The bright tadpole-shaped area in this photograph of the Moon from Lunar Orbiter 2, a 1960s mission, is known as Reiner Gamma. It's in the Ocean of Storms, a giant impact basin paved with volcanic rock. The feature generates its own magnetic field, which is stronger than the Moon's overall field. Yet scientists don't yet understand why it's magnetic or how it was created. A planned mission will drop a robotic rover on the site in a few years, perhaps solving the mysteries about this enigmatic feature. [NASA]