Why: moons orbit rate = moons rotation rate?

Google: lunar synchronous rotation

Google: lunar libration

Simple or complicated explanations available. We see glimpses of more than 50% of the lunar surface, due to its elliptical orbit and its slight tilt to the earth’s orbit around sun (ecliptic.)

The moon is tide-locked to the earth, meaning gravity has it stuck facing the same direction towards us all the time, hence the equality of rotation and revolution around us.

See http://en.wikipedia.org/wiki/Tidal_locking

@Zaku; not quite equal.

Yes, interesting point, thanks.

It’s all fascinating, isn’t it? Including the wonderful coincidence of the (almost) identical diameters of the sun and moon; giving us the lunar and solar partial and total eclipses, for the same reasons mentioned above. Sat.at 1:08 AM EST is the winter solstice.

I do find the moon fascinating, yes. Thanks for mentioning the solstice tonight – I’d been told it was last night, but I see my calendar agrees with you.

gail: strictly speaking, the moon and the sun do not have even slightly similar diameters… the sun is much, much, much larger. but i’m quite sure that you knew that, and you were in fact commenting on the equally amazing fact that the relative distance of the two bodies results in their apparent equality. truly amazing!

@Sam: you’re right, of course. I left out the word “apparent.” Thanks for catching my carelessness. G