2. A rocky object, smaller than a planet, that orbits the sun.
2. A small, irregularly shaped object made of metal; such as, iron and nickel, rocky materials, or a combination of the two that orbits the sun or a planet.
In our solar system, most of the asteroids orbit in a broad band between the orbits of Mars and Jupiter. The largest is Ceres, which is about 600 miles or 900 kilometers in diameter.
The asteroid belt is between 2 and 3.5 astronomical units (AU) from the sun, between the orbits of Mars and Jupiter.