Just like the first one, except better.
I thought of this too. It takes like, what, 6 grand stars to power the Observatory enough to go to the center of the universe? By this point Rosalina has enough grand stars to make a whole new universe. Power stars would've been a better reward.Been thinking about the hilarious downgrade Grand Stars got between the Galaxy games and Mario Kart Tour. In their original appearance they were the most-sought-after collectible, and were the biggest power source for the hub spacecraft and for Bowser's strongholds. Both games are beaten by grabbing a Grand Star. Now you just get them thrown at you left and right for mundane tasks like "do a rocket start" or "perform a slipstream" lmao