,,lincoln ,,lapaz ,,and ,,jean ,,lapaz ,,space ,,nomads ,,meteorites ,,in ,,sky1 ,,field1 ,,laboratory ,,holiday ,,house1 ,,new ,,york ,,copyright1 #aifa1 ,,by ,,lincoln ,la,p,a,z ,,jean ,la,p,a,z ,,printed ,,in ,,the ,u4,s4,a4 ,illustration3 ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,fireball speeding across field of camera during the photographing of the ,great ,spiral ,nebula in ,andromeda1 by ,josef ,klepesta1 at the ,prague ,observatory1 ,czechoslovakia1 ,september #ab1 #aibc4 ,,preface ,meteoritics is the study of the only tangible entities that reach us from outer space4 ,except for the meteorites1 scientists have to depend entirely on studies of some form of radiation for all their knowledge of the wider cosmos lying outside of the atmosphere of the earth4 ,and none of the radiations reaching us from various sources afar can be held in the hand for examination4 ,each type of radiant energy incident upon our earth--whether that energy be light from the sun or from the more distant stars or the galaxies1 or the reflected light from the planets and moons of our ,solar ,system1 or the less familiar forms of radiation1 such as radio waves and cosmic rays--must be measured and permanently recorded by complicated instruments4 ,often the results given by even the most sensitive and tractable of these scientific robots turn out to be exceedingly difficult for man1 their master1 to interpret4 ,but the meteorites require no such temperamental instruments for their measurement4 ,they are themselves a permanent record4 ,they can be weighed1 sectioned1 and polished4 ,they can be studied chemically1 microscopically1 and radiometrically4 ,in fact1 they can be investigated directly1 just as they are themselves1 in our hands1 by any method modern science may be clever enough to devise4 ,this is why1 now with the world's attention drawn to ambitious plans for the exploration of the cosmos1 meteors and meteorites are of increasing interest and importance4 ,we have planned and written this book to be a sound and yet largely nontechnical introduction to the science of meteoritics4 ,our daily experiences in the ,institute of ,meteoritics have afforded us a fortunate advantage in making such a presentation4 ,for1 in addition to our work in the field1 laboratory1 and classrooms1 we have frequently conducted young people through the museum and workrooms of the ,institute and so have had the opportunity of learning their point of view at the same time they were venturing into ours4 ,we hope our book will instill in the reader an abiding interest in the location and protection1 the recovery and preservation and especially in the study of those cosmic missiles of iron1 iron-stone1 or stony composition that represent mankind's only ponderable links with the vast universe lying beyond the limits of the earth's atmosphere4 ,although all photographs and special depictions not made by our staff are individually credited1 we wish to express our personal thanks for the privilege of reprinting them here4 ,all photographs that are without a credit line have been made by members of our staff4 ,lincoln ,la,paz ,jean ,la,paz,university of ,new ,mexico1 ,albuquerque1 ,march #bj1 #aifa ,,table ,,of ,,contents ,,preface #e #a4 ,a ,,meteorite ,,falls ,,in ,,the ,,taiga1 ,u4,s4,s4,r4 #aa #b4 ,a ,,meteorite ,,falls ,,in ,,the ,,wheatland1 ,u4,s4,a4 #bc #c4 ,,found ,,and ,,lost ,,giants #cf #d4 ,,when ,,is ,a ,,crater ,a ,,meteorite ,,crater8 #db #e4 ,,heaven ,,knows ,,where ,,or ,,when #ff #f4 ,,finders ,,foolish1 ,,finders ,,wise #ge #g4 ,,landmarks1 ,,skymarks1 ,,detectors #hd #h4 ,,the ,,nature ,,of ,,meteors #aja #i4 ,,the ,,nature ,,of ,,meteorites #aah #aj4 ,,tektites1 ,,impactites1 8,,fossil0 ,,meteorites #acd #aa4 ,,omens ,,and ,,fantasies #adg #ab4 ,,the ,,modern ,,view #aeh #ac4 ,,present ,,and ,,future ,,applications #aff ,,for ,,further ,,reading #agg ,,index #aha ,,space ,,nomads ,,meteorites ,,in ,,sky1 ,,field1 ,,laboratory ,illustration3 ,painting of the ,ussuri fireball by the ,iman artist1 ,p4 ,i4 ,medvedev4 #a4 ,a ,,meteorite ,,falls ,,in ,,the ,,taiga1 ,u4,s4,s4,r4 ,the morning of ,february #ab1 #aidg1 dawned cold but bright and sunny in the wide ,ussuri valley of ,eastern ,siberia4 ,during the early morning hours the people in the villages went about their everyday chores as usual4 ,farmers fed and watered their livestock1 while housewives tidied rooms and fired up stoves for heating and baking4 ,miners went to work deep underground4 ,an artist seated himself outdoors near his home to make exercise sketches4 ,in a densely wooded area on the slopes of a nearby mountain range1 a logging crew began a day's timber-cutting4 ,suddenly1 at #aj3ce a4m41 an extraordinarily large and brilliant fireball flashed above the central part of the mountain range4 ,it streaked across the sky in less than #e seconds and disappeared beyond the western foothills of the range4 ,then the inhabitants of a wide area heard what seemed to them a mighty thunderclap followed by a powerful roar like an artillery cannonade4 ,many people felt a strong airwave4 7,field parties later found that those who noticed this effect were quite close to the place where the meteorite fell47 ,for several hours afterward1 a large black column of smoke tinged with a reddish-rose color stood above the place of fall4 ,gradually1 this cloud spread outward1 became curved and then zigzag in form1 and finally vanished toward the end of the day4 ,the flash of the fireball and the loud noises that followed it caused panic among the farm animals4 ,cows lowed mournfully and herds of goats scattered in every direction1 chickens and other fowl squawked in alarm1 and dogs ran whining for shelter or crouched against the legs of their masters4 ,in the villages1 the airwave blew snow off the roofs of houses and other buildings1 while the strong earth-shocks opened windows and made doors swing ajar4 ,housewives were dismayed to see glass windowpanes shattered in their frames and burning coals and firebrands jolted out of the wood-burning stoves4 ,even deep in the mineshaft1 the vibrations in the air were strong enough to snuff out the miners' lamps1 leaving the men in darkness4 ,on seeing the huge fireball streak across the sky1 the artist put aside his practice sketch and began a picture of the display before his impressions of it could fade4 ,his painting of this natural event is now famous4 ,not only is it on display in scientific museums all around the world1 but a color reproduction of it has been issued in ,russia as a postage stamp4 ,the forester supervising the logging crew reported that his attention was first attracted to the sky when he noticed a strange 8second0 shadow rotating rapidly about the tree that cast it4 ,on looking up1 he saw a blindingly bright fireball1 twice as large as the sun1 a fiery globe that threw off multicolored sparks as it passed4 ,not long after the fireball disappeared behind the trees1 the forester heard a loud noise like nearby cannonading and saw a large dark-colored cloud--later tinged with red--billow up over the impact point4 7,the members of the logging crew were among the very few persons actually abroad near the place of fall4 ,it turned out that they were only about #i miles from it47 ,as soon as the many eyewitnesses of the fireball had recovered from their fright1 the questions almost everyone asked were 8,what could it have been80 and 8,where did it come down80 ,to answer the first question was not as difficult as to answer the second4 ,local scientists in ,vladivostok and ,khabarovsk1 the nearest cities of some size1 suspected from the first that a very large meteorite fall had occurred4 ,but exactly where8 ,all they could be certain of was that the impact point lay in the ,ussuri taiga1 a formidable wilderness4 ,the ,sikhote-,alin mountains lie along the ,siberian coast between the ,sea of ,japan and the ,tatar ,strait4 ,the ,ussuri taiga is a vast1 low-lying1 marshy1 densely forested region fronting the western flanks of these mountains4 ,ordinary cedars1 pines1 oaks1 and aspen grow in the taiga1 but the region is also noted for such rare plants and trees as the celebrated ginseng1 the cork tree1 the ,greek nut tree1 and the black birch4 ,wild grape and ivy vines intertwine the upper branches of the thick forest1 and the trunks of the trees themselves rise from an almost impenetrable maze of brush and downed timber4 ,so dense is the forest that in summer1 a man can see no more than #aj or #ab feet in any direction4 ,yet in winter1 the explorer's lot is no easier2 for1 although the deciduous trees then stand leafless1 the ground is covered by three feet or more of snow4 ,and in the early fall1 violent cloudbursts often flood the taiga1 making travel impossible4 ,such was the inhospitable region in which the ,ussuri1 or 7as it is now known in the ,u4,s4,s4,r47 ,sikhote-,alin meteorite1 had chanced to fall4 ,for any search parties traveling on the ground1 the likelihood that they could find the fallen meteorite in that wilderness would have been very small4 ,the impact point of the ,ussuri meteorite was discovered in the only way really practical3 from the air4 ,fortunately1 the center of impact lay almost directly below the airlane connecting the towns of ,iman and ,ulunga1 so that the devastation produced by the meteorite fall in the taiga was clearly visible to aviators following this active air route4 ,the accounts several fliers gave concerning the widespread cratering and destruction they had seen from the air in the impact area led to the organization of two separate ground-search parties1 one at ,khabarovsk1 the other at ,vladivostok4 ,the ,khabarovsk group1 made up of four members of the ,geological ,society1 flew to the village of ,kharkovo1 the inhabited point nearest the site of fall4 ,after a rough and dangerous landing on the small1 snow-covered airfield at ,kharkovo1 the geologists began their trek into the taiga on foot4 ,throughout the entire trip1 the men1 burdened with supplies and equipment1 waded through waist-deep snow and camped in the open despite the arctic cold4 ,at almost the same time1 a geologist from ,vladivostok set out from the railway line up the ,ussuri valley to track down the fallen meteorite4 ,his progress was even more difficult than that of the ,khabarovsk party4 ,in addition to following a much longer route1 he did not have the invaluable information that the first party had got from the aviators4 ,he had to make his way slowly from village to village1 questioning eyewitnesses as he went and gradually determining the probable end-point of the meteorite fall4 ,illustration3 ,,courtesy ,,of ,e4 ,l4 ,,krinov ,splintered and broken trees at the site of the ,ussuri fall4 ,the route followed by the ,vladivostok geologist lay through the heart of the trackless snow-covered taiga4 ,fortunately1 he had with him two hunters who were well acquainted with the rigors of travel through the taiga and knew how to live off the land4 ,they slept in hunters' huts or under overhanging trees1 drank melted snow water1 and ate fried quail4 ,but they had not gone far when they found that their footwear was completely useless for a trek through the wet1 snowy taiga1 because their felt hiking boots quickly soaked up water and became very heavy4 ,so they swathed their feet in warm dry grass over which they tied large pieces of untanned leather4 ,after that1 the walking was much easier4 ,they were able to cover the ground so rapidly that they reached ,kharkovo only a day after the ,khabarovsk geologists had landed there at the small airfield4 ,at ,kharkovo1 the three feasted on pork1 milk1 and honey4 ,then loading a few provisions on a borrowed horse1 they started out to overtake the ,khabarovsk party4 ,they made such good time that the two groups were able to join forces and to enter the impact area as one expedition1 on ,february #bd1 #aidg4 ,a scene of great desolation awaited them in the central region of the meteorite fall4 ,masses of crushed stone had been hurled hundreds of feet by the violent impact4 ,denuded1 uprooted trees lay about--some cut in two as neatly as if by a saw4 ,large cedars had been splintered where they stood or had been torn up by the roots and thrown some scores of yards4 ,illustration3 ,,courtesy ,,of ,e4 ,l4 ,,krinov ,workmen excavating one of the large craters formed by the impact of the ,ussuri meteorites4 ,most impressive of all1 though1 were the numerous meteorite craters ranging in size from small bowl-like features to a basin more than #bh yards across and over #f yards deep--a depression large enough to hold a two-story house4 ,the investigators recovered many fragments of the iron meteorite that had broken to pieces not far above the earth's surface and had peppered the area of fall with high-speed meteoritic 8shrapnel40 ,with their meteorite recoveries and photographs of the cratered area1 the members of this first expedition returned to their respective towns and began a campaign by letter and wire to interest the ,moscow office of the ,academy of ,sciences of the ,u4,s4,s4,r4 in making a full-scale investigation of the ,ussuri fall4 ,the officials of the ,academy decided at once to send a special scientific expedition to the site of the meteorite fall4 ,a member of this later and better-equipped expedition compared the ,ussuri crater field to a bombed-out area4 ,in fact1 some of the meteorite specimens were fragments that closely resembled pieces of shattered shell-casing4 ,the edges of these fragments were jagged and bent1 and their surfaces1 which often displayed a rainbow-colored sheen1 were grooved and scarred by impact against the hard rock underlying the region in which the crater field had been formed4 ,in rare instances1 the investigators noted spiral twisting of the fragments1 an indication of the unusually violent disruptive forces to which they had been subjected at impact4 ,the scientists found several instances in which fist-sized meteorite fragments had actually penetrated into or through standing tree trunks1 either becoming imbedded in the wood or driving a hole right through the trunk4 ,illustration3 ,,courtesy ,,of ,e4 ,l4 ,,krinov ,a nickel-iron meteorite from the ,ussuri fall imbedded in the trunk of a cedar tree4 ,many whole individual meteorites also were recovered4 ,these were almost always covered by a thin1 smooth 8glaze0 known as fusion crust4 ,this crust forms on the surface of a meteorite as it plunges rapidly through the air4 ,the heat generated during its flight causes the outer 8skin0 of the meteorite to melt4 ,later1 when the mass has cooled off1 the thin coating of melted material hardens1 forming a rind or crust4 ,by the beginning of #aiea1 the ,russians had sent three more expeditions to the site of the ,ussuri fall4 ,their scientists found1 in all1 #abb craters 7the largest more than #hj feet in diameter7 as well as numerous funnels resulting from the penetration of smaller meteorites into the earth4 ,by means of both visual and instrumental searches1 they also recovered #bj1jjj meteoritic fragments and individual meteorites4 ,the smallest ,ussuri specimens weighed no more than the thousandth part of a gram4 7,there are #dec4ei grams in a pound47 ,some of these tiny masses were found lying cupped in leaves4 ,the largest individual meteorite recovered weighed about #c1hci pounds4 ,altogether1 approximately #bc tons of meteoritic material from the ,ussuri fall are now in the collection of the ,meteorite ,committee of the ,academy of ,sciences1 ,moscow1 while another #dg tons are believed to still be buried in the ,ussuri crater field4 ,illustration3 ,,courtesy ,,of ,e4 ,l4 ,,krinov ,an individual ,ussuri meteorite with fusion crust and characteristic surface sculpturing produced during high-speed flight through the resisting atmosphere4 ,the ,russian scientists carefully mapped the locations of the individual craters1 penetration funnels1 and meteorite recoveries4 ,they made geologic and magnetometric surveys of the crater field1 took aerial photographs of the entire area of fall1 and prepared a documentary motion-picture covering the activities of the various expeditions4 ,the area of the crater field has been set aside by the ,russian government as a sort of scientific preserve1 and is being made into the equivalent of what is termed a ,national ,monument in the ,u4,s4,a4 ,several of the typical craters are protected by overroofed shelters to preserve these features for generations yet to come4 #b4 ,a ,,meteorite ,,falls ,,in ,,the ,,wheatland1 ,u4,s4,a4 ,february #ah1 #aidh1 had been a pleasant day in northwestern ,kansas and as the supper hour approached1 the sky remained blue and cloudless4 ,shortly before #e3jj p4m41 a few people were still out of doors4 ,an eleven-year old girl was hanging up the last of the family wash on a high clothesline4 ,in the late afternoon sunshine1 a woman and her son were enjoying a walk around the back yard of their home on a large ,kansas ranch4 ,outside his house1 a ten-year old boy was playing basketball with friends4 ,a veteran of ,world ,war ,,ii was loading fodder in a silo4 ,in the feedlot of his ranch1 a farmer was stacking hay4 ,a filling station attendant was working outside at the pumps1 grateful for a spell of milder winter weather4 ,without warning1 a large and very bright fireball streaked across the clear sky from southwest to northeast4 ,ominous-looking white smoke-clouds mushroomed up from points in the fireball's path4 ,shortly after the fireball disappeared1 loud explosions and rumbling sounds drove thousands of people out into the open4 ,the whole astonishing luminous display was over in a few seconds1 but the strange clouds and the frightening sounds that followed the fireball's passage continued much longer4 ,although startled by the brilliant fireball and the strange thundering noises1 the young girl1 whose face had been turned skyward as she hung up the clothes1 noted very carefully where she had seen the fireball disappear behind the tallest building in her home town4 7,her sighting was later of great value to field parties from the ,institute of ,meteoritics of the ,university of ,new ,mexico47 ,the woman and her son were amazed to see an angry1 boiling white cloud tinged with red developing overhead in the blue sky and to hear strange whizzing noises in the air around them4 ,the boy playing basketball heard a peculiar whistling or hissing noise just as he was ready to shoot a basket and1 on looking up1 saw the ball of fire slanting earthward4 7,this boy's report was of particular interest1 since it related to an unusual type of 8sound0 that travels at the speed of light rather than at the velocity of ordinary soundwaves47 ,as a cannonading louder than any the veteran had heard on the battlefields of ,europe echoed over the rolling countryside1 he went temporarily into a state of shock4 ,the farmer stacking hay heard several explosions1 felt a violent air blast1 and finally heard a solid object strike the ground 8with a smack10 as he put it1 8like a clod hitting the earth40 7,later1 field searchers found that this man lived only about two and a half miles south of the point where the largest fragment of the meteorite fell47 ,shortly after the passage of the fireball1 the filling station attendant felt the legs of his trousers flap as if he were standing in a high wind1 although he was more than #aa miles distant from the actual path along which the fireball moved on its way to the earth4 ,as in the case of the ,ussuri fall1 which had occurred about a year earlier1 farm animals1 chickens1 and dogs were terrified by the strange and noisy event4 ,cattle tried to run through a fence to escape the deafening racket4 ,a fine pair of horses panicked and ran headlong into a narrow gully1 the walls of which collapsed on them during their struggles4 ,chickens dashed for the henhouse1 screeching and cackling all the way4 ,a dog that feared lightning jumped behind a haystack and finally ran to his master in alarm4 ,although the majority of the people did not see the fireball itself1 they were driven out-of-doors by the violent concussions that followed its passage1 and thus got out under the open sky in ample time to see several large1 turbulent white clouds mushrooming far overhead4 ,from these clouds1 a thick powder or dust filtered down through the air and collected on the surfaces of stock ponds and water tanks4 ,some people thought the peculiar clouds were similar to those produced by atom bomb explosions4 ,many suspected that a ,v-#b rocket had 8run away0 from the proving ground at ,white ,sands1 ,new ,mexico4 ,one man disagreed with the opinion of his friends that the military had been experimenting and declared that it was 8the ,lord who was experimenting60 ,the ,february #ah meteorite fall caused great excitement throughout ,kansas and ,nebraska1 and it was the chief topic of conversation for days among the residents of the many small farming communities along the western half of the ,kansas-,nebraska state line4 ,the ,ussuri fall was studied by ,russian scientists exclusively1 and we have of necessity given1 in ,chapter #a1 a secondhand account of the fall and surveys the ,russians made2 but field parties from the ,institute of ,meteoritics conducted on-the-spot investigations of the ,norton1 ,kansas fall4 ,as we were members of several of these field parties1 the story to follow is a firsthand report4 ,a little before #f3jj p4m4 on ,february #ah1 word of the mysterious explosion centering near ,norton1 ,kansas reached the ,institute of ,meteoritics1 in ,albuquerque1 ,n4 ,m41 through the kind offices of ,civil ,air ,patrol personnel4 ,since a number of early reports had described the incident as an airplane falling in flames1 it was only natural that the ,civil ,air ,patrol and similar groups would take an interest in the occurrence4 ,at once1 the staff of the ,institute began to interview eyewitnesses of the event through ,civil ,air ,patrol channels and by long distance telephone1 telegram1 and letter4 ,soon we had collected enough information to show clearly that a large meteorite fall had been responsible for the unusual light and sound effects that had startled the inhabitants of ,kansas1 ,nebraska1 and adjoining states4 ,by ,march #c1 the ,institute staff had made a first determination of the probable area of fall4 ,the center of this oval-shaped1 #h by #d mile area lay about #ae miles north-northwest of ,norton1 ,kansas and nearly on the ,kansas-,nebraska state line4 ,the meteorite had fallen in a region of wheat fields1 pasture lands1 and widely scattered farm houses4 ,the countryside there is open and gently rolling4 ,the small creeks winding through shallow valleys are marked in spring and summer by narrow bands of low green trees and bushes4 ,many of the hillsides are covered with unplowed buffalo sod4 ,illustration3 ,a fragment of the ,norton fall is removed still imbedded in the tough buffalo grass sod into which it penetrated4 ,on ,march #bd1 a field party left the ,university of ,new ,mexico to make a survey of this area4 ,unfortunately1 ,kansas blizzards can be as severe as any in ,siberia1 and although the scientists gathered many helpful reports from eyewitnesses of the fall1 heavy snow and high winds seriously hampered the work4 ,the information they collected1 however1 confirmed the accuracy of the ,institute staff's first determination of the probable area of fall4 ,late in the spring1 a farmer in this area found a 8strange stone0 on his land and held it for identification by the second ,institute party4 ,this strange stone--which smelled like sulfur and had metallic specks in it--was the first piece of the fallen meteorite to be recovered4 ,scientists and farmers soon found many other fragments during systematic searches of the rolling farm and pasture lands4 ,the fourteen-year-old boy who had been walking with his mother at the time of the fall discovered a #acj-pound fragment of the meteorite in a pasture that had already been carefully searched by grown-up meteorite hunters6 ,this find was one of the two largest fragments recovered from the entire fall4 ,the landing place of this large piece was marked only by a small hole in the sod1 but1 on prodding into this hole1 the boy struck something rather solid4 ,he ran at once to tell the lady who owned the pastureland1 and together they dug out the fine meteorite4 ,illustration3 ,the ,furnas ,county1 ,nebraska1 stony meteorite in place at the bottom of its #aj-;foot 8penetration funnel40 ,this discovery brought interest in finding meteorites to a fever pitch1 and it was soon possible to look in almost any direction and see farmers1 or their wives and children1 walking slowly across the fields and looking for meteorites4 ,finally1 in ,august1 two farmers cutting wheat in a field just a short distance north of the ,kansas-,nebraska state line found a deep hole when their tractor almost fell into it4 ,they investigated and discovered that a very large fragment of the meteorite had buried itself deep in the ground4 ,scientists from the ,university of ,nebraska and the ,institute of ,meteoritics carefully excavated this huge meteorite4 ,they found that the mass had plunged more than #aj feet into the earth4 ,quite by chance1 its lower surface had come to rest in the ashes of a long-buried primitive cooking site4 ,the excavated meteorite looked and felt like a huge stone4 ,actually1 it was stony in nature1 but of a texture so fragile that it had to be wrapped in tissue paper1 then in burlap1 and finally covered with a thick coating of plaster of ,paris before it could be lifted out of the ground4 ,those in charge of the removal of the meteorite borrowed this procedure from the paleontologists1 who use it in the removal of fossil tusks and bones that otherwise would crumble away4 ,after the great meteorite had been raised out of the excavation1 it was taken by truck to the ,university of ,new ,mexico1 in ,albuquerque4 ,there it was put on display beside the smaller #acj-pound fragment found in ,may4 ,by careful measurements1 scientists determined the weight of the main mass to be approximately #b1cfj pounds--a record weight for stony meteorites4#a ,this remarkable meteorite1 known as the ,furnas ,county1 ,nebraska1 stone1 is now a prized item in the collection of the ,institute of ,meteoritics4 ,illustration3 ,field party proudly surrounds the ,furnas stone in its protective 8armor40 ,as more and more finds were made in the area of fall1 we accurately recorded their weights and mapped their locations4 ,in this way1 we could tell how the pieces of the meteorite had distributed themselves according to size and weight over the oval-shaped area4 ,the smaller and lighter fragments were slowed down by air resistance and fell first1 while the #b1cfj-pound mass carried on beyond them and came to earth at the farthest point along the direction of flight4 ,the staff of the ,institute took many photographs of the meteorites that were found1 of the impact funnel made by the largest mass1 and of the excavation and removal of that giant stone4 ,some of these pictures were published in scientific journals1 others in magazine and newspaper articles4 ,a few of our best photographs are included in this chapter4 ,although the light and sound effects that accompanied the ,ussuri and ,norton falls were similar1 the meteorites recovered from them were not at all alike4 ,the ,ussuri specimens were masses of nickel-iron so malleable that on high-speed impact with hard rock they had held together and taken twisted and ragged shapes4 ,but the ,norton meteorites were very fragile stony masses1 many of which went to pieces either in the air or when they struck the ground4 ,almost all of the recoveries made of this very rare type of stony meteorite were fragments1 not whole specimens4 ,they somewhat resembled pieces of a strange whitish mixture of chalk and crystalline limestone containing tiny specks and lumps of nickel-iron4 ,many specimens were covered wholly or in part by a shiny varnish-like fusion crust1 varying in color from jet black through yellow to almost pure white4 ,illustration3 ,the ,furnas stone1 protected by its 8armor10 hangs suspended from the truck crane that raised it out of its deep 8penetration funnel0 in the earth4 ,the largest meteorite recovered from the ,norton fall was the #b1cfj-pound mass that formed the deep impact funnel4 ,the smallest ,norton specimens1 like their ,ussuri counterparts1 weighed no more than the thousandth part of a gram4 ,altogether1 nearly a ton and a half of meteoritic material from the ,norton fall was collected by the ,institute4 ,other small fragments may remain undiscovered in the ,kansas and ,nebraska wheatlands1 but1 unfortunately1 because of the soft and fragile nature of the material they are composed of1 it is likely that they have now weathered away so completely that they are no longer recognizable as meteorites4 ,our stories of the ,ussuri and ,norton meteorite falls show how hard scientists work themselves 7and others67 to find meteorites4 ,therefore meteorites must be important4 ,the two accounts given also make clear that investigators of meteorite falls are almost entirely dependent upon observations made by nonscientists4 ,scientists investigating meteorite falls greatly appreciate the help given them by children and adults alike4 ,field parties are powerless without it1 and we should like to encourage people of all ages to continue this type of valuable cooperation4 ,in ,chapter #g1 we shall tell more about how the individual observer of a meteorite fall can make his report really count4 ,illustration3 ,a close-up of the ,furnas ,county stone1 the largest stony meteorite ever recovered4 #c4 ,,found ,,and ,,lost ,,giants ,all meteorites are important from the standpoint of science1 but a few deserve special mention because of the human-interest stories connected with them4 ,first place among famous finds should no doubt go to the massive ,cape ,york1 ,greenland1 iron1 the largest recovered meteorite actually to have been weighed4 ,the ,eskimos called this enormous object 8,ahnighito10 which means 8,the ,tent40 ,robert ,e4 ,peary1 the discoverer of the ,north ,pole1 brought it to ,new ,york ,city by ship in #ahig4 ,his party had great difficulty hoisting the #cd-ton mass aboard4 ,later1 when the ship had put to sea1 she encountered a serious navigational hazard4 ,to the amazement and alarm of the crew1 the huge nickel-iron meteorite caused magnetic disturbances that severely affected the ship's compass4 ,another of the giant meteorites1 the #ad-ton ,willamette1 ,oregon1 iron1 became the center of a long legal battle in the early #aijj's4 ,the man who originally found the meteorite and recognized its true nature felt that because the iron was on the surface of the ground and not buried beneath it 7as the ore of a metal would have been71 there was no reason why he should not move the mass from the place of find to his own property1 three-fourths of a mile away4 ,he did this very laboriously by means of a log-timber car1 a capstan with wire rope1 and a small horse4 ,on learning what the finder had done1 the company that owned the land from which the meteorite had been removed put its attorneys on the job of recovering the 8purloined0 meteorite4 ,the ,oregon courts1 bowing to decisions made in previous cases involving ownership of meteorites1 brought in a verdict favoring the owners of the land4 ,although the finder of the ,willamette meteorite lost the decision1 he nevertheless won the distinction of being the only man to have successfully made off with a treasure weighing #ad tons6 ,illustration3 ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,peary's photograph of the ,cape ,york meteorite as it was being moved for loading aboard his ship4 ,illustration3 ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,arrival of the #cd-ton iron mass at the ,american ,museum of ,natural ,history1 ,new ,york ,city4 ,the biggest meteorite of all1 of course1 is the one that 8got away40 ,in #aiaf1 a captain in the ,mauritanian army was taken by a native guide1 secretly and at night1 to the site of a colossal iron meteorite located in the dunes of the ,adrar desert1 in the far western reaches of the vast ,sahara4 ,the officer described the mass as measuring #ajj meters 7over #cjj feet7 by #dj meters 7over #abj feet71 with the third dimension hidden by the sand dunes4 ,according to him1 the mass 8444 jutted up in the midst of sand dunes that were covered by a desert plant1 the sba1 and it had the form of a compact1 unfissured parallelopiped4 ,the visible portion of the surface was vertical1 dominating in the manner of a cliff1 the wind-blown sand that was scooped away from the base of the mass so that the summit overhung2 and that portion exposed to eolian wind erosion was polished like a mirror40 ,the captain1 at the request of his uneasy guide1 returned from his hurried excursion without taking notes or making a map4 ,but he did bring back a small #aj-pound fragment of iron which he had found lying on top of the giant mass4 ,this small fragment later proved to be a genuine meteorite1 and is the only known specimen of the famous ,adrar mass4 ,it is preserved at present in the ,museum of ,natural ,history at ,paris4 ,illustration3 ,j4 ,,otis ,,wheelock ,,photo ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,man and boy carrying off the famous 8purloined0 ,willamette meteorite on a homemade dolly car with wheels of tree-trunk sections4 ,note hole piercing this #ad-ton chunk of iron4 ,what has been called a conspiracy of silence among the natives of the ,adrar area and the inhospitable nature of the region itself have successfully preserved the secret of the location of the enormous metallic mass described by the captain4 ,the native guide died1 apparently of poison1 and although many inhabitants of the region are no doubt familiar with the whereabouts of the mass 7whatever it is671 those questioned have consistently denied knowledge of its very existence4 ,all recent attempts1 not only by military but even by scientific expeditions1 to relocate the gigantic metallic mass have failed4 ,the whole ,adrar case remains an intriguing puzzle to be unraveled1 it is hoped1 by future generations of meteorite hunters4 ,another 8lost0 meteorite is one composed of stone and iron4 ,the ,port ,orford1 ,oregon1 stony-iron 7as it is now named7 was originally found in #ahei by a ,u4,s4 geologist who was engaged in a survey of what were then the ,oregon and ,washington ,territories4 ,according to him1 the mass was quite irregular in shape and 8#d or #e feet of it projected from the surface of the mountain10 while it was 8about the same number of feet in width and perhaps #c or #d feet in thickness40 ,he broke off a small fragment of it 7far smaller than the one taken from ,adrar7 and packed this specimen away with his collection of rock and mineral samples4 ,years later1 the geological collection was cataloged and analyzed in the ,east4 ,at that time1 the fragment collected in #ahei was found to be a piece of a stony-iron meteorite4 ,after that1 scientists and others made many attempts to rediscover the main mass of the large ,port ,orford meteorite1 all of them unsuccessful4 ,today the sum total of material recovered from this stony-iron amounts to #be grams in the ,u4,s4 ,national ,museum1 about #d grams in the ,natural ,history ,museum of ,vienna1 and a few tiny specks in the ,museum of the ,geological ,survey of ,india4 ,the ,red ,river1 ,texas1 iron is still another famous meteorite4 ,it was originally discovered by ,pawnee and ,hietan ,indians1 and a group of them took a party of traders1 in #ahjh1 to the site4 ,two years later1 two rival parties1 each led by a man who had been a member of the #ahjh trading expedition1 began a search for the meteorite4 ,the members of one of the two parties were from ,nacogodoches1 ,texas4 ,they reached the meteorite first but had left home so hurriedly on their eager hunt that they were not properly prepared to move so large a mass4 ,they went away from the site to get horses and a wagon1 after they had laboriously hidden the meteorite under a huge flat stone1 to prevent the other party from finding it4 ,the members of the other party1 hailing from ,natchitoches1 ,louisiana1 set out better prepared4 ,after a lengthy hunt1 they finally found the hidden meteorite4 ,using tools they had the foresight to bring1 they built a truck wagon and drove away with their prize4 ,eventually1 the ,red ,river meteorite1 weighing #a1fce pounds1 became a part of the collection at ,yale ,university4 ,but two other1 smaller1 masses of the same metal1 known in the early days to the ,pawnees and a few traders1 remain still undiscovered in the ,red ,river area4 #d4 ,,when ,,is ,a ,,crater ,a ,,meteorite ,,crater8 ,not all meteorites form craters at impact1 as the larger ,ussuri fragments did4 ,even the largest mass of the ,norton meteorite merely buried itself in a funnel-like hole only about #aj feet deep4 ,and the ,russian investigators found a number of the lighter ,ussuri fragments at the bottom of small penetration funnels4 ,cosmic missiles that are large enough to blast out craters in the ground are of particular interest to science1 however1 not only because of the extraordinarily intense light1 sound1 and other effects that accompany their fall1 but also because they produce characteristic and long-lasting basin-like features in the outer shell of the earth4 ,natural processes that change the surface features of the earth have long been the subjects of field studies by scientists4 ,geologists have carefully investigated the major folds formed in the earth's crust by mountain-building forces1 the clefts and depressions resulting from earthquake activity and erosion1 and the vast plains leveled off by the scouring action of great ice-sheets4 ,all of these different natural processes1 though1 have one thing in common3 their source is the earth-body itself4 ,they take place either within the earth's crust as a result of local shifts or changes in pressure 7like earthquakes and volcanic eruptions71 or on the surface of the earth as a result of the action of water or of changes in temperature 7like erosion and glaciation74 ,on the other hand1 meteorite impact craters are not formed by earth-processes at all4 ,as we have seen1 they result when large bodies of matter from the regions of space outside the earth chance to strike the surface of our planet at high speed4 ,the study of meteorite craters is therefore a special field4 ,it is also one of quite recent development2 not until #aije was the first meteorite crater recognized as such4 ,the first thing to be said on this subject is1 of course1 that not all holes in the ground1 however large and impressive1 were necessarily formed by the impact of meteorites4 ,features that resemble meteorite craters may result from certain ordinary earth-processes4 ,for example1 the rock layers underlying a particular area may be dissolved away by waters circulating beneath the surface of the ground4 ,the overlying crust will eventually collapse into the empty space1 and what geologists call a 8sink hole0 or a 8sink0 is formed4 ,many such sinks surround the genuine meteorite crater near ,odessa1 ,texas1 and at times have been mistaken for the real thing4 ,since there is some possibility of confusion about whether or not a hole in the ground is a meteorite crater1 it is comforting to know that scientists have come up with a handy set of rules for reaching a decision on this point4 ,these rules can be stated in the form of several questions that crater-investigators should ask themselves3 ,have you found meteorites in or near the crater-like feature8 ,in its vicinity1 have you found pieces of country rock that show the effects of high temperature and pressure 7melting or crushing78 ,did people actually see a meteorite come to earth at the point where the crater is located and where1 to their certain knowledge1 no crater existed before8 ,if the answer to all--or even one--of these questions is yes1 then it is quite likely that the crater-like feature is actually a meteorite crater4 ,naturally1 if the answer to the first question is yes1 the matter is practically settled in favor of the meteoritic origin of the feature4 ,if the impact has taken place in horizontally bedded rock strata--that is1 in flat beds of rock lying one on top of another like the layers in a stack of griddle cakes--a meteorite crater will have a characteristic rim of upturned or even overturned rock layers4 7,none of the ordinary sink holes near the ,odessa crater show such rims47 ,in addition1 pieces of rock shattered and thrown out by the impact will be found in all directions around the crater4 ,the amount and size of this fragmented material will decrease with distance outward from the crater4 ,a list of the recognized 7or genuine7 meteorite craters of the world is given in the table on page #fe4 ,all of these craters except the two ,russian ones were formed many thousands of years ago1 and1 in most cases1 the earth processes of erosion and weathering have by now dimmed the sharp outlines of their rims and silted up their deep interior funnels until only basin-like bowls remain4 ,illustration3 ,cross-section showing the manner in which horizontally bedded rock strata may be broken and tilted upward by the impact of a crater-forming meteorite4 ,this schematic diagram is based on excavations at several meteorite craters4 ,you may have visited the very first crater in the world to be recognized by scientists as a meteorite crater4 ,this huge basin1 now known as the ,canyon ,diablo meteorite crater 7although often referred to incorrectly as 8,meteor ,crater071 lies about #bj miles west of ,winslow1 ,arizona4 ,it is the best known of all the craters listed in the table because in recent years it has been developed under private ownership as one of the leading tourist attractions on ,u4,s4 ,highway #ff4 ,from the paved road that turns off ,highway #ff toward the crater1 the visitor sees the rim as a chain of low1 hummocky1 tan-colored hills which contrast sharply with the grayish or reddish hue of the desert plain4 ,the outer slopes of the crater rim rise very gently from the level plain in which the crater was formed1 and they are covered with rock fragments of various sizes thrown out at the time the meteorite struck the earth4 ,this fragmented material ranges in size from tiny particles of 8rock-flour0 as soft as face-powder to gigantic solid masses like ,monument ,rock1 which is estimated to weigh #d1jjj tons4 ,field parties have found #ej- to #ajj-pound fragments of the limestone layer underlying the ,canyon ,diablo area at distances of #a to #b miles from the crater4 ,sizable rock and meteorite fragments out to distances of #f miles from the rim have turned up1 and smaller fragments of both materials at even greater distances4 ,on their first visit to the ,canyon ,diablo crater1 people are always astonished at the steepness of the inner walls of the crater and at the very great size of its bowl4 ,this crater is more than #d1jjj feet across and #egj feet deep4 ,it is the largest recognized meteorite crater so far discovered in the world1 although other larger1 basin-like features elsewhere on the surface of the earth have been suspected but not proved to have a similar origin4 ,illustration3 ,,courtesy ,,of ,,trans-,,world ,,airlines ,aerial view of the ,canyon ,diablo1 ,arizona1 meteorite crater4 ,when the ,canyon ,diablo meteorite plunged into the horizontally bedded rock layers underlying the area of fall1 the force of the explosion following the impact actually bent these layers upward4 ,all around the inside of the crater1 the rock strata tilt away from the center at steep angles4 ,cowboys1 ranchers1 and scientists have found thousands of solid nickel-iron meteorite fragments around the crater4 ,the largest of these weighs #a1djf pounds4 ,the smallest spherules and grains are almost or quite microscopic in size4 7,these tiny granules have been well known to scientists since #aije in spite of current fables claiming that they are a recent discovery47 ,in the rim and on the plain outside the crater1 large and small shale balls1 composed of weathered meteoritic material1 were found in considerable numbers in the early days4 ,along with many solid iron meteorites1 shale balls have also been found at various depths in recent times by field parties from the ,institute employing specially designed meteorite detectors4 ,in the first two decades of the twentieth century1 investigators sank 7at great expense67 a number of shafts and drill holes in the interior and on the south rim of the crater1 in unsuccessful attempts to locate the supposed 8main mass0 of the ,canyon ,diablo meteorite4 ,most authorities now believe1 however1 that the extremely high temperatures1 developed at the time the ,canyon ,diablo meteorite penetrated into the earth1 changed almost all of the gigantic cosmic missile into vapor4 ,illustration3 ,view of the interior of the ,canyon ,diablo crater showing the steep inner slopes of the huge basin4 ,no better example of an ancient meteorite crater has been found than this one near ,canyon ,diablo4 ,the other craters listed in the table 7even the two recently formed ones71 while bearing resemblances to it1 also show individual differences from it4 ,some1 like ,henbury1 ,campo del ,cielo1 and ,haviland1 are not single craters but rather consist of fields of craters4 ,in these cases1 the earth was struck not by a single large meteoritic body that held together right down to impact1 but either by a 8swarm0 of meteorites traveling together through space or by the fragments of a large meteorite that separated into pieces shortly before it struck the surface of the ground4 ,again1 the type of ground into which the meteorite strikes affects the character of the craters formed4 ,as an illustration1 the ,wabar1 ,arabia1 craters were not smashed out of sedimentary1 horizontally bedded rock layers 7as was the ,canyon ,diablo crater7 but were formed in clean desert sand dunes4 ,in this case1 the crater rims are composed primarily of almost pure silica-glass formed by the fusion of the sand at the time of impact4 ,it is not hard to imagine the terrific boiling and frothing up of melted sand and meteoritic material that must have accompanied the formation of the ,wabar craters4 ,except for ,podkamennaya ,tunguska and ,ussuri1 the craters listed in the table were formed1 as we have mentioned1 a great many thousands of years in the past4 ,just how many thousands is a difficult question to answer1 for all of our estimates must necessarily be made on the basis of indirect evidence rather than on direct observation4 ,illustration3 ,before impact of ,canyon ,diablo meteorite1 these rock layers were horizontal4 ,paleontologists1 geologists1 and other scientists give us an age of from #bj1jjj to #gj1jjj years for the ,canyon ,diablo crater4 ,the discovery of the fossil remains of a prehistoric horse buried in the ,odessa1 ,texas1 crater fill has shown that the age of that crater is not less than #bjj1jjj years4 ,the oldest craters known in the ,united ,states are the ,haviland group produced by the ,brenham1 ,kansas1 meteorites4 ,long-continued weathering has almost completely worn down the rims and covered up the craters of this group4 ,on the basis of the rate at which nickel-oxide has spread out into the soil about a large deeply buried ,brenham meteorite1 calculations carried out at the ,institute of ,meteoritics have led to a tentative age of more than #fjj1jjj years for the ,kansas craters4 ,perhaps the oldest meteorite crater of all is the one blasted into what the geologists identify as pre-,cambrian quartzite at ,wolf ,creek1 ,western ,australia4 ,even the highly resistant iron meteorites found around this crater have almost completely weathered away4 ,only tiny specks and thin veinlets of metal are now visible on the cut surfaces of meteorites that1 untold hundreds of thousands of years ago1 were solid masses of nickel-iron4 ,you may have noticed that the widely publicized circular1 water-filled ,chubb crater in the ,quebec ,province of ,canada was not included in the table4 ,this ,canadian feature was left out because the answer to each of the three questions listed earlier in this chapter is no4 ,illustration3 ,,courtesy ,,of ,,william ,a4 ,,cassidy ,two of the deeply weathered meteorites found at ,wolf ,creek crater in western ,australia4 ,the field parties that have carefully searched the ,chubb crater and its surroundings1 even when they used one of the ,institute's powerful drag magnets1 were unable to find any trace whatever either of meteorites or of such weathered remains of meteorites as show the true nature of the ,wolf ,creek crater4 ,furthermore1 no searcher has discovered any fragments of ordinary rock showing the effects of the extreme heat and pressure that accompany large-scale meteoritic impact4 ,finally1 the meteorite supposed by some to have produced the ,chubb crater was not a recorded witnessed fall1 for the crater is of very ancient origin indeed4 ,perhaps further search of the ,chubb crater site and especially of the debris in its deep1 water-filled interior will succeed in bringing to light either specimens of meteorites or of silica-glass or other products of meteoritic impact4 ,if so1 then and only then will identification of the ,canadian crater as a meteorite crater be justified4 ,up to this point1 we have talked only of very old meteorite craters4 ,but two crater-producing meteorite falls have occurred within this century1 both in ,siberia4 ,the ,ussuri fall was one of these and the more recent of the two4 ,the earlier and more unusual fall took place on ,june #cj1 #aijh1 at about #h3jj a4m41 approximately #dj miles northwest of the trading post of ,vanovara4 ,a fireball exceeding the sun in brilliance flashed across the sky and was followed by extremely violent airwaves and earth-tremors4 ,the pressure wave in the atmosphere set up by this meteorite fall was strong enough to damage roofs and doors of houses near the point of impact1 as for example1 in the village of ,vanovara4 ,on both rivers and lakes in the area of fall1 the pressure wave in the air piled up high1 sharp-fronted water waves that resembled the bores on the ,seine and ,severn and that upset fishing craft and swamped other small boats4 ,throughout a wide region at somewhat greater distances from the impact point1 tidal-like bores were raised on rivers and lakes4 ,so gigantic was the atmospheric disturbance1 that it was detected at almost every station in the world where sufficiently sensitive barometers were in operation4 ,eyewitnesses of this meteorite fall said that at the time the fireball passed near them1 they felt almost unbearable heat4 ,a huge 8fiery pillar0 rose above the point of impact1 which by good fortune was in a desolate and almost uninhabited swampy basin between the ,chunya and the ,podkamennaya 7i4e41 8,stony07 ,tunguska rivers4 ,the meteorite fall takes its name from the latter stream4 ,the central portion of the region of impact is marked not only by a number of craters in the swampy terrain1 but also by mute evidence of the extraordinary destructive power of the ,podkamennaya ,tunguska meteorite4 ,over an area of many square miles1 the explosion blew down the standing forest so that the tops of the overthrown trees 7estimated by the ,russians to number more than #hj1jjj1jjj67 all point away from the impact center4 ,the intense heat charred the trunks and branches of the trees in this area in much the same way as the heat from the first of all atomic bomb explosions scorched the desert shrubs around the test site in south-central ,new ,mexico4 ,within the area of fall1 countless reindeer belonging to the native ,tunguse herdsmen were killed1 only their charred carcasses remaining4 ,how great the heat released at impact was may be judged by the well-established fact that the prized silver samovars of the nomads were found melted amid the debris of their flattened camps4 ,in at least one instance1 a ,tunguse was so overcome by the terrible event he had witnessed that he was 8sick for a long time40 ,the whole impact-region came to be considered as accursed by the natives1 who abandoned the use of all trails crossing it4 ,for many years the ,podkamennaya ,tunguska fall was neglected1 partly because of the remoteness of the area in which it occurred1 partly because of unsettled conditions in ,russia2 but chiefly because1 in general1 the ,russian scientific and governmental officials simply did not believe the 8fantastic0 tales concerning the fall told by the native ,tunguses1 from which we have given a few details above4 ,belated study established1 however1 both the truthfulness of the ,tunguse reports and the exceedingly unusual character of the meteorite fall itself4 ,in spite of the overwhelming and1 in fact1 worldwide evidence that the ,podkamennaya ,tunguska fall was one of the greatest and most violent in history1 no meteorites have ever been recovered from any part of the region devastated by its impact4 ,it is the one and only true meteorite crater that is meteoriteless6 ,this strange circumstance led the senior author to suggest1 in #aida1 that the almost incredible ,podkamennaya ,tunguska incident had resulted from the infall of a meteorite that1 together with an equivalent mass of the earth-target1 was transformed into energy upon contact with our planet4 ,how can such extraordinary behavior be accounted for8 ,illustration3 ,,leonid ,a4 ,,kulik ,,photo4 ,,sovfoto ,infall of meteorite1 ,june #cj1 #aijh1 had this effect on a ,siberian forest4 ,see p4 #ee4 ,the most obvious explanation involves a new and wider concept of matter4 ,ordinary terrestrial matter is regarded as composed of atoms having positively charged nuclei around which negatively charged electrons revolve4 ,suppose that the situation shown in the first diagram were reversed so that the nucleus of the atom were negatively charged and the charges of the particles revolving about it were positive1 as in the second diagram4 ,matter built up from atoms like those in this diagram would bear somewhat the same relation to ordinary matter that -#b does to #b4 ,such matter is now known variously as reversed matter1 anti-matter1 or1 as it was first called by ,v4 ,rojansky1 contraterrene matter4 ,in recent years1 scientists at the ,university of ,california ,radiation ,laboratory have produced experimentally all the fundamental particles necessary for the creation of contraterrene matter4 ,what would happen now if a contraterrene meteorite penetrated into the ordinary matter of the earth8 ,the answer is that just as an electron and a positron mutually annihilate each other when they collide1 so the meteorite and an equal mass of the earth-target itself would vanish at the instant of impact4 ,the nearest simple analogy to the actual complex physical situation is represented by the familiar equation -#b #b #j4 ,unlike 8summing to zero0 in simple arithmetic1 however1 the disappearance of mass1 technically called its annihilation1 results in a release of energy1 as was long ago observed in the case of electron-positron annihilation4 ,where considerable masses are annihilated1 as in an ,a-bomb explosion1 the amount of energy released is tremendous1 as is now well known to everyone4 ,illustration3 ,a4 ,representation of the structure of an atom of ordinary terrestrial matter4 ,the nucleus is positively charged and around it circle negatively charged electrons4 ,b4 ,representation of the structure of an atom of contraterrene matter4 ,this is the reverse of the situation in 7,a74 ,the nucleus here is negatively charged1 and around it revolve positively charged electrons1 also called positrons4 ,the effect of such an energy release as would accompany the infall of a contraterrene meteorite would be a natural nuclear explosion of vast power4 ,such an explosion would account for all the sensational phenomena observed at the time of the ,podkamennaya ,tunguska incident2 and1 furthermore1 would explain why the ,russian investigators have never succeeded in recovering meteorites from this fall4 7,further details1 p4 #ajb47 ,if the ,podkamennaya ,tunguska meteorite was contraterrene1 then the soil in the impact area must have been made radioactive in the same way that the earth around the 8ground zero0 of a nuclear explosion is contaminated by radioactivity4 ,after the senior author had repeatedly urged ,russian scientists 7who are the only ones that have been permitted to visit the site of the ,podkamennaya ,tunguska fall7 to try to detect any long-lasting radioactivities that might still be present in the ground at ,podkamennaya ,tunguska1 such a radioactivity survey was finally carried out in the summer of #aifj4 ,according to an official report of the ,soviet news agency ,,tass1 the investigators obtained 8abnormally high radioactivity readings0 which the ,russians tentatively considered to be the result of 8a natural nuclear explosion0 occurring in the ,podkamennaya ,tunguska area on ,june #cj1 #aijh4 ,science-fiction fans in the ,u4,s4,s4,r4 would like to believe that this 8nuclear explosion0 resulted from the impact of a ,martian spaceship rather than a contraterrene meteorite4 ,reputable ,russian scientists1 however1 have shown how completely absurd this 8fable0 of a ,martian landing really is4 ,when and where will the next crater-producing fall occur8 ,perhaps on the earth1 perhaps on the moon1 for our nearest neighbor in space has also been the target of meteorites of huge size4 ,the effects of this meteoritic bombardment are shown by the rarest and most striking type of lunar crater3 that which exhibits long1 bright rays extending outward from the crater itself as the spokes of a wheel radiate from its hub4 ,these so-called ray-craters show to best advantage at or near the time of full moon1 when they become one of the most remarkable features visible on our satellite4 ,illustration3 ,g4 ,w4 ,,richey ,,photo4 ,,courtesy ,,of ,,yerkes ,,observatory ,the lunar ray-crater ,tycho4 ,in earlier days1 most scientists believed that the craters on the moon had all been formed by volcanic action4 ,now the pendulum of scientific opinion seems to have swung toward the view that all the thousands of lunar craters are the result of meteorite impacts that took place in the long distant past4 ,both views are better examples of how scientific 8fashions0 control men's minds than they are of explanations that really account for all of the observed facts--as any acceptable explanation must do4 ,those who have studied the moon most carefully from an uncomfortable seat in a cold observatory rather than from a warm1 comfortable armchair are well aware that instead of just one type of lunar crater1 there are really two quite distinct types4 ,no single 8explanation0 can be expected to explain satisfactorily lunar features as strikingly different as3 ,first1 the rare and distinctive ray-craters described above1 which are scattered at random over the moon1 just as the points of impact of meteorites are upon our own globe4 7,roughly defined1 a random distribution is one showing no apparent pattern4 ,for example1 if you were to throw a handful of rice up in the air1 the points where the grains of rice finally came to rest on the floor would be randomly distributed or very nearly so47 ,second1 the ordinary or 8run-of-the-mill0 craters sprinkled in profuse but non-random fashion over the visible face of our satellite4 ,the ray-craters on the moon are the counterparts of the meteorite craters on the earth4 ,this fact is shown not only by their random distribution1 but by the long1 bright rays which gave them their name4 ,on the earth1 rays of similar appearance1 composed of thrown-out material1 are one of the most characteristic features of explosion craters1 whether the cause of the explosion is the high-speed impact of a great meteorite or the detonation of a charge of high explosive 7either conventional or nuclear74 ,the hypothesis that meteorite craters do exist on the moon is therefore justified even though it applies to far fewer craters than its supporters believe4 ,as for the ordinary1 non-ray lunar craters1 these features are not at all volcanic craters in the usual sense4 ,one of the few good things to come out of ,world ,war ,,ii was the first satisfactory explanation of the 8run-of-the-mill0 craters on the moon4 ,jeremi ,wasiutynski1 a brilliant ,polish scientist forced to take refuge in ,norway1 sought to explain these craters as originating in convection processes4 ,while the term 8convection0 may not be familiar1 the role convection plays in filling the sky with beautiful clouds on a hot summer's day is well known4 ,such cloud formation results from convection in the gaseous free atmosphere4 ,much more remarkable and regular are the results of controlled convection in layers of liquids rather than gases4 ,laboratory investigation of the effects produced by convection processes in heated liquids formed the basis for ,wasiutynski's new theory4 ,according to this theory1 convection processes in the only partially solidified outer shell of the youthful moon could have given rise to great numbers of surface features having the size1 shape1 and distribution of the common lunar craters4 ,in far more satisfactory fashion than any other theory so far proposed1 the convection-current hypothesis of ,wasiutynski explains the many and distinctive characteristics of the non-ray craters on the moon4 ,,recognized ,,meteorite ,,craters ,,of ,,the ,,world ,,name ,,location ,,date ,,of ,,recognition ,canyon ,diablo ,coconino ,county1 ,arizona #aije ,odessa ,ector ,county1 ,texas #aibi ,henbury ,mc,donnell ,ranges1 ,central #aicb ,australia ,wabar ,rub' al ,khali1 ,arabia #aicb ,campo del ,cielo ,gran ,chaco1 ,argentina #aicc #b;,haviland 7,brenham7 ,kiowa ,county1 ,kansas #aicc ,mount ,darwin ,tasmania #aicc #c,podkamennaya ,tunguska ,yeniseisk ,district1 ,siberia #aicc ,box ,hole ,station ,plenty ,river1 ,central #aicg ,australia ,kaalijarv ,oesel1 ,estonia #aicg ,dalgaranga ,western ,australia #aich ,ussuri 7,sikhote-,alin7 ,eastern ,siberia #aidg ,wolf ,creek ,wyndham1 ,kimberley1 #aidh ,western ,australia ,aouelloul ,adrar1 ,western ,sahara #aieb #e4 ,,heaven ,,knows ,,where ,,or ,,when ,meteorites have been falling upon our planet for a long time--how long1 it is hard to say with accuracy4 ,up to now1 no specimens certainly identified as meteorites have been found in ancient rock layers4 ,scientists have been able1 however1 to estimate the age of several meteorite craters on the basis of the degree of weathering not only of the crater rims1 but also of the meteorites found around the craters4 ,age estimates have also been based on the ages of fossils found in silted-up crater interiors and on other related indirect evidence4 ,as we have already noted1 the ,canyon ,diablo1 ,arizona1 crater is thought to be #bj1jjj to #gj1jjj years old4 ,the ,odessa1 ,texas1 crater is at least #bjj1jjj years old2 and the ,haviland 7,brenham71 ,kansas1 craters more than #fjj1jjj years old4 ,clearly1 meteorite falls have been occurring over a very long period of earth history4 ,for many years1 scientists have studied the distribution of recovered meteorites around the world in an effort to find out whether there are any places on the land surface of our globe where meteorites have fallen in unusually large numbers4 ,the idea that any particular spot on the land surface of the earth might in some way attract more meteorites to it than other locations seems unreasonable because of the very nature of the target presented by our planet to the meteorites wandering through space4 ,not only is the earth in motion1 but it is in very complicated motion4 ,our earth revolves about a sun which is also in motion through space4 ,at the same time1 the earth is rotating on its axis4 ,a single point on the surface of the earth therefore traces a very erratic path in space with the passage of the years1 and the likelihood that this particular point would be struck by more than one meteorite 7if indeed by one67 must be very small4 ,studies have shown that the people of the earth have a great deal more to do with 8concentrations0 of meteorite recoveries than anything else4 ,population density is the first important factor4 ,clearly1 the more people living in a given area1 the higher the probability that a meteorite fall will be seen and reported and that the fallen mass itself will be recovered4 ,a prime example is ,india1 one of the most densely populated regions of the world4 ,of the #ajb meteorites recovered in that country up to #aiec1 #ig were of witnessed fall4 ,this extremely high proportion of falls is undoubtedly due to the fact that for centuries such an event could hardly have taken place in that country without attracting the attention of large numbers of people4 ,apparently1 the majority of ,indian meteorites have been recovered as they fell1 for only #e unwitnessed falls are recorded for that country4 ,on the other hand1 from ,french ,west ,africa only #e falls and #c finds have been reported throughout an area slightly larger even than ,india's4 ,this country thus provides an example of a sparsely populated region1 in many provinces of which a meteorite fall might pass unobserved1 and a fallen meteorite might remain undiscovered4 ,a second factor is the degree of civilization reached by the inhabitants of a particular area4 ,those regions of the world which have been settled the longest and which have seen the development of the higher cultures will be the most likely to support a populace that will take an interest in and report the occurrences of natural events like meteorite falls4 ,such a populace will also be more likely to bring suspected meteorites to the attention of experts4 ,for example1 up to #aiec1 #ee witnessed falls and #c unwitnessed falls were known from ,france1 a country of relatively small area1 but with a high population density and an advanced degree of civilization4 ,from the whole vast area of ,siberia1 on the other hand1 only #bj meteorite falls and #bc finds have been reported during the same interval4 ,in the past1 scientists have suggested that various natural forces1 such as the magnetic field of the earth or the attraction of high and massive mountain ranges1 might cause more meteorites to fall in one place than another4 ,but all available evidence indicates that this is not the case4 ,the fall of meteorites upon the earth has been and is a process that shows no apparent pattern4 ,only 8human0 factors 7like population density and scientific interest in meteorites7 can be considered as accounting for any concentrations of meteorite falls in particular regions or countries4 ,in historic times1 the number of man-built structures 7houses1 barns1 hotels1 office buildings1 etc47 has increased tremendously4 ,such structures have presented an ever-expanding target to hits by falling meteorites4 ,on pages #gc1 #gd is a listing of some of the meteorites that have struck and damaged buildings during the last #aej years or so4 ,the items included in this list were chosen on the basis of interest1 authenticity1 and concreteness of detail4 ,the stories of all these meteorite falls are exciting1 but none more so1 perhaps1 than that of the ,beddgelert1 ,north ,wales1 stone4 ,this meteorite fell in the small hours of the morning on ,september #ba1 #aidi4 ,not many people saw the fireball that accompanied its descent because of the early hour 7#a3de a4m471 but one of the few persons who happened to be outside said that it resembled a huge rocket as it flashed across the sky4 ,he also reported that the appearance of the fireball nearly frightened the swans in the local park to death1 the birds fleeing in all directions4 ,the manager of one of the hotels in ,beddgelert simultaneously was awakened from a sound sleep by the barking of his dog4 ,this was an unusual occurrence1 and the man was surprised by it4 ,while he was trying to account for the dog's peculiar behavior1 he suddenly realized that something quite out of the ordinary was happening outside4 ,he heard a series of unevenly spaced bangs that he later compared to 8a naval broadside40 ,but as the noise died away and nothing further happened1 he went back to sleep4 ,about noon on the next day1 the manager's wife went into the upstairs lounge of the hotel1 a room right under a part of the roof4 ,she was astonished to find plaster dust all over the floor4 ,it had obviously come from a jagged hole in the ceiling4 ,and1 on the floor1 she found an odd-looking dark stone4 ,investigation showed that this stone had indeed fallen through the roof4 ,it had made a neat round hole in four overlapping thicknesses of slate1 shattered the underlying lath1 made a dent in the lower edge of an ,h-section iron girder1 and had finally broken through the plaster ceiling into the hotel's upstairs lounge4 ,although it was clear that the stone had come through the roof1 the hotel manager did not connect the event in any way with the peculiar noises he had heard during the preceding night4 ,he tried to cut the stone on an emery wheel1 but it was too hard4 ,that evening1 an old miner in the hotel restaurant recognized the stone as a meteorite4 ,many years before1 he had visited a museum and had seen specimens of meteorites on display there4 ,the slabs of slate penetrated by the meteorite would have provided good evidence as to the speed of the cosmic missile at the time it struck the roof4 ,but1 unfortunately1 these appear to have been thrown away at the time the roof was repaired4 ,this fact is mentioned to show that important scientific evidence is sometimes unwittingly destroyed before investigators can get a chance to examine it4 ,along with the rapid increase in the number of man-made buildings has1 of course1 gone a simultaneous increase in the world's population itself4 ,a person does not present as large a target to a falling meteorite as a house or barn1 but even so1 if there were enough people on the earth1 it would seem that someone was bound to be hit sooner or later4 ,illustration3 ,g4 ,w4 ,,swindel1 ,,jr4 ,,photo ,,courtesy ,,of ,,alabama ,,museum ,,of ,,natural ,,history ,the ,sylacauga1 ,alabama1 stone meteorite and the roof 7note circle7 through which it plunged and struck a person4 ,actually1 the first authentic case of a person being struck by a meteorite did not occur until ,november #cj1 #aied4 ,even then1 the hit was an indirect one4 ,at ,sylacauga1 ,alabama1 a meteorite fell through the roof of a house1 went through the ceiling of the living room1 struck the top of a radio1 and--bouncing in a #f-;foot arc--hit the lady of the house1 who was taking a nap on the couch4 ,fortunately1 nearly all of the energy of the meteorite was spent by the time it struck the woman1 and1 moreover1 she was covered with two heavy quilts so that she was not critically injured4 ,but she did receive bruises serious enough to send her to the hospital4 ,the instances just given show that a number of meteorites have struck buildings and1 in one case1 a cosmic missile has hit a human being4 ,nevertheless1 such events are really quite rare4 ,in fact1 mathematical calculations indicate that1 on the average1 we can expect one meteorite to fall per township 7#cf square miles7 per #ajjj years4 ,a rate like this does not justify the loss of any sleep over the possibility that you might some time be hit by a falling meteorite6 ,,selected ,,list ,,of ,,meteorites ,,that ,,have ,,struck ,,and ,,damaged ,,buildings ,,name ,,and ,,location ,,type ,,approximate ,,weight ,,year ,baxter1 ,missouri stone #faa gm4#d #aiaf ,meteorite penetrated roof and struck a log joist1 which checked the fall4 ,the stone lodged in the attic4 ,beddgelert1 ,north ,wales stone #gid gm4 #aidi ,meteorite made a clean hole through #d thicknesses of slate roof4 ,it then shattered underlying wood1 made tiny dent in bottom edge of ,h-section iron girder1 and broke through plaster ceiling into hotel lounge below4 ,benld1 ,illinois stone #aggj gm4 #aich ,meteorite penetrated garage roof1 top of car1 and seat cushion4 ,it struck and put #a-;inch dent in muffler1 then bounded back up and became entangled in seat cushion springs4 ,bethlehem1 ,new ,york stone #aa gm4 #ahei ,meteorite struck the side of wagon house1 bounded off1 hit log upon ground1 bounded again1 and rolled into the grass4 7,a dog lying in the doorway of the wagon house jumped up1 ran out and seized the meteorite1 but dropped it right away1 probably because of the warmth and sulfurous odor of the stone47 ,branau1 ,bohemia iron #ai1jjj gm4 #ahdg ,meteorite penetrated into room where #c children were sleeping and covered them with plaster and debris4 ,they were unharmed4 ,constantia1 ,south ,africa stone #iii gm4 #aijf ,meteorite penetrated #b thicknesses of corrugated iron roofing and smashed ceiling4 ,kasamatsu1 ,japan stone #gba gm4 #aich ,meteorite penetrated roof of house and stopped on floor4 ,it went through roof tile1 -inch wooden roof-panel1 and layer of clay #a inch thick between them4 ,kilbourn1 ,wisconsin stone #ggb gm4 #aiaa ,meteorite went through #c thicknesses of shingles1 a #a-;inch hemlock roof board1 and a -inch hemlock floor board4 ,it then glanced in turn against the side of a manger and the stone foundation of the barn and finally penetrated #b inches into the clay floor of the barn4 ,pantar1 ,philippine ,is4 stone shower #aich ,sixteen stones were recovered2 thousands 8as big as corn and rice grains0 fell on roofs4 ,sylacauga1 ,alabama stone #chfc gm4 #aied ,meteorite penetrated composition roof material1 -inch wooden decking1 -inch wooden ceiling1 and interior wallboard4 ,it then hit a radio1 punching a #a-;inch hole in plywood top1 and bounced #ij towards the east1 striking woman lying on couch4 #f4 ,,finders ,,foolish1 ,,finders ,,wise ,people find a great many meteorites that were not seen to fall4 ,most of these landed on the surface of the earth at some time in the remote past or happened to fall in an originally unpopulated portion of the land area of the globe4 ,generally1 such meteorites are discovered entirely by accident1 although in recent years quite a few recoveries of unwitnessed falls have been made by design4 ,this has been the case during the systematic surveys with meteorite detectors conducted around such recognized meteorite crater areas as ,canyon ,diablo1 ,arizona2 ,odessa1 ,texas2 and ,wolf ,creek1 ,australia4 ,the different modes of discovery of meteorites not seen to fall are interesting in themselves4 ,the largest percentage of finds has unquestionably been made by farmers4 ,the ,plymouth1 ,indiana1 meteorite1 for example1 was plowed up or1 as the farmer nursing the rib bruised by his bucking plow would probably prefer to say1 8plowed into40 ,so were such meteorites as the ,algoma1 ,wisconsin2 the ,bridgewater1 ,north ,carolina2 the ,carlton1 ,texas2 and the ,chesterfield1 ,south ,carolina1 to name only a few4 ,a farmer found the ,kenton1 ,kentucky1 iron while he was cleaning out a spring4 ,another farmer was removing debris from an abandoned water well in an attempt to revive it when he discovered the ,richland1 ,texas1 iron4 ,a field drainage project brought the ,seelsgen1 ,poland1 iron to light4 ,a man planting an apple tree near his house dug out the ,mount ,joy1 ,pennsylvania1 iron1 and a farmer hoeing tobacco turned up the ,scottsville1 ,kentucky1 iron4 ,the second largest percentage of finds probably has been made by miners4 ,prospectors and placer miners have mistaken numerous iron meteorites for lumps of silver ore4 ,among these are the ,murfreesboro1 ,tennessee2 ,lick ,creek1 ,north ,carolina2 and ,illinois ,gulch1 ,montana1 irons4 ,the ,aggie ,creek1 ,alaska1 iron was raised by a gold dredge4 ,the gold miners recognized this meteorite as an unusual 8haul0 when it announced its presence by clanging loudly on the metallic screen of the dredge4 ,men at work on road construction are also to be thanked for chancing upon meteorites of unwitnessed fall1 for example1 the irons found by road crews at ,bear ,lodge1 ,wyoming1 and at ,bald ,eagle1 ,pennsylvania4 ,some meteorites have been 8found twice40 ,at ,opava1 ,czechoslovakia1 archeologists discovered seven pieces of meteoritic iron in a buried ,stone ,age campsite--the oldest meteorite collection so far on record6 ,apparently the paleolithic inhabitants of the ,opava region had gathered the heavy masses together and used them to bolster the fireplaces in their rude encampment4 ,investigators discovered the ,mesaverde1 ,colorado1 iron in the ,sun ,shrine on the north side of the ,pipe ,shrine ,house1 and the ,casas ,grandes1 ,mexico1 iron in the middle of a large room of the ,montezuma temple ruins1 carefully wrapped in linen cloth like a mummy4 ,members of an early archeological survey found the small ,anderson ,township1 ,ohio1 meteoritic specimens on altars in mounds of the ,little ,miami ,valley group of prehistoric earthworks4 ,some scientists believe that the ,american ,indians transported these specimens to ,ohio from the site of the ,brenham meteorites in ,kiowa ,county1 ,kansas4 ,illustration3 ,the ,lake ,murray1 ,oklahoma1 iron meteorite in place1 just as it was found4 ,see p4 #hj4 ,other modes of discovery fall into no pattern and must be regarded as merely curious4 ,a farmer plowing his field near ,pittsburgh1 ,pennsylvania1 came across a snake4 ,in looking for a suitable stone with which to kill it1 he first seized upon a mass of iron too heavy to lift4 ,after he had killed the snake with a handy rock1 the farmer's attention was drawn back to the small but remarkably heavy mass he had first tried to pick up4 ,he carted it off to the city1 where eventually it was recognized as a meteorite4 ,in another unusual recovery1 fishermen brought the ,lake ,okeechobee1 ,florida1 stone up from the waters of the lake in a net--the only such recovery recorded in the whole literature of meteoritics1 although three-fourths of all meteorites must necessarily fall into water on our ocean-covered globe4 ,again1 the members of the ,australasian ,antarctic ,expedition of #aiaa-aiad were surprised to find the ,adelie ,land1 ,antarctica1 stone lying on the snow some #bj miles west of ,cape ,denison4 ,because the true nature of meteorite finds has often been unrecognized--sometimes for many years--these masses have been put to some rather lowly uses4 ,the finder of the ,rafrti1 ,switzerland1 iron meteorite used it as a footwarmer1 and many of the heavy irons have been employed as haystack1 fence1 and barrel-cover weights1 or as anvils1 nutcrackers1 and doorstops4 ,illustration3 ,it's a whopper6 ,see p4 #hj4 ,some have fared better1 as did the #a1cge-pound ,la ,caille1 ,france1 meteorite1 which the people of the village used for two centuries as a seat in front of their church4 ,others1 however1 have fared even worse4 ,blacksmiths and assayers have smelted up and destroyed a number of iron meteorites either in the making of tools 7like plowshares1 axe-heads1 and knife-blades7 or in the quest for precious metals4 ,nearly all of the iron meteorite that was found by the farmer near ,pittsburgh was worked up by a blacksmith and lost to science4 ,even the stone meteorites have occasionally fallen victims to man's greed for gold4 ,miners who believed that the #hj-pound ,san ,emigdio1 ,california1 stony meteorite was gold-bearing mashed it to powder in an ore-crusher4 ,on the contrary1 people who1 in one way or another1 have become acquainted with the characteristics of meteorites have brought a number of these objects to the attention of scientists4 ,for example1 one of the ,university of ,nebraska men who worked on the excavation and removal of the large ,furnas ,county stone meteorite 7see ,chapter #b7 became keenly interested at that time in meteorites in general1 and took the trouble to learn as much as he could about them4 ,several years later1 after he had become director of a state park museum in southern ,oklahoma1 a large metallic mass was reported to him4 ,the finder of this mass of metal had known of its existence for some #bj years1 but had never succeeded in getting anyone to examine it carefully4 ,the former field worker took one look at the object and1 on the basis of his knowledge of meteorites1 concluded that it probably was a huge iron meteorite4 ,he immediately called the ,institute of ,meteoritics by long distance and was able to give such a wealth of significant details that a field party left at once for the site4 ,in this way1 the ,lake ,murray1 ,oklahoma1 meteorite was identified and recovered4 ,illustration3 ,the ,lake ,murray core mounted on the meteorite saw which cut it in half4 ,one of the worn soft iron saw-blades is held above the meteorite by the saw guides4 ,see pp4 #afg1 #afh4 ,the unoxidized central core of this iron weighed more than #fjj pounds4 ,before excavation this core was surrounded by a 8shell0 of oxidized meteoritic material several inches thick1 as shown on page #gg4 ,such a shell of oxide clearly indicated that the meteorite had been subjected to weathering in the ground for many thousands of years4 ,in general1 meteorites seen to fall--possibly because of the magnitude and impressiveness of the light and sound effects connected with their descent--have received respectful treatment after recovery4 ,most of them have been presented to men of science for study and eventual display in some museum collection4 ,even when kept by their finders1 the specimens usually have been well cared for4 ,after the fall of the ,flows1 ,north ,carolina1 meteorite in #ahdi1 the owner of the land on which it came down set the stone in a place of honor on top of a barrel fixed to a post4 ,on the post he put up the notice3 8,gentlemen1 sirs--please not to break this rock1 which fell from the skies and weighs #ai4e pounds40 ,this landowner obviously realized that nearly everyone has the unfortunate urge to hammer on strange rocks4 ,of course1 there have been exceptions to the respectful treatment of meteorites seen to fall4 ,the finder of one fragment of the ,zhovtnevy ,hutor1 ,russia1 fall tossed it into the stove1 and a farm woman lost another by throwing it at an unruly horse4 ,a peasant who thought meteorites possessed miraculous powers powdered up a piece of the diamond-bearing ,novo-,urei1 ,russia1 stone and ate it6 ,illustration3 ,a polished and etched face of the ,lake ,murray meteorite4 ,the length of the cut is a good #bc inches4 #g4 ,,landmarks1 ,,skymarks ,,detectors ,the chemist can easily obtain materials for his research work from reliable supply houses4 ,the meteoriticist 7as a scientist who studies meteors and meteorites is known71 is not this lucky4 ,he must search for the specimens he wishes to investigate wherever they may have landed on the wide1 wide earth4 ,this 8needle-in-a-haystack0 problem could rarely be solved if it were not for certain mathematical and instrumental aids that swing the balance in favor of the meteorite hunter4 ,when meteorites are seen to fall1 these aids can be brought into play only if certain information is supplied by eyewitnesses of the falls4 ,for this reason1 everyone ought to be acquainted with the facts about meteorite falls that scientists will need to know in order to make finds1 and should understand how these facts must be reported in order to be of maximum use to field parties4#e ,the problem of working out the path a fireball has followed in the sky boils down to this4 ,the investigating scientists must be able to fix the position in space of certain important points on the fireball's path4 ,this idea of fixing points is not really difficult at all4 ,suppose1 to take an analogy from baseball1 we have base runners on first and third4 ,these two players are intently watching their team's clean-up hitter1 who is 8crowding the plate40 ,consequently their lines of sight intersect at home plate and give a very good 8fix on0 its position1 as navigators say4 ,this is the way a fix can be obtained in two dimensions2 that is1 essentially1 in the plane of the earth's surface4 ,illustration3 ,a4 ,a fix determined in two dimensions4 ,the lines of sight of the runners on first and third intersect at x4 ,b4 ,a fix determined in three dimensions4 ,the lines of sight of the runners on the first and third intersect at x4 ,now1 let us move into the third dimension1 since a fireball's path through the atmosphere lies in space1 not in the 8flat0 plane of the earth's surface4 ,returning to our baseball diamond1 let us suppose that a helicopter with an enterprising photographer aboard hovers over the centerfield bleachers so that he can take pictures of the record crowd4 ,while the umpire is dusting off home plate1 the two runners on first and third simultaneously sneak a look to see what the helicopter is doing4 ,their lines of sight now intersect at the helicopter and fix its position in space4 ,similarly1 the location of a fireball path in space is determined by the fixing of certain points on the luminous streak seen in the sky4 ,instead of using only two intersecting lines of sight 7those of the runners on first and third in our analogy71 scientists investigating a meteorite fall try to collect as many different lines of sight as possible from people in the region above which the fireball streaked4 ,the more commonly determined points are those of the fireball's appearance and disappearance and those where 8explosions0 took place4 ,these points are generally located by use of the method we have described in some detail above1 the so-called intersecting-lines-of-sight method4 ,the most important point on a fireball path is the point of disappearance4 ,the most valuable single piece of information you can supply about a meteorite fall is as accurate an answer as possible to the question3 ,in what compass direction were you looking when you last saw the fireball8 ,this question has often been twisted around in newspaper and radio accounts into the meaningless question3 ,in what direction was the fireball going when you saw it8 ,one person cannot give the answer to the second question because from a single station it is impossible to determine the true direction of motion of an object seen in the sky4 ,one person can report only an apparent direction of motion1 which is of little or no value in locating the last point on the luminous path1 generally referred to as the 8end-point40 ,therefore1 though you cannot by yourself determine the actual direction in which a fireball is moving1 you can report the direction in which you were looking when you last saw the fireball1 that is1 due south1 southwest1 northeast1 etc4 ,illustration3 ,o is an observer squinting along the top of a ping-pong table4 ,a ping-pong ball rolls along the top of the table from ,b 7beginning7 to ,e 7end74 ,to the observer at ,o1 however1 the ball would appear to start at ,b and end at ,e if it rolled along any one of the dashed lines leading from ,,ob to ,,oe4 ,by means of a similar space-figure1 it can be shown that a single observer at ,o cannot determine the true direction of motion of a luminous object in the sky1 like a meteor4 ,scientists are eager to obtain reliable reports on the compass direction to the fireball's point of disappearance from as many widely separated eyewitnesses as possible4 ,they then can plot the individual lines of sight on a good map1 marking exactly where these lines intersect4 ,in this way1 the investigators can make reasonably accurate fixes of the position of the point on the earth's surface that is situated directly below the end-point of the fireball path1 as this end-point was seen in the sky by each pair of eyewitnesses4 ,instead of using the ordinary compass direction to a fireball's point of disappearance1 you may prefer1 as do astronomers1 to use the azimuth4 ,what we have been calling a 8compass direction0 is one that is expressed in terms of the cardinal points3 north1 south1 east1 west4 ,an azimuth is a direction stated in degrees4 ,rough azimuths can be taken with a compass1 but for accurate work1 a graduated circle1 like that on a transit or theodolite1 must be used4 ,astronomical azimuths begin at the south point and continue clockwise full circle to #cfj4 ,for example1 the lines of sight in the diagram1 p4 #hg1 could very well have been given as astronomical azimuths4 ,and1 in the diagram1 p4 #ia1 the line of sight ,c could have had the precise designation #aah and ,c that of #bbb4 ,every fix serves to guide field parties to areas that are to be carefully searched for fallen meteorites4 ,extra-thorough searches are made if the people living in a particular area reported that they heard meteorite fragments hissing and whining on their way to earth or heard the thumps of their impacts on the ground4 ,you will notice that so far we have been treating our problem as a two-dimensional one4 ,we have been working with directions only and have plotted out direction indicators on a map representing the plane of the earth's surface4 ,now1 as we did in our baseball analogy1 let us move into the third dimension4 ,illustration3 ,diagram 7not drawn to scale7 showing plotted compass directions to the last visible point on a fireball path4 7,the point denoted by ,l in next diagram47 ,black dots represent positions of various observers4 ,each arrowed line is directed toward the last visible point as it was estimated by the individual observer4 ,the oval area1 which includes points of intersection of all observed lines of sight taken in pairs1 marks out region in which meteorites have probably fallen4 ,if1 in addition to compass directions to the observed endpoint1 scientists can also obtain the apparent elevation1 in degrees1 of this point as seen by the various eyewitnesses1 then with the help of a little trigonometry1 they can fix the position in space of the end-point itself rather than the position of its projection on the surface of the earth4 ,this same procedure can be followed in fixing the space-position of any well-observed point on the fireball path4 ,it therefore becomes possible when both elevations and compass directions are reported for several points on the fireball path to determine the flight-path or1 as it is technically called1 the trajectory1 of the falling meteorite through the atmosphere4 ,trajectory determinations are of great scientific value4 ,you can estimate the compass directions and elevations to the important points on a meteorite trajectory at the actual time of fall4 ,or you can have the scientific field party make or check your measurement at some later time by setting up a surveying instrument at the very point from which you saw the fireball4 ,the accuracy of your measurements can be improved if you have been able to 8line up0 the point1 ,l1 at which you saw the fireball disappear1 with some familiar object on the horizon1 such as a church steeple1 a tall tree1 a telephone pole1 or a lightning rod on a farm building4 ,you will recall that an eleven-year old girl provided one of the field parties from the ,institute of ,meteoritics with an excellent observation of the point of disappearance of the ,norton fireball4 ,she was able to do this because she remembered just where it went out of sight behind a familiar landmark4 ,illustration3 ,method for locating a point on a fireball path4 7,in this case the point of disappearance1 ,l47 ,o ,first observer4 ,a ,apparent height of point of disappearance 7#ej74 ,c ,compass direction of point of disappearance 7,n #fb ,w74 ,o ,second observer4 ,a ,apparent height of point of disappearance 7#de74 ,c ,compass direction of point of disappearance 7,n #db ,e74 ,if the fall occurs at night1 you can help investigators greatly if you are familiar enough with the brighter stars to use them as 8skymarks40 ,you simply note as quickly and sharply as you can just where the fireball path was in reference to those prominent stars4 ,this alert observation of yours will at least be a great aid to investigators who are searching for meteorites that may have fallen from the fireball2 and1 moreover1 there is no telling what else your quick eye might have captured for science4 ,while looking through a window1 ,kayser1 the ,polish astronomer1 saw a fireball appear at ,rigel and move to ,sirius1 where it disappeared4 ,this observation of his proved to be one of the most accurate and significant ever made of the fall of a meteorite4 ,for it enabled the ,german mathematician1 ,galle1 to show that the ,pultusk meteorite1 which produced the fireball ,kayser saw1 came into the ,solar ,system from interstellar space6 ,it is very essential to carefully notice and mark the exact spot from which your observation was made so that you can return to it if scientists wish to set up surveying instruments there4 ,the map and side view of the ,norton ,county1 ,kansas1 meteorite trajectory show the practical results that the ,institute obtained by use of the intersecting-lines-of-sight method4 ,the fireball accompanying the ,norton meteorite fall appeared at ,a4 ,the first 8explosion0 took place at ,e1 the second at ,e1 and the fireball disappeared at ,l4 ,if markers were dropped straight down to earth from each point along the trajectory or flight-path of a meteorite through the atmosphere1 the line joining the points where the markers fell would be the earth-trace of this trajectory4 ,the directions of sight to these various points are indicated for people living in the towns along and near the earth-trace of the ,norton meteorite fall4 ,the solid-line arrows represent the direction of the point of disappearance2 the dotted-line arrows1 the point of appearance2 the dash-dot arrows1 ,e2 and the dashed arrows1 ,e4 ,the probable area of fall is shown as an oval-shaped area1 the longer axis of which is identical with the direction of motion of the meteorite4 ,illustration3 ,path of the ,norton meteorite4 ,the many fragments of all sizes recovered from the ,norton fall were all found within the bounds of this oval-shaped area1 although unavoidable errors of observation placed the center of the oval about #d miles too far to the north4 ,in addition to the questions about direction and elevation1 there are a few more that investigators of meteorite falls would like to have observers answer4 ,at what time 7determined as accurately as possible7 did the fall occur8 ,knowledge of this time is necessary if the path in which the meteorite was moving about the sun is to be calculated by scientists4 ,did you hear any sounds1 either while you were watching the fireball or after it disappeared8 ,if you heard such sounds as the whining or hissing of meteorite fragments flying through the air or the heavy thumps of their impacts on the earth1 then you were very close to where the meteorite came down6 ,how many minutes and seconds 7again determined as accurately as you can7 passed between the time when you saw the fireball vanish and the instant when you first heard sounds from it8 ,such sound data permit rough determination of the distance from the observer to the point where the meteorite fell4 ,how long did the sounds set up by the meteorite last1 and in what direction did these sounds seem to die out8 ,if you or your neighbors find fragments that you suspect are pieces of the meteorite1 these specimens should be shown to the investigating field parties at once--preferably undisturbed and in the very places where they fell4 ,in any event1 the suspect masses should not be hammered on and broken up6 ,even as late as #aieh in a country as science-conscious as ,germany1 a beautiful stony meteorite1 seen to fall and speedily found by an alert group of children playing out of doors1 was deliberately broken up into #e pieces in order that each of the children 7aged #i years and up7 might take home a 8souvenir0 of the event4 ,later1 these pieces had to be laboriously reassembled by scientists before any idea could be gained of the original shape and surface features of the meteorite4 ,even when thorough searches are made1 not all the meteorite fragments in the area of fall may be found for many months4 ,but if the people living in the region have been alerted and are on the lookout for unusual specimens or signs of meteoritic impact 7such as freshly made holes or 8craters0 in the ground1 shattered tree limbs1 and so forth71 the chances of ultimately finding many or most of the fallen masses are good4 ,as we have already mentioned1 numerous fragments of the ,norton meteorite 7including one weighing #acj pounds7 were found within two to three months after its fall on ,february #ah1 #aidh4 ,but the main mass was not discovered until the following ,august1 when a caterpillar tractor nearly tipped over into the large impact funnel that this huge stone had made in the earth4 ,fortunately1 field searchers from the ,institute had already talked to one of the farmers using the tractor and had told him that just such a 8crater0 might be found in the very area under cultivation4 ,consequently1 the crater was promptly reported4 ,in surveys concerned with the location and recovery of meteorites not seen to fall1 we find that sometimes meteorite fragments1 particularly the smaller ones1 lie on the surface of the ground or at shallow depth4 ,such fragments were probably too light to penetrate deep into the ground or1 in the years since their fall1 the action of rain1 wind1 and frost has uncovered them4 ,in such cases1 a party of searchers generally spreads out in order to get over as much ground as possible and each member of the group looks for meteorite specimens without using instrumental aids4 ,visual searches of this type have been very successful1 for example1 around the ,canyon ,diablo crater1 where almost the entire plain out to several miles from the rim once was sprinkled with large and small fragments of meteoritic nickel-iron4 ,this type of meteorite hunt is of only limited effectiveness because the specimens 7or at least a part of each one7 must be visible to the searchers4 ,illustration3 ,collecting small surface specimens of meteorites with portable detecting devices3 a powerful alnico magnet mounted on a light wooden sled1 and a horseshoe magnet at the end of a cane4 ,see p4 #ih4 ,to increase recoveries1 searchers have employed1 in addition to their eyes1 various types of permanent magnets1 either mounted on the end of a cane and used to probe the upper few inches of loose soil1 or dragged behind the searcher on a small1 light sled4 ,meteorite hunters have also used more powerful portable electromagnets to collect large amounts of meteoritic material 7both solid iron and iron-shale7 not only from the surface but also from shallow depths4 ,even the best of these simple magnetic devices1 however1 are useless in the detection of really deeply buried meteoritic material4 ,meteorites do not merely fall upon the earth 7as most astronomical textbooks still insist71 but usually penetrate into it--often quite deeply4 ,in fact1 one of our mathematical investigations showed that perhaps #ajj1jjj times as much meteoritic nickel-iron is concentrated below maximum plow-depth 7approximately one foot7 as lies above that depth4 ,clearly1 some form of instrument capable of detecting deeply buried meteorites needed to be devised if this wealth of buried material was not to be lost to science4 ,this need was answered by the development of special meteorite detectors4 ,although meteorite detectors working on several different principles have been constructed1 we shall limit attention here to the simplest and most field-worthy design4 ,the essential principle on which it operates is one familiar to any ,boy or ,girl ,scout who has used a magnetic compass4 ,the first lesson ,scoutmasters teach is not to read compass directions from such an instrument when it is held near a mass of iron of considerable size1 such as an automobile4 ,such a large iron mass alters or distorts the local magnetic field of the earth on which the direction-finding ability of the ordinary compass depends4 ,it is this very characteristic1 so bothersome to the user of a compass1 that is the principle on which meteorite detectors work4 ,for if an electrically driven meteorite detector capable of generating its own magnetic field is carried over a deeply buried iron meteorite1 the instrument's magnetic field will be distorted by the presence of the metal mass1 just as the local magnetic field of the earth was distorted by the metal of the automobile4 ,illustration3 ,a #adf-pound iron1 found by this girl without the use of instruments although only a small corner of the meteorite was visible above the surface of the ground4 ,illustration3 ,a commercially built meteorite detector in operation4 ,the operator of such a meteorite detector wears earphones and watches a signal needle in plain sight on the top panel of the detector4 ,since the phone and signal-needle circuits of the meteorite detector are in balance only when the magnetic field generated by the detector is undistorted1 the disturbing presence of a deeply buried meteorite is at once revealed by a shrill note sounding in the earphones and simultaneous motion of the signal needle4 ,if1 as in all buried treasure stories1 we use 8,x0 to stand for the spot where the signals from the detector are strongest1 then the meteorite-hunter has only to dig deep enough at 8,x0 to recover the celestial treasure-trove he is after4 #h4 ,,the ,,nature ,,of ,,meteors ,in answer to an exam question1 a freshman astronomy student wrote3 ,a meteor is the flash of light ,made by a falling meteorite ,as it rushes through the air in flight-- ,i hope to gosh this answer's right6 ,doggerel or not1 the student's definition correctly stated the true distinction between the two terms1 and the teacher marked his off-beat answer correct4 ,defined in more scientific terms1 a meteor is the streak of light 7usually of brief duration7 that accompanies the flight of a particle of matter from outer space through our atmosphere4 ,this particle may be as small as a tiny dust grain or as large as one of the minor planets which are called asteroids4 ,fortunately for the inhabitants of the earth1 most of the meteor-forming masses encountered by our globe are of the 8small-fry0 variety6 ,as the rapidly moving particle plunges earthward through denser and denser layers of atmosphere1 the air molecules offer ever-increasing resistance to its passage4 ,this resistance heats up the meteorite body until it glows4 ,technically speaking1 it becomes incandescent4 ,the meteor is this incandescence4 ,we see it as a darting point4 ,or as a ball of white1 orange1 bluish1 or reddish light4 ,but the material object that produced this light is the meteorite4 ,the distinction between these two terms--meteor and meteorite--we must emphasize again and again because people continue to use them incorrectly1 as1 for instance1 when they keep saying 8meteor crater0 instead of 8meteorite crater40 ,the majority of the meteors we observe represent the heat-induced 8evaporation0 of exceedingly small fragments of cosmic matter4 ,the smallest meteor-forming bodies reach the surface of the earth only as the finest of dust particles or as microscopic droplets of solidified meteorite melt4 ,these residues descend slowly through the atmosphere and may be carried for great distances4 ,afterwards1 they may be found scattered so widely and uniformly on the ground that their presence in any given locality cannot be accounted for by the fall of any specific meteorite4 ,this is a fact that1 for example1 one school of modern ,russian meteoriticists overlooked when they were dealing with tiny granules of meteoritic dust that had been recently found at ,podkamennaya ,tunguska4 ,these scientists tried to identify the tiny granules with the meteorite that had fallen there1 ,june #cj1 #aijh4 ,but the members of the latest 7#aieh7 ,russian expedition to that region about the impact point of #aijh clearly recognize the widespread character of meteoritic dust4 ,so they reject the theory that such dust found in the ,podkamennaya ,tunguska area is specifically connected with the meteorite that fell there a half century ago4 ,if sizable chunks of meteoritic material enter the atmosphere1 they may produce exceptionally large and brilliant meteors4 ,a spectacular meteor is generally known as a 8fireball0 if it is as bright as ,venus or ,jupiter4 ,it receives the ,french term bolide if1 in addition to showing great brilliance1 its flight is accompanied by detonations like the alarming sounds heard at the time of the ,ussuri and ,norton meteorite falls4 ,illustration3 ,,courtesy ,,of ,,university ,,of ,,new ,,mexico ,,press ,a bright ,giacobinid meteor1 photographed from a ,b-#bi during the shower of ,october #i1 #aidf4 ,see p4 #aae4 ,the term 8shooting star10 which is often applied to meteors1 in newspapers and magazine articles1 is a misnomer4 ,a meteor is not a distant sun 7that is1 a star7 in rapid motion1 for the whole path of the meteor lies close at hand within a restricted zone of the earth's atmosphere4 ,the word 8meteor0 comes from the ,greek word metera1 which once applied to any natural occurrence in the atmosphere--for example1 rainbows1 halos1 auroras1 and so forth4 ,nowadays1 the word 8meteor0 is used in a much more specialized sense than it was by the ancient ,greeks4 ,we have a specialized word1 meteoritics1 for the study of meteors and meteorites4 ,no one should confuse meteoritics with meteorology1 which is the science of things other than meteors and meteorites1 in the atmosphere--for example1 clouds1 storms1 air currents4 ,the region in which meteoric phenomena take place was long the subject of controversy4 ,some persons felt that meteors were nearby1 like lightning4 ,others said that they moved at the distances of the remote fixed stars4 ,this controversy on the whereabouts of meteors became heated1 although it could have been settled quickly by a simple experiment you can try out for yourself4 ,hold a pencil against the tip of your nose and look at it first with your right eye closed and then with your left eye closed4 ,repeat this experiment with the pencil held at arm's length4 ,in the first case1 the pencil will seem to shift position very greatly2 in the second1 although the same base line 7the distance between your eyes7 is used1 the pencil will seem to shift position only slightly4 ,such an apparent shift in position is called a parallactic displacement1 or1 simply1 parallax4 ,the notion of parallax is of the greatest importance in most branches of astronomy1 and it leads 7with proper instruments and a little mathematics7 to exact determinations of the distances of remote objects4 ,for our purpose1 we need not go into all the interesting but complicated details4 ,our experiment with the pencil shows that if a meteor was close by1 like a blinding bolt of lightning1 then1 as seen by a pair of observers separated by only a few blocks1 the meteor would show a large parallax4 ,but if this meteor was as far away as the stars1 it would show no parallax at all1 no matter how widely the pair of observers were separated on the earth4 ,there were many clever scientists among the ,greeks1 and it is quite possible that a pair of them actually tried out this simple parallax experiment on the meteors and so were able to prove that these beautiful light effects occurred in the high but not too distant layers of the atmosphere4 ,the earliest calculations of meteor heights that are so far known1 however1 were made in ,bologna1 ,italy1 in #agai and #agde--long after the heyday of ,greek science4 ,the meteor heights found by the ,italians were quite low in the atmosphere1 probably for two reasons4 ,first1 the visual 7unaided-eye7 observations they had to use were made by eyewitnesses stationed so close together that accurate fixes were impossible4 ,secondly1 these visual observations must have related only to the very brightest and therefore lowest portions of the luminous paths of the meteors through the atmosphere4 ,in #agih1 two ,german students operating from carefully chosen and widely separated stations began the systematic observation of meteors for parallax4 ,they found that the height of appearance of most meteors lay between #dh and #fj miles above the earth's surface4 ,it is now known that most meteors1 as observed with the naked eye1 appear at about #gj miles and disappear at about #ej miles above the surface of the earth4 ,these figures1 obtained from visual work1 still stand in spite of the development of such modern techniques as photographic and radar recording of meteor paths4 ,rarely1 meteors may appear at heights of #aej or more miles and fireballs may penetrate to within a few miles of the earth4 ,the average meteors1 however1 appear and disappear within a well-defined1 high-altitude zone in the atmosphere4 ,fortunately1 this atmospheric zone serves us as an effective shield against the constant bombardment of the smaller and much more numerous particles from outer space4 ,in earlier times1 scientists thought that the particles becoming visible as meteors must be tiny dense masses of iron or stone like the material composing the recovered meteorites4 ,most modern investigators1 however1 believe that the typical meteor-forming particles may be small loosely bound-together 8dust-balls02 that is1 fluffy clusters of matter held together by frozen cosmic vapors1 generally referred to simply as 8ices40 ,in any event1 these masses are usually very small1 ranging perhaps from the size of a pinhead to that of a marble4 ,because we cannot collect the tiny masses that are seen only as meteors1 it is impossible to determine their composition by ordinary laboratory methods4 ,the best we can do is to observe and record carefully the light these masses give off when they become incandescent in their plunge through the atmosphere4 ,we can examine this meteor light by using the spectroscope and spectrograph4 ,through these specially designed instruments we can make the meteor light reveal the chemical elements present in the incandescent masses4 ,each such element sends out light rays as characteristic of its nature as fingerprints are of the individual who made them4 ,photographs taken of these characteristic light rays are called spectrograms1 and what might be termed the 8fingerprints of light0 recorded on these spectrograms are known as spectra--which is the plural of the word spectrum4 ,if the source of light is a meteor1 the photograph shows a meteor spectrum4 ,from a study of a considerable number of good quality meteor spectra1 scientists have found that the principal elements in the masses responsible for meteors are iron1 calcium1 manganese1 magnesium1 chromium1 silicon1 nickel1 aluminum1 and sodium4 ,as we have already noted1 the resistance encountered by meteor-forming particles as they dash through our atmosphere is so great that they become incandescent and vaporize4 ,these small bodies must therefore be in very rapid motion4 ,before we attempt to find out the nature of the paths in space followed by meteorites1 we must take into account the fact that these bodies are observed from a station--the earth--which is itself in rapid motion4 ,you may have noticed that on a still day1 when rain drops fall vertically downward1 the streaks they leave on the windows of a swiftly moving car are not vertical but almost horizontal4 ,obviously1 it would be wrong to say the rain drops are falling from left to right or from right to left when they are actually falling almost straight down1 and it is only the forward motion of the car that makes them leave horizontal streaks4 ,illustration3 ,diagram showing meteorite moving along a 8closed0 7elliptic7 orbit1 e1 which intersects the earth's orbit1 ,e4 ,held by the gravitational attraction of the sun1 the meteorite is a permanent member of the ,solar ,system4 ,similarly1 neither the apparent speed nor the apparent direction of motion of a meteorite with respect to the moving earth is significant4 ,the important factor is the meteorite's velocity with respect to the sun at the time the meteorite is picked up by the earth4 ,illustration3 ,diagram showing meteorite moving across the earth's orbit1 ,e1 along an 8open0 7hyperbolic7 orbit1 h4 ,the meteorite is traveling at such high velocity that it will pass right through the ,solar ,system and back out into space unless it should chance to collide with the earth or another planet4 ,the sun1 however1 in any case is able to change materially the direction of motion of the transient visitor to our ,solar ,system4 ,this factor enables us to determine in which of two possible kinds of path the meteorite was moving before it was 8fielded10 as we might say in baseball1 by the earth4 ,this factor tells us whether the meteorite was moving about the sun in a relatively short1 closed1 oval-shaped path or1 instead1 was following an indefinitely long1 open path which began in the depths of space and would have returned there if the collision with the earth had not prevented4 ,either type of path is technically called an orbit4 ,the closed orbits are what the mathematicians term ellipses2 the open orbits1 hyperbolas4 ,to scientists1 the nature of the orbits followed by meteorites is most important1 especially in efforts to determine the mode and place of origin of these bodies4 ,to rocket engineers and astronauts1 it also matters a good deal whether the meteorites encountered on flights through space are traveling sedately along closed orbits about the sun or are zipping swiftly along open orbits4 ,the greater the speed of these cosmic 8hot-rods10 the more dangerous they are to space travelers4 ,for example1 a mere grain of nickel-iron moving at #dj miles per second is quite as lethal as a 4#ej-;caliber machine-gun slug1 which1 relatively speaking1 is traveling at only a snail's pace4 ,as our earth moves along its orbit about the sun1 meteoritic bodies can run into it from any direction4 ,the direction from which they do approach strongly influences the speed of these bodies as they plunge through the earth's atmosphere4 ,a meteorite moving slowly about the sun in the same direction as the earth and chancing to catch up with our globe more or less from behind will have an observed speed of only a few miles a second4 ,for example1 the speed calculated from ,harvard meteor-photographs of one such not-too-spectacular 8rear-end0 collision amounted to no more than #g4c miles per second1 just about the speed a rocket must acquire to escape from the apron strings of ,mother ,earth4 ,illustration3 ,meteor shower4 ,earth and particle-swarm passing through the intersection of their orbits at nearly the same moment4 ,in contrast to such a 8rear-end0 collision1 the speed observed would be far greater if the meteorite happened to collide exactly 8head-on0 with the earth4 ,for1 in this case1 the orbital speed of our planet would be added to that of the meteorite about the sun4 ,as an example1 suppose that at the earth's average distance from the center of our ,solar ,system1 the speed of a meteorite with respect to the sun were #cb4bc miles per second4 7,this speed was actually found for the mass that produced one of the first meteors photographed simultaneously by the ,harvard stations at ,cambridge and ,oak ,ridge1 ,massachusetts47 ,then if such a meteorite ran 8head-on0 into the earth1 the speed observed for it in the atmosphere would be over #ea miles per second4 ,and mathematics would show that the orbit of this meteorite with respect to the sun was a wide open hyperbola4 ,if the orbit of the earth and the orbit of a swarm of particles of cosmic matter intersect1 and if the earth and the swarm pass through this intersection in space at nearly the same moment1 multitudes of meteors appear4 ,we then say that a meteor shower takes place4 ,the position of the point at which the particle-swarm crosses the earth's orbit about the sun fixes the date of the meteor shower4 ,because the particles that make a meteor shower are moving through space along parallel paths as they come into the earth's atmosphere1 the meteors all seem to shoot out from a single small area in the sky4 ,you may have seen something like this in the case of the sunrise or sunset effect known as 8the sun drawing water40 ,in this more familiar phenomenon1 the sun's disk is the area from which shafts of sunlight radiate out in a beautiful1 if somewhat irregular1 fan-like pattern4 ,the area from which the meteors of a given shower seem to come is the radiant of that shower4 ,meteor showers are named for the constellation in which their radiant lies4 ,the suffix 8-id0 7,greek for 8daughters of071 or some modification of this suffix1 is added to the name of the constellation from which the meteors seem to radiate4 ,the ,orionid radiant1 for example1 is in ,orion1 the ,hunter2 the ,leonid radiant is in ,leo1 the ,lion2 and the ,lyrid radiant is in ,lyra1 the ,harp4 ,exceptions to this rule do occur1 however4 ,astronomers may refer to a shower sometimes appearing on the night of ,october #i as the 8,giacobinid0 shower in honor of the comet ,giacobini-,zinner1 which is associated with this particle-swarm4 ,illustration3 ,radiant of a meteor shower4 ,generally not a point but a small area1 here intentionally exaggerated in size4 ,solid arrows represent plotted paths of observed meteors4 ,by extending these paths backwards1 observer can determine the radiant4 ,in the course of each year1 the earth passes through a number of particle-swarms of varying densities4 ,some of the resulting meteor showers1 like the ,leonids and ,giacobinids1 are very feeble in most years1 but sometimes produce spectacular displays4 ,the more important recognized meteor showers are3 ,,name ,,of ,,shower ,,date ,,of ,,maximum ,quadrantids ,january #a-c ,lyrids ,april #ba ,eta-,aquarids ,may #d-f ,perseids ,august #aj-ad ,giacobinids 7,nu-,draconids7 ,october #i ,orionids ,october #bj-bc ,leonids ,november #af-ag ,geminids ,december #ab-ac ,certain daytime streams are also known to be active during ,june and ,july4 ,these daytime showers are1 of course1 invisible in the glare of sunlight1 but they can be picked up by radar devices like those used in ,world ,war ,,ii to spot enemy airplanes4 ,some meteor showers have been splendid enough to make a place for themselves in the historical record4 ,examples are the ,leonid returns of #ahcc and #ahff1 and the ,giacobinid showers of #aicc and #aidf4 ,during these displays1 meteors fell in a veritable fiery snowstorm1 several hundred meteors sometimes appearing within a minute4 ,not every annual return of a meteor shower is spectacular1 however1 since conditions may not be favorable each year for a brilliant display4 ,after all1 both parties to a traffic collision at an intersection must try to pass through the intersection at the same time4 ,our earth1 like a well-managed train1 always goes through the intersection on schedule1 but the particles responsible for meteor showers are much more erratic4 ,they may be early or late--or they may not show up at all4 ,of the meteor showers seen annually1 the ,perseids are the most dependable4 ,the ,leonids put on their best shows at intervals of #cc years 7#agii-ahjj1 #ahcb-cc1 #ahff1 etc474 ,the ,giacobinids at intervals of #f years 7#aicc1 strong2 #aici-dj1 poor2 #aidf1 magnificent74 ,if you plan to observe a meteor shower1 here are some suggestions4 ,you will need3 ,acquaintance with the stars1 both faint and bright1 in the region containing the radiant of the shower4 ,comfortable reclining lawn-chair4 ,warm clothing 7including blankets7 for winter showers or summer ones at high elevations4 ,a patient family that will not only approve of your observing but will help you get up to watch after midnight1 when most showers are at their best4 ,a corner of your back yard 7or sun roof7 where you can shade your eyes from street lights and other illumination4 ,timepiece1 preferably with radiant dial4 ,sit back and watch ,nature put on her show4 ,any records you make may have some scientific value even if you note only these two things3 ,hourly number of meteors seen4 ,condition of the sky 7clear1 hazy1 cloudy1 etc47 during each hour of your watch4#f ,at present1 we know of only one instance in which it seems probable that a meteorite came to earth during a meteor shower4 ,the ,mazapil1 ,mexico1 iron meteorite fell at #i3jj p4m4 on ,november #bg1 #ahhe1 during a return of the now very weak ,bielid meteor shower4 ,scientists still cannot decide whether or not a mere coincidence was involved in this case4 ,as we have already mentioned1 most of the cosmic particles rushing into our atmosphere evaporate and do not reach the earth at all except as the tiny congealed droplets and spherules of their own melt4 ,some cosmic particles1 the micro-meteorites1 are so tiny that they 8stall0 rather than fall down4 ,these minute objects do not melt or disintegrate and so preserve their original cosmic form unchanged4 ,scientists have developed various methods for the collection of both of these types of material in order that at least rough estimates of their rate of accumulation on the earth can be made4 ,one of the simplest methods of collecting this so-called 8meteoritic dust0 is to expose a sticky glycerine-coated glass microscope slide for at least a #bd-;hour period in a protected spot well away from locations where any industrial contamination is in the air4 ,at the end of the period of exposure1 the 8catch0 on the slide is examined microscopically1 and the individual trapped particles are counted and classified4 ,meteoritic dust is also carried down to the ground by rain1 snow1 and hail and can therefore be obtained by filtering rainwater or melted glacier-ice1 snow1 and hail4 ,such collection efforts have been plagued by the difficulty of identifying the particles4 ,how can a collector be sure that the dust he has trapped1 even though magnetic and possibly even in part metallic1 does not come from some smelter or other industrial plant8 ,because of such uncertainties1 the current estimates of the annual deposit of meteoritic dust for the world range from approximately #bj tons to several million tons4 ,we need improved collection and identification techniques if we are to obtain trustworthy figures4 ,recent analyses of rainfall records indicate that the infall of meteoritic dust produces at least one interesting weather-effect4 ,these analyses show that rainfall peaks often occur some #cj days after the appearance of important meteor showers4 ,apparently1 as meteoritic dust particles from the meteor showers filter down through the cloud systems in the lower layers of the atmosphere1 the individual particles serve as centers about which atmospheric moisture condenses to form raindrops4 ,the time lag of approximately a month is considered to be due to the very slow rate of fall of such tiny particles4 ,it looks very much as if ,mother ,nature had beaten man to the idea of 8seeding0 the clouds to produce rainfall6 #i4 ,,the ,,nature ,,of ,,meteorites ,so far in this book we have dealt with meteorites indirectly1 chiefly in connection with their fall1 distribution1 and recovery4 ,in this chapter1 however1 we are shifting our attention to the meteorites themselves1 and will tell what the main types of meteorites are1 what meteorites are made of1 what they look like1 and how to tell them from ordinary rocks4 ,first of all1 meteorites neither all look alike nor have the same composition4 ,the general term 8meteorite0 applies to any mass that reaches the earth from space4 ,such masses are made up of metals and minerals in varying proportions4 ,the term 8meteorite0 is nearly as general in meaning as the word 8rock10 which geologists apply to bodies1 large and small1 that are formed by earth processes and are composed of various kinds of minerals4 ,actually1 there are almost as many different kinds of meteorites as there are kinds of rocks2 so you can see that in meteorites a wide range of composition and appearance is possible4 ,all recognized meteorites belong to one of three main divisions1#g irons1 stones1 and stony-irons4 ,the irons are composed of an alloy of iron and nickel which may contain small inclusions of nonmetallic minerals4 ,illustration3 ,internal structure revealed when the 8etching0 process is applied to that type of meteorite known as a 8granular hexahedrite40 ,see p4 #abj4 ,after a cut section of an iron meteorite has been polished1 the flat surface1 except for possible inclusions1 is mirror-like and resembles stainless steel4 ,it appears to be remarkably uniform and uninteresting1 but this appearance is misleading4 ,a characteristic and beautiful structural pattern develops when such a polished nickel-iron surface is treated with1 for example1 a special mixture of nitric acid1 alcohol1 and ,arabol glue4 ,this process of treatment is known as 8etching40 ,the different structural patterns brought out by such etching give us the basis for classifying the iron meteorites4 ,if the etching process reveals certain features from which we can infer a cubic1 or #f-;faced1 crystalline structure1 we classify the iron meteorite as a hexahedrite4 ,if etching produces a certain special pattern from which we can infer an #h-;faced1 or octahedral1 crystalline structure1 we recognize the second subdivision of iron meteorites3 the octahedrites4 ,this remarkable pattern was discovered and first described by ,alois von ,widmansttten1 of ,vienna1 in #ahjh4 ,the third subdivision of iron meteorites consists of the 8structureless0 ataxites4 7,from the ,greek for 8without arrangement407 ,on an ataxite1 etching brings out only a finely granular pattern with a stippled appearance4 ,the stones are composed chiefly of minerals that are combinations of various elements with silicon and oxygen--for example1 olivine 7,mg1 ,fe7,si,o4 ,meteorites belonging to this division also contain combinations of elements with oxygen--such as magnesium oxide 7,mg,o7 and aluminum oxide 7,al,o74 ,usually1 the stony groundmass contains scattered specks1 grains1 and thin veins of the same shiny nickel-iron alloy that makes up the iron meteorites almost in their entirety4 ,illustration3 ,a4 ,,brezina ,e4 ,,cohen ,,photo ,widmansttten pattern which emerges when the carefully polished surface of that type of iron meteorite technically known as a 8fine octahedrite0 is 8etched40 ,the stony-irons1 as the name indicates1 are an 8in-between0 division4 ,some of the stony-irons1 called pallasites1 are sponge-like but rigid networks of nickel-iron alloy in which the smoothly rounded openings in the sponge enclose small gemlike masses of olivine4 ,a cut and polished section of a pallasite showing round and oval gems of yellow-green olivine set in a silvery mesh of nickel-iron is a beautiful museum specimen indeed6 ,in the silicate-siderites1 another type of stony-iron1 a nickel-iron matrix is studded with angular fragments1 shreds1 and splinters of silicate minerals of all sizes4 ,in the photograph1 we can see that each of the various areas of the nickel-iron matrix 7lighter in color7 exhibits its own distinct crystallographic orientation1 as is clearly indicated by the different ,widmansttten patterns4 ,even a hasty comparison of polished sections of silicate-siderites and pallasites will leave no doubt that two quite distinct modes of formation were required to produce stony-irons of such different types4 ,meteoritic nickel-iron has the following average chemical composition4 ,to the nearest tenth1 this alloy contains3 ,iron 7,fe71 #ij4i2 nickel 7,ni71 #h4e2 cobalt 7,co71 #j4f4 ,this alloy gave scientists the key to the development of commercial stainless steels4 ,it may also contain small amounts of phosphorous1 sulfur1 copper1 chromium1 and carbon4 ,the average chemical composition of stony meteoritic material is somewhat more complicated4 ,to the nearest tenth1 the 8stones0 contain3 oxygen 7,o71 #da4j2 silicon 7,si71 #ba4j2 iron 7,fe71 #ae4e2 magnesium 7,mg71 #ad4c2 aluminum 7,al71 #a4f2 calcium 7,ca71 #a4h2 sulfur 7,s71 #a4h4 ,the stony material may also contain smaller percentages of nickel1 cobalt1 copper1 carbon1 chromium1 and titanium4 ,illustration3 ,a4 ,,brezina ,e4 ,,cohen ,,photo ,enlarged section of a stony-iron meteorite showing rounded olivine grains 7dark in color7 set in a network of nickel-iron alloy 7light in color74 ,illustration3 ,a4 ,,brezina ,e4 ,,cohen ,,photo ,polished and etched section of a silicate-siderite showing angular fragments of silicate minerals 7dark in color7 imbedded in a metallic matrix4 ,in the stony-iron meteorites1 we analyze the nickel-iron and stony portions separately4 ,on the average1 each of these portions has about the chemical composition that is given for it above4 ,mineralogists have identified a variety of familiar minerals in meteorites4 ,these include olivine1 the plagioclase feldspars1 magnetite1 quartz1 chromite1 and1 rarely1 microscopic diamonds4 ,all of these minerals are found here on earth in such igneous rocks as basalts and peridotites4 ,on the other hand1 the meteoritic nickel-iron alloys 7kamacite1 taenite1 and plessite1 for example7 and such meteoritic minerals as schreibersite 7nickel-iron phosphide7 and daubreelite 7iron chromium sulfide7 do not occur naturally on the earth4 ,we should stress here that although unusual combinations of known elements are present in meteorites1 no new elements have been discovered during the increasingly intensive study of these masses during the last #aej years4 ,the majority of stony meteorites show a structure not found in terrestrial rocks4 ,these meteorites are made up of rounded1 shot-like bodies called chondrules 7from the ,greek word for 8grain074 ,the individual chondrules may vary in size from those as large or even larger than a walnut down to dust-sized grains4 ,the most common size is about that of peppercorns4 ,the chondrules are often composed of the same material as the groundmass in which they are imbedded and unless the meteorite containing them is a very fragile one1 they will break with the rest of the mass1 as will sand grains in a quartzite4 ,if the meteorite is fragile1 however1 the individual chondrules can generally be broken out whole4 ,meteorites containing chondrules are called chondrites4 ,illustration3 ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,microphotograph of a thin section of a chondrite1 showing the circular1 or nearly circular1 cross sections of a number of chondrules1 including one of large size at the upper edge of the section4 ,a small percentage of stony meteorites have no chondrules4 ,these meteorites are known as achondrites 7meaning 8not chondrites07 and they resemble terrestrial rocks more closely than the chondrites do4 ,some achondrites contain almost no trace whatever of metal1 although in others 7for example1 the ,norton ,county meteorite1 of ,chapter #b7 small lumps and specks of nickel-iron are sparsely distributed through the stony groundmass4 ,meteorites are as variable in shape as they are in composition and structure4 ,many are cone-shaped2 others shield-1 bell-1 or ring-shaped2 still others pear-shaped4 ,one iron fragment recently recovered from the ,glorieta1 ,new ,mexico1 fall has been described as 8macro-spicular10 meaning needle-shaped on a very large scale4 ,the photographs opposite illustrate a number of the commoner forms known4 ,the ,glorieta specimen has been nicknamed 8,alley ,oop's shillelagh10 for only a person of great strength could wield this #ac-pounder with ease6 ,in general1 the shape of meteorites depends upon the amount of mass lost by 8evaporation0 during passage through the earth's atmosphere4 ,this factor1 in turn1 depends not only upon the speed of transit1 but also on such physical characteristics of the meteorite as its tensile strength and whether or not it contains certain alloys and minerals that vaporize more easily than the rest of the meteorite4 ,the ring-shape of the ,tucson1 ,arizona1 iron is believed to have resulted from the 8melting away0 of a huge inclusion of stony material during the descent of the meteorite4 ,illustration3 ,,chicago ,,museum ,,of ,,natural ,,history ,,photos 7,,bottom ,,right7 ,,institute ,,of ,,meteoritics ,,photo ,a few of the many shapes exhibited by meteorites3 ring-shaped1 perforated and highly irregular1 pear-shaped1 jaw shaped1 needle-shaped4 ,when meteorites are recovered and taken to the laboratory for study1 one of the first things scientists do is to weigh them4 ,if a meteorite is very large1 special scales sometimes have to be constructed for this purpose4 ,such was the case for the largest meteorite so far weighed3 the giant ,ahnighito1 ,greenland1 meteorite1 which ,peary brought to ,new ,york ,city by ship4 7,see ,chapter #c47 ,a specially constructed scale on which this huge mass is now mounted gives for its weight about #fh1jjj pounds4 ,other meteorites famous for their great size are3 the ,bacubirito1 ,mexico1 #bg tons2 ,willamette1 ,oregon1 #ad tons2 ,morito1 ,mexico1 #aa tons2 and the ,bendego1 ,brazil1 #e tons4 ,all of these are irons4 ,the largest stone meteorite so far recovered as one mass is the so-called ,furnas ,county1 ,nebraska1 stone1 which is the principal fragment of the ,norton1 ,kansas1 fall1 and weighs about #b1cfj pounds4 ,at the other end of the size-range1 investigators have recovered meteoritic masses weighing no more than a small fraction of a gram4 ,from a stone shower that occurred at ,holbrook1 ,arizona1 field searchers have found some of the very smallest specimens in anthills4 ,the insects had carried these tiny meteorites along with sand and garnet grains in building their hills6 ,illustration3 ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,the ,willamette iron1 famous for its great size and weight 7#ad tons71 on exhibit at the ,hayden ,planetarium1 ,new ,york ,city4 ,see pp4 #cf1 #ci4 ,the only sure way to determine whether or not an object is a meteorite is to have a small piece of it 7say1 a fragment the size of an egg7 tested chemically and microscopically by an expert on meteorites4 ,nevertheless1 there are several questions whose answers will help you to decide whether or not you are on the right track in suspecting that a 8rock0 you have found may be a meteorite3 ,is your specimen especially heavy8 ,does your specimen show a thin blackish or brownish crust on its outer surface8 ,does your 8rock0 have shallow1 oval pits on its outer surface8 ,if the specimen has a corner knocked off1 do you see specks and grains of metal on the broken surface8 ,is your specimen especially heavy8 ,the iron and stony-iron meteorites are very heavy4 ,a #a-;inch cube of iron meteorite weighs approximately #h times as much as a #a-;inch cube of ice4 ,even the stones1 which are only about half as dense as the irons1 are much heavier than ordinary rocks4 ,does your specimen show a thin blackish or brownish crust on its outer surfaces8 ,you will recall that specimens of both the ,ussuri and ,norton meteorites showed a 8glaze0 of fused material which we call fusion crust4 ,most freshly-fallen meteorites are covered with such a crust4 ,to illustrate how this crust forms1 consider a snowball that you bravely hold in your freezing hand until the outer surface melts4 ,if you then were to leave the snowball outside overnight1 the melted outer surface would freeze into a hard crust4 ,illustration3 ,piezoglyphs 7oval pits resembling thumb-prints7 in a stone meteorite1 found at ,belly ,river1 ,canada4 ,see p4 #acb4 ,in similar fashion1 the surface of a meteorite melts during the blazing-hot part of its flight through the air1 only to 8freeze0 into a hard1 firm coating in the lower1 cooler portions of its path4 ,this hardened coating1 the fusion crust1 is of much importance4 ,its presence is one of the best indications that a 8rock0 is really a meteorite4 ,from the character of the fusion crust1 experts can piece together a good deal about what happened to a meteorite on its way down to earth4 ,if you should be lucky enough to find a meteorite1 don't break off the fusion crust4 ,a whole encrusted specimen in the hand is worth #bjj crustless fragments scattered at your feet6 ,does your 8rock0 have shallow1 oval pits or depressions on its outer surface8 ,such features are known technically as piezoglyphs 7,greek piezein1 to press glyph1 to carve7 and popularly as 8thumb-prints40 ,they were formed during the meteorite's flight through the atmosphere when the softer portions of its outer shell were 8eroded0 away1 leaving small scooped-out places4 ,these pittings are very similar to the prints that would be made by the human hand in a lump of modeling clay or bread dough4 ,in one case1 they gave rise to the false idea that the meteorite had fallen in a plastic state and that the imprints had been formed when its finders first pulled the mass out of the ground by hand4 ,if the specimen you have found already has a corner knocked off1 do you see specks and grains of metal on the broken surface8 ,such scattered bits of nickel-iron 7not to be confused with the shiny mica flakes often seen in igneous rocks7 characteristically occur in the grayish or brownish groundmass of stony meteorites4 ,if your specimen is unbroken1 hold it lightly against a spinning carborundum wheel or use a file to grind a small flat surface upon it1 and then examine this surface for specks of metal4 ,if the answers to these questions are yes1 then there is a good possibility that you have found a genuine meteorite4 ,if meteorites remain buried in the ground for a long period of time1 their characteristic surface-features may weather away4 ,under such conditions1 iron meteorites develop heavy-layered coatings of rust 7iron oxide7 as much as several inches in thickness4 ,if irons stay in the ground long enough1 they may rust away almost completely and turn into shale balls1 like those found near the ancient ,wolf ,creek1 ,australia meteorite crater4 7,see ,chapter #d47 ,stone meteorites buried in the ground for any great length of time may disintegrate and become completely unrecognizable as meteorites4 ,the fact that meteorites of all kinds are attacked by weathering has always argued strongly in favor of their prompt recovery4 ,in the case of witnessed falls1 prompt recovery is even more important1 for only thus can specimens still retaining measurable amounts of various short-lived radioactivities be made available to physicists eager to investigate them with the most modern radiometric equipment4 #aj4 ,,tektites1 ,,impactites 8,,fossil0 ,,meteorites ,before southern ,australia was occupied by the white man1 the native tribesmen of that region treasured certain small rounded pieces of black glass as medicine stones1 rainmaking stones1 and message stones4 ,the ,wadikali tribe referred to these objects as mindjimindjilpara1 a word meaning 8eyes that look at you like a man staring hard40 ,the early ,european settlers of the area called the same black glassy masses 8blackfellows' buttons40 ,both phrases applied to objects that modern scientists call 8australites10 which are now one of the best known types of tektites 7,greek3 tktos1 molten74 ,these ,australian tektites and the tektites from many other countries around the world are a problem to meteoriticists4 ,the question is1 are they really meteorites8 ,many investigators believe that the answer is yes1 and they are inclined to add to the three main divisions of true meteorites listed in the preceding chapter1 a fourth3 the tektites4 ,these mysterious glassy objects occur in such widely separated localities as ,czechoslovakia1 the ,philippine ,islands1 ,borneo1 the ,ivory ,coast of ,africa1 ,australia1 ,indo-,china1 ,texas1 ,malaya1 and ,java4 ,in these and still other areas1 they have been found by the thousands in surface deposits of sand1 clay1 and gravel4 ,illustration3 7left7 8,flanged buttons0 from ,australia4 7right7 ,several sizes of 8dumbbells0 from ,australia4 ,see p4 #acf4 ,tektites have never been seen to fall4 ,in spite of this fact1 as we noted above1 a number of scientists believe that1 like the meteorites1 the tektites really did come from outer space but1 that they fell to earth before man was here to see them come down--or at least before he had acquired the means and skill to make lasting records of such an occurrence4 ,tektites are usually quite small1 weighing between #a and #ajj grams1 although a few of much larger size have been found4 ,one large specimen from the ,philippines weighed about pound4 ,two giant tektites1 one weighing pound and the other over #a pound1 are in the collection of the ,british ,museum4 ,in composition1 tektites are an impure silica-glass containing low percentages of the oxides of such elements as iron1 magnesium1 calcium1 and titanium4 ,if tektite fragments are held under a lamp and observed by reflected light1 their thicker parts generally appear to be jet-black4 ,if1 however1 these same specimens are held up between the observer and the light1 then their thin razor-sharp edges are seen to be bottle-green1 yellow-green1 brownish1 or even colorless4 ,in shape1 many tektites are roundish or oval4 ,others are shaped like dumbbells1 ladles1 canoes1 and teardrops4 ,so they are known by those descriptive terms4 ,one particularly interesting example is the unusual 8flanged button0 of ,australia4 ,tektites of this type look like miniature ,south ,american gold-pans1 the bateas1 heaped high with pay dirt4 ,australian gold-field workers regarded these tektites as magical1 and used them as good-luck charms4 ,superstitious ,american gold-seekers brought them into the ,united ,states all the way from ,australia6 ,illustration3 7above7 ,rounded tektite from ,texas4 7below7 ,deeply grooved bediasite from ,texas4 ,some tektites 7for example1 many of the 8bediasites0 from ,texas7 are deeply grooved and channeled1 and have a very jagged and irregular appearance4 ,even the smoother tektite surfaces are characterized by flow lines1 flow ridges1 and bubble pits4 ,many weathered pebbles and fragments of obsidian somewhat resemble the tektites superficially4 ,there is a very simple test by which you can distinguish true tektites from obsidian4 ,if you hold a thin splinter of tektite glass in a blowpipe flame1 the glass melts quietly but only with the greatest difficulty4 ,on the contrary1 when you test in the same flame the terrestrial glass1 obsidian1 it froths up much more easily1 into a bubbly1 whitish mass4 ,although the question of where the tektites came from is still not entirely settled1 most scientists agree that all tektites did have a common origin4 ,for example1 tektites from widely scattered localities on the earth's surface show not only similar queer shapes and surface markings 7technically known as 8sculpturing071 but also have very much the same chemical composition and1 in particular1 the same content of radioactive elements4 ,because the tektites chemically resemble certain terrestrial rocks1 scientists at first believed that some kind of earth process must have created them4 ,one suggestion was that lightning had fused dust particles suspended in the air to form them2 another1 that they had come from volcanoes2 still another1 that the tektites were simply inclusions that had weathered out of terrestrial rocks4 ,a few scientists once took seriously the possibility that tektites were refuse from primitive glass factories6 ,illustration3 ,tektite vs4 obsidian1 after blowpipe test4 ,while such theories have not yet been completely discarded1 most scientists now feel that the tektites had their origin somewhere outside the earth4 ,there are several reasons for this belief4 ,first1 the shape of such unusually symmetrical forms as are found1 for example1 among the australites1 indicates that these small bodies at one time were members of a swarm of freely-spinning liquid masses4 ,again1 flow features observed on the surfaces of certain tektites 7and the fusion crust definitely identified on one specimen7 show that these bodies at some time must have traveled through the earth's atmosphere at high velocity4 ,if1 then1 the tektites were not produced by earth processes1 where did they come from8 ,according to primitive legends1 they were 8rocks0 or 8pebbles0 from the moon4 ,indeed1 one of the earliest scientific theories as to their origin 7proposed by the ,dutch authority ,verbeek in #ahig7 likewise attributes them to debris jetted out from the moon4 ,another holds that tektites are fragments of the outermost glassy layers of some so-called 8meteorite-planet10 or planets4#h ,still another idea is that tektites are what is left of a comet when it passes so close to the blazing-hot sun that the 8ices0 which make up most of the cometary nucleus 7head7 are all distilled away4 ,these theories of the origin of the tektites are based primarily on their observed shapes1 surface features1 and compositions4 ,the senior author of this book has suggested still another possible theory based on the very unusual nature of the observed distribution of the tektites on the face of the earth4 ,to explain this theory1 we first recall that the planet on which we live is more nearly a true sphere than are such familiar 8spherical0 objects as baseballs or basketballs4 ,consequently1 any plane through the center of the earth cuts its surface in a curve that to all intents and purposes is what geometers refer to as a great circle4 ,illustration3 ,every plane passing through the center of a sphere intersects the surface in a great circle4 ,in this figure1 only the front half of the great circle cut out by the plane is shown4 ,now the significant fact is that all the tektite deposits known at present are located on or very near to three great circles on the earth's surface4 ,mathematics shows that if some earth process had created the tektites at random over the surface of the earth1 then the odds would be very strongly against the existence of this peculiar 8great-circle distribution40 ,but such distribution along great circles would be expected if the tektites had resulted from what might be likened to 8chain-falls0 upon the earth of objects like nearby satellites moving in orbits encircling our globe4 ,this notion brings up the interesting possibility that at some time in the remote past1 the earth may have been the proud possessor of a set of equatorial rings4 ,these rings would have been similar to those at present circling in the plane of ,saturn's equator4 7,jupiter1 too1 may once have had its own set of equatorial rings47 ,the rings of ,saturn are known to be made up of countless very small meteorites4 ,in the same way1 the 8earth rings0 of prehistory could have consisted of swarms of tiny nearby meteoritic satellites--the tektites--moving about the earth in the plane of its then-existing equator4 ,eventually1 the innermost of these small natural satellites collapsed onto the earth's surface1 falling along the old equator4 ,at least twice thereafter1 this process was repeated1 the points of impact of the later tektite falls again lining up along whatever great circle of the earth happened to be the equator at the time of fall4 ,as the geologists and other investigators have shown1 major shifts have occurred in the position of the earth's equator during past geologic ages4 ,this fact is well-substantiated by discoveries of fossil shells and plants on the cold ,antarctic continent and of glacial deposits in hot ,south ,africa4 ,therefore1 we could hardly expect the tektite deposits1 which are believed to have fallen at widely separated intervals of time1 to have all occurred along a single great circle on the earth's surface4 ,as you can see1 the so-called 8tektite-puzzle0 is a complex one4 ,as if this were not bad enough1 ,mother ,nature has added to the confusion by creating in addition to the tektites another type of silica-glass not only found along the very same three great circles sprinkled with true tektites1 but also having other features in common with the tektite glasses4 ,at ,mount ,darwin in ,tasmania and at ,wabar in the ,rub' al ,khali desert of ,arabia1 large and small fragments of this curious silica-glass have been collected4 ,at ,wabar the masses of silica-glass were found in and about the rims of a series of meteorite craters formed in nearly pure sand1 as we pointed out in ,chapter #d4 ,these meteorite craters are known to have resulted from the high-speed impact of iron meteorites upon the sand dunes of the ,wabar site4 ,since the silica-glasses of ,wabar have been found to contain countless spherules of nickel-iron of the same composition as the iron meteorites discovered about the ,wabar meteorite craters1 it seems quite certain that both the sand of the earth target and the nickel-iron of the falling meteorites were vaporized by the intense heat generated at impact4 ,consequently1 it is natural that these ,wabar masses of congealed silica-glass and nickel-iron be called impactites4 ,they are silica-glasses1 created chiefly from terrestrial materials by the impact of large crater-forming meteorites4 ,this same name is now applied to all silica-glasses believed to have the same origin as those at ,wabar4 ,as regards size if not composition1 the crater-forming meteorites responsible for the ,wabar and other impactites may have been big brothers of the small-fry responsible for the showers of true tektites4 ,or these big ones may have moved about the earth in orbits distinct from those followed by the tektite swarms but lying in the same plane as one of these swarms4 ,in addition to the curious puzzle of the tektites1 meteoriticists have also run up against the problem of 8fossil0 meteorites or1 more exactly1 the problem of the lack of 8fossil0 meteorites4 ,as we have already mentioned1 no positively identified meteorite has ever been found in other than the most recent rock layers4 ,with all the mining--particularly coal mining--that has gone on throughout the world in historic times1 this fact does seem astonishing4 ,a number of explanations can be suggested for this absence of ancient meteorites4 ,in the geologic past1 meteorite falls may not have occurred as often as they do today4 ,for example1 the primeval atmosphere of the earth may have been so much denser than at present that even quite large meteorites were totally vaporized as they passed through it and therefore never reached the ground4 ,again1 even if the rate of infall of meteorites was the same in the remote past as now1 still various weathering processes active ever since the earliest meteorites fell may have so changed them in appearance and composition that they are no longer recognizable for what they are4 ,several unusual lumps of rock from ,england and a mass of iron from ,austria1 all found at some depth by coal miners1 have been tentatively put forward as 8fossil0 meteorites4 ,but studies of these masses have so far produced no conclusive results4 ,still1 we should not ignore the possibility that someday meteorites may be found and identified in rocks of considerable age4 ,illustration3 ,l4 ,j4 ,,spencer ,,photo ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,mysterious glass objects found in the ,libyan ,desert4 7right7 ,cut and polished specimens4 ,does it seem as if we have posed more problems than we have solved in this chapter8 ,it is very true that we have done just that4 ,in speaking briefly about the tektites1 the impactites1 and the absence of 8fossil0 meteorites1 we have by no means tried to present the last word on the troublesome but highly interesting problems connected with these objects--problems that admittedly may take scientists years or even decades of further research to solve4 ,perhaps you will find here the kind of unusual and thought-provoking problems that make the study of meteorites a rather special challenge4 ,if so1 you may wish to take an active part someday in unraveling these puzzles4 #aa4 ,,omens ,,and ,,fantasies ,men seem to have always taken an interest in meteorites1 but not until the early nineteenth century were these objects considered to be worth preserving for scientific study4 ,in the beginning1 people believed that because meteorites fell from the heavens1 they were either gods themselves or messengers from the gods4 ,the more civilized of early men therefore carefully kept the fallen meteorites4 ,they draped them in costly linens and anointed them with oil4 ,in many instances1 the people built special temples in which meteorites were actually worshipped4 ,some of the holy stones of the ancients1 such as the ,diana of the ,ephesians1 mentioned in the ,bible as 8the image which fell down from ,jupiter10#i are now thought to have been meteorites4 ,meteorite worship was common long ago in the ,mediterranean area and in ,africa1 ,india1 ,japan1 and ,mexico4 ,this practice still persists in some regions even in modern times4 ,the ,black ,stone of the ,kaaba1 for example1 has been sacred to all ,mohammedans from about #gjj ,a4,d4 right up to the present4 ,it is said to be a meteorite although this fact has never been verified1 because strict religious taboos connected with the stone prevent any scientific examination or study of it4 ,on the contrary1 the ,andhra1 ,india1 meteorite is known to be a genuine one4 ,the story of the fall and preservation of this meteorite provides a fairly modern example of practices rooted in the ritual and custom of far more ancient times4 ,at about #d3jj in the afternoon of ,december #b1 #ahhj1 the people of ,andhra heard a noise like that made by a gun4 ,some of the villagers saw a 8dark ball0 come to earth in a field near them4 ,this falling object sent up a small cloud of dust as it struck the ground4 ,after the stone had been recovered from the field and the dust had been washed from its surface1 two ,brahmin priests took charge of it and began to collect money for the erection of a temple in which the holy object could be properly displayed4 ,the scientist who promptly investigated the ,andhra fall reported that throngs of worshippers were crowding into the as yet unfinished brick temple to make offerings of flowers1 sweetmeats1 milk1 rice1 water1 bel leaves1 and of course money4 ,the stone had been named ,adbhuta-,nth1 8the miraculous god40 ,it was shaped like a round loaf of blackish bread and weighed an estimated #f pounds4 ,the scientist was not allowed to touch it1 but he got close enough to verify that the stone was a meteorite covered with a typical blackish fusion crust4 ,not only has man worshipped meteorites1 but during a period extending from approximately #cjj ,b4,c4 to #cjj ,a4,d41 emperors and self-governing cities frequently marked the fall of meteorites by minting special coins or medals known as betyls4#aj ,one of these is the betyl of ,emisa1 ,syria1 made by ,antonius ,pius 7#ach-afa ,a4,d474 ,the historian1 ,herodotus1 accurately described the object honored by this betyl as3 8,a large stone1 which on the lower side is round1 and above runs gradually to a point4 ,it has nearly the form of a cone1 and is of a black color4 ,people say of it in earnest that it fell from ,heaven40 ,the stone is shown on the coin as carried on a quadriga 7a carriage drawn by four horses7 under a canopy of four sunshades4 ,illustration3 ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,drawing of multiple fireball1 over ,athens1 ,october #ah1 #ahfc4 ,j4 ,f4 ,j4 ,schmidt1 the celebrated pioneer fireball observer1 described it as a mass of dazzling light 8bringing into view land and sea1 with the ,acropolis and the ,parthenon a mile away across the city40 ,many ancient peoples held meteorites in great reverence1 particularly if they were seen to fall4 ,but at the same time1 other more practical-minded individuals made good use of the durable and easily worked alloy provided by nature in the nickel-iron meteorites4 ,this alloy was frequently used to make ax-heads1 spear and harpoon points1 knives1 farming tools1 stirrups and spurs1 and even pots and other utensils4 ,archeologists have found earrings and similar ornaments overlaid with thin sheets of hammered meteoritic iron in ,indian mounds of the ,ohio ,valley4 ,they have also discovered round beads made of nickel-iron in ,indian mounds of the ,havana1 ,illinois1 area and in the still more ancient ,egyptian ruins at ,gerzah4 ,meteoritic iron has often been used in the manufacture of special swords1 daggers1 and knives for members of the royalty4 ,atilla and other early conquerors of ,europe boasted of 8swords from heaven40 ,emperor ,jehangir 7#afje-afbg7 ordered two sword blades1 a knife1 and a dagger to be smelted from the ,jalandhar1 ,india1 meteorite1 which fell on ,april #aj1 #afba4 ,in the early nineteenth century1 a sword was manufactured from a portion of the ,cape of ,good ,hope meteorite for presentation to ,alexander1 the ,emperor of ,russia4 ,even as late as the end of the nineteenth century1 several swords were made from a part of the ,shirihagi1 ,japan1 iron meteorite at the command of a member of the ,japanese court4 ,illustration3 ,a ,russian artist's pen-and-ink drawing of an extremely brilliant detonating fire ball or bolide4 ,see page #ajb4 ,in the ,europe of the ,middle ,ages1 meteorite falls and meteor showers1 as well as other 8unnatural0 events like comets1 eclipses1 and displays of the aurora borealis1 were regarded with superstitious awe by commoner and king alike4 ,the medieval mind always sought to interpret events connected in any way with the heavens as somehow influencing the affairs of men4 ,a bishop explained that the great meteor shower of ,april #d1 #ajie1 forecast 8the changes and wanderings of nations from kingdom to kingdom40 ,the fact1 however1 that the ,first ,crusade began within a year1 is mere coincidence4 ,in referring to celestial events1 ,shakespeare often expressed the view that was common in the ,middle ,ages and the ,renaissance4 ,an example is3 ,the bay-trees in our country are all wither'd ,and meteors fright the fixed stars of heaven2 ,the pale-faced moon looks bloody on the earth ,and lean-look'd prophets whisper fearful change1 4 4 4 4 4 4 ,these signs forerun the death or fall of kings4 7,richard ,,ii1 ,,ii1 iv1 #h-aa1 #ae7 ,yet the descent of meteorites from the heavens was not always regarded as a forewarning of bad fortune4 ,on ,november #af1 #adib1 a #bgi-pound meteorite fell at ,ensisheim in ,alsace1 not far from the battle line separating the armies of ,france and the ,holy ,roman ,empire4 ,emperor ,maximilian1 the leader of the ,empire's forces1 commanded that the fallen stone be carried to his castle4 ,there a formal war-council was held to determine what the strange event could mean4 ,illustration3 ,,courtesy ,,of ,,american ,,museum ,,of ,,natural ,,history ,drawing of ,andromedid meteor shower1 ,november #bg1 #ahgb4 ,the ,emperor and his councillors decided that the fall of the meteorite at such a time and place was an omen of divine favor which meant good fortune to the cause of the ,holy ,roman ,empire4 ,after breaking off two small pieces of the stone1 one for the ,duke of ,austria and one for himself1 the ,emperor forbade further damage to it4 ,he also gave orders that the stone be hung in the parish church in ,ensisheim for all to see4 ,in this way1 the ,ensisheim stone became the very first meteorite of witnessed fall to be preserved down to the present day--and all because of the superstition of a famous military leader4 ,the discussion to this point makes clear that in ancient1 medieval1 and ,renaissance times1 meteorite falls were considered as startling and disturbing events1 which frequently were interpreted in strange and mistaken ways4 ,but the fact that meteorites actually did fall from the heavens was not questioned4 ,as the so-called 8,age of ,reason0 opened1 a curious change in attitude toward meteorite falls took place4 ,at the very time that knowledge in general increased1 men of learning began to deny that meteorite falls occurred at all6 ,the scientists of the ,french ,academy1 in particular1 were very positive on this point4 ,since the era was one in which all ,europe sneezed if 8la belle ,france0 had a cold in the head1 it was a trying time not only for the early meteoriticists1 but for all who had the nerve to insist they had seen rocks fall from the sky4 ,by the end of the #agjj's1 the authorities had studied the evidence relating to meteorite falls and had completely rejected it4 ,they said that there was no 8proof0 whatever that 8stones fell from the heavens40 ,these early scientists openly sneered at people who claimed that they had seen meteorites fall4 ,it was felt that the spectators of such events either had merely been 8seeing things10 or had surely been reporting light and sound effects connected with nothing but ordinary thunderstorms4 ,when confronted with the 8fallen0 masses themselves1 the authorities often refused to examine them1 or if they did1 insisted that these masses were only rocks that had been struck by lightning4 ,such were the opinions of learned men around the close of the eighteenth century4 ,fortunately1 scientific facts have a stubborn way of winning out in the long run4 ,a major part of the credit for seeing that the truth regarding meteorite falls was at last recognized must go to ,e4 ,f4 ,f4 ,chladni1 a ,german physicist1 and to ,edward ,howard1 an ,english chemist4 ,in #agid1 ,chladni published an extremely important paper concerning a large spongelike mass of 8native iron0 found near ,krasnoyarsk1 ,russia4 ,this object had been discovered in #agdi by a ,russian blacksmith1 and it was studied in #aggb by ,p4 ,s4 ,pallas1 an early traveler4 ,chladni concluded that the mass of iron#aa must have fallen from the heavens1 because it had been 8fused0 7but not by man1 electricity1 or fire7 and also because there were no volcanoes anywhere around its place of find4 ,chladni supported his theory by listing numerous reports of meteorite falls dating from ancient and medieval times4 ,but ,chladni's fellow scientists flatly rejected his theory as clever but not satisfactory4 ,with the fall of the ,siena meteorites in ,italy on ,june #af1 #agid1 the controversy regarding the possibility that stones actually fell from the sky became particularly heated1 and remained so for nearly ten years4 ,during this interval1 two other important meteorite falls occurred3 ,wold ,cottage1 ,england1 on ,december #ac1 #agie1 and ,benares1 ,india1 on ,december #ai1 #agih4 ,scientists had a hard time finding explanations for these well-observed events1 and some of the theories put forward to account for them far outdid ,chladni's in 8cleverness10 if that be the correct word4 ,one scholar1 writing in #agif1 suggested that the masses which fell at ,siena resulted from the solidification at great height of volcanic ashes from ,mount ,vesuvius4 ,these ashes had supposedly been carried northward beyond ,siena and then been 8brought back by a northerly wind1 congealing from the air44440 ,fortunately1 in #ahjc ,edward ,howard's chemical work on meteorites came to a successful conclusion4 ,this patient chemist made analyses of samples from the ,siena1 ,wold ,cottage1 and ,benares falls and from an older ,bohemian fall4 ,he also had the samples studied mineralogically by a fellow scientist4 ,from the results of these investigations1 he drew the following conclusions1 which admirably supported ,chladni's well-reasoned and thoroughly documented theory regarding meteorite falls3 ,all four of the stones studied had very nearly the same composition4 ,despite the fact that the stones contained no new elements1 their mineralogical character differed in several important respects from that of any rocks found naturally on the earth4 ,the four masses must have had a common origin although their reported falls had been widely separated both in time and in space4 ,finally1 said ,howard1 it was quite possible that the stones had really fallen from the sky4 ,howard's views were soon put to the test4 ,shortly after the publication of his important paper1 a shower of stony meteorites fell near ,l',aigle1 ,france1 on ,april #bf1 #ahjc4 ,this event was carefully investigated by ,french scientists1 and they reluctantly admitted that about #c1jjj stones actually had fallen within an oval-shaped area about #f miles long by #b miles wide4 ,this shower of meteorites had been accompanied by the same light and sound effects mentioned in many of the old meteorite-fall reports collected by ,chladni1 effects now recognized as characteristic of the infall of meteorites upon the earth4 ,the evidence was overwhelming--stones really did fall from the sky4 ,in the camp of the enemy1 so to speak1 the reality of meteorite falls was established once and for all6 #ab4 ,,the ,,modern ,,view ,after the ,l',aigle shower of #ahjc1 a whole new era opened in the study of meteorites4 ,no longer did scientists hold these objects up to ridicule and scorn4 ,instead1 they came to regard meteorites as well worth collection and careful study4 ,the ,vienna ,museum1 the ,british ,museum1 the ,paris ,museum1 the ,academy of ,science of ,st4 ,petersburg 7now ,leningrad71 and the ,u4,s4 ,national ,museum began to build up splendid meteorite collections4 ,scientists in ,germany1 ,england1 ,france1 and ,russia engaged in the painstaking mineralogical study and classification of individual meteorite specimens4 ,the modern science of meteoritics is rooted deep in the nineteenth century4 ,many special fields of investigation had their beginnings then4 ,scientists became interested in the chemistry1 the mineralogy1 and the metallurgy of meteorites2 in the orbits of meteorites and the trajectories they follow through the earth's atmosphere down to impact with the ground2 and in the distribution of meteorite falls in space and time4 ,from this period we can date such milestones of progress in meteoritics as3 ,the discovery of the beautiful and significant ,widmansttten patterns characteristic of the majority of the irons1 and the less spectacular but equally important lines named for ,j4 ,g4 ,neumann1 the ,german meteoriticist who discovered them1 in #ahdh1 in the ,braunau meteorite4 ,the realization that there were many different kinds of meteorites and that these diverse objects were very important to an understanding of the internal structure and origin of the earth1 and perhaps of the ,solar ,system and the wider cosmos as well4 ,tentative explanations of the violent and terrifying light and sound effects connected with meteorite falls4 ,tentative explanations of such oval-shaped areas as shown above4 ,illustration3 ,typical distribution of meteorite fragments according to size1 within oval-shaped area of fall4 ,the larger masses of the shower carry farther on1 in the direction of the motion of the meteorite4 ,as early as #ahad1 investigators had noted this peculiarity of meteorite-shower distributions4 ,see pp4 #cb1 #hi1 #id4 ,by #ahej1 ,a4 ,boisse1 an early ,french geologist and meteoriticist1 had put forth the basic meteorite-planet hypothesis4 ,according to this theory of his1 meteorites are the fragments of a planet#ab that formerly orbited between ,mars and ,jupiter in what is now called the 8asteroid belt40 ,and untold millions of years ago1 this planet was shattered by some unknown but very great force1 possibly collision with another celestial body4 ,the structure of the meteorite-planet was considered to have been very much like that of the earth4 ,the various divisions of recognized meteorites were believed to be representatives of the several concentric1 or nested1 shells of material originally making up the destroyed planet4 ,these shells were progressively less dense with increasing distance from the center of the planet4 ,today ,boisse's theory is one of the most widely accepted as an explanation of at least one major category of the meteorites4 ,some modern investigators would insist that the meteorite-planet had a thin outer glassy shell from which the tektites came4 ,most of the larger fragments of the meteorite-planet1 now called the asteroids1 move so that the average asteroidal orbit very closely approximates the orbit of the original planet4 ,but many of the smaller fragments follow paths in space that differ considerably from the original meteorite-planet's orbit4 ,even some of the asteroids behave this way1 either because of the high speeds they acquired at the time of disruption of the meteorite-planet1 or because of the later influence of the major planets and particularly of the giant planet1 ,jupiter4 ,illustration3 ,a diagram 7not drawn to scale7 showing position of asteroid-belt with respect to the orbits of ,mars and ,jupiter4 ,the asteroids with average orbits move within this belt4 ,the non-typical asteroid indicated follows an orbit that brings it well inside that of the earth4 ,there are a number of asteroids with such peculiar orbits4 ,it is possible that in the past a nickel-iron asteroid in one of these orbits collided with the earth and produced the ,canyon ,diablo meteorite crater4 ,in fact1 at the present time1 several asteroids move well within the orbits of the earth and ,venus4 ,it is quite possible therefore that such a large meteorite crater as the one at ,canyon ,diablo1 was produced by the prehistoric fall of one of these small members of our ,solar ,system4 ,if so1 we have reason to believe that a core-fragment of the meteorite-planet came to earth at ,canyon ,diablo4 ,for the extensive mining operations carried out there during the last half-century have shown that the projectile responsible for this greatest of all meteoritic shell-holes in the face of ,mother ,earth was a mass of solid nickel-iron1 which in all likelihood was core material4 ,the lengthy and costly series of mining operations at ,canyon ,diablo were all undertaken in the hope of locating the 8main mass0 of this huge projectile and thus of opening up what might be called a cosmic-lode of quite valuable metals4 ,unfortunately1 the miners overlooked the fact that impacts at meteoritic speeds produced almost incredible amounts of heat4 ,even the solid iron meteorites are vaporized and widely dispersed at the temperatures resulting from such impacts1 as we have seen was the case at ,wabar 7see ,chapter #d74 ,so it was at ,canyon ,diablo4 ,the idea of a cosmic-metal mine might at first strike some readers as too futuristic to take seriously4 ,but the necessity for catching a core-fragment before it enters the consuming atmosphere of our planet is really nothing new4 ,as far back as #aici1 the senior author had occasion to point out that if we wish to start a successful cosmic-metal mine1 we must catch our core-fragment before it is turned into unminable vapor4 ,this point will come up again in the next chapter4 ,illustration3 ,cross-section of ,boisse's hypothetical meteorite-planet4 ,fragmentation of this sphere was believed to have given rise to the following divisions of meteorites3 ,the iron meteorites came from ,a1 the dense nickel-iron core4 ,the stony-iron meteorites came from ,b1 the intermediate zone of cellular nickel-iron and silicate minerals4 ,the stony meteorites came from ,c1 the outer zone of silicate minerals in which relatively little or no nickel-iron is present4 ,the chondrites were believed to come from the inner portion of this zone2 the achondrites1 from the outer portion4 ,there are several other theories of the origin of meteorites interesting enough to mention4 ,the early view that the meteorites were debris thrown out by ancient volcanoes on the moon or recent ones on the earth came to be discredited largely on physical grounds4 ,on the other hand1 extremely violent primordial volcanoes on the earth 7not the weak ones of historic times1 like ,aetna or ,vesuvius7 could have ejected material that in much later times fell1 and continues to fall back on our globe4 ,this theory has not been ruled out and it still receives support1 for example1 from some authorities in the ,u4,s4,s4,r4 ,these same ,russian scientists take most seriously a suggestion that the meteorites 7and comets as well7 were thrown out by volcanoes believed to exist on the planet1 ,jupiter--a theory dating back almost a century to the ,english astronomer1 ,r4 ,a4 ,proctor4 ,some scientists believe that meteorites represent the congealed remains of gaseous bolts of matter ejected by the sun4 ,others interpret them as fragments of comets that have been torn apart by passing too close to the sun1 which is the most powerful gravitational center in the ,solar ,system4 ,chemists1 geologists1 astronomers1 and physicists--as well as the meteoriticists themselves--are constantly working toward a solution of the problem of the meteorites4 ,where do these bodies come from8 ,what can we learn from them about their age and origin and about the age and origin of our ,solar ,system8 ,years may be required1 but eventually the riddle of the meteorites will be solved by the patient1 concerted efforts of men and women of science4 ,illustration3 ,collapsed mine buildings in the bottom of the ,canyon ,diablo meteorite crater4 ,a shaft was put down here in one of several unsuccessful attempts to locate the main mass of the meteorite4 ,see pp4 #dd-eb4 #ac4 ,,present ,,and ,,future ,,applications ,so far we have considered what might be called the 8pure0 rather than the 8applied0 side of the study of meteorites4 ,the investigator in any pure science asks of a new discovery1 8,what does this tell me about the universe8 ,how does it better help me to understand the laws of nature80 ,of the same discovery1 however1 the worker in an applied science will ask1 8,what practical use can be made of this gain in knowledge8 ,what can it be made to do for mankind in general80 ,these questions reveal a decided difference in viewpoint1 but this difference does not reflect unfavorably on either class of scientists4 ,in fact1 there is a great deal of truth in the saying 8,today's pure science is tomorrow's applied40 ,actually1 ways and means of taking advantage of seemingly useless scientific discoveries are constantly being found4 ,the most famous example of this principle is the development of the atomic bomb from the results of ,einstein's researches in the abstract field of relativity4 ,here the seemingly mystic formula ,e mc came to have far-reaching practical applications indeed6 ,meteoritics has some exceedingly practical applications4 ,far from being completely 8out of this world0--as the recovered meteorites themselves originally were--this science has been and can be made to serve mankind in a number of rather unexpected ways4 ,meteoritics1 the onetime 8stepchild of astronomy10 is currently being regarded with ever-increasing respect by scientists and engineers working in many different fields4 ,consider1 first of all1 the stainless steels that are so widely used in modern industry1 and even the fine satin-sheen stainless 8silverware0 that graces our dining tables4 ,these have wisely been patterned after a natural alloy with lasting qualities of strength1 tenacity1 and resistance to corrosion4 ,this natural alloy is the one making up the iron meteorites4 ,its toughness and durability became well known wherever attempts were made to section these metallic meteorites4 ,specially designed and extra-powerful sawing equipment is required to slice meteoritic iron1 and even with it1 progress is painfully slow4 ,so astounded were those who first tried to cut iron meteorites with ordinary metal saws that one of the earliest practical results was the development of battleship armor plate composed of a commercial alloy called 8meteor steel10 which mimicked the composition of the iron meteorites4 ,of course1 a good deal of the difficulty of sectioning meteorites arises from the fact that those doing the cutting are trying hard not to waste valuable meteoritic material4 ,every precaution is taken to keep the amount of 8sawdust0 to a minimum1 for such finely ground up and contaminated meteoritic material is of little scientific use4 ,and1 in addition1 scientists must guard against heating meteorites to high temperatures because such heating destroys the delicate internal structure of the masses4 ,if these two considerations 7loss of material and overheating7 were unimportant1 even a large meteorite could easily be divided up by use of such high-powered oxyacetylene torches as are used to dissect huge obsolete battleships4 ,at the ,institute of ,meteoritics1 a thin1 water-cooled blade of soft iron is driven slowly back and forth by an electric motor4 ,carborundum grit in water suspension is fed evenly into the narrow cut over its entire length4 ,this grit becomes imbedded in the lower edge of the soft iron blade1 which then acts as a 8many-toothed0 metal saw4 ,several meteorites can be sectioned simultaneously by this multiblade saw4 ,in the future1 such newly developed methods as high-speed particle jet streams or ultrasonic devices may be used to section meteorites both rapidly and economically4 ,in the field of cosmic ray studies1 particularly those concerned with the protection of space travelers from harmful radiation1 meteoritics can be of help4 ,the recovered meteorites have already come through those regions that would be crossed by even the farthest-ranging spaceships4 ,consequently1 a great deal can be learned from the study of meteorites about the intensity of the cosmic radiation that the crews of such ships must face once they get outside the earth's protective air-shield4 ,the first study of this type was made in ,may1 #aidh1 at the ,institute for ,nuclear ,studies of the ,university of ,chicago 7now the ,enrico ,fermi ,institute74 ,scientists made radioactivity tests on samples of the ,norton ,county meteorite donated for this purpose by the ,institute of ,meteoritics and air-expressed to ,chicago because of the intense interest in the radioactivity question4 ,in ,october1 #aidi1 ,english investigators ran similar tests at the ,londonderry ,laboratory for ,radiochemistry1 ,durham1 ,england1 on samples of the freshly fallen ,beddgelert1 ,north ,wales1 meteorite discussed on pp4 #fi-gj4 ,the results of these two pioneer studies were negative because the 8,model-,t0 instruments available in #aidh and #aidi were not sensitive enough to detect the relatively low radioactivities present4 ,illustration3 ,the #f-;blade meteorite gang-saw in the machine shop at the ,institute of ,meteoritics4 ,in #aiee1 however1 scientists at ,purdue ,university1 using more refined counters1 studied small nuggets of nickel-iron1 also from the ,norton meteorite4 ,this time1 the results of the radioactivity tests were positive4 ,the investigators detected tritium 7an isotope of hydrogen produced by cosmic-ray bombardment7 in the samples4 ,furthermore1 the amount of this rare isotope present indicated that the intensity of cosmic radiation outside the earth's atmosphere may be very much higher than had previously been thought possible4 8,forewarned is forearmed10 and from the standpoint of future astronauts1 this is as practical a result as one could wish for6 ,in the relatively near future1 men will certainly land on the surface of the moon4 ,we know from radiometric studies that some degree of radioactivity is induced in meteorites by the full-intensity cosmic radiation to which they have been exposed during their motion through space4 ,the nearly airless moon1 like the meteorites1 has also been exposed to very intense cosmic radiation for a long time4 ,so those who are planning to land on our satellite are concerned about the radioactivities they will encounter when they begin their explorations of the lunar surface4 ,suppose that extra-sensitive instruments were designed to pick up and measure the radioactivities4 ,suppose further that these instruments were mounted in a space-probe put in an orbit circling closely about the moon4 ,plans for such a project are now under way4 ,what types and intensities of lunar radioactivities might such probe-mounted instruments record8 ,until such a space-probe becomes available1 earth-bound space-scientists are seeking at least a preliminary answer to this question4 ,they are doing this by investigating the natural 8probes0 that have come to us from space--the meteorites4 ,investigators have undertaken such studies very recently by employing a new radiometric method technically called gamma-ray spectroscopy4 ,work of this sort has been and is being done at the ,los ,alamos1 ,new ,mexico1 ,scientific ,laboratory on scores of meteorite and tektite specimens loaned to the ,laboratory by the ,institute of ,meteoritics4 ,some of the individual meteorite specimens tested weighed as much as #cg pounds1 and are probably the largest single extra-terrestrial masses yet tested for cosmic ray-induced radioactivities4 ,let us turn now to another important application of meteoritics4 ,any body in motion through the air or in space has a 8striking power0 of sorts4 ,for some objects1 this striking power1 which is technically known as ballistic potential1 is very weak1 as in the case of silky milkweed-down drifting through the air4 ,hailstones have a good deal more striking power1 as may have been painfully demonstrated on your own head4 ,and1 finally1 such masses as falling meteorites 7and especially those orbiting in space1 unretarded by atmospheric resistance7 have an extraordinarily formidable ballistic potential4 ,this is because meteorites are not only tough and dense1 as good projectiles must be1 but are also moving at high velocities--particularly high if the meteorites come into the ,solar ,system from interstellar space4 ,for this reason1 the speeds of meteorites are very important to scientists responsible for rocket flights and for keeping satellites aloft over long periods of time4 ,clearly1 these men must have as accurate information as possible on where and how fast meteoritic particles are moving1 so as to chart the safest routes for spaceships1 and to develop satisfactory means of protecting rockets and satellites against the effects of bombardment by the smaller meteorites4 ,for these 8small-fry0 cosmic missiles are so numerous that many of them are sure to be encountered even in brief flights outside the earth's atmosphere4 ,such information might also prove valuable in the future to the crews of spaceships on long flights into deep space4 ,such men may face the life or death problem of taking successful 8evasive action0 against giant meteorites that will seem like flying hills and mountains4 ,a strong parallelism exists between a meteorite fall and the re-entry of a nose-cone or data-capsule into the atmosphere4 ,to a considerable extent1 the difficult problems connected with the latter are being attacked at present through careful studies of meteorites4 ,from the air-sculptured shapes of meteorites1 their crustal flow patterns1 and the thicknesses and types of fusion crusts they show1 scientists are learning a great deal about certain factors connected with the re-entry problem4 ,these factors include rate of vaporization1 effects of extreme temperatures1 and types of sculpturing to be expected as a result of encountering the resisting molecules of the atmosphere4 ,illustration3 ,relationship between 7,a7 the trajectory of a falling meteorite1 and 7,b7 the re-entry stage of a ,v-#b rocket4 ,the solid lines indicate the similar portions of the two trajectories4 ,a4 ,a ,,meteorite ,,fall ,b4 ,a ,v-#b ,,re-,,entry ,one of the most obvious applications of meteoritics in the future will grow out of the well-known fact that our earthly resources of many strategic materials--especially metals like iron and nickel--are fast becoming exhausted4 ,the population of the earth is increasing at a mad pace1 and an end to metal-consuming wars is still not in sight4 ,the need for such metals can only become more and more acute4 ,according to one of the currently favored explanations of the origin of the meteorites1 the core-fragments of the parent meteorite-planet are solid masses of nickel-iron alloy--like the mass that blasted out the ,canyon ,diablo meteorite crater4 ,if this meteorite-planet hypothesis finally wins general acceptance1 the meteoriticist of the future is almost sure to be set the task of pin-pointing as exactly as possible the whereabouts in space and time of the most easily accessible cosmic nickel-iron lodes of this sort4 ,once he has given an answer1 the space engineers will take over1 and mining operations will be started on the unlimited sources of essential metals to be found in outer space4 ,initially1 no doubt1 metal recoveries will be freighted back to earth in rocket-load lots4 ,but as the need for iron and nickel increases on a metal-hungry earth1 vast engineering projects may well be undertaken to 8snare0 the larger metal meteorites and equip them with rocket motors4 ,this will be done so that by use of rocket power1 the natural orbits of the meteorites can be changed into orbits bringing them back to earth4 ,unlike the natural1 uncontrolled ,canyon ,diablo meteorite fall that vaporized what would have been a rich nickel-iron deposit1 the rocket-controlled meteoritic 8metal mines0 will be eased down to earth all in one piece4 ,reading of the possibility of sending out expeditions to find large iron meteorites in the depths of space may bring to your mind an image of the fearless mariners of old who sailed their stout ships over dangerous1 often uncharted seas in search of the great whales4 ,the rocket crews of day-after-tomorrow will no doubt be equally fearless and resourceful as they navigate the sea of space1 intent on capturing the great 8metal mines0 of the future4 ,the experience gained in such space-mining ventures will then be carried over into expeditions to ensnare the larger stony-iron meteorites4 ,these masses of iron and stone will offer less favorable mining possibilities1 but they can be turned into rocket-propelled and guided de luxe space-cruisers4 ,by this term1 we do not mean that these natural space-ships will house all the luxuries of the ocean-liners advertised in the travel magazines4 ,rather1 we see them as providing roomy1 comfortable 8underground0 living quarters4 ,furthermore1 their occupants will be adequately protected by great thicknesses of metal and rock from the injurious radiations of empty space1 and the meteorites that make the term 8empty space0 something of a misnomer4 ,initially1 such worlds-in-miniature will be much sought after as laboratory sites where the more violent and dangerous of the many experimental tests which venturesome man will wish to conduct can be carried on without danger to the close-packed billions populating the then-crowded earth4 ,later on1 these meteorites-turned-into-space-ships may be used to explore the dangerous and faraway corners of the ,solar ,system1 since the very substance of each massive meteoritic rocket-body will serve as an adequate and handy source of fuel supply4 ,when men have learned to live on such 8homes away from home10 it is quite possible that the larger of these modified meteorites1 after their interiors have been opened up for occupancy by the inroads of the fuel-hungry rocket-motors1 may be steered into neighborly orbits about old ,mother ,earth4 ,here1 these 8natural0 satellites will assume the unexciting but necessary roles of the extra living quarters that by then will be so urgently needed to accommodate the mushrooming population of the world of the future4 ,people who live in these super-urban outliers of ,mother ,earth may take the same pride in their natural1 if converted1 homes as many former city dwellers now take in the old-fashioned sprawling farmhouses they have rebuilt and occupied4 ,perhaps one of your descendants will live in such a meteorite-orb1 and occasionally point the finger of scorn at the more elegant but unpleasantly overcrowded artificial satellites preferred by those migrants from teeming earth who lack the true pioneering instinct4 ,who knows6 ,,for ,,further ,,reading ,if you are especially interested in meteoritics1 you already may have read some good books on general astronomy4 ,there are many and most of them are not too advanced for the beginner4 ,unfortunately1 these books devote but little space to meteoritics1 the 8,johnny-come-lately0 of astronomy4 ,almost all of the writings on meteors and meteorites you will find largely profitable to read are in professional meteoritical publications4 ,a selected list of such publications1 containing much or at least a worthwhile amount of material you will now be able to understand1 is given below4 ,your chief difficulty in using this list will be in finding some of the more important items in the holdings of your public library1 unless it is a large and well-stocked one4 ,your librarian1 however1 may be able to help you get the item from some other library--perhaps from that of a nearby university or college4 ,,meteoric ,,astronomy ,,mebane1 ,a4 ,d4 8,the ,canadian ,fireball ,procession of #aiac1 ,february #i10 ,meteoritics1 ,vol4 #a1 ,no4 #d 7#aief71 pp4 #dje-dba4 ,eyewitness accounts of the most famous fireball procession on record4 ,,olivier1 ,c4 ,p4 ,meteors1 ,williams and ,wilkins1 ,baltimore1 #aibe4 ,an exhaustive survey of work done by visual meteor-observers4 ,,schiaparelli1 ,g4 ,v4 ,shooting ,stars1 a translation by ,c4 ,c4 ,wylie and ,j4 ,r4 ,naiden1 published in the ,proceedings1 ,iowa ,academy of ,science1 ,vol4 #ej 7#aidc71 pp4 #dh-aec4 ,a pioneer treatise1 dated #ahfg1 which is basic to later work in this field4 ,,whipple1 ,f4 ,l4 8,photographic ,meteor ,studies1 ,i10 ,proceedings1 ,american ,philosophical ,society1 ,vol4 #gi1 ,no4 #d 7#aich71 pp4 #dii-edh4 ,fundamental paper on the subject4 ,of the six meteors analyzed1 five followed elliptical orbits and one1 a strongly hyperbolic orbit4 ,,meteorites ,,farrington1 ,o4 ,c4 8,a ,catalogue of the ,meteorites of ,north ,america to ,january #a1 #aiji10 ,memoirs1 ,national ,academy of ,sciences1 ,vol4 #ac 7#aiae74 ,contains fascinating accounts of the phenomena connected with meteorite falls1 interspersed with lengthy technical chemical and microscopic studies of meteorites4 ,,farrington1 ,o4 ,c4 ,meteorites published by the author1 ,chicago1 #aiae4 ,the classic ,american work on meteorites4 ,the first half of the book is popular2 the last half is technical4 ,,hey1 ,m4 ,h4 and ,,prior1 ,g4 ,t4 ,catalogue of ,meteorites1 ,william ,clowes ,sons1 ,london1 #aiec4 ,an exhaustive catalog of all recognized and also1 unfortunately1 of many doubtful meteorite falls and finds1 from the beginning of the historical record up to ,december #aieb4 ,,lapaz1 ,,lincoln4 8,the ,achondritic ,shower of ,february #ah1 #aidh10 ,publications1 ,astronomical ,society of the ,pacific1 ,vol4 #fa 7#aidi71 pp4 #fc-gc4 ,,lapaz1 ,,lincoln4 8,the ,effects of ,meteorites upon the ,earth10 ,advances in ,geophysics1 ,vol4 #d1 edited by ,h4 ,e4 ,landsberg1 ,academic ,press1 ,new ,york1 #aieh1 pp4 #bag-cej4 ,a monograph covering such topics as meteorite hits upon buildings and people1 meteorite detectors1 and the nature and age of meteorite craters4 ,,leonard1 ,f4 ,c4 8,the ,furnas ,county1 ,kansas1 ,achondritic ,fall 7#ajjj1djj710 ,contributions1 ,meteoritical ,society1 ,vol4 #d 7#aidh71 pp4 #ach-ada4 ,this paper and the eighth item1 above1 discuss the phenomena of the fall of the largest aerolite so far recovered anywhere in the world4 ,,merrill1 ,g4 ,p4 8,the ,story of ,meteorites10 ,minerals from ,earth and ,sky1 ,vol4 #c1 ,part ,i1 ,smithsonian ,scientific ,series1 #aibi1 pp4 #a-afc4 ,a chiefly popular survey of the subject by a master meteoriticist4 ,,perry1 ,s4 ,h4 ,the ,metallography of ,meteoric meteoritic ,iron1 ,u4 ,s4 ,national ,museum ,bulletin ,no4 #ahd 7#aidd74 ,a summary of knowledge on the subject1 supplemented by exceptionally fine photographs of etched meteorite sections4 ,,swindel1 ,g4 ,w41 ,,jr41 and ,,jones1 ,,walter ,b4 8,the ,sylacauga1 ,talladega ,county1 ,alabama1 ,aerolite3 ,a ,recent ,meteoritic ,fall that ,injured a ,human ,being10 ,meteoritics1 ,vol4 #a1 ,no4 #b 7#aied71 pp4 #abe-acb4 ,,white1 ,c4 ,s4 and ,,benson1 ,,otis ,o4 7editors7 ,physics and ,medicine of the ,upper ,atmosphere1 ,university of ,new ,mexico ,press1 ,albuquerque1 #aieb4 ,see ,chapter ,x1 8,meteoritic ,phenomena and ,meteorites10 by ,f4 ,l4 ,whipple1 pp4 #acg-agj2 and ,chapter ,,xix1 8,meteoroids1 ,meteorites1 and ,hyperbolic ,meteoritic ,velocities10 by ,lincoln ,la,paz1 pp4 #ceb-cic4 ,modern views on the meteorite velocity controversy4 ,,meteorite ,,craters ,,lapaz1 ,,lincoln4 8,the ,craters on the ,moon10 ,scientific ,american1 ,vol4 #aha1 ,no4 #d 7#aidi71 pp4 #b-c4 ,a popular exposition of the ,bnard-,wasiutynski theory of the origin of the ordinary 7nonrayed7 craters on the moon4 ,,spencer1 ,l4 ,j4 8,meteorite ,craters as ,topographical ,features on the ,earth's ,surface10 ,geographical ,journal1 ,vol4 #ha 7#aicc71 pp4 #bbg-bdh4 ,the classic paper on terrestrial meteorite craters4 ,,meteoritic ,,dust ,,buddhue1 ,j4 ,d4 ,meteoritic ,dust1 ,the ,university of ,new ,mexico ,press1 ,albuquerque1 #aiej4 ,an account of the various techniques used in collecting and studying meteoritic dust2 and also of the conclusions drawn from the study of such dust4 ,,index ,a achondrites1 #abf1 #afc1 #agh ,adelie ,land stone1 #gh ,adrar iron1 #ch1 #dj aerolites1 #agh1 #agi see also1 stones1 meteoritic age of meteorites and_/or craters1 #ej1 #eb ,aggie ,creek iron1 #gf ,ahnighito iron1 #cf1 #abh ,algoma meteorite1 #ge 8,alley ,oop's shillelagh10 #abf altitude1 #hh1 #ij1 #aje1 #ajf ,american ,meteor ,society1 #aaf ,american ,museum of ,natural ,history1 #cg ,anderson ,township meteorites1 #gf ,andhra stone1 #adg-h ,andromeda1 ,great ,spiral ,nebula in1 #b ,andromedid shower1 #aec anthills1 meteorites in1 #abh anti-matter1 #eh-fj ,aouelloul crater1 #fe appearance and disappearance of meteors1 #hf1 #id1 #ajf applied science1 #aff archeologists1 #gf1 #aej areas of fall1 #ac-d1 #bd1 #bf1 #cb1 #hi1 #id1 #aei armor plate1 #afg asteroid belt and orbits1 #afj-a astronautics1 #aaj1 #afh1 #agj-f ataxites1 #abj ,athens1 multiple fireball over1 #adi australites1 #acd1 #adj azimuth1 astronomical1 #hh ,b ,bacubirito iron1 #abh ,bald ,eagle iron1 #gf ballistic potential1 #aga ,baxter stone1 #gc ,bear ,lodge iron1 #gf ,beddgelert stone1 #fi-gj1 #gc1 #afh bediasites1 #acf1 #acg ,belly ,river stone1 #aca ,benares meteorite1 #aef ,bendego iron1 #abh ,benld stone1 #gc ,benson1 ,o4 ,o41 #agi ,bethlehem stone1 #gc betyls1 #adh1 #aej ,bible1 meteorite mentioned in1 #adg ,bielid shower1 #aaf 8blackfellows' buttons10 #acd ,black ,stone of the ,kaaba1 #adg ,boisse1 ,a41 #afj1 #afc bolides1 #ajb1 #aea ,braunau iron1 #gc ,brenham craters and meteorites1 #eb1 #fe1 #ff1 #gh ,box ,hole ,station crater1 #fe ,bridgewater meteorite1 #ge ,british ,museum1 #acf1 #aeh ,buddhue1 ,j4 ,d41 #agi ,c ,campo del ,cielo craters1 #ej1 #fe ,canyon ,diablo crater1 #dd-eb1 #fe1 #ff1 #ge1 #if1 #afa1 #afb1 #afe1 #agd ,cape of ,good ,hope iron1 #aej ,cape ,york iron1 #cf1 #cg ,carlton meteorite1 #ge ,casas ,grandes iron1 #gf charms1 meteorites used as1 #acd1 #acf see also sacred meteorites2 superstitions ,chesterfield meteorite1 #ge ,chladni1 ,e4 ,f4 ,f41 #aee-g chondrules and chondrites1 #abd-f1 #afc ,chubb crater1 #eb-d coins depicting meteorites1 #adh1 #aej collection of meteorites in institutions1 #bj1 #cb1 #cd1 #cg1 #ch1 #dj-a1 #ij1 #acf1 #aeh comets1 #aad1 #adj1 #afd composition of meteor-forming particles1 #afj-g composition of meteorites1 #aah-bf1 #afc1 #agi composition of tektites1 #acf-h ,constantia stone1 #gd contraterrene matter1 #ef1 #eh-fj convection-current hypothesis1 #fc-d cosmic metal mine1 #afb1 #agd-f cosmic rays1 #afh-ga craters1 #ag1 #ah1 #bj1 #db-fe1 #ff1 #if1 #adc1 #agh1 #agi ,d ,dalgaranga crater1 #fe daubreelite1 #abd destruction by meteorites1 #aa1 #ae1 #af-ai1 #ed-g1 #fh-gj1 #gc-d1 #agh diamond-bearing meteorite1 #hb direction measures1 #bc1 #bd1 #hf-i1 #aaj distribution of meteorites1 #ff-fh1 #gb1 #adj-c1 #aei dog and meteorite1 #gc doubters of meteorites1 #aed-g 8dumbbells10 #ace1 #acf 8dust balls10 #ajf dust1 meteoritic1 #ajb1 #aaf-g1 #agi ,e 8earth-rings10 #adb earth-trace1 #ib eating a meteorite1 #hb ,einstein1 ,a41 #aff elements in meteorites1 #aah-bd elements in meteor-forming particles1 #ajg elevation1 apparent1 #hh1 #ij see also altitude 8end-point10 #af1 #hf-ia ,enrico ,fermi ,institute1 #afh ,ensisheim stone1 #aeb1 #aed ,eta-,aquarid shower1 #aad etching meteorites1 #aai-abc evaporation1 see vaporization 8explosions0 of meteors and_/or meteorites1 #ah1 #bc1 #be1 #ee1 #ef-fj1 #fc1 #hf1 #ib ,f fall1 determining area of1 #ac-ad1 #bd1 #bf see also oval-shaped areas of fall falls1 witnessed1 #aa-bb1 #bc-cd1 #fg1 #fh-gb1 #hb1 #hd-ie ,farrington1 ,o4 ,c41 #agh farmers as meteorite finders1 #bh1 #cj1 #ge-f ,fermi 7,enrico7 ,institute1 #afh fireballs1 #b1 #aj1 #aa-ac1 #bc-e1 #ed1 #fi1 #hd-ib1 #ajb1 #ajf1 #adi1 #aea fishermen net meteorite1 #gh fixes1 #hd-ij 8flanged buttons10 #ace1 #acf flight-path1 see trajectory ,flows meteorite1 #hb footwarmer1 meteorite used as1 #gh 8fossil0 meteorites1 #add-f funnels1 impact and penetration1 #bj1 #bi1 #cb1 #cc1 #db1 #dd ,furnas ,county stone1 #bi1 #ca1 #cb-d1 #abh1 #agh see also ,norton ,county fall fusion crust1 #bj1 #ba1 #acj1 #acb1 #adj1 #adh1 #agb ,g ,galle1 ,j4 ,g41 #ib gamma-ray spectroscopy1 #aga ,geminid shower1 #aad ,giacobinid shower1 #ajc1 #aad1 #aae ,giacobini-,zinner comet1 #aad glass1 #ach1 #ade see also silica-glass2 tektites ,glorieta iron1 #abf great-circle distributions1 #adj-c ,h ,harvard meteor-photographs1 #aaj-a ,haviland craters1 #ej1 #eb1 #fe1 #ff ,hayden ,planetarium1 #abi height1 #hh1 #ij1 #aje1 #ajf ,henbury craters1 #ej1 #fe ,hey1 ,m4 ,h41 #agh hexahedrites1 #aai1 #abj ,holbrook stone shower1 #abh ,howard1 ,e41 #aee-g hunting meteorites1 methods of1 #hd-ajj ,i 8ices10 #ajf ,illinois ,gulch iron1 #gf impactites1 #adc-e ,india1 ,museum of the ,geological ,survey of1 #da ,indians1 #da1 #gf1 #aej ,institute for ,nuclear ,studies1 #afh ,institute of ,meteoritics1 #e1 #bd1 #bf-cb1 #hj1 #hd1 #if1 #afh1 #afi1 #aga intersecting lines of sight1 #hd-ij interstellar space1 #ib1 #aga irons1 #ai1 #cf1 #cg1 #ci1 #dj1 #da1 #dh1 #gc1 #ge1 #gf1 #gh1 #hb1 #ii1 #aaf1 #aah1 #abj1 #aba1 #abh1 #abi1 #acc1 #adc1 #aej1 #aee1 #afc1 #afg1 #agd-e1 #agi ,j ,jones1 ,w4 ,b41 #agi ,jupiter1 #ajb1 #adb1 #afj1 #afa1 #afd ,k ,kaalijarv crater1 #fe kamacite1 #abd ,kasamatsu stone1 #gd ,kayser1 ,e41 #ib ,kenton iron1 #ge ,kilbourn stone1 #gd ,klepesta1 ,j41 #b ,krasnoyarsk iron1 #aee ,l laboratory procedures1 #e1 #ha1 #hc1 #aah1 #abj1 #abh1 #afg-ga ,la ,caille meteorite1 #gh ,l',aigle stone shower1 #aeg1 #aeh ,lake ,murray iron1 #gg1 #gi1 #hj-c ,lake ,okeechobee stone1 #gh ,la,paz1 ,l41 #agh1 #agi largest meteorites1 see weights and weighing of meteorites ,leningrad 7,st4 ,petersburg71 ,academy of ,science of1 #aeh ,leonard1 ,f4 ,c41 #agh ,leonid shower1 #aad1 #aae ,lick ,creek iron1 #gf ,londonderry ,laboratory for ,radiochemistry1 #afh ,los ,alamos ,scientific ,laboratory1 #aga 8lost0 meteorites1 #ch1 #dj1 #da1 #hj1 #hb1 #ie lunar craters1 #fj-d1 #agi see also moon1 craters on ,lyrid shower1 #aab1 #aad ,m magic attributed to meteorites1 see superstitions ,mars1 #afj1 #afa 8,martian spaceship10 #fj ,maximilian ,i1 #aeb-d ,mazapil iron1 #aaf ,mebane1 ,a4 ,d41 #agg ,medvedev1 ,p4 ,i41 #aj ,merrill1 ,g4 ,p41 #agh ,mesaverde iron1 #gf metals1 meteorites as sources of1 #agd-e meteorite detectors1 #dh1 #eb1 #if-ajj1 #agh meteoriteless meteorite crater1 #ef meteorite-planet hypothesis1 #adj1 #afj1 #afc1 #agd meteorite showers1 #gc-d1 #abh1 #aeg1 #aeh1 #aei meteorites1 true or false1 #acj-c meteoritics1 #e1 #ajd1 #aff-g meteors1 #aja-ag meteor showers1 #ajc1 #aaa1 #aab-aaf1 #aag1 #aeb1 #aec meteor steel1 #afg micro-meteorites1 see dust1 meteoritic minerals in meteorites1 #abj-f1 #aef1 #afc miners as meteorite finders1 #gj1 #gf1 #add mining in space1 #afb1 #agd-f ,montezuma temple iron1 #gf moon1 #fj-d1 #adj1 #agj moon1 craters on1 #fj-d1 #agi ,morito iron1 #abh ,moscow1 ,academy of ,sciences at1 #bj ,mount ,darwin1 ,tasmania1 crater1 #fe2 silica-glass1 #adc ,mount ,joy iron1 #ge-f ,murfreesboro iron1 #gf ,n 8natural nuclear explosion10 #fj ,neumann1 ,j41 #aeh nickel-iron1 #ai1 #cb1 #if1 #ih1 #aah1 #abj1 #abb1 #abc1 #abd1 #abf1 #acb1 #adc1 #aej1 #afa1 #afc1 #agj1 #agd ,norton ,county fall1 #bc-cd1 #ij1 #ic1 #id1 #if1 #abf1 #abh1 #acj1 #afh ,novo-,urei stone1 #hb ,o obsidian mistaken for tektite1 #ach-i octahedrites1 #abj1 #aba ,odessa crater1 #dc1 #dd1 #eb1 #fe1 #ff1 #ge oldest collection of meteorites1 #gf oldest crater1 #eb ,olivier1 ,c4 ,p41 #aaf1 #agg ,opava irons1 #gf orbits1 #ajh-aab1 #afj1 #afa origin of meteorites1 #afj1 #afc1 #afd1 #agd ,orionid shower1 #aab1 #aad oval-shaped areas of fall1 #cb1 #hi1 #id1 #aei ownership of meteorites1 #cf1 #ch ,p ,pallas1 ,p4 ,s41 #aee pallasites1 #abb1 #aee ,pantar stone shower1 #gd parallax and parallactic displacement1 #aje1 #ajf ,paris1 ,museum of ,natural ,history at1 #ch1 #aeh paths of meteors1 #hd-id1 #aaf see also earth-trace2 orbits2 speeds2 trajectory2 velocity patterns1 structural1 #abj1 #aba1 #agb ,pawnee ,indians1 #da ,peary1 ,r4 ,e41 #cf1 #cg1 #abh ,perry1 ,s4 ,h41 #agi ,perseid shower1 #aad1 #aae person struck by meteorite1 #gj-b1 #agh1 #agi piezoglyphs1 #aca1 #acb ,pittsburgh iron1 #gh1 #hj plessite1 #abd plotting meteor paths1 #aaf ,plymouth meteorite1 #ge ,podkamennaya ,tunguska fall1 #ej1 #ed-fj1 #fe1 #ajb polishing meteorites1 #e1 #aah1 #abj1 #abc ,port ,orford stony-iron1 #dj ,prague ,observatory1 #b ,prior1 ,g4 ,t41 #agh ,proctor1 ,r4 ,a41 #afd ,pultusk fireball1 #ib ,purdue ,university1 #agj pure science1 #aff 8purloined0 meteorite1 #cf1 #ci ,q ,quadrantid shower1 #aad ,r radiant of meteor shower1 #aab1 #aac radioactivities1 #e1 #fj1 #acc1 #ach1 #afh1 #agj-a ,rafrti iron1 #gh rainfall1 connected with meteor showers1 #aag random distribution1 #fb ray-craters1 #fj-d recoveries of meteorites1 #ad-bb1 #bd1 #bf-h1 #ca1 #cc1 #ce1 #ge-hb1 #hd-ajj ,red ,river iron1 #da re-entry1 #agb1 #agc reports1 eyewitness1 #bc1 #bd1 #hd1 #hf1 #ij1 #ib1 #id-e reversed matter1 #ef1 #eh-fj ,richland iron1 #ge ,rigel1 #ib rocketry1 #aaj1 #agd-f ,rojansky1 ,v41 #eh ,s sacred meteorites1 #adg-ej see also superstitions ,san ,emigdio stone1 #hj satellites1 man-made1 #agb ,saturn's rings1 #adb sawing meteorites1 #ha1 #afg-i ,schiaparelli1 ,g4 ,v41 #agg ,schmidt1 ,j4 ,f4 ,j41 #adi schreibersite1 #abd ,scottsville iron1 #gf ,seelsgen iron1 #ge ,shakespeare1 meteors mentioned by1 #aeb shale balls1 #dh1 #acc shapes of meteorites1 #ah1 #cb1 #abf-h1 #acd-g1 #adj1 #agb ,shirihagi iron1 #aej 8shooting stars10 #ajd showers1 meteor1 #ajc1 #aaa1 #aab-aaf1 #aag1 #aeb1 #aec showers1 meteorite1 #gc1 #gd1 #abh1 #aeg1 #aeh1 #aei ,siena fall1 #aef ,sikhote-,alin fall1 see ,ussuri silica-glass1 #ej1 #ed1 #adc see also glass2 tektites silicate-siderites1 #abb1 #abc ,sirius1 #ib 8skymarks10 #ib smallest meteorites1 #dh1 #abh see also dust1 meteoritic ,solar ,system1 #e1 #aaa1 #afd1 #age-f sounds made by falling meteorites1 #aa1 #ab1 #bd1 #be1bf1 #id-e1 #adh1 #aei space exploration and ships1 #e1 #afh1 #agj-f space-probes1 #agj-a space mining1 #afb1 #agd-f spectra and spectrograms1 meteor1 #ajg spectroscopy1 gamma-ray1 #aga speeds1 #ba1 #cb1 #ajg1 #ajh1 #aji1 #aaj-ab1 #abf1 #agb ,spencer1 ,l4 ,j41 #agi stainless steel1 #abj1 #abb1 #afg stones1 meteoritic1 #bh-cd1 #ce1 #gj1 #ga-b1 #gc-d1 #gh1 #hj1 #hb1 #aah1 #abj-d1 #abh1 #acj1 #aca1 #acb1 #acc1 #adh1 #aef-g1 #afc stony-irons1 #dj-a1 #aah1 #abb1 #abd1 #afc strata1 effect of impact on1 #dc1 #dd-e1 #dh-ea superstitions about meteors and meteorites1 #be1 #ef1 #hb1 #acd1 #acf1 #adg-eb1 #aed swarms1 meteorite1 #ej swarms1 meteor-particle1 #aaa1 #aab1 #aad ,swindel1 ,g4 ,w41 ,jr41 #agi 8swords from heaven10 #aej ,sylacauga stone1 #ga-b1 #gd1 #agi ,t taenite1 #abd tektite-obsidian test1 #ach-i tektites1 #acd-adf1 #afj tests for true meteorites1 #acj-c 8thumb-prints10 #aca1 #acb trajectory1 #ij1 #ib1 #agc tritium1 #agj ,tucson iron1 #abh ,tungus1 see ,podkamennaya ,tunguska twice-found meteorites1 #gf ,tycho1 lunar ray-crater1 #fa ,u ,university of ,california ,radiation ,laboratory1 #eh ,university of ,chicago1 #afh ,university of ,new ,mexico1 #bd1 #cj see also ,institute of ,meteoritics ,university of ,nebraska1 #cj1 #hj ,u4 ,s4 ,national ,museum1 #dj1 #aeh ,ussuri fall1 #aj1 #aa-cd1 #db1 #ej1 #ed1 #fe1 #acj ,v vaporization1 #ajb1 #ajg1 #aaf1 #abf1 #abh1 #adc1 #ade1 #afb1 #agb1 #agd velocity1 #ajg1 #ajh1 #aji1 #aga1 #agi ,venus1 #ajb1 #afb ,verbeek1 ,r4 ,d4 ,m41 #adj ,vienna1 ,national ,history ,museum of1 #da1 #aeh volcanic theories1 #ach1 #aee1 #aef1 #afd ,w ,wabar craters1 #ej1 #fe1 #adc1 #afb ,wasiutynski1 ,j41 #fc-d1 #agi water1 meteorites under1 #gh waves1 air and water1 #ab1 #ed-e weather1 effect of meteoritic dust on1 #aag weathering of meteorites1 #ch1 #dh1 #eb1 #ec1 #ed1 #ff1 #acc1 #add weights and weighing of meteorites1 #ce1 #cf1 #abh1 #acj ,white1 ,c4 ,s41 #agi ,widmansttten pattern1 #abj1 #aba1 #abb1 #aeh ,whipple1 ,f4 ,l41 #agg1 #agi ,willamette iron1 #cf1 #abh1 #abi ,wold ,cottage meteorite1 #aef ,wolf ,creek crater1 #eb1 #ec1 #fe1 #ge1 #acc ,y ,yale ,university1 #da young people and meteoritics1 #bc1 #bd1 #bh1 #cd1 #ci1 #ij1 #ih1 #ii1 #aaf see also reports1 eyewitness ,z ,zhovtnevy ,hutor fall1 #hb ,,footnotes #a;,also called aerolites4 #b,the meteorites from this crater-producing fall have been found in both ,haviland and ,brenham ,townships1 ,kiowa ,county1 ,kansas4 ,either of these names may therefore appear in the literature4 #c,the meteorites from this crater-producing fall have been found in both ,haviland and ,brenham ,townships1 ,kiowa ,county1 ,kansas4 ,either of these names may therefore appear in the literature4 #ddec4ei grams #a pound4 #e;,a questionnaire for making an adequate report is obtainable by request from the ,institute of ,meteoritics1 ,the ,university of ,new ,mexico1 ,albuquerque4 #f,readers who are advanced enough in astronomy to attempt plotting the meteor paths can get the proper star-maps and record sheets for this purpose by joining the ,american ,meteor ,society4 ,members must be at least #ah years old1 but applicants between #ad and #ah can become probational members4 ,for details write to ,dr4 ,c4 ,p4 ,olivier1 ,president1 ,american ,meteor ,society1 #eba ,north ,wynnewood ,avenue1 ,narberth1 ,pennsylvania4 #g,quite recently1 a fourth division1 the tektites 7discussed in the next chapter71 has been recognized by some authorities4 #h;,discussed in ,chapter #ab4 #i,the ,acts of the ,apostles1 #ai3ce4 #aj;,also baetyl and baetulus1 from the ,greek word baitylos1 a term used for sacred meteorites and stones4 #aa,this metallic mass was the first stony-iron meteorite to be identified as such4 ,the pallasites1 which make up an important subdivision of the stony-iron meteorites1 were named in honor of ,pallas4 #ab,very recently1 some authorities have concluded that there must have been not one but several meteorite-planets4 ,space ,nomads ,meteorites in ,sky1 ,field1 and ,laboratory ,by ,lincoln ,la,paz and ,jean ,la,paz ,meteorites are the real tokens of space6 ,they are samples of cosmic matter we can actually take in our hands4 ,science values them greatly as specimens of the only tangible substances we have from remote and inaccessible regions of the universe4 ,these mysterious 8space nomads0 are revealing to today's scientists many amazing and usable facts about conditions in outer space1 about the age of our ,solar ,system1 and even about the probable constitution of our own home planet4 ,this is an essential book for everybody who is keeping up with space science and wishes to be well posted on these interesting but potentially dangerous co-voyagers that the astronauts may encounter4 ,you will also see in ,,space ,,nomads3 ,the awesome event a meteorite-fall can be1 with its violent sound and light effects1 and its terrific impact4 ,the excitement and the know-how of the hunt for these cosmic missiles4 ,how to tell the difference between a true meteorite and a mistaken one4 ,ditto1 meteorite craters4 ,how to make your own contribution to science by knowing the right way to observe and report meteors and meteorites4 ,what is inside them1 and how they vary in content and structure4 ,the moon as a meteorite target4 ,the strange history of the subject--the amusing superstitions and fantastic notions believed until recently about 8shooting stars0 and 8stones falling from the sky40 ,and more4 ,here is an easy but sound introduction to the rapidly developing science of meteoritics4 ,all of the information is up-to-date1 much of it firsthand1 for the authors are themselves professional meteoriticists4 ,daily they are engaged in fieldwork1 laboratory analysis1 and advanced research at one of the world's chief centers for this study4 7,see back of jacket47 ,a ,,holiday ,,house ,,book #ab ,,up #c4ie ,jacket by ,leo ,manso ,illustration3 ,,harvey ,,caplin ,,photo ,lincoln ,la,paz ,on the moon is a ray-crater named ,la,paz in honor of the man who has had a major part in establishing the highly significant theory that the lunar ray-craters were made by the impact of meteorites4 ,lincoln ,la,paz is a leading pioneer as well as a widely recognized authority in meteoritics1 an important branch of astronomy4 ,he was born on ,lincoln's birthday1 in ,wichita1 ,kansas1 where he grew up4 ,although both his master's degree1 at ,harvard1 and his doctorate1 at ,chicago1 were in mathematics1 his chief interest since boyhood has been in meteorites and meteors4 ,today he is ,director of the ,institute of ,meteoritics at the ,university of ,new ,mexico1 where he also heads the ,division of ,astronomy4 ,illustration3 ,,ravini ,,photo ,jean ,la,paz ,jean ,la,paz was born in ,hanover1 ,new ,hampshire4 ,since girlhood she has been close to her father in his fascinating work4 ,when she was a high-school student in ,ohio1 she did some serious fieldwork as a member of the ,ohio ,state ,university ,meteorite ,expeditions4 ,later1 she received both a ,bachelor of ,science degree in geology and a ,master of ,arts in ,english from the ,university of ,new ,mexico4 ,science and ,literature continue to be her mutually favoring interests4 ,transcriber's ,notes --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,silently corrected a few palpable typos4 --,in the text versions only1 text in italics is delimited by underscores4