Moon

:For other moons in the solar system see natural satellite. For the astrological meaning of the Moon, see Solar system in astrology. For other uses see Moon (disambiguation).

The two sides

The Moon is in a synchronous rotation with Earth, which means that one side of the Moon (the "near side") is permanently turned towards Earth. The other side, the "far side", mostly cannot be seen from Earth, except for small portions near the limb which can be seen occasionally due to libration. Most of the far side was completely unknown until the era of space probes. This synchronous rotation is a result of torque having slowed down the Moon's rotation in its early history, a process known as tidal locking.

Related Topics:
Synchronous rotation - Earth - Far side - Libration - Space probe - Torque - Tidal locking

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The far side is sometimes called the "dark side". In this case "dark" means "unknown and hidden" and not "lacking light"; in fact the far side receives (on average) as much sunlight as the near side, but at opposite times. Spacecraft are cut off from direct radio communication with the Earth when on the far side of the Moon.

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One distinguishing feature of the far side is its almost complete lack of maria (singular: mare), which are the dark albedo features.

Related Topics:
Maria - Albedo feature

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