I never knew Saturn had arms, 3 eyes and carried a handgun... You learn something new every day!
I liked the level structure; short, with a good variety of enemies and a bullet hell style boss (it's always fun to see the various bullet patterns). Short-but-sweet is what I'd call this game.
Also, the concept alone got a laugh out of me, and I was weirdly glad to see that all the planets were happy in the end.
Nice work!