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Comets - School Essays

Comets

A comet is generally considered to consist of a small, sharp nucleus
embedded in a nebulous disk called the coma. American astronomer Fred L. Whipple
proposed in 1949 that the nucleus, containing practically all the mass of the
comet, is a “dirty snowball” conglomerate of ices and dust. Major proofs of the
snowball theory rest on various data. For one, of the observed gases and
meteoric particles that are ejected to provide the coma and tails of comets,
most of the gases are fragmentary molecules, or radicals, of the most common
elements in space: hydrogen, carbon, nitrogen, and oxygen. The radicals, for
example, of CH, NH, and OH may be broken away from the stable molecules CH4
(methane), ...

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fade very slowly with time, as
would be expected of the kind of structure proposed by Whipple. Finally, the
existence of comet groups shows that cometary nuclei are fairly solid units. The
head of a comet, including the hazy coma, may exceed the planet Jupiter in size.
The solid portion of most comets, however, is equivalent to only a few cubic
kilometers. The dust-blackened nucleus of Halley's comet, for example, is about
15 by 4 km (about 9 by 2.5 mi) in size. ...

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Comets. (2005, February 25). Retrieved July 12, 2025, from http://www.essayworld.com/essays/Comets/22809

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"Comets." Essayworld.com. February 25, 2005. Accessed July 12, 2025. http://www.essayworld.com/essays/Comets/22809.

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PAPER DETAILS

Added: 2/25/2005 07:07:38 AM
Category: Science & Nature
Type: Free Paper
Words: 275
Pages: 1

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