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Comet

com-et (kom'it) n. Astron. Astron. A celestial body, observed only in the 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 or 1.5 million miles in diameter, an elongated curved vapor tail arising from the coma when sufficiently close to the sun, and thought to consist chiefly of ammonia, methane, carbon dioxide, and water.

me-te-or(me/te-er) n.  1. The luminous trail or streak that appears in the sky when a meteriod is made incandescent by friction with the earth's atmosphere.  2. A meteoroid.  3. An atmospheric phenomenon, such as a rainbow, lightning, or snow.

asteroid

as-ter-oid (as'te-roid) n. Astron. Any of numerous celestial bodies with characteristic diameters, between one and several hundred miles and orbits lying chiefly between Mars and Jupiter.

star (star) n. Astron. 1. A self-luminous, self-containing mass of gas in which the energy generated by nuclear reactions in the interior is balanced by the outflow of energy to the surface, and the inward-directed gravitational forces are balanced by the outward-directed gas and radiation pressures. 2. Any of the celestial bodies visible at night from the Earth as relatively stationary, usually twinkling points of light. 3. Something regarding as resembling a star. 4. A graphic design having five or more radiating points, often used as a symbol. 5. stars. (a) The constellations of the zodiac believed to influence personal destiny. (b) The planets in relation to the constellations.

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