| Orbital Elements | ||
| ||
| Mean distance from Sun | 57,910,000 km | = 0.3871 astronomical unit |
| Perihelion distance | 45,900,000 km | = 0.3068 astronomical unit |
| Aphelion distance | 69,700,000 km | = 0.4659 astronomical unit |
| Eccentricity of orbit | 0.2056 | |
| Inclination of orbit | 7.004° | relative to Earth's orbit |
| Period of orbit | 0.2408445 year | = 87.96845 days = 87:23:14:34 |
| Synodic period | 116 days | relative to Earth |
| Mean orbital speed | 47.88 km/s | |
| Minimum orbital speed | 38.86 km/s | |
| Maximum orbital speed | 58.98 km/s | |
| Physical Properties | ||
| ||
| Diameter | 4,879.4 km | = 0.3825 Earth diameter |
| Radius | 2,439.7 km | |
| Mass | 3.303 x 1023 kg | = 0.055271 Earth mass |
| Mean density | 5.42 g/cm3 | |
| Rotational period | 58.6462 days | = 58:15:30:30 = 2/3 of a Mercury year |
| Length of day | 175.9421 days | |
| Inclination of axis | 0.00° | relative to the axis of its orbit |
| Gravity at surface | 2.78 m/s2 | = 0.38 Earth gravity |
| Escape speed | 4.25 km/s | from surface |
| Visual geometric albedo | 0.10 | |
| Visual magnitude (Vo) | -1.9 | maximum, as seen from Earth |
| Mean surface temperature | 179°C | |
| Minimum surface temperature | -173°C | |
| Maximum surface temperature | 427°C | |
| Atmospheric pressure | 0.0 bars | Mercury has very little atmosphere |
| Atmosphere composition | ||
| ||
| Helium (He) | ||
| Sodium (Na) | ||
| Neon (Ne) | ||
| Argon (Ar) | ||
| Hydrogen (H) | ||
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for more about the Solar System
Jeff Root
September 4, 2003