Far side of the Moon

Does the Moon have a dark side?

Q: Does the Moon have a dark side?

No. The Moon has a far side — the half that never faces Earth — but it gets exactly as much sunlight as the side we see. During a new moon, the far side is in full daylight. The “dark” in “dark side” only ever meant unseen, and it stopped being unseen in 1959.

No — and the two words hiding inside the question are doing different jobs. The Moon has a far side, the half that never faces Earth, because it turns once per orbit. And it has a dark side — whichever half is in night right now — exactly as Earth does. They are only the same half at full moon. At new moon the far side is in full daylight while the face we know is dark. “Dark” only ever meant unseen, and it stopped being unseen in 1959, when the first spacecraft flew around and photographed it.

The Moon right now. Which face points at Earth and which face points at the Sun are two different questions — the picture answers both at once.

Far is about us; dark is about the Sun

“Far side” names a fixed half of the Moon — the same terrain, always turned away from Earth. “Dark side” can only honestly name a moving half: wherever it is currently night, which sweeps right around the Moon every month the same way night sweeps around Earth every day. A fixed name and a moving name can’t be the same thing, and the phases prove it: every crescent you have ever seen is sunlight spilling onto the far side.

Why one side hides at all

The Moon spins exactly once per trip around us — not by coincidence, but because Earth’s gravity braked it into step over billions of years, which is tidal locking. So one hemisphere faces us for good. Almost for good: the orbit’s slight ellipse and tilt let us peek a little around the edges — libration — so about 59% of the Moon is visible from Earth over time.

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What the far side is actually like

Different, not darker. It has almost none of the smooth dark lava plains that make the face we see look like a face — it is paler, more heavily cratered, with a thicker crust, and why the two halves differ so much is still an open question. It is also the quietest radio environment a telescope could ask for, shielded from every transmitter on Earth by 3,500 km of rock, which is why astronomers keep proposing observatories there. The first photographs came from Luna 3 in 1959; the first landing on the far side came sixty years later, in 2019.

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