The Kuiper Belt

The Kuiper Belt
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The Kuiper belt is a region beyond the planet Neptune in which at least 70,000 small, icy, slow-moving objects orbit. These relatively dark objects, "trans-Neptunians," are perhaps from 6-30 miles (10-50 km) in diameter. This belt is located from roughly 30 to over 50 A.U.'s from the Sun.
It is a region where the planet-building process was stopped in before any large objects were formed; there are only primitive remnants from the early accretion disk of the solar system, 4.5 billion years ago.

Pluto and Charon (Pluto's moon) may be extremely large members of the Kuiper belt. Another large KBO (Kuiper Belt Object) is Quaoar.

Comets and the Kuiper Belt
The Kuiper belt may be the reservoir of the short-period comets (like Halley's comet). Short-period comets orbit the sun in less than 200 years.

The Kuiper belt objects may be redirected into an eccentric orbit that comes quite close to Sun. Occasionally, one of the icy objects in the Kuiper belt is disturbed by the gravitational forces of one of the gas giant planets, causing it to approach Neptune, which sometimes propels the small object into a new, very elliptical solar orbit, where it may eventually approach the Sun (and near the Sun, the characteristic comet tail is visible).
The Discovery of the Kuiper Belt
The Kuiper belt was discovered in 1992. The Kuiper belt was named for the Dutch-American astronomer Gerard P. Kuiper, who predicted its existence in 1951.