Astronomical Unit

An astronomical unit (AU) is the average distance between the Earth and the Sun. It is defined as exactly 149,597,871 km, and equals approximately 8 light-minutes. The unit is most commonly used to measure distances within our and other solar systems.

Mars is about 2.5 AU from the Sun, which means it is 2.5 times the distance from the Earth to the Sun, or approximately 375 million km from the Sun (149,597,871 km • 2.5).