The Planet Neptune Mass (kg) ........................................................... 1.02 x 10^26 Diameter (km) .................................................... 49528 Mean density (kg/m^3) ........................................ 1640 Escape velocity (m/sec) ....................................... 23300 Average distance from Sun (AU) ......................... 30.06 Rotation period (length of day in Earth hours) ....... 19.1 Revolution period (length of year in Earth years) ... 164.8 Obliquity (tilt of axis in degrees) ..........................