Encyclopedia >  Science and Technology  >  Astronomy and Space Exploration  >  Astronomy: General

light-year

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 Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on light-year from Fact Monster:

  • Measuring Motion - Measuring Motion Speed is the measure of motion. You can find it by dividing the distance covered ...
  • Miscellaneous Units of Measure - Miscellaneous Units of Measure Below is information about units of measure, including acre, bolt, ...
  • Hercules cluster - Hercules cluster Hercules cluster, giant globular star cluster in the northern constellation ...
  • Parkes - Parkes Parkes, town (1991 pop. 8,784), New South Wales, SE Australia. It is the site of a ...
  • Ring nebula - Ring nebula Ring nebula, planetary nebula in the northern constellation Lyra; cataloged as M57 or ...

See more Encyclopedia articles on: Astronomy: General