FactSentinel

The Moon has no permanently dark side. Every part of its surface receives sunlight during the course of a lunar day, which lasts about 29.5 Earth days. The confusion comes from the difference between the "far side" and the "dark side." The Moon is tidally locked to Earth, meaning it rotates once on its axis in the same time it takes to orbit our planet once. As a result, the same hemisphere always faces Earth, while the opposite hemisphere stays hidden from view. That hidden half is the far side, not a dark one.

The evidence is straightforward. During a new moon, the side facing Earth is unlit while the far side is fully illuminated by the Sun. During a full moon, the near side is lit and the far side is in darkness. Over a month, both hemispheres experience roughly two weeks of daylight followed by two weeks of night. Spacecraft have confirmed this directly. The Soviet Luna 3 probe photographed the far side in 1959, and later missions, including NASA's Lunar Reconnaissance Orbiter and China's Chang'e 4 lander, have mapped it in detail under sunlight.

The phrase likely stuck because the far side was unseen and mysterious for most of human history, and "dark" can mean "unknown." A small truth lies nearby: some deep craters near the lunar poles, such as parts of Shackleton Crater, are in permanent shadow and never receive direct sunlight. These are tiny regions, not an entire hemisphere.