This is my fantasy Earth
Done in Blender 2.69 , rendered in Internal
Wow … I made almost the same pic 
… though I had a bigger (closer by) asteroid and a smaller (further away) Earth
Both were BlenderGurus tutorial thingies
I like this one 
I really like this! Would look good as a desktop wallpaper 
Very well done
Andrew Price <3 haha
can i ask, what are you wanting to be the centre of focus, as you see, the chromatic aberration creates these lines which guide the eye into the centre of scene. if you overlay a 3x3 grid you see that the earth is in the centre piece yet the asteroid on the left inhabits on of the intersections, which is why i question this as my eyes are drawn to the asteroid and not the earth. Good scene, maybe work on the shot composition a bit more.