What is a billion ?

[RichM63]

More like my kind of calculations, time for "a few" winks as its cloudy out. This old stargazing lark is best enjoyed for the sheer pleasure it provides , ill leave the more technical points to vulcans and the likes. By the way why do we only see one side of the moon ? He he thats one for an other wet night

Simples, because the mighty Pink Floyd have a monopoly on the other side. Amateur 'astrononomers' just can't afford the Royalty payments to view it..

[Ptarmigan]

'Gravitationally locked' is the term, I think.

You may need to find another puzzle.....weather is looking bad!

aka 'Tidally locked'

Another puzzle then :

Why is 'our side' full of maria (aka lava seas ? ) whereas the other side is mostly just pock-marked with craters

The professionals are still puzzled over that one.

Hands up, who remembers the Sky@Night when the first pics of the backside came through thanks to the Russians, Patrick's eyes almost popped out !

[Macavity]

Maybe we should just rewrite the language, based on SI units?

Giga, tera, peta, exa, zetta yotta - I had to check the last few...

Gillions, Tillions, Pillions(?), Exillions, Zillions(!), Yillions (nah)

[Kropster]

aka 'Tidally locked'

Another puzzle then :

Why is 'our side' full of maria (aka lava seas ? ) whereas the other side is mostly just pock-marked with craters

The professionals are still puzzled over that one.

Hands up, who remembers the Sky@Night when the first pics of the backside came through thanks to the Russians, Patrick's eyes almost popped out !

Maybe because the side facing away from Earth has been more exposed to bombardment?

p.s. I think they call it 'The Dark Side' not 'The Backside'.......which was considerred too rude at the time

[Ptarmigan]

p.s. I think they call it 'The Dark Side'

Ah! you spotted my little 'bon mot' 

Yes, differential bombardment is one.

There was also something about maybe there were two moons of different composition which merged. I thought a recent twin spacecraft gravity mission was going to look for this possibility but not sure what happened next ?

EDIT

I've just thought :

The different bombardment theory would require the moon to have been tidally locked for a really long time ? Way back 4 billion thousand million years to the Late Heavy Bombardment !?

[Kropster]

Perhaps stronger gravity on our side of the Moon caused crust fissures, allowing magma to flow?