Each world has multiple power stars (between 1 and 4), and when you go to the world, you choose which power star to obtain. When you obtain a star, it turns yellow on the level select screen for each world. Beat 8 levels (which is not 8 worlds).
You don't! There are no red stars on Super Mario Galaxy 2
There is currently no Super Mario Galaxy 3. If you mean Super Mario Galaxy 2 there are 242 stars.
well super Mario galaxy 1 doesnt have Yoshi and super Mario galaxy 2 does.super Mario galaxy 2 has an icon for rossalina when you get 240 stars. super Mario galaxy 2 has coment medals which you get in the gane in all the galaxys super Mario galxy 1 you can play as Mario and lugi but in order to play as lugi you have to get 120 stars as Mario and in super Mario galaxy 2 you can play as luigi after you beat tall trunk galaky.
By completing missions
you smd.
there red
dunnoooooo
super Mario galaxy 2
there are 49 Galaxy's including the grand master galaxy
Bowser
120.
In Super Mario Galaxy 1 you can get 121 power stars, but in Super Mario Galaxy 2 the star gauge can hold 240 stars.