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Planetary Facts

These facts about the planets and the Moon were taken from two sources: JPL's HORIZONS ephemeris generator and the National Space Science Data Center's planetary fact sheets, which are probably based on the HORIZONS data. Diameters for the giant planets are at the 1-bar altitude. Orbital distances for the Moon are measured relative to Earth's center.

Planetary Facts (Metric units)
PHYSICAL PROPERTIESMercuryVenusEarthMoonMarsJupiterSaturnUranusNeptune
Mean diameter (km) 4879 12,104 12,742 3475 6780 139,822 116,464 50,724 49,248
Equatorial & polar diameter (km) 4879 12,104 12,756
12,714
3475 6792
6752
142,984
133,708
120,536
108,728
51,118
49,946
49,528
48,682
Mass (1024kg) 0.330 4.87 5.97 0.073 0.642 1899 568 86.8 102
Density (kg/m3) 5427 5243 5515 3340 3933 1326 687 1270 1638
Gravity (m/s2) 3.7 8.9 9.8 1.6 3.7 23.1 9.0 8.7 11.0
Escape Velocity (km/s) 4.3 10.4 11.2 2.4 5.0 59.5 35.5 21.3 23.5
Hill sphere radius (planetary radii) 94 167 235   320 740 1100 2700 4700
Mean Temperature (C) 167 464 15 -20 -65 -110 -140 -195 -200
Geometric albedo 0.106 0.65 0.37 0.12 0.15 0.52 0.47 0.51 0.41
Surface Pressure (bars) 0 92 1 0 0.01 Unknown* Unknown* Unknown* Unknown*
ORBITAL MOTIONMercuryVenusEarthMoonMarsJupiterSaturnUranusNeptune
Rotation Period (hours) 1407.6 -5832.5 23.9 655.7 24.6 9.9 10.7 -17.2 16.1
Length of Day (hours) 4222.6 2802.0 24.0 708.7 24.7 9.9 10.7 17.2 16.1
Distance from Sun (106 km) 57.9 108.2 149.6 0.384* 227.9 778.6 1433.5 2872.5 4495.1
Perihelion (106 km) 46.0 107.5 147.1 0.363* 206.6 740.5 1352.6 2741.3 4444.5
Aphelion (106 km) 69.8 108.9 152.1 0.406* 249.2 816.6 1514.5 3003.6 4545.7
Orbital Period (days) 88.0 224.7 365.2 27.3 687.0 4331 10,747 30,589 59,800
Orbital Velocity (km/s) 47.9 35.0 29.8 1.0 24.1 13.1 9.7 6.8 5.4
Orbital Inclination (degrees) 7.0 3.4 0.0 5.1 1.9 1.3 2.5 0.8 1.8
Orbital Eccentricity 0.205 0.007 0.017 0.055 0.094 0.049 0.057 0.046 0.011
Axial Tilt (degrees) 0.01 177.4 23.4 6.7 25.2 3.1 26.7 97.8 28.3