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It's commonly stated that the moon's year is the same duration as its year and consequently there's a part of the moon that we never see from Earth.

Is that latter part correct, even if the former part is not strictly accurate?

If the day and year are not identical, why do we not see all of the moon eventually?

These questions were brought about by the news that a Chinese spacecraft has landed on the "dark side of the moon". That got me wondering whether the landing was completely autonomous or whether there was another module in orbit that could relay information from Earth (and indeed video back from the landing module.) Does anyone know?

News report yesterday said there was a comms satellite positioned in orbit round the earth further out than the moons orbit to allow relay of commands and telemetry from the dark side.

Dark Side if the Moon is a bit of a misnomer really :It gets plenty of sunshine during its orbits We just don’t see it. To imagine diabolical cold temperatures all the time due to lack of sun is false.

Peter

PaulB wrote:If the day and year are not identical, why do we not see all of the moon eventually?

Tidal locking (Wikipedia)

From space.com:

Targeting the far side of the moon, which due to tidal locking never faces the earth, required the prior launch of a relay satellite to the second Earth-moon Lagrange point some 65,000-85,000 kilometers beyond the moon to facilitate communications

The Far Side of the moon is the side away from earth, which we never get to see. The Dark Side of the moon is the half away from the sun, ie it's night on the moon's surface. We get to see the Dark side ,(or part of it) any time the moon isn't full.
Sometimes it's possible to see the Dark part, when it's illuminated by reflected earth light.
The lunar orbit and rotation are not in exact synchronization. The moon appears to rock about as a result, so in fact over time we get to see a bit more than half of it surface. This is called libration. We get to see 59% or so, from memory.

Oh yeah - I never quite forgave Pink Floyd.

lobstaboy wrote:
Oh yeah - I never quite forgave Pink Floyd.

Must be all the punishments we prefects heaped on Dave Gilmour, the cocky little sh it of the fifth form....

Peter