Kuiper belt

American  

[kahy-per belt] / ˈkaɪ pər ˌbɛlt /

noun

Astronomy.

1. a disk-shaped region on the edge of the solar system that contains masses of ice and icy rock, believed to be the source of comets with orbital periods of less than 200 years.

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Kuiper belt British  

/ ˈkaɪpə /

noun

1. 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 See also Oort

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Kuiper belt Scientific  

/ kī′pər /

1. A disk-shaped region in the outer solar system lying beyond the orbit of Neptune and extending to a distance of about 50 astronomical units, 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.

2. ◆ The bodies populating this region are known as Kuiper belt objects, and unlike the bodies in the Oort cloud they are believed to have originated in situ. There are an estimated 70,000 such objects having diameters of more than 100 km (62 mi). The dwarf planet Pluto and its moons are also found in this region.

3. Compare Oort cloud

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Etymology

Origin of Kuiper belt

First recorded in 1985–90; named after G. P. Kuiper, who proposed its existence

Compare meaning

How does kuiper-belt compare to similar and commonly confused words? Explore the most common comparisons:

• Oort cloud vs. Kuiper belt

Example Sentences

After billions of years, two major planetesimal belts remain: the asteroid belt between Mars and Jupiter and the Kuiper belt beyond the giant planets.

From Science Daily • Dec. 6, 2025

Around our sun, these include the inner planets -- Mercury, Venus, Earth and Mars -- the asteroid belt and the Kuiper belt objects such as Pluto.

From Science Daily • Mar. 22, 2024

Beyond Neptune’s orbit lie thousands of small icy objects in the Kuiper belt, with Pluto its most famous resident.

From Science Magazine • Oct. 3, 2023

The inner ring is analogous to our asteroid belt, while the outer ring is comparable to the sun’s Kuiper belt.

From New York Times • May 8, 2023

The Kuiper belt was actually theorized by an astronomer named F. C. Leonard in 1930, but the name honors Gerard Kuiper, a Dutch native working in America, who expanded the idea.

From "A Short History of Nearly Everything" by Bill Bryson