Some nice stuff, first one definitely needs a bit of work but the other two look ok.
Ok, this may be mostly a personal peeve, but I'd like to make a request here. Anybody who is doing artwork, or is thinking of doing artwork that is space related, please go download Celestia (
http://shatters.net/celestia/) and spend a few hours with it. It really is the most accurate simulation of the galaxy and our solar system out there, especially if you go to the motherlode (
http://www.celestiamotherlode.net/) and download some 2k, 4k, or 8k textures. You can get screenshots where you can't tell the difference between Celestia and the blue marble photos.
Now don't get me wrong, I'm all for being artistic and I definitely understand realism takes a backseat to other things, especially when it comes to games. But I also hail from a decent astronomy background, and it makes me happy to see things somewhat accurate. If nothing else, Celestia will give you a sense of scale. Like I said its mostly a personal thing, but it urks me when I see a planet with a huge moon hovering like 100 miles away (I'm not referring to any particular pictures here, just in general). Our moon orbits 240,000 miles away and is about 2/3rds the size of the continental US. Something like that would have to be orbiting at such an incredible rate to not crash straight to the surface.
Anyway, maybe this should go in rants and raves, but go download Celestia nonetheless.