Outer Solar System Asteroids

The outer solar system, beyond the orbit of Jupiter, is awash in asteroids, most of which are icy compared with the rocky and metallic bodies of the inner solar system. In addition to the Trojans around Jupiter, a group of about 13,000 asteroids with highly eccentric and inclined orbits cross the path of Jupiter, in positions that cause relatively frequent collisions and deflections of the asteroids into the inner solar system. Asteroids whose orbits are inside the orbit of a planet generally do not hit that planet, but only hit planets closer to the Sun than its orbit. This is an artifact of the great gravitational attraction of the Sun, constantly pulling these objects closer in toward the center of the solar system.

Centaurs, a group of asteroids with highly eccentric orbits that extend beyond yet cross the orbits of Jupiter and saturn, can thus potentially collide with these planets. Many of these are large bodies thought to have been deflected inward from the Kui-per belt, into unstable orbits that have them on an eventual collision course with the giant planets, or to be flung into the inner solar system. Coming from so far out in the solar system, Centaurs are icy bodies. one Centaur, Chiron, is about 50 miles (85 km) in diameter, is classified as a minor planet, and exhibits a cometary tail when at its perihelion but not along other parts of its orbit. Chiron therefore is classified as both an asteroid and a comet.

Trans-Neptunian objects are a class of asteroid that orbit beyond the orbit of Neptune at 30 A.u., and beyond into the Kuiper belt, extending from 30 to 49 A.u. Beyond the Kuiper belt is a gap of about 11 A.u. containing relatively few asteroids before the beginning of the oort Cloud. The total number of objects in this belt is unknown but undoubtedly large, because many are being discovered as the ability to detect objects at this distance increases. More than a thousand Trans-Neptunian objects are currently documented.

Continue reading here: Kuiper Belt

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