Why the Moon always shows the same face

Seen from Earth, the Moon always shows us almost the same side. That doesn’t mean it doesn’t rotate — quite the opposite.

Tidal locking

The Moon turns once on its axis in about 27.3 days — exactly the time it takes to orbit the Earth once. Because the two motions are in step, the same half always faces us.

Earth’s gravity caused this. It slightly “stretched” the Moon, and friction inside the Moon slowed its spin over millions of years until it matched the orbit. Astronomers call this tidal locking.

We still see more than half

The Moon’s orbit is slightly elongated and tilted, so from our point of view it “wobbles” a little. Thanks to this, over time we can see about 59% of its surface from Earth.

The “dark side of the Moon” isn’t always dark — it’s better called the far side. It gets as much sunlight as the near side; we just never see it.