I like the idea and throwing asteroids around is more fun than expected. I'm not sure if it's just me, but the gameplay feels a bit slow. The asteroids spawn very far away and are closing in not very fast. You either could play close to earth which makes it more likely to miss an asteroid or accidentally hit it yourself. Or from further away which makes it easy to find them and I easily reached > 50 days.
Maybe limiting the grab range and adding warning signal when asteroids come close to the earth. This could balance the two playstyles more. Otherwise it was a nice game. Good job!