A light year is the distance light travels in one year, or more specifically, the distance that a photon would travel, in free space and infinitely far away from any gravitational? or [magnetic field]?s, in the time it takes the Earth to complete on orbit of the Sun. It is approximately equal to 9.46 * 1015 meters ("10 million million kilometers"), because the speed of light in vacuum is 299,792,458 meters per second. |
A light year is the distance light travels in one year, or more specifically, the distance that a photon would travel, in free space and infinitely far away from any gravitational? or [magnetic field]?s, in one Julian year (365.25 days of 86400 SI seconds each). It is approximately equal to 9.46 * 1015 meters ("10 million million kilometers"), because the speed of light in vacuum is 299,792,458 meters per second. |