The first asteroids, or minor planets, were discovered in the very early 1800s. Eventually over 4,000 of them were found. Astronomers had calculated that another planet should lie between Mars and Jupiter, and the asteroid belt seemed to solve this problem. Asteroids are composed of raw material from the creation of our solar system. For some reason, this material did not come together to form one planet.
Asteroids are the source of most meteors that have hit the Earth.
Jupiter is named after the king of the Roman gods. It is the largest planet, yet it spins very quickly on its axis- one day is about 10 Earth hours. The atmosphere is composed mainly of hydrogen and helium, although it is the small amounts of gases like ammonia and methane which make the bands on Jupiter look so colorful. It is very turbulent in the atmosphere, with huge storms frequently lasting years. Jupiter is a gas giant with a very faint ring system.