Surface gravity is measured in units of acceleration, which, in the SI system, are meters per second squared. It may also be described as a multiple of the Earth's gravity, "g" = 9.80665 m/s. In astrophysics, the surface gravity may be expressed as log "g", which is obtained by first expressing the gravity in cgs units, where the unit of acceleration is centimeters per second squared, and then taking the base 10 logarithm.