An asteroid is a small planet that revolves around the sun. The largest asteroid is only about 600 miles in diameter.
The asteroid belt is a region of the solar system between orbits of the planets Mars and Jupiter. Most asteroids are found in the asteroid belt.
The total mass of all the asteroids is less than that of the Moon.
11 comets and asteroids have been explored by spacecraft so far. See Nine Planets for details.
Astronomers have studied the asteroids Toutatis and Geographos using Earth-based radar observations during close approaches to the Earth.
Scientists generated computer models of the asteroid Castalia using date acquired from radar/radio telescopes.
The asteroid Vesta was observed by the Hubble Space Telescope.
On the asteroid Vesta, there is a set of three craters known as the “snowman.” They can be seen at the top left of the photo to the right. →
For more information about asteroids, visit Galileo to Jupiter. It contains information on the Galileo spacecraft, the first spacecraft to encounter an asteroid and to photograph an asteroid’s moon. It flew past Gaspra in October 1991 and Ida in August 1993. During these encounters, high resolution images were obtained.
Artist’s concept of a narrow asteroid belt
Did you know...
Those birds you see riding on the backs of zebras? They’re oxpeckers and they free their striped companions of lice, ticks and other annoyances. They also serve as a kind of body guard by flying and screaming when predators approach.