Lunar Farside from Apollo 13
In April of 1970, after an explosion damaged their spacecraft, the Apollo 13 astronauts were forced to abandon their plans to make the third manned lunar landing. Still, while coasting around the moon in their desperate attempt to return to earth they were able to photograph the moon's far side. The large, dark, smooth looking feature on the left in this picture is known as the “Mare Moscoviense”. It was created by a lava flow filling in a large impact crater on the lunar surface. As suggested by the name, the Mare Moscoviense was first photographed by an early Soviet lunar probe. For more information about the picture see the NASA photo caption.