Oort cloud

(ôrt)

a moving mass of icy cosmic debris thought to exist in the vast region beyond Pluto and to be the source of the comets that orbit the sun

Origin: after J. Oort (1900-92), Du astronomer

See Oort cloud in American Heritage Dictionary 4

noun

A swarm of comets orbiting the sun at a distance of one to two light-years, proposed as a source of comets that pass near the sun.

Origin:

Origin: After Jan Hendrix Oort (1900-1992), Dutch astronomer

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Oort cloud science

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