A Basic Earth/Moon Comparison Relative Earth and Moon Sizes to Scale(Distance between them is not to scale.) ``` THE MOON (LUNA) - SOME BASIC PHYSICAL DATA - NASA/JPL ====================================================================== LUNAR RADIUS Polar = 1736.0 km = 1078.7 mi Mean = 1737.1 km = 1079.4 mi Equatorial = 1738.1 km = 1080.0 mi ====================================================================== GEOCENTRIC DISTANCE Min = 363301 km = 225745 mi = perigee Mean = 384401 km = 238856 mi Max = 405502 km = 251967 mi = apogee ====================================================================== MEAN LUNAR SURFACE TEMPERATURES During the Day = 107 C = +227 F = 380 K During the Night = -153 C = -243 F = 216 K ====================================================================== SURFACE GRAVITATIONAL ACCELERATION 1.63 m/s² = 5.37 ft/s² ====================================================================== MOON/EARTH SURFACE GRAVITY RATIO 1.63 / 9.81 = 0.166 This means that on the moon, any person or object would have only about 1/6 as much gravitational weight as experienced on Earth. The Earth is only about 4 times 'larger' than the moon, but it contains some 81.3 times more material mass and about 6 times the gravity at the surface. ====================================================================== LUNAR ESCAPE VELOCITY 2.38 km/s = 1.48 mi/s = 8570 km/h = 5330 mi/h ====================================================================== ATMOSPHERE There is no air mostly due to the low gravity being insufficient to retain an atmosphere in such close proximity to the sun and no means of sufficient replenishment even if it did at one time. Gravity and temperature are very important factors involved in the long-term retention of an atmosphere. ``` Jay Tanner - 2014