The Earth is only intermittently visible from the Plaskett crater rim on the Moon. This makes it an ideal place to test the kind of autonomous manned base that will be needed on Mars. For most of the time, the astronauts will be deprived a view of their home planet.
The above is a view from Clementine of the full Earth over the lunar north pole. The crater with a central peak in the foreground is Plaskett. It is centred at 82.1° North and 174° East, and it is 109 kilometres in diameter. On Earth, Africa is clearly visible and nearly cloud free.