- 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.
Every 50 million years, the Earth is hit by an asteroid measuring over 10km across.
Asteroids Based More Information Through Powerpoint Presentation & PDF