Ring of small, icy bodies orbiting the Sun beyond the outermost planet. The Kuiper belt, named after Dutch-born US astronomer Gerard Kuiper, who proposed its existence in 1951, is thought to be the source of comets that orbit the Sun with periods of less than 200 years. The first member of the Kuiper belt was seen in 1992. In 1995 the first comet-sized objects were discovered; previously the only objects found had diameters of at least 100 km/62 mi (comets generally have diameters of less than 10 km/6.2 mi). An object originally named Xena, but now called Eris, discovered in 2003, is larger than Pluto; debate following its discovery led to the new category of dwarf planet being defined, to which both Eris and Pluto were assigned. Over a thousand members of the Kuiper belt are now known, and there are probably hundreds of thousands of bodies over 100 km/60 mi in diameter, and many millions of smaller objects.
Comets and the Kuiper Belt
(outer asteroid belt) Broadly planar zone, stretching from the orbit of Neptune at 30 AU out to about 1000 AU, populated by a substantial...
Large, distant body of the solar system, revolving around the Sun well beyond the orbits of Neptune and Pluto. Found in telescopic images in 2005,
Largest of the three known dwarf planets, orbiting beyond Neptune. Eris was discovered in 2005. It belongs to the disc of small bodies beyond Neptune