Make it desktop resolution, and that would make a kick-ass desktop ice. The only thing I would change is the sun, some of the purplish lines look kind of odd coming out from it, I don't know if you intended that, but it seems to ruin the serenity of the image. But really, this is excellent, great job.
Its pretty good for being made from scratch, but there are a few problems that I see. The biggest problem is that stars are showing through the dark side of the moon/planet, which looks weird. The squiggly lines coming from the lens flare is a bit odd as well... I that the planet/moon should have a bit of an outer glow to it, to show that it has some form of atmosphere, and to make it look cooler. Overall, very good work. I like seeing people make things from scratch, it really highlights their artistic abilities. Keep up the good work!
Now I believe there is too much black in the lower left corner, you should find the exact dimensions you want for the planet, and still make stars but just don't overlap the dimensions that you set for the planet.
Icey, you do seem to love your sigs & the things of the likes. But other wise, I think the stars at a tad dull. Everything else looks fine to me.
Here's a tip for stars. New layer. Fill with gray. HSV noise. Make it look like a TV without channels. Blur. Then Colors> Levels. Mess around wilth the levels to get the amout of stars you want. Make sure you move the marker on the left, or middle. Not the one on the far right.