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Mercury
Mercury is the closest planet to the Sun. It is smaller than the moons Ganymede and Titan but larger than the planet Pluto. It is heavily cratered, showing impact scars from countless bombardments by meteoroids. Old lava flows and quake faults also mark its crust. Mercury has no atmosphere, but surprisingly, scientists have found evidence for a polar ice cap on this hot little globe. Mercury was explored in three flybys by the Mariner 10 spacecraft in 1974 and 1975.
Planet Profile
Mass (kg)............................................3.3 x 10^23 Diameter (km)........................................4878 Mean density (kg/m^3) ...............................5420 Escape velocity (m/sec)..............................4300
Average distance from Sun (AU).......................0.387
Rotation period (length of day in Earth days)........58.65
Revolution period (length of year in Earth days).....87.97
Obliquity (tilt of axis in degrees)..................0
Orbit inclination (degrees)..........................7
Orbit eccentricity (deviation from circular).........0.206
Mean surface temperature (K).........................452
Maximum surface temperature (K)......................700
Minimum surface temperature (K)......................100
Visual geometric albedo
(reflectivity)...............0.12
Largest known surface feature........................Caloris Basin (1350 km
diameter)
Atmospheric components...............................trace amounts of hydrogen
and helium
- Full specification and planet images for Mercury (courtesy of NASA)
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