from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A celestial body, observed only in that part of its orbit that is relatively close to the sun, having a head consisting of a solid nucleus surrounded by a nebulous coma up to 2.4 million kilometers (1.5 million miles) in diameter and an elongated curved vapor tail arising from the coma when sufficiently close to the sun. Comets are thought to consist chiefly of ammonia, methane, carbon dioxide, and water.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A celestial body consisting mainly of ice, dust and gas in a (usually very eccentric) orbit around the Sun and having a "tail" of matter blown back from it by the solar wind as it approaches the Sun.
- n. A celestial phenomenon with the appearance given by the orbiting celestial body.
from the GNU version of the Collaborative International Dictionary of English
- n. A member of the solar system which usually moves in an elongated orbit, approaching very near to the sun in its perihelion, and receding to a very great distance from it at its aphelion. A comet commonly consists of three parts: the nucleus, the envelope, or coma, and the tail; but one or more of these parts is frequently wanting. See Illustration in Appendix.
from The Century Dictionary and Cyclopedia
- n. One of a class of celestial bodies which move about the sun in greatly elongated orbits, usually elliptical or parabolic.
- n. In heraldry, same as blazing-star.
- n. One of a group of humming-birds with long forked tails: as, the Sappho comet, Cometes sappho; the Phaon comet, Cometes phaon.
- n. A game of cards, somewhat like speculation, invented and popular in the reign of Louis XV. of France.
- n. In photography, a comet-shaped defect appearing on gelatin dry plates.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. (astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit
With a little imagination, they might look like the heads of mourning women with long, streaming hair -- and in fact, the word comet comes from the Greek word for "hair."
A comet is a relatively small extraterrestrialbody witha nucleus of rock, ice, dust and gases.
No matter how many times you rewind the clock, the comet is still going to hit.
The tenuous material surrounding a comet is pushed away from the sun by radiation pressure and solar wind.
The tail of a comet is formed directly opposite the comet's path to or from the Sun.
The comet is not going to be terribly bright (in part because it has broken up into numerous fragments instead of being a single, whole comet), about magnitude 4, and has just passed through the bottom part of the constellation Lyra (right past Messier 57, the Ring Nebula; see the picture below).
"Because these particles have come from inside a comet we know that essentially the particles haven't been heated since they became part of the comet, because the comet is made of ice," he told the BBC News website.
Me: That's a smart idea because once the real comet is gone it won't be back for another 4,000 years.
Astronomers have supposed, that if a certain comet, whose path intersected the ecliptick, had met the earth in some (I forget what) sign, it would have whirled us along with it, in it's excentrick course, into God knows what regions of heat and cold.
According to SKY & TELESCOPE magazine, the comet is now bright enough to be seen with the unaided eye from very dark sites free of any light pollution.
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