Moon's Permanently Shadowed Regions

As you watch the Moon over the course of a month, you'll notice that different features are illuminated by the Sun at different times. However, there are some parts of the Moon that never see sunlight. These areas are called permanently shadowed regions, and they appear dark because unlike on the Earth, the axis of the Moon is nearly perpendicular to the direction of the sun's light. The result is that the bottoms of certain craters are never pointed toward the Sun, with some remaining dark for over two billion years. However, thanks to new data from NASA's Lunar Reconnaissance Orbiter, we can now see into these dark craters in incredible detail.