Astronomical unit is a unit of length which describes the average distance between the Earth and the sun and is used to measure distances in the Solar system. This unit is accepted by the SI system. The exact numbers vary as Earth orbits the Sun from a maximum (aphelion) to a minimum (perihelion). Since 2012, the Astronomical unit has been defined as exactly equal to 149597870700 meters or about 150 million kilometers (93 million miles). You can convert Astronomical Units to other units here by enter amount of if into green input below. You can also check some basic conversions in Astronomical Units Conversion Table.