A light year is the distance that light travels in one year. Light travels at almost 300 thousand meters per second (299,792,458 meters per second, to be exact), therefore, in one Earth year it travels nearly ten million million kilometers.
If light could revolve around the Earth, it would spin 7 times in a second. Astronomers use the unit of measurement “light year” to measure how far away objects are in space. The closest star to us is approximately 4.3 light-years away.
Source: Chile Mobile Observatory - Marca Chile
