Background Mapping

I am trying to setup a simple starry-night environment/background with stars and a moon. What I would like to do is use Blender to generate the stars procedurally, using noise textures say, and then have a moon loaded from an image file sitting in some small patch of the sky. This part is what’s giving me trouble. I can’t seem to find a way to let blender know how I want the image mapped to the background. By default it just wraps it all the way around, which with my particular image results in a completely moon-covered sky. Obviously this is not what I’m looking for. I realize that I could probably edit the image to get closer to what I want, but I was hoping for a more elegant solution.

Is there something like UV mapping you can do for backgrounds to control how loaded images get projected? Maybe by referencing a UV-mapped sphere or something like that?

If all else fails I suppose I could just use a hugely scaled sphere instead of a world background, but once again, not ideal.

Ideas? Someone must have tried to do this before!

to me it seems that trying to do that in the 3dview is overkill. if you have the stars background ready, you can render it and insert the moon in the compositor. that would be much easier and quicker.
or use an entirely 2d approach, using a combination of image manipulation and compositing (photoshop/gimp, krita…).