| The Columbia Encyclopedia, Sixth Edition. 2001-07. |
| 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. |
| The Columbia Encyclopedia, Sixth Edition. Copyright © 2007 Columbia University Press. |
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