• Asteroids are lumps of rock that orbit the Sun. They are sometimes called the minor planets.

 

• Most asteroids are in the Asteroid Belt, which lies between Mars and Jupiter.

 

• Some distant asteroids are made of ice and orbit Sun and Neptune.

 

• A few asteroids come near the Earth. These are Near Earth Objects (NEOs).

 

• The first asteroid to be discovered was Ceres in 1801. It was detected by Giuseppi Piazzi, one of the Celestial Police whose mission was to find a ‘missing ‘planet.

 

• Ceres is the biggest asteroid – 940km across, and 0.0002% the size of the Earth.

 

• The Galileo space probe took close-up pictures of the asteroids Ida and Gaspra in 1991 and 1993.

 

• There are half a million or so asteroids bigger than 1km across. More than 200 asteroids are over 100km across.

 

• The Trojan asteroids are groups of asteroids that follow the same orbit as Jupiter. Many are named after warriors in the ancient Greek tales of the Trojan wars.