"Asteroids" redirects here. This article is about the astronomical bodies. For the arcade game, see Asteroids (game).

An asteroid is a predominantly rocky body that orbits around its star. In our solar system, asteroids are the best known class of minor planet (or planetoid). They are much smaller than even the small major planets such as Mercury or Mars. The vast majority of the asteroids are found within the main asteroid belt, with elliptical orbits between those of Mars and Jupiter. It is thought that asteroids are remnants of the protoplanetary disc, and in this region the incorporation of protoplanetary remnants into the planets was prevented by large gravitational perturbations induced by Jupiter during the formative period of the solar system. Some asteroids have moons.

Asteroids in the solar system

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Hundreds of thousands of asteroids have been discovered within the solar system and the present rate of discovery is about 5000 per month. As of April 14, 2006, from a total of 330,795 registered minor planets, 129,436 have orbits known well enough to be given permanent official numbers. Of these, 13,040 have official names (trivia: at least 610 of these names require diacritics). The lowest-numbered but unnamed minor planet is (3360) 1981 VA; the highest-numbered named minor planet is 129342 Épendes .

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NPR Topics: Space

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