|Kuiper belt (ˈkɪpə)|
|See also Oort cloud a region of the solar system beyond the orbit of Neptune, some 30--1000 astronomical units from the sun, containing up to one thousand million icy planetesimals or comet nuclei|
|[C20: named after G. P. Kuiper (1905--73), Dutch American astronomer, who proposed it in 1951]|
|Kuiper belt (kī'pər) Pronunciation Key
A disk-shaped region in the outer solar system lying beyond the orbit of Neptune and containing thousands of small, icy celestial bodies. It is believed to be a reservoir for short-period comets (comets that make one complete orbit of the Sun in less than 200 years). The Kuiper belt is named after American astronomer Gerard Kuiper (1905-1973), who first predicted its existence. ◇ The bodies populating this region are known as Kuiper belt objects, and unlike the bodies in the Oort cloud they are believed to have orginated in situ. There are an estimated 70,000 such objects having diameters of more than 100 km (62 mi). Pluto, which is traditionally classed with the planets, together with its moon Charon, are found in this region and are thought by some astronomers to be large Kuiper belt objects. Compare Oort cloud.