Great execution! Thank you.
The one thing I can comment is that the view of the black hole makes it easier to see when asteroids are coming from the sides. But if they come from up/down the visibility is lower and it's much more difficult. I'm not exactly sure how that could be handled... The naive solution would be to zoom out - that may decrease the difficulty however. The other option is to make the view round too? I guess it would also be zoomed out but that way the visibility would be the same in all directions (360 degrees). Anyways, the game is great as it is.