The atmoshpere looks a bit thick, but it's
only 3 or 4 pixels, and fades opaque.
The atmosphere isn't usually sitting there with
a white backdrop.
Here's a link to an OK moonrise pic.
http://www.space.com/php/multimedia/imagegallery/igviewer.php?imgid=55&gid=4
After looking at that, I'd think the air in your
model should be clearer a bit.
