Oort cloud

The Oort cloud (sometimes called the Öpik-Oort Cloud) is a postulated spherical cloud of comets situated about 50,000 to 100,000 AU from the Sun. This is approximately 1000 times the distance from the Sun to Pluto or roughly one light year, almost a quarter of the distance from the Sun to Proxima Centauri, the star nearest the Sun.

Oort cloud objects

So far, only one potential Oort cloud object has been discovered; (90377) Sedna. With an orbit that ranges from roughly 76 to 928 AU, it is much closer than originally expected and may belong to an "inner" Oort cloud. If Sedna indeed belongs to the Oort cloud, this may mean that the Oort cloud is both denser and closer to the Sun than previously thought. This has been proposed as possible evidence that the Sun initially formed as part of a dense cluster of stars; with closer neighbors during Oort cloud formation, objects ejected by gas giants would have their orbits circularized closer to the Sun than was predicted for situations with more distant neighbors.

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Oort cloud objects

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Number

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Name

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Equatorial diameter(km)

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Perihelion (in AU)

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Aphelion (in AU)

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Date discovered

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Discoverer

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Diameter method

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90377

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Sedna

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<1800, >1180

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76 (±7)

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928

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2003

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Michael E. Brown, Chad Trujillo, David L. Rabinowitz

Related Topics:
Michael E. Brown - Chad Trujillo - David L. Rabinowitz

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thermal

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