light-year

/luyt"year', -year"/, n.
1. Astron. the distance traversed by light in one mean solar year, about 5.88 trillion mi. (9.46 trillion km): used as a unit in measuring stellar distances. Abbr.: lt-yr
2. light-years,
a. a very great distance, esp. in development or progress: The new computer is light-years ahead of the old one.
b. a very long time: It's been light-years since I've seen my childhood friends.
[1885-90]

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Distance traveled by light moving in a vacuum in one year, at its accepted speed of 186,282 mi/second (299,792 km/second).

It equals about 5.9 trillion mi (9.5 trillion km), 63,240 astronomical units, or 0.307 parsec.

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      in astronomy, the distance traveled by light moving in a vacuum in the course of one year, at its accepted velocity of 299,792,458 metres per second (186,282 miles per second). A light-year equals about 9.46073 × 1012 km (5.87863 × 1012 miles), or 63,241 astronomical units. About 3.262 light-years equal one parsec.

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Universalium. 2010.

Look at other dictionaries:

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