When I first played this game, I thought that the blue orb in the center was the planet, so I kept trying to block the asteroids with my actual planets. XD
After figuring out that I needed to keep my planets safe, the game was fun and very intuitive to play. I like how planets can both be rotating in the same direction, or different directions - it keeps the gameplay fresh. I wasn't able to maintain three planets though.
Overall, nice game!