Boulders in Space

Asteroids are essentially gigantic chunks of rock floating in space. They range in size from a few feet to several miles in diameter. Many asteroids orbit the Sun. Most are located in an area between the orbits of Mars and Jupiter known as the asteroid belt. There are at least 30,000 of these giant boulders in this area, each in it own individual orbit around the Sun. The asteroid belt is somewhat of a mystery. It seems there should be a planet here in this large gap instead of asteroids. Many astronomers believe that billions of years ago a large, rocky planet may have existed here. It may have been blasted apart by some type of cataclysmic event, such as a collision with a large planetoid or even another planet. Another theory states that these asteroids may have formed from the primordial material left over from the formation of the solar system. The intense gravity of Jupiter may have prevented this material from coalescing into a planet. The asteroids in the asteroid belt range in size form just a few hundred feet to several miles. The largest, Ceres, is over 630 miles in diameter. Other asteroids have highly elliptical orbits that take them very close to the Sun. Occasionally, collisions and gravitational close encounters can push asteroids out of the asteroid belt and send them careening inward towards the sun. Occasionally, some of these particles may come close enough to the Earth to get caught by its gravity. They may enter the atmosphere as meteors. If they survive the heat of entry and strike the ground, the will be referred to as meteorites. Scientists can study meteorites to learn more about the asteroids from which they originated.

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