Evening star., 1937-07-06
STARS, MEN AND ATOMS
Notebook of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

When 4 gigantic meteor hits the earth
what happens to it?
This question was tentatively answered
before the American Association for
the Advancement OF Science last week
by Drs. John D. Boon and Claude C.
Albritton, jr., Of Southern Methodist
University. They made a special study
Of the famous meteor crater in Arizona.
In the past it has been assumed that
under this crater, possibly at a great
depth, there was an enormous chunk of
iron which fell from the skies in the
relatively recent past-slthough possibly
before North America was inhabited.
All efforts to find this iron have failed.
There have been several efforts, due
partly to the fact that it might be ex-
pected to contain diamonds. The enor-
nous heating and sudden cooling OF 4
shooting star" furnish exactly the right
conditions for the formation OF these
gems.
The Texas geologist also stressed that
while it may logically be assumed that
the earth has been bombarded with
meteors since the beginning of its history.
no really ancient ones ever have been
found. The reason is, they believe that
shooting star big enough to reach
the earth's surface would be smashed to
bits by the explosion following the i'm
pact. II made of iron these fragments
would be destroyed by rust. If of stone,
the fine pebbles resulting would probably
be indistinguishable.
As for the Arizona meteorite, they
said, consideration of the physics in
.volved makes 1t highly improbable that
even = considerable fragment OF 1t ever
will be found. Such a body weighing
thousands Of tons, they pointed out,
might hit the surface of the earth at
speed Of so miles a second.
Studies Of high speed projectiles dur
ing the World War, DR.. Boon said,
showed that II bullet is moving at q
speed slightly greater than q half mile
a second it explodes when it strikes q
target. 1t is shattered to bits regard
less Of the angle at which 1t strikes q
resisting object. Hence, he reasoned,
certainly meteorite travelling at a rate
of 40 miles q second would explode when
it strikes the earth. Such craters as
the spectacular Arizona crater resemble
nothing more than giant shell holes.
With this thought in mind we can realize
why magnetic surveys and bore holes
have failed to locate q large meteorite
beneath meteor crater. The crater
forming meteorites were simply exploded,
backfired and shattered to bits when
they struck. Little wonder that some
OF these fragments have been found as
far as six miles away.
Evidently when giant meteorite hits
it penetrates the earth for q short dis
tance, like an air gun bullet penetrating
piece of cheese. Then it explodes.
BY the time the projectile has been
brought to a standstill it will have lost
all its energy of motion. This energy
will have been transformed and stored
in thin zone of highly compressed ma
terial which has been driven down in
front Of the projectile's nose. 1t is
possible to show that this compacted
material will be momentarily subjected
to pressures of several tens OF millions
OF atmospheres. A moment later this
material will expand, and with explosive
violence. On the surface we see the
results Of this explosion in shattered
rocks and piles OF elected materials that
rim the craters.
But not all the effects are super