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Essay Archive - Comets
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 m....
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