comet

American  

[kom-it] / ˈkɒm ɪt /

noun

Astronomy.

1. a celestial body moving about the sun, usually in a highly eccentric orbit, consisting of a central mass surrounded by an envelope of dust and gas that may form a tail that streams away from the sun.

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comet British  

/ ˈkɒmɪt, kɒˈmɛtɪk /

noun

1. a celestial body that travels around the sun, usually in a highly elliptical orbit: thought to consist of a solid frozen nucleus part of which vaporizes on approaching the sun to form a gaseous luminous coma and a long luminous tail

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comet Scientific  

/ kŏm′ĭt /

1. A celestial object that orbits the Sun along an elongated path. A comet that is not near the Sun consists only of a nucleus—a solid core of frozen water, frozen gases, and dust. When a comet comes close to the Sun, its nucleus heats up and releases a gaseous coma that surrounds the nucleus. A comet forms a tail when solar heat or wind forces dust or gas off its coma, with the tail always streaming away from the Sun.

2. ◆ Short-period comets have orbital periods of less than 200 years and come from the region known as the Kuiper belt. Long-period comets have periods greater than 200 years and come from the Oort cloud.

3. See more at Kuiper belt Oort cloud See Note at solar system

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comet Cultural  

1. An object that enters the inner solar system, typically in a very elongated orbit around the sun. Material is boiled off from the comet by the heat of the sun, so that a characteristic tail is formed. The path of a comet can be in the form of an ellipse or a hyperbola. If it follows a hyperbolic path, it enters the solar system once and then leaves forever. If its path is an ellipse, it stays in orbit around the sun.

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Discover More

Comets were once believed to be omens, and their appearances in the sky were greatly feared or welcomed.

The most famous comet, Comet Halley (or Halley's comet), passes close to the Earth roughly every seventy-six years, most recently in 1986.

Other Word Forms

• cometary adjective
• cometic adjective
• cometical adjective
• cometlike adjective

Etymology

Origin of comet

1150–1200; Middle English comete < Anglo-French, Old French < Latin comētēs, comēta < Greek komḗtēs wearing long hair, equivalent to komē-, variant stem of komân to let one's hair grow (derivative of kómē hair) + -tēs agent suffix

Example Sentences

The Asteroids, Comets, and Meteorites research group at ICE-CSIC has spent more than a decade studying the physical and chemical properties of asteroid and comet surfaces.

From Science Daily

The UVS instrument was able to observe the comet during a window when viewing from Mars and Earth was difficult or not possible.

From Science Daily

In these events, an incoming object such as a comet detonates above the ground, releasing intense heat and shockwaves that reach Earth's surface.

From Science Daily

As opposed to this threatening metaphorical comet, the Northern “Star Spangled Atmosphere,” Lemen wrote, was “well regulated in its revolutions” and “its universal laws are too well Founded to be over thrown.”

From The Wall Street Journal

It could also test whether frequent comet activity replenishes the dust, a process studied by Steward researcher Virginie Faramaz-Gorka, who is also a co-author on the paper.

From Science Daily