Meteorites
Imagine that while you’re on a peaceful Sunday afternoon stroll with
your
family, a large dark gray ball comes out of nowhere, just missing the
head of
your small child, shakes the earth, and produces a large crater in
the ground a
few feet ahead of you. This ball wasn’t from the young boys
playing baseball
across the street, and it wasn’t an acorn from the tree
overhead. This ashen
ball was a meteorite falling from the sky. A meteorite
is a particle from space,
large enough to enter the earth’s atmosphere, and
potentially cause damage to
the surface of the earth, a house, or a car.
Although almost getting struck by a
meteorite while outside on a walk is a
very rare occurrence, a collision with a
meteorite can be fatal. Scientists
have never encountered a fatality due to a
meteorite, but several
deformations in the surface of the earth have been linked
to meteorite
collisions. A meteorite comes from an asteroid or is a chip off of
a moon or
other planet. Many times a planet or other solar object is heated
beyond
capacity and, consequently, explodes thrusting many fragments into
the
universe. Some of these fragments are large enough to successfully enter
the
earth’s atmosphere and hit the surface at amazing speeds. Most meteorites
are
blasted apart by fire while entering the earth’s atmosphere. Meteorites
are
often dark gray or black because of their fiery descent. They are very
rough on
the outside. They are often identified by scientists by their
composition. A
meteorite has a very rare element, iridium, present in its
makeup. This makes
meteorites easy to decipher from surface rocks because all
of the earth’s
iridium sank to the core many years ago. Many meteorites are
filled with metals
that give them a rich magnetic power. Meteorites also
contain carbons. Meteorite
collision has been responsible for many craters in
the surface of the earth, and
it continues to shape the land. As for
meteorite impact becoming a threat to
civilization, it is highly unlikely.
The Torino Scale is a device used to
measure the predicted threat of a
meteorite colliding with the earth. Very few
meteorite impacts large enough
to threaten civilization are rated over zero on
the Torino Scale. This means
that it is unlikely that a very large meteorite
will strike the earth hard
enough to cause such damage. It is improbable that a
meteorite will do much
damage, and any large meteorite able to cause such damage
will probably not
enter the earth’s atmosphere in tact. The Torino Scale rates
potential
collisions from zero to ten. A "zero" rating is given to those
objects that
have the least likelihood of entering the earth’s atmosphere and
doing any
damage. A "ten" rating is given to those objects that will
certainly collide
with the earth and have the ability to cause devastating
damages. Most
objects rated one or higher usually change paths, and the rating
is changed
in time. Although it is unlikely, the next time you’re out for a
Sunday
afternoon stroll and are almost nailed by a flying ball, pick it
up.
Check it out. You may have discovered a meteorite; a rock from the
world beyond
that was, for a long time, a complete mystery to
us.
Bibliography
1. Bennett, Donahue, Schneider, Voit. The Cosmic
Perspective. Addison-Wesley
Longman, Inc. 1999. 2. www.ast1.spa.umn.edu
3. www.nasa.com 4. www.yahoo!
"Meteorites."