A nice piece, I like your use of lighter lines to make it look smooth and shiny, it also gives it the impression that it is moving which is great for this piece for obvious reasons. The nebulas in the corners also are top notch, I like how you can see the stars through them making it more realistic.

My criticisms for this would be that I can't help but feel that it should be part of a bigger piece. Don't get me wrong it's brilliant I just think that it could have been more.