Neptune Diameter.... 49,528 km Mass (Earth = 1).... 17.14 Distance in AU's from sun.... 30.00 Rotation period (length of day in Earth hours).... 19.1 Revolution period (length of year in Earth years).... 164.8 Mean surface temperature.... -225.0 (C) ... -373.0 (F) Number of moons.... 8 Light minutes from Sun.... 250.4 Light hours from Sun.... 4.2 Photo source: NASA'S Planetary PhotoJournal See credits for original photo information