The Moon always shows Earth the same face because its rotation matches its orbit.

The longer version

Tidal locking happened over immense spans of time. Earth's gravity raised bulges in the young Moon, and because the Moon spun faster than it orbited, those bulges were dragged slightly ahead of the line joining the two bodies. Earth then pulled back on them, acting as a brake.

Once the rotation slowed to match the orbital period, the bulges settled onto that line and the braking stopped. The same process affects many moons across the solar system. A small wobble called libration lets observers glimpse slightly more than half the lunar surface. The far side receives just as much daylight; it simply stays turned away from us.

Where this entry sits

The night sky looks calm, yet almost everything up there is moving, burning, or slowly changing. These facts cover planets, stars, the Moon, gravity, black holes, comets, and the story of how people began exploring beyond Earth. The full list sits on the Space and Sky page, where every entry is listed in order.