I liked the first one better, but a moon is a good idea. It's just...the way you implemented it, it looks like the moon was cut/pasted on rather than integrated into the image. It's like it's sitting on top of the light, unaffected by the neat gradient you've got going...you see? Like it's not in the same atmosphere. I really like the dithering and mountains, though.
If you put the moon there, I think that it'll be a bit right-heavy, since the right side of the image will have all this stuff (highest peak, moon, three clouds) y' know?