Thanks for the comments!

l3m0n5, thanks =P

And indeed, philipptr, your edit has less colours, but also less detail, the scene is much darker and, like daniel says, the craters of the moon were lost.

Again, thanks everyone for the comments =)

the black outline round the moon is a little harsh. The dark green you used for the horizon line might work better

Philipptr: I checked out your edit. It's a lot smoother, and it works it its own right, but you've lost the greenness of the sea, and the craters on the moon. I'm tempted to have a try myself...

erm. you dont NEED 22 colours for such a scene with this detail level. had a little fun with it to show that it works with less colours:
http://img521.imageshack.us/img521/4552/asduyb7.gif
(15 colours)

22 colors! really? i cant even tell, they're so uncontrasting u can barely tell the wide color variety, either way, i like it, good use of dithering on the shine of the moon :P