Locked in synchronous rotation, the Moon always presents [ http://www.seds.org…] its well-known near side to Earth. But from lunar orbit, Apollo astronauts [ http://www.hq.nasa.…] also grew to know the Moon's [ http://lunar.arc.na…] far side. This sharp picture [ http://nssdc.gsfc.n…] from Apollo 16's mapping camera shows the eastern edge of the familiar near side (left) and the strange and heavily cratered far side of the Moon [ http://www.hawastso…]. Surprisingly, the rough and battered surface of the far side looks very different from the near side which is covered with smooth dark lunar maria [ http://volcano.und.…]. The likely explanation is that the far side crust is thicker, making it harder for molten material from the interior to flow to the surface and form the smooth maria.
