This is a nice and very clear image, but the surface of the planet looks a bit boring: it looks flat, sort of like you just filled in a circle with a photoshop texture and some filters. If you did this (as opposed to painting it by hand) I would suggest attempting to paint this sort of thing: the rest of the image is very nicely done, so I am sure you are quite capable of it.

The rings around the planet look gaseous and not as uniform as one might see in a photo of, say, Saturn. However, the effect you HAVE achieved is soft, and looks quite nice, so I would say that you probably haven't overdone this aspect of the picture.

The waves also make this place look very turbulent, a contrast to the peaceful night sky and the planet. You have achieved a VERY nice effect with the texture of the waves as they thrash and spill around. The horizon looks a little odd, and normally I would suggest making it clearer or darker, but in this case it tends to separate the water from the sky.

I hope I have been helpful to you; this is a beautiful piece, and since you asked for Advanced Critique, I have done my best to give you such. Nice "first serious painting," too! Keep it up.

Wow, thanks for the in-depth response- yah the surface of the planet was what I started the image with and it was only my 2nd or 3rd planet I'd done w/ Photoshop- I've since greatly improved.
The horizon was the one part that I couldn't get to look right, and I think I went a little too crazy w/ blurring it out.

I think this looks Beuitiful. I always dreamed of Earth having to be very close to Saturn or other planets really really close. just looking up at the sky and you can see a bunch of planets in the sky. great work.

Thanks very much - that's very similar to what I was imagining when I did this. Just instead of Earth I was trying for some alien planet.

that is great