| Mercury |
Earth |
Ratio (Mercury/Earth) |
|
|---|---|---|---|
| Mass (1024 kg) | 0.33010 | 5.9722 | 0.0553 |
| Volume (1010 km3) | 6.083 | 108.321 | 0.0562 |
| Equatorial radius (km) | 2440.5 | 6378.1 | 0.383 |
| Polar radius (km) | 2438.3 | 6356.8 | 0.384 |
| Volumetric mean radius (km) | 2439.7 | 6371.0 | 0.383 |
| Ellipticity (Flattening) | 0.0009 | 0.00335 | 0.269 |
| Mean density (kg/m3) | 5429 | 5513 | 0.985 |
| Surface gravity (mean) (m/s2) | 3.70 | 9.82 | 0.378 |
| Surface acceleration (eq.) (m/s2) | 3.70 | 9.78 | 0.378 |
| Surface acceleration (pole) (m/s2) | 3.71 | 9.83 | 0.377 |
| Escape velocity (km/s) | 4.3 | 11.2 | 0.384 |
| GM (x 106 km3/s2) | 0.022032 | 0.39860 | 0.0553 |
| Bond albedo | 0.068 | 0.294 | 0.231 |
| Geometric albedo | 0.142 | 0.434 | 0.327 |
| V-band magnitude V(1,0) | -0.613 | -3.99 | - |
| Solar irradiance (W/m2) | 9082.7 | 1361.0 | 6.674 |
| Black-body temperature (K) | 439.6 | 254.0 | 1.731 |
| Topographic range (km) | 7 | 20 | 0.350 |
| Moment of inertia (I/MR2) | 0.35 | 0.3308 | 1.058 |
| J2 (x 10-6) | 50.3 | 1082.63 | 0.055 |
| Number of natural satellites | 0 | 1 | |
| Planetary ring system | No | No |
| Mercury |
Earth |
Ratio (Mercury/Earth) |
|
|---|---|---|---|
| Semimajor axis (106 km) | 57.909 | 149.598 | 0.387 |
| Sidereal orbit period (days) | 87.969 | 365.256 | 0.241 |
| Tropical orbit period (days) | 87.968 | 365.242 | 0.241 |
| Perihelion (106 km) | 46.000 | 147.095 | 0.313 |
| Aphelion (106 km) | 69.818 | 152.100 | 0.459 |
| Synodic period (days) | 115.88 | - | - |
| Mean orbital velocity (km/s) | 47.36 | 29.78 | 1.590 |
| Max. orbital velocity (km/s) | 58.97 | 30.29 | 1.947 |
| Min. orbital velocity (km/s) | 38.86 | 29.29 | 1.327 |
| Orbit inclination (deg) | 7.004 | 0.000 | - |
| Orbit eccentricity | 0.2056 | 0.0167 | 12.311 |
| Sidereal rotation period (hrs) | 1407.6 | 23.9345 | 58.785 |
| Length of day (hrs) | 4222.6 | 24.0000 | 175.942 |
| Obliquity to orbit (deg) | 0.034 | 23.44 | 0.001 |
| Inclination of equator (deg) | 0.034 | 23.44 | 0.001 |
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 77.3
Maximum (106 km) 221.9
Apparent diameter from Earth
Maximum (seconds of arc) 13.0
Minimum (seconds of arc) 4.5
Maximum visual magnitude -2.43
Mean values at inferior conjunction with Earth
Distance from Earth (106 km) 91.69
Apparent diameter (seconds of arc) 11.0
Semimajor axis (AU) 0.38709893 Orbital eccentricity 0.20563069 Orbital inclination (deg) 7.00487 Longitude of ascending node (deg) 48.33167 Longitude of perihelion (deg) 77.45645 Mean Longitude (deg) 252.25084
Right Ascension: 281.010 - 0.033T Declination : 61.414 - 0.005T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date
Dipole field strength: 0.002 Gauss-Rh3
Dipole tilt to rotational axis: 0.0 degrees
Dipole Offset: 0.17 Rh
Surface (1 Rh) field strength: 0.0025 - 0.007 Gauss
Rh denotes Mercurian model radius, here defined to be 2,440 km
Surface pressure: <~5 x 10-15 bar (0.005 picobar) Average temperature: 440 K (167 C) (590-725 K, sunward side) Total mass of atmosphere: <~10000 kg Atmospheric composition (Column abundances in 106 per cm2): Sodium 12,000-200,000; Magnesium 100,000; Oxygen <40,000; Hydrogen 5000, Potassium 800-1300, Calcium 300-1000; Iron <300; Aluminum 15; and possible trace amounts of Argon (Ar), Carbon Dioxide (CO2), Water (H2O), Nitrogen (N2), Xenon (Xe), Krypton (Kr), Neon (Ne), Helium (He) (The atmosphere of Mercury is a surface bounded exosphere, essentially a vacuum. Values for some species can vary with local time or location, these are given as ranges.)
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