Currently at 71 stars and 22 hours, I could have beat it but I haven't.
It's funny, Rosalina asked me "do you want to go see your special one in the center of the universe" before I had even been to the fifth grand galaxy 
(I'm doing the fifth grand galaxy now, Toy Time Galaxy is AWESOME, but Spring Mario SUCKS)
Also, did anyone else notice that the music in the Astral Observatory changes when you restore all of the power? It adds more instruments I think. I kinda prefer the previous music, but the song is still amazing.
The game is pretty hard at first before you get the hang of it, then you get used to it and WHAM you're doing great. I went back to some of the earliest galaxies and missions and I found them really easy, when I had tons of difficulty before.
Top 3 favorite games: Super Mario Galaxy, The Sims 2 (PC), The Legend of Zelda: The Wind Waker
