Meteorites:
Rocks From Outer Space!
"To hold in your hand a piece of the solar system, a rock from space... this is the allure of the meteorite" O. Richard Norton
If you have ever seen a "shooting star" in the night's sky, you have already seen a rock from outer-space being pulled to the ground by the earth's gravitational forces. These rocks come from several sources in space. Some are pieces of debris from the tails of passing comets or from the asteroid belt. Others are believed to be pieces from our moon, Mars or other planets or moons. Before it hits our atmosphere, it is called a meteoriod. A meteore is the fireball that results when a meteoriod is pulled to the earth by gravitational forces. That is what you see when you see a shooting star. Most fragments are too small to survive the firey journey to the ground, but some survive and these are called meteorites.
It is interesting to learn that meteorites are classified into three categories according to their composition. "Iron Meteorites" are composed of an iron-nickel alloy. "Stony Meteorites" are made of stone as the name implies. The third group is a mixture of stone and metal. They are called "Stony-Iron Meteorites". Stony meteorites are the most common type that can be seen falling to the earth.
Meteorites have been found all over the world, but Antarctica has been the best place to collect them. For the past 20 years over 17,000 meteorite fragments have been collected there.
Meteorites have taught us that the chemical elements we find on earth are also found on other celestial bodies, but in different proportions and mixtures. If you think about it, meteorites are geological history books delivered from space. They can reveal to us the age and composition of our neighbors in the solar system and far beyond.