definition comet
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comet A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up
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comet comet definition. 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.
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ASTRONOMY 4. nucleus - (astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail. astronomy, uranology-the branch of physics that studies celestial bodies and the universe as a whole.
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1. What is a Comet? Comets are small, fragile, irregularly shaped bodies composed of a mixture of non-volatile grains and frozen gases. Comets are composed of rock, dust, ice and frozen gases suc…h as carbon monoxide, carbon dioxide, methane, and ammonia. Sometimes called dirty snowballs, recent studies have shown that the ice of a comet is covered by a crust.
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About Comets What are the different parts of a comet? Every comet has a nucleus, a stable, porous central mass of ice, gas, and dust that if often between 1 and 10 kilometers (0.6 to 6 miles) in size. The ice is made of varying amounts of water, carbon dioxide, ammonia, and methane. The dust may contain hydrogen, oxygen, carbon, nitrogen, silica, and some metals.
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cometnoun  [ C] An opportunity may thus be presented of determining the mass of one of the largest comets on record, which may not again occur. Did not God do this very thing when he permitted the comet to strike the earth? However, the Church of England still embraced the idea that comets and eclipses were evidence of God's wrath. The comet will visit Mars first, and proceed to Mercury, Jupiter, Venus, and Saturn. The plague was thought to have been announced by a comet. (Definition of “comet” from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)
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What's the difference between asteroids, meteoroids, meteors, meteorites and comets? Comets are asteroid-like objects which are composed of ice, dust and rocky particles; that's why they are also called 'dirty snowballs'. The sizes of their nuclei vary between a few hundred metres to tens of kilometres in diameter; their visible tails can extend to above 150 million km in length.
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How do the terms comet, asteroid, meteoroid, meteor and meteorite differ? A comet is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind upon the nucleus of the comet.
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Comet Comet: Comet, a small body orbiting the Sun with a substantial fraction of its composition made up of volatile ices. When a comet comes close to the Sun, the ices sublimate (go directly from the solid to the gas phase) and form, along with entrained dust particles, a bright outflowing atmosphere around the comet nucleus known as a coma.
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What Is a Meteor? A meteor is the streak of bright light that can be seen from Earth when a meteorite enters the atmosphere. The actual object entering the atmosphere is called a meteorite, and it is usually a piece of an asteroid.
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How do the terms comet, asteroid, meteoroid, meteor and meteorite differ? Meteoroid-A small particle from an asteroid or comet orbiting the Sun. Meteor-A meteoroid that is observed as it burns up in the Earth’s atmosphere – a shooting star. Meteorite-A meteoroid that survives its passage through the Earth’s atmosphere and impacts the Earth’s surface.
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Comet A comet is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind upon the nucleus of the comet.iagram of a comet showing the dust trail, the dust tail (or antitail) and the ion gas tail, which is formed by the solar wind flow. Gas and snow jets on Comet Hartley 2. In the outer Solar System, comets remain frozen and inactive and are extremely difficult or impossible to detect from Earth due to their small size.
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comet Definition of comet for English Language Learners : an object in outer space that develops a long, bright tail when it passes near the sun COMET Defined for Kids
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Comet Facts Facts about comets. 1  Sometimes comets are referred to as “dirty snowballs” or “cosmic snowballs”. This is because they are composed mostly of ice, rock, gas and dust. 2  Comets orbit the Sun in elliptical paths – just like the planets. The path of a comet though is far more elliptical than that of any planet.
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Comet Facts Facts about comets. 1  Sometimes comets are referred to as “dirty snowballs” or “cosmic snowballs”. 2  Comets orbit the Sun in elliptical paths – just like the planets. 3  A comet has four components: a nucleus, a coma, a dust tail and an ion tail. 4  The nucleus of a comet contains the vast majority of its total mass. Comets have a halo when they move close to the Sun. What happens is the solar radiation vaporizes the ice and gas gas in the comet into a halo around it.
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comet By definition long-period comets remain gravitationally bound to the Sun; those comets that are ejected from the Solar System due to close passes by major planets are no longer properly considered as having periods.
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asteroid Definition of asteroid. 1  1 : any of the small rocky celestial bodies found especially between the orbits of Mars and Jupiter. 2  2 : starfish.
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Comet tail A comet's orbit showing the different directions of the gas and dust tails as the comet passes the Sun. In the outer Solar System, comets remain frozen and are extremely difficult or impossible to detect from Earth due to their small size.
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What is a comet? Comets are basically dusty snowballs which orbit the Sun. They are made of ices, such as water, carbon dioxide, ammonia and methane, mixed with dust. These materials came from the time when the Solar System was formed. Comets have an icy center (nucleus) surrounded by a large cloud of gas and dust (called the coma). The coma is created as the ice in the nucleus is warmed by the Sun and vaporizes. Comets can develop two tails as they travel closer to the Sun: a straight gas tail and a curved dust tail. The gas tail is created by the solar wind, pushing gas away from the comet's coma and pointing straight back from the Sun. The dust in the coma is not affected by magnetic fields but is vaporized by the Sun's heat, and forms a curved tail which follows the comet's orbit.
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comet Most comets are small Solar System bodies with elongated elliptical orbits that take them close to the Sun for a part of their orbit and then out into the further reaches of the Solar System for the remainder. Comets are often classified according to the length of their orbital periods: The longer the period the more elongated the ellipse.
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Glossary The name given to a tail when it points towards the sun. This is a rare event and typically occurs when the Earth crosses the plane of the comet’s orbit when that comet is relatively close to the sun and exhibiting notable tail activity.
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- Definition of comet written for English Language Learners from the Merriam-Webster Learner's Dictionary with audio pronunciations, usage examples, and count/noncount noun labels. Learner's Dictionary mobile search
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Solar System Comets are small Solar System bodies, typically only a few kilometres across, composed largely of volatile ices. They have highly eccentric orbits, generally a perihelion within the orbits of the inner planets and an aphelion far beyond Pluto.
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comet A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail.
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Comet tail Comet Holmes (17P/Holmes) in 2007 showing blue ion tail on right. Comet Lovejoy from orbit. A comet tail —and coma —are features visible in comets when they are illuminated by the Sun and may become visible from Earth when a comet passes through the inner Solar System.