(inner-most and smallest planet in the solar system)
Mercury is the nearest solar system planet to the Sun
and the smallest.
- 0.39 AU - orbital radius.
- 0.2 orbital eccentricity.
- 0.055 Earth masses (about 4.5 × mass of the Moon).
- 0.38 Earth radii (about 1.4 Moon radii).
It has no moons.
It is a rocky planet with virtually no atmosphere, but has
a magnetic field that was unexpected.
It was thought to be tidally locked to rotate once
per orbit, but in fact rotates 1.5 times per orbit.
Two NASA spacecraft have visited: Mariner 10 flew by and MESSENGER
orbited it for over 10 years. A new ESA/JAXA mission,
BepiColombo will be launched in 2018 to reach Mercury in 2025.
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equilibrium condensation model
equilibrium temperature (Teq)
late heavy bombardment (LHB)