Super Mario Galaxy - 120 Stars

Ghostly Galaxy
Luigi and the Haunted Mansion
A Very Spooky Sprint
Beware of Bouldergeist
Bouldergeist Daredevil Run
Matter Splatter Mansion
Purple Coins in the Bone Pen

Buoy Base / Bubble Breeze Galaxies
Floating Fortress / Secret of Buoy Base / Through the Poison Swamp

For this observatory's boss, see the boss stars page.