Now a critique, the shading on the upper left planet needs to be twice as dark as it currently is. Likewise, the tiny planet closest to the sun should not have any black at all. Try and give all your planets some sort of atmostphere, a great trick for applying atmostphere is to make a selection that is the exact diameter of your planet, fill it with black, then set the blend mode to screen and give it an inner and other glow of light blue (adjusted accordingly to fit the light being emitted from the sun/light source. To give it even more life, create a second "atmosphere layer" on top and give it an outer glow of white, but with a much smaller spread. Then, take the two layers and put them in a folder with a layer mask and paint out the areas that aren't being hit by a light source with a large soft brush.
Thankyou! I am familiar with the black/screen blending mode technique, and I'm trying to move away from it because its often too easy to make things look "manufactured". Yes, atmosphere is important, and I'm still working on some ideas on how to improve. Thanks for your input!
I'd wondered if you were moving in that direction - more power to you!
I hit sort of an identity crisis (not sure if that's the correct name for it) 2 years ago where I started to question if my skills were more based on photoshop's filters and effects and not on my technique, so I spent 8 months doing sketch-a-days using photoshop and painter and just using the brush/eraser tools with a minimal amount of "undos" and layers. Otherwise, no filters, no effects, just brushwork. I didn't even use color correction. It really improved my technique and while I've gone back to using filters and effects, I find that I use them far more efficiently and effectively.
Any ways, my hat's off to you for developing your technique rather than relying on photoshop's filters, etc. Your work is showing the results and is only going to get better!