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Asteroid Ida and its moon, Dactyl
Credit: NASA

Asteroids are large rocks orbiting the Sun that are too small to be called planets.

Hundreds of thousands of asteroids have been discovered so far, about 20,000 of these have been given a name as well as a number to identify them. The largest, Pallas, is about 550 km in diameter. The smallest known asteroids are a few tens of kilometres in diameter, but we expect there to be millions more that are smaller than this.

Most asteroids are found in the Asteroid Belt, between Mars and Jupiter. Some asteroids are actually in the same orbit as Jupiter but they won’t collide with Jupiter, these are called Trojan asteroids. Other asteroids have passed very close to Earth. These are called Near-Earth Objects or NEOs.

If you stuck all the asteroids together, you would have an object that is much smaller than the Moon.


Please note that over the weekend of the 26-29th May 2017 we will be switching over to our brand new website - during this time there may be periods where the site is difficult to access, and users will be unable to request observations from the telescope. Please bear with us during this time. All should be back up and running by the 30th May 2017.