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.

---

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

---

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

---

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.

---

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

In a remarkable stroke of luck, NASA's Hubble Space Telescope observed a comet in the middle of breaking apart.

From Science Daily

This discovery was once seen as evidence that Earth may have been struck by a rare meteorite or comet.

From Science Daily

New research shows that the structure formed when an asteroid or comet struck the region roughly 43 to 46 million years ago.

From Science Daily

The telescope will search for difficult to detect near-Earth objects, including dark asteroids and comets that reflect very little visible light.

From Science Daily

They were horrendous —a thick mass of them on her head, a swarm trailing back like a comet’s tail as she flew through the air.

From Literature