Mercury Diameter.... 4,878 km Mass (Earth = 1).... 0.06 Distance in AU's from sun.... 0.39 Rotation period (length of day in Earth days).... 58.7 Revolution period (length of year in Earth days).... 88.0 Mean surface temperature.... 179.0 (C) ... 354.2 (F) Number of moons.... 0 Light minutes from Sun.... 3.2 Light hours from Sun.... 0.05 Photo source: NASA'S Planetary PhotoJournal See credits for original photo information