Stunning, but one remark. If you look a little up of the planet further away you can see that those are actually coulds. You could have worked on those. The rest of the background is truly amazing. Nice effect overall.
If you don't mind, I'd like to use this as a background for an active/inactive RP'er page on my website (its for an outside site). Credit would be given on the page itself, of course. I have it ready to go, want your permission first, and I can provide you with a sample page if you wish.
Yeah, space-art is really tricky, so many different elements in it, and each demands a whole lot of time to experiment & gradually learn them. I use apophysis & photoshop with my own stuff, apo for rendering abstract fractals, and later postworked with photoshop. Those renders can be later used as part of nebulae, and also if done/manipulated right, as layers of light in the scene. Cloud-photography properly manipulated can also be used to build up nebulae. So I guess camera is one of the tools I use sometimes, along with apo/PS.
As for the photoshop-part, pretty much every aspect of the program is useful on space-art somehow, and huge amount of it´s tools comes in handy. Hard to explain all of them, and everyone creates space-art differently in any case. Best way is just to experiment and practise like crazy, not that many easy shortcuts exist.
Oh, and if this link works properly, here´s a pile of tutorials to start with, dig in if you dare.