1. A ring of small astronomical objects orbiting through the outer solar system, beyond the farthest planets, Neptune and Pluto.

It is believed that the Kuiper belt is a source of comets.

2. A disk-shaped swarm of 200 million comets and comet fragments located from just beyond the orbit of Neptune and extending past Pluto.

Named after Gerard Peter Kuiper (1905-1973), a Dutch-born U.S. astronomer who made extensive studies of the solar system. His discoveries included the atmosphere of the planet Mars and that of Titan, the largest moon of the planet Saturn.

His spectroscopic studies of Uranus and Neptune led to the discovery of features subsequently named "Kuiper bands", which indicate the presence of methane.

He was an adviser to many NASA exploratory missions, and pioneered the use of telescopes on high-flying aircraft.