The Moon's Hidden Side

Explore why nearly the same side of the Moon faces Earth.

Day 0

View from above the Moon’s orbit

Earth near side far side

The Moon as seen from Earth

The near side

 

The red dot and flag mark the same spot on the near side. Times are approximate; sizes and distances are not to scale.

Learn more about the science

Yes, the Moon really does spin

Rotation means spinning on an axis. Revolution means traveling around another object. The Moon completes one rotation and one revolution around Earth in about 27.3 days. Because these motions take the same amount of time, nearly the same side, called the near side, faces Earth. The far side faces away. If the Moon orbited Earth without rotating, we would see different sides during one orbit.

In real life, our viewing angle changes slightly, letting us see a little around the edges. This apparent wobble is called libration; it is not shown in this simple model.

A full cycle of Moon phases takes about 29.5 days. Earth and the Moon are also traveling around the Sun, so the Moon must move a little farther to reach the same phase again.

Is there a permanently dark side of the Moon?

No whole side stays dark. Both the near side and the far side have day and night. At new moon, sunlight illuminates the far side. At full moon, sunlight illuminates the near side. Compare these two positions:

Earth Sunlight

New moon: sunlight illuminates the far side. The near side faces Earth but receives no direct sunlight.

How do we know what the far side looks like?

In 1959, the Luna 3 spacecraft returned the first photographs of the far side. Spacecraft have since mapped it in detail. In April 2026, Artemis II astronauts also observed and photographed the far side during their lunar flyby. Compare the two sides:

The near side of the Moon, with large dark plains among craters
Near sideMany dark plains formed when ancient lava filled large impact basins and cooled into rock.
The far side of the Moon, heavily cratered with few dark plains
Far sideMore visible craters and far fewer dark plains. Its thicker crust may help explain why less lava reached the surface.

Moon images: NASA

Explore the science: NASA: Moon Facts · NASA: Top Moon Questions · NASA: Moon Craters · NASA: Artemis II Lunar Flyby

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