comet

[kom-it]

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.

comet

/ 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

comet

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

comet

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.

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

Word History and Origins

Origin of comet¹

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

Word History and Origins

Origin of comet¹

C13: from Old French comète, from Latin comēta, from Greek komētēs long-haired, from komē hair

Example Sentences

The team concluded that the object responsible was a meteorite rather than a comet.

Read more on Science Daily

Cosmic dust forms when stars explode or when comets break apart, and much of it carries a rare version of helium called helium-3 after passing near the sun.

Read more on Science Daily

But whenever the blazing comet that is Ms. Chenoweth is not center stage—which isn’t often, but often enough—“The Queen of Versailles” loses altitude.

Read more on The Wall Street Journal

A photographer who captured a comet in the night sky above the Yorkshire Dales said he spent weeks waiting for the perfect moment for the shot.

Read more on BBC

He was quick and quiet and covered in dark fur, except for a long, pale scar that streaked across his body like a comet.

Read more on Literature