General Astronomy/The Kuiper Belt

The Kuiper belt is an area of the solar system extending from the orbit of Neptune (at 30 AU) to 50 AU from the Sun.

The objects within the Kuiper Belt together with the members of the scattered disk extending beyond, are collectively referred to as trans-Neptunian.

The interaction with Neptune (orbital resonance) is thought to be responsible for the apparent edge at 48 AU (a sudden drop in number of objects, see Orbit distribution below) but the current models have yet to explain this peculiar distribution in detail.


Modern computer simulations show the Kuiper belt to have been strongly influenced by Jupiter and Neptune. During the early period of the Solar System, Neptune's orbit is thought to have migrated outwards from the Sun due to interactions with minor bodies. In the process, Neptune swept up, or gravitationally ejected all the bodies closer to the Sun than about 40 AU (the inner edge of the region occupied by classical Kuiper belt objects), apart from those which fortuitously were in a 2:3 orbital resonance. These resonant bodies formed the plutinos. The present Kuiper Belt members are thought to have largely formed in situ at their present position, although a significant fraction may have originated in the vicinity of Jupiter, and been ejected by it to the far regions of the Solar system.


The first astronomers to suggest the existence of this belt were Frederick C. Leonard in 1930 and Kenneth E. Edgeworth in 1943. In 1951 Gerard Kuiper suggested that the belt was the source of short period comets (those having an orbital period of less than 200 years). The belt and the objects in it were named after Kuiper after the discovery of (15760) 1992 QB1.


An alternative name, Edgeworth-Kuiper belt is used to credit Edgeworth. The term trans-Neptunian object is recommended for objects in the belt by several scientific groups because the term is less controversial than all others — it is not a synonym though, as TNOs include all objects orbiting the Sun at the outer edge of the solar system, not just those in the Kuiper belt.


The object Pluto, formerly considered a planet, is part of the Kuiper Belt. It has an orbital inclination of 17°.