FACTS about ASTEROIDS

Compiled by Chilman Sahni

Asteroids are sometimes called minor planets. They are lumps of rock orbiting the Sun, mostly in the asteroid belt between the orbits of Mars and Jupiter.

• The first and the largest asteroid, Ceres is 936km in diameter and was found on New Year’s Day 1801. Since then thousands have been found. Twelve of them are more than 250 km wide and 26 are larger than 200 km in diameter. As telescopes have improved, more and more small asteroids have been detected. There are probably about 100,000 asteroids larger than 1 km in diameter. Some experts think there may be as many as 1.2 million.

• Vesta, the fourth asteroid to be discovered (in 1807), is the only one bright enough to be seen without the telescope.

• Astronomers believe that, on average, one asteroid larger than 0.4 km strikes Earth every 50,000 years. Some 65 million years ago a 10 km diameter asteroid crashing to Earth may have been responsible for wiping out the dinosaurs. It would have caused a catastrophic explosion, affecting the climate and chemical composition of the atmosphere and destroying the plants and animals on which the dinosaurs fed. As recently seen in 1991 a small asteroid came within 170,600 km of Earth, the closest recorded near miss. On 30 January 2052 an asteroid is predicted to pass as close as 119,678 km.

• Toutatis (asteroid 4,179) was discovered in 1989. It is named after the Celtic God Toutatis, whose name is used as an oath by the comic strip character Astérix the Gaul. Toutatis measures 4.6 by 2.4 by 1.9 km.  It passes Earth every 4 years and is one of the largest space objects to come close to us. On 29 September 2004 Toutatis came within 1,555,818 km of Earth. It next visited Earth on 9 November 2008 and it came 7,524,773 km.

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