imamartian said:
And what i don't get is... when the moon is at a quarter (say) how can we see the other 3 quarters, as a slightly less shaded thing? where's the light coming from?
Sooey has pretty much answered it already so I'll just fill in the details a bit:
1) When we see a crescent moon, anybody on the moon will see an almost full Earth.
2) The Earth is a lot bigger than the moon (about four times bigger) so a full Earth will look a lot bigger from the moon than the full moon does to us.
3) Because we have clouds, the Earth a lot more reflective than the moon.
Try to imagine something as bright as Venus but four times bigger than the moon. That's a lot of light! Actually, it wouldn't be that much because Venus is closer to the sun and completely wrapped in clouds but you get the idea.