An asteroid is like a planet, but smaller. The name “asteroid” means “like a star” in the ancient Greek language. Asteroids may look like small stars in the sky, but they really do move around the Sun, while stars only seem to move because the Earth spins. Like planets, asteroids do not make their own light. Because of this, some people think “asteroids” is not a good name, and think that the name “planetoid” (“like a planet”) would be a better name.
Most asteroids are made of rock, but some are made of ice or metal. Most asteroids in our Solar System are in the asteroid belt between Mars and Jupiter.