An asteroid is a bit of rock. Most of the asteroids in our solar system can be found orbiting the Sun between the orbits of Mars and Jupiter. Think about the asteroids as cars on the highway. Sometimes, the asteroid cars run into one another. When this happens, the asteroids may break up into smaller asteroids.
Scientists think that most asteroids are the result of collisions between larger rocky space bodies.
Asteroids can be a few feet to several hundred miles wide. The belt probably contains at least 40,000 asteroids that are more than 0.5 miles across. If an asteroid is captured by the gravitational pull of a planet, the asteroid can be pulled out of the belt and go into orbit as a moon around the planet that pulled on it. Show me the Level 2 version of this page. Show me a printable version of this page.