Return to Astronomy Index PageLight Year
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A light year (Ly) is the distance that light travels in one year. Light travels at 186,282 miles/sec and does not speed up or slow down it remains constant! Calculating the actual distance that light travels in one year is simple:
186,282 miles/sec X 60 sec/1min X 60min/1hr X 24 hr/1day X 365.25 days/ 1year = 5,878,612,843,200 miles
A light year is practical for measuring distances between stars and nearby galaxies but not measuring distances within the solar system.