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                                                           LINCOLN LAPAZ
                                                          AND JEAN LAPAZ




                                 SPACE
                                 NOMADS
                           METEORITES IN SKY,
                          FIELD, & LABORATORY


                        HOLIDAY HOUSE, NEW YORK

                          COPYRIGHT, 1961, BY LINCOLN LaPAZ & JEAN LaPAZ
                                                   PRINTED IN THE U.S.A.

    [Illustration:        COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Fireball speeding across field of camera during the photographing
    of the Great Spiral Nebula in Andromeda, by Josef Klepesta, at the
    Prague Observatory, Czechoslovakia, September 12, 1923.]




                                PREFACE


Meteoritics is the study of the only tangible entities that reach us
from outer space. Except for the meteorites, 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 earth. And
none of the radiations reaching us from various sources afar can be held
in the hand for examination. 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 galaxies, or the reflected light from the planets
and moons of our Solar System, or the less familiar forms of radiation,
such as radio waves and cosmic rays—must be measured and permanently
recorded by complicated instruments. Often the results given by even the
most sensitive and tractable of these scientific robots turn out to be
exceedingly difficult for man, their master, to interpret.

But the meteorites require no such temperamental instruments for their
measurement. They are themselves a permanent record. They can be
weighed, sectioned, and polished. They can be studied chemically,
microscopically, and radiometrically. In fact, they can be investigated
_directly_, just as they are themselves, in our hands, by any method
modern science may be clever enough to devise.

This is why, now with the world’s attention drawn to ambitious plans for
the exploration of the cosmos, meteors and meteorites are of increasing
interest and importance.

We have planned and written this book to be a sound and yet largely
nontechnical introduction to the science of meteoritics. Our daily
experiences in the Institute of Meteoritics have afforded us a fortunate
advantage in making such a presentation. For, in addition to our work in
the field, laboratory, and classrooms, 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 ours. We hope our book will instill in the
reader an abiding interest in the location and protection, the recovery
and preservation and especially in the study of those cosmic missiles of
iron, iron-stone, or stony composition that represent mankind’s only
ponderable links with the vast universe lying beyond the limits of the
earth’s atmosphere.

Although all photographs and special depictions not made by our staff
are individually credited, we wish to express our personal thanks for
the privilege of reprinting them here. All photographs that are without
a credit line have been made by members of our staff.

_Lincoln LaPaz_    _Jean LaPaz__University of New Mexico, Albuquerque,
March 20, 1961_




                           TABLE OF CONTENTS


    PREFACE                                                            5
  1. A METEORITE FALLS IN THE TAIGA, U.S.S.R.                         11
  2. A METEORITE FALLS IN THE WHEATLAND, U.S.A.                       23
  3. FOUND AND LOST GIANTS                                            36
  4. WHEN IS A CRATER A METEORITE CRATER?                             42
  5. HEAVEN KNOWS WHERE OR WHEN                                       66
  6. FINDERS FOOLISH, FINDERS WISE                                    75
  7. LANDMARKS, SKYMARKS, & DETECTORS                                 84
  8. THE NATURE OF METEORS                                           101
  9. THE NATURE OF METEORITES                                        118
  10. TEKTITES, IMPACTITES, & “FOSSIL” METEORITES                    134
  11. OMENS AND FANTASIES                                            147
  12. THE MODERN VIEW                                                158
  13. PRESENT AND FUTURE APPLICATIONS                                166
    FOR FURTHER READING                                              177
    INDEX                                                            181




                               SPACE NOMADS
                  METEORITES IN SKY, FIELD, & LABORATORY


    [Illustration: Painting of the Ussuri fireball by the Iman artist,
    P. I. Medvedev.]




              1. A METEORITE FALLS IN THE TAIGA, U.S.S.R.


The morning of February 12, 1947, dawned cold but bright and sunny in
the wide Ussuri valley of Eastern Siberia. During the early morning
hours the people in the villages went about their everyday chores as
usual. Farmers fed and watered their livestock, while housewives tidied
rooms and fired up stoves for heating and baking. Miners went to work
deep underground. An artist seated himself outdoors near his home to
make exercise sketches. In a densely wooded area on the slopes of a
nearby mountain range, a logging crew began a day’s timber-cutting.

Suddenly, at 10:35 a.m., an extraordinarily large and brilliant fireball
flashed above the central part of the mountain range. It streaked across
the sky in less than 5 seconds and disappeared beyond the western
foothills of the range. Then the inhabitants of a wide area heard what
seemed to them a mighty thunderclap followed by a powerful roar like an
artillery cannonade. Many people felt a strong airwave. (Field parties
later found that those who noticed this effect were quite close to the
place where the meteorite fell.)

For several hours afterward, a large black column of smoke tinged with a
reddish-rose color stood above the place of fall. Gradually, this cloud
spread outward, became curved and then zigzag in form, and finally
vanished toward the end of the day.

The flash of the fireball and the loud noises that followed it caused
panic among the farm animals. Cows lowed mournfully and herds of goats
scattered in every direction, chickens and other fowl squawked in alarm,
and dogs ran whining for shelter or crouched against the legs of their
masters.

In the villages, the airwave blew snow off the roofs of houses and other
buildings, while the strong earth-shocks opened windows and made doors
swing ajar. Housewives were dismayed to see glass windowpanes shattered
in their frames and burning coals and firebrands jolted out of the
wood-burning stoves.

Even deep in the mineshaft, the vibrations in the air were strong enough
to snuff out the miners’ lamps, leaving the men in darkness.

On seeing the huge fireball streak across the sky, the artist put aside
his practice sketch and began a picture of the display before his
impressions of it could fade. His painting of this natural event is now
famous. Not only is it on display in scientific museums all around the
world, but a color reproduction of it has been issued in Russia as a
postage stamp.

The forester supervising the logging crew reported that his attention
was first attracted to the sky when he noticed a strange “second” shadow
rotating rapidly about the tree that cast it. On looking up, he saw a
blindingly bright fireball, twice as large as the sun, a fiery globe
that threw off multicolored sparks as it passed. Not long after the
fireball disappeared behind the trees, 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 point. (The members of the logging
crew were among the very few persons actually abroad near the place of
fall. It turned out that they were only about 9 miles from it.)

As soon as the many eyewitnesses of the fireball had recovered from
their fright, the questions almost everyone asked were “What could it
have been?” and “Where did it come down?” To answer the first question
was not as difficult as to answer the second. Local scientists in
Vladivostok and Khabarovsk, the nearest cities of some size, suspected
from the first that a very large meteorite fall had occurred. But
exactly where? All they could be certain of was that the impact point
lay in the Ussuri taiga, a formidable wilderness.

The Sikhote-Alin mountains lie along the Siberian coast between the Sea
of Japan and the Tatar Strait. The Ussuri taiga is a vast, low-lying,
marshy, densely forested region fronting the western flanks of these
mountains. Ordinary cedars, pines, oaks, and aspen grow in the taiga,
but the region is also noted for such rare plants and trees as the
celebrated ginseng, the cork tree, the Greek nut tree, and the black
birch. Wild grape and ivy vines intertwine the upper branches of the
thick forest, and the trunks of the trees themselves rise from an almost
impenetrable maze of brush and downed timber.

So dense is the forest that in summer, a man can see no more than 10 or
12 feet in any direction. Yet in winter, the explorer’s lot is no
easier; for, although the deciduous trees then stand leafless, the
ground is covered by three feet or more of snow. And in the early fall,
violent cloudbursts often flood the taiga, making travel impossible.

Such was the inhospitable region in which the Ussuri, or (as it is now
known in the U.S.S.R.) Sikhote-Alin meteorite, had chanced to fall. For
any search parties traveling on the ground, the likelihood that they
could find the fallen meteorite in that wilderness would have been very
small.

The impact point of the Ussuri meteorite was discovered in the only way
really practical: from the air. Fortunately, the center of impact lay
almost directly below the airlane connecting the towns of Iman and
Ulunga, so that the devastation produced by the meteorite fall in the
taiga was clearly visible to aviators following this active air route.

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 parties, one at Khabarovsk,
the other at Vladivostok. The Khabarovsk group, made up of four members
of the Geological Society, flew to the village of Kharkovo, the
inhabited point nearest the site of fall. After a rough and dangerous
landing on the small, snow-covered airfield at Kharkovo, the geologists
began their trek into the taiga on foot. Throughout the entire trip, the
men, burdened with supplies and equipment, waded through waist-deep snow
and camped in the open despite the arctic cold.

At almost the same time, a geologist from Vladivostok set out from the
railway line up the Ussuri valley to track down the fallen meteorite.
His progress was even more difficult than that of the Khabarovsk party.
In addition to following a much longer route, he did not have the
invaluable information that the first party had got from the aviators.
He had to make his way slowly from village to village, questioning
eyewitnesses as he went and gradually determining the probable end-point
of the meteorite fall.

    [Illustration:                              COURTESY OF E. L. KRINOV
     Splintered and broken trees at the site of the Ussuri fall.]

The route followed by the Vladivostok geologist lay through the heart of
the trackless snow-covered taiga. Fortunately, 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 land.

They slept in hunters’ huts or under overhanging trees, drank melted
snow water, and ate fried quail. But they had not gone far when they
found that their footwear was completely useless for a trek through the
wet, snowy taiga, because their felt hiking boots quickly soaked up
water and became very heavy. So they swathed their feet in warm dry
grass over which they tied large pieces of untanned leather. After that,
the walking was much easier. 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 airfield.

At Kharkovo, the three feasted on pork, milk, and honey. Then loading a
few provisions on a borrowed horse, they started out to overtake the
Khabarovsk party. They made such good time that the two groups were able
to join forces and to enter the impact area as one expedition, on
February 24, 1947.

A scene of great desolation awaited them in the central region of the
meteorite fall. Masses of crushed stone had been hurled hundreds of feet
by the violent impact. Denuded, uprooted trees lay about—some cut in two
as neatly as if by a saw. Large cedars had been splintered where they
stood or had been torn up by the roots and thrown some scores of yards.

    [Illustration:                              COURTESY OF E. L. KRINOV
     Workmen excavating one of the large craters formed by the impact of
    the Ussuri meteorites.]

Most impressive of all, though, were the numerous meteorite craters
ranging in size from small bowl-like features to a basin more than 28
yards across and over 6 yards deep—a depression large enough to hold a
two-story house. 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 “shrapnel.”

With their meteorite recoveries and photographs of the cratered area,
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 U.S.S.R. in making a full-scale
investigation of the Ussuri fall. The officials of the Academy decided
at once to send a special scientific expedition to the site of the
meteorite fall.

A member of this later and better-equipped expedition compared the
Ussuri crater field to a bombed-out area. In fact, some of the meteorite
specimens were fragments that closely resembled pieces of shattered
shell-casing. The edges of these fragments were jagged and bent, and
their surfaces, which often displayed a rainbow-colored sheen, were
grooved and scarred by impact against the hard rock underlying the
region in which the crater field had been formed. In rare instances, the
investigators noted spiral twisting of the fragments, an indication of
the unusually violent disruptive forces to which they had been subjected
at impact.

The scientists found several instances in which fist-sized meteorite
fragments had actually penetrated into or through standing tree trunks,
either becoming imbedded in the wood or driving a hole right through the
trunk.

    [Illustration:                              COURTESY OF E. L. KRINOV
     A nickel-iron meteorite from the Ussuri fall imbedded in the trunk
    of a cedar tree.]

Many whole individual meteorites also were recovered. These were almost
always covered by a thin, smooth “glaze” known as _fusion crust_. This
crust forms on the surface of a meteorite as it plunges rapidly through
the air. The heat generated during its flight causes the outer “skin” of
the meteorite to melt. Later, when the mass has cooled off, the thin
coating of melted material hardens, forming a rind or crust.

By the beginning of 1951, the Russians had sent three more expeditions
to the site of the Ussuri fall. Their scientists found, in all, 122
craters (the largest more than 80 feet in diameter) as well as numerous
funnels resulting from the penetration of smaller meteorites into the
earth. By means of both visual and instrumental searches, they also
recovered 20,000 meteoritic fragments and individual meteorites. The
smallest Ussuri specimens weighed no more than the thousandth part of a
gram. (There are 453.59 grams in a pound.) Some of these tiny masses
were found lying cupped in leaves. The largest individual meteorite
recovered weighed about 3,839 pounds. Altogether, approximately 23 tons
of meteoritic material from the Ussuri fall are now in the collection of
the Meteorite Committee of the Academy of Sciences, Moscow, while
another 47 tons are believed to still be buried in the Ussuri crater
field.

    [Illustration:                              COURTESY OF E. L. KRINOV
     An individual Ussuri meteorite with fusion crust and characteristic
    surface sculpturing produced during high-speed flight through the
    resisting atmosphere.]

The Russian scientists carefully mapped the locations of the individual
craters, penetration funnels, and meteorite recoveries. They made
geologic and magnetometric surveys of the crater field, took aerial
photographs of the entire area of fall, and prepared a documentary
motion-picture covering the activities of the various expeditions. The
area of the crater field has been set aside by the Russian government as
a sort of scientific preserve, and is being made into the equivalent of
what is termed a National Monument in the U.S.A. Several of the typical
craters are protected by overroofed shelters to preserve these features
for generations yet to come.




             2. A METEORITE FALLS IN THE WHEATLAND, U.S.A.


February 18, 1948, had been a pleasant day in northwestern Kansas and as
the supper hour approached, the sky remained blue and cloudless. Shortly
before 5:00 p.m., a few people were still out of doors. An eleven-year
old girl was hanging up the last of the family wash on a high
clothesline. In the late afternoon sunshine, a woman and her son were
enjoying a walk around the back yard of their home on a large Kansas
ranch. Outside his house, a ten-year old boy was playing basketball with
friends. A veteran of World War II was loading fodder in a silo. In the
feedlot of his ranch, a farmer was stacking hay. A filling station
attendant was working outside at the pumps, grateful for a spell of
milder winter weather.

Without warning, a large and very bright fireball streaked across the
clear sky from southwest to northeast. Ominous-looking white
smoke-clouds mushroomed up from points in the fireball’s path. Shortly
after the fireball disappeared, loud explosions and rumbling sounds
drove thousands of people out into the open. The whole astonishing
luminous display was over in a few seconds, but the strange clouds and
the frightening sounds that followed the fireball’s passage continued
much longer.

Although startled by the brilliant fireball and the strange thundering
noises, the young girl, whose face had been turned skyward as she hung
up the clothes, noted very carefully where she had seen the fireball
disappear behind the tallest building in her home town. (Her sighting
was later of great value to field parties from the Institute of
Meteoritics of the University of New Mexico.)

The woman and her son were amazed to see an angry, boiling white cloud
tinged with red developing overhead in the blue sky and to hear strange
whizzing noises in the air around them.

The boy playing basketball heard a peculiar whistling or hissing noise
just as he was ready to shoot a basket and, on looking up, saw the ball
of fire slanting earthward. (This boy’s report was of particular
interest, since it related to an unusual type of “sound” that travels at
the speed of light rather than at the velocity of ordinary soundwaves.)

As a cannonading louder than any the veteran had heard on the
battlefields of Europe echoed over the rolling countryside, he went
temporarily into a state of shock.

The farmer stacking hay heard several explosions, felt a violent air
blast, and finally heard a solid object strike the ground “with a
smack,” as he put it, “like a clod hitting the earth.” (Later, 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 fell.)

Shortly after the passage of the fireball, the filling station attendant
felt the legs of his trousers flap as if he were standing in a high
wind, although he was more than 11 miles distant from the actual path
along which the fireball moved on its way to the earth.

As in the case of the Ussuri fall, which had occurred about a year
earlier, farm animals, chickens, and dogs were terrified by the strange
and noisy event. Cattle tried to run through a fence to escape the
deafening racket. A fine pair of horses panicked and ran headlong into a
narrow gully, the walls of which collapsed on them during their
struggles. Chickens dashed for the henhouse, screeching and cackling all
the way. A dog that feared lightning jumped behind a haystack and
finally ran to his master in alarm.

Although the majority of the people did not see the fireball itself,
they were driven out-of-doors by the violent concussions that followed
its passage, and thus got out under the open sky in ample time to see
several large, turbulent white clouds mushrooming far overhead. From
these clouds, a thick powder or dust filtered down through the air and
collected on the surfaces of stock ponds and water tanks.

Some people thought the peculiar clouds were similar to those produced
by atom bomb explosions. Many suspected that a V-2 rocket had “run away”
from the proving ground at White Sands, New Mexico. One man disagreed
with the opinion of his friends that the military had been experimenting
and declared that it was “the Lord who was experimenting!”

The February 18 meteorite fall caused great excitement throughout Kansas
and Nebraska, 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 line.

The Ussuri fall was studied by Russian scientists exclusively, and we
have of necessity given, in Chapter 1, a secondhand account of the fall
and surveys the Russians made; but field parties from the Institute of
Meteoritics conducted on-the-spot investigations of the Norton, Kansas
fall. As we were members of several of these field parties, the story to
follow is a firsthand report.

A little before 6:00 p.m. on February 18, word of the mysterious
explosion centering near Norton, Kansas reached the Institute of
Meteoritics, in Albuquerque, N. M., through the kind offices of Civil
Air Patrol personnel. Since a number of early reports had described the
incident as an airplane falling in flames, it was only natural that the
Civil Air Patrol and similar groups would take an interest in the
occurrence. At once, the staff of the Institute began to interview
eyewitnesses of the event through Civil Air Patrol channels and by long
distance telephone, telegram, and letter. 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 Kansas, Nebraska, and adjoining states.

By March 3, the Institute staff had made a first determination of the
probable area of fall. The center of this oval-shaped, 8 by 4 mile area
lay about 15 miles north-northwest of Norton, Kansas and nearly on the
Kansas-Nebraska state line. The meteorite had fallen in a region of
wheat fields, pasture lands, and widely scattered farm houses. The
countryside there is open and gently rolling. The small creeks winding
through shallow valleys are marked in spring and summer by narrow bands
of low green trees and bushes. Many of the hillsides are covered with
unplowed buffalo sod.

    [Illustration: A fragment of the Norton fall is removed still
    imbedded in the tough buffalo grass sod into which it penetrated.]

On March 24, a field party left the University of New Mexico to make a
survey of this area. Unfortunately, Kansas blizzards can be as severe as
any in Siberia, and although the scientists gathered many helpful
reports from eyewitnesses of the fall, heavy snow and high winds
seriously hampered the work. The information they collected, however,
confirmed the accuracy of the Institute staff’s first determination of
the probable area of fall.

Late in the spring, a farmer in this area found a “strange stone” on his
land and held it for identification by the second Institute party. This
strange stone—which smelled like sulfur and had metallic specks in
it—was the first piece of the fallen meteorite to be recovered.

Scientists and farmers soon found many other fragments during systematic
searches of the rolling farm and pasture lands. The fourteen-year-old
boy who had been walking with his mother at the time of the fall
discovered a 130-pound fragment of the meteorite in a pasture that had
already been carefully searched by grown-up meteorite hunters! This find
was one of the two largest fragments recovered from the entire fall. The
landing place of this large piece was marked only by a small hole in the
sod, but, on prodding into this hole, the boy struck something rather
solid. He ran at once to tell the lady who owned the pastureland, and
together they dug out the fine meteorite.

    [Illustration: The Furnas County, Nebraska, stony meteorite in place
    at the bottom of its 10-foot “penetration funnel.”]

This discovery brought interest in finding meteorites to a fever pitch,
and it was soon possible to look in almost any direction and see
farmers, or their wives and children, walking slowly across the fields
and looking for meteorites.

Finally, in August, 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 it. They investigated and discovered that
a very large fragment of the meteorite had buried itself deep in the
ground.

Scientists from the University of Nebraska and the Institute of
Meteoritics carefully excavated this huge meteorite. They found that the
mass had plunged more than 10 feet into the earth. Quite by chance, its
lower surface had come to rest in the ashes of a long-buried primitive
cooking site.

The excavated meteorite looked and felt like a huge stone. Actually, it
was stony in nature, but of a texture so fragile that it had to be
wrapped in tissue paper, then in burlap, and finally covered with a
thick coating of plaster of Paris before it could be lifted out of the
ground. Those in charge of the removal of the meteorite borrowed this
procedure from the paleontologists, who use it in the removal of fossil
tusks and bones that otherwise would crumble away.

After the great meteorite had been raised out of the excavation, it was
taken by truck to the University of New Mexico, in Albuquerque. There it
was put on display beside the smaller 130-pound fragment found in May.
By careful measurements, scientists determined the weight of the main
mass to be approximately 2,360 pounds—a record weight for stony
meteorites.[1] This remarkable meteorite, known as the Furnas County,
Nebraska, stone, is now a prized item in the collection of the Institute
of Meteoritics.

    [Illustration: Field party proudly surrounds the Furnas stone in its
    protective “armor.”]

As more and more finds were made in the area of fall, we accurately
recorded their weights and mapped their locations. In this way, we could
tell how the pieces of the meteorite had distributed themselves
according to size and weight over the oval-shaped area. The smaller and
lighter fragments were slowed down by air resistance and fell first,
while the 2,360-pound mass carried on beyond them and came to earth at
the farthest point along the direction of flight.

The staff of the Institute took many photographs of the meteorites that
were found, of the impact funnel made by the largest mass, and of the
excavation and removal of that giant stone. Some of these pictures were
published in scientific journals, others in magazine and newspaper
articles. A few of our best photographs are included in this chapter.

Although the light and sound effects that accompanied the Ussuri and
Norton falls were similar, the meteorites recovered from them were not
at all alike. 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 shapes. But the Norton meteorites
were very fragile stony masses, many of which went to pieces either in
the air or when they struck the ground. Almost all of the recoveries
made of this very rare type of stony meteorite were fragments, not whole
specimens. They somewhat resembled pieces of a strange whitish mixture
of chalk and crystalline limestone containing tiny specks and lumps of
nickel-iron. Many specimens were covered wholly or in part by a shiny
varnish-like fusion crust, varying in color from jet black through
yellow to almost pure white.

    [Illustration: The Furnas stone, protected by its “armor,” hangs
    suspended from the truck crane that raised it out of its deep
    “penetration funnel” in the earth.]

The largest meteorite recovered from the Norton fall was the 2,360-pound
mass that formed the deep impact funnel. The smallest Norton specimens,
like their Ussuri counterparts, weighed no more than the thousandth part
of a gram. Altogether, nearly a ton and a half of meteoritic material
from the Norton fall was collected by the Institute. Other small
fragments may remain undiscovered in the Kansas and Nebraska wheatlands,
but, unfortunately, because of the soft and fragile nature of the
material they are composed of, it is likely that they have now weathered
away so completely that they are no longer recognizable as meteorites.

Our stories of the Ussuri and Norton meteorite falls show how hard
scientists work themselves (and others!) to find meteorites. Therefore
meteorites must be important. The two accounts given also make clear
that investigators of meteorite falls are almost entirely dependent upon
observations made by nonscientists.

Scientists investigating meteorite falls greatly appreciate the help
given them by children and adults alike. Field parties are powerless
without it, and we should like to encourage people of all ages to
continue this type of valuable cooperation. In Chapter 7, we shall tell
more about how the individual observer of a meteorite fall can make his
report really count.

    [Illustration: A close-up of the Furnas County stone, the largest
    stony meteorite ever recovered.]




                        3. FOUND AND LOST GIANTS


All meteorites are important from the standpoint of science, but a few
deserve special mention because of the human-interest stories connected
with them.

First place among famous finds should no doubt go to the massive Cape
York, Greenland, iron, the largest recovered meteorite actually to have
been weighed. The Eskimos called this enormous object “Ahnighito,” which
means “The Tent.” Robert E. Peary, the discoverer of the North Pole,
brought it to New York City by ship in 1897. His party had great
difficulty hoisting the 34-ton mass aboard. Later, when the ship had put
to sea, she encountered a serious navigational hazard. To the amazement
and alarm of the crew, the huge nickel-iron meteorite caused magnetic
disturbances that severely affected the ship’s compass.

Another of the giant meteorites, the 14-ton Willamette, Oregon, iron,
became the center of a long legal battle in the early 1900’s. 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 (as the ore of a metal would have been), there was no reason
why he should not move the mass from the place of find to his own
property, three-fourths of a mile away. He did this very laboriously by
means of a log-timber car, a capstan with wire rope, and a small horse.
On learning what the finder had done, the company that owned the land
from which the meteorite had been removed put its attorneys on the job
of recovering the “purloined” meteorite. The Oregon courts, bowing to
decisions made in previous cases involving ownership of meteorites,
brought in a verdict favoring the owners of the land. Although the
finder of the Willamette meteorite lost the decision, he nevertheless
won the distinction of being the only man to have successfully made off
with a treasure weighing 14 tons!

    [Illustration:        COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Peary’s photograph of the Cape York meteorite as it was being moved
    for loading aboard his ship.]

    [Illustration:        COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Arrival of the 34-ton iron mass at the American Museum of Natural
    History, New York City.]

The biggest meteorite of all, of course, is the one that “got away.” In
1916, a captain in the Mauritanian army was taken by a native guide,
secretly and at night, to the site of a colossal iron meteorite located
in the dunes of the Adrar desert, in the far western reaches of the vast
Sahara. The officer described the mass as measuring 100 meters (over 300
feet) by 40 meters (over 120 feet), with the third dimension hidden by
the sand dunes. According to him, the mass “... jutted up in the midst
of sand dunes that were covered by a desert plant, the _sba_, and it had
the form of a compact, unfissured parallelopiped. The visible portion of
the surface was vertical, dominating in the manner of a cliff, the
wind-blown sand that was scooped away from the base of the mass so that
the summit overhung; and that portion exposed to eolian [wind] erosion
was polished like a mirror.”

The captain, at the request of his uneasy guide, returned from his
hurried excursion without taking notes or making a map. But he did bring
back a small 10-pound fragment of iron which he had found lying on top
of the giant mass. This small fragment later proved to be a genuine
meteorite, and is the only known specimen of the famous Adrar mass. It
is preserved at present in the Museum of Natural History at Paris.

    [Illustration:                                J. OTIS WHEELOCK PHOTO
                          COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Man and boy carrying off the famous “purloined” Willamette
    meteorite on a homemade dolly car with wheels of tree-trunk
    sections. Note hole piercing this 14-ton chunk of iron.]

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 captain. The native guide died,
apparently of poison, and although many inhabitants of the region are no
doubt familiar with the whereabouts of the mass (whatever it is!), those
questioned have consistently denied knowledge of its very existence. All
recent attempts, not only by military but even by scientific
expeditions, to relocate the gigantic metallic mass have failed. The
whole Adrar case remains an intriguing puzzle to be unraveled, it is
hoped, by future generations of meteorite hunters.

Another “lost” meteorite is one composed of stone and iron. The Port
Orford, Oregon, stony-iron (as it is now named) was originally found in
1859 by a U.S. geologist who was engaged in a survey of what were then
the Oregon and Washington Territories. According to him, the mass was
quite irregular in shape and “4 or 5 feet [of it] projected from the
surface of the mountain,” while it was “about the same number of feet in
width and perhaps 3 or 4 feet in thickness.” He broke off a small
fragment of it (far smaller than the one taken from Adrar) and packed
this specimen away with his collection of rock and mineral samples.
Years later, the geological collection was cataloged and analyzed in the
East. At that time, the fragment collected in 1859 was found to be a
piece of a stony-iron meteorite. After that, scientists and others made
many attempts to rediscover the main mass of the large Port Orford
meteorite, all of them unsuccessful. Today the sum total of material
recovered from this stony-iron amounts to 25 grams in the U.S. National
Museum, about 4 grams in the Natural History Museum of Vienna, and a few
tiny specks in the Museum of the Geological Survey of India.

The Red River, Texas, iron is still another famous meteorite. It was
originally discovered by Pawnee and Hietan Indians, and a group of them
took a party of traders, in 1808, to the site. Two years later, two
rival parties, each led by a man who had been a member of the 1808
trading expedition, began a search for the meteorite. The members of one
of the two parties were from Nacogodoches, Texas. 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 mass. They went away
from the site to get horses and a wagon, after they had laboriously
hidden the meteorite under a huge flat stone, to prevent the other party
from finding it. The members of the other party, hailing from
Natchitoches, Louisiana, set out better prepared. After a lengthy hunt,
they finally found the hidden meteorite. Using tools they had the
foresight to bring, they built a truck wagon and drove away with their
prize. Eventually, the Red River meteorite, weighing 1,635 pounds,
became a part of the collection at Yale University. But two other,
smaller, masses of the same metal, known in the early days to the
Pawnees and a few traders, remain still undiscovered in the Red River
area.




                4. WHEN IS A CRATER A METEORITE CRATER?


Not all meteorites form craters at impact, as the larger Ussuri
fragments did. Even the largest mass of the Norton meteorite merely
buried itself in a funnel-like hole only about 10 feet deep. And the
Russian investigators found a number of the lighter Ussuri fragments at
the bottom of small penetration funnels. Cosmic missiles that are large
enough to blast out craters in the ground are of particular interest to
science, however, not only because of the extraordinarily intense light,
sound, and other effects that accompany their fall, but also because
they produce characteristic and long-lasting basin-like features in the
outer shell of the earth.

Natural processes that change the surface features of the earth have
long been the subjects of field studies by scientists. Geologists have
carefully investigated the major folds formed in the earth’s crust by
mountain-building forces, the clefts and depressions resulting from
earthquake activity and erosion, and the vast plains leveled off by the
scouring action of great ice-sheets. All of these different natural
processes, though, have one thing in common: their source is the
earth-body itself. They take place either _within_ the earth’s crust as
a result of local shifts or changes in pressure (like earthquakes and
volcanic eruptions), or _on_ the surface of the earth as a result of the
action of water or of changes in temperature (like erosion and
glaciation).

On the other hand, meteorite impact craters are not formed by
earth-processes at all. As we have seen, 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 speed. The study of meteorite craters
is therefore a special field. It is also one of quite recent
development; not until 1905 was the first meteorite crater recognized as
such.

The first thing to be said on this subject is, of course, that not all
holes in the ground, however large and impressive, were necessarily
formed by the impact of meteorites. Features that resemble meteorite
craters may result from certain ordinary earth-processes. For example,
the rock layers underlying a particular area may be dissolved away by
waters circulating beneath the surface of the ground. The overlying
crust will eventually collapse into the empty space, and what geologists
call a “sink hole” or a “sink” is formed. Many such sinks surround the
genuine meteorite crater near Odessa, Texas, and at times have been
mistaken for the real thing.

Since there is some possibility of confusion about whether or not a hole
in the ground is a meteorite crater, it is comforting to know that
scientists have come up with a handy set of rules for reaching a
decision on this point. These rules can be stated in the form of several
questions that crater-investigators should ask themselves:

  Have you found meteorites in or near the crater-like feature?

  In its vicinity, have you found pieces of country rock that show the
  effects of high temperature and pressure (melting or crushing)?

  Did people actually see a meteorite come to earth at the point where
  the crater is located and where, to their certain knowledge, no crater
  existed before?

If the answer to all—or even one—of these questions is yes, then it is
quite likely that the crater-like feature is actually a meteorite
crater. Naturally, if the answer to the _first_ question is yes, the
matter is practically settled in favor of the meteoritic origin of the
feature.

If the impact has taken place in horizontally bedded rock strata—that
is, 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 layers. (None of the ordinary
sink holes near the Odessa crater show such rims.) In addition, pieces
of rock shattered and thrown out by the impact will be found in all
directions around the crater. The amount and size of this fragmented
material will decrease with distance outward from the crater.

A list of the recognized (or genuine) meteorite craters of the world is
given in the table on page 65. All of these craters except the two
Russian ones were formed many thousands of years ago, and, in most
cases, 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 remain.

    [Illustration: Cross-section showing the manner in which
    horizontally bedded rock strata may be broken and tilted upward by
    the impact of a crater-forming meteorite. This schematic diagram is
    based on excavations at several meteorite craters.]

You may have visited the very first crater in the world to be recognized
by scientists as a meteorite crater. This huge basin, now known as the
Canyon Diablo meteorite crater (although often referred to incorrectly
as “Meteor Crater”), lies about 20 miles west of Winslow, Arizona. 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 U.S. Highway 66.

From the paved road that turns off Highway 66 toward the crater, the
visitor sees the rim as a chain of low, hummocky, tan-colored hills
which contrast sharply with the grayish or reddish hue of the desert
plain.

The outer slopes of the crater rim rise very gently from the level plain
in which the crater was formed, and they are covered with rock fragments
of various sizes thrown out at the time the meteorite struck the earth.
This fragmented material ranges in size from tiny particles of
“rock-flour” as soft as face-powder to gigantic solid masses like
Monument Rock, which is estimated to weigh 4,000 tons.

Field parties have found 50- to 100-pound fragments of the limestone
layer underlying the Canyon Diablo area at distances of 1½ to 2 miles
from the crater. Sizable rock and meteorite fragments out to distances
of 6 miles from the rim have turned up, and smaller fragments of both
materials at even greater distances.

On their first visit to the Canyon Diablo crater, people are always
astonished at the steepness of the inner walls of the crater and at the
very great size of its bowl. This crater is more than 4,000 feet across
and 570 feet deep. It is the largest _recognized_ meteorite crater so
far discovered in the world, although other larger, basin-like features
elsewhere on the surface of the earth have been suspected but not proved
to have a similar origin.

    [Illustration:                      COURTESY OF TRANS-WORLD AIRLINES
     Aerial view of the Canyon Diablo, Arizona, meteorite crater.]

When the Canyon Diablo meteorite plunged into the horizontally bedded
rock layers underlying the area of fall, the force of the explosion
following the impact actually bent these layers upward. All around the
inside of the crater, the rock strata tilt away from the center at steep
angles.

Cowboys, ranchers, and scientists have found thousands of solid
nickel-iron meteorite fragments around the crater. The largest of these
weighs 1,406 pounds. The smallest spherules and grains are almost or
quite microscopic in size. (These tiny granules have been well known to
scientists since 1905 in spite of current fables claiming that they are
a recent discovery.) In the rim and on the plain outside the crater,
large and small _shale balls_, composed of weathered meteoritic
material, were found in considerable numbers in the early days. Along
with many solid iron meteorites, shale balls have also been found at
various depths in recent times by field parties from the Institute
employing specially designed meteorite detectors.

In the first two decades of the twentieth century, investigators sank
(at great expense!) a number of shafts and drill holes in the interior
and on the south rim of the crater, in unsuccessful attempts to locate
the supposed “main mass” of the Canyon Diablo meteorite. Most
authorities now believe, however, that the extremely high temperatures,
developed at the time the Canyon Diablo meteorite penetrated into the
earth, changed almost all of the gigantic cosmic missile into vapor.

    [Illustration: View of the interior of the Canyon Diablo crater
    showing the steep inner slopes of the huge basin.]

No better example of an ancient meteorite crater has been found than
this one near Canyon Diablo. The other craters listed in the table (even
the two recently formed ones), while bearing resemblances to it, also
show individual differences from it.

Some, like Henbury, Campo del Cielo, and Haviland, are not single
craters but rather consist of fields of craters. In these cases, the
earth was struck not by a single large meteoritic body that held
together right down to impact, but either by a “swarm” 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 ground.

Again, the type of ground into which the meteorite strikes affects the
character of the craters formed. As an illustration, the Wabar, Arabia,
craters were not smashed out of sedimentary, horizontally bedded rock
layers (as was the Canyon Diablo crater) but were formed in clean desert
sand dunes. In this case, the crater rims are composed primarily of
almost pure silica-glass formed by the fusion of the sand at the time of
impact. 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 craters.

Except for Podkamennaya Tunguska and Ussuri, the craters listed in the
table were formed, as we have mentioned, a great many thousands of years
in the past. Just how many thousands is a difficult question to answer,
for all of our estimates must necessarily be made on the basis of
_indirect_ evidence rather than on _direct_ observation.

    [Illustration: Before impact of Canyon Diablo meteorite, these rock
    layers were horizontal.]

Paleontologists, geologists, and other scientists give us an age of from
20,000 to 70,000 years for the Canyon Diablo crater. The discovery of
the fossil remains of a prehistoric horse buried in the Odessa, Texas,
crater fill has shown that the age of that crater is not less than
200,000 years. The oldest craters known in the United States are the
Haviland group produced by the Brenham, Kansas, meteorites.
Long-continued weathering has almost completely worn down the rims and
covered up the craters of this group. On the basis of the rate at which
nickel-oxide has spread out into the soil about a large deeply buried
Brenham meteorite, calculations carried out at the Institute of
Meteoritics have led to a tentative age of more than 600,000 years for
the Kansas craters.

Perhaps the oldest meteorite crater of all is the one blasted into what
the geologists identify as pre-Cambrian quartzite at Wolf Creek, Western
Australia. Even the highly resistant iron meteorites found around this
crater have almost completely weathered away. Only tiny specks and thin
veinlets of metal are now visible on the cut surfaces of meteorites
that, untold hundreds of thousands of years ago, were solid masses of
nickel-iron.

You may have noticed that the widely publicized circular, water-filled
Chubb crater in the Quebec Province of Canada was not included in the
table. This Canadian feature was left out because the answer to each of
the three questions listed earlier in this chapter is no.

    [Illustration:                        COURTESY OF WILLIAM A. CASSIDY
     Two of the deeply weathered meteorites found at Wolf Creek crater
    in western Australia.]

The field parties that have carefully searched the Chubb crater and its
surroundings, even when they used one of the Institute’s powerful drag
magnets, 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 crater. Furthermore, no searcher has discovered any fragments
of ordinary rock showing the effects of the extreme heat and pressure
that accompany large-scale meteoritic impact. Finally, the meteorite
supposed by some to have produced the Chubb crater was not a recorded
witnessed fall, for the crater is of very ancient origin indeed.

Perhaps further search of the Chubb crater site and especially of the
debris in its deep, water-filled interior will succeed in bringing to
light either specimens of meteorites or of silica-glass or other
products of meteoritic impact. If so, then and only then will
identification of the Canadian crater as a meteorite crater be
justified.

Up to this point, we have talked only of very old meteorite craters. But
two crater-producing meteorite falls have occurred within this century,
both in Siberia. The Ussuri fall was one of these and the more recent of
the two.

The earlier and more unusual fall took place on June 30, 1908, at about
8:00 a.m., approximately 40 miles northwest of the trading post of
Vanovara. A fireball exceeding the sun in brilliance flashed across the
sky and was followed by extremely violent airwaves and earth-tremors.

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
impact, as for example, in the village of Vanovara. On both rivers and
lakes in the area of fall, the pressure wave in the air piled up high,
sharp-fronted water waves that resembled the bores on the Seine and
Severn and that upset fishing craft and swamped other small boats.
Throughout a wide region at somewhat greater distances from the impact
point, tidal-like bores were raised on rivers and lakes. So gigantic was
the atmospheric disturbance, that it was detected at almost every
station in the world where sufficiently sensitive barometers were in
operation.

Eyewitnesses of this meteorite fall said that at the time the fireball
passed near them, they felt almost unbearable heat.

A huge “fiery pillar” rose above the point of impact, which by good
fortune was in a desolate and almost uninhabited swampy basin between
the Chunya and the Podkamennaya (i.e., “Stony”) Tunguska rivers. The
meteorite fall takes its name from the latter stream.

The central portion of the region of impact is marked not only by a
number of craters in the swampy terrain, but also by mute evidence of
the extraordinary destructive power of the Podkamennaya Tunguska
meteorite. Over an area of many square miles, the explosion blew down
the standing forest so that the tops of the overthrown trees (estimated
by the Russians to number more than 80,000,000!) all point away from the
impact center. 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 Mexico.

Within the area of fall, countless reindeer belonging to the native
Tunguse herdsmen were killed, only their charred carcasses remaining.
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 camps. In at least one
instance, a Tunguse was so overcome by the terrible event he had
witnessed that he was “sick for a long time.” The whole impact-region
came to be considered as accursed by the natives, who abandoned the use
of all trails crossing it.

For many years the Podkamennaya Tunguska fall was neglected, partly
because of the remoteness of the area in which it occurred, partly
because of unsettled conditions in Russia; but chiefly because, in
general, the Russian scientific and governmental officials simply did
not believe the “fantastic” tales concerning the fall told by the native
Tunguses, from which we have given a few details above.

Belated study established, however, both the truthfulness of the Tunguse
reports and the exceedingly unusual character of the meteorite fall
itself. In spite of the overwhelming and, in fact, worldwide evidence
that the Podkamennaya Tunguska fall was one of the greatest and most
violent in history, no meteorites have ever been recovered from any part
of the region devastated by its impact. It is the one and only true
meteorite crater that is meteoriteless!

This strange circumstance led the senior author to suggest, in 1941,
that the almost incredible Podkamennaya Tunguska incident had resulted
from the infall of a meteorite that, together with an equivalent mass of
the earth-target, was transformed into energy upon contact with our
planet. How can such extraordinary behavior be accounted for?

    [Illustration:                        LEONID A. KULIK PHOTO. SOVFOTO
     Infall of meteorite, June 30, 1908, had this effect on a Siberian
    forest. See p. 55.]

The most obvious explanation involves a new and wider concept of matter.
Ordinary terrestrial matter is regarded as composed of atoms having
positively charged nuclei around which negatively charged electrons
revolve.

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 positive, as in the second
diagram. Matter built up from atoms like those in this diagram would
bear somewhat the same relation to ordinary matter that -2 does to +2.
Such matter is now known variously as _reversed matter_, _anti_-matter,
or, as it was first called by V. Rojansky, _contraterrene_ matter. In
recent years, scientists at the University of California Radiation
Laboratory have produced experimentally all the fundamental particles
necessary for the creation of contraterrene matter.

What would happen now if a contraterrene meteorite penetrated into the
ordinary matter of the earth? The answer is that just as an electron and
a positron mutually annihilate each other when they collide, so the
meteorite and an equal mass of the earth-target itself would vanish at
the instant of impact. The nearest simple analogy to the actual complex
physical situation is represented by the familiar equation -2 + 2 = 0.

Unlike “summing to zero” in simple arithmetic, however, the
disappearance of mass, technically called its annihilation, results in a
release of energy, as was long ago observed in the case of
electron-positron annihilation. Where considerable masses are
annihilated, as in an A-bomb explosion, the amount of energy released is
tremendous, as is now well known to everyone.

    [Illustration: A. Representation of the structure of an atom of
    ordinary terrestrial matter. The nucleus is positively charged and
    around it circle negatively charged electrons.

    B. Representation of the structure of an atom of contraterrene
    matter. This is the reverse of the situation in (A). The nucleus
    here is negatively charged, and around it revolve positively charged
    electrons, also called positrons.]

The effect of such an energy release as would accompany the infall of a
contraterrene meteorite would be a _natural_ nuclear explosion of vast
power. Such an explosion would account for all the sensational phenomena
observed at the time of the Podkamennaya Tunguska incident; and,
furthermore, would explain why the Russian investigators have never
succeeded in recovering meteorites from this fall. (Further details, p.
102.)

If the Podkamennaya Tunguska meteorite was contraterrene, then the soil
in the impact area must have been made radioactive in the same way that
the earth around the “ground zero” of a nuclear explosion is
contaminated by radioactivity. After the senior author had repeatedly
urged Russian scientists (who are the only ones that have been permitted
to visit the site of the Podkamennaya Tunguska fall) to try to detect
any long-lasting radioactivities that might still be present in the
ground at Podkamennaya Tunguska, such a radioactivity survey was finally
carried out in the summer of 1960. According to an official report of
the Soviet news agency TASS, the investigators obtained “abnormally high
radioactivity readings” which the Russians tentatively considered to be
the result of “a natural nuclear explosion” occurring in the
Podkamennaya Tunguska area on June 30, 1908.

Science-fiction fans in the U.S.S.R. would like to believe that this
“nuclear explosion” resulted from the impact of a Martian spaceship
rather than a contraterrene meteorite. Reputable Russian scientists,
however, have shown how completely absurd this “fable” of a Martian
landing really is.

When and where will the next crater-producing fall occur? Perhaps on the
earth, perhaps on the moon, for our nearest neighbor in space has also
been the target of meteorites of huge size. The effects of this
meteoritic bombardment are shown by the rarest and most striking type of
lunar crater: that which exhibits long, bright rays extending outward
from the crater itself as the spokes of a wheel radiate from its hub.
These so-called _ray-craters_ show to best advantage at or near the time
of full moon, when they become one of the most remarkable features
visible on our satellite.

    [Illustration:    G. W. RICHEY PHOTO. COURTESY OF YERKES OBSERVATORY
     The lunar ray-crater Tycho.]

In earlier days, most scientists believed that the craters on the moon
had _all_ been formed by volcanic action. 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 past. Both views are better examples of how scientific
“fashions” control men’s minds than they are of explanations that really
account for all of the observed facts—as any acceptable explanation must
do.

Those who have studied the moon most carefully from an uncomfortable
seat in a cold observatory rather than from a warm, comfortable armchair
are well aware that instead of just one type of lunar crater, there are
really _two_ quite distinct types. No single “explanation” can be
expected to explain satisfactorily lunar features as strikingly
different as:

First, the rare and distinctive _ray-craters_ described above, which are
scattered at random over the moon, just as the points of impact of
meteorites are upon our own globe. (Roughly defined, a random
distribution is one showing no apparent pattern. For example, if you
were to throw a handful of rice up in the air, the points where the
grains of rice finally came to rest on the floor would be randomly
distributed or very nearly so.)

Second, the ordinary or “run-of-the-mill” craters sprinkled in profuse
but non-random fashion over the visible face of our satellite.

The ray-craters on the moon are the counterparts of the meteorite
craters on the earth. This fact is shown not only by their random
distribution, but by the long, bright rays which gave them their name.
On the earth, rays of similar appearance, composed of thrown-out
material, are one of the most characteristic features of explosion
craters, whether the cause of the explosion is the high-speed impact of
a great meteorite or the detonation of a charge of high explosive
(either conventional or nuclear).

The hypothesis that meteorite craters do exist on the moon is therefore
justified even though it applies to far fewer craters than its
supporters believe.

As for the ordinary, non-ray lunar craters, these features are not at
all volcanic craters in the usual sense. One of the few good things to
come out of World War II was the first satisfactory explanation of the
“run-of-the-mill” craters on the moon. Jeremi Wasiutynski, a brilliant
Polish scientist forced to take refuge in Norway, sought to explain
these craters as originating in _convection_ processes.

While the term “convection” may not be familiar, the role convection
plays in filling the sky with beautiful clouds on a hot summer’s day is
well known. Such cloud formation results from convection in the gaseous
free atmosphere. Much more remarkable and regular are the results of
_controlled_ convection in layers of _liquids_ rather than gases.
Laboratory investigation of the effects produced by convection processes
in heated liquids formed the basis for Wasiutynski’s new theory.

According to this theory, 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 size, shape, and
distribution of the common lunar craters. In far more satisfactory
fashion than any other theory so far proposed, the convection-current
hypothesis of Wasiutynski explains the many and distinctive
characteristics of the non-ray craters on the moon.


               RECOGNIZED METEORITE CRATERS OF THE WORLD

  NAME                      LOCATION                             DATE OF
                                                             RECOGNITION

  Canyon Diablo             Coconino County, Arizona                1905
  Odessa                    Ector County, Texas                     1929
  Henbury                   McDonnell Ranges, Central               1932
                            Australia
  Wabar                     Rub’ al Khali, Arabia                   1932
  Campo del Cielo           Gran Chaco, Argentina                   1933
  [2]Haviland (Brenham)     Kiowa County, Kansas                    1933
  Mount Darwin              Tasmania                                1933
  [3]Podkamennaya Tunguska  Yeniseisk District, Siberia             1933
  Box Hole Station          Plenty River, Central                   1937
                            Australia
  Kaalijarv                 Oesel, Estonia                          1937
  Dalgaranga                Western Australia                       1938
  Ussuri (Sikhote-Alin)     Eastern Siberia                         1947
  Wolf Creek                Wyndham, Kimberley,                     1948
                            Western Australia
  Aouelloul                 Adrar, Western Sahara                   1952




                     5. HEAVEN KNOWS WHERE OR WHEN


Meteorites have been falling upon our planet for a long time—how long,
it is hard to say with accuracy. Up to now, no specimens certainly
identified as meteorites have been found in ancient rock layers.
Scientists have been able, however, to estimate the age of several
meteorite craters on the basis of the degree of weathering not only of
the crater rims, but also of the meteorites found around the craters.
Age estimates have also been based on the ages of fossils found in
silted-up crater interiors and on other related indirect evidence.

As we have already noted, the Canyon Diablo, Arizona, crater is thought
to be 20,000 to 70,000 years old. The Odessa, Texas, crater is at least
200,000 years old; and the Haviland (Brenham), Kansas, craters more than
600,000 years old. Clearly, meteorite falls have been occurring over a
very long period of earth history.

For many years, 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 numbers.

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 space. Not only is the earth
in motion, but it is in very complicated motion. Our earth revolves
about a sun which is also in motion through space. At the same time, the
earth is rotating on its axis. A single point on the surface of the
earth therefore traces a very erratic path in space with the passage of
the years, and the likelihood that this particular point would be struck
by more than one meteorite (if indeed by one!) must be very small.

Studies have shown that the people of the earth have a great deal more
to do with “concentrations” of meteorite recoveries than anything else.
_Population density_ is the first important factor. Clearly, the more
people living in a given area, the higher the probability that a
meteorite fall will be seen and reported and that the fallen mass itself
will be recovered. A prime example is India, one of the most densely
populated regions of the world. Of the 102 meteorites recovered in that
country up to 1953, 97 were of witnessed fall. 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 people. Apparently, the
majority of Indian meteorites have been recovered as they fell, for only
5 unwitnessed falls are recorded for that country.

On the other hand, from French West Africa only 5 falls and 3 finds have
been reported throughout an area slightly larger even than India’s. This
country thus provides an example of a sparsely populated region, in many
provinces of which a meteorite fall might pass unobserved, and a fallen
meteorite might remain undiscovered.

A second factor is the _degree of civilization_ reached by the
inhabitants of a particular area. 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 falls. Such a populace will also be more likely to bring
suspected meteorites to the attention of experts.

For example, up to 1953, 55 witnessed falls and 3 unwitnessed falls were
known from France, a country of relatively small area, but with a high
population density and an advanced degree of civilization. From the
whole vast area of Siberia, on the other hand, only 20 meteorite falls
and 23 finds have been reported during the same interval.

In the past, scientists have suggested that various natural forces, such
as the magnetic field of the earth or the attraction of high and massive
mountain ranges, might cause more meteorites to fall in one place than
another. But all available evidence indicates that this is not the case.
The fall of meteorites upon the earth has been and is a process that
shows no apparent pattern. Only “human” factors (like population density
and scientific interest in meteorites) can be considered as accounting
for any concentrations of meteorite falls in particular regions or
countries.

In historic times, the number of man-built structures (houses, barns,
hotels, office buildings, etc.) has increased tremendously. Such
structures have presented an ever-expanding target to hits by falling
meteorites. On pages 73, 74 is a listing of some of the meteorites that
have struck and damaged buildings during the last 150 years or so. The
items included in this list were chosen on the basis of interest,
authenticity, and concreteness of detail.

The stories of all these meteorite falls are exciting, but none more so,
perhaps, than that of the Beddgelert, North Wales, stone. This meteorite
fell in the small hours of the morning on September 21, 1949. Not many
people saw the fireball that accompanied its descent because of the
early hour (1:45 a.m.), but one of the few persons who happened to be
outside said that it resembled a huge rocket as it flashed across the
sky. He also reported that the appearance of the fireball nearly
frightened the swans in the local park to death, the birds fleeing in
all directions.

The manager of one of the hotels in Beddgelert simultaneously was
awakened from a sound sleep by the barking of his dog. This was an
unusual occurrence, and the man was surprised by it. While he was trying
to account for the dog’s peculiar behavior, he suddenly realized that
something quite out of the ordinary was happening outside. He heard a
series of unevenly spaced bangs that he later compared to “a naval
broadside.” But as the noise died away and nothing further happened, he
went back to sleep.

About noon on the next day, the manager’s wife went into the upstairs
lounge of the hotel, a room right under a part of the roof. She was
astonished to find plaster dust all over the floor. It had obviously
come from a jagged hole in the ceiling. And, on the floor, she found an
odd-looking dark stone.

Investigation showed that this stone had indeed fallen through the roof.
It had made a neat round hole in four overlapping thicknesses of slate,
shattered the underlying lath, made a dent in the lower edge of an
H-section iron girder, and had finally broken through the plaster
ceiling into the hotel’s upstairs lounge.

Although it was clear that the stone had come through the roof, the
hotel manager did not connect the event in any way with the peculiar
noises he had heard during the preceding night.

He tried to cut the stone on an emery wheel, but it was too hard.

That evening, an old miner in the hotel restaurant recognized the stone
as a meteorite. Many years before, he had visited a museum and had seen
specimens of meteorites on display there.

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
roof. But, unfortunately, these appear to have been thrown away at the
time the roof was repaired. This fact is mentioned to show that
important scientific evidence is sometimes unwittingly destroyed before
investigators can get a chance to examine it.

Along with the rapid increase in the number of man-made buildings has,
of course, gone a simultaneous increase in the world’s population
itself. A person does not present as large a target to a falling
meteorite as a house or barn, but even so, if there were enough people
on the earth, it would seem that someone was bound to be hit sooner or
later.

    [Illustration:                              G. W. SWINDEL, JR. PHOTO
                           COURTESY OF ALABAMA MUSEUM OF NATURAL HISTORY
     The Sylacauga, Alabama, stone meteorite and the roof (note circle)
    through which it plunged and struck a person.]

Actually, the first _authentic_ case of a person being struck by a
meteorite did not occur until November 30, 1954. Even then, the hit was
an indirect one. At Sylacauga, Alabama, a meteorite fell through the
roof of a house, went through the ceiling of the living room, struck the
top of a radio, and—bouncing in a 6-foot arc—hit the lady of the house,
who was taking a nap on the couch. Fortunately, nearly all of the energy
of the meteorite was spent by the time it struck the woman, and,
moreover, she was covered with two heavy quilts so that she was not
critically injured. But she did receive bruises serious enough to send
her to the hospital.

The instances just given show that a number of meteorites have struck
buildings and, in one case, a cosmic missile has hit a human being.
Nevertheless, such events are really quite rare. In fact, mathematical
calculations indicate that, on the average, we can expect one meteorite
to fall per township (36 square miles) per 1000 years. 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 meteorite!


   SELECTED LIST OF METEORITES THAT HAVE STRUCK AND DAMAGED BUILDINGS

  NAME AND LOCATION               TYPE     APPROXIMATE WEIGHT         YEAR

  Baxter, Missouri                stone    611 gm.[4]                 1916
  Meteorite penetrated roof and struck a log joist, which checked the fall.
  The stone lodged in the attic.
  Beddgelert, North Wales         stone    794 gm.                    1949
  Meteorite made a clean hole through 4 thicknesses of slate roof. It then
  shattered underlying wood, made tiny dent in bottom edge of H-section iron
  girder, and broke through plaster ceiling into hotel lounge below.
  Benld, Illinois                 stone    1770 gm.                   1938
  Meteorite penetrated garage roof, top of car, and seat cushion. It struck
  and put 1-inch dent in muffler, then bounded back up and became entangled
  in seat cushion springs.
  Bethlehem, New York             stone    11 gm.                     1859
  Meteorite struck the side of wagon house, bounded off, hit log upon ground,
  bounded again, and rolled into the grass. (A dog lying in the doorway of
  the wagon house jumped up, ran out and seized the meteorite, but dropped it
  right away, probably because of the warmth and sulfurous odor of the stone.)
  Branau, Bohemia                 iron     19,000 gm.                 1847
  Meteorite penetrated into room where 3 children were sleeping and covered
  them with plaster and debris. They were unharmed.
  Constantia, South Africa        stone    999 gm.                    1906
  Meteorite penetrated 2 thicknesses of corrugated iron roofing and smashed
  ceiling.
  Kasamatsu, Japan                stone    721 gm.                    1938
  Meteorite penetrated roof of house and stopped on floor. It went through
  roof tile, ⅓-inch wooden roof-panel, and layer of clay 1 inch thick between
  them.
  Kilbourn, Wisconsin             stone    772 gm.                    1911
  Meteorite went through 3 thicknesses of shingles, a 1-inch hemlock roof
  board, and a ⅞-inch hemlock floor board. It then glanced in turn against
  the side of a manger and the stone foundation of the barn and finally
  penetrated 2½ inches into the clay floor of the barn.
  Pantar, Philippine Is.          stone    shower                     1938
  Sixteen stones were recovered; thousands “as big as corn and rice grains”
  fell on roofs.
  Sylacauga, Alabama              stone    3863 gm.                   1954
  Meteorite penetrated composition roof material, ¾-inch wooden decking,
  ¾-inch wooden ceiling, and interior wallboard. It then hit a radio,
  punching a 1-inch hole in plywood top, and bounced 90° towards the east,
  striking woman lying on couch.




                    6. FINDERS FOOLISH, FINDERS WISE


People find a great many meteorites that were not seen to fall. 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 globe. Generally, such meteorites are discovered entirely by
accident, although in recent years quite a few recoveries of unwitnessed
falls have been made by design. This has been the case during the
systematic surveys with meteorite detectors conducted around such
recognized meteorite crater areas as Canyon Diablo, Arizona; Odessa,
Texas; and Wolf Creek, Australia.

The different modes of discovery of meteorites not seen to fall are
interesting in themselves. The largest percentage of finds has
unquestionably been made by farmers. The Plymouth, Indiana, meteorite,
for example, was plowed up or, as the farmer nursing the rib bruised by
his bucking plow would probably prefer to say, “plowed into.” So were
such meteorites as the Algoma, Wisconsin; the Bridgewater, North
Carolina; the Carlton, Texas; and the Chesterfield, South Carolina, to
name only a few. A farmer found the Kenton, Kentucky, iron while he was
cleaning out a spring. Another farmer was removing debris from an
abandoned water well in an attempt to revive it when he discovered the
Richland, Texas, iron. A field drainage project brought the Seeläsgen,
Poland, iron to light. A man planting an apple tree near his house dug
out the Mount Joy, Pennsylvania, iron, and a farmer hoeing tobacco
turned up the Scottsville, Kentucky, iron.

The second largest percentage of finds probably has been made by miners.
Prospectors and placer miners have mistaken numerous iron meteorites for
lumps of silver ore. Among these are the Murfreesboro, Tennessee; Lick
Creek, North Carolina; and Illinois Gulch, Montana, irons. The Aggie
Creek, Alaska, iron was raised by a gold dredge. The gold miners
recognized this meteorite as an unusual “haul” when it announced its
presence by clanging loudly on the metallic screen of the dredge.

Men at work on road construction are also to be thanked for chancing
upon meteorites of unwitnessed fall, for example, the irons found by
road crews at Bear Lodge, Wyoming, and at Bald Eagle, Pennsylvania.

Some meteorites have been “found twice.” At Opava, Czechoslovakia,
archeologists discovered seven pieces of meteoritic iron in a buried
Stone Age campsite—the oldest meteorite collection so far on record!
Apparently the paleolithic inhabitants of the Opava region had gathered
the heavy masses together and used them to bolster the fireplaces in
their rude encampment.

Investigators discovered the Mesaverde, Colorado, iron in the Sun Shrine
on the north side of the Pipe Shrine House, and the Casas Grandes,
Mexico, iron in the middle of a large room of the Montezuma temple
ruins, carefully wrapped in linen cloth like a mummy. Members of an
early archeological survey found the small Anderson Township, Ohio,
meteoritic specimens on altars in mounds of the Little Miami Valley
group of prehistoric earthworks. Some scientists believe that the
American Indians transported these specimens to Ohio from the site of
the Brenham meteorites in Kiowa County, Kansas.

    [Illustration: The Lake Murray, Oklahoma, iron meteorite in place,
    just as it was found. See p. 80.]

Other modes of discovery fall into no pattern and must be regarded as
merely curious. A farmer plowing his field near Pittsburgh,
Pennsylvania, came across a snake. In looking for a suitable stone with
which to kill it, he first seized upon a mass of iron too heavy to lift.
After he had killed the snake with a handy rock, the farmer’s attention
was drawn back to the small but remarkably heavy mass he had first tried
to pick up. He carted it off to the city, where eventually it was
recognized as a meteorite.

In another unusual recovery, fishermen brought the Lake Okeechobee,
Florida, stone up from the waters of the lake in a net—the only such
recovery recorded in the whole literature of meteoritics, although
three-fourths of all meteorites must necessarily fall into water on our
ocean-covered globe. Again, the members of the Australasian Antarctic
Expedition of 1911-1914 were surprised to find the Adelie Land,
Antarctica, stone lying on the snow some 20 miles west of Cape Denison.

Because the true nature of meteorite finds has often been
unrecognized—sometimes for many years—these masses have been put to some
rather lowly uses. The finder of the Rafrüti, Switzerland, iron
meteorite used it as a footwarmer, and many of the heavy irons have been
employed as haystack, fence, and barrel-cover weights, or as anvils,
nutcrackers, and doorstops.

    [Illustration: It’s a whopper! See p. 80.]

Some have fared better, as did the 1,375-pound La Caille, France,
meteorite, which the people of the village used for two centuries as a
seat in front of their church. Others, however, have fared even worse.
Blacksmiths and assayers have smelted up and destroyed a number of iron
meteorites either in the making of tools (like plowshares, axe-heads,
and knife-blades) or in the quest for precious metals. Nearly all of the
iron meteorite that was found by the farmer near Pittsburgh was worked
up by a blacksmith and lost to science. Even the stone meteorites have
occasionally fallen victims to man’s greed for gold. Miners who believed
that the 80-pound San Emigdio, California, stony meteorite was
gold-bearing mashed it to powder in an ore-crusher.

On the contrary, people who, in one way or another, have become
acquainted with the characteristics of meteorites have brought a number
of these objects to the attention of scientists. For example, one of the
University of Nebraska men who worked on the excavation and removal of
the large Furnas County stone meteorite (see Chapter 2) became keenly
interested at that time in meteorites in general, and took the trouble
to learn as much as he could about them. Several years later, after he
had become director of a state park museum in southern Oklahoma, a large
metallic mass was reported to him. The finder of this mass of metal had
known of its existence for some 20 years, but had never succeeded in
getting anyone to examine it carefully. The former field worker took one
look at the object and, on the basis of his knowledge of meteorites,
concluded that it probably was a huge iron meteorite. 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 site. In this way, the Lake Murray, Oklahoma, meteorite was
identified and recovered.

    [Illustration: The Lake Murray core mounted on the meteorite saw
    which cut it in half. One of the worn soft iron saw-blades is held
    above the meteorite by the saw guides. See pp. 167, 168.]

The unoxidized central core of this iron weighed more than 600 pounds.
Before excavation this core was surrounded by a “shell” of oxidized
meteoritic material several inches thick, as shown on page 77. Such a
shell of oxide clearly indicated that the meteorite had been subjected
to weathering in the ground for many thousands of years.

In general, 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 recovery. Most of them
have been presented to men of science for study and eventual display in
some museum collection. Even when kept by their finders, the specimens
usually have been well cared for. After the fall of the Flows, North
Carolina, meteorite in 1849, 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 post. On
the post he put up the notice:

  “_Gentlemen, sirs—please not to break this rock, which fell from the
  skies and weighs 19.5 pounds._”

This landowner obviously realized that nearly everyone has the
unfortunate urge to hammer on strange rocks.

Of course, there have been exceptions to the respectful treatment of
meteorites seen to fall. The finder of one fragment of the Zhovtnevy
Hutor, Russia, fall tossed it into the stove, and a farm woman lost
another by throwing it at an unruly horse. A peasant who thought
meteorites possessed miraculous powers powdered up a piece of the
diamond-bearing Novo-Urei, Russia, stone and ate it!

    [Illustration: A polished and etched face of the Lake Murray
    meteorite. The length of the cut is a good 23 inches.]




                   7. LANDMARKS, SKYMARKS & DETECTORS


The chemist can easily obtain materials for his research work from
reliable supply houses. The meteoriticist (as a scientist who studies
meteors and meteorites is known), is not this lucky. He must search for
the specimens he wishes to investigate wherever they may have landed on
the wide, wide earth. This “needle-in-a-haystack” problem could rarely
be solved if it were not for certain mathematical and instrumental aids
that swing the balance in favor of the meteorite hunter. When meteorites
are seen to fall, these aids can be brought into play only if certain
information is supplied by eyewitnesses of the falls. For this reason,
everyone ought to be acquainted with the facts about meteorite falls
that scientists will need to know in order to make finds, and should
understand how these facts must be reported in order to be of maximum
use to field parties.[5]

The problem of working out the path a fireball has followed in the sky
boils down to this. The investigating scientists must be able to fix the
position _in space_ of certain important points on the fireball’s path.
This idea of fixing points is not really difficult at all. Suppose, to
take an analogy from baseball, we have base runners on first and third.
These two players are intently watching their team’s clean-up hitter,
who is “crowding the plate.” Consequently their lines of sight intersect
at home plate and give a very good “fix on” its position, as navigators
say. This is the way a fix can be obtained in _two_ dimensions; that is,
essentially, in the plane of the earth’s surface.

    [Illustration: A. A fix determined in two dimensions. The lines of
    sight of the runners on first and third intersect at x.

    B. A fix determined in three dimensions. The lines of sight of the
    runners on the first and third intersect at x.]

Now, let us move into the _third_ dimension, since a fireball’s path
through the atmosphere lies in space, not in the “flat” plane of the
earth’s surface. Returning to our baseball diamond, 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 crowd.
While the umpire is dusting off home plate, the two runners on first and
third simultaneously sneak a look to see what the helicopter is doing.
Their lines of sight now intersect at the helicopter and fix its
position _in space_.

Similarly, the location of a fireball path in space is determined by the
fixing of certain points on the luminous streak seen in the sky. Instead
of using only two intersecting lines of sight (those of the runners on
first and third in our analogy), 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 streaked. The more
commonly determined points are those of the fireball’s appearance and
disappearance and those where “explosions” took place. These points are
generally located by use of the method we have described in some detail
above, the so-called _intersecting-lines-of-sight_ method.

The most important point on a fireball path is the point of
disappearance. The most valuable single piece of information you can
supply about a meteorite fall is as accurate an answer as possible to
the question: In what compass direction were you looking when you _last_
saw the fireball? This question has often been twisted around in
newspaper and radio accounts into the meaningless question: In what
direction was the fireball going when you saw it?

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 sky. One person can report only an
_apparent_ direction of motion, which is of little or no value in
locating the last point on the luminous path, generally referred to as
the “end-point.” Therefore, though you cannot by yourself determine the
actual direction in which a fireball is _moving_, you can report the
direction in which you were _looking_ when you last saw the fireball,
that is, due south, southwest, northeast, etc.

    [Illustration: O is an observer squinting along the top of a
    ping-pong table. A ping-pong ball rolls along the top of the table
    from B (beginning) to E (end). To the observer at O, however, 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 OE. By means of a similar
    space-figure, it can be shown that a single observer at O cannot
    determine the _true_ direction of motion of a luminous object in the
    sky, like a meteor.]

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 possible. They then can plot the individual lines of
sight on a good map, marking exactly where these lines intersect. In
this way, 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 path, as this end-point was seen in
the sky by each pair of eyewitnesses.

Instead of using the ordinary compass direction to a fireball’s point of
disappearance, you may prefer, as do astronomers, to use the azimuth.
What we have been calling a “compass direction” is one that is expressed
in terms of the cardinal points: north, south, east, west. An azimuth is
a direction stated in _degrees_. Rough azimuths can be taken with a
compass, but for accurate work, a graduated circle, like that on a
transit or theodolite, must be used. Astronomical azimuths begin at the
_south_ point and continue clockwise full circle to 360°. For example,
the lines of sight in the diagram, p. 87, could very well have been
given as astronomical azimuths. And, in the diagram, p. 91, the line of
sight C₁ could have had the precise designation 118° and C₂ that of
222°.

Every fix serves to guide field parties to areas that are to be
carefully searched for fallen meteorites. 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 ground.

You will notice that so far we have been treating our problem as a
two-dimensional one. We have been working with _directions_ only and
have plotted out direction indicators on a map representing the plane of
the earth’s surface. Now, as we did in our baseball analogy, let us move
into the third dimension.

    [Illustration: Diagram (not drawn to scale) showing plotted compass
    directions to the last visible point on a fireball path. (The point
    denoted by L in next diagram.) Black dots represent positions of
    various observers. Each arrowed line is directed toward the last
    visible point as it was estimated by the individual observer. The
    oval area, which includes points of intersection of all observed
    lines of sight taken in pairs, marks out region in which meteorites
    have probably fallen.]

If, in addition to compass directions to the observed endpoint,
scientists can also obtain the apparent _elevation_, in degrees, of this
point as seen by the various eyewitnesses, then with the help of a
little trigonometry, they can fix the position _in space_ of the
end-point itself rather than the position of its _projection_ on the
surface of the earth.

This same procedure can be followed in fixing the space-position of any
well-observed point on the fireball path. It therefore becomes possible
when _both_ elevations and compass directions are reported for several
points on the fireball path to determine the flight-path or, as it is
technically called, the _trajectory_, of the falling meteorite through
the atmosphere. Trajectory determinations are of great scientific value.

You can estimate the compass directions and elevations to the important
points on a meteorite trajectory at the actual time of fall. 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 fireball.

The accuracy of your measurements can be improved if you have been able
to “line up” the point, L, at which you saw the fireball disappear, with
some familiar object on the horizon, such as a church steeple, a tall
tree, a telephone pole, or a lightning rod on a farm building. 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 fireball. She was able to do this
because she remembered just where it went out of sight behind a familiar
landmark.

    [Illustration: Method for locating a point on a fireball path. (In
    this case the point of disappearance, L.)


  O₁ First observer.
  A₁ Apparent height of point of disappearance (50°).
  C₁ Compass direction of point of disappearance (N 62° W).
  O₂ Second observer.
  A₂ Apparent height of point of disappearance (45°).
  C₂ Compass direction of point of disappearance (N 42° E).]


If the fall occurs at night, you can help investigators greatly if you
are familiar enough with the brighter stars to use them as “skymarks.”
You simply note as quickly and sharply as you can just where the
fireball path was in reference to those prominent stars. 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 fireball;
and, moreover, there is no telling what else your quick eye might have
captured for science.

While looking through a window, Kayser, the Polish astronomer, saw a
fireball appear at Rigel and move to Sirius, where it disappeared. This
observation of his proved to be one of the most accurate and
_significant_ ever made of the fall of a meteorite. For it enabled the
German mathematician, Galle, to show that the Pultusk meteorite, which
produced the fireball Kayser saw, came into the Solar System from
interstellar space!

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 there.

The map and side view of the Norton County, Kansas, meteorite trajectory
show the practical results that the Institute obtained by use of the
intersecting-lines-of-sight method. The fireball accompanying the Norton
meteorite fall appeared at A. The first “explosion” took place at E₁,
the second at E₂, and the fireball disappeared at L.

If markers were dropped straight down to earth from each point along the
trajectory or flight-path of a meteorite through the atmosphere, the
line joining the points where the markers fell would be the
_earth-trace_ of this trajectory. 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 fall. The solid-line arrows
represent the direction of the point of disappearance; the dotted-line
arrows, the point of appearance; the dash-dot arrows, E₁; and the dashed
arrows, E₂. The probable area of fall is shown as an oval-shaped area,
the longer axis of which is identical with the direction of motion of
the meteorite.

    [Illustration: Path of the Norton meteorite.]

The many fragments of all sizes recovered from the Norton fall were all
found within the bounds of this oval-shaped area, although unavoidable
errors of observation placed the center of the oval about 4 miles too
far to the north.

In addition to the questions about direction and elevation, there are a
few more that investigators of meteorite falls would like to have
observers answer.

  At what time (determined as accurately as possible) did the fall
  occur? Knowledge of this time is necessary if the path in which the
  meteorite was moving about the sun is to be calculated by scientists.

  Did you hear any sounds, either while you were watching the fireball
  or after it disappeared? 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 earth, then you were very close to
  where the meteorite came down!

  How many minutes and seconds (again determined as accurately as you
  can) passed between the time when you saw the fireball vanish and the
  instant when you first heard sounds from it? Such sound data permit
  rough determination of the distance from the observer to the point
  where the meteorite fell.

  How long did the sounds set up by the meteorite last, and in what
  direction did these sounds seem to die out?

If you or your neighbors find fragments that you suspect are pieces of
the meteorite, these specimens should be shown to the investigating
field parties at once—preferably undisturbed and in the very places
where they fell. In any event, the suspect masses should not be hammered
on and broken up! Even as late as 1958 in a country as science-conscious
as Germany, a beautiful stony meteorite, seen to fall and speedily found
by an alert group of children playing out of doors, was deliberately
broken up into 5 pieces in order that each of the children (aged 9 years
and up) might take home a “souvenir” of the event. Later, these pieces
had to be laboriously reassembled by scientists before any idea could be
gained of the original shape and surface features of the meteorite.

Even when thorough searches are made, not all the meteorite fragments in
the area of fall may be found for many months. But if the people living
in the region have been alerted and are on the lookout for unusual
specimens or signs of meteoritic impact (such as freshly made holes or
“craters” in the ground, shattered tree limbs, and so forth), the
chances of ultimately finding many or most of the fallen masses are
good.

As we have already mentioned, numerous fragments of the Norton meteorite
(including one weighing 130 pounds) were found within two to three
months after its fall on February 18, 1948. But the main mass was not
discovered until the following August, when a caterpillar tractor nearly
tipped over into the large impact funnel that this huge stone had made
in the earth. Fortunately, field searchers from the Institute had
already talked to one of the farmers using the tractor and had told him
that just such a “crater” might be found in the very area under
cultivation. Consequently, the crater was promptly reported.

In surveys concerned with the location and recovery of meteorites _not_
seen to fall, we find that sometimes meteorite fragments, particularly
the smaller ones, lie on the surface of the ground or at shallow depth.
Such fragments were probably too light to penetrate deep into the ground
or, in the years since their fall, the action of rain, wind, and frost
has uncovered them.

In such cases, 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 aids. Visual searches
of this type have been very successful, for example, around the Canyon
Diablo crater, where almost the entire plain out to several miles from
the rim once was sprinkled with large and small fragments of meteoritic
nickel-iron. This type of meteorite hunt is of only limited
effectiveness because the specimens (or at least a part of each one)
must be visible to the searchers.

    [Illustration: Collecting small surface specimens of meteorites with
    portable detecting devices: a powerful alnico magnet mounted on a
    light wooden sled, and a horseshoe magnet at the end of a cane. See
    p. 98.]

To increase recoveries, searchers have employed, in addition to their
eyes, various types of permanent magnets, either mounted on the end of a
cane and used to probe the upper few inches of loose soil, or dragged
behind the searcher on a small, light sled. Meteorite hunters have also
used more powerful portable electromagnets to collect large amounts of
meteoritic material (both solid iron and iron-shale) not only from the
surface but also from shallow depths. Even the best of these simple
magnetic devices, however, are useless in the detection of really deeply
buried meteoritic material.

Meteorites do not merely fall upon the earth (as most astronomical
textbooks still insist), but usually penetrate into it—often quite
deeply. In fact, one of our mathematical investigations showed that
perhaps 100,000 times as much meteoritic nickel-iron is concentrated
below maximum plow-depth (approximately one foot) as lies above that
depth. Clearly, 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 science. This need was answered by the development
of special _meteorite detectors_.

Although meteorite detectors working on several different principles
have been constructed, we shall limit attention here to the simplest and
most field-worthy design. The essential principle on which it operates
is one familiar to any Boy or Girl Scout who has used a magnetic
compass. 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 size, such as an automobile. 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 depends. It is this
very characteristic, so bothersome to the user of a compass, that is the
principle on which meteorite detectors work. For if an electrically
driven meteorite detector capable of generating its own magnetic field
is carried over a deeply buried iron meteorite, the instrument’s
magnetic field will be distorted by the presence of the metal mass, just
as the local magnetic field of the earth was distorted by the metal of
the automobile.

    [Illustration: A 146-pound iron, found by this girl without the use
    of instruments although only a small corner of the meteorite was
    visible above the surface of the ground.]

    [Illustration: A commercially built meteorite detector in
    operation.]

The operator of such a meteorite detector wears earphones and watches a
signal needle in plain sight on the top panel of the detector. Since the
phone and signal-needle circuits of the meteorite detector are _in
balance_ only when the magnetic field generated by the detector is
undistorted, 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 needle. If, as in all buried treasure
stories, we use “X” to stand for the spot where the signals from the
detector are strongest, then the meteorite-hunter has only to dig deep
enough at “X” to recover the celestial treasure-trove he is after.




                        8. THE NATURE OF METEORS


In answer to an exam question, a freshman astronomy student wrote:

  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 right!

Doggerel or not, the student’s definition correctly stated the true
distinction between the two terms, and the teacher marked his off-beat
answer correct.

Defined in more scientific terms, a meteor is the streak of light
(usually of brief duration) that accompanies the flight of a particle of
matter from outer space through our atmosphere. This particle may be as
small as a tiny dust grain or as large as one of the minor planets which
are called asteroids. Fortunately for the inhabitants of the earth, most
of the meteor-forming masses encountered by our globe are of the
“small-fry” variety!

As the rapidly moving particle plunges earthward through denser and
denser layers of atmosphere, the air molecules offer ever-increasing
resistance to its passage. This resistance heats up the meteorite body
until it glows. Technically speaking, it becomes incandescent. _The
meteor is this incandescence._ We see it as a darting point. Or as a
ball of white, orange, bluish, or reddish light. But the _material
object_ that produced this light is the _meteorite_. The distinction
between these two terms—meteor and meteorite—we must emphasize again and
again because people continue to use them incorrectly, as, for instance,
when they keep saying “meteor crater” instead of “meteorite crater.”

The majority of the meteors we observe represent the heat-induced
“evaporation” of exceedingly small fragments of cosmic matter. 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 melt.

These residues descend slowly through the atmosphere and may be carried
for great distances. Afterwards, 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 meteorite. This is a
fact that, for example, one school of modern Russian meteoriticists
overlooked when they were dealing with tiny granules of meteoritic dust
that had been recently found at Podkamennaya Tunguska. These scientists
tried to identify the tiny granules with the meteorite that had fallen
there, June 30, 1908. But the members of the latest (1958) Russian
expedition to that region about the impact point of 1908 clearly
recognize the widespread character of meteoritic dust. 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
ago.

If sizable chunks of meteoritic material enter the atmosphere, they may
produce exceptionally large and brilliant meteors. A spectacular meteor
is generally known as a “fireball” if it is as bright as Venus or
Jupiter. It receives the French term _bolide_ if, in addition to showing
great brilliance, its flight is accompanied by detonations like the
alarming sounds heard at the time of the Ussuri and Norton meteorite
falls.

    [Illustration:            COURTESY OF UNIVERSITY OF NEW MEXICO PRESS
     A bright Giacobinid meteor, photographed from a B-29 during the
    shower of October 9, 1946. See p. 115.]

The term “shooting star,” which is often applied to meteors, in
newspapers and magazine articles, is a misnomer. A meteor is _not_ a
distant sun (that is, a star) in rapid motion, for the whole path of the
meteor lies close at hand within a restricted zone of the earth’s
atmosphere.

The word “meteor” comes from the Greek word _meteōra_, which once
applied to any natural occurrence _in the atmosphere_—for example,
rainbows, halos, auroras, and so forth. Nowadays, the word “meteor” is
used in a much more specialized sense than it was by the ancient Greeks.
We have a specialized word, _meteoritics_, for the study of meteors and
meteorites. No one should confuse meteoritics with _meteorology_, which
is the science of things _other_ than meteors and meteorites, in the
atmosphere—for example, clouds, storms, air currents.

The region in which meteoric phenomena take place was long the subject
of controversy. Some persons felt that meteors were nearby, like
lightning. Others said that they moved at the distances of the remote
fixed stars. This controversy on the whereabouts of meteors became
heated, although it could have been settled quickly by a simple
experiment you can try out for yourself.

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 closed. Repeat this
experiment with the pencil held at arm’s length. In the first case, the
pencil will seem to shift position very greatly; in the second, although
the same base line (the distance between your eyes) is used, the pencil
will seem to shift position only slightly.

Such an apparent shift in position is called a _parallactic
displacement_, or, simply, _parallax_. The notion of parallax is of the
greatest importance in most branches of astronomy, and it leads (with
proper instruments and a little mathematics) to exact determinations of
the distances of remote objects.

For our purpose, we need not go into all the interesting but complicated
details. Our experiment with the pencil shows that if a meteor was close
by, like a blinding bolt of lightning, then, as seen by a pair of
observers separated by only a few blocks, the meteor would show a large
parallax. But if this meteor was as far away as the stars, it would show
no parallax at all, no matter how widely the pair of observers were
separated on the earth.

There were many clever scientists among the Greeks, 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
atmosphere. The earliest calculations of meteor heights that are so far
known, however, were made in Bologna, Italy, in 1719 and 1745—long after
the heyday of Greek science.

The meteor heights found by the Italians were quite low in the
atmosphere, probably for two reasons. First, the visual (unaided-eye)
observations they had to use were made by eyewitnesses stationed so
close together that accurate fixes were impossible. Secondly, these
visual observations must have related only to the very brightest and
therefore lowest portions of the luminous paths of the meteors through
the atmosphere.

In 1798, two German students operating from carefully chosen and widely
separated stations began the systematic observation of meteors for
parallax. They found that the height of appearance of most meteors lay
between 48 and 60 miles above the earth’s surface. It is now known that
most meteors, as observed with the naked eye, appear at about 70 miles
and disappear at about 50 miles above the surface of the earth. These
figures, obtained from visual work, still stand in spite of the
development of such modern techniques as photographic and radar
recording of meteor paths.

Rarely, meteors may appear at heights of 150 or more miles and fireballs
may penetrate to within a few miles of the earth. The average meteors,
however, appear and disappear within a well-defined, high-altitude zone
in the atmosphere. Fortunately, this atmospheric zone serves us as an
effective shield against the constant bombardment of the smaller and
much more numerous particles from outer space.

In earlier times, scientists thought that the particles becoming visible
as meteors must be tiny dense masses of iron or stone like the material
composing the recovered meteorites. Most modern investigators, however,
believe that the typical meteor-forming particles may be small loosely
bound-together “dust-balls”; that is, fluffy clusters of matter held
together by frozen cosmic vapors, generally referred to simply as
“ices.” In any event, these masses are usually very small, ranging
perhaps from the size of a pinhead to that of a marble.

Because we cannot collect the tiny masses that are seen only as meteors,
it is impossible to determine their composition by ordinary laboratory
methods. 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 atmosphere.

We can examine this meteor light by using the spectroscope and
spectrograph. Through these specially designed instruments we can make
the meteor light reveal the chemical elements present in the
incandescent masses. Each such element sends out light rays as
characteristic of its nature as fingerprints are of the individual who
made them. Photographs taken of these characteristic light rays are
called _spectrograms_, and what might be termed the “fingerprints of
light” recorded on these spectrograms are known as _spectra_—which is
the plural of the word _spectrum_. If the source of light is a meteor,
the photograph shows a meteor spectrum.

From a study of a considerable number of good quality meteor spectra,
scientists have found that the principal elements in the masses
responsible for meteors are iron, calcium, manganese, magnesium,
chromium, silicon, nickel, aluminum, and sodium.

As we have already noted, the resistance encountered by meteor-forming
particles as they dash through our atmosphere is so great that they
become incandescent and vaporize. These small bodies must therefore be
in very rapid motion.

Before we attempt to find out the nature of the paths in space followed
by meteorites, we must take into account the fact that these bodies are
observed from a station—the earth—which is itself in rapid motion. You
may have noticed that on a still day, when rain drops fall vertically
downward, the streaks they leave on the windows of a swiftly moving car
are not vertical but almost horizontal. Obviously, 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 down, and it is only the
forward motion of the car that makes them leave horizontal streaks.

    [Illustration: Diagram showing meteorite moving along a “closed”
    (elliptic) orbit, e, which intersects the earth’s orbit, E. Held by
    the gravitational attraction of the sun, the meteorite is a
    permanent member of the Solar System.]

Similarly, neither the apparent speed nor the apparent direction of
motion of a meteorite with respect to the moving earth is significant.
The important factor is the meteorite’s velocity _with respect to the
sun_ at the time the meteorite is picked up by the earth.

    [Illustration: Diagram showing meteorite moving across the earth’s
    orbit, E, along an “open” (hyperbolic) orbit, h. 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 planet. The sun, however, in any
    case is able to change materially the direction of motion of the
    transient visitor to our Solar System.]

This factor enables us to determine in which of two possible kinds of
path the meteorite was moving _before_ it was “fielded,” as we might say
in baseball, by the earth. This factor tells us whether the meteorite
was moving about the sun in a relatively short, closed, oval-shaped path
or, instead, was following an indefinitely long, open path which began
in the depths of space and would have returned there if the collision
with the earth had not prevented.

Either type of path is technically called an _orbit_. The closed orbits
are what the mathematicians term _ellipses_; the open orbits,
_hyperbolas_.

To scientists, the nature of the orbits followed by meteorites is most
important, especially in efforts to determine the mode and place of
origin of these bodies. To rocket engineers and astronauts, 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 orbits.

The greater the speed of these cosmic “hot-rods,” the more dangerous
they are to space travelers. For example, a mere grain of nickel-iron
moving at 40 miles per second is quite as lethal as a .50-caliber
machine-gun slug, which, relatively speaking, is traveling at only a
snail’s pace.

As our earth moves along its orbit about the sun, meteoritic bodies can
run into it from any direction. The direction from which they do
approach strongly influences the speed of these bodies as they plunge
through the earth’s atmosphere. 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 second. For example, the speed calculated from Harvard
meteor-photographs of one such not-too-spectacular “rear-end” collision
amounted to no more than 7.3 miles per second, just about the speed a
rocket must acquire to escape from the apron strings of Mother Earth.

    [Illustration: Meteor shower. Earth and particle-swarm passing
    through the intersection of their orbits at nearly the same moment.]

In contrast to such a “rear-end” collision, the speed observed would be
far greater if the meteorite happened to collide exactly “head-on” with
the earth. For, in this case, the orbital speed of our planet would be
_added_ to that of the meteorite about the sun. As an example, suppose
that at the earth’s average distance from the center of our Solar
System, the speed of a meteorite with respect to the sun were 32.23
miles per second. (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 Ridge, Massachusetts.) Then if
such a meteorite ran “head-on” into the earth, the speed observed for it
in the atmosphere would be over 51 miles per second. And mathematics
would show that the orbit of this meteorite with respect to the sun was
a wide open hyperbola.

If the orbit of the earth and the orbit of a swarm of particles of
cosmic matter intersect, and if the earth and the swarm pass through
this intersection in space at nearly the same moment, multitudes of
meteors appear. We then say that a _meteor shower_ takes place. The
position of the point at which the particle-swarm crosses the earth’s
orbit about the sun fixes the date of the meteor shower.

Because the particles that make a meteor shower are moving through space
along parallel paths as they come into the earth’s atmosphere, the
meteors all seem to shoot out from a single small area in the sky. You
may have seen something like this in the case of the sunrise or sunset
effect known as “the sun drawing water.” In this more familiar
phenomenon, the sun’s disk is the area from which shafts of sunlight
radiate out in a beautiful, if somewhat irregular, fan-like pattern. The
area from which the meteors of a given shower seem to come is the
_radiant_ of that shower.

Meteor showers are named for the constellation in which their radiant
lies. The suffix “-id” (Greek for “daughters of”), or some modification
of this suffix, is added to the name of the constellation from which the
meteors seem to radiate. The Orionid radiant, for example, is in Orion,
the Hunter; the Leonid radiant is in Leo, the Lion; and the Lyrid
radiant is in Lyra, the Harp. Exceptions to this rule do occur, however.
Astronomers may refer to a shower sometimes appearing on the night of
October 9 as the “Giacobinid” shower in honor of the comet
Giacobini-Zinner, which is associated with this particle-swarm.

    [Illustration: Radiant of a meteor shower. Generally not a point but
    a small area, here intentionally exaggerated in size. Solid arrows
    represent plotted paths of observed meteors. By extending these
    paths backwards, observer can determine the radiant.]

In the course of each year, the earth passes through a number of
particle-swarms of varying densities. Some of the resulting meteor
showers, like the Leonids and Giacobinids, are very feeble in most
years, but sometimes produce spectacular displays.

The more important recognized meteor showers are:

  NAME OF SHOWER                       DATE OF MAXIMUM
  Quadrantids                          January 1-3
  Lyrids                               April 21
  Eta-Aquarids                         May 4-6
  Perseids                             August 10-14
  Giacobinids (Nu-Draconids)           October 9
  Orionids                             October 20-23
  Leonids                              November 16-17
  Geminids                             December 12-13

Certain daytime streams are also known to be active during June and
July. These daytime showers are, of course, invisible in the glare of
sunlight, but they can be picked up by radar devices like those used in
World War II to spot enemy airplanes.

Some meteor showers have been splendid enough to make a place for
themselves in the historical record. Examples are the Leonid returns of
1833 and 1866, and the Giacobinid showers of 1933 and 1946. During these
displays, meteors fell in a veritable fiery snowstorm, several hundred
meteors sometimes appearing within a minute.

Not every annual return of a meteor shower is spectacular, however,
since conditions may not be favorable each year for a brilliant display.
After all, both parties to a traffic collision at an intersection must
try to pass through the intersection at the same time. Our earth, like a
well-managed train, always goes through the intersection on schedule,
but the particles responsible for meteor showers are much more erratic.
They may be early or late—or they may not show up at all. Of the meteor
showers seen annually, the Perseids are the most dependable. The Leonids
put on their best shows at intervals of 33 years (1799-1800, 1832-33,
1866, etc.). The Giacobinids at intervals of 6½ years (1933, strong;
1939-40, poor; 1946, magnificent).

If you plan to observe a meteor shower, here are some suggestions. You
will need:

  Acquaintance with the stars, both faint and bright, in the region
  containing the radiant of the shower.

  Comfortable reclining lawn-chair.

  Warm clothing (including blankets) for winter showers or summer ones
  at high elevations.

  A patient family that will not only approve of your observing but will
  help you get up to watch after midnight, when most showers are at
  their best.

  A corner of your back yard (or sun roof) where you can shade your eyes
  from street lights and other illumination.

  Timepiece, preferably with radiant dial.

Sit back and watch Nature put on her show. Any records you make may have
some scientific value even if you note only these two things: Hourly
number of meteors seen. Condition of the sky (clear, hazy, cloudy, etc.)
during each hour of your watch.[6] At present, we know of only one
instance in which it seems probable that a meteorite came to earth
during a meteor shower. The Mazapil, Mexico, iron meteorite fell at 9:00
p.m. on November 27, 1885, during a return of the now very weak Bielid
meteor shower. Scientists still cannot decide whether or not a mere
coincidence was involved in this case.

As we have already mentioned, 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 melt. Some cosmic
particles, the _micro-meteorites_, are so tiny that they “stall” rather
than fall down. These minute objects do not melt or disintegrate and so
preserve their original cosmic form unchanged. 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 made.

One of the simplest methods of collecting this so-called “meteoritic
dust” is to expose a sticky glycerine-coated glass microscope slide for
at least a 24-hour period in a protected spot well away from locations
where any industrial contamination is in the air. At the end of the
period of exposure, the “catch” on the slide is examined
microscopically, and the individual trapped particles are counted and
classified. Meteoritic dust is also carried down to the ground by rain,
snow, and hail and can therefore be obtained by filtering rainwater or
melted glacier-ice, snow, and hail.

Such collection efforts have been plagued by the difficulty of
identifying the particles. How can a collector be sure that the dust he
has trapped, even though magnetic and possibly even in part metallic,
does not come from some smelter or other industrial plant? Because of
such uncertainties, the current estimates of the annual deposit of
meteoritic dust for the world range from approximately 20 tons to
several million tons. We need improved collection and identification
techniques if we are to obtain trustworthy figures.

Recent analyses of rainfall records indicate that the infall of
meteoritic dust produces at least one interesting weather-effect. These
analyses show that rainfall peaks often occur some 30 days after the
appearance of important meteor showers. Apparently, as meteoritic dust
particles from the meteor showers filter down through the cloud systems
in the lower layers of the atmosphere, the individual particles serve as
centers about which atmospheric moisture condenses to form raindrops.
The time lag of approximately a month is considered to be due to the
very slow rate of fall of such tiny particles. It looks very much as if
Mother Nature had beaten man to the idea of “seeding” the clouds to
produce rainfall!




                      9. THE NATURE OF METEORITES


So far in this book we have dealt with meteorites indirectly, chiefly in
connection with their fall, distribution, and recovery. In this chapter,
however, we are shifting our attention to the meteorites themselves, and
will tell what the main types of meteorites are, what meteorites are
made of, what they look like, and how to tell them from ordinary rocks.

First of all, meteorites neither all look alike nor have the same
composition. The general term “meteorite” applies to any mass that
reaches the earth from space. Such masses are made up of metals and
minerals in varying proportions. The term “meteorite” is nearly as
general in meaning as the word “rock,” which geologists apply to bodies,
large and small, that are formed by earth processes and are composed of
various kinds of minerals. Actually, there are almost as many different
kinds of meteorites as there are kinds of rocks; so you can see that in
meteorites a wide range of composition and appearance is possible.

All recognized meteorites belong to one of three main divisions,[7]
_irons_, _stones_, and _stony-irons_.

The irons are composed of an alloy of iron and nickel which may contain
small inclusions of nonmetallic minerals.

    [Illustration: Internal structure revealed when the “etching”
    process is applied to that type of meteorite known as a “granular
    hexahedrite.” See p. 120.]

After a cut section of an iron meteorite has been polished, the flat
surface, except for possible inclusions, is mirror-like and resembles
stainless steel. It appears to be remarkably uniform and uninteresting,
but this appearance is misleading. A characteristic and beautiful
structural pattern develops when such a polished nickel-iron surface is
treated with, for example, a special mixture of nitric acid, alcohol,
and Arabol glue.

This process of treatment is known as “etching.” The different
structural patterns brought out by such etching give us the basis for
classifying the iron meteorites.

If the etching process reveals certain features from which we can infer
a cubic, or 6-faced, crystalline structure, we classify the iron
meteorite as a _hexahedrite_.

If etching produces a certain special pattern from which we can infer an
8-faced, or octahedral, crystalline structure, we recognize the second
subdivision of iron meteorites: the _octahedrites_. This remarkable
pattern was discovered and first described by Alois von Widmanstätten,
of Vienna, in 1808.

The third subdivision of iron meteorites consists of the “structureless”
_ataxites_. (From the Greek for “without arrangement.”) On an ataxite,
etching brings out only a finely granular pattern with a stippled
appearance.

The _stones_ are composed chiefly of minerals that are combinations of
various elements with silicon and oxygen—for example, olivine (Mg,
Fe)₂SiO₄. Meteorites belonging to this division also contain
combinations of elements with oxygen—such as magnesium oxide (MgO) and
aluminum oxide (Al₂O₃). Usually, the stony groundmass contains scattered
specks, grains, and thin veins of the same shiny nickel-iron alloy that
makes up the iron meteorites almost in their entirety.

    [Illustration:                           A. BREZINA & E. COHEN PHOTO
     Widmanstätten pattern which emerges when the carefully polished
    surface of that type of iron meteorite technically known as a “fine
    octahedrite” is “etched.”]

The _stony-irons_, as the name indicates, are an “in-between” division.
Some of the stony-irons, called _pallasites_, are sponge-like but rigid
networks of nickel-iron alloy in which the smoothly rounded openings in
the sponge enclose small gemlike masses of olivine. 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 indeed!

In the _silicate-siderites_, another type of stony-iron, a nickel-iron
matrix is studded with angular fragments, shreds, and splinters of
silicate minerals of all sizes. In the photograph, we can see that each
of the various areas of the nickel-iron matrix (lighter in color)
exhibits its own distinct crystallographic orientation, as is clearly
indicated by the different Widmanstätten patterns.

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 types.

Meteoritic nickel-iron has the following average chemical composition.
To the nearest tenth, this alloy contains: Iron (Fe), 90.9%; nickel
(Ni), 8.5%; cobalt (Co), 0.6%. This alloy gave scientists the key to the
development of commercial stainless steels. It may also contain small
amounts of phosphorous, sulfur, copper, chromium, and carbon.

The average chemical composition of stony meteoritic material is
somewhat more complicated. To the nearest tenth, the “stones” contain:
oxygen (O), 41.0%; silicon (Si), 21.0%; iron (Fe), 15.5%; magnesium
(Mg), 14.3%; aluminum (Al), 1.6%; calcium (Ca), 1.8%; sulfur (S), 1.8%.
The stony material may also contain smaller percentages of nickel,
cobalt, copper, carbon, chromium, and titanium.

    [Illustration:                           A. BREZINA & E. COHEN PHOTO
     Enlarged section of a stony-iron meteorite showing rounded olivine
    grains (dark in color) set in a network of nickel-iron alloy (light
    in color).]

    [Illustration:                           A. BREZINA & E. COHEN PHOTO
     Polished and etched section of a silicate-siderite showing angular
    fragments of silicate minerals (dark in color) imbedded in a
    metallic matrix.]

In the stony-iron meteorites, we analyze the nickel-iron and stony
portions separately. On the average, each of these portions has about
the chemical composition that is given for it above.

Mineralogists have identified a variety of familiar minerals in
meteorites. These include olivine, the plagioclase feldspars, magnetite,
quartz, chromite, and, rarely, microscopic diamonds. All of these
minerals are found here on earth in such igneous rocks as basalts and
peridotites.

On the other hand, the meteoritic nickel-iron alloys (kamacite, taenite,
and plessite, for example) and such meteoritic minerals as schreibersite
(nickel-iron phosphide) and daubreelite (iron chromium sulfide) do _not_
occur naturally on the earth.

We should stress here that although unusual _combinations_ of known
elements are present in meteorites, no new _elements_ have been
discovered during the increasingly intensive study of these masses
during the last 150 years.

The majority of stony meteorites show a structure not found in
terrestrial rocks. These meteorites are made up of rounded, shot-like
bodies called _chondrules_ (from the Greek word for “grain”). The
individual chondrules may vary in size from those as large or even
larger than a walnut down to dust-sized grains. The most common size is
about that of peppercorns. 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 one, they will break with
the rest of the mass, as will sand grains in a quartzite. If the
meteorite is fragile, however, the individual chondrules can generally
be broken out whole. Meteorites containing chondrules are called
_chondrites_.

    [Illustration:        COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Microphotograph of a thin section of a chondrite, showing the
    circular, or nearly circular, cross sections of a number of
    chondrules, including one of large size at the upper edge of the
    section.]

A small percentage of stony meteorites have no chondrules. These
meteorites are known as _achondrites_ (meaning “not chondrites”) and
they resemble terrestrial rocks more closely than the chondrites do.
Some achondrites contain almost no trace whatever of metal, although in
others (for example, the Norton County meteorite, of Chapter 2) small
lumps and specks of nickel-iron are sparsely distributed through the
stony groundmass.

Meteorites are as variable in shape as they are in composition and
structure. Many are cone-shaped; others shield-, bell-, or ring-shaped;
still others pear-shaped. One iron fragment recently recovered from the
Glorieta, New Mexico, fall has been described as “macro-spicular,”
meaning needle-shaped on a very large scale. The photographs opposite
illustrate a number of the commoner forms known. The Glorieta specimen
has been nicknamed “Alley Oop’s shillelagh,” for only a person of great
strength could wield this 13-pounder with ease!

In general, the shape of meteorites depends upon the amount of mass lost
by “evaporation” during passage through the earth’s atmosphere. This
factor, in turn, depends not only upon the speed of transit, 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 meteorite. The ring-shape of the
Tucson, Arizona, iron is believed to have resulted from the “melting
away” of a huge inclusion of stony material during the descent of the
meteorite.

    [Illustration:              CHICAGO MUSEUM OF NATURAL HISTORY PHOTOS
                           (BOTTOM RIGHT) INSTITUTE OF METEORITICS PHOTO
     A few of the many shapes exhibited by meteorites: ring-shaped,
    perforated and highly irregular, pear-shaped, jaw shaped,
    needle-shaped.]

When meteorites are recovered and taken to the laboratory for study, one
of the first things scientists do is to weigh them. If a meteorite is
very large, special scales sometimes have to be constructed for this
purpose. Such was the case for the largest meteorite so far weighed: the
giant Ahnighito, Greenland, meteorite, which Peary brought to New York
City by ship. (See Chapter 3.) A specially constructed scale on which
this huge mass is now mounted gives for its weight about 68,000 pounds.
Other meteorites famous for their great size are: the Bacubirito,
Mexico, 27 tons; Willamette, Oregon, 14 tons; Morito, Mexico, 11 tons;
and the Bendego, Brazil, 5 tons. All of these are irons.

The largest stone meteorite so far recovered as one mass is the
so-called Furnas County, Nebraska, stone, which is the principal
fragment of the Norton, Kansas, fall, and weighs about 2,360 pounds.

At the other end of the size-range, investigators have recovered
meteoritic masses weighing no more than a small fraction of a gram. From
a stone shower that occurred at Holbrook, Arizona, field searchers have
found some of the very smallest specimens in anthills. The insects had
carried these tiny meteorites along with sand and garnet grains in
building their hills!

    [Illustration:        COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     The Willamette iron, famous for its great size and weight (14
    tons), on exhibit at the Hayden Planetarium, New York City. See pp.
    36, 39.]

The only sure way to determine whether or not an object _is_ a meteorite
is to have a small piece of it (say, a fragment the size of an egg)
tested chemically and microscopically by an expert on meteorites.
Nevertheless, there are several questions whose answers will help you to
decide whether or not you are on the right track in suspecting that a
“rock” you have found may be a meteorite:

  Is your specimen especially heavy?

  Does your specimen show a thin blackish or brownish crust on its outer
  surface?

  Does your “rock” have shallow, oval pits on its outer surface?

  If the specimen has a corner knocked off, do you see specks and grains
  of metal on the broken surface?

Is your specimen especially heavy? The iron and stony-iron meteorites
are very heavy. A 1-inch cube of iron meteorite weighs approximately 8
times as much as a 1-inch cube of ice. Even the stones, which are only
about half as dense as the irons, are much heavier than ordinary rocks.

Does your specimen show a thin blackish or brownish crust on its outer
surfaces? You will recall that specimens of both the Ussuri and Norton
meteorites showed a “glaze” of fused material which we call fusion
crust. Most freshly-fallen meteorites are covered with such a crust. To
illustrate how this crust forms, consider a snowball that you bravely
hold in your freezing hand until the outer surface melts. If you then
were to leave the snowball outside overnight, the melted outer surface
would freeze into a hard crust.

    [Illustration: Piezoglyphs (oval pits resembling thumb-prints) in a
    stone meteorite, found at Belly River, Canada. See p. 132.]

In similar fashion, the surface of a meteorite melts during the
blazing-hot part of its flight through the air, only to “freeze” into a
hard, firm coating in the lower, cooler portions of its path. This
hardened coating, the fusion crust, is of much importance. Its presence
is one of the best indications that a “rock” is really a meteorite. From
the character of the fusion crust, experts can piece together a good
deal about what happened to a meteorite on its way down to earth. If you
should be lucky enough to find a meteorite, don’t break off the fusion
crust. A whole encrusted specimen in the hand is worth 200 crustless
fragments scattered at your feet!

Does your “rock” have shallow, oval pits or depressions on its outer
surface? Such features are known technically as _piezoglyphs_ (Greek
_piezein_, to press + _glyph_, to carve) and popularly as
“thumb-prints.” They were formed during the meteorite’s flight through
the atmosphere when the softer portions of its outer shell were “eroded”
away, leaving small scooped-out places. These pittings are very similar
to the prints that would be made by the human hand in a lump of modeling
clay or bread dough. In one case, 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
hand.

If the specimen you have found already has a corner knocked off, do you
see specks and grains of metal on the broken surface? Such scattered
bits of nickel-iron (not to be confused with the shiny mica flakes often
seen in igneous rocks) characteristically occur in the grayish or
brownish groundmass of stony meteorites. If your specimen is unbroken,
hold it lightly against a spinning carborundum wheel or use a file to
grind a small flat surface upon it, and then examine this surface for
specks of metal.

If the answers to these questions are yes, then there is a good
possibility that you have found a genuine meteorite.

If meteorites remain buried in the ground for a long period of time,
their characteristic surface-features may weather away. Under such
conditions, iron meteorites develop heavy-layered coatings of rust (iron
oxide) as much as several inches in thickness. If irons stay in the
ground long enough, they may rust away almost completely and turn into
shale balls, like those found near the ancient Wolf Creek, Australia
meteorite crater. (See Chapter 4.) Stone meteorites buried in the ground
for any great length of time may disintegrate and become completely
unrecognizable as meteorites.

The fact that meteorites of all kinds are attacked by weathering has
always argued strongly in favor of their prompt recovery. In the case of
witnessed falls, prompt recovery is even more important, 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 equipment.




             10. TEKTITES, IMPACTITES & “FOSSIL” METEORITES


Before southern Australia was occupied by the white man, the native
tribesmen of that region treasured certain small rounded pieces of black
glass as medicine stones, rainmaking stones, and message stones. The
Wadikali tribe referred to these objects as _mindjimindjilpara_, a word
meaning “eyes that look at you like a man staring hard.” The early
European settlers of the area called the same black glassy masses
“blackfellows’ buttons.” Both phrases applied to objects that modern
scientists call “australites,” which are now one of the best known types
of _tektites_ (Greek: _tēktos_, molten).

These Australian tektites and the tektites from many other countries
around the world are a problem to meteoriticists. The question is, are
they really meteorites? Many investigators believe that the answer is
yes, and they are inclined to add to the three main divisions of true
meteorites listed in the preceding chapter, a fourth: the tektites.

These mysterious glassy objects occur in such widely separated
localities as Czechoslovakia, the Philippine Islands, Borneo, the Ivory
Coast of Africa, Australia, Indo-China, Texas, Malaya, and Java. In
these and still other areas, they have been found by the thousands in
surface deposits of sand, clay, and gravel.

    [Illustration: (left) “Flanged buttons” from Australia. (right)
    Several sizes of “dumbbells” from Australia. See p. 136.]

Tektites have never been seen to fall. In spite of this fact, as we
noted above, a number of scientists believe that, like the meteorites,
the tektites really did come from outer space but, 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
occurrence.

Tektites are usually quite small, weighing between 1 and 100 grams,
although a few of much larger size have been found. One large specimen
from the Philippines weighed about ½ pound. Two giant tektites, one
weighing ¾ pound and the other over 1 pound, are in the collection of
the British Museum. In composition, tektites are an impure silica-glass
containing low percentages of the oxides of such elements as iron,
magnesium, calcium, and titanium.

If tektite fragments are held under a lamp and observed by reflected
light, their thicker parts generally appear to be jet-black. If,
however, these same specimens are held up _between_ the observer and the
light, then their thin razor-sharp edges are seen to be bottle-green,
yellow-green, brownish, or even colorless.

In shape, many tektites are roundish or oval. Others are shaped like
dumbbells, ladles, canoes, and teardrops. So they are known by those
descriptive terms. One particularly interesting example is the unusual
“flanged button” of Australia. Tektites of this type look like miniature
South American gold-pans, the _bateas_, heaped high with pay dirt.
Australian gold-field workers regarded these tektites as magical, and
used them as good-luck charms. Superstitious American gold-seekers
brought them into the United States all the way from Australia!

    [Illustration: (above) Rounded tektite from Texas. (below) Deeply
    grooved bediasite from Texas.]

Some tektites (for example, many of the “bediasites” from Texas) are
deeply grooved and channeled, and have a very jagged and irregular
appearance. Even the smoother tektite surfaces are characterized by flow
lines, flow ridges, and bubble pits.

Many weathered pebbles and fragments of obsidian somewhat resemble the
tektites superficially. There is a very simple test by which you can
distinguish true tektites from obsidian. If you hold a thin splinter of
tektite glass in a blowpipe flame, the glass melts quietly but only with
the greatest difficulty. On the contrary, when you test in the same
flame the terrestrial glass, obsidian, it froths up much more easily,
into a bubbly, whitish mass.

Although the question of where the tektites came from is still not
entirely settled, most scientists agree that all tektites did have a
_common_ origin. For example, tektites from widely scattered localities
on the earth’s surface show not only similar queer shapes and surface
markings (technically known as “sculpturing”), but also have very much
the same chemical composition and, in particular, the same content of
radioactive elements.

Because the tektites chemically resemble certain terrestrial rocks,
scientists at first believed that some kind of earth process must have
created them. One suggestion was that lightning had fused dust particles
suspended in the air to form them; another, that they had come from
volcanoes; still another, that the tektites were simply inclusions that
had weathered out of terrestrial rocks. A few scientists once took
seriously the possibility that tektites were refuse from primitive glass
factories!

    [Illustration: Tektite vs. obsidian, after blowpipe test.]

While such theories have not yet been completely discarded, most
scientists now feel that the tektites had their origin somewhere outside
the earth. There are several reasons for this belief. First, the shape
of such unusually symmetrical forms as are found, for example, among the
australites, indicates that these small bodies at one time were members
of a swarm of freely-spinning liquid masses. Again, flow features
observed on the surfaces of certain tektites (and the fusion crust
definitely identified on one specimen) show that these bodies at some
time must have traveled through the earth’s atmosphere at high velocity.

If, then, the tektites were not produced by earth processes, where did
they come from? According to primitive legends, they were “rocks” or
“pebbles” from the moon. Indeed, one of the earliest scientific theories
as to their origin (proposed by the Dutch authority Verbeek in 1897)
likewise attributes them to debris jetted out from the moon. Another
holds that tektites are fragments of the outermost glassy layers of some
so-called “meteorite-planet,” or planets.[8] 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 “ices” which make up most of the cometary
nucleus (head) are all distilled away.

These theories of the origin of the tektites are based primarily on
their observed shapes, surface features, and compositions. 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 earth.

To explain this theory, we first recall that the planet on which we live
is more nearly a true sphere than are such familiar “spherical” objects
as baseballs or basketballs. Consequently, 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 circle_.

    [Illustration: Every plane passing through the center of a sphere
    intersects the surface in a great circle. In this figure, only the
    front half of the great circle cut out by the plane is shown.]

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 surface. Mathematics shows that if some earth process had
created the tektites at random over the surface of the earth, then the
odds would be very strongly against the existence of this peculiar
“great-circle distribution.” But such distribution along great circles
would be _expected_ if the tektites had resulted from what might be
likened to “chain-falls” upon the earth of objects like nearby
satellites moving in orbits encircling our globe.

This notion brings up the interesting possibility that at some time in
the remote past, the earth may have been the proud possessor of a set of
equatorial rings. These rings would have been similar to those at
present circling in the plane of Saturn’s equator. (Jupiter, too, may
once have had its own set of equatorial rings.) The rings of Saturn are
known to be made up of countless very small meteorites. In the same way,
the “earth rings” 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 equator.

Eventually, the innermost of these small natural satellites collapsed
onto the earth’s surface, falling along the old equator. At least twice
thereafter, this process was repeated, 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 fall.

As the geologists and other investigators have shown, major shifts have
occurred in the position of the earth’s equator during past geologic
ages. This fact is well-substantiated by discoveries of fossil shells
and plants on the cold Antarctic continent and of glacial deposits in
hot South Africa. Therefore, we could hardly expect the tektite
deposits, which are believed to have fallen at widely separated
intervals of time, to have all occurred along a _single_ great circle on
the earth’s surface.

As you can see, the so-called “tektite-puzzle” is a complex one. As if
this were not bad enough, 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
tektites, but also having other features in common with the tektite
glasses.

At Mount Darwin in Tasmania and at Wabar in the Rub’ al Khali desert of
Arabia, large and small fragments of this curious silica-glass have been
collected. At Wabar the masses of silica-glass were found in and about
the rims of a series of meteorite craters formed in nearly pure sand, as
we pointed out in Chapter 4. These meteorite craters are known to have
resulted from the high-speed impact of iron meteorites upon the sand
dunes of the Wabar site. 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
craters, 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 impact. Consequently, it is natural that these
Wabar masses of congealed silica-glass and nickel-iron be called
_impactites_. They are silica-glasses, created chiefly from
_terrestrial_ materials by the impact of large crater-forming
meteorites. This same name is now applied to all silica-glasses believed
to have the same origin as those at Wabar.

As regards size if not composition, 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 tektites.
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 swarms.

In addition to the curious puzzle of the tektites, meteoriticists have
also run up against the problem of “fossil” meteorites or, more exactly,
the problem of the _lack_ of “fossil” meteorites. As we have already
mentioned, no positively identified meteorite has ever been found in
other than the most recent rock layers. With all the mining—particularly
coal mining—that has gone on throughout the world in historic times,
this fact does seem astonishing.

A number of explanations can be suggested for this absence of ancient
meteorites. In the geologic past, meteorite falls may not have occurred
as often as they do today. For example, 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 ground. Again, even if the rate of infall of
meteorites was the same in the remote past as now, 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 are.

Several unusual lumps of rock from England and a mass of iron from
Austria, all found at some depth by coal miners, have been tentatively
put forward as “fossil” meteorites. But studies of these masses have so
far produced no conclusive results. Still, we should not ignore the
possibility that someday meteorites may be found and identified in rocks
of considerable age.

    [Illustration:                                   L. J. SPENCER PHOTO
                          COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Mysterious glass objects found in the Libyan Desert. (right) Cut
    and polished specimens.]

Does it seem as if we have posed more problems than we have solved in
this chapter? It is very true that we have done just that. In speaking
briefly about the tektites, the impactites, and the absence of “fossil”
meteorites, 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 solve. Perhaps you will find here the
kind of unusual and thought-provoking problems that make the study of
meteorites a rather special challenge. If so, you may wish to take an
active part someday in unraveling these puzzles.




                        11. OMENS AND FANTASIES


Men seem to have always taken an interest in meteorites, but not until
the early nineteenth century were these objects considered to be worth
preserving for _scientific_ study.

In the beginning, people believed that because meteorites fell from the
heavens, they were either gods themselves or messengers from the gods.
The more civilized of early men therefore carefully kept the fallen
meteorites. They draped them in costly linens and anointed them with
oil. In many instances, the people built special temples in which
meteorites were actually worshipped. Some of the holy stones of the
ancients, such as the Diana of the Ephesians, mentioned in the Bible as
“the image which fell down from Jupiter,”[9] are now thought to have
been meteorites.

Meteorite worship was common long ago in the Mediterranean area and in
Africa, India, Japan, and Mexico. This practice still persists in some
regions even in modern times. The Black Stone of the Kaaba, for example,
has been sacred to all Mohammedans from about 700 A.D. right up to the
present. It is said to be a meteorite although this fact has never been
verified, because strict religious taboos connected with the stone
prevent any scientific examination or study of it. On the contrary, the
Andhâra, India, meteorite is known to be a genuine one. 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 times.

At about 4:00 in the afternoon of December 2, 1880, the people of
Andhâra heard a noise like that made by a gun. Some of the villagers saw
a “dark ball” come to earth in a field near them. This falling object
sent up a small cloud of dust as it struck the ground. After the stone
had been recovered from the field and the dust had been washed from its
surface, 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 displayed.

The scientist who promptly investigated the Andhâra fall reported that
throngs of worshippers were crowding into the as yet unfinished brick
temple to make offerings of flowers, sweetmeats, milk, rice, water, bel
leaves, and of course money. The stone had been named Adbhuta-Nâth, “the
miraculous god.” It was shaped like a round loaf of blackish bread and
weighed an estimated 6 pounds. The scientist was not allowed to touch
it, but he got close enough to verify that the stone was a meteorite
covered with a typical blackish fusion crust.

Not only has man worshipped meteorites, but during a period extending
from approximately 300 B.C. to 300 A.D., emperors and self-governing
cities frequently marked the fall of meteorites by minting special coins
or medals known as _betyls_.[10] One of these is the betyl of Emisa,
Syria, made by Antonius Pius (138-161 A.D.). The historian, Herodotus,
accurately described the object honored by this betyl as: “A large
stone, which on the lower side is round, and above runs gradually to a
point. It has nearly the form of a cone, and is of a black color.
_People say of it in earnest that it fell from Heaven._” The stone is
shown on the coin as carried on a quadriga (a carriage drawn by four
horses) under a canopy of four sunshades.

    [Illustration:        COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Drawing of multiple fireball, over Athens, October 18, 1863. J. F.
    J. Schmidt, the celebrated pioneer fireball observer, described it
    as a mass of dazzling light “bringing into view land and sea, with
    the Acropolis and the Parthenon a mile away across the city.”]

Many ancient peoples held meteorites in great reverence, particularly if
they were seen to fall. But at the same time, other more
practical-minded individuals made good use of the durable and easily
worked alloy provided by nature in the nickel-iron meteorites. This
alloy was frequently used to make ax-heads, spear and harpoon points,
knives, farming tools, stirrups and spurs, and even pots and other
utensils. Archeologists have found earrings and similar ornaments
overlaid with thin sheets of hammered meteoritic iron in Indian mounds
of the Ohio Valley. They have also discovered round beads made of
nickel-iron in Indian mounds of the Havana, Illinois, area and in the
still more ancient Egyptian ruins at Gerzah.

Meteoritic iron has often been used in the manufacture of special
swords, daggers, and knives for members of the royalty. Atilla and other
early conquerors of Europe boasted of “swords from heaven.” Emperor
Jehangir (1605-1627) ordered two sword blades, a knife, and a dagger to
be smelted from the Jalandhar, India, meteorite, which fell on April 10,
1621. In the early nineteenth century, a sword was manufactured from a
portion of the Cape of Good Hope meteorite for presentation to
Alexander, the Emperor of Russia. Even as late as the end of the
nineteenth century, several swords were made from a part of the
Shirihagi, Japan, iron meteorite at the command of a member of the
Japanese court.

    [Illustration: A Russian artist’s pen-and-ink drawing of an
    extremely brilliant detonating fire ball or bolide. See page 102.]

In the Europe of the Middle Ages, meteorite falls and meteor showers, as
well as other “unnatural” events like comets, eclipses, and displays of
the aurora borealis, were regarded with superstitious awe by commoner
and king alike. The medieval mind always sought to interpret events
connected in any way with the heavens as somehow influencing the affairs
of men. A bishop explained that the great meteor shower of April 4,
1095, forecast “the changes and wanderings of nations from kingdom to
kingdom.” The fact, however, that the First Crusade began within a year,
is mere coincidence.

In referring to celestial events, Shakespeare often expressed the view
that was common in the Middle Ages and the Renaissance. An example is:

  The bay-trees in our country are all wither’d
  And meteors fright the fixed stars of heaven;
  The pale-faced moon looks bloody on the earth
  And lean-look’d prophets whisper fearful change,
  . . . . . .
  These signs forerun the death or fall of kings.
                                        (_Richard II_, II, iv, 8-11, 15)

Yet the descent of meteorites from the heavens was not always regarded
as a forewarning of bad fortune. On November 16, 1492, a 279-pound
meteorite fell at Ensisheim in Alsace, not far from the battle line
separating the armies of France and the Holy Roman Empire. Emperor
Maximilian, the leader of the Empire’s forces, commanded that the fallen
stone be carried to his castle. There a formal war-council was held to
determine what the strange event could mean.

    [Illustration:        COURTESY OF AMERICAN MUSEUM OF NATURAL HISTORY
     Drawing of Andromedid meteor shower, November 27, 1872.]

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 Empire. After breaking off two
small pieces of the stone, one for the Duke of Austria and one for
himself, the Emperor forbade further damage to it. He also gave orders
that the stone be hung in the parish church in Ensisheim for all to see.
In this way, 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 leader.

The discussion to this point makes clear that in ancient, medieval, and
Renaissance times, meteorite falls were considered as startling and
disturbing events, which frequently were interpreted in strange and
mistaken ways. But the fact that meteorites actually did fall from the
heavens was not questioned. As the so-called “Age of Reason” opened, a
curious change in attitude toward meteorite falls took place.

At the very time that knowledge in general increased, men of learning
began to deny that meteorite falls occurred at all! The scientists of
the French Academy, in particular, were very positive on this point.
Since the era was one in which all Europe sneezed if “la belle France”
had a cold in the head, it was a trying time not only for the early
meteoriticists, but for all who had the nerve to insist they had seen
rocks fall from the sky.

By the end of the 1700’s, the authorities had studied the evidence
relating to meteorite falls and had completely rejected it. They said
that there was no “proof” whatever that “stones fell from the heavens.”
These early scientists openly sneered at people who claimed that they
had seen meteorites fall. It was felt that the spectators of such events
either had merely been “seeing things,” or had surely been reporting
light and sound effects connected with nothing but ordinary
thunderstorms.

When confronted with the “fallen” masses themselves, the authorities
often refused to examine them, or if they did, insisted that these
masses were only rocks that had been struck by lightning. Such were the
opinions of learned men around the close of the eighteenth century.

Fortunately, scientific facts have a stubborn way of winning out in the
long run. A major part of the credit for seeing that the truth regarding
meteorite falls was at last recognized must go to E. F. F. Chladni, a
German physicist, and to Edward Howard, an English chemist.

In 1794, Chladni published an extremely important paper concerning a
large spongelike mass of “native iron” found near Krasnoyarsk, Russia.
This object had been discovered in 1749 by a Russian blacksmith, and it
was studied in 1772 by P. S. Pallas, an early traveler. Chladni
concluded that the mass of iron[11] must have fallen from the heavens,
because it had been “fused” (but not by man, electricity, or fire) and
also because there were no volcanoes anywhere around its place of find.

Chladni supported his theory by listing numerous reports of meteorite
falls dating from ancient and medieval times. But Chladni’s fellow
scientists flatly rejected his theory as clever but not satisfactory.

With the fall of the Siena meteorites in Italy on June 16, 1794, the
controversy regarding the possibility that stones actually fell from the
sky became particularly heated, and remained so for nearly ten years.
During this interval, two other important meteorite falls occurred: Wold
Cottage, England, on December 13, 1795, and Benares, India, on December
19, 1798. Scientists had a hard time finding explanations for these
well-observed events, and some of the theories put forward to account
for them far outdid Chladni’s in “cleverness,” if that be the correct
word.

One scholar, writing in 1796, suggested that the masses which fell at
Siena resulted from the solidification at great height of volcanic ashes
from Mount Vesuvius. These ashes had supposedly been carried northward
beyond Siena and then been “brought back by a northerly wind, congealing
from the air....”

Fortunately, in 1803 Edward Howard’s chemical work on meteorites came to
a successful conclusion. This patient chemist made analyses of samples
from the Siena, Wold Cottage, and Benares falls and from an older
Bohemian fall. He also had the samples studied mineralogically by a
fellow scientist. From the results of these investigations, he drew the
following conclusions, which admirably supported Chladni’s well-reasoned
and thoroughly documented theory regarding meteorite falls:

  All four of the stones studied had very nearly the same composition.

  Despite the fact that the stones contained no new elements, their
  mineralogical character differed in several important respects from
  that of any rocks found naturally on the earth.

  The four masses must have had a common origin although their reported
  falls had been widely separated both in time and in space.

  Finally, said Howard, it was quite possible that the stones had really
  fallen from the sky.

Howard’s views were soon put to the test. Shortly after the publication
of his important paper, a shower of stony meteorites fell near L’Aigle,
France, on April 26, 1803. This event was carefully investigated by
French scientists, and they reluctantly admitted that about 3,000 stones
actually had fallen within an oval-shaped area about 6 miles long by 2
miles wide. 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 Chladni, effects now recognized as characteristic
of the infall of meteorites upon the earth. The evidence was
overwhelming—stones really did fall from the sky. In the camp of the
enemy, so to speak, the reality of meteorite falls was established once
and for all!




                          12. THE MODERN VIEW


After the L’Aigle shower of 1803, a whole new era opened in the study of
meteorites. No longer did scientists hold these objects up to ridicule
and scorn. Instead, they came to regard meteorites as well worth
collection and careful study.

The Vienna Museum, the British Museum, the Paris Museum, the Academy of
Science of St. Petersburg (now Leningrad), and the U.S. National Museum
began to build up splendid meteorite collections. Scientists in Germany,
England, France, and Russia engaged in the painstaking mineralogical
study and classification of individual meteorite specimens.

The modern science of meteoritics is rooted deep in the nineteenth
century. Many special fields of investigation had their beginnings then.
Scientists became interested in the chemistry, the mineralogy, and the
metallurgy of meteorites; in the orbits of meteorites and the
trajectories they follow through the earth’s atmosphere down to impact
with the ground; and in the distribution of meteorite falls in space and
time.

From this period we can date such milestones of progress in meteoritics
as:

  The discovery of the beautiful and significant Widmanstätten patterns
  characteristic of the majority of the irons, and the less spectacular
  but equally important lines named for J. G. Neumann, the German
  meteoriticist who discovered them, in 1848, in the Braunau meteorite.

  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 earth, and perhaps of the
  Solar System and the wider cosmos as well.

  Tentative explanations of the violent and terrifying light and sound
  effects connected with meteorite falls.

  Tentative explanations of such oval-shaped areas as shown above.

    [Illustration: Typical distribution of meteorite fragments according
    to size, within oval-shaped area of fall. The larger masses of the
    shower carry farther on, in the direction of the motion of the
    meteorite. As early as 1814, investigators had noted this
    peculiarity of meteorite-shower distributions. See pp. 32, 89, 94.]

By 1850, A. Boisse, an early French geologist and meteoriticist, had put
forth the basic _meteorite-planet_ hypothesis. According to this theory
of his, meteorites are the fragments of a planet[12] that formerly
orbited between Mars and Jupiter in what is now called the “asteroid
belt.” And untold millions of years ago, this planet was shattered by
some unknown but very great force, possibly collision with another
celestial body.

The structure of the meteorite-planet was considered to have been very
much like that of the earth. The various divisions of recognized
meteorites were believed to be representatives of the several
concentric, or nested, shells of material originally making up the
destroyed planet. These shells were progressively less dense with
increasing distance from the center of the planet.

Today Boisse’s theory is one of the most widely accepted as an
explanation of at least one major category of the meteorites. Some
modern investigators would insist that the meteorite-planet had a thin
outer glassy shell from which the tektites came.

Most of the larger fragments of the meteorite-planet, now called the
_asteroids_, move so that the average asteroidal orbit very closely
approximates the orbit of the original planet. But many of the smaller
fragments follow paths in space that differ considerably from the
original meteorite-planet’s orbit. Even some of the asteroids behave
this way, either because of the high speeds they acquired at the time of
disruption of the meteorite-planet, or because of the later influence of
the major planets and particularly of the giant planet, Jupiter.

    [Illustration: A diagram (not drawn to scale) showing position of
    asteroid-belt with respect to the orbits of Mars and Jupiter. The
    asteroids with average orbits move within this belt. The non-typical
    asteroid indicated follows an orbit that brings it well inside that
    of the earth. There are a number of asteroids with such peculiar
    orbits. 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 crater.]

In fact, at the present time, several asteroids move well within the
orbits of the earth and Venus. It is quite possible therefore that such
a large meteorite crater as the one at Canyon Diablo, was produced by
the prehistoric fall of one of these small members of our Solar System.
If so, we have reason to believe that a core-fragment of the
meteorite-planet came to earth at Canyon Diablo. 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-iron, which in all likelihood was core material.

The lengthy and costly series of mining operations at Canyon Diablo were
all undertaken in the hope of locating the “main mass” of this huge
projectile and thus of opening up what might be called a cosmic-lode of
quite valuable metals. Unfortunately, the miners overlooked the fact
that impacts at meteoritic speeds produced almost incredible amounts of
heat. Even the solid iron meteorites are vaporized and widely dispersed
at the temperatures resulting from such impacts, as we have seen was the
case at Wabar (see Chapter 4). So it was at Canyon Diablo.

The idea of a cosmic-metal mine might at first strike some readers as
too futuristic to take seriously. But the necessity for catching a
core-fragment before it enters the consuming atmosphere of our planet is
really nothing new. As far back as 1939, the senior author had occasion
to point out that if we wish to start a successful cosmic-metal mine, we
must catch our core-fragment before it is turned into unminable vapor.
This point will come up again in the next chapter.

    [Illustration: Cross-section of Boisse’s hypothetical
    meteorite-planet. Fragmentation of this sphere was believed to have
    given rise to the following divisions of meteorites:

    The _iron_ meteorites came from A, the dense nickel-iron core.

    The stony-iron meteorites came from B, the intermediate zone of
    cellular nickel-iron and silicate minerals.

    The _stony_ meteorites came from C, the outer zone of silicate
    minerals in which relatively little or no nickel-iron is present.
    The chondrites were believed to come from the inner portion of this
    zone; the achondrites, from the outer portion.]

There are several other theories of the origin of meteorites interesting
enough to mention. 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 grounds. On the other hand, extremely
violent _primordial_ volcanoes on the earth (not the weak ones of
historic times, like Aetna or Vesuvius) could have ejected material that
in much later times fell, and continues to fall back on our globe. This
theory has not been ruled out and it still receives support, for
example, from some authorities in the U.S.S.R. These same Russian
scientists take most seriously a suggestion that the meteorites (and
comets as well) were thrown out by volcanoes believed to exist on the
planet, Jupiter—a theory dating back almost a century to the English
astronomer, R. A. Proctor.

Some scientists believe that meteorites represent the congealed remains
of gaseous bolts of matter ejected by the sun. Others interpret them as
fragments of comets that have been torn apart by passing too close to
the sun, which is the most powerful gravitational center in the Solar
System.

Chemists, geologists, astronomers, and physicists—as well as the
meteoriticists themselves—are constantly working toward a solution of
the problem of the meteorites. Where do these bodies come from? What can
we learn from them about their age and origin and about the age and
origin of our Solar System? Years may be required, but eventually the
riddle of the meteorites will be solved by the patient, concerted
efforts of men and women of science.

    [Illustration: Collapsed mine buildings in the bottom of the Canyon
    Diablo meteorite crater. A shaft was put down here in one of several
    unsuccessful attempts to locate the main mass of the meteorite. See
    pp. 44-52.]




                  13. PRESENT AND FUTURE APPLICATIONS


So far we have considered what might be called the “pure” rather than
the “applied” side of the study of meteorites. The investigator in any
pure science asks of a new discovery, “What does this tell me about the
universe? How does it better help me to understand the laws of nature?”
Of the same discovery, however, the worker in an applied science will
ask, “What practical use can be made of this gain in knowledge? What can
it be made to do for mankind in general?”

These questions reveal a decided difference in viewpoint, but this
difference does not reflect unfavorably on either class of scientists.
In fact, there is a great deal of truth in the saying “Today’s pure
science is tomorrow’s applied.” Actually, ways and means of taking
advantage of seemingly useless scientific discoveries are constantly
being found. 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 relativity. Here the seemingly mystic formula E
= mc² came to have far-reaching practical applications indeed!

Meteoritics has some exceedingly practical applications. Far from being
completely “out of this world”—as the recovered meteorites themselves
originally were—this science has been and can be made to serve mankind
in a number of rather unexpected ways. Meteoritics, the onetime
“stepchild of astronomy,” is currently being regarded with
ever-increasing respect by scientists and engineers working in many
different fields.

Consider, first of all, the stainless steels that are so widely used in
modern industry, and even the fine satin-sheen stainless “silverware”
that graces our dining tables. These have wisely been patterned after a
natural alloy with lasting qualities of strength, tenacity, and
resistance to corrosion. This natural alloy is the one making up the
iron meteorites.

Its toughness and durability became well known wherever attempts were
made to section these metallic meteorites. Specially designed and
extra-powerful sawing equipment is required to slice meteoritic iron,
and even with it, progress is painfully slow. 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 “meteor steel,” which
mimicked the composition of the iron meteorites.

Of course, 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 material. Every precaution is taken to keep the
amount of “sawdust” to a minimum, for such finely ground up and
contaminated meteoritic material is of little scientific use. And, in
addition, scientists must guard against heating meteorites to high
temperatures because such heating destroys the delicate internal
structure of the masses. If these two considerations (loss of material
and overheating) were unimportant, even a large meteorite could easily
be divided up by use of such high-powered oxyacetylene torches as are
used to dissect huge obsolete battleships.

At the Institute of Meteoritics, a thin, water-cooled blade of soft iron
is driven slowly back and forth by an electric motor. Carborundum grit
in water suspension is fed evenly into the narrow cut over its entire
length. This grit becomes imbedded in the lower edge of the soft iron
blade, which then acts as a “many-toothed” metal saw. Several meteorites
can be sectioned simultaneously by this multiblade saw. In the future,
such newly developed methods as high-speed particle jet streams or
ultrasonic devices may be used to section meteorites both rapidly and
economically.

In the field of cosmic ray studies, particularly those concerned with
the protection of space travelers from harmful radiation, meteoritics
can be of help. The recovered meteorites have already come through those
regions that would be crossed by even the farthest-ranging spaceships.
Consequently, 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-shield.

The first study of this type was made in May, 1948, at the Institute for
Nuclear Studies of the University of Chicago (now the Enrico Fermi
Institute). 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 question. In October, 1949, English investigators
ran similar tests at the Londonderry Laboratory for Radiochemistry,
Durham, England, on samples of the freshly fallen Beddgelert, North
Wales, meteorite discussed on pp. 69-70. The results of these two
pioneer studies were negative because the “Model-T” instruments
available in 1948 and 1949 were not sensitive enough to detect the
relatively low radioactivities present.

    [Illustration: The 6-blade meteorite gang-saw in the machine shop at
    the Institute of Meteoritics.]

In 1955, however, scientists at Purdue University, using more refined
counters, studied small nuggets of nickel-iron, also from the Norton
meteorite. This time, the results of the radioactivity tests were
positive. The investigators detected tritium (an isotope of hydrogen
produced by cosmic-ray bombardment) in the samples. Furthermore, 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 possible. “Forewarned is forearmed,”
and from the standpoint of future astronauts, this is as practical a
result as one could wish for!

In the relatively near future, men will certainly land on the surface of
the moon. 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
space. The nearly airless moon, like the meteorites, has also been
exposed to very intense cosmic radiation for a long time. 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 surface.

Suppose that extra-sensitive instruments were designed to pick up and
measure the radioactivities. Suppose further that these instruments were
mounted in a space-probe put in an orbit circling closely about the
moon. Plans for such a project are now under way. What types and
intensities of lunar radioactivities might such probe-mounted
instruments record?

Until such a space-probe becomes available, earth-bound space-scientists
are seeking at least a preliminary answer to this question. They are
doing this by investigating the natural “probes” that have come to us
from space—the meteorites.

Investigators have undertaken such studies very recently by employing a
new radiometric method technically called _gamma-ray spectroscopy_. Work
of this sort has been and is being done at the Los Alamos, New Mexico,
Scientific Laboratory on scores of meteorite and tektite specimens
loaned to the Laboratory by the Institute of Meteoritics. Some of the
individual meteorite specimens tested weighed as much as 37 pounds, and
are probably the largest single extra-terrestrial masses yet tested for
cosmic ray-induced radioactivities.

Let us turn now to another important application of meteoritics. Any
body in motion through the air or in space has a “striking power” of
sorts. For some objects, this striking power, which is technically known
as _ballistic potential_, is very weak, as in the case of silky
milkweed-down drifting through the air. Hailstones have a good deal more
striking power, as may have been painfully demonstrated on your own
head. And, finally, such masses as falling meteorites (and especially
those orbiting in space, unretarded by atmospheric resistance) have an
extraordinarily formidable ballistic potential. This is because
meteorites are not only tough and dense, as good projectiles must be,
but are also moving at high velocities—particularly high if the
meteorites come into the Solar System from interstellar space.

For this reason, the speeds of meteorites are very important to
scientists responsible for rocket flights and for keeping satellites
aloft over long periods of time. Clearly, these men must have as
accurate information as possible on where and how fast meteoritic
particles are moving, so as to chart the safest routes for spaceships,
and to develop satisfactory means of protecting rockets and satellites
against the effects of bombardment by the smaller meteorites. For these
“small-fry” cosmic missiles are so numerous that many of them are sure
to be encountered even in brief flights outside the earth’s atmosphere.

Such information might also prove valuable in the future to the crews of
spaceships on long flights into deep space. Such men may face the life
or death problem of taking successful “evasive action” against giant
meteorites that will seem like flying hills and mountains.

A strong parallelism exists between a meteorite fall and the re-entry of
a nose-cone or data-capsule into the atmosphere. To a considerable
extent, the difficult problems connected with the latter are being
attacked at present through careful studies of meteorites. From the
air-sculptured shapes of meteorites, their crustal flow patterns, and
the thicknesses and types of fusion crusts they show, scientists are
learning a great deal about certain factors connected with the re-entry
problem. These factors include rate of vaporization, effects of extreme
temperatures, and types of sculpturing to be expected as a result of
encountering the resisting molecules of the atmosphere.

    [Illustration: Relationship between (A) the trajectory of a falling
    meteorite, and (B) the re-entry stage of a V-2 rocket. The solid
    lines indicate the similar portions of the two trajectories.


  A. A METEORITE FALL
  B. A V-2 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 exhausted. The population of the earth is increasing at a mad
pace, and an end to metal-consuming wars is still not in sight. The need
for such metals can only become more and more acute.

According to one of the currently favored explanations of the origin of
the meteorites, 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 crater. If this meteorite-planet hypothesis
finally wins general acceptance, 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 sort. Once he has given an answer, the space
engineers will take over, and mining operations will be started on the
unlimited sources of essential metals to be found in outer space.

Initially, no doubt, metal recoveries will be freighted back to earth in
rocket-load lots. But as the need for iron and nickel increases on a
metal-hungry earth, vast engineering projects may well be undertaken to
“snare” the larger metal meteorites and equip them with rocket motors.
This will be done so that by use of rocket power, the natural orbits of
the meteorites can be changed into orbits bringing them back to earth.
Unlike the natural, uncontrolled Canyon Diablo meteorite fall that
vaporized what would have been a rich nickel-iron deposit, the
rocket-controlled meteoritic “metal mines” will be eased down to earth
all in one piece.

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 dangerous,
often uncharted seas in search of the great whales. The rocket crews of
day-after-tomorrow will no doubt be equally fearless and resourceful as
they navigate the sea of space, intent on capturing the great “metal
mines” of the future.

The experience gained in such space-mining ventures will then be carried
over into expeditions to ensnare the larger stony-iron meteorites. These
masses of iron and stone will offer less favorable mining possibilities,
but they can be turned into rocket-propelled and guided de luxe
space-cruisers. By this term, we do not mean that these natural
space-ships will house all the luxuries of the ocean-liners advertised
in the travel magazines. Rather, we see them as providing roomy,
comfortable “underground” living quarters. Furthermore, their occupants
will be adequately protected by great thicknesses of metal and rock from
the injurious radiations of empty space, and the meteorites that make
the term “empty space” something of a misnomer.

Initially, 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 earth.

Later on, these meteorites-turned-into-space-ships may be used to
explore the dangerous and faraway corners of the Solar System, since the
very substance of each massive meteoritic rocket-body will serve as an
adequate and handy source of fuel supply.

When men have learned to live on such “homes away from home,” it is
quite possible that the larger of these modified meteorites, after their
interiors have been opened up for occupancy by the inroads of the
fuel-hungry rocket-motors, may be steered into neighborly orbits about
old Mother Earth. Here, these “natural” 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 future.

People who live in these super-urban outliers of Mother Earth may take
the same pride in their natural, if converted, homes as many former city
dwellers now take in the old-fashioned sprawling farmhouses they have
rebuilt and occupied. Perhaps one of your descendants will live in such
a meteorite-orb, 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 instinct.
Who knows!




                          FOR FURTHER READING


If you are especially interested in meteoritics, you already may have
read some good books on general astronomy. There are many and most of
them are not too advanced for the beginner. Unfortunately, these books
devote but little space to meteoritics, the “Johnny-come-lately” of
astronomy. Almost all of the writings on meteors and meteorites you will
find largely profitable to read are in professional meteoritical
publications. A selected list of such publications, containing much or
at least a worthwhile amount of material you will now be able to
understand, is given below. Your chief difficulty in using this list
will be in finding some of the more important items in the holdings of
your public library, unless it is a large and well-stocked one. Your
librarian, however, may be able to help you get the item from some other
library—perhaps from that of a nearby university or college.


                           METEORIC ASTRONOMY

MEBANE, A. D. “The Canadian Fireball Procession of 1913, February 9,”
_Meteoritics_, Vol. 1, No. 4 (1956), pp. 405-421. Eyewitness accounts of
the most famous fireball procession on record.

OLIVIER, C. P. _Meteors_, Williams and Wilkins, Baltimore, 1925. An
exhaustive survey of work done by visual meteor-observers.

SCHIAPARELLI, G. V. _Shooting Stars_, a translation by C. C. Wylie and
J. R. Naiden, published in the _Proceedings, Iowa Academy of Science_,
Vol. 50 (1943), pp. 48-153. A pioneer treatise, dated 1867, which is
basic to later work in this field.

WHIPPLE, F. L. “Photographic Meteor Studies, I,” _Proceedings, American
Philosophical Society_, Vol. 79, No. 4 (1938), pp. 499-548. Fundamental
paper on the subject. Of the six meteors analyzed, five followed
elliptical orbits and one, a strongly hyperbolic orbit.


                               METEORITES

FARRINGTON, O. C. “A Catalogue of the Meteorites of North America to
January 1, 1909,” _Memoirs, National Academy of Sciences_, Vol. 13
(1915). Contains fascinating accounts of the phenomena connected with
meteorite falls, interspersed with lengthy technical chemical and
microscopic studies of meteorites.

FARRINGTON, O. C. _Meteorites_ [published by the author], Chicago, 1915.
The classic American work on meteorites. The first half of the book is
popular; the last half is technical.

HEY, M. H. and PRIOR, G. T. _Catalogue of Meteorites_, William Clowes &
Sons, London, 1953. An exhaustive catalog of all recognized and also,
unfortunately, of many doubtful meteorite falls and finds, from the
beginning of the historical record up to December 1952.

LAPAZ, LINCOLN. “The Achondritic Shower of February 18, 1948,”
_Publications, Astronomical Society of the Pacific_, Vol. 61 (1949), pp.
63-73.

LAPAZ, LINCOLN. “The Effects of Meteorites upon the Earth,” _Advances in
Geophysics_, Vol. 4, edited by H. E. Landsberg, Academic Press, New
York, 1958, pp. 217-350. A monograph covering such topics as meteorite
hits upon buildings and people, meteorite detectors, and the nature and
age of meteorite craters.

LEONARD, F. C. “The Furnas County, Kansas, Achondritic Fall (1000,400),”
_Contributions, Meteoritical Society_, Vol. 4 (1948), pp. 138-141. This
paper and the eighth item, above, discuss the phenomena of the fall of
the largest aerolite so far recovered anywhere in the world.

MERRILL, G. P. “The Story of Meteorites,” _Minerals from Earth and Sky_,
Vol. 3, Part I, Smithsonian Scientific Series, 1929, pp. 1-163. A
chiefly popular survey of the subject by a master meteoriticist.

PERRY, S. H. _The Metallography of Meteoric_ [meteoritic] _Iron_, U. S.
National Museum Bulletin No. 184 (1944). A summary of knowledge on the
subject, supplemented by exceptionally fine photographs of etched
meteorite sections.

SWINDEL, G. W., JR., and JONES, WALTER B. “The Sylacauga, Talladega
County, Alabama, Aerolite: A Recent Meteoritic Fall that Injured a Human
Being,” _Meteoritics_, Vol. 1, No. 2 (1954), pp. 125-132.

WHITE, C. S. and BENSON, OTIS O. (editors) _Physics and Medicine of the
Upper Atmosphere_, University of New Mexico Press, Albuquerque, 1952.
See Chapter X, “Meteoritic Phenomena and Meteorites,” by F. L. Whipple,
pp. 137-170; and Chapter XIX, “Meteoroids, Meteorites, and Hyperbolic
Meteoritic Velocities,” by Lincoln LaPaz, pp. 352-393. Modern views on
the meteorite velocity controversy.


                           METEORITE CRATERS

LAPAZ, LINCOLN. “The Craters on the Moon,” _Scientific American_, Vol.
181, No. 4 (1949), pp. 2-3. A popular exposition of the
Bénard-Wasiutynski theory of the origin of the ordinary (nonrayed)
craters on the moon.

SPENCER, L. J. “Meteorite Craters as Topographical Features on the
Earth’s Surface,” _Geographical Journal_, Vol. 81 (1933), pp. 227-248.
The classic paper on terrestrial meteorite craters.


                            METEORITIC DUST

BUDDHUE, J. D. _Meteoritic Dust_, The University of New Mexico Press,
Albuquerque, 1950. An account of the various techniques used in
collecting and studying meteoritic dust; and also of the conclusions
drawn from the study of such dust.




                                 INDEX


                                   A
  achondrites, 126, 163, 178
  Adelie Land stone, 78
  Adrar iron, 38, 40
  aerolites, 178, 179
      _see also_, stones, meteoritic
  age of meteorites and/or craters, 50, 52
  Aggie Creek iron, 76
  Ahnighito iron, 36, 128
  Algoma meteorite, 75
  “Alley Oop’s shillelagh,” 126
  altitude, 88, 90, 105, 106
  American Meteor Society, 116
  American Museum of Natural History, 37
  Anderson Township meteorites, 76
  Andhâra stone, 147-8
  Andromeda, Great Spiral Nebula in, 2
  Andromedid shower, 153
  anthills, meteorites in, 128
  anti-matter, 58-60
  Aouelloul crater, 65
  appearance and disappearance of meteors, 86, 94, 106
  applied science, 166
  archeologists, 76, 150
  areas of fall, 13-4, 24, 26, 32, 89, 94, 159
  armor plate, 167
  asteroid belt and orbits, 160-1
  astronautics, 110, 168, 170-6
  ataxites, 120
  Athens, multiple fireball over, 149
  australites, 134, 140
  azimuth, astronomical, 88


                                    B
  Bacubirito iron, 128
  Bald Eagle iron, 76
  ballistic potential, 171
  Baxter stone, 73
  Bear Lodge iron, 76
  Beddgelert stone, 69-70, 73, 168
  bediasites, 136, 137
  Belly River stone, 131
  Benares meteorite, 156
  Bendego iron, 128
  Benld stone, 73
  Benson, O. O., 179
  Bethlehem stone, 73
  betyls, 148, 150
  Bible, meteorite mentioned in, 147
  Bielid shower, 116
  “blackfellows’ buttons,” 134
  Black Stone of the Kaaba, 147
  Boisse, A., 160, 163
  bolides, 102, 151
  Braunau iron, 73
  Brenham craters and meteorites, 52, 65, 66, 78
  Box Hole Station crater, 65
  Bridgewater meteorite, 75
  British Museum, 136, 158
  Buddhue, J. D., 179


                                    C
  Campo del Cielo craters, 50, 65
  Canyon Diablo crater, 44-52, 65, 66, 75, 96, 161, 162, 165, 174
  Cape of Good Hope iron, 150
  Cape York iron, 36, 37
  Carlton meteorite, 75
  Casas Grandes iron, 76
  charms, meteorites used as, 134, 136
      _see also_ sacred meteorites; superstitions
  Chesterfield meteorite, 75
  Chladni, E. F. F., 155-7
  chondrules and chondrites, 124-6, 163
  Chubb crater, 52-4
  coins depicting meteorites, 148, 150
  collection of meteorites in institutions, 20, 32, 34, 37, 38,
          40-1, 90, 136, 158
  comets, 114, 140, 164
  composition of meteor-forming particles, 160-7
  composition of meteorites, 118-26, 163, 179
  composition of tektites, 136-8
  Constantia stone, 74
  contraterrene matter, 56, 58-60
  convection-current hypothesis, 63-4
  cosmic metal mine, 162, 174-6
  cosmic rays, 168-71
  craters, 17, 18, 20, 42-65, 66, 96, 143, 178, 179


                                    D
  Dalgaranga crater, 65
  daubreelite, 124
  destruction by meteorites, 11, 15, 16-19, 54-7, 68-70, 73-4, 178
  diamond-bearing meteorite, 82
  direction measures, 23, 24, 86-9, 110
  distribution of meteorites, 66-68, 72, 140-3, 159
  dog and meteorite, 73
  doubters of meteorites, 154-7
  “dumbbells,” 135, 136
  “dust balls,” 106
  dust, meteoritic, 102, 116-7, 179


                                    E
  “earth-rings,” 142
  earth-trace, 92
  eating a meteorite, 82
  Einstein, A., 166
  elements in meteorites, 118-24
  elements in meteor-forming particles, 107
  elevation, apparent, 88, 90
      _see also_ altitude
  “end-point,” 16, 86-91
  Enrico Fermi Institute, 168
  Ensisheim stone, 152, 154
  Eta-Aquarid shower, 114
  etching meteorites, 119-123
  evaporation, _see_ vaporization
  “explosions” of meteors and/or meteorites, 18, 23, 25, 55, 56-60,
          63, 86, 92


                                    F
  fall, determining area of, 13-14, 24, 26
      _see also_ oval-shaped areas of fall
  falls, witnessed, 11-22, 23-34, 67, 68-72, 82, 84-95
  Farrington, O. C., 178
  farmers as meteorite finders, 28, 30, 75-6
  Fermi (Enrico) Institute, 168
  fireballs, 2, 10, 11-13, 23-5, 54, 69, 84-92, 102, 106, 149, 151
  fishermen net meteorite, 78
  fixes, 84-90
  “flanged buttons,” 135, 136
  flight-path, _see_ trajectory
  Flows meteorite, 82
  footwarmer, meteorite used as, 78
  “fossil” meteorites, 144-6
  funnels, impact and penetration, 20, 29, 32, 33, 42, 44
  Furnas County stone, 29, 31, 32-4, 128, 178
      _see also_ Norton County fall
  fusion crust, 20, 21, 130, 132, 140, 148, 172


                                    G
  Galle, J. G., 92
  gamma-ray spectroscopy, 171
  Geminid shower, 114
  Giacobinid shower, 103, 114, 115
  Giacobini-Zinner comet, 114
  glass, 138, 145
      _see also_ silica-glass; tektites
  Glorieta iron, 126
  great-circle distributions, 140-3


                                    H
  Harvard meteor-photographs, 110-1
  Haviland craters, 50, 52, 65, 66
  Hayden Planetarium, 129
  height, 88, 90, 105, 106
  Henbury craters, 50, 65
  Hey, M. H., 178
  hexahedrites, 119, 120
  Holbrook stone shower, 128
  Howard, E., 155-7
  hunting meteorites, methods of, 84-100


                                    I
  “ices,” 106
  Illinois Gulch iron, 76
  impactites, 143-5
  India, Museum of the Geological Survey of, 41
  Indians, 41, 76, 150
  Institute for Nuclear Studies, 168
  Institute of Meteoritics, 5, 24, 26-32, 80, 84, 96, 168, 169, 171
  intersecting lines of sight, 84-90
  interstellar space, 92, 171
  irons, 19, 36, 37, 39, 40, 41, 48, 73, 75, 76, 78, 82, 99, 116,
          118, 120, 121, 128, 129, 133, 143, 150, 155, 163, 167,
          174-5, 179


                                    J
  Jones, W. B., 179
  Jupiter, 102, 142, 160, 161, 164


                                    K
  Kaalijarv crater, 65
  kamacite, 124
  Kasamatsu stone, 74
  Kayser, E., 92
  Kenton iron, 75
  Kilbourn stone, 74
  Klepesta, J., 2
  Krasnoyarsk iron, 155


                                    L
  laboratory procedures, 5, 81, 83, 118, 120, 128, 167-71
  La Caille meteorite, 78
  L’Aigle stone shower, 157, 158
  Lake Murray iron, 77, 79, 80-3
  Lake Okeechobee stone, 78
  LaPaz, L., 178, 179
  largest meteorites, _see_ weights and weighing of meteorites
  Leningrad (St. Petersburg), Academy of Science of, 158
  Leonard, F. C., 178
  Leonid shower, 114, 115
  Lick Creek iron, 76
  Londonderry Laboratory for Radiochemistry, 168
  Los Alamos Scientific Laboratory, 171
  “lost” meteorites, 38, 40, 41, 80, 82, 95
  lunar craters, 60-4, 179
      _see also_ moon, craters on
  Lyrid shower, 112, 114


                                    M
  magic attributed to meteorites, _see_ superstitions
  Mars, 160, 161
  “Martian spaceship,” 60
  Maximilian I, 152-4
  Mazapil iron, 116
  Mebane, A. D., 177
  Medvedev, P. I., 10
  Merrill, G. P., 178
  Mesaverde iron, 76
  metals, meteorites as sources of, 174-5
  meteorite detectors, 48, 52, 96-100, 178
  meteoriteless meteorite crater, 56
  meteorite-planet hypothesis, 140, 160, 163, 174
  meteorite showers, 73-4, 128, 157, 158, 159
  meteorites, true or false, 130-3
  meteoritics, 5, 104, 166-7
  meteors, 101-17
  meteor showers, 103, 111, 112-116, 117, 152, 153
  meteor steel, 167
  micro-meteorites, _see_ dust, meteoritic
  minerals in meteorites, 120-6, 156, 163
  miners as meteorite finders, 70, 76, 144
  mining in space, 162, 174-6
  Montezuma temple iron, 76
  moon, 60-4, 140, 170
  moon, craters on, 60-4, 179
  Morito iron, 128
  Moscow, Academy of Sciences at, 20
  Mount Darwin, Tasmania, crater, 65;
      silica-glass, 143
  Mount Joy iron, 75-6
  Murfreesboro iron, 76


                                    N
  “natural nuclear explosion,” 60
  Neumann, J., 158
  nickel-iron, 19, 32, 96, 98, 118, 120, 122, 123, 124, 126, 132,
          143, 150, 161, 163, 170, 174
  Norton County fall, 23-34, 90, 93, 94, 96, 126, 128, 130, 168
  Novo-Urei stone, 82


                                    O
  obsidian mistaken for tektite, 138-9
  octahedrites, 120, 121
  Odessa crater, 43, 44, 52, 65, 66, 75
  oldest collection of meteorites, 76
  oldest crater, 52
  Olivier, C. P., 116, 177
  Opava irons, 76
  orbits, 108-112, 160, 161
  origin of meteorites, 160, 163, 164, 174
  Orionid shower, 112, 114
  oval-shaped areas of fall, 32, 89, 94, 159
  ownership of meteorites, 36, 38


                                    P
  Pallas, P. S., 155
  pallasites, 122, 155
  Pantar stone shower, 74
  parallax and parallactic displacement, 105, 106
  Paris, Museum of Natural History at, 38, 158
  paths of meteors, 84-94, 116
      _see also_ earth-trace; orbits; speeds; trajectory; velocity
  patterns, structural, 120, 121, 172
  Pawnee Indians, 41
  Peary, R. E., 36, 37, 128
  Perry, S. H., 179
  Perseid shower, 114, 115
  person struck by meteorite, 70-2, 178, 179
  piezoglyphs, 131, 132
  Pittsburgh iron, 78, 80
  plessite, 124
  plotting meteor paths, 116
  Plymouth meteorite, 75
  Podkamennaya Tunguska fall, 50, 54-60, 65, 102
  polishing meteorites, 5, 118, 120, 123
  Port Orford stony-iron, 40
  Prague Observatory, 2
  Prior, G. T., 178
  Proctor, R. A., 164
  Pultusk fireball, 92
  Purdue University, 170
  pure science, 166
  “purloined” meteorite, 36, 39


                                    Q
  Quadrantid shower, 114


                                    R
  radiant of meteor shower, 112, 113
  radioactivities, 5, 60, 133, 138, 168, 170-1
  Rafrüti iron, 78
  rainfall, connected with meteor
  showers, 117
  random distribution, 62
  ray-craters, 60-4
  recoveries of meteorites, 14-22, 24, 26-8, 31, 33, 35, 75-82,
          84-100
  Red River iron, 41
  re-entry, 172, 173
  reports, eyewitness, 23, 24, 84, 86, 90, 92, 94-5
  reversed matter, 56, 58-60
  Richland iron, 75
  Rigel, 92
  rocketry, 110, 174-6
  Rojansky, V., 58


                                    S
  sacred meteorites, 147-50
      _see also_ superstitions
  San Emigdio stone, 80
  satellites, man-made, 172
  Saturn’s rings, 142
  sawing meteorites, 81, 167-9
  Schiaparelli, G. V., 177
  Schmidt, J. F. J., 149
  schreibersite, 124
  Scottsville iron, 76
  Seeläsgen iron, 75
  Shakespeare, meteors mentioned by, 152
  shale balls, 48, 133
  shapes of meteorites, 18, 32, 126-8, 134-7, 140, 172
  Shirihagi iron, 150
  “shooting stars,” 104
  showers, meteor, 103, 111, 112-116, 117, 152, 153
  showers, meteorite, 73, 74, 128, 157, 158, 159
  Siena fall, 156
  Sikhote-Alin fall, see Ussuri
  silica-glass, 50, 54, 143
      _see also_ glass; tektites
  silicate-siderites, 122, 123
  Sirius, 92
  “skymarks,” 92
  smallest meteorites, 48, 128
      _see also_ dust, meteoritic
  Solar System, 5, 111, 164, 175-6
  sounds made by falling meteorites, 11, 12, 24, 25,26, 94-5, 148,
          159
  space exploration and ships, 5, 168, 170-6
  space-probes, 170-1
  space mining, 162, 174-6
  spectra and spectrograms, meteor, 107
  spectroscopy, gamma-ray, 171
  speeds, 21, 32, 107, 108, 109, 110-12, 126, 172
  Spencer, L. J., 179
  stainless steel, 120, 122, 167
  stones, meteoritic, 28-34, 35, 70, 71-2, 73-4, 78, 80, 82, 118,
          120-4, 128, 130, 131, 132, 133, 148, 156-7, 163
  stony-irons, 40-1, 118, 122, 124, 163
  strata, effect of impact on, 43, 44-5, 48-51
  superstitions about meteors and meteorites, 25, 56, 82, 134, 136,
          147-52, 154
  swarms, meteorite, 50
  swarms, meteor-particle, 111, 112, 114
  Swindel, G. W., Jr., 179
  “swords from heaven,” 150
  Sylacauga stone, 71-2, 74, 179


                                    T
  taenite, 124
  tektite-obsidian test, 138-9
  tektites, 134-146, 160
  tests for true meteorites, 130-3
  “thumb-prints,” 131, 132
  trajectory, 90, 92, 173
  tritium, 170
  Tucson iron, 128
  Tungus, _see_ Podkamennaya Tunguska
  twice-found meteorites, 76
  Tycho, lunar ray-crater, 61


                                    U
  University of California Radiation Laboratory, 58
  University of Chicago, 168
  University of New Mexico, 24, 30
      _see also_ Institute of Meteoritics
  University of Nebraska, 30, 80
  U. S. National Museum, 40, 158
  Ussuri fall, 10, 11-34, 42, 50, 54, 65, 130


                                    V
  vaporization, 102, 107, 116, 126, 128, 143, 145, 162, 172, 174
  velocity, 107, 108, 109, 171, 179
  Venus, 102, 162
  Verbeek, R. D. M., 140
  Vienna, National History Museum of, 41, 158
  volcanic theories, 138, 155, 156, 164


                                    W
  Wabar craters, 50, 65, 143, 162
  Wasiutynski, J., 63-4, 179
  water, meteorites under, 78
  waves, air and water, 12, 54-5
  weather, effect of meteoritic dust on, 117
  weathering of meteorites, 38, 48, 52, 53, 54, 66, 133, 144
  weights and weighing of meteorites, 35, 36, 128, 130
  White, C. S., 179
  Widmanstätten pattern, 120, 121, 122, 158
  Whipple, F. L., 177, 179
  Willamette iron, 36, 128, 129
  Wold Cottage meteorite, 156
  Wolf Creek crater, 52, 53, 65, 75, 133


                                    Y
  Yale University, 41
  young people and meteoritics, 23, 24, 28, 34, 39, 90, 98, 99, 116
      _see also_ reports, eyewitness


                                    Z
  Zhovtnevy Hutor fall, 82




                               FOOTNOTES


[1]Also called _aerolites_.

[2]The meteorites from this crater-producing fall have been found in
    both Haviland and Brenham Townships, Kiowa County, Kansas. Either of
    these names may therefore appear in the literature.

[3]The meteorites from this crater-producing fall have been found in
    both Haviland and Brenham Townships, Kiowa County, Kansas. Either of
    these names may therefore appear in the literature.

[4]453.59 grams = 1 pound.

[5]A questionnaire for making an adequate report is obtainable by
    request from the Institute of Meteoritics, The University of New
    Mexico, Albuquerque.

[6]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 Society. Members must be at
    least 18 years old, but applicants between 14 and 18 can become
    probational members. For details write to Dr. C. P. Olivier,
    President, American Meteor Society, 521 North Wynnewood Avenue,
    Narberth, Pennsylvania.

[7]Quite recently, a fourth division, the _tektites_ (discussed in the
    next chapter), has been recognized by some authorities.

[8]Discussed in Chapter 12.

[9]The Acts of the Apostles, 19:35.

[10]Also _baetyl_ and _baetulus_, from the Greek word _baitylos_, a term
    used for sacred meteorites and stones.

[11]This metallic mass was the first stony-iron meteorite to be
    identified as such. The _pallasites_, which make up an important
    subdivision of the stony-iron meteorites, were named in honor of
    Pallas.

[12]Very recently, some authorities have concluded that there must have
    been not one but several meteorite-planets.


                              Space Nomads
                Meteorites in Sky, Field, and Laboratory
                    By Lincoln LaPaz and Jean LaPaz

Meteorites are the real tokens of space! They are samples of cosmic
matter we can actually take in our hands. Science values them greatly as
specimens of _the only tangible_ substances we have from remote and
inaccessible regions of the universe.

These mysterious “space nomads” are revealing to today’s scientists many
amazing and usable facts about conditions in outer space, about the age
of our Solar System, and even about the probable constitution of our own
home planet.

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 encounter.

You will also see in SPACE NOMADS:

The awesome event a meteorite-fall can be, with its violent sound and
light effects, and its terrific impact.

The excitement and the know-how of the hunt for these cosmic missiles.

How to tell the difference between a true meteorite and a mistaken one.
Ditto, meteorite craters.

How to make your own contribution to science by knowing the right way to
observe and report meteors and meteorites.

What is inside them, and how they vary in content and structure.

The moon as a meteorite target.

The strange history of the subject—the amusing superstitions and
fantastic notions believed until recently about “shooting stars” and
“stones falling from the sky.”

And more.


Here is an easy but sound introduction to the rapidly developing science
of meteoritics. All of the information is up-to-date, much of it
firsthand, for the authors are themselves professional meteoriticists.
Daily they are engaged in fieldwork, laboratory analysis, and advanced
research at one of the world’s chief centers for this study. (See back
of jacket.)

                          A HOLIDAY HOUSE BOOK
                             12 UP    $3.95

                         _Jacket by Leo Manso_

    [Illustration:                                   HARVEY CAPLIN PHOTO
     Lincoln LaPaz]

On the moon is a ray-crater named LaPaz 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 meteorites. Lincoln LaPaz
is a leading pioneer as well as a widely recognized authority in
meteoritics, an important branch of astronomy. He was born on Lincoln’s
birthday, in Wichita, Kansas, where he grew up. Although both his
master’s degree, at Harvard, and his doctorate, at Chicago, were in
mathematics, his chief interest since boyhood has been in meteorites and
meteors. Today he is Director of the Institute of Meteoritics at the
University of New Mexico, where he also heads the Division of Astronomy.

    [Illustration:                                          RAVINI PHOTO
     Jean LaPaz]

Jean LaPaz was born in Hanover, New Hampshire. Since girlhood she has
been close to her father in his fascinating work. When she was a
high-school student in Ohio, she did some serious fieldwork as a member
of the Ohio State University Meteorite Expeditions. Later, she received
both a Bachelor of Science degree in geology and a Master of Arts in
English from the University of New Mexico. Science and Literature
continue to be her mutually favoring interests.




                          Transcriber’s Notes


—Retained publication information from the printed edition: this eBook
  is public-domain in the country of publication.

—Silently corrected a few palpable typos.

—In the text versions only, text in italics is delimited by
  _underscores_.







End of Project Gutenberg's Space Nomads, by Lincoln LaPaz and Leota Jean LaPaz