comet (komet)

[ Comet of Donati, October 3d, 1858. (From "Annals of Harvard Observatory.") extended away from the sun into a stream of light (the tail ) reaching a length of from 2° to 90°. Comets which follow a parabolic orbit appear but once, their orbit being infinite, and are called parabolic comets; those moving in ellipses return periodically, and are called periodic comets. The fact of the periodicity of some comets was first established by Halley with reference to the comet of 1682. The paths in which they move are not, like those of the plan ets, all nearly in the same plane as the orbit of the earth, but are inclined to that orbit at all angles; and their motion along their paths, though generally direct, that is, in the same direction as that of the earth and the other planets, is sometimes retrograde. Some comets have no nucleus; and this is the case with every one while it is still very remote, when it appears as a mere nebulous patch. In this state it is called a telescopic comet. As it approaches the sun, the nucleus is gradually formed as a central but not sharply defined point of light; later, the tail, consisting of vaporous matter driven back by some repellent influence of the sun, often with enormous velocity, is formed; envelops rise succe ively from the nucleus, each extend and lastly, if the comet is a bright one, a series of bright ing back into the tail, and gradually disappearing. The matter of which comets are composed is so transparent slightest diminution of their luster. Of their physical con that the faintest stars are seen through them without the stitution little is definitely known. The most remarkable discovery of recent times regarding them is the identity of the course of some of them with the orbit of certain showers of shooting stars. This was first demonstrated by the Italian astronomer Schiaparelli, who proved the agreement between the orbit of the great comet of 1862 and that of the star-shower seen annually about August 1st-10th. Very remarkable comets appeared in 1456, 1680, 1811, 1841, 1858 (Donati's), 1861, and 1874. They have always been objects of superstitious fear. See cut under envelop. (Euen night by night) on that prodigious Blaze, That hairy Comet , that long streaming Star, Which threatens Earth with Famine, Plague, and War? Sylvester, tr. of Du Bartas's Weeks, i. 2. 2. In her., same as blazing - star.-3. One of a group of humming-birds with long forked tails: as, the Sappho comet, Cometes sappho; the Phaon comet, Cometes phaon.-4t. A game of cards, somewhat like speculation, invented and popular in the reign of Louis XV. of France. What say you to a poule at comet at my house? South erne. Comet wine, wine made in any of the years in which notable comets have been seen, and supposed in consequence to have a superior flavor. The old gentleman yet nurses some few bottles of the famous comet year (i. e. 1811), emphatically called comet wine . London Times . cometarium (kom-e-tā'ri-um), n.; pl. comet a ria (-a). [NL., neut. of come tar i us : see come tary .] An astronomical instrument intended to represent the movement of a comet in that part of its orbit which is near the sun. cometary (kom'e-tā-ri), a . and n . [ = F. comé taire = Sp. Pg. It. cometario , come tar i us , comet a , a comet: see comet .] I. a. Of or a telescope of low power, but with a wide field, used to search for comets. Also called comet seeker. cometic (ko-met'ik), a. [ ments. Others [nebulæ] of the cometic shape, with a seeming nucleus in the centre, or like cloudy stars surrounded with a nebulous atmosphere. A. M. Clerke , Astron. in 19th Cent., p. 28.