light-year

[ lahyt-yeer, -yeer ]

noun

1. Astronomy. 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. : lt-yr
2. light-years,
   1. a very great distance, especially in development or progress:

      The new computer is light-years ahead of the old one.

   2. a very long time:

      It's been light-years since I've seen my childhood friends.

light year

noun

1. a unit of distance used in astronomy, equal to the distance travelled by light in one year, i.e. 9.4607 × 10 ¹²kilometres or 0.3066 parsecs

light-year

1. The distance that light travels in a vacuum in one year, equal to about 9.46 trillion km (5.88 trillion mi). Light-years are used in measuring interstellar and intergalactic distances.
2. Compare astronomical unit

light year

1. The distance traveled by light in a year (over five trillion miles); a unit for measuring distances outside the solar system . The star nearest to our sun , Alpha Centauri, is more than four light years away.

Word History and Origins

Origin of light-year¹

First recorded in 1885–90

Example Sentences

One was his debut, “Boxcar Sessions,” an incredibly left-of-center release that was still definitely rooted in hip-hop, though it still sounded light-years ahead of its time.

From Los Angeles Times

The exact intensity of Tsuchinshan-ATLAS’s brightness is tough to predict; the comet is still light-years away from Earth, after all.

From Los Angeles Times

Instead of orbiting our Sun, this exoplanet revolves around a star in the Virgo constellation roughly 200 light-years from Earth.

From Salon

He also suggested that while poultry farmers have really upped their biosecurity in the past several years, the dairy industry is “light-years” behind when it comes to creating physical barriers.

From Los Angeles Times

Moreover, the variations detected in the galaxy, which is located 300 million light-years away in the constellation Virgo, are unlike any seen before, pointing astronomers towards a different explanation.

From Science Daily