet2 but it is also intrinsically brighter than any of the others4 ,from equal areas it reflects almost four times as much light as ,mercury and three times as much as ,mars4 ,,when ,,and ,,where ,,to ,,see ,,venus ,when ,venus appears in the sky she is not often mistaken for any other planet4 ,among all the planets she is the most readily recognized and the easiest to find4 ,this is due largely to her extreme brilliancy and a peculiar silvery appearance that none of the other planets have2 but also1 in part1 to her limited range in the sky1 and her favorable situation for observation4 ,unlike ,mercury1 she is far enough away from the sun to be seen above the horizon for as much as three hours after sunset1 and is then sufficiently high in the heavens to be seen free from the vapors of the atmosphere at the horizon4 ,yet1 being one of the inferior planets1 with her orbit smaller and nearer the sun than that of the earth1 she can never get so far from the sun as to be at any uncomfortable height for viewing1 and hence1 when she can be seen at all1 is always an obvious bit of brilliancy and a joy to the beholder4 ,she is never higher in the sky than forty-five degrees1 which is half-way between the horizon and the zenith1 and is never farther away from the sun than forty-eight degrees4 ,one frequently sees a bright planet higher up in the heavens than this2 but it is never ,venus nor ,mercury4 ,we first begin to notice ,venus in the evening sky about six weeks after she has passed superior conjunction4 ,she is then very near the sun1 and sets a little less than half an hour after sundown4 ,evening by evening she grows gradually brighter1 mounts higher and higher in the sky and1 consequently1 sets correspondingly later1 until in a little more than seven months after superior conjunction1 and about six months after we have begun to watch her1 she reaches her greatest elongation east from the sun4 ,at that time she is usually somewhere near forty-five degrees above the sun1 and is a very lovely and conspicuous object in the evening sky1 setting a little more than three hours after sundown4 ,from this point she begins to travel back toward the sun1 still becoming brighter each evening1 because she is really coming nearer to us2 and in about four or five weeks she attains the greatest brilliancy that she will have as an evening star during the particular revolution she is making4 ,about twelve days after her brightest she will reach the point where she seems to be stationary for a time4 ,this is when she is about to overtake us in our journey around the sun4 ,after a short pause she will move on gradually1 her course among the stars then being retrograde or westward2 but what we most notice is that she is drawing nearer to the sun1 setting earlier each evening1 and becoming more and more difficult to see4 ,at the end of about three weeks she is in inferior conjunction1 on a line between us and the sun1 and invisible4 ,she has run her course as an evening star for nine and a half months1 and has been visible anywhere from seven to eight months1 the time of her invisibility depending upon the eye of the observer and the conditions of situation and atmosphere4 ,a week or two later we shall find her a splendid morning star1 rising nearly an hour earlier than the sun4 ,about three weeks thereafter she will be at her brightest as a morning star1 and will continue to be very brilliant for some weeks4 ,in about five more weeks she will have reached her greatest elongation west of the sun1 and will rise about three hours and a half before dawn4 ,then she will begin to retrace her path1 moving eastward1 growing smaller all the time as she goes farther away from us1 and showing a slower apparent movement1 which gives one an agreeable sense of a reluctant parting1 until after a little more than seven months she will have reached the sun and will again be in superior conjunction4 ,she has then been a morning star for nine and a half months1 and has been visible for about the same length of time that she was when she shone as an evening star4 ,this is a brief outline of a typical journey of ,venus through one synodic revolution4 ,she began one of these journeys on ,july #e1 #aiab1 being then in superior conjunction4 ,during the autumn of this year and the winter of #aiab-ac she may be seen shining with great brilliancy in the west at sunset1 and a few hours thereafter4 ,early in ,november1 #aiab1 she and ,jupiter will both be in ,scorpio1 where they will approach within two degrees of each other2 and there is no doubt that their presence will add much charm to that region of the sky during the entire autumn4 ,about the middle of ,february1 #aiac1 ,venus will appear half-way up to the zenith at sunset4 ,she will then be at her greatest distance east of the sun1 and will be very bright2 but1 though a little nearer the sun1 she will be still brighter shortly after the middle of ,march4 ,a month later she will be invisible1 and inferior conjunction will occur on ,april #bdth4 ,during most of ,may and all of ,june and ,july she will be a morning star1 and her brilliant beauty will well repay an early morning outlook4 ,she will get back to superior conjunction on ,february #aa1 #aiad1 and in that year she will be in an ideal situation for us to cultivate a more intimate acquaintance with her4 ,from the latter part of ,march to ,november1 #aiad1 she will be the brightest star in the western evening sky1 and will do much to enhance the beauty of the pleasant summer evenings of that year4 ,the sturdy1 red-faced ,mars will meet her on ,august #eth1 a little more than a month before greatest eastern elongation1 and might almost kiss her pale cheek as they pass within one-sixth of a degree of each other1 a distance equal to less than one-third of the diameter of the moon4 ,the next long period when ,venus will shine as an evening star will comprise the spring and early summer of #aiaf4 ,she will be at her greatest distance from the sun during the last week of ,april1 and will not pass from view until about the first of ,july4 ,then again she will be an evening star1 and so seen in the west during the autumn of #aiag and the winter of #aiag-ah1 reaching greatest eastern elongation during the first few days of ,december1 #aiag4 ,her next return to the evening sky will be for the first eight months of #aiai1 and the next will be for the winter of #aibj-ba and the spring of #aiba4 ,the synodic period of ,venus is nearly five hundred and eighty-four days1 or a little more than one year and seven months4 ,that is1 the planet returns to the same position with relation to the sun and the earth at intervals of about that length4 ,the intervals do vary1 however1 as much as a week or more1 owing to the various motions and situations of the planet and the earth4 ,but every eight years ,venus and the earth come around to almost exactly the same relative position with each other and the sun and the stars1 and thus the appearances of ,venus at the various seasons practically repeat themselves every eight years4 ,the full splendor that she is to offer us in the summer of #aiad will be repeated in #aibb1 just as that of #aiad will but repeat that which she showed in #aijf4 ,and in each of the intervening years she will have again the same appearances that she had eight years before4 ,with the following table as a guide1 the appearances of ,venus can be followed through a number of years with sufficient accuracy for any but a close student of her movements4 ,the exact dates of elongations and conjunctions will vary a few days1 but for at least two or three multiples of eight years not enough to make any material difference in her various aspects4 #aiac--aiba--aibi--aicg ,greatest eastern elongation1 ,february #abth4 ,inferior conjunction1 ,april #bdth4 ,greatest western elongation1 ,july #c;d4 #aiad--aibb--aicj--aich ,superior conjunction1 ,february #aath4 ,greatest eastern elongation1 ,september #agth4 ,inferior conjunction1 ,november #bgth4 #aiae--aibc--aica ,greatest western elongation1 ,february #hth4 ,superior conjunction1 ,september #adth4 #aiaf--aibd--aicb ,greatest eastern elongation1 ,april #bfth4 ,inferior conjunction1 ,july #eth4 ,greatest western elongation1 ,september #adth4 #aiag--aibe--aicc ,superior conjunction1 ,april #bhth4 ,greatest eastern elongation1 ,december #b;d4 #aiah--aibf--aicd ,inferior conjunction1 ,february #aath4 ,greatest eastern elongation1 ,april #bb;d4 ,superior conjunction1 ,november #beth4 #aiai--aibg--aice ,greatest eastern elongation1 ,july #fth4 ,inferior conjunction1 ,september #adth4 ,greatest western elongation1 ,november #beth4 #aibj--aibh ,superior conjunction1 ,july #eth4 ,the meetings of ,venus with the other planets do not1 however1 occur with this delightful regularity4 ,they all are moving about in their own ways1 and engaged in their own affairs1 and only the earth gets back to repeat the meeting with her in just eight years4 ,these eight-year cycles are due to the fact that ,venus makes thirteen revolutions around the sun while the earth makes eight4 ,her journey around the sun requires a little less than two hundred and twenty-five days 7#bbd4gj71 and the earth completes its revolution in a little more than three hundred and sixty-five days 7#cfe4be74 ,so at the end of about two thousand nine hundred and twenty-two days--which equals eight years--they come into almost exactly the same relative positions in their orbits with which they started out1 and begin the cycle anew4 ,,distance ,,and ,,brilliancy ,the mean distance of ,venus from the sun is #fg1bfi1jjj miles4 ,her orbit more nearly approaches the form of a circle than that of any other planet4 ,it is1 like the orbits of the other planets1 an ellipse1 but of such small eccentricity that the difference between her greatest and least distance from the sun is scarcely more than a million miles4 ,light1 traveling as it does1 at the rate of a little more than one hundred and eighty-six thousand miles a second1 goes from the sun to ,venus in about six minutes4 ,it takes something more than eight minutes for light-rays to come from the sun to us4 ,when ,venus is nearest the earth1 her silvery beams come swiftly across to us in a little more than two minutes4 ,when she is farthest from us1 the rays of light require a few seconds more than fourteen minutes to travel over the distance4 ,she is1 when at her greatest distance1 more than one hundred and thirty-five million miles farther from us than when at her nearest4 ,this difference is due not to any great eccentricity in her orbit1 or in that of the earth1 such as causes ,mercury's great variations of distance1 but to the situation of the two bodies in their orbits3 they are nearest together when they are on the same side of the sun1 and farthest apart when on opposite sides4 ,usually at inferior conjunction ,venus is a little more than twenty-five million miles from the earth4 ,at her nearest possible approach to us1 however1 which takes place at inferior conjunction1 when the earth is nearest the sun and ,venus is farthest from it1 a situation which occurs only once or twice in a century1 the distance between us and the planet is only a little more than twenty-three million miles4 ,this is nearer than any other heavenly body ever approaches us1 except the moon and1 so far as we now know1 one small asteroid4 ,also1 it is nearer than ,venus comes to any other heavenly body except perhaps ,mercury4 ,her nearest approach to that planet is also about twenty-three million miles4 ,unfortunately1 our comparative proximity to this beautiful planet does not much aid us in learning anything about her personal peculiarities4 ,shining only by reflected light1 and being1 like ,mercury1 situated nearer to the sun than the earth is1 when she comes around to the same side of the sun on which we are1 her unillumined side is turned toward us1 and at the point of very closest approach she is absolutely invisible to the naked eye4 ,through a telescope1 however1 she can be seen up to the very point of inferior conjunction4 ,what we see then is a mere curved line of light1 so thin is the crescent she presents2 but it is always apparent except when the planet makes a transit4 ,during a transit she is actually in our line of sight with the bright disc of the sun1 and is neither above nor below it1 as at the ordinary times of inferior conjunction4 ,the slender crescent that we ordinarily see offers a very narrow field for observation4 ,if there is any one on ,venus who is studying the earth1 he has a much easier task than we have in our effort to learn something about her4 ,the earth is not only somewhat larger than the planet1 but when the two bodies are nearest together the disc of the earth is fully illuminated1 and so must show a splendid face2 and then1 our atmosphere probably interferes less with close observation than that of ,venus4 ,this little terrestrial system would undoubtedly shine as a magnificent pair of stars if observed from ,venus4 ,at that distance our moon would appear considerably larger than ,venus appears to us when at superior conjunction1 the earth would seem much larger than ,venus ever does to us1 and the distance between them would seem to be a little more than the apparent diameter of the full moon as we see it4 ,the light of the earth must cause much more of a shadow than we ever get from the light of ,venus4 ,it has been suggested that light from the earth is responsible for a dusky illumination of the dark side of ,venus1 which is occasionally seen1 and which enables us to distinguish her entire outline even when only the merest line of a crescent is really illuminated4 ,it is known to be earth-shine that causes what is apparently the same phenomenon often seen by us on the moon2 but it seems that there is no reason to think that our earth1 at its distance1 would be sufficiently brilliant to illuminate ,venus even so slightly4 ,the cause of the illumination is not known2 but it is thought that it may have some electrical origin1 probably similar to that of our aurora4 ,venus has the same phases that ,mercury has4 ,she shows her full face when at superior conjunction1 and is then farthest away and smallest to our view4 ,as she moves toward us she first becomes gibbous1 and then1 at eastern elongation1 like a half-moon4 ,as she comes nearer to inferior conjunction1 and hence nearer to us1 she becomes a thinner and thinner crescent1 and as she goes from inferior to superior conjunction these phases are repeated in reverse order4 ,we see less than half of her face when she is at her greatest brilliancy1 a phase which usually occurs when she is about forty degrees from the sun1 as she is a few weeks before and after inferior conjunction4 ,a very small glass will show the phases of ,venus4 ,they have occasionally been seen without artificial aid to vision by an exceptionally good eye4 ,they were not known1 however1 until they were discovered by ,galileo after the invention of the telescope in #afaj4 ,venus would be many times brighter than she ever appears if the entire disc of the planet could be seen when it is nearest to us4 ,the apparent diameter of the disc at that time is nearly seven times larger than when we see it at the planet's greatest distance from us4 ,when ,venus is in superior conjunction and farthest from the earth the disc measures only ten seconds1 while at inferior conjunction its measure is nearly sixty-seven seconds4 ,the diameter of the moon is about #a1hfh seconds1 so one could string across the diameter of the moon one hundred and eighty-six such planets as ,venus appears to be when at her smallest1 and only twenty-seven of the size that she appears to be when at her largest4 ,between these two extremes of size she changes gradually1 day by day1 from large to small and small to large1 in ceaseless succession1 as she approaches the earth and recedes from it in her orbital journey4 ,apparent diameter is determined by an actual measurement of the disc of a planet1 and in the case of ,venus indicates nothing as to brightness4 ,when the apparent diameter is largest she is not visible to the naked eye4 ,illustration3 ,,the ,,lovely ,,crescent ,,that ,,venus ,,shows ,,when ,,to ,,our ,,view ,,she ,,is ,,at ,,her ,,greatest ,,brilliancy ,this remarkable photograph was made at the ,yerkes ,observatory by ,e4 ,e4 ,barnard4 ,illustration3 ,,relative ,,apparent ,,size ,,of ,,venus ,,at ,,different ,,phases ,,of ,,illumination ,she shows the full disc when farthest away4 ,as she draws nearer she shows first the half moon and then the smaller crescent4 ,she is nearest when she shows the larger crescent4 ,she is brightest1 though1 when she shows the smaller crescent4 ,,venus',s ,,likeness ,,to ,,the ,,earth ,the fact that of all the planets ,venus most resembles this good little earth on which our present lot is cast gives us a strong feeling of kinship with her1 and a more lively interest in all her affairs than we might otherwise have4 ,she and the earth are so nearly of one size that they are often referred to as twin sisters4 ,there is a difference of less than three hundred miles in their diameters1 the earth's diameter measuring #g1iag miles1 and that of ,venus #g1fbi miles4 ,the surface of the planet is about ninety-three per cent4 as extensive as that of the earth2 its mass is a little more than eighty per cent41 and its volume about ninety per cent4 as great as the earth's4 ,differing so little in these particulars1 it follows that it must differ very little in density and gravity4 ,the earth is the densest of all the planets1 and ,venus is only one-tenth less dense than the earth4 ,its force of gravity is not quite nine-tenths that of the earth4 ,a removal from the earth to ,venus would make just a comfortable reduction in one's weight4 ,a person weighing one hundred and seventy-five pounds here would weigh on ,venus one hundred and fifty-four4 ,if through strength of appetite and weakness of will one should take on two hundred pounds of too1 too solid flesh here1 transportation to ,venus would bring about an instantaneous reduction to a solid one hundred and seventy-six pounds--as much of a reduction as would be compatible with health4 ,venus must have begun her career in much the same way that the earth began its career4 ,the nebula that formed her nucleus was probably nearly the same size 7contained about the same amount of matter7 as that with which the earth began its existence4 ,the two bodies have succeeded in capturing about the same amount of loose material1 and their gravity is such that they can hold within their bounds particles traveling at about the same rate of speed4 ,no molecule of gas coming within the range of ,venus's attraction and traveling more slowly than six and thirty-seven hundredths miles per second can escape from ,venus1 and the earth can hold only such as move1 when coming within its own attraction1 with a less speed than six and ninety-five one-hundredths miles per second4 ,the earth has a moon1 and ,venus has none2 but that may be because1 like ,mercury1 ,venus is too near the sun to be permitted to retain such a luxury4 ,it is likely that if1 in her earlier history1 she had within the limit of her gravitative attraction the nucleus of a satellite1 it would have been taken away from her by the stronger attraction of the sun4 ,the same thing would have happened to us if we had been a little nearer the sun4 ,and yet in #afde a moon belonging to ,venus was supposed to have been discovered1 and it was thought to have been seen three times within the rest of that century1 and four times within the first half of the following century4 ,the last supposed view of it was in #agia2 it has never been seen since4 ,there is little doubt that it was an illusion of some kind4 ,perhaps1 though1 ,venus has not the same need of a moon that we have4 ,,atmosphere1 ,,day ,,and ,,night1 ,,and ,,seasons ,there is no doubt that ,venus is in much better plight than ,mercury1 the other inferior planet1 in regard to atmosphere4 ,until recently no one has questioned the belief that her atmosphere is very extensive--twice as heavy1 perhaps1 as that of the earth1 dense1 and full of clouds4 ,the luminous ring about her1 shown when she is making a transit across the face of the sun1 points to a heavy atmosphere2 and no less certain indications of it are given in the faint light which stretches beyond the termination of the horns when she is in the crescent phase1 near inferior conjunction4 ,her very high reflecting power is also indicative of an atmosphere laden with clouds4 ,white clouds form one of the most highly reflecting surfaces known1 and the peculiar brilliancy of ,venus is thought to be in great part due to the presence of large masses of clouds in her atmosphere4 ,by the spectroscope1 and in other ways1 the water necessary to form clouds is shown to be abundant in her atmosphere4 ,even those astronomers who doubt the long-current belief in the large extent of her atmosphere concede an atmosphere of more or less density1 though by one authority it is characterized as somewhat gauzy4 ,there is one vital point concerning the development of ,venus upon which we have as yet no positive knowledge3 the length of time in which she rotates on her axis4 ,this is unfortunate1 because until her time of rotation is known we cannot know much about her physical condition4 ,her rotation1 we know1 determines the length of her day and night1 or whether1 indeed1 she has any4 ,the time of it has been calculated to be anywhere from a little less than one of our days to two hundred and twenty-five1 the latter being also the time of her revolution about the sun4 ,astronomers of equal reputation have come to exactly opposite results in their investigations4 ,to one1 the spectroscope has indicated the short day and night2 to another it has shown no day and night1 but a planet with one face forever toward the sun1 like ,mercury4 ,what appeared to be stable surface markings have been observed1 but have indicated under the eyes of different observers both the short day and no day at all4 ,the disc has been measured during a transit1 and shows so little flattening as to indicate a slow rotation and the long day4 ,on the other hand1 the best authorities think it unlikely that at the distance of ,venus the sun could so retard the planet's rotation as to make it coincide with its time of revolution4 ,thus the question is still an open one4 ,the truth may be that1 owing to the density of her atmosphere1 the surface of ,venus has never been seen at all1 and that the apparently stable markings are but clouds more or less lacking in stability4 ,the difficulty of observing ,venus will probably make it impossible to determine this point by visual observation4 ,it may some day be settled beyond a doubt by the spectroscope4 ,in some way it will surely be settled4 ,astronomers have too often made possible what seemed to be impossible for us to doubt that some one will find a way to discover this secret of ,venus4 ,with them a failure to prove a conclusion does not mean to abandon the subject1 but to try some other means of getting at the truth4 99 99 99 99 99 ,the sun viewed from ,venus would appear considerably larger than it does to us4 ,its apparent diameter to us is a little more than thirty-two minutes1 while on ,venus it would be something more than thirty-eight minutes2 that is1 it would appear about one-fifth larger on ,venus than it does to us4 ,this is enough to make a material difference between the two planets in the amount of heat and light they receive4 ,venus receives nearly twice 7#a4i7 as much heat and light from the sun as we receive1 but less than one-third as much as ,mercury4 ,if she had no atmospheric protection1 there is no question but that she would have a climate disastrously warm for a race of beings constituted as we are4 ,the normal temperature of an unprotected body at the distance of ,venus is about #aeh ,fahrenheit 7#gj ,centigrade74 ,if ,venus is finally proved to have no alternations of day and night1 she is still better off than ,mercury1 who has practically no atmosphere to protect him from the intense heat of the sun4 ,how much protection she has depends altogether on the extent of her atmosphere4 ,it is probably not enough to make the hot side comfortable from our point of view2 and ,venus1 being undoubtedly a solid body with no internal heat1 the cold side must be cold beyond anything we have any conception of4 ,but there may be a very considerable part on each side that1 owing to the refraction of light by the atmosphere1 is more or less well lighted1 and is also more or less protected by this same beneficent atmosphere from deadly extremes of heat and cold4 ,in this situation there would undoubtedly be lively currents of air from the heated side to the cooler2 but even these may in some way carry with them some tempering effects on the climate1 as we know such currents do here on the earth4 ,if it should prove that the length of the day and night on ,venus is something near that of the earth's 7and this seems not unlikely71 she would then be indeed more like a twin sister to us4 ,being next to each other in our distances from the sun1 and of nearly the same size1 differing but little in density1 mass1 volume1 and force of gravity1 with her greater normal heat probably reduced by her heavier atmosphere to a temperature producing climatic conditions not very unlike ours1 and with not very different alternations of day and night1 we might well be considered more nearly related than any of the other members of the solar family4 ,the seasons1 however1 on ,venus and the earth would not have much resemblance to each other4 ,the axis of the earth is inclined to the ecliptic nearly twenty-three and one-half degrees1 so that we receive the sun's rays with varying degrees of obliquity during our yearly journeying around it1 which is the cause of our agreeable change of seasons4 ,venus travels with her axis so slightly inclined to her orbit 7a little more than three degrees7 that each particular parallel of latitude receives practically the same amount of sunlight every day in the year1 though at different parallels the sun's rays strike with varying degrees of obliquity4 ,however delightful or disagreeable the climate may be1 there are no changes of seasons to speak of1 and one could find variety only by going from place to place on the planet4 ,she receives no compensation for this monotony by alternately receding from and approaching the sun as ,mercury does1 or by librations1 such as he has4 ,her orbit being1 as we have seen1 so nearly circular as to permit of only small variations in her distance from the sun1 and her axis so nearly perpendicular to her orbit1 it follows that she has nothing to mark the year2 and1 whether she turns on her axis many times or only once during a revolution1 life on ,venus would be very monotonous to any one accustomed to our delightful variety of climate and seasons4 ,still1 there is nothing in this monotony to prevent ,venus from being a fairly comfortable habitation in some parts for such beings as inhabit the earth4 ,the only real obstacle to habitability on ,venus would be her lack of rotation and all that it involves4 ,since we are not sure that we can see the surface of ,venus1 we cannot say what that surface is4 ,nevertheless1 there is some reason to suspect that we would find there mountains of vast height4 ,certain irregularities have been observed at times1 of a kind to indicate mountains covered with snow1 extending beyond the clouds4 ,they have been estimated to be many miles higher than any mountains we have on earth1 their height depending somewhat upon the temperament of the observer4 ,but inasmuch as these same high mountains have sometimes been thought to be only masses of clouds1 it seems hardly safe to pronounce definitely upon them4 ,,transits ,on rare occasions1 when ,venus is in inferior conjunction1 she makes a transit1 and can then be seen as a black dot moving over the bright face of the sun4 ,transits can occur only when the earth and the planet are near the point where their orbits cross each other4 ,the earth is at this point every year on ,june #gth and ,december #gth2 but the orbit of ,venus is such that she is there on the proper dates only four times in a period of two hundred and forty-three years4 ,in every two hundred and forty-three years four transits take place4 ,they occur in pairs1 eight years apart1 and in the same month4 ,if a pair occur in ,june1 it will be one hundred and five and one-half years after the last one of the pair until we have the first of the ,december pair of transits4 ,after that it will be one hundred and twenty-one and a half years until we have the first of another pair of ,june transits4 ,the first transit of ,venus that was scientifically observed was in ,december1 #afci4 ,it was the last of a ,december pair1 there having been a transit eight years before1 in ,december1 #afca4 ,one hundred and twenty-one and a half years later1 in #agfa1 a ,june transit occurred1 and in #agfi another one took place in ,june4 ,then there were no more for one hundred and five and one-half years1 when we had a ,december pair in #ahgd and #ahhb4 ,the next ones will be in ,june1 #bjjd and #bjab4 ,great importance was attached to those transits that occurred in #ahgd and #ahhb1 because they were expected to be useful in determining with greater exactness the distance of the sun4 ,extensive preparations were made for scientific observation of them2 but the results were not satisfactory1 largely because the atmosphere of ,venus prevented her from showing a sharp outline at the moment of entering upon and of leaving the face of the sun4 ,the main scientific value of a transit of ,venus now is in the opportunity it may offer to investigate the nature of her atmosphere4 ,even though that interesting question may have been practically settled before another transit takes place1 it will be important to know to what degree the phenomena observed at the next transit confirm the decision4 99 99 99 99 99 ,on account of the surpassing brilliancy of ,venus1 the brightest of all the heavenly bodies after the sun and moon1 she was to the ancients the most important of all the stars and planets4 ,she was the supreme evening and morning star4 ,as evening star she was known as ,hesperus1 or ,vesper2 as a morning star she was called ,phosphorus1 or ,lucifer1 and under all these names she is frequently mentioned in ,greek and ,latin and kindred literatures4 ,the symbol of ,venus is 1 a figure which is nothing more than the conventionalized form of a looking-glass1 an article that is often pictured in the hands of the goddess for whom our beautiful planet was named4 ,in her general aspect she is as placidly splendid and charming as ever a goddess could be1 and it is not strange that the happy ears that could hear such strains should find her1 as they did1 singing a rich contralto in the music of the spheres4 ,jupiter and ,saturn1 under this mythological apportionment1 sang bass1 ,mars took care of the tenor strains1 and the high soprano was carried by our little dwarf ,mercury4 ,,xii ,,mars ,the planet that varies most in the beauty of its aspect is ,mars4 ,it is as much as fifty times brighter when it is nearest to us than it is at its greatest distance from us4 ,at its brightest it is many times more brilliant than any of the first-magnitude stars2 but when it leaves our neighborhood and goes far off into space in its journey around the sun1 its glory is so dimmed that it becomes not brighter than an ordinary second-magnitude star1 such as the pole-star1 and less brilliant than the brightest stars in the ,big ,dipper4 ,these extreme changes of brightness are due not so much to any great distance that ,mars goes from us in comparison with other planets as to its coming so very near to us at times4 ,it is1 after all1 a small body1 and no great distance1 as heavenly distances go1 is required to make it show so4 ,but the eccentricity of its orbit brings it sometimes very near us1 and its near approaches are at a time when we can see its entire disc1 and not a mere crescent1 such as we see when ,venus is nearest to us4 ,mars does not come quite so near to us as ,venus comes1 but when he is in the best position to be seen he is much nearer than she is when in her best position4 ,for we have seen that ,venus is brightest before she reaches her nearest position to us1 while ,mars is brightest when he is at his nearest to us4 ,when ,venus is at greatest elongation she is three times farther away than ,mars is at his nearest4 ,,how ,,to ,,identify ,,mars ,but with all his variations in brilliancy and beauty ,mars remains ever a charming1 rosy-hued planet1 shining always with a steady1 clear light1 and when once we have come to know him is not easily mistaken for any other planet1 or for any of the brilliant stars that may more or less resemble him in color4 ,red in varying degrees of intensity is1 perhaps1 the most obviously distinguishing mark of ,mars2 but his own characteristics are never more distinct than when his path takes him into the region of the two best-known red stars in the heavens4 ,these are ,antares1 the glowing star in the constellation ,scorpio1 which we see in the southern sky during the summer1 and ruddy ,aldebaran1 which shines in the head of ,taurus and under the ,pleiades through the bright wintry nights4 ,on every journey around the skies ,mars passes near these two stars4 ,they are both in the constellations of the zodiac1 and are often quite near to ,mars1 as well as to the other planets and the moon4 ,the stars1 though of the same color as ,mars1 are much more jewel-like than the planet4 ,mars is less sparkling4 ,when it is small1 it shows a placid1 rosy little disc1 without much gaiety1 and not in any way suggesting anything martial2 but at its largest1 it has a distinctly flame-like aspect1 which easily suggests why it was named for the god of war4 ,illustration3 ,,the ,,two ,,phases ,,of ,,mars ,we see its full face when it is opposite the sun4 ,when half-way between opposition and conjunction it becomes gibbous1 as shown in the photograph on the right4 ,these photographs were made at the ,mt4 ,wilson ,observatory4 ,mercury is the only planet that in color even suggests ,mars1 and for ,mercury it can never be mistaken after one has once seen the two planets4 ,mercury1 we know1 is always very near the sun2 but when visible at all is1 even in that unfavorable situation1 always as bright as a first-magnitude star4 ,mars is near the sun1 to our view1 only when it is approaching conjunction1 and it is then so far from us that it always appears as a rather small star1 and1 while never insignificant1 is1 in this situation1 quite inconspicuous even as compared with the rarely visible ,mercury4 ,on seeing a planet1 then1 sufficiently high above the horizon to attract one's attention1 one may be sure that it is ,mars if it is red1 and equally sure that it is not ,mars if it does not show this color4 ,under certain atmospheric conditions the sun1 moon1 and all the planets sometimes appear red when they are very near the horizon2 but in this situation there is always something other than color that marks them4 ,if its color is not a sufficient mark by which to identify ,mars1 a still further difference between it and the stars is its markedly rapid movement4 ,a single night will make a sufficient change in its position to show the planet as a wanderer4 ,on an average1 it travels over about four-tenths of a degree in the heavens in one day4 ,this equals more than half the diameter of the moon1 a change of position sufficiently great to be easily detected4 ,,when ,,and ,,where ,,mars ,,may ,,be ,,seen ,unlike ,mercury and ,venus1 which are never far from the sun1 and can be seen only for a comparatively short time either early in the morning or in the evening1 and are never very high up in the skies1 ,mars may be situated so that it can be seen at any time of the night1 and also at any distance from the sun4 ,when it is in opposition it rises just as the sun sets1 and is then in view all night4 ,at this time it is nearer1 larger1 and brighter than at any other time in the particular revolution it is then making1 and1 consequently1 is in the best position to be viewed by us that it will have during that revolution4 ,oppositions differ1 however1 in different revolutions1 and some show us the planet more splendidly brilliant than it appears at others4 ,the oppositions at which ,mars shows most brilliant take place1 fortunately1 in the summer and early autumn--the seasons which are most agreeable for outdoor observation4 ,he is then traveling through that region of the sky1 sparse in stars1 that lies between ,sagittarius and ,aries2 and1 since the ecliptic there runs rather low in the sky1 he can easily be observed at any time in the night without any neck-breaking postures4 ,these favorable oppositions occur in the summer because the earth is in line in the latter part of ,august with that point in the orbit of ,mars where the planet makes its nearest approach to the sun4 ,oppositions never occur when ,mars is exactly at that point2 but they do occur when he is very near it1 and at such times we see him in his greatest glory4 ,this happens once every fifteen or seventeen years4 ,but at any summer or early-autumn opposition ,mars is not very far from this nearest point to the sun1 so that at any oppositions during these seasons he is very brilliant and almost as bright as when he is at his best4 ,the earth is in line in the winter with that part of ,mars's orbit which carries him farthest from the sun1 and at opposition then he is much less bright than at the summer oppositions4 ,he is at the same time in those constellations which pass nearly overhead in the sky1 and cannot be quite so comfortably seen at all times in the night as he can be in the summer4 ,the very best and most brilliant oppositions occur in the latter part of ,august or in the early part of ,september2 the least favorable ones occur in ,february4 ,the others vary in brilliancy according to their distance from these favorable and unfavorable dates1 all the summer ones being quite brilliant1 and all the winter ones much less so4 ,at any opposition1 though1 however unfavorable1 the planet is much nearer to us and much brighter than when in conjunction4 ,it is worth one's while1 even at some inconvenience1 to see ,mars at whatever time he is in opposition1 for he is a delight to the observer1 and always notable in the part of the skies through which he is then passing4 ,there are some aspects of the planet that are so charming at a winter opposition that it is a positive loss not to have seen him at such times4 ,he is more isolated and conspicuous in the summer2 but he fits well in that gay company of winter stars that shine more brilliantly than any others1 and we can easily feel something akin to family pride as we watch him moving so graciously among them4 ,mars makes a complete circuit of the skies1 and comes back into the same position with relation to the sun and the earth on an average every seven hundred and eighty days1 which makes his synodic period longer than that of any other planet4 ,owing to the great eccentricity of his orbit1 and his consequent unequal motion in the various parts of it1 the synodic period varies as much as thirty-five or thirty-six days4 ,one cannot say1 therefore1 without computation of some length1 just exactly how many days will elapse between any two single oppositions4 ,for mere purposes of naked-eye observation the variations in the synodic period of ,mars do not make any difference1 for the planet is in view practically all night for many nights before and after opposition1 with changes of brightness too small to be noticed by an untrained eye4 ,for at least two months at the time of opposition it has almost the same aspect to us4 ,at that time it is always in the east early in the evening1 and shines all night4 ,for nearly nine months afterward it is visible and conspicuous in the evening sky1 appearing each evening nearer and nearer to the western horizon1 until finally1 in a little more than a year after opposition1 it passes behind the sun and becomes a morning star4 ,but1 as it then rises before the sun and passes across the heavens in the daytime1 it is invisible to us4 ,it is pleasant1 however1 at such times to know that as the sun passes across the skies in its daily journey ,mars is up there1 within a certain distance from it1 making the same journey with it1 beaming down upon us with the same lively light that it shows at night1 and could be as well seen at any time but for the too dazzling rays of the sun4 ,mars will be in conjunction in ,november of this year 7#aiab71 and will not be visible in the evening during #aiac until toward the end of the year4 ,the next opposition after the publication of this book will occur in ,january1 #aiad4 ,from that time until the following autumn the planet may be seen in the evening4 ,in #aiae ,mars will not be visible in the evening sky until late in the year4 ,after ,november it will be in the east in the evening1 rising earlier each evening1 until at opposition1 early in #aiaf1 it will rise at sunset and will be visible in the evening during the entire summer and autumn of that year1 but will not be extraordinarily bright4 ,in #aiag it will be again invisible in the evening4 ,in #aiah it will be in opposition in the early spring1 and will shine in the evening all the rest of that year4 ,it will not be visible in the evening in #aiai1 but will be in opposition again in the latter part of ,april1 #aibj1 and will shine in the evening all of that year and the early part of the next1 when it will again disappear from evening view and will not emerge again until it is nearing a fine opposition that will take place just at the beginning of the summer of #aibb4 ,the planet will then be in the constellation ,scorpio1 not far from ,antares1 and this will afford an excellent opportunity to see these two ruddy bodies near together4 ,in #aibd there will be an exceptionally brilliant opposition1 which will occur during the last week of ,august1 and the planet will then be about as brilliant as it ever appears1 and will be very favorably situated for observation in the constellation ,pisces4 ,we shall then see ,mars in the flame-like phase of his beauty1 and he will dominate the evening sky during the whole of that summer4 ,at oppositions such as this one ,mars is more favorably situated for observation from the earth than any other heavenly body except the moon4 ,the next oppositions will take place the last week in ,october1 #aibf1 in ,december1 #aibh1 ,january1 #aica1 early ,march1 #aice1 the middle of ,may1 #aicg2 and then we will have two more splendidly brilliant oppositions in ,july1 #aici1 and early ,october1 #aida1 respectively4 ,during the years that ,mars does not appear in the evening we need not be deprived of a sight of the planet if we will look for it in the morning sky4 ,a few months after conjunction it may be seen as a morning star1 rising shortly before the sun4 ,it rises earlier each morning1 and hence can be seen each morning for a longer time4 ,after its hour of rising has reached midnight it then passes into the evening sky and rises earlier each evening until it reaches opposition4 ,the movement of ,mars among the stars1 as we see it1 is generally toward the east1 and we can see by looking that it changes its place among the constellations in that direction1 going from ,aries to ,taurus1 from ,taurus to ,gemini1 and so on4 ,on each side of opposition1 however1 the planet appears for a few weeks to be moving westward among the stars4 ,this is the retrograde motion which an outer planet appears to have when we are overtaking and passing it1 and which has been explained in the chapters on the movements of the planets4 ,,size1 ,,atmosphere1 ,,and ,,temperature ,in size ,mars is one of the smallest members of our solar family4 ,its mass is a little more than one-ninth that of the earth1 and its entire surface is only about one-third as great as ours4 ,it is the merest trifle more dense than ,mercury1 but only about sixty-six one-hundredths as dense as the earth4 ,its force of gravity is about thirty-six one-hundredths as powerful as that of the earth4 ,a man weighing two hundred pounds here would be relieved of about one hundred and twenty-four pounds of his weight if transported to ,mars1 weighing there only seventy-six pounds1 which would greatly increase his efficiency if he were in other respects the same4 ,it would necessarily follow that ,mars1 having such small force of gravity1 could not long retain a heavy atmosphere1 even if it had set out with such a one4 ,no molecule of gas moving at a greater speed than three and thirteen-hundredths miles a second could be held by ,mars in its atmosphere1 and so much as it may have had of the rarer gases which move with great rapidity must have escaped long ago4 ,but it did not begin life with an atmosphere heavy in proportion to that which the larger planets have4 ,we have seen1 in the case of ,mercury1 that being one of the small planets entails many restrictions in development4 ,such planets not only lose their atmosphere more quickly than the larger ones1 but it is less dense to begin with4 ,the atmosphere of ,mars is probably no denser than we have at the tops of our highest mountains1 more than likely not even so dense as that4 ,there is some water vapor1 and there are a few clouds most of the time2 but in the main the atmosphere is so clear and thin that we can without any doubt see the actual surface of the planet4 ,it is not certain that the clouds we see are formed from water vapor1 as clouds of the ordinary kind are4 ,it has been suggested that they may be simply dust-clouds4 ,but this is as yet not much more than a suggestion1 and nothing convincing has been offered to substantiate the idea4 ,even dust-clouds would need currents of air to create and carry them2 so1 whether dust or vapor1 the presence of clouds implies an atmosphere4 ,the famous white polar caps1 which furnish so many news items to the journals1 are also of uncertain origin1 and their true nature can be determined only by a fuller knowledge of the atmosphere of ,mars4 ,they appear in the winter season on the planet and disappear in its summer1 so there seems to be no doubt that they are dependent in some way on the temperature in the polar regions of ,mars4 ,if they are hoar-frost or snow1 they are condensations of water vapor2 and1 in that case1 when they disappear there must be sufficient heat to melt them4 ,it has been contended that the sun's rays fall too obliquely on the poles of ,mars to melt more than a few inches of snow1 but that the caps may be light snow or frost1 and thus capable of being dissolved by even such oblique rays of sunlight as they receive4 ,also it has been suggested that the deposit resembling snow may be carbon dioxide1 which condenses into a white substance at a temperature more than a hundred degrees 7-#aji ,fahr47 lower than is necessary to produce snow and melts at a correspondingly low temperature4 ,what the nature of the phenomenon seen at the poles of ,mars is depends largely upon what the temperature is2 and the temperature in turn is dependent in some measure on the density and constitution of the atmosphere1 as well as the planet's distance from the sun4 ,the normal temperature of an unprotected body at the distance of ,mars from the sun is about thirty-two degrees blow zero 7,fahrenheit72 and since we know ,mars has no dense atmosphere to retain the heat it acquires1 it is natural to suppose the existence there of a very low temperature1 and one incompatible with our ideas of life and growth4 ,the most favorable conclusions do not place the mean temperature higher than forty-eight degrees ,fahrenheit4 ,it is certain that the planet must be subjected to great extremes of temperature within its range1 since its filmy robe of atmosphere cannot protect it to any extent from the direct rays of the sun during the day1 nor prevent the heat from escaping with great rapidity at night2 so that1 whatever heat it may gain in the daytime1 it probably loses much of it during the night4 ,until we know more of the constitution of the atmosphere of ,mars we can know nothing certainly about its temperature beyond the fact that it is much colder than ours and more subject to variations4 ,anything much more definite than this is speculative at present4 ,but with all the observation that is now given to ,mars1 and with the always increasing facilities for the work1 many uncertainties regarding the planet are likely to be made clear before long4 ,the spectroscope will probably be the final resort for facts concerning the atmosphere4 ,,distance ,,and ,,brilliancy ,mars is1 on an average1 about one and a half times farther from the sun than we are4 ,its mean distance is1 in round numbers1 one hundred and forty-one million miles2 but1 since its orbit is very eccentric--more eccentric than that of any other of the planets except ,mercury--its distance from the sun varies as much as twenty-six million miles4 ,at its nearest the planet is a little more than one hundred and twenty-eight million miles from the sun4 ,its greatest distance from that luminary is one hundred and fifty-four million miles4 ,at its mean distance something more than twelve and a half minutes are required for light to travel from the sun to the planet4 ,the sun becomes quite a medium-sized object as viewed from ,mars1 and must lose some of the majesty of aspect that it has to us4 ,its apparent diameter is about twenty-one minutes1 which would make it less than two-thirds as large as we see it4 ,the average amount of light and heat that it furnishes to that poor1 lightly clad little planet is less than half as much as we receive1 though when the planet is at perihelion the sun's radiance is forty per cent4 more powerful than when it is at its greatest distance from the source of these life-giving forces4 ,the eccentricity of the orbit of ,mars is the cause also of his great variations in distance from us1 and hence of his extreme changes in brilliancy4 ,these changes are many times greater with reference to the earth than to the sun4 ,at the planet's nearest approach to us it comes a little nearer than thirty-five millions of miles4 ,this is when it is in opposition in ,august4 ,when opposition occurs in ,february1 it is as much as sixty-two millions of miles from us2 and when it is in conjunction1 and on the other side of the sun from us1 it is sometimes two hundred and forty-eight million miles distant4 ,at his nearest approach light leaps over to us from ,mars in about four minutes and eighteen seconds2 at his greatest distance it cannot reach us in less than twenty-two minutes4 ,the apparent mean diameter of ,mars is about nine and fifty-six hundredths seconds1 but varies from three and six-tenths seconds1 when the planet is farthest away1 to twenty-five seconds when it is nearest to us4 ,while ,mars does not exhibit the phases of the inner planets ,venus and ,mercury1 by showing a disc sometimes at half-full and sometimes at crescent it is sufficiently near us to be1 in certain positions1 gibbous1 or to show a little less than a full face4 ,when this occurs ,mars is about half-way between opposition and conjunction1 and the earth and the sun are so situated that we are slightly to one side of the fully illuminated face of ,mars4 ,this phase1 however1 is not sufficiently marked to make any material difference in the brilliancy of the planet4 ,it is not apparent without the aid of a telescope4 ,from ,mars the earth shows all the phases that ,venus shows to us4 ,when ,mars is flaming down upon us in his position of greatest brilliancy we present to him a thin crescent4 ,when he sees our full face we are on the opposite side of the sun from him4 ,it would be necessary to have a more brilliant electrical illumination than any we have yet seen to lighten the dark side of the earth and exchange signals with ,mars when we are nearest to him--if1 indeed1 our atmosphere would permit from ,mars any view at all of the surface of the earth1 which is not at all certain4 ,in spite of its phases1 the earth must shine on ,mars at times in a very attractive way4 ,it is not so bright1 perhaps1 as ,venus is to us1 nor as we are to ,venus2 but with our moon circling about us we may well be1 when in a favorable situation1 a very interesting double star1 the distance between earth and moon appearing on ,mars about equal to one-fourth of the apparent diameter of the moon4 ,illustration3 ,,mars3 ,,difference ,,in ,,its ,,apparent ,,size ,,at ,,its ,,nearest1 ,,middle1 ,,and ,,farthest ,,distance ,,from ,,the ,,earth ,mars appears fifty times brighter when nearest than when farthest away4 ,,day ,,and ,,night1 ,,and ,,seasons ,owing to the undoubted permanent markings on the surface of ,mars1 astronomers have been able to determine the length of its day with much less likelihood of error than in the case of any other planet except the one on which we dwell4 ,it rotates on its axis in twenty-four hours1 thirty-seven minutes1 and twenty-three seconds1 which makes its day nearly forty minutes longer than ours4 ,in our greed for all too fleeting time we may feel a little envy of these extra minutes1 which would mean so much to us if added to our day4 ,but they do not seem so important when we consider that while ,mars is having six hundred and seventy of these days we are having six hundred and eighty-seven of ours1 which1 after all1 seems to give us eighteen days more of time4 ,our attitude toward the situation depends upon the point of view4 ,the axis of ,mars is inclined to its orbit about twenty-four degrees and fifty minutes4 ,this is but little more than the inclination of the earth's axis1 which is twenty-three degrees and twenty-seven minutes4 ,mars1 therefore1 has seasons very much like ours4 ,they are1 however1 slightly more marked than ours1 because of the somewhat greater inclination of the axis of the planet2 and they are nearly double the length of ours1 because it takes ,mars nearly two of our years to make its journey around the sun4 ,its seasons1 then1 are nearly six months long1 while ours are but three4 ,it has frigid1 temperate1 and torrid zones1 practically the same as the earth has4 ,its greatest inequalities of season are caused by the eccentricity of its orbit4 ,it is1 like the earth1 farthest away from the sun when it is summer in the northern hemisphere2 and in this situation it travels so much more slowly than when it is near the sun that summer in its northern hemisphere is seventy-five days longer than the same season in the southern hemisphere4 ,the northern summer and the southern winter are each three hundred and eighty days long1 while the reverse seasons in each hemisphere are only three hundred and six days long4 ,the northern summer is not only longer but also cooler than the southern1 and the northern winter is shorter and warmer than the southern4 ,which hemisphere has the more favorable climate depends upon what is needed on ,mars to maintain life4 ,it may be that in this regard the shorter1 hotter1 southern summer is the best season the planet affords4 ,,surface ,,aspects ,,of ,,mars ,seen through a telescope1 ,mars is not so red as it appears to the naked eye4 ,one of the best observers of it has compared it to an opal1 and it surely has some of the qualities of an opal in the diversity of aspect that it shows to different observers from different points of view4 ,no other planet has been so subjected to controversy over what appears on its surface4 ,this is partly due to its being the only planet whose surface is without doubt open to our view and in a situation where it can be minutely studied1 and partly to the fact that the controversy involves questions concerning life and intelligence1 which are always of intense human interest4 ,matters of this vital sort are never accepted without dispute4 ,that is one way of getting at the truth4 ,in the intensity of the discussion the question of the existence of the phenomena and that of the meaning ascribed to them are sometimes unnecessarily made to depend upon each other4 ,in the case of ,mars it may well be that there is less difference of opinion as to what is really seen on its surface than as to the meaning of the phenomena4 ,there are recorded observations made of ,mars as early as #bgb ,b4,c41 more than two thousand years ago1 and it has been nearly two hundred and fifty years since the snow-caps were first seen4 ,through the telescope not only the snow-caps are plainly visible at the proper seasons1 but there are also visible dark patches over the surface1 showing a variety of color1 and in certain parts changing somewhat as the seasons change4 ,it is one of these patches1 the outline of which suggests a somewhat twisted eye1 that is known as the 8eye of ,mars40 ,the main surface of the planet is reddish yellow in color2 the patches on it are variously described as gray1 grayish green1 or blue1 colors which in combination could easily take on a tone of any of them according to the eye of the observer1 and this portion of the planet's surface does1 in fact1 show first one and then the other of them predominating4 ,when the planet's differences of color were first observed1 the reddish-yellow portion was supposed to be land1 and the areas of varying bluish-green and gray were thought to be the waters of the ever-changing seas4 ,a little after the middle of the last century some keen eyes saw a few streaks or markings of some sort across the land areas1 and in #ahgg a close study of the planet by an eminent ,italian astronomer1 ,schiaparelli1 brought to his view many greenish streaks1 all directed toward the so-called seas1 and sometimes seeming to intersect there4 ,in publishing this discovery ,schiaparelli called these streaks canalli1 which is properly translated 8channels10 but appeared in ,english as 8canals40 ,since 8canal0 with us means artificially constructed waterways1 the discovery became at once one of universal interest2 for artificial waterways mean human beings to construct them1 and it was an intensely interesting thing to know that ,mars was probably inhabited with beings at least somewhat after our own kind4 ,it was a new world4 ,the little planet became a topic of absorbing interest to all of us4 ,and thus began the controversy over the habitability of ,mars1 and the meaning of its surface features1 in which astronomers1 seeking only for the truth1 have taken a much more dignified part than they have sometimes been more or less sensationally represented as doing4 ,the discoverer of the so-called canals himself believed them to be natural waterways cutting through the land after the manner of our straits and channels1 and had very little to say in explanation of them4 ,but his work gave a new impetus to the study of this little brother world of ours4 ,in our own country the observatory at ,flagstaff is the one the best known among those doing research work on ,mars2 but it is not the only one4 ,the observatory there is finely situated in the thin1 clear atmosphere of ,arizona1 the mechanical facilities for such work are good1 and there seems no doubt that there are there some observers who have eyes that were made for seeing4 ,all that the sharp vision of ,schiaparelli saw has been seen there1 and much more4 ,several hundred canals have been discovered1 and at certain seasons many of them have appeared to become double4 ,their courses have been followed1 and their appearances and disappearances have been watched4 ,somewhere near six hundred of them have been mapped4 ,according to these maps1 the canals seem to be laid out with a geometrical precision such as nature is not likely to follow2 they run across some regions that were formerly supposed to be water1 and they have points of convergence every here and there1 forming at such points large dark areas4 ,naturally1 when a person has discovered any new and curious phenomenon in nature he seeks to determine the exact meaning of it4 ,it would have very little interest for him if he did not1 and it would be a dry lot of facts that did not arouse a desire to do this4 ,the interpretation put upon what has been seen at the observatory at ,flagstaff is1 in brief1 about as follows3 ,the surface of ,mars has no oceans or mountains4 ,the reddish areas1 which form the larger part of the surface1 are deserts4 ,the blue-green streaks are ribbons of vegetation along each side of artificially constructed waterways1 which are of immense length and cross and recross each other until they somewhat resemble a network of lines over the desert surface of the planet1 and are used for irrigating this arid region4 ,the points where the canals converge and form the large dark spots are oases made by the water carried by the canals4 ,the water is supplied by the melting of the caps of snow at the poles during the ,martian summer1 the expanding of the lines of vegetation seeming to occur at periods corresponding to the time required for the water of the melting snow to reach the oases4 ,the presence of this vast system of artificial waterways covering a large part of the surface of ,mars makes it seem probable that 8,mars is inhabited by beings of some sort or other10 that these beings are not men such as we know anything about1 but that 8there may be a local intelligence equal to or superior to ours40 ,these conclusions concerning what is seen on ,mars are not held by any one to be completely proved1 but are thought by their author to follow reasonably from the phenomena as observed4 ,by persons of a different temperament they are regarded as too complete an explanation1 particularly as the data upon which they are founded are not undisputed4 ,some of the best astronomers have not been able even to see the multitude of fine lines1 much less to give any explanation of them4 ,others do not regard it as certain that they are so geometric in their outlines as to suggest anything more than cracks or clefts in the surface of ,mars1 such as might be made by nature1 and consider that1 instead of indicating life1 human or other1 they may be the marks of age1 such as similar lines or cracks which have been observed on ,mercury seem to be4 ,also1 it is not at all certain that there is sufficient water vapor in the slight atmosphere of ,mars to furnish the snow necessary for this great irrigating system1 nor the heat to melt it at the proper season4 ,the natural temperature of ,mars would be1 as we have seen1 very low1 and unless it is modified in some way not yet indicated everything points to a frigidity too intense to permit the continuance of life and growth of any sort known to us4 ,these things must all be reckoned with before anything certain can be known of the surface of ,mars4 ,the difficulty of pronouncing upon the minute details is impressively indicated by ,professor ,moulton1 who says that1 even under the finest conditions and with the best telescopes1 it is like viewing 8a perfectly accurate relief map of the whole ,united ,states made on such a scale that it would be only three inches in diameter and held at a distance of three feet from the eye40 ,under such a near limit of vision1 we can well see that differences of opinion might arise4 ,the mere fact that some astronomers have not seen the lines on ,mars does not mean that they deny their existence4 ,some eyes have greater defining power than others1 as well as some telescopes1 as every one knows4 ,but while all the lines and patches of color that are claimed to have been seen on ,mars doubtless have been seen by some persons1 yet it is not necessary to accept the interpretation of them given by lively-minded observers when it is not convincing4 ,there may be vegetation on ,mars1 and even intelligent beings4 ,we do not know2 and thus far there is not much to support1 even by inference1 the view that there are4 ,if we want the truth1 we are brought no nearer to it by giving full credence to a speculative theory simply because it is interesting and pleasant2 and thus far all theories advanced as to the nature of the surface markings on ,mars are speculations1 though there is no doubt that the marks are there4 ,it is pleasing1 however1 to contemplate the idea of there being on ,mars1 or on any other planet1 an active intelligence of any sort resembling what we have here on earth1 and it is not strange that such a wide-spread popular interest should attach to ,mars1 in view of what has been suggested by the markings on its surface4 ,,the ,,satellites ,,of ,,mars ,mars has a little family of two moons4 ,tiny little bodies they are1 the smallest in the solar family except1 perhaps1 an occasional asteroid4 ,neither one of them is more than ten miles in diameter1 and the two together are smaller than any other known satellite4 ,they can only be seen when ,mars is in opposition1 and then only with a fairly large telescope4 ,they were discovered in #ahgg1 and named ,phobos and ,deimos1 the names of the two attendants of the god of war4 ,phobos is the brighter and the nearer to the planet4 ,it is less than four thousand miles from the surface of ,mars2 and on account of its being so near and the shape of ,mars being a spheroid1 like that of the earth1 the little satellite can never be seen from ,mars beyond sixty-nine degrees of latitude on each side of the equator4 ,within these limits it shows great activity4 ,it makes a complete circuit around ,mars in seven and a half hours2 and this swift revolution1 combined with the motion of ,mars on its axis1 makes ,phobos seem to rise in the west and set in the east1 pass over the heavens in less than twelve hours1 and go through all its phases1 from 8new0 to 8full10 one and a half times every night4 ,its light is rather insignificant1 being about sixty times less than we receive from our satellite2 but1 on the whole1 it must be a rather gay and pleasant little moon4 ,deimos is not any larger than ,phobos1 and not as bright2 but it is slightly less difficult for us to see1 because it is between two and three times farther away from ,mars than ,phobos is1 and thus not so much lost in the light of the planet4 ,it circles around ,mars in a little more than thirty hours1 and this1 being only six hours more than ,mars consumes in turning around on its axis1 results in requiring more than two days for the satellite to pass from rising to setting4 ,between rising and setting it goes through its phases four times4 ,it can be seen from all parts of ,mars1 but gives very little light to the planet--more than a thousand times less than our moon gives us4 ,the symbol of ,mars is 1 a conventionalized figure representing a shield and a spear--implements of war appropriate for the use of the deity especially connected with warfare4 ,,xiii ,,jupiter ,one never feels so impressed with the power of the sun as when one contemplates it in relation to ,jupiter4 ,great ,jupiter1 he may well be called1 nearly five hundred million miles out in space1 almost a sun himself1 the center of a system containing bodies larger than the sun's nearest planet1 ,mercury2 and yet just ,jupiter1 one of the planets1 held firmly in leash like the others by the sun's overwhelming force of gravity1 forever compelled to revolve about that parent body with the rest of its offspring1 to stay at home within the bounds of the sun's domain1 to keep within certain limits in his own orbit1 forced to hasten on when he comes nearest the power that controls him1 and unable to keep up the same rate of speed when he is farther away4 ,one may well wonder at the immensity beyond comprehension of the stars1 among which our sun is but a very small one1 when one considers how even this small one can thus swing huge ,jupiter about4 ,for ,jupiter is1 after the sun itself1 the mammoth member of our system4 ,in volume he is larger than all the other planets put together1 and in mass he is more than double as large as the combined mass of all the others4 ,he is about equal to the sun in density1 and about one-fourth as dense as the earth4 ,there is less difference in size between ,jupiter and the sun than there is between ,jupiter and the earth4 ,his diameter is eleven times greater than that of the earth4 ,the sun's diameter is only ten times greater than ,jupiter's4 ,his surface is one hundred and sixteen times that of the earth2 the sun's own surface is only a hundred times larger than his4 ,jupiter weighs more than three hundred times as much as the earth2 the sun weighs only six times more than ,jupiter4 ,at the equator his diameter is about ninety thousand miles2 but1 as the planet is much flattened at the poles1 the diameter from pole to pole is only a little more than eighty-four thousand miles4 ,this flattening is due to the very rapid spinning of the planet on its axis1 a motion that will always cause a plastic body to bulge at the equator1 and thus flatten at the poles4 ,illustration3 ,,jupiter1 ,,the ,,mammoth ,,member ,,of ,,the ,,solar ,,family--,,larger ,,than ,,all ,,the ,,other ,,planets ,,put ,,together ,this photograph shows the flattening at the poles and also the belts encircling the planet4 ,it was photographed at the ,yerkes ,observatory4 ,the force of gravity on ,jupiter is about two and one-half times greater than on the earth4 ,a fairy-like figure weighing here only a hundred pounds would be held to the surface of ,jupiter with a force equal to two hundred and sixty pounds4 ,this tremendous power makes ,jupiter the greatest disturbing body among all the planets4 ,he gives ,saturn a mighty pull when the two planets come near each other2 he draws some of the little asteroids five or six degrees out of their course when it carries them into the field of his influence2 and there are as many as thirty comets that have become permanent members of the solar system1 because through his great power of attraction he has made them captive4 ,jupiter is so much farther from the sun than we are that his orbit is about five times larger than that of the earth4 ,in consequence also of his greater distance from the sun1 he moves much more slowly than the earth4 ,his average velocity is about eight miles a second4 ,it requires more than four thousand days1 or nearly twelve of our years1 for him to make one revolution around the sun1 and he thus consumes more than ten thousand of his own days4 ,he travels through about one sign of the zodiac each year1 and is thus not very difficult to keep trace of1 since the signs and the constellations of the zodiac so nearly coincide4 ,his synodic period1 or the period from one opposition to another1 is a fraction less than three hundred and ninety-nine days1 or about one year and a little more than a month4 ,his daily motion in the skies is almost too small for us to detect it without observation for more than a day4 ,it is in one day about equal to one-sixth of the apparent diameter of the moon2 but in a month he has moved a distance about half as great as that between the two pointers in the ,big ,dipper1 as can be easily seen by comparison with the stars near him4 ,,jupiter',s ,,place ,,in ,,the ,,sky ,jupiter is now 7#aiab7 in the constellation ,scorpio1 and he will be in this region1 and thus a summer star1 for several years to come4 ,in #aiac he will be in opposition early in ,july1 and will then be in ,sagittarius1 not far from the little 8milk dipper10 and will be a gloriously beautiful object during all the summer4 ,he will be in opposition about ,august #aj1 #aiad1 in ,capricornus1 and will again be the most brilliant object in the summer sky4 ,in #aiae he will be in opposition a little after the middle of ,september1 and will then be situated on or near the eastern edge of ,aquarius1 where he will be a very distinguished star during all the charming evenings of late summer and the autumn4 ,he always seems particularly splendid when in this season of the year he reaches opposition4 ,the insistent brilliancy of his disc brings him then into view before the sun is fairly down2 and he hangs1 placid and alone1 in the southeastern sky during the autumn twilight1 and later in the evening shows to advantage his dominating beauty1 with ,antares on the west of him and ,fomalhaut below him1 no less charming in their own way1 but far less brilliant than this splendid planet4 ,in #aiaf1 when opposition will occur not far from ,hallowe'en1 ,jupiter will be about on the eastern border of the constellation ,pisces1 and1 rising then just as the sun sets1 will enliven the evening view for the rest of that year4 ,he will appear at his very best at this time1 for he will be at about his nearest to the sun2 and all that this situation can do for him in the way of enhancing his brilliancy may then be seen4 ,in #aiag he will be in opposition to the sun about the first of ,december1 in ,taurus2 and for the next few years he will be a winter star1 moving majestically along his path in the zodiac1 never more than one and a half degrees from the ecliptic1 and passing in turn the ,pleiades1 ,aldebaran1 ,castor and ,pollux1 and the little ,bee-hive in ,cancer4 ,there will be no opposition in #aiah2 but one will occur early in ,january1 #aiai1 when ,jupiter is in the eastern half of ,gemini2 and toward the middle of ,february1 #aibj1 another will take place1 when the planet is in ,cancer1 with ,castor and ,pollux1 the sparkling twin stars in ,gemini1 to the west of him4 ,during part of #aibj and all of the next three years ,jupiter will be journeying across ,leo1 ,virgo1 ,libra1 and ,scorpio4 ,he will be opposite the sun in #aiba1 a little after the middle of ,march2 in #aibb1 in the latter half of ,april2 and in #aibc1 toward the very last of ,may4 ,he will pass near ,regulus1 the sparkling star in the handle of the ,sickle1 in the summer of #aibj2 near ,spica in #aiba2 and he will not be far from ,antares in #aibc4 ,in #aibd ,jupiter's cycle of twelve years will be completed1 and he will be in opposition again early in ,july1 and situated near the western edge of ,sagittarius1 not far from where he was in #aiab4 ,these cycles do not repeat themselves exactly2 but the planet lacks only four days of having been in opposition eleven times during twelve of our years1 so that it is not difficult to keep track of him through a long series of years4 ,for exact dates1 such as one needs in a very close study of the planet1 an almanac must be consulted2 but this is not necessary for mere recognition1 which is all that is needed to enjoy the acquaintance of great ,jupiter4 ,every year ,jupiter is an evening star for more than six months4 ,for two months before opposition he rises somewhat after sundown2 at opposition he appears exactly at the setting of the sun2 and thereafter he is found in the evening sky1 appearing farther toward the west each evening1 until1 when nearing conjunction1 he is lost to our view for a time4 ,he is a morning star for an equal length of time1 and for about three months can be seen between midnight and six in the morning2 but much of the rest of the time he is obscured by the daylight4 ,jupiter retrogrades in his motion for about two months before and after each opposition2 but1 since he changes his place to the extent of only two and a half degrees a month1 the whole apparently backward movement amounts only to ten degrees a year4 ,still1 it is very interesting to watch him swing back and forth over this ten degrees before he starts out on each yearly journey4 ,,distance1 ,,light1 ,,and ,,heat ,jupiter is nearly five times farther from the sun than we are4 ,his mean distance from that orb is four hundred and eighty-three millions of miles4 ,his orbit is not so eccentric as that of ,mercury or of ,mars1 but the eccentricity is sufficient to make his distance vary by as much as forty-two millions of miles4 ,his distance is five hundred and four millions of miles when he is farthest from the sun1 and four hundred and sixty-two millions when he is nearest to it4 ,on account of his orbit being outside of ours1 we are at times nearer to him and at others farther from him than the sun ever is4 ,at his best situation when in opposition1 we are three hundred and sixty-nine million miles from him4 ,this is more than ten times farther than we are from ,mars at that planet's most favorable oppositions1 and yet ,jupiter is much brighter at such times than ,mars ever appears to be4 ,at the times of conjunction he is five hundred and ninety-six millions of miles from us1 but is still always brighter than a first-magnitude star like ,capella or ,vega4 ,although the distance of ,jupiter from us varies thus two hundred and twenty-seven million miles1 there is never in him the marked difference in brilliancy that we see in ,mars4 ,he is at all times so far away that the variation in distance does not count for as much1 though we can see the effect of it plainly enough1 even with the naked eye4 ,light1 with all its marvelous speed1 consumes more than fifty-three minutes in its journey from ,jupiter to the earth when we are most widely separated from him4 ,when we are nearest to him light comes to us from the planet in twenty minutes less time4 ,at his average distance from the sun it requires about forty-three minutes for light to pass from the sun to ,jupiter4 ,notwithstanding the sun's great power over ,jupiter in shaping his course1 it does not give him much in return for his subserviency4 ,so far as light and brilliancy are concerned1 it is to ,jupiter a very small sun indeed4 ,to an observer on ,jupiter the sun would not appear to be more than one-fifth as large as it seems to us4 ,the light it furnishes to ,jupiter is twenty-five times less than we receive2 and if the planet depended entirely upon the sun for heat1 his temperature would be more than two hundred degrees below zero1 ,fahrenheit4 ,there is every reason to believe that the little heat the sun gives to this mighty planet does not count for much one way or the other at the planet's present stage of development4 ,jupiter does not need the nourishing that the smaller terrestrial planets must have1 or die4 ,he is probably almost a sun himself4 ,we are not at all certain that the planet is even so far cooled as to have a solid surface4 ,if it has1 there is reason to think that the surface is at least red hot1 and gives to the planet a temperature higher than anything we have any comprehension of4 ,jupiter's atmosphere1 too1 is extremely thick and dense1 so that the planet is probably so protected that it gets very little heat from the sun and loses very little of its own4 ,it is certain1 however1 that this great planet is not so much of a sun as to shine by its own light4 ,the light we receive1 though it is very brilliant1 is reflected sunlight4 ,this is shown by the fact that the planet does not furnish light for its own satellites4 ,when they pass into its shadow the sunlight is shut off from them2 and if they receive any light from ,jupiter1 it is too dusky to be perceptible to us4 ,that the planet may have a red glow1 though1 is also suggested by the action of the satellites4 ,when they pass between us and ,jupiter they sometimes cast less of a shadow on his surface than would be expected1 thus indicating that the surface is not altogether dark1 though it may only dully glow rather than shine4 ,,day ,,and ,,night1 ,,seasons1 ,,and ,,atmosphere ,jupiter accomplishes one rotation in a little less than ten hours2 but1 curiously enough1 all parts of the planet do not rotate in the same length of time4 ,a day at the equator is nine hours and fifty minutes in length4 ,in some of the higher latitudes it is nine hours and fifty-five minutes1 and this notwithstanding the equator is so much larger in circumference than any other part and any one point on it has farther to go in a revolution4 ,as many as eight different rates of rotation have been observed2 and even in the same zones some parts seem to lag behind others1 taking a little more time to complete the rotation than other parts surrounding them4 ,this is another indication that ,jupiter is not a solid body4 ,the surface features are none of them permanent1 though some of them remain practically the same for years4 ,it is through this occasional stability of them that it has been possible to mark the planet's time of rotation4 ,in the matter of seasons ,jupiter has very little variety4 ,the axis of the planet is inclined but little more than three degrees to its orbit1 so that whatever amount of heat the sun's radiance affords must be very nearly uniform during the entire ,jovian year4 ,its distance1 too1 is at all times so great that there would be no appreciable change in temperature between its perihelion and aphelion positions4 ,there is every indication that ,jupiter has an extraordinarily dense and deep atmosphere4 ,it has been sometimes estimated to be as much as a thousand miles in depth1 and the spectroscope shows it to be heavily laden with vapor4 ,but beyond these very general facts not much is definitely known about it4 ,it is certain1 though1 that it is very different from our atmosphere4 ,the spectroscope shows in it elements1 or compounds of elements1 which are not familiar to us4 ,the enormous gravitative power of ,jupiter would enable him to hold gases rarer than the earth1 or the smaller planets like the earth1 ever acquired4 ,a molecule of gas would have to move more rapidly than thirty-seven miles a second to escape from ,jupiter4 ,the earth1 as we have seen1 cannot hold any gases moving faster than seven miles a second4 ,so there are many gases which may forever remain in ,jupiter's atmosphere and yet have never had a place in ours4 ,,surface ,,features ,seen through a telescope1 ,jupiter shows the loveliest variety of colors1 with the reddish ones always most conspicuous4 ,the slightly pink-tinted steady light that we get from the planet with the naked eye in no way suggests the turbulent1 flame-like aspect that a telescopic view opens to us4 ,the telescope also reveals very clearly that flattening at the poles which has already been spoken of4 ,with so dense an atmosphere as ,jupiter most likely has1 it is sometimes doubtful whether his surface can be seen by us at all4 ,but it is certain that we see something apparently much more dense and stable than an atmosphere is supposed to be2 and hence it is thought that1 in spite of its thickness1 the atmosphere may be only partially opaque1 and that it may be in some places even more or less transparent4 ,it does not seem probable that the markings on ,jupiter are wholly atmospheric4 ,some of them indicate that the substance we see has considerably more consistency than a mere gas4 ,the whole surface of the planet is covered with belts and spots of various colors and varying shapes4 ,the belted appearance is particularly marked4 ,it has been noticed for more than two hundred years1 and can be seen with a comparatively small telescope4 ,sometimes as many as twenty or thirty belts have been seen at one time4 ,all of them are parallel with the equator4 ,two broad red belts on each side of the equator1 called the tropical belts1 are very distinct1 and sometimes retain the same shape and color for months at a time1 though sometimes they change rapidly in both color and outline4 ,between them is the equatorial belt1 which is also a semi-permanent feature1 remaining often for a considerable period unchanged4 ,these belts1 and the spots that sometimes appear on and near them1 have been closely watched1 because about the equator1 and especially just south of it1 is the region of greatest activity on ,jupiter's surface4 ,one feature that more nearly suggests solidity and permanency than anything else on ,jupiter is the famous great red spot which lies in the southern hemisphere just below the southern tropical belt4 ,it appeared about thirty-five years ago1 in ,july1 #ahgh1 as a pale pink spot1 grew brighter for two or three years1 and then faded1 until1 at the end of two or three more years1 it was almost invisible4 ,in another year it came again1 and increased in brightness for five or six years4 ,then it grew a little fainter1 and has since remained a rather faint red spot1 but plainly visible4 ,in shape the great red spot is an immense oval as much as thirty thousand miles from east to west and seven thousand miles from north to south1 which gives it a surface four or five times as large as the land area on the entire earth1 and larger even than the whole surface of the earth including the oceans4 ,although retaining its own shape1 it seems to drift about among its surroundings1 showing that it is not attached to any solid surface2 and yet it has a suggestion of solidity in itself1 which was shown when it and another smaller spot were seen to be drifting toward each other1 and then finally to meet4 ,instead of colliding or going over or under1 they calmly drifted to one side and went around each other4 ,appearances such as this have suggested the idea that the great spot might be a continent in process of formation4 ,such an idea is at best a speculation2 but it would be interesting if it should prove that we are witnessing on ,jupiter the process through which our own earth must at one time have passed when its crust began to solidify in patches1 as one of the steps in the long period of evolution which has prepared it for our uses4 ,it is not at all certain that ,jupiter will ever be just like the earth4 ,the differences between its atmosphere and ours may have some influence in its development that we have little knowledge of at present1 and there are some other fundamental differences between the two planets which may in some way effect a difference in development4 ,but in a general way we know that the planet will in time become more condensed than it now is and will finally solidify4 ,whether the processes will be carried on in just the same way in which they have been here on the earth is not so certain4 ,,jupiter',s ,,system ,,of ,,satellites ,jupiter is the center of a superb system of satellites1 eight in number4 ,four of them were first seen in #afaj1 and have the honor to be the first heavenly bodies discovered by means of the telescope4 ,the fifth one was not discovered until #ahib4 ,the sixth was first seen in #aijd1 and the seventh in #aije4 ,after three years an eighth was discovered 7in #aijh74 ,when the first four satellites were discovered they were named respectively1 in the order of their distances from ,jupiter1 ,io1 ,europa1 ,ganymede1 and ,callisto4 ,ganymede is not only the largest of the four1 but is also the largest satellite in the solar system4 ,it is larger than ,mercury1 and not much smaller than ,mars4 ,callisto is next to ,ganymede in size1 and is about the size of ,mercury4 ,io is about the size of our moon1 and ,europa is not much smaller4 ,under very favorable conditions ,ganymede and ,callisto can be seen by the naked eye2 but a good many persons think they see the moons of ,jupiter when they see only some small stars in that region4 ,they are invisible to most people1 but probably could be seen oftener if it were not for the glaring light of the planet1 which more or less obscures anything so near it4 ,after the discovery of ,jupiter's fifth satellite1 astronomers seem to have become possessed with that dull spirit of orderliness such as is sometimes exhibited by city councils in substituting numbers for historic and beautiful names in designating streets4 ,no more of ,jupiter's satellites were given names such as might be appropriate for members of this ,jovian family2 but all were given numbers--the first four in order of their distance from ,jupiter1 the others in order of their discovery4 ,io1 ,europa1 ,ganymede1 and ,callisto are now designated1 respectively1 ,i1 ,,ii1 ,,iii1 and ,,iv1 while ,v1 ,,vi1 ,,vii1 and ,,viii have never had any designation other than these numbers4 ,the fifth satellite1 discovered in #ahib1 is the nearest to ,jupiter1 and the smallest of all his satellites4 ,its diameter is probably not more than one hundred and twenty miles1 but its exact size can be estimated only by the amount of light it reflects4 ,it is too small to show a measurable disc1 and cannot even be seen when it makes a transit across the planet4 ,it would seem then a mere speck1 if we could see it at all4 ,it makes one revolution about ,jupiter in less than twelve hours 7eleven hours and fifty-seven minutes71 and is only a little more than twenty-two thousand miles from the surface of the planet at the equator4 ,it appears to us as a star of about the thirteenth magnitude1 and cannot be seen except with a large telescope4 ,owing to the great curvature of the planet1 and to the satellite's being so near him1 it cannot be seen from the surface of ,jupiter beyond sixty-five degrees of latitude4 ,it moves faster than any other satellite in the solar system1 going at the rate of sixteen and a half miles a second4 ,it does not make a revolution in as short a time as ,phobos1 the little satellite of ,mars1 does1 but it has a much longer distance to travel and goes at a faster rate4 ,the fact that ,jupiter rotates in ten hours and the satellite makes a revolution around him in twelve hours results in the satellite's taking five of ,jupiter's days to cross from the eastern horizon to the western4 ,it would go through all its phases four times during that period if it were not that1 being so near the planet1 his huge form cuts off the sunlight from the little satellite for nearly one-fifth of the time1 and it is never seen 8full40 ,this satellite is very difficult for us to see on account of its diminutive size and its nearness to the shining disc of ,jupiter2 yet it was discovered by means of the telescope1 and not by photography1 as so many small bodies are discovered nowadays1 and by a man who thus far has not been able to see the fine line markings on ,mars1 which some other astronomers think they can see--a fact that is very interesting as showing the difference between observers even of great keenness of vision4 ,from this satellite ,jupiter would seem an enormous body1 nearly eighty-five times larger than our sun appears to us1 and1 no doubt1 a splendid object4 ,but the little satellite pays rather dearly for the view by suffering numerous and long-continued eclipses4 ,the sixth and seventh satellites are also very minute bodies1 measuring probably less than one hundred miles in diameter4 ,they circle about ,jupiter at a distance nearly thirty times more remote than our moon is from us4 ,they are about seven million miles from the planet1 and probably not more than barely visible from it4 ,it takes them two hundred and sixty-five days to make one revolution1 which is more than five hundred times as long as the period of ,jupiter's nearest satellite4 ,these two satellites are so nearly of one size and revolve so nearly in the same time and at the same distance from ,jupiter that they are thought to have had a common origin4 ,just what their relation is has not yet been determined4 ,the eighth satellite1 discovered in ,january1 #aijh1 is certainly no larger1 and is perhaps still more tiny1 than the sixth and the seventh1 though it is a little brighter than either one of them4 ,it is about three times farther away from ,jupiter than the seventh satellite1 and with eyes such as ours would not be visible from ,jupiter4 ,it shows to us as about a seventeenth-magnitude star1 which is almost at the limit of our vision with even the largest telescope4 ,it seems to revolve about ,jupiter in a direction exactly opposite to that of the other satellites--a retrograde motion that appears in the solar system in only two or three other cases and has not yet been entirely accounted for4 ,jupiter's satellites have played an important part in astronomical discoveries and investigations4 ,it was through observation of their transits that it was discovered that light occupied time in passing through space4 ,when ,jupiter was near us in his orbit1 the eclipses occurred too soon for their calculated time2 when he was farther away1 they occurred too late4 ,it was found that these irregularities were due to the fact that light is not transmitted through space instantaneously1 and further investigation showed that it travels at the rate of #ahf1djj miles a second4 ,the eclipses of ,jupiter's moons are carefully computed and recorded in the ,nautical ,almanac1 and it is through observations of them that chronometers are corrected at sea4 ,ganymede and ,callisto have been found to keep always the same face toward the planet1 as our moon keeps always the same face toward us2 and it is thought that all of ,jupiter's satellites probably do this4 ,the symbol of ,jupiter is 1 a hieroglyph for the eagle1 which was the bird of ,jove4 ,,xiv ,,saturn ,among the four planets that we commonly see1 the easiest1 perhaps1 to keep track of is ,saturn4 ,its peculiar aspect is very distinctly marked4 ,it appears as a large1 pale1 yellow star shining with a soft1 misty light that sometimes barely escapes being dull4 ,it is always as bright as a first-magnitude star1 but not always as bright as ,sirius1 and never as brilliant as ,mars1 ,jupiter1 or ,venus when they are at their brightest4 ,the general effect of it is as a large rather than a brilliant star4 ,the only time it loses these very marked characteristics is when it is drawing in toward the sun1 and thus nearing conjunction4 ,at such times we see it each evening lower in the rosy glow of the setting sun1 and more and more obscured and changed in color by the surrounding atmosphere4 ,then it sometimes seems as red as ,mercury1 and sometimes even twinkles a little in a sort of farewell gaiety as it backs away from us into the rays of the dazzling sun and finally disappears for a time from the evening sky4 ,proximity to the sun and entanglement in the atmosphere of the horizon has this effect more or less on all the planets1 as we know1 but it always seems unexpected in ,saturn1 because it is so out of keeping with his ordinarily large1 pale1 placid face1 which suggests softness and gentleness rather than vivacity4 ,but there is no mistaking the planet even under this aspect if we but stop to think where he is4 ,and it is through knowing where he is that it is so easy to keep track of ,saturn4 ,for nearly two years and a half1 on an average1 he remains in the same constellation1 passing slowly over about one degree a month1 or a little more than twelve degrees in a year1 occupying almost thirty years in making one circuit through the constellations of the zodiac4 ,one has1 therefore1 ample time to get well acquainted with him before he has wandered far from the position in which one first found him4 ,for nearly six months each year ,saturn shines as an evening star1 and1 returning each year as he does with such slight changes of position1 he comes to have something of the stability of a fixed star4 ,having seen him one year1 we can count on his returning the next only about thirteen days behind time1 and but little farther from his original position than twice the distance between the pointers in the ,big ,dipper4 ,the one degree a month which he travels along the ecliptic is toward the east1 except for a little more than two months before opposition1 and the same length of time afterward1 when he has the slight apparent retrograde motion due to our overtaking and passing him1 which has been explained4 ,with ,saturn this motion is so slight--only four degrees--that it does not put him much out of position1 and it is1 in fact1 not much noticed except by close observers4 ,he has all the time been going steadily on toward the east 7for the retrograde motion is only an apparent motion71 and the annual change of twelve degrees in position is always in this direction4 ,my first acquaintance with ,saturn was when he was traveling through ,pisces and ,aries1 where there are no first-magnitude stars to mark the path of the wandering bodies in the heavens4 ,it was then that ,i was most impressed with the fixity and reliability of his return4 ,every autumn then for five years we watched ,antares passing toward the west1 followed by the little 8milk dipper0 in ,sagittarius2 and then ,fomalhaut1 crossing the sky in the same direction1 though below the constellations of the zodiac2 and then turned our eyes toward the east1 knowing that the next bright body to come peeping over the tops of the trees would be ,saturn4 ,and when the first frosts began to strip the leaves from the trees we found the compensation that nature always gives when she destroys one beauty3 we could see earlier in the evening1 through the bare branches1 that lovely yellowish disc1 with its suggestion of aloofness and grandeur that is peculiar to it4 ,for the face of ,saturn1 while never what we would call cold1 has little in it of that bright1 warm1 friendly aspect which is at times so characteristic of ,venus1 ,mars1 and ,jupiter4 ,,around ,,one ,,circuit ,,of ,,the ,,skies ,,with ,,saturn ,saturn is now 7the autumn of #aiab7 in the first part of his path through ,taurus1 and he will be in that constellation during all of #aiac and the greater part of #aiad4 ,from #aiab to #aibj he will be a beautiful object in the winter sky1 threading his way slowly through that splendid galaxy of stars that blazes across the glittering sky peculiar to the cold winter nights4 ,he will pass between the ,pleiades and ,aldebaran1 and will be in opposition in that region on ,november #bc1 #aiab4 ,farther east in the constellation he will be in opposition in the first week of ,december1 #aiac4 ,almost on the border line between ,taurus and ,gemini he will be in opposition during the third week in ,december1 #aiad2 and1 as this is very near the perihelion point in ,saturn's orbit1 the planet will then be at his brightest4 ,in #aiae he will not be in opposition at all2 but sometime within the first two or three days of #aiaf he will reach that position1 and will then be well on in his journey across ,gemini4 ,for these four years--from #aiab to #aiaf--;he will be visible during the entire night1 at the times of his opposition1 and in his best condition4 ,the rings that surround him will then be placed so that we will get a broad expanse of light from them1 as well as from the planet itself1 which greatly increases its brightness4 ,saturn will then continue to move across ,gemini1 passing in the early part of #aiag under ,castor and ,pollux1 and very near to ,neptune--a meeting which1 unfortunately1 cannot be seen with the naked eye4 ,during this year 7#aiag7 he will begin his journey through the smallest of all the constellations of the zodiac1 ,cancer1 passing near the lovely cluster of stars we call the ,bee-hive1 and will reach ,leo early in #aiai1 where he will remain until about the end of #aiba4 ,while in this region he will be visible during the winter and all of the spring and the early summer4 ,all three of these constellations--,gemini1 ,cancer1 and ,leo--while seen in the winter1 are particularly lovely in the spring4 ,gemini1 in the beautiful evenings of ,may1 hangs with its two splendid stars in the northwest above the setting sun2 and with the soft face of ,saturn near them1 these stars will be more than ever charming in the two seasons that the planet remains with them4 ,in #aiag ,saturn will be in opposition in the region of ,gemini1 about the middle of ,january4 ,in #aiah opposition will occur about the last of ,january1 and ,saturn will then be in ,cancer4 ,the next year he will be in opposition sometime during the second week in ,february1 and will then be situated between the ,bee-hive1 in ,cancer1 and the brilliant first-magnitude star ,regulus1 in ,leo4 ,the next two oppositions will be in ,leo1 about thirteen days later each year4 ,saturn will then pass during the first half of #aibb into ,virgo1 which is the largest of all the constellations1 and he will remain there until three oppositions have taken place1 about thirteen days later each year4 ,about a year after passing ,spica1 the white1 sparkling1 first-magnitude star in ,virgo1 ,saturn will enter ,libra1 crossing that constellation near the lower part of the square in it4 ,from there he will go through ,scorpio and ,sagittarius1 passing above ,antares and the 8milk dipper10 and in about #aicb will have reached that comparatively starless region which includes a part of ,sagittarius and all of ,capricornus1 ,aquarius1 ,pisces1 and ,aries4 ,for the next nine and a half years he will give distinction to this part of the heavens1 and thus complete his circuit of twenty-nine and a half years1 and1 with never resting1 never changing movement1 will start on a new round1 with a new generation of eyes following his fair face along the great circle of the ecliptic4 ,saturn is brightest when he is in ,taurus1 not far from ,gemini1 as he will be in #aiad1 and again when he is in ,scorpio1 as he will be between fourteen and fifteen years later4 ,the recurring times at which we can get an evening view of him at his greatest brightness thus alternate between midwinter and midsummer4 ,he is least bright when he is in the last half of ,leo and when he is in that part of ,aquarius above ,fomalhaut4 ,between these positions he gradually waxes and wanes in brightness1 changes that are largely due to the position of his rings4 ,,distance ,,and ,,size ,saturn is almost twice as far from the sun as ,jupiter1 and between nine and ten times farther than we are4 ,his mean distance from the sun is eight hundred and eighty-seven million miles2 but his distance varies nearly one hundred million miles between perihelion and aphelion4 ,his orbit is only a trifle more eccentric than that of ,jupiter1 but the variation in miles is so much greater because the orbit is so much larger4 ,his average distance from the earth at opposition is seven hundred and ninety-four million miles1 but at the most favorable opposition it may be fifty million miles nearer than that4 ,at conjunction his average distance is nine hundred and eighty million miles2 but his greatest possible distance at such times may be as much as one billion miles4 ,when he is in this situation it takes light a little more than an hour and a half to pass from him to us4 ,at his nearest we receive light from him in about an hour and six minutes4 ,at his average distance from the sun1 light requires about an hour and twenty minutes to go from one to the other4 ,while ,saturn is next to ,jupiter in size among the planets1 he is not as large as ,jupiter by two-thirds1 but his mass is almost three times greater than that of all the other planets put together except ,jupiter4 ,it is ninety-five times greater than that of the earth4 ,in diameter ,saturn is #gb1ggb miles2 but it is more flattened at the poles than any other planet1 and in consequence there is a difference of nearly seven thousand miles between its polar and its equatorial diameters4 ,the density of ,saturn is less than that of any other planet1 and it is ten times less than that of the earth4 ,no other planet is less dense than water2 but ,saturn would float in water1 and is not more dense than cork4 ,on account of its mass its gravity is greater than that of the earth by about one-tenth4 ,this is not enough to make a very interesting difference in the weight of objects on ,saturn and on the earth4 ,the average person weighing one hundred and fifty pounds here would weigh only one hundred and sixty-five pounds on ,saturn4 ,the numerous penny-in-the-slot weighing-machines vary almost that much4 ,saturn has eighty-three times more surface than the earth1 and more than seven hundred and fifty times the earth's volume4 ,,surface ,,aspects ,,and ,,constitution ,it is not at all certain that ,saturn1 more than ,jupiter1 has any solid surface4 ,indeed1 it is almost certain that it has not4 ,it is surrounded by an atmosphere of great density1 and we do not at any time see the surface of the planet4 ,it is believed probable that it is at least largely in a liquid state1 if not to a great extent even gaseous4 ,the planet is certainly not in any way dependent on the sun for the extraordinary heat that everything indicates it to have1 and its surface is brighter than it is believed it could be if shining only by the reflected light of the sun4 ,this does not mean that ,saturn is self-luminous2 but it is nearly certain that it is extremely hot and glowing1 and its brightness may be in part due to its own internal fires and the extremely luminous and dense atmosphere that surrounds it4 ,it receives one hundred times less heat and light from the sun than we do4 ,if it depended entirely upon the sun for its heat1 the temperature would be nearly three hundred degrees below zero1 ,fahrenheit4 ,it is probably not only very hot itself1 but its heavy atmospheric envelope perhaps allows comparatively little heat to escape4 ,its surface is belted and spotted somewhat after the manner of ,jupiter's1 but1 being so much farther from us than ,jupiter1 it does not disclose its surface features with the same distinctness4 ,apparently it is much less turbulent than ,jupiter2 but even this we are not quite certain of1 and it may seem more placid because we do not so well see its agitations4 ,like all the outer planets1 it differs in its constitution from the earth and the other inner planets4 ,its atmosphere contains compounds with which we are not familiar1 and the body of the planet itself is rarer and lighter1 and less condensed1 and in a much earlier stage of evolution than the earth and the small planets so comparatively near us4 ,,day ,,and ,,night ,the length of ,saturn's day1 or its period of rotation on its axis1 is about ten hours and a quarter4 ,like ,jupiter1 it has slightly different rates of rotation in different latitudes1 thus showing its lack of solidity4 ,the rate of rotation has been determined1 as in the case of ,jupiter1 by observation of the spots on its surface1 which1 while they are not exactly permanent1 yet remain apparently in the same positions for months and even years at a time1 and are thus sufficiently stable to measure a rotation of so short a time as ten hours4 ,whirling over at this rate would cause the sun to appear to skim across the sky very swiftly as viewed from ,saturn4 ,in size1 it would not seem more than three times as large as ,venus at her brightest seems to us1 and every minute it would cover a distance about equal to the diameter of the full moon as we see it4 ,in an hour it would seem to move more than six times as far as the distance between the 8pointers40 ,at the time of ,saturn's equinox the little five-hour day1 followed by the equally short night1 must present a lively aspect with the sun racing thus swiftly across the sky in daylight and the stars sweeping as swiftly over at night4 ,if things remain as they now are1 it will be a splendid panorama for the people there when1 in the far-distant future1 ,saturn may have cooled and solidified sufficiently to maintain life somewhat as we know it4 ,the earth1 though1 and ,venus and ,mars would be from ,saturn only telescopic objects to eyes like ours1 and ,jupiter no brighter than he is to us4 ,thus does our brother ,saturn pay the price of his remoteness from the rest of the solar family4 ,,the ,,rings ,,and ,,moons ,,of ,,saturn ,but the circling stars and the swift-moving sun are the least part of the splendid spectacle that might be seen from ,saturn4 ,he is surrounded with no less than ten moons of more or less imposing size1 and in addition has three rings circling around with him1 composed of myriads of small satellites1 together forming a band the outer diameter of which is something more than twenty-one times broader than the diameter of the earth4 ,these are the famous rings of ,saturn1 the only objects of their kind in the solar system1 intensely interesting to scientific observers1 wonderful to the curious1 and splendidly beautiful to everybody4 ,it is this profusion of rings and moons that entitles ,saturn to be called1 as he often has been1 the most spectacular of all the planets4 ,the outer ring is nearly ten thousand miles broad1 and is separated from the next one by a space of about seventeen hundred miles4 ,the second ring is nearly eighteen thousand miles across4 ,it is very bright on the outer edge1 but gradually grows less so1 until1 with a not very perceptible division1 it fades into the inner ring1 which is but slightly luminous1 and is called the crape ring4 ,this is about nine thousand miles broad and nearly ten thousand miles from ,saturn4 ,this gradual fading of the rings to a dusky hue toward the center1 and then the blackness of the space between them and the planet1 gives them from certain points of view a nest-like appearance2 and my first impression of ,saturn1 when ,i saw him through the telescope1 was that he was nestling in a concave body of light--an appearance that is intensified by his extreme flatness at the poles4 ,notwithstanding the imposing breadth of these rings1 they are less than a hundred miles in thickness4 ,they are1 in fact1 nothing more than an untold number of tiny satellites revolving about ,saturn in the same plane and close enough together to appear1 at the distance they are from us1 as if they were one body4 ,just how close they are together1 and how they appear when near by1 we do not yet know4 ,it was first shown by mechanical laws that they must be composed of separate bodies2 the spectroscope shows that they are2 and it has recently been thought that they have even been seen to be so through a telescope4 ,being all in the same plane1 they form a flat1 broad1 thin ring1 so thin that when the edge of the ring is turned toward us we cannot see them at all4 ,we never see them at their full breadth4 ,if we did1 ,saturn would be much brighter at times than he ever is4 ,the plane in which they revolve is the plane of ,saturn's equator2 and the axis of ,saturn1 with the rings1 has a tilt of twenty-seven degrees in his orbit4 ,the result of this is that at the time of ,saturn's equinoxes the edge of the rings is turned toward us1 and they practically disappear4 ,half-way between the equinoxes they are open again as far as they ever are to our view4 ,this is why ,saturn alternates in brightness4 ,the times of his equinoxes occur every fourteen and eight-tenths years1 and he is then alternately in ,leo and ,aquarius and is least bright4 ,the times at which the rings are most open occur at intervals of the same length1 and he is then alternately in ,scorpio and ,taurus and at his brightest4 ,illustration3 ,,saturn ,,and ,,its ,,rings ,photographed at ,mt4 ,wilson by ,e4 ,e4 ,barnard1 the six exposures being made on one plate4 ,it is believed that ,saturn's rings were never a part of the planet1 but are mere particles of cosmic materials which happened to be left over1 and which he has gathered up by his force of gravity and compelled to revolve about him4 ,saturn1 more fortunate than ,jupiter1 has escaped the unimaginative naming of his moons by number1 though one would think that1 having such a numerous offspring1 a shortage in names would be more likely to occur in his than in any other planet family4 ,they all have names more or less connected with the great god whose name the planet bears1 and are1 in order of their distance from ,saturn3 ,mimas1 ,enceladus1 ,tethys1 ,dione1 ,rhea1 ,titan1 ,hyperion1 ,japetus1 ,phbe1 and ,themis4 ,the largest and brightest of them all is ,titan4 ,it is larger than our moon1 which is one of the large moons in the solar system1 or than ,mercury1 and is not much smaller than ,mars4 ,it is more than three-quarters as large as all the other moons of ,saturn put together4 ,naturally1 it was the first to be discovered1 and was under observation as long ago as #afee4 ,rhea and ,japetus are next in size1 and were discovered in #afga-gb2 ,dione and ,tethys were both discovered in #afhd1 and ,enceladus and ,mimas in #aghi4 ,until #ahdh seven moons were all that were known to belong to ,saturn4 ,in that year little ,hyperion1 whose diameter1 it is thought1 can hardly exceed two hundred miles1 came into our view4 ,a little more than fifty years later 7in #ahih7 ,phbe made her bright mark on a photographic plate at ,harvard1 and was caught4 ,by tracing her from one plate to another her orbit was computed1 her probable size determined1 and practically all that is known about her was found out before she was seen1 which was not until #aijd4 ,she is not much larger than a good-sized mountain1 but is a unique and interesting little satellite that1 far outside of the paths of any of the other moons1 circles in an eccentric orbit around ,saturn in an opposite direction from the rest of the satellites1 and thus gives rise to many interesting astronomical speculations4 ,themis1 also a tiny body1 was discovered in the same way in #aijf1 and is thought to be the smallest body in the solar system4 ,titan is the only one of this group of satellites whose true disc we can see even with a telescope4 ,only one other 7,rhea7 can be seen in transit across the planet4 ,the others are not much more than bright points of light1 while ,phbe and ,themis are almost at the limit of visibility4 ,on account of their great distance from the sun ,saturn's moons are1 of course1 not very bright1 and all of them put together do not give one-tenth as much light to ,saturn as we receive from our moon4 ,but1 such as they are1 they may some day be very useful to ,saturn as a means of illumination4 ,receiving as he does a hundred times less light from the sun than we do1 he may be some day much in need of the light reflected from all his rings and moons4 ,,seasons ,the seasons on ,saturn are somewhat like ours in the succession of spring1 summer1 autumn1 and winter2 but the inclination of its axis to its orbit being twenty-seven degrees instead of twenty-three and a half1 as ours is1 each season is much more accentuated than ours4 ,the sun climbs higher during the northern summer1 and sinks correspondingly lower during the winter4 ,but in length ,saturn's seasons are very different from ours4 ,like his year1 they are about twenty-nine and one-half times as long as ours4 ,each one is more than seven years long4 ,even the agreeable seasons might grow monotonous to one in that time2 but to be spinning through the rapidly alternating days and nights of ,saturn during seven long years of winter is a situation that one does not care to contemplate4 ,it is with world personalities as with human personalities3 however much we may admire their superior grandeur1 when we consider details we would not change places with them4 ,the symbol of ,saturn is an ancient scythe 771 which gets its appropriateness from the fact that the deity of that name was the special protector of agriculture4 ,,xv ,,uranus ,venus1 ,mars1 ,jupiter1 and ,saturn1 brilliant beauties that they are1 have always been distinguished features of the heavenly view4 ,the records of ,mercury do not go back so far as those of these more easily seen planets1 yet there is no reason to think that he has not been always known1 though less widely1 perhaps1 than the four planets more frequently in view4 ,to ,uranus belongs the distinction of being the first planet that was discovered--a distinction that one cannot help but feel was too long delayed1 for it did not come until #agha4 ,for ages and ages his lovely pale beams had been shining down upon us from his little disc1 no fainter in brilliancy than many a sixth-magnitude star 7a degree of brightness which we think is within the limit of good vision1 even in these days71 and no human being had been conscious that this bright body was only another member of the solar family1 circling with the rest of us around our parent1 the sun1 and having nothing in common with the far-off stars among which we had numbered him4 ,nineteen times he had been charted as a fixed star before his identity was suspected1 and after he became known to us as a planet he was1 by means of these charts1 traced back for one hundred and thirty years1 and much information was thus gained concerning his orbit and movements4 ,uranus was not1 however1 discovered through observation of his movement among the stars4 ,a view of his actual disc was caught by the musician and astronomer1 ,herschel1 as he gleaned with his telescope in that part of the sky where the planet lay1 one hundred and seventy-one years after the invention of that aid to vision4 ,it was at first thought that a comet had been discovered1 but later investigation showed a much more important member of the solar system1 and the discovery of a new planet was announced4 ,george ,,iii4 was then ,king of ,england1 and the loyal ,herschel called the planet ,georgium ,sidus in honor of that monarch4 ,fortunately1 the world-wide interest in this newly discovered body saved it from so local an appellation1 and it finally came to be called after ,uranus1 the father of ,saturn1 a name somewhat more in keeping with its place among the planets4 ,in ,england1 however1 a very commendable loyalty to ,herschel has resulted in the planet's sometimes being called ,herschel1 after its discoverer1 and we see this name often in ,english books on astronomy1 especially the older books2 but ,uranus is now the generally accepted name4 ,the symbol of the planet as it appears in all almanacs--at least in all ,english almanacs--is a capital ,h with a planet swinging from the cross-bar in the letter1 thus 4 ,and to this extent the discovery of the planet by ,herschel is commemorated4 ,in ,american almanacs the symbol is contracted into this figure 4 ,it is a matter for regret that ,uranus does not come more easily within our view2 for he is a very beautiful planet1 pale green in color1 and unlike any of the others in his aspect4 ,there are1 however1 very few persons nowadays who can see him without the aid of at least a small glass1 and to most of us he must ever remain a body with which we can have no personal acquaintance4 ,none the less he must have an interest to us such as attaches always to anything so closely related to us1 and sharing with us a common origin and a common destiny4 ,to those who have unusually keen vision--or a small telescope--there will be much pleasure in viewing the planet4 ,but even to those who have not these facilities for seeing1 it ought to be interesting to know in what region of the skies this far-off member of our family dwells1 what his wanderings are1 and something of his personality and habits4 ,it requires a few days more than eighty-four years for ,uranus to make one revolution around the sun1 so that he moves even more slowly than ,saturn from one constellation to another2 and if we could only see him more easily1 he would be scarcely more difficult to keep track of than a fixed star4 ,he remains in each constellation somewhere near seven years and his change of place in the skies amounts in one year to but little more than four degrees1 which is less than the distance between the pointers4 ,since ,uranus was discovered he has made one circuit of the skies1 which he finished in #ahfe1 and he is now 7#aiab7 more than half-way around on another4 ,his position now is in ,capricornus1 nearly twenty degrees east of the 8milk dipper0 in ,sagittarius1 and for the next quarter of a century he can be seen by any who have eyes1 or a glass1 to accomplish this during the summer evenings4 ,each year he will be about seven degrees farther east4 ,he is1 however1 still pretty far south of the equator1 and not so easily seen as he will be when he reaches that part of the ecliptic which runs somewhat higher in the skies4 ,even an opera-glass will bring ,uranus into the view of many persons4 ,his path deviates very little from the line of the ecliptic--never quite so much as half a degree4 ,the knowledge of this makes it less difficult to find him4 ,the synodic period of ,uranus is about three hundred and sixty-nine days1 so that an opposition occurs about four or five days later each year4 ,he was in opposition this year 7#aiab7 on ,july #bdth4 ,in #aiac an opposition will take place on ,july #bith1 and in #aiad on ,august #b;d1 and oppositions will occur about four days later each year thereafter4 ,uranus is twice as far from the sun as ,saturn is1 and nineteen times as far as the earth4 ,its mean distance from the sun is #a1ghd1gcb1jjj miles1 and at this distance more than two hours and a half would be required for light to travel from the sun to the planet4 ,viewed from the planet1 the sun would appear only about two and a half times larger than ,jupiter appears to us1 and the earth would be a very small telescopic body1 if1 indeed1 it would be visible at all4 ,even at this great distance from the sun1 and with the sun showing so small as it does1 the planet would still have more than a thousand times as much light as we get from our moon1 and so in this respect might be fairly comfortably provided for even for eyes constructed like those of human beings4 ,the heat the sun's radiant energy furnishes to ,uranus is1 from our point of view1 almost a negligible quantity4 ,if there were no other source of supply1 the normal temperature of the planet would be more than three hundred degrees below zero1 ,fahrenheit4 ,there is no reason to think1 however1 that this is the temperature that prevails on ,uranus4 ,as far as we can tell1 it has a dense and extensive atmosphere1 and probably very considerable internal heat4 ,uranus is smaller than either ,jupiter or ,saturn2 but it is much larger than ,mars1 ,venus1 ,mercury and the earth combined4 ,its diameter is nearly thirty-three thousand miles4 ,its volume is sixty-five times as great as that of the earth2 but its mass is only about fourteen times the mass of the earth1 which shows it to be a very much expanded body4 ,it is slightly more dense than water1 but only about two-tenths as dense as the earth4 ,its force of gravity is small for so large a body--only about nine-tenths that of the earth4 ,there is every indication that the planet is not a solid body at all1 and that it is1 perhaps1 largely vapor4 ,we undoubtedly cannot see the surface of it2 but through the telescope it faintly shows the same belted appearance that we see on ,jupiter and on ,saturn1 though it is difficult to see the belted region1 which is near the equator1 because the axis of the planet is so inclined to its orbit that much of the time the poles are pointed almost toward us4 ,the spectroscope indicates something of the same materials in its atmosphere that the other large and faraway planets have1 and there is no reason to doubt that the planet is in a much earlier stage of development than any of the terrestrial planets4 ,we really know nothing certainly about the rotation of ,uranus2 but there seems to be some indication that1 like ,jupiter and ,saturn1 it revolves swiftly--in perhaps ten or twelve hours1 and hence has a very short day and night4 ,the great inclination of its axis must make its seasons so abnormal1 from our point of view1 that it is difficult to understand what they are4 ,moreover1 the planet is1 at this stage of its development1 so far from being a habitable body1 for beings such as we know anything about1 that the subject of its seasons seems not very important or interesting4 ,it seems but fitting that this vapory1 pale green planet should have satellites with the fairy names of ,ariel1 ,umbriel1 ,titania1 and ,oberon4 ,one can forgive a good many utilitarian feats in nomenclature for the sake of these charmingly appropriate names for the satellites of ,uranus4 ,titania and ,oberon were discovered in #aghg by ,herschel1 the discoverer of the planet4 ,they are not very much farther from ,uranus than our moon is from us1 and are easily seen with a telescope4 ,titania1 the nearer to ,uranus and the larger1 is probably about one thousand miles in diameter2 and ,oberon is not very much smaller4 ,in #aheb ,umbriel and ,ariel were discovered4 ,they are both smaller and nearer to ,uranus than either of the two first discovered1 and are seen with considerable difficulty1 because of their proximity to the larger and brighter body of the planet4 ,there is not1 however1 very much difference between any of the four in real brightness4 ,,xvi ,,neptune ,it is rather curious to what extent we have a feeling of kinship with ,neptune1 notwithstanding he dwells forever in far-off space where we cannot expect even to have a glimpse of him without the aid of a telescope4 ,uranus1 the other very distant planet1 is so nearly within the limit of ordinary vision that we have always a hope that1 by some lucky chance of situation or atmosphere1 we may some day be able to see him face to face1 and know for ourselves what manner of planet this is which1 though a member of our own cosmic family1 remains always just beyond easy exchange of glances with us2 and so we in a measure keep a lookout for him that gives us a sense of his reality4 ,with ,neptune there can be no feeling of this sort to keep us with a lively interest in him1 and yet he is hardly less real to us than ,uranus1 and we have a more intimate sense of nearness to him than we have for any fixed star4 ,far away as he is1 the distance between us is short compared with the many trillions of miles farther that we must go to reach the nearest star1 and in thinking of him we always have a sense of this4 ,then1 however aloof he may keep himself from this cozy little bunch of planets near the sun1 of which the earth is one1 he is still of the same parentage with us1 and his life history is part of our family history1 so that we can never feel indifferent to what concerns him4 ,close as ,neptune is to us in kinship and distance1 as astronomical distances go1 we never knew of his existence until sixty-six years ago4 ,he is to us almost a recent arrival in the solar domain1 but we know that he has been here as long as we have2 and whether he was detached before we were from the great nebula which gave birth to us all1 or at about the same time1 we know that for long ages before there were eyes on the earth to see him he was1 as he still is1 circling slowly and majestically around our common center of control4 ,the discovery of ,neptune in #ahdf created truly a sensation in astronomical circles4 ,and1 unlike most sensational happenings1 it fully justified the extreme interest it aroused4 ,the computation that led to it was a mathematical triumph1 and the final result was a most splendidly convincing proof of the theory of gravitation4 ,for the place of this hitherto unknown planet was found by means of computations based on the fact that at certain times ,uranus went a little out of his way1 thus showing some disturbing body outside of his orbit pulling him slightly from the course he would otherwise take4 ,the deviation was not much--only about one and three-fourths of a minute1 which is equal to about one-seventeenth of the apparent diameter of the moon1 or one-sixth of the distance between ,mizar and ,alcor1 situated at the bend of the handle of the ,big ,dipper1 two stars that it is difficult for some eyes to separate4#g ,but this slight irregularity of ,uranus was enough to set at least two able men at work in an effort to locate the disturbing cause4 ,these two men were ,adams1 of ,england1 and ,leverrier1 of ,france4 #g ,see1 in ,the ,friendly ,stars1 8,the ,seven ,stars of the ,dipper40 ,the result of ,adams's work was announced to the ,astronomer ,royal in ,england in the autumn of #ahde2 but the actual search for the planet in the place predicted was delayed until the following summer4 ,in the mean time ,leverrier had completed his work and had communicated with astronomers in ,berlin1 directing them where to look for the planet4 ,the facilities for that sort of work were then better in ,berlin than in ,england2 and within half an hour after the search was begun1 on the night of ,september #bc1 #ahdf1 the new planet was discovered a little more than half a degree from the exact position ,leverrier had found for it4 ,it was first recognized as having a sensible disc1 and within a day its motion was apparent4 ,no wonder the astronomical world was thrilled by this achievement6 ,although the planet was actually discovered by following the directions of ,leverrier1 it was found that it might have been seen months before if the ,english astronomers had shown more promptness in using the computations of ,adams2 and there has always been a disposition among astronomers1 both in ,france and in ,england1 to give both men credit for their extraordinary achievement1 though1 naturally1 there is somewhat more stress laid upon the work of each in his own country4 ,the newly discovered body was at first named for its discoverer1 ,leverrier1 but a sense of justice to ,adams prevailed to such an extent that in the end a less commemorative name was chosen1 and the planet was called after ,neptune1 the son of ,saturn and the brother of ,jupiter--a name more fitting1 on the whole1 for a member of this planet family1 whose other members all bear the names of some of the ancient deities4 ,the trident 771 ,neptune's three-pronged spear1 is the symbol of the planet4 ,the mean distance of ,neptune from the sun is more than two and a half billion miles 7#b1gij1jjj1jjj71 and his orbit is so nearly circular that the variation between his perihelion and aphelion distance is only about fifty million miles4 ,his orbit is1 in fact1 less eccentric than that of any other planet except ,venus4 ,his immense distance from the sun1 of course1 deprives him of any great amount of heat or light from that source as compared with the other planets4 ,the sun would appear to an observer on ,neptune a little smaller than ,venus appears to us4 ,but so great is the intensity of its radiance that even as so diminutive a sun as that it would give to ,neptune more than six hundred times as much light as our full moon gives to us4 ,this1 however1 would be as much as nine hundred times less light than we get from the sun4 ,such light as the planet receives from the sun reaches it after a journey of a little more than four hours4 ,of the heat the planet has1 either inherent or acquired from the sun1 we do not know much4 ,the normal temperature at that distance from the sun would be more than three hundred and sixty degrees below zero1 ,fahrenheit1 and there is not much to indicate in what state the planet is with reference to its own heat4 ,investigations thus far made do not show it to be so intensely hot as ,jupiter and ,saturn undoubtedly are2 but with its heavily vapor-laden atmosphere it could not have the frigidity normal to a black1 unprotected body at its distance from the sun4 ,neptune is thought to have an immense atmosphere1 and1 like the other outer planets1 one of a composition not wholly familiar to us4 ,consequently we do not know as yet just what this atmosphere does for the planet4 ,it has a fairly good reflecting power1 though the planet1 on the whole1 is darker in color than ,jupiter or ,saturn4 ,its color is of that bluish cast which sometimes suggests a leaden appearance4 ,the color1 as well as the fact that ,neptune is denser than any of the other outer planets1 indicates that it may be in a more advanced stage of development than at least ,jupiter and ,saturn are1 and perhaps than ,uranus is4 ,that ,neptune has made greater progress toward solidity 7though it is still very far from that state7 than the other outer planets is suggested also by its size2 for1 as we have seen1 the smaller planets develop more rapidly than the larger ones4 ,the diameter of ,neptune is a little less than thirty thousand 7#bi1hbg7 miles4 ,the planet is somewhat smaller1 therefore1 than ,uranus1 and much smaller than ,jupiter or ,saturn4 ,but as compared with the earth1 the largest of the inner planets1 it is a vastly greater body4 ,its mass is seventeen times more than that of the earth2 its surface is as much as sixteen times more extensive than the earth's2 and its volume is more than eighty times greater than the volume of the earth4 ,of the time of ,neptune's rotation on its axis very little is known4 ,that little1 however1 indicates a slower rotation than the other planets seem to have1 and the alternations of day and night on ,neptune are1 therefore1 probably less swift than on ,jupiter and on ,saturn4 ,the planet is too far away for us to see its surface markings with any distinctness1 but there are indirect processes by which we can get approximate information concerning the facts about rotation4 ,one of these processes is by observation of the motions of the satellites4 ,of these useful bodies ,neptune1 fortunately1 has one--a very excellent moon about the size of our own4 ,it has some eccentricities1 such as revolving about the planet in the opposite direction from that which the more conventional satellites follow1 and having an orbit a good deal inclined to the plane of the equator of the parent body4 ,but it is a very interesting moon to astronomers1 and will no doubt in time help to make clear some things in the history of ,neptune which are now not quite understood4 ,being so far from the sun1 ,neptune moves1 of course1 very slowly in comparison with the nearer planets1 though his speed is at the rate of three and a half miles a second1 which1 after all1 does not denote any high degree of sluggishness4 ,his change of position in the sky amounts to a little more than two degrees a year2 so that in an ordinary lifetime he does not make any very great progress along the zodiac4 ,when ,neptune was discovered he had just left the constellation ,capricornus1 and in the sixty-six years that his movements have been followed he has passed through ,aquarius1 ,pisces1 ,aries1 ,taurus1 and is now 7#aiab7 in ,gemini1 very near ,castor and ,pollux4 ,the time required for his circuit around the sun is nearly one hundred and sixty-five 7#afd4f7 years1 so that he remains for about thirteen years in each constellation4 ,he will complete one sidereal period1 dating from the time of his discovery1 in the year #bjaa4 ,the apparent motion of ,neptune is direct a little more than six months in the year1 and retrograde a little more than five months1 so that it seems to present the old mental arithmetic problem of the climber that fell back so much every time after he had climbed a certain number of feet4 ,but the falling back in the case of ,neptune is an illusion1 as we know4 ,he keeps straight on in his journey1 as we may see if we watch him from year to year1 and his change of position is so slight during any year that the change of direction is hardly noticeable4 ,neptune is as bright as an eighth-magnitude star1 and it is possible to see him with a good field-glass4 ,the difficulty is in distinguishing him from a star1 for his disc does not show except through a telescope4 ,if one has such a glass1 however1 it will be worth while to direct it toward that part of the ecliptic just under ,castor and ,pollux any time within the next two or three years1 and a sight of this yet strange brother planet may be the reward4 ,he will be in opposition on ,january #ad1 #aiac1 and thereafter about two days later each year4 ,,xvii ,,the ,,little ,,planets1 ,,or ,,the ,,asteroids ,the asteroids1 or minor planets1 are situated almost wholly in the vast space between ,mars and ,jupiter4 ,their orbits are very irregular1 both as to shape and situation2 but1 so far as is known1 only two of them pass beyond the orbit of ,jupiter1 and only one has been discovered which at any point in its journey around the sun comes nearer than the orbit of ,mars4 ,the minor planets are called by astronomers almost indifferently asteroids or planetoids4 8,asteroids0 is probably the name by which they are most popularly known4 ,but because they are in fact simply little bodies that revolve about the sun as the planets do1 8planetoids0 seems to be more truly descriptive of them1 and it is the word ,i have chosen to use here4 ,it was early noted that1 except in one instance1 the planets seemed to show in their distance from the sun something like a mathematical progression4 ,struck by this appearance1 an astronomer named ,bode worked it out into a formula1 known ever since as ,bode's law1 though the idea seems to have originated with another astronomer4 ,one almost always sees it mentioned in any work dealing with this phase of planetary history1 and it is especially interesting because of the part it played in the discovery of the planetoids4 ,it was as follows3 ,beginning with nothing for ,mercury1 add three for ,venus1 twice three1 or six1 for the earth1 twelve for ,mars1 and continue thus to double the number for each planet out to and including ,saturn4 ,then to each one of the numbers so obtained add four1 and the numbers resulting will very nearly represent the relative distances of the planets from the sun4 ,thus3 #j #c #f #ab #bd #dh #if #aib #chd #d #d #d #d #d #d #d #d #d ---------------------------------------- --- #d #g #aj #af #bh #eb #ajj #aif #chh ,the exception was that at the fifth number1 #bh1 there was no planet to correspond1 and ,jupiter was nearly twice as far away from ,mars as it should have been to conform to the law1 thus leaving room for another planet to occupy the allotted position and fill out this very beautiful progression4 ,about nine years after this law was set forth ,uranus was discovered circling out in space far beyond ,saturn1 and was found to conform to the law in a most satisfactory manner1 its distance being approximately twice that of ,saturn4 ,with such close accord between the actual distances and the prescribed distances of the planets from the sun1 and with the one exception leaving almost exactly the space allotted by ,bode's law for another planet1 astronomers naturally had a very strong feeling that there must be another planet between ,mars and ,jupiter4 ,they accordingly set to work to prove this1 if possible1 and to find what had become of this lost member of the planet family1 if it ever existed4 ,as a result of this work1 on ,january #a1 #ahja1 the first planetoid was discovered1 and in rapid succession many like it were found1 until now many hundreds are known to astronomers4 ,their discovery seemed at first almost a certain confirmation of ,bode's law1 and the fact that where one large planet should have been found there proved to be such a swarm of small ones could be accounted for in no other way than to suppose that something had happened in the making of the planet4 ,at any rate1 the promulgation of ,bode's law was the direct cause of the search for the missing planet which led to the discovery of the planetoids4 ,and this is the only reason why ,bode's law has continued to be mentioned in the history of the planets4 ,for it was no real law1 it had no scientific foundation1 and its conformity to the facts of the relative distances of the planets was only one of those very interesting and singular coincidences that startle one for the moment into thinking that there is some scientific significance in them4 ,another example of such a coincidence is in the fact that the mass of any given planet exceeds the total mass of all the planets of any less mass than itself4 ,in less than half a century after the discovery of the first planetoid1 ,neptune was discovered at a distance not at all corresponding to that indicated by ,bode's law4 ,it was not nearly far enough away1 and yet1 strangely enough1 it was by taking ,bode's law into consideration that the position was indicated which finally led to the discovery of the planet4 ,so while ,bode's law has been found to be no law at all1 it is1 nevertheless1 entitled to some mention because of its having thus stimulated research that has had such important results4 ,no really satisfactory and final explanation of the present state of the planetoids has ever been given4 ,at one time it was suggested that another planet had originally existed in the space between ,mars and ,jupiter1 and through some catastrophe had been shattered into the small bodies that now occupy that space4 ,but this has been shown to be impossible4 ,it is now thought probable that in the original nebula the matter forming the planetoids might have been prevented from condensing into a planet by the powerful gravitative influence of ,jupiter4 ,this influence1 however1 was not sufficiently strong to bring them entirely under his control4 ,even yet he pulls some of them five or six degrees out of the path they otherwise would take when they venture within the limits of his domain2 but he does not capture them1 so they have been left to circle around the sun as mere fragments of bodies1 with no force to combine and make a world1 no mass to hold an atmosphere1 and with nothing to prevent them from quickly condensing and from radiating all their heat into space4 ,they are1 in the main1 just cold1 dark1 lifeless rocks and lumps of matter whirling through space in a maze of interlacing orbits1 some of them almost as far from the sun as ,jupiter and some almost as near as ,mars--one1 indeed1 a little nearer than ,mars at certain times--but most of them swarming more thickly about half-way between ,mars and ,jupiter1 not far from the place that ,bode's law assigned to a planet4 ,after the first planetoid was discovered and had been observed for a few weeks1 it was lost and had to be rediscovered by means of mathematical computation of its orbit4 ,where this computation showed that it ought to be1 there it was found1 on the very last day of the same year1 #ahja4 ,early the next year another body of the same sort was discovered1 two years later another was found1 and still three years later a fourth came into view4 ,these four were the only ones known in this branch of the solar family for nearly forty years thereafter4 ,in #ahde another period of discovery commenced1 and has ever since continued1 until there are now between six and seven hundred of these little bodies that have disclosed their right to be known as members of the sun's family4 ,it is probable that there may be still many more of them1 since a new one comes to light every now and then on a photographic plate1 and there is no indication of any limit to the number that may thus appear4 ,it is likely that about all have been discovered that can be seen even with a telescope1 for a fairly systematic and thorough search has been made of the heavens for this purpose during the last half-century4 ,this work has resulted in a continually decreasing number of discoveries1 until this method of search has finally been practically abandoned4 ,but it not infrequently happens that in photographing the stars a little trail of light is discovered on the plate1 showing that some heavenly body with sensible motion has been caught on it4 ,and this usually proves to be a new planetoid4 ,no matter how long a photographic plate is exposed1 the fixed stars imprint themselves on it only as points of light4 ,when the impression is a little streak of light instead of a dot1 the object is shown to be in motion1 and is either a planetoid1 a satellite1 or a comet4 ,the fixed stars would make a trail also if the photographic apparatus were not regulated by clockwork1 so as to follow the star in its apparent daily motion across the skies4 ,the planets and other bodies in the solar system are sufficiently near to have a sensible motion in addition to the motion caused by the rotation of the earth1 which is the only motion we have to take into account in dealing with the aspects of the stars4 ,the first planetoid discovered was called ,ceres1 the next one ,pallas1 the third ,juno1 and the fourth ,vesta4 ,this pretty custom of naming them after the gods and goddesses of mythology was continued1 with some variations1 until perhaps three hundred had been so christened4 ,but the number of them became too prodigious2 and when so many began to swarm into view1 waiting to be named1 the utilitarian method of designating them simply by numbers in the order of their discovery was adopted4 ,the only distinguishing feature of so numbering them is that each number is placed in a little circle4 ,thus ,ceres is 1 ,pallas 1 and so on4 ,those of them that have any special claim to distinction1 however1 are still referred to by their own names1 if they have any1 in spite of this most orderly attempt to make them fit for easy reference in a list4 ,there are so many of the planetoids1 and they are so minute1 that even after they have been discovered they are frequently lost again4 ,hence it is sometimes uncertain when they register themselves on the photographic plates whether they are really new to us or have been known before4 ,in such cases they are named temporarily after the letters of the alphabet1 and1 when the alphabet is exhausted1 a second letter is added4 ,thus ,a to ,z1 then ,,ab to ,,az1 ,,bc to ,,bz1 and so on in a sort of 8round40 ,sometimes these combinations of letters become the fixed designation of a planetoid1 as a nickname sometimes clings to a person4 ,and thus it happens that we sometimes read of one in particular of these little bodies that is conspicuous for the great eccentricity of its orbit1 called 8,,wd40 ,the letters are not its initials1 but its nickname4 ,it really has no name other than its number in the list2 but it became famous while it was temporarily designated as 8,,wd10 and thus it continues to be called4 ,the aid of a telescope is necessary in order to see the planetoids1 though it is said that ,vesta1 under very favorable conditions1 sometimes comes within the limit of visibility4 ,she is the brightest of them all1 though not the largest1 and her brilliancy is the subject of much interesting speculation among astronomers1 who have not yet been able to account for it4 ,she seems from her excessive brightness to be covered with clouds2 and yet it is manifestly impossible that so small a body could have held an atmosphere throughout these long ages1 though clouds presuppose an atmosphere4 ,no doubt1 in time this mystery of ,vesta's brilliancy will be made plain4 ,bright as she is in proportion to her size1 and even if she sometimes can be seen1 one cannot reasonably expect anything very brilliant to our view from a body not much more than a hundred miles in diameter1 shining by reflected light1 nearly two hundred million miles away4 ,ceres1 as far as we yet know1 is the largest of the planetoids1 and may be something more than four hundred miles in diameter4 ,juno is somewhere near the same size4 ,pallas is about two hundred miles in diameter1 and ,vesta about one hundred and eighteen4 ,no doubt1 these four were the first to be discovered1 because they are the largest and so the easiest to be seen4 ,at any rate1 no others yet seen exceed them in size1 and some of the more lately discovered are not more than fifteen or twenty miles in diameter4 ,many of those discovered by photography are doubtless even smaller than these1 and are1 perhaps1 mere meteors in size4 ,the combined mass of all those discovered up to this time is far smaller than that of any of the large planets1 or even than that of our moon4 ,their mass cannot1 of course1 really be measured1 because they are too small to have any perceptible gravitative effect on other bodies1 and mass can only be determined by the influence of one body on another4 ,but we do know that their aggregate mass1 if it exceeded a certain limit1 would show some disturbing effect on ,mars2 and1 since it does not do this1 we know that all of them taken together would make an extremely insignificant body4 ,while the planetoids all revolve around the sun in the same manner and in the same direction as the planets do1 yet they are very erratic in their courses1 and do not all keep within the narrow limits of the zodiac through which--happily for our convenient observation--the larger bodies travel4 ,the orbits of many of them are extremely elliptical1 while some are almost circles2 and their inclination to the ecliptic varies from almost nothing to nearly fifty degrees4 ,if one could catch from one side a view of them all together1 they would have much the appearance in space of a flock of swallows1 the individuals darting this way and that1 passing above and below one another in such intricate sweeps and sinuosities that it would be impossible to keep track of them separately4 ,and yet time has brought these apparently tangled orbits into such nice adjustment that the little bodies can continue to cross and recross each other's paths with no danger of interference from each other4 ,such collisions as there may have been occurred in the very beginning of their careers4 ,such of them as came into collision then traveled on together as one body until accommodation was made for all4 ,one of the most wide-wandering of these tiny bodies has been named ,eros1 after the little god of love1 more commonly known as ,cupid4 ,it has a particular interest for us1 because of all the heavenly bodies it at times comes nearer to us than any except the moon and an occasional comet4 ,at its nearest it is within fourteen million miles of the earth1 which is more than ten million miles nearer than the closest approach of ,venus1 the nearest of the large planets4 ,this little body was thus near us in #ahid2 but we did not then know this1 for ,eros was not discovered until #ahih4 ,after its discovery1 however1 it was traced back on many photographic plates1 and the fact that it had been in our neighborhood was learned4 ,for untold ages it has been making these visits to us every thirty-seven years1 and we have known nothing of them4 ,its next near approach will be in #aica1 and it will continue to come thereafter every thirty-seven years4 ,now that we know about them1 these visits are not only pleasant to contemplate1 but it is expected that when they occur the planetoid will be of great scientific value to us in helping to determine more surely and accurately the exact distance of the sun4 ,the planetoids1 though so minute and of no value as a spectacle1 have been1 and still are1 very useful little bodies to us in a scientific way4 ,in addition to furnishing an easy means of measuring the distance of the sun1 they promise to throw some light on various questions of physics in which the planets1 too1 are involved4 ,the brilliancy of ,vesta1 for instance1 which has been mentioned1 and the unaccountable variability in the brightness of some others of them have yet to be adjusted to known physical laws4 ,even the extreme eccentricity of some of their orbits1 and the large tilt of some of them to the ecliptic1 may be suggestive in finally solving certain planetary problems1 for these impish little bodies are far from conforming to the regular ways of the planets1 and there is1 of course1 some mechanical reason for their apparent waywardness4 ,,xviii ,,conclusion ,the great variety of beauty that the planets present to us is sufficient to keep us always interested in them1 when once we have acquired an acquaintance with them4 ,rarely is there an evening when some one of them does not enhance the charm of the splendid spectacle of the sky in which all the heavenly bodies save the sun have a part4 ,their greater brilliancy often brings them into view before the stars have begun to glow in the evening1 and prolongs our sight of them after the rays of the sun have blotted out the light of the stars in the morning4 ,thus they are always single in their loveliness1 and always hold a distinguished place in the midst of the brilliant company of the stars4 ,having considered these brilliant bodies individually and in detail1 as we have1 we ought by this time to be able to identify any one of them that shows itself in the evening sky1 and to have a pretty fair notion of the general character and peculiarities of each4 ,but even if one does not much care for detailed information concerning them1 or1 before seeking that1 prefers first to become familiar with their appearance1 a quick and sure recognition of them may be had by noting their positions and their very striking individual aspects as set forth in the preceding chapters4 ,on seeing a bright object in the sky that does not seem to be a familiar star1 simply stop and look at it4 ,does it twinkle8 ,if it does not1 it is a planet4 ,if it is more than forty-five degrees from the sun1 or if it is seen at a time when the sun has been down more than three hours1 then it is neither ,mercury nor ,venus1 and must be either ,mars1 ,jupiter1 or ,saturn4 ,is it very bright and pinkish in tone8 ,then it is ,jupiter4 ,is it very bright and quite red8 ,it is ,mars1 not far from opposition4 ,is it not very bright1 but small and rosy8 ,then it is ,mars going toward conjunction4 ,is it yellow in tone and1 while large and conspicuous1 still not so very brilliant8 ,it is ,saturn4 ,if the planet we seek to name is nearer to the sun than forty-five degrees1 but is still well above the horizon1 it may be either of these three--,mars1 ,jupiter1 ,saturn--or it is ,venus4 ,if it is very bright and silvery1 it is certainly ,venus4 ,if it is very low in the sky and very near the sun1 it may be any one of the five visible planets4 ,in such a position ,mars will always be very small1 and the others always larger than a first-magnitude star2 and they may all twinkle a little--,mercury almost as much as a star4 ,their size will show them all 7except ,mars7 as planets1 but it will be somewhat more difficult to tell which is which than it is when they are higher up in the sky4 ,the best thing to do in such circumstances is to look up their positions either in this book or in an almanac4 ,the almanac will serve as a footman to announce them4 ,the book1 it is hoped1 has so recorded their peculiarities and habits that either their appearance or their place will be sufficient to make them known4 ,in any event1 the problem of identification in this position will not keep one long1 for in a situation presenting these greater difficulties the planet will be visible for less than an hour after sundown4 ,besides1 it is not likely at such times to attract one's involuntary attention1 but when under observation in such a situation is usually sought out by those already somewhat informed as to the planet's habits and appearance1 which will betray its identity4 ,it is information of this sort that ,i have endeavored to give in these pages1 and it is hoped that the reading of them will be the beginning of a long and intimate acquaintance with these charming and always interesting individuals4 ,individuals the planets inevitably become to any one who learns to know them during the long1 quiet nights in the country1 or wherever an opportunity is afforded really to contemplate their peculiar traits and features4 ,like individuals of whatever kind1 they impress different persons in different ways4 ,as ,i have watched them from year to year ,i have come to have a very distinct impression of ,jupiter as slow and majestic1 and yet not lacking in joviality2 ,saturn as friendly1 but reserved2 ,mars as sturdily brisk and busy2 ,venus as always gracious and smiling2 and ,mercury as irresponsible and roguish4 ,others might have an entirely different feeling in regard to them2 but an intimate acquaintance with them1 which is not wholly scientific1 cannot fail to stamp them as in some sort individuals4 ,and when we consider that these interesting individuals are closely related members of our cosmic family1 their ever-changing beauty of aspect1 the history of their development and their affairs generally1 gain a significance to us that no other heavenly bodies can have4 ,the two groups of planets--the inner and the outer--are like two sets of children in a family3 born of the same parent1 but under very different circumstances1 and in very different surroundings4 ,mars1 the earth1 ,venus1 and ,mercury are all1 as compared with the outer planets1 small and dense1 with more or less thin atmospheres and an abundance of heat and light4 ,they all lie comparatively near to the sun1 and are composed of the denser material lying near the center of the great nebula1 which was the original form of the entire solar system4 ,probably denser to begin with than the others1 they have1 on account of their diminutive size1 developed more rapidly and are further advanced toward the final state of solidity which we shall all attain in the end4 ,mercury1 the smallest1 is already old and seamed and hardened4 ,mars1 the next in size1 is well advanced1 but still has an atmosphere and some other signs of vitality4 ,venus1 though we know so little about her1 has probably a long period of development yet before her2 while this warm1 nourishing earth1 which seems to us the best one of them all1 will probably for a still longer time than ,venus hold its atmosphere and remain green and flourishing4 ,on the other side of the vast space which divides the two groups of the sun's family dwell ,jupiter1 ,saturn1 ,uranus1 and ,neptune4 ,they are all tremendous in volume1 enveloped in immense atmospheres1 far1 far from our common source of heat and light1 of comparatively slight density1 and probably formed from the lighter material composing the outer edges of the parent nebula1 and1 because of their immense size1 still in a very early stage of development4 ,the two groups could scarcely seem more widely different if they belonged to different systems2 but the members of each are all closely akin1 and each one in its own way1 determined by its size and environment1 is developing toward the same end4 ,if there is life on any of these outer planets1 it must be of a sort of which we have no conception4 ,jupiter and ,saturn are probably red-hot1 and could sustain nothing more cold-blooded than a race of salamanders1 though why a race of intelligent salamanders should or should not exist there1 is a question that one might make bold to answer according to one's fancy4 ,uranus and ,neptune are smaller1 and perhaps less hot than ,jupiter and ,saturn2 but we really know very little about the state of their domestic affairs1 and the little we do know in no way indicates a place of abode for any sort of intelligence conceivable to us4 ,we can1 however1 conceive of a time in the far-distant ages when these four hot and vaporous planets may have become sufficiently condensed to have a solid crust1 and yet have sufficient internal heat to moderate the frigid temperature that would be normal at their distance from the sun1 and they might then support life even somewhat resembling and perhaps even more gloriously beautiful than that with which we are familiar4 ,of the existence of life somewhat similar to ours on the smaller1 near-by planets we may have something nearer a reasonable conception1 though we are nowhere near the possession of any real knowledge concerning it4 ,mercury1 we have every reason to think1 cannot support life1 mainly because of his lack of atmosphere2 but also because of his long rotation1 which affords no alternations of day and night1 but leaves him with one side always burning-hot and the other inconceivably cold4 ,venus might very well have a climate not utterly unlike ours1 and hence be habitable for beings somewhat resembling us1 if she has1 as she has long been thought to have1 a heavier atmosphere than the earth has1 and if she has alternations of day and night4 ,but we have seen that1 owing to the obscurity of the surface of ,venus1 our knowledge in regard to these conditions is far from certain1 and we have little reason to have even speculative ideas concerning life there4 ,with ,mars it is a more open question4 ,we can see that planet1 and see it fairly well4 ,it has an atmosphere and changes of seasons1 and while it may not afford a climate that would be exactly attractive to us as a place of transmigration1 it is not particularly unreasonable to let our fancy play over the rather pleasant speculation concerning the presence there of beings at least understandable by us1 even if not wholly congenial4 ,whatever each planet affords in the way of life and human interests1 all of them must ever be to us the most interesting things in all nature1 outside of our own earth1 in the two regards already pointed out3 first1 as the most beautiful objects of vision among all the starry hosts1 and1 second1 as our nearest kindred in this universe of suns and systems of worlds4 ,together the earth and they circle ceaselessly around and around the sun1 following in nicely adjusted orbits that great luminary as it sweeps majestically on through space toward the beautiful ,vega1 itself a sun1 and1 so far as we now know1 in this close companionship we shall continue until every planet and the sun itself has become cold and dark and lifeless4 ,and then1 perhaps1 or even before the light of our system is finally extinguished1 we may meet another wandering sun1 and in the marriage of the two great bodies another system of worlds may be evolved of which we and the planets shall form a part4 ,,symbols ,,used ,,in ,,almanacs ,mercury4 ,new ,moon4 ,venus4 ,first ,quarter4 ,earth4 ,full ,moon4 ,mars4 ,last ,quarter4 ,jupiter4 ,sun4 ,saturn4 ,conjunction with the sun2 or1 in the case or ,uranus4 of two planets or a planet and the moon1 ,neptune4 near together4 ,opposition4 ,quadrature4 ,examples3 ,mars and ,venus near together4 ,jupiter in opposition4 ,jupiter in conjunction4 ,inf4 ,mercury in inferior conjunction4 ,sup4 ,mercury in superior conjunction4 ,venus and ,moon near together4 ,,index ,adams1 #bcf-bch4 ,alcor1 star in ,great ,dipper1 #aje1 #bcf4 ,aldebaran1 first-magnitude star1 #gi-hj1 #aec1 #ahh1 #baj4 ,antares1 star in ,scorpio1 #hf1 #aec1 #afj1 #ahg1 #ahi1 #bji1 #bab4 ,aquarius1 constellation of the zodiac1 #gf1 #hh-hi1 #ia-ib1 #ahg1 #bab-bac1 #bba1 #bdb4 ,arcturus1 #bd1 #hd2 color of1 #ajb4 ,ariel1 satellite of ,uranus1 #bcb-bcc4 ,aries1 constellation of the zodiac1 #gf-gh1 #ij-ib1 #bab1 #bdb4 ,asteroids1 #bdd-beg4 ,bee-hive1 #hb1 #baa-bab4 ,bode's law1 #bde-bdi4 ,botes1 star of first magnitude1 #ajb4 ,callisto1 satellite of ,jupiter1 #bjj1 #bje4 ,cancer1 constellation of zodiac1 #gf1 #hb1 #ia-ib1 #ahh1 #baa-bab4 ,capella1 star of first magnitude1 #aia4 ,capricornus1 one of the twelve constellations of the zodiac1 #gf1 #hh-hi1 #ia-ib1 #ahg1 #bab1 #bbi4 ,cassiopeia1 constellation1 #gg4 ,castor and ,pollux1 #ha1 #ahh1 #baa1 #bdb-bdc4 ,ceres1 first planetoid discovered1 #bea1 #bec4 ,constellations of the zodiac1 #ge-ib4 ,deimos1 satellite of ,mars1 #ahj-aha4 ,dione1 satellite of ,saturn1 #bbb4 ,earth1 relation to planets1 #aa-ae1 #ai2 nearness to sun1 #ai2 terrestrial planet1 #da2 movement of1 #ea2 position in regard to ,mercury1 #abj-aba2 likeness to ,venus1 #ach-adj4 ,enceladus1 satellite of ,saturn1 #bbb4 ,encke's comet1 #aji4 ,equinox1 derivation of word1 #gd4 ,eros1 small planet1 #bee-bef4 ,europa1 satellite of ,jupiter1 #bjj-bja4 ,flagstaff1 ,arizona1 observatory of1 #age-agf4 ,fomalhaut1 #ahg1 #bji1 #bac4 ,galileo1 #acf4 ,ganymede1 satellite of ,jupiter1 #bjj-bja1 #bje4 ,gemini1 constellation of the zodiac1 #gf1 #ha-hb1 #ia-ib1 #ahh1 #baj-baa1 #bac4 ,george ,,iii41 ,uranus first called ,georgium ,sidus after1 #bbf4 ,great ,dipper1 #gc1 #gg1 #hd1 #if1 #ajd1 #aje1 #ahf1 #bcf4 ,hamal1 star in constellation of ,aries1 #gh4 ,herschel1 discovery of ,uranus by1 #bbf-bbg1 #bcb4 ,hyades1 the1 #gi4 ,hyperion1 satellite of ,saturn1 #bbb4 ,inferior planets1 #dj4 ,io1 satellite of ,jupiter1 #bjj1 #bja4 ,japetus1 satellite of ,saturn1 #bbb4 ,juno1 planetoid1 #bea1 #bec4 ,jupiter1 color1 #e2 attraction between ,saturn and1 #ae2 distance from sun1 #ai2 size and importance of1 #bj2 movement1 #be1 #fe2 satellites1 #cd1 #ajf1 #aii-bje2 long known1 #ch2 superior planet1 #da2 space between ,mars and1 #db2 influence on comets1 #dd2 gibbous1 #ff2 distance from ecliptic1 #gb2 near ,antares1 #hf2 in ,scorpio1 #abg2 size and velocity1 #ahc-ahe2 place in sky1 #ahf-aij2 distance1 light1 and heat1 #aij-aic2 seasons and atmosphere1 #aic-aie2 surface features1 #aie-aii2 symbol1 #bje2 compared to ,saturn1 #bac-bad1 #bae-bah2 nearness of asteroids to1 #bdd2 how to recognize1 #bei-bfd4 ,laplace1 nebul hypothesis of1 #bh1 #cj4 ,leo1 constellation of zodiac1 #gf1 #hb-hc1 #ia-ib1 #ahh1 #baa-bab1 #bba4 ,leverrier1 discovery of ,neptune by1 #bcf-bch4 ,libra1 constellation of zodiac1 #gf1 #he1 #ia-ib1 #ahh1 #bab4 ,little ,dipper of the ,pleiades1 #gi4 ,lyre1 constellation of the1 #ed4 ,major planets1 #ai4 ,mars1 8eye0 of1 #ab2 distance from sun1 #ai2 nearness to earth1 #bj2 movement of1 #be1 #fe2 long known1 #ch2 superior planet1 #da2 space between ,jupiter and1 #db2 speed1 #ea2 gibbous1 #ff2 distance from ecliptic1 #gb2 color1 #hj1 #hf1 #bei2 position in regard to ,antares1 #hg2 density1 #aaj2 nearness to ,venus1 #abh2 variety in brightness1 #aea-aeb2 how and where to identify1 #aeb-afb1 #bei-bfe2 size1 atmosphere1 and temperature1 #afb-afe2 distance and brilliancy1 #aff-agj2 seasons1 #agj-aga2 surface aspect1 #agb-agi2 satellites1 #ahj-aha2 symbol of1 #ahb2 nearness of asteroids to1 #bdd2 ,bode's law and1 #bde-bdf1 #bdh-bdi2 smallness1 #bfj4 ,mercury1 #ah2 nearest planet1 #ai2 unfavorable situation for observation1 #bj2 easily recognized1 #bb2 age of1 #cd2 dense matter of1 #cg2 long known1 #ch2 inferior planet1 #dj2 terrestrial planet1 #da2 irregularities of1 #dd-de2 number of revolutions1 #dg2 orbit1 #dh2 apparent motions1 #eg-eh2 transits1 #fa2 distance from ecliptic1 #gb-gc2 color1 #hj1 #hf2 in ,scorpio1 #hg2 elusiveness of1 #ic-ie2 how to find1 #if-ajj1 #bei2 distance and brightness of1 #aja-aje2 size1 #ajf-aaj2 relation to sun1 #aaa-aah2 transits1 #aai-aba2 lack of atmosphere1 #add1 #adf2 resemblance to ,mars1 #aec2 ,bode's law and1 #bde4 ,milky ,way1 #hg1 #hh1 #hi4 ,mimas1 satellite of ,saturn1 #bbb4 ,minor planets1 #ai4 ,mizar1 star in ,great ,dipper1 #aje1 #bcf4 ,moon1 #bc2 once called planet1 #ci2 distance from ecliptic1 #gc4 ,moulton1 ,professor1 #agh4 ,neptune1 discovery1 #ae2 distance from sun1 #ai1 #dc2 not visible to naked eye1 #bj2 age1 #cd2 diffuse matter of1 #cg2 unknown to ancients1 #dj2 superior planet1 #da2 influence on comets1 #dd2 one revolution1 #dg2 orbit1 #dh2 movement of1 #fe2 distance from earth1 #bcd2 discovery1 #bce-bcg1 #bdg2 symbol1 #bch2 atmosphere1 #bci-bdj2 satellite1 #bda2 motion1 #bdb2 brightness1 #bdc4 ,oberon1 satellite of ,uranus1 #bcb-bcc4 ,orion1 #abc4 ,pallas1 planetoid1 #bea4 ,phecda1 star in ,great ,dipper1 #ajd4 ,phobos1 satellite of ,mars1 #ahj-aha1 #bjb4 ,phbe1 satellite of ,saturn1 #bbb-bbc4 ,pisces1 constellation in zodiac1 #gf-gg1 #ij-ib1 #afj1 #ahg1 #bab1 #bdb4 ,pleiades1 #gi-hj1 #aec1 #ahh1 #baj4 ,prsepe1 or the ,bee-hive1 #hb1 #baa-bab4 ,regulus1 star in the constellation of ,leo1 #hc-hd1 #ahh1 #bab4 ,rhea1 satellite of ,saturn1 #bbb-bbc4 ,sagittarius1 constellation of zodiac1 #gf1 #hg-hh1 #ia-ib1 #ahf1 #ahi1 #bji1 #bab1 #bbi4 ,saturn1 rings and moons of1 #ab1 #bah-bbc2 distance from sun1 #ac1 #ai2 attraction between ,jupiter and1 #ae1 #ahe2 size and importance1 #bj2 object-lesson from1 #bi2 long known1 #ch2 superior and outer planet1 #da-db2 influence on comets1 #dd2 length of year on1 #dg2 movement1 #fe2 distance from ecliptic1 #gb2 satellites1 #ajf2 color1 #bjf1 #bji1 #bei2 as evening star1 #bjg2 slight motion1 #bjh2 circuit of skies1 #bji-bac2 size and distance1 #bac-bae2 surface aspects1 #bae-baf2 day and night1 #bag-bah2 seasons1 #bbd2 symbol1 #bbd2 ,bode's law and1 #bde-bdf2 how to recognize1 #bfj-bfd4 ,schiaparelli1 #agd-age4 ,scorpio1 constellation of zodiac1 #gf1 #he-hh1 #ia-ib1 #abg1 #aec1 #ahf1 #ahh1 #bab-bac4 ,sidereal year1 #di-ej4 ,sirius1 the dog-star1 #abc4 ,spica1 #hd-he1 #ahh4 ,sun1 controls planets1 #ad1 #ag2 distance from earth1 #ah2 center of planet system1 #bg2 probable formation of1 #cf2 once called planet1 #ci2 situation in orbit1 #eb2 vernal equinox1 #gf2 relation to ,mercury1 #aaa-aah2 relation to ,mars1 #aff-afg2 relation to ,jupiter1 #ahc-ahe4 ,superior planets1 #da1 #fe-gj4 ,symbols in almanacs1 #bfg4 ,synodic year1 #ej1 #eb4 ,taurus1 constellation in zodiac1 #gf1 #gi-hj1 #ij-ib1 #ahh1 #baj1 #bab1 #bdb4 ,tethys1 satellite of ,saturn1 #bbb4 ,themis1 satellite of ,saturn1 #bbb-bbc4 ,titan1 satellite of ,saturn1 #bbb-bbc4 ,titania1 satellite of ,uranus1 #bcb4 ,triangulum1 #gh4 ,umbriel1 satellite of ,uranus1 #bcb-bcc4 ,uranus1 gravitational influence on1 #ae2 distance from sun1 #ai1 #bbi-bcj2 unknown to ancients1 #dj2 superior planet1 #da2 influence on ,neptune1 #dc2 influence on comets1 #dd2 movement1 #fe2 nearness to ecliptic1 #gb2 discovery1 #bbe-bbf1 #bdf2 symbol1 #bbg2 time of revolution1 #bbh2 size1 #bca2 satellites1 #bcb-bcc2 irregularity of1 #bcf4 ,vega1 in constellation of the ,lyre1 #ed1 #aia1 #bff4 ,venus1 the planet1 #b1 #d1 #e2 nearness to sun1 #ai2 nearness to earth1 #bj1 #bef2 movement of1 #be2 long known1 #ch2 early names of1 #ci2 inferior planet1 #dj2 terrestrial planet1 #da2 brightest planet1 #db2 apparent motions1 #eg-eh2 transits1 #fa2 distance from ecliptic1 #gb2 seen from ,mercury1 #aje2 density1 #aaj2 beauty1 #abb2 how and when to see1 #abc-aca2 distance and brightness1 #acb-acg2 likeness to earth1 #ach-adj2 atmosphere and seasons1 #ada-adg2 transits1 #adg-adi2 sign of1 #aej2 ,bode's law and1 #bde2 how to know1 #bei-bfd4 ,vesta1 planetoid1 #bea1 #bec1 #bed1 #beg4 ,virgo1 constellation of the zodiac1 #gf1 #hd-he1 #ahh1 #bab4 ,zodiac1 the1 #ga-ib4 ,,the ,,end