For using your mouse for this piece, you really outdid yourself. The details are astounding, especially for the Rosetta Sphere in the background. If I were judging, you would be first, no doubt.

Wow man, for using just a mouse this is really good! I know my hand would cramp doing those highlights without a tablet. My only constructive criticism is to add some highlights to those rocks. the light from the sphere should be creeping through the edges. the aura look surrounding the asteroids reminds me of like a psychic aura and with his hand out like that kinda looks like he's manipulating the rocks. I'm sure your hand would have fallen off though if you did do those highlights haha. Good Job!

Dude, all of our hands would hurt after this competition. XD
And the fact you did this with a mouse is... immense. The shading is so crisp, I'm surprised wasn't done with a drawing tablet.

Very well done! ^_^