LIGHT-YEAR

in astronomy, unit of length equal to the distance light travels in one sidereal year. It is 9.461 × 1012 km (about 6 million million mi). Alpha Centauri and Proxima Centauri, the stars nearest our solar system, are about 4.3 light-years distant. See also parsec.

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Publication Information: Encyclopedia Article Title: Light-Year. Encyclopedia Title: The Columbia Encyclopedia, Sixth Edition. Publisher: Columbia University Press. Place of Publication: New York. Publication Year: 2004.