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

A century later, as a comet carrying disease and social unrest has upended the world, Afrofuturism may be more relevant than ever.

From Singularity Hub 

Meteor showers occur when flyby comets leave a dusty trail behind, so that when Earth runs through the trail, the dirt strikes our atmosphere, burns up and we see shooting stars.

From Washington Post

The outer disk of planetesimals—basically, a huge pile of leftover comets—was almost completely cleared out.

From Nautilus

When a comet’s ice vaporizes in sunlight, dust grains also fly off the comet.

From Science News

Scientists have known for over 100 years that comets can spark meteor showers, but it wasn’t until 1983 that researchers had the technology needed to connect the Geminids to a small asteroid, dubbed Phaethon because it swings so close to the sun.

From Science News

They found that there are roughly 1,900 hydrogen atoms for each deuterium atom in the water on Comet 67P.

From The Daily Beast

The probe appears to be sitting at the bottom of a "cliff" on the comet, but beyond that it's hard to tell.

From The Daily Beast

The basic approach went as planned: after separating from the Rosetta orbiter, Philae coasted slowly to the comet surface.

From The Daily Beast

Landing on any other world is hard, but Comet 67P is especially challenging, even apart from the low gravity.

From The Daily Beast

The comet is basically shaped like a rubber ducky, but with a much rougher surface.

From The Daily Beast

The Comet started on her first trip up the Arkansas, being the first steam boat that ascended that river.

From Project Gutenberg

By the time he reached the bridge the cylinders were purring softly and the Comet was going like a limited express.

From Project Gutenberg

Here Matt's wisdom in bringing Clip along, even at the loss of some speed on the Comet's part, was made manifest.

From Project Gutenberg

Jem, the driver of the roadster, crashed through the bushes just as the Comet was getting under its own headway.

From Project Gutenberg

With all the reserve power thrown into the machinery, the Comet made hard work of the hill.

From Project Gutenberg