Changes

The word "comet" first appears in [[Aristotle]]'s ''Meteorology,'' and derives from the Greek ''komē,'' hair.<ref>[http://classics.mit.edu/Aristotle/meteorology.1.i.html Meteorology, part 1], translation by E. W. Webster. See part 7: "The kind of comet varies according to the shape which the exhalation happens to take. If it is diffused equally on every side the star is said to be fringed, if it stretches out in one direction it is called bearded. We have seen that when a fiery principle of this kind moves we seem to have a shooting-star: similarly when it stands still we seem to have a star standing still." Aristotle believed comets could be formed ''from'' stars: "But when the exhalation is constituted by one of the fixed stars or the planets, owing to their motion, one of them becomes a comet. The fringe is not close to the stars themselves."</ref>

The word "comet" first appears in [[Aristotle]]'s ''Meteorology,'' and derives from the Greek ''komē,'' hair.<ref>[http://classics.mit.edu/Aristotle/meteorology.1.i.html Meteorology, part 1], translation by E. W. Webster. See part 7: "The kind of comet varies according to the shape which the exhalation happens to take. If it is diffused equally on every side the star is said to be fringed, if it stretches out in one direction it is called bearded. We have seen that when a fiery principle of this kind moves we seem to have a shooting-star: similarly when it stands still we seem to have a star standing still." Aristotle believed comets could be formed ''from'' stars: "But when the exhalation is constituted by one of the fixed stars or the planets, owing to their motion, one of them becomes a comet. The fringe is not close to the stars themselves."</ref>

Comet [[orbit]]s around the sun may be highly [[elliptical]], rather than nearly circular (such as planets), which takes them out past the orbit of [[Pluto]].  Some of the mass of the comet will [[sublimate]] with each pass by the sun and after many passes the comet may no longer be active and be simply an [[asteroid]].

Comet [[orbit]]s around the sun may be highly [[ellipse|elliptical]], rather than nearly circular (such as planets), which takes them out past the orbit of [[Pluto]].  Some of the mass of the comet will [[sublimate]] with each pass by the sun and after many passes the comet may no longer be active and be simply an [[asteroid]].

[[Image:Halley1910a.jpg|right|thumb|300px|Halley's Comet on its 1910 appearance. This Yerkes Observatory photograph is highly enlarged; the comet would not have appeared this large or bright to the naked eye.]]

[[Image:Halley1910a.jpg|right|thumb|300px|Halley's Comet on its 1910 appearance. This Yerkes Observatory photograph is highly enlarged; the comet would not have appeared this large or bright to the naked eye.]]