Mercury is a dry, barren planet, with no surface water or atmosphere. It is the closest planet to the sun, having a year of only 88 earth days. It is so close in fact, it has been tidal locked with the sun, that is, one side is always facing the sun (Day) and the always faces away. (Night) Being the second smallest planets in the system, Mercury does not have, or has not sustained, an internal dynamo capable of creating a magnetosphere. Therefore, what little atmosphere it could contain with its small gravity, has been blown away by the solar wind long before mankind. With no water, no atmosphere, and no tectonic activity (Also caused by the lack of a dynamo) Mercury is a little-changing planet-wide desert. Mercury has no moons.