So, the Moon is not flat. You can see that the landing site is not on the center point of the Moon visible side. The curvate (yet again) cause the Earth to look so near to the Horizon. The picture is zoomed too.
You know how the moon is sometimes a crescent, and sometimes a circle? It's because of this very phenomenon. The angle the sun hits the moon changes and you can see more or less shadow depending on what part of the cycle the moon is in.