Pls. take the following as just one opinion from a crazy old nerd:
If one is working at the junction of art and science, say, generating imagery for a game, or generating stills for Ken Burns pan-and-zooms during a Discovery Channel documentary on space, one's work should reflect the best current knowledge about a subject.
For example, as far as we know (ie, by optical or radar imaging), not one single comet appears the way you depicted yours - ie, almost perfectly spherical with a broken crust. In addition, the debris that comes off it would not be that uniform. Another problem is that your moon appears to be well inside of the Roche limit - in other words, if a moon ever got that close to its parent planet, it would almost immediately break up, etc. etc.
IMHO, to anyone who knows something about this subject, whether a sci-fi fan, a gamer or a scientist, this looks more like a
1950's Sci-Fi magazine cover art than something generated in 2013. It looks good -- very good -- but dated.
Now, if that's the look you were trying to achieve, great. But, if it wasn't, and you want to compete with other artists producing material in the same genre, I don't think it would do well.
Anyway, I know that sometimes things are just done for fun, but, you are so close to commercial level work, if you want to take it all the way, you have a good shot at it - just learn everything you can about the subject and then incorporate that into your art.
Anyway, just my two cents.
Cheers,
Tom M
