Planetary data for Neptune

mean distance from Sun 4,498,250,000 km (30.1 AU)

eccentricity of orbit 0.0086

inclination of orbit to ecliptic 1.77°

Neptunian year (sidereal period of revolution) 163.72 Earth years

visual magnitude at mean opposition 7.8

mean synodic period* 367.49 Earth days

mean orbital velocity 5.48 km/sec

equatorial radius** 24,764 km

polar radius** 24,340 km

mass 1.02 x 10²⁶ kg

mean density 1.64 g/cm³

gravity** 1,115 cm/sec²

escape velocity** 23.5 km/sec

rotation period (magnetic field) 16 hr 7 min

inclination of equator to orbit 29.6°

magnetic field strength at equator (mean) 0.14 gauss

tilt angle of magnetic axis 46.8°

offset of magnetic axis 0.55 of Neptune's radius

number of known moons 13

planetary ring system 6 rings, one containing several arcs

*Time required for the planet to return to the same position in the sky relative to the Sun as seen from Earth.

**Calculated for the altitude at which one bar of atmospheric pressure is exerted.