Asteroids Monday Thanks to two summer blockbuster movies about giant rocks from outer space slamming into earth, there's been a lot of attention focused on asteroids. Believe it or not, material from outer space is bombarding the earth's atmosphere all the time.
Asteroids are smaller than planets, and are sometimes called planetoids.
The smallest are only a few thousand feet in diameter, but one of the largest, Ceres, is 620 miles across. Asteroids are part of the debris left over when the Sun and its planets were formed, fragments that never got it together enough to form another planet or moon. The asteroid belt forms a band that orbits the sun in the gap between Mars and Jupiter. Sometimes asteroids ram into each other in the belt, creating meteors that shoot off from the orbit of the belt and start their own course, which can coincide with the Earth's own orbit. Tuesday It's easy to get comets, meteors and asteroids confused.