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

/ 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 beltSee 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.

Notes

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.

Derived Forms

• ˈcometary, adjective

Other Words From

• com·et·ar·y [kom, -i-ter-ee], co·met·ic [k, uh, -, met, -ik], co·meti·cal adjective
• comet·like 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

All meteor showers originate from the debris field of comets or asteroids.

From BBC

A recent theory as to why Encke has such a large debris stream is that it was once part of a larger comet that broke up about 20,000 years ago.

From BBC

Visible until 7 November this year, the Orionids are an annual event and one of two meteor showers to originate from one of the best known comets in our Solar System - Halley's Comet.

From BBC

And when people are ogling the night sky this week, they should also keep an eye out for two additional celestial sightings — Saturn and the appearance of an ancient Oort cloud comet, she added.

From Los Angeles Times

This week marks the last opportunity to see the "comet of the century", before it disappears for another 80,000 years.

From BBC