Oort cloud

[ awrt kloud, ohrt ]

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.

Oort cloud

/ 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

Word History and Origins

Origin of Oort cloud¹

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

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

And what, you ask, is the Oort Cloud?

From Los Angeles Times

The Oort Cloud, a hypothesized shell of icy worlds at an unfathomable distance from the sun, has never been directly seen—and VRO won’t change that.

From National Geographic

The theory’s greatest “local” hopes, then, might be found in far-distant regions of the solar system such as in the Oort cloud, a vast assemblage of long-period comets extending out perhaps a light-year from the sun, where our star’s gravitational grip is most tenuous.

From Scientific American

They found that there is a possibility that one or more planet-size bodies came to rest in the Oort cloud, a vast collection of icy objects stretching between a few hundred billion to several trillion miles from the sun, according to NASA.

From Scientific American