Oort cloud


: a spherical shell of cometary bodies believed to surround the sun far beyond the orbits of the outermost planets and from which some are dislodged when perturbed to fall toward the sun compare kuiper belt

Examples of Oort cloud in a Sentence

Recent Examples on the Web The inner edge of the Oort cloud is somewhere between 2,000 and 5,000 thousand Astronomical Units (AU, the length of the typical Earth-Sun distance) away. Paul Sutter, Ars Technica, 10 July 2023 The solar system includes the distant Oort cloud, a spherical collection of cometlike bodies bound by the sun's gravity that may stretch halfway to the closest star. Tim Folger, Scientific American, 18 June 2022 The colossal comet may be dashing our way from the Oort cloud at a speedy 22,000 miles per hour, per Space.com. Elizabeth Gamillo, Smithsonian Magazine, 15 Apr. 2022 The Oort cloud represents the very edges of our solar system. Joshua Rapp Learn, Discover Magazine, 23 July 2021 The Oort cloud is even further than the Kuiper belt, a region where NASA has discovered the mysterious Arrokoth. Chris Ciaccia, Fox News, 1 Sep. 2020

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'Oort cloud.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Jan Oort †1992 Dutch astronomer

First Known Use

1974, in the meaning defined above

Time Traveler
The first known use of Oort cloud was in 1974

Dictionary Entries Near Oort cloud

Cite this Entry

“Oort cloud.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Oort%20cloud. Accessed 24 Jun. 2024.

Kids Definition

Oort cloud

: a spherical shell of small icy bodies (as comets) that orbit the sun far beyond Pluto

named after Jan Oort, 1900–1992, Dutch astronomer

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