The far side of the Moon is the hemisphere of the Moon that always faces away from Earth. The far side's terrain is rugged, with a multitude of impact craters and relatively few flat lunar maria. It has one of the largest craters in the Solar System, the South Pole–Aitken basin. Although both sides of the moon experience two weeks of sunlight followed by two weeks of night, the far side is also referred to as the dark side of the Moon, originally in the sense of "unknown" rather than lack of light.