Moon Earth Ratio (Moon/Earth) Mass (1024 kg) 0.07349 5.9736 0.0123 Volume (1010 km3) 2.1958 108.321 0.0203 Equatorial radius (km) 1738.1 6378.1 0.2725 Polar radius (km) 1736.0 6356.8 0.2731 Volumetric mean radius (km) 1737.1 6371.0 0.2727 Ellipticity (Flattening) 0.0012 0.00335 0.36 Mean density (kg/m3) 3350 5515 0.607 Surface gravity (m/s2) 1.62 9.80 0.165 Surface acceleration (m/s2) 1.62 9.78 0.166 Escape velocity (km/s) 2.38 11.2 0.213 GM (x 106 km3/s2) 0.0049 0.3986 0.0123 Bond albedo 0.11 0.306 0.360 Visual geometric albedo 0.12 0.367 0.330 Visual magnitude V(1,0) +0.21 -3.86 - Solar irradiance (W/m2) 1367.6 1367.6 1.000 Black-body temperature (K) 274.5 254.3 1.079 Topographic range (km) 16 20 0.800 Moment of inertia (I/MR2) 0.394 0.3308 1.191 J2 (x 10-6) 202.7 1082.63 0.187
Moon Semimajor axis (106 km) 0.3844 Perigee (106 km)* 0.3633 Apogee (106 km)* 0.4055 Revolution period (days) 27.3217 Synodic period (days) 29.53 Mean orbital velocity (km/s) 1.023 Max. orbital velocity (km/s) 1.076 Min. orbital velocity (km/s) 0.964 Inclination to ecliptic (deg) 5.145 Inclination to equator (deg) 18.28 - 28.58 Orbit eccentricity 0.0549 Sidereal rotation period (hrs) 655.728 Obliquity to orbit (deg) 6.68 Recession rate from Earth (cm/yr) 3.8 Mean values at opposition from Earth Distance from Earth (equator, km) 378,000 Apparent diameter (seconds of arc) 1896 Apparent visual magnitude -12.74 * These represent mean apogee and perigee for the lunar orbit. The orbit changes over the course of the year so the distance from the Moon to Earth roughly ranges from 357,000 km to 407,000 km.
Diurnal temperature range: >100 K to <400 K (roughly -250 F to +250 F) Total mass of atmosphere: ~25,000 kg Surface pressure (night): 3 x 10-15 bar (2 x 10-12 torr) Abundance at surface: 2 x 105 particles/cm3 Estimated Composition (particles per cubic cm): Helium 4 (4He) - 40,000 ; Neon 20 (20Ne) - 40,000 ; Hydrogen (H2) - 35,000 Argon 40 (40Ar) - 30,000 ; Neon 22 (22Ne) - 5,000 ; Argon 36 (36Ar) - 2,000 Methane - 1000 ; Ammonia - 1000 ; Carbon Dioxide (CO2) - 1000 Trace Oxygen (O+), Aluminum (Al+), Silicon (Si+) Possible Phosphorus (P+), Sodium (Na+), Magnesium (Mg+) Composition of the tenuous lunar atmosphere is poorly known and variable, these are estimates of the upper limits of the nighttime ambient atmosphere composition. Daytime levels were difficult to measure due to heating and outgassing of Apollo surface experiments.
For information on the Earth, see the Earth Fact Sheet.
Notes on the factsheets - definitions of parameters, units, notes on sub- and superscripts, etc.
Planetary Fact Table
- metric units
Planetary Fact Table
- U.S. units
Planetary Fact Table
- Earth ratio