Comets
Beginning of paper
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 p ....
Middle of paper
.... clear evidence
that the escaping gases produce a jet action, propelling the nucleus of a comet
slightly away from its otherwise predictable path. In addition, short-period
comets, observed over many revolutions, tend to 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 ....
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Word count: 275
Page count: 1 (approximately 250 words per page)
