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light year |
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light year The distance light travels in one year, which is approximately 5.9 quadrillion miles. Abbreviated "ly," light years are used to measure distances in the universe. For example, the galaxy is presumed to be about 100 ly across. Proxima Centauri, at about 4.22 ly from the sun, is the closest star to the sun.It's About Distance, Not Time Because the word "year" is used, light years are often erroneously used to measure time. The phrase "I spent light years doing that" might sound triumphant, but it is like saying "I spent a million miles doing that." light year a unit of distance used in astronomy, equal to the distance travelled by light in one year, i.e. 9.4607 × 1012 kilometres or 0.3066 parsecs Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
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