Field guide · Reading the sky
The MoonThe far side of the Moon
No. The Moon keeps one face turned to us, so the other is always out of sight — but it gets just as much sunlight. It is the far side, not the dark one.
- Why we never see it
- The Moon turns once per orbit
- Sunlight
- The same as the near side
- First photographed
- 1959, by Luna 3
- First landing
- 2019, by Chang’e 4
The Moon turns once on its axis in exactly the time it takes to go once around the Earth, so the same face always points at us. It was not luck: long ago the Earth’s pull raised tides in the young Moon’s rock and braked its spin until the two matched. Astronomers call it tidal locking, and most big moons in the Solar System are locked to their planets the same way.
The side we never see still has day and night, each about two weeks long, like ours. The phases give it away. At full Moon our face is lit and the far side is in night; at new Moon, when the Moon looks dark to us, the far side is in full Sun. The part of the Moon in darkness is always the half turned away from the Sun, and that half goes round with the phases.
“Dark” once meant unknown, as in a dark continent on an old map. Nobody had seen the far side until the Soviet probe Luna 3 photographed it in October 1959. The first people to see it with their own eyes were the crew of Apollo 8 at Christmas 1968, and they had no radio while behind it — the Moon itself blocked the signal. The phrase stuck anyway, and Pink Floyd’s album of 1973 made it famous.
It turned out to look different. The near side has the big dark lava “seas”; the far side has almost none, because its crust is much thicker. The Moon also rocks a little as it goes round, so over a month we see about 59% of its surface, not half. China’s Chang’e 4 made the first landing on the far side in 2019, relaying its signal home through a satellite parked beyond the Moon.