I'd like to recommend that your graphics sort of match each other so it looks like it's for the same game. Cartoon asteroids with photorealistic earth, seem recycled. I'd recommend a menu, keyboard shortcuts, and an onscreen+keyboard restart. I need some way to play more than 1 game without hard reloading the webpage. There really need to be spawn zones, so asteroids literally don't spawn right on top of my player token.
My score isn't a reflection of you as a developer, but rather to show there's a lot of room to work with this submission.
This game follows a pretty standard reskin of the basic game tutorial, giving it a space theme and custom graphics is a starts. Lets see you integrate in some other things to really set this game apart from all the others.