A Lamp: Oblique Shadows
There is only one “lamp” on the Moon that can illuminate the landscape. This lamp also happens to be very far away—it is our Sun. It shines a light over the land on the Earth and the Moon, creating corresponding shadows. The Sun is so far away in relation to any setting on the Earth or Moon that we can actually treat it as if it were an infinite distance away. When we do this, we can assume that both the rays from the Sun and the shadows created by them run almost parallel to one another. Therefore, if you photograph the shadows, they should appear parallel in the picture.