After months of practice. I present. No CGI pulgins all hand painted. A few probs though the shadows should be on the other side of the planets. and I still don't know how to do atmospheres. other wise enjoy.

That is the most unnatural looking pair of planets I've seen.

No plugins? Not even add noise? The stars must have been a *****. :p

By plugins I mean lunar cell and that glitero. Yeah I had ton use noise to make the stars. Oh Timewolf I took a look at some of your space art. Pretty good looking.

Not bad...

1. Planets look unnatural (like Echoman mentioned).
2. The Lighting pisses me off.

Fix it. Now.

Other than that, it's pretty good.

the planets have small white outlines! FICKS THAT!

Bah I will just restart it. More dune like :p

Anyway no silly textures needed. Just make colors inside circle Marqee (however its spelled) emboss it. sphereize it add some noise here and there. Give it lighting effects.

Nevulas are easy aswell. Justr take a big blob of transparent faded colors do some scribling. then take the eraser transparent fade that, and get creative with it.

[edit: this is about the first pic, you posted the new one while I was typing this]

The lighting on the planets don't make sense at all unless there is another bright star behind the camera.

The stars look alright. The Nebula look fine except for those in the bottom right corner, you might want to smudge a bit there to get rid of those hard edges. The bright star might use some smudging too, to make it less like an orb.
The composition is also a bit dull, try to spice things up a little by having things in front of another for example and maybe spice the texture of your planets up a little and make them both different.

You might want to look at these:

http://gallery.artofgregmartin.com/tuts_arts/making_a_star_field.html
http://gallery.artofgregmartin.com/tuts_arts/making_a_planet.html

I wouldn't suggest using exactly that technique (try some stuff out yourself too), but there is some very good stuff in there, that gives great effects!

The blue planets looked more like gas planets to me. They don't really look, 'unnatural', except the edges a bit.

Your planets look like rubber balls :/ Need detail.