Astronomy Terms

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galaxy

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A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.

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celestial

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Having to do with the sky.

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Milky Way

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A large spiral galaxy that is home to Earth and the rest of our solar system, and about a trillion stars.

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Nebula

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A large cloud of dust and gas in space where stars are born.

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Elliptical Galaxy

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A galaxy shaped like a round or flattened ball, generally containing only old stars.

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spiral galaxy

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A galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern.

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Lenticular Galaxy

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A large group of stars that together make a shape that has a central bulge but no spiral arms.

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Irregular Galaxy

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A galaxy that has an undefined shape; irregular galaxies have large numbers of young stars and great amounts of gas and dust, usually found near larger galaxies.

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Supernova

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A gigantic explosion in which a massive star collapses and throws its outer layers into space.

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light year

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The distance that light travels in one year, about 9.5 million million kilometers.