Thanks Guys
I really should have thought about the 28 day period, that makes perfect sense!
The anticipated answer was very interesting though, thanks for that.
Why doesn't the Moon spin on its axis?
If someone is going to answer this with "Why should it" then Why does the Earth (and many planets) spin on their axis?
I'm sure someone told me the answer once, but I can't remember, and it's bugging me...