Light Years

The Distance Light Travels in One Year

One light year (1 ly) is the distance that light travels in one year. In one second light travels 186,282 miles or 299,793 km. Since there are in a tropical year about 31,569,260 seconds, we can find the length of a light year by multiplying velocity by time to give 5.88 trillion miles (9.46 trillion km). This is a distance of about 63,240 AU.

The distance between stars is vast. The nearest star to us, Proxima Centauri lies at a distance of 4.22 ly from us. This represents a distance of 24.8 trillion miles.

Another commonly used unit of distance is the parsec. One parsec (1 pc) represents a distance of 3.26 ly.  


Copyright © 1998 - 2010 by Arnold V. Lesikar,
Professor Emeritus
Dept. of Physics, Astronomy, and Engineering Science,
St. Cloud State University,St. Cloud, MN 56301-4498

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