Light hour

A light hour (also written light-hour) is a unit of length. It is the distance travelled by light in vacuum in one hour. Based on the current definition of the metre a light-hour is equal to 1,079,252,848,800 metres (~1.08 Tm).

To give an example, Pluto's orbit's semi-major axis is about 5.473 light-hours.

See also: Light year