This is one of my absolute all-time favorite pictures of the Moon. It shows the far-northern crater Erlanger, which sits at 87° north latiutude. That close to the pole, the Sun hardly gets above the horizon. Shadows are always long, and only things poking up above the local landscape get illuminated well.
In this case, that's the rim of the crater! The floor and surrounding region are in the dark, but the rim sticks up just high enough to catch a few rays. On the flip side, the floor of many craters near the poles of the Moon never see sunlight and are locked in eternal frigidness. There may be ancient ice locked up under those crater bottoms, which would be very useful for future colonists.
Original post: Lunar boreal halo