Oort cloud

American  

[awrt kloud, ohrt] / ˈɔrt ˌklaʊd, oʊrt /

noun

Astronomy.

1. a region of our solar system far beyond the orbit of Pluto, in which billions of comets move in nearly circular orbits unless one is pulled into a highly eccentric elliptical orbit by a passing star.

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Oort cloud Scientific  

/ ôrt /

1. A sphere-shaped mass of more than 100 billion comets that makes up the outer edge of the solar system, surrounding the Kuiper belt and the planets. Some comets from this area are drawn into the inner solar system by passing stars and other forces and take more than 200 years to make one complete orbit of the Sun.

2. Compare Kuiper belt

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Etymology

Origin of Oort cloud

First recorded in 1975–80; after Dutch astronomer Jan Hendrik Oort (1900–1992), who proposed its existence

Compare meaning

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

• Oort cloud vs. Kuiper belt

Example Sentences

And when people are ogling the night sky this week, they should also keep an eye out for two additional celestial sightings — Saturn and the appearance of an ancient Oort cloud comet, she added.

From Los Angeles Times • Oct. 16, 2024

But, the team calculated, it's slightly more likely that a rogue, Neptune-like planet from another solar system was snagged by the sun's gravity and came to rest somewhere in the Oort cloud.

From Scientific American • Jun. 28, 2023

The object originates in the Oort cloud, a collection of icy bodies at the edge of the Solar System.

From BBC • Jan. 31, 2023

Those long-period comets compose the Oort cloud, or a band of cometary debris on the fringes of the solar system.

From Washington Post • Jan. 21, 2023

As it is, even with the Hubble telescope, we can’t see even into the Oort cloud, so we don’t actually know that it is there.

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