Key Vocabulary in Astronomy

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Asteroid

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A small rocky body orbiting the sun, found mainly between the orbits of Mars and Jupiter in the asteroid belt.

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Comet

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A celestial object consisting of a nucleus of ice and dust. When near the sun, a 'tail' of gas and dust particles pointing away from the sun is visible.

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Dwarf Planet

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A celestial body resembling a small planet but lacking certain technical criteria that are required for it to be classed as such.

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Gas Giant

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A large planet of relatively low density consisting predominantly of hydrogen and helium, such as Jupiter, Saturn, Uranus, or Neptune.

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Meteor

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A small body of matter from outer space that enters the earth's atmosphere, becoming incandescent as a result of friction and appearing as a streak of light.

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Meteoroid

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A small particle from a comet or asteroid orbiting the sun.

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Meteorite

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A meteor that survives its passage through the earth's atmosphere such that part of it strikes the ground.

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Revolution

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The movement of an object in a circular or elliptical course around another or about an axis or center.

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Solar System

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The collection of eight planets and their moons in orbit around the sun, together with smaller bodies such as asteroids, meteoroids, and comets.

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Telescope

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An optical instrument designed to make distant objects appear nearer, containing an arrangement of lenses or of curved mirrors and lenses.