Explore the Moon
Quick Stats
Moon Facts
| Bulk parameters | Moon | Ratio (Moon/Earth) |  |
| Mass (1024 kg) | 0.07349 | 0.0123 | |
| Volume (1010 km3) | 2.1958 | 0.0203 | |
| Equatorial radius (km) | 1738.1 | 0.2725 | |
| Polar radius (km) | 1736.0 | 0.2731 | |
| Volumetric mean radius (km) | 1737.1 | 0.2727 | |
| Ellipticity (Flattening) | 0.0012 | 0.36 | |
| Mean density (kg/m3) | 3350 | 0.607 | |
| Surface gravity (m/s2) | 1.62 | 0.165 | |
| Surface acceleration (m/s2) | 1.62 | 0.166 | |
| Escape velocity (km/s) | 2.38 | 0.213 | |
| GM (x 106 km3/s2) | 0.0049 | 0.0123 | |
| Bond albedo | 0.11 | 0.360 | |
| Visual geometric albedo | 0.12 | 0.330 | |
| Visual magnitude V(1,0) | +0.21 | - | |
| Solar irradiance (W/m2) | 1367.6 | 1.000 | |
| Black-body temperature (K) | 270.7 | 1.064 | |
| Topographic range (km) | 16 | 0.800 | |
| Moment of inertia (I/MR2) | 0.394 | 1.191 |
| Orbital parameters (for orbit about the Earth) | |
| 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 | |
| Mean Distance from Earth’s equator (km) | 378,000 |
| Apogee (km) | 357,000 |
| Perigee | 407,000 |
| Apparent diameter (seconds of arc) | 1896 |
| Apparent visual magnitude | -12.74 |
| Lunar Atmosphere | |
| 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 × 10-15 bar (2 × 10-12 torr) |
| Abundance at surface: | 2 × 105 particles/cm3 |
Estimated Composition in 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.
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