Super Mario Galaxy Tips

999 Starbits in Space Junk 2: Kamella's Airship Attack
Just find as many starbits as you could then on the airship that has the koopas for the bridge to go down, Go to the right of the airship and pound on the cage thing. LOTS OF S-BITS!
Keep repeating until you max out at 999. Then beat the boss, get the star. And look at that! JACKPOT! If you keep doing this kind of thing over 30 times, hopefully at the observatory you will max out at 9999 already.