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