The far side is not permanently dark
The far side is the lunar hemisphere that generally faces away from Earth. Because the Moon rotates once per orbit, observers on Earth see nearly the same hemisphere throughout the month.
The phrase “dark side” is misleading when it means the far side. Sunlight reaches both hemispheres. During new Moon, the near side is mostly dark while the far side is mostly sunlit. During Full Moon, the near side is sunlit and the far side is in night.
Why we can see a little more than half
The Moon’s orbit and orientation create small apparent rocking motions called libration. Over time, libration lets Earth observers see about 59 percent of the total lunar surface, although never all at once. The central far side remained unseen until spacecraft photographed it in 1959.
The two hemispheres look different
The near side contains broad dark volcanic plains called maria. The far side is more heavily cratered and has a much thicker crust with far fewer large maria. Scientists study this asymmetry to understand how the Moon cooled and how early impacts and Earth’s presence influenced its evolution.
“Dark” can still mean unexplored or radio-quiet in casual language, but for lighting the accurate terms are near side, far side, dayside, and nightside.
