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Light Year (ly)

The light year is a unit of length, used for expressing interstellar and intergalactic distances in astronomy. Its symbol is ly.

ly
-ft

1 light year equals

Feet3.10391e+16 ft
Meters9.46073e+15 m
Miles5.87863e+12 mi
Kilometers9.46073e+12 km

About the light year

The light-year was first used by German astronomer Friedrich Bessel in 1838. It represents the distance light travels in one Julian year in vacuum.

In everyday use the light year appears in expressing interstellar and intergalactic distances in astronomy. As a point of reference: the nearest star to Earth (Proxima Centauri) is about 4.24 light-years away.

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