Rightside Down Galaxy
From Lumapedia
Rightside Down Galaxy is the fourth accessible galaxy in the game alongside Fluffy Bluff Galaxy (fifth if you feed the Hungry Luma to unlock Flip-Swap Galaxy).
Rightside Down Galaxy puts Mario or Luigi into a 2D area where gravity changes from going up to going down throughout the galaxy.
Normal Stars
Any% Stars
Rightside Down 1 - Breaking the Laws of Gravity
Rightside Down Secret - The Great Crate Incinerator
Green Stars
The green stars here are typically done in the order 2, 1. Click here for more info on green star routing.
Routing Info
Mail Toad appears after 7 stars, which happens after Rightside Down Secret in the Current Fastest Any% Route, and after Rightside Down 1 in the Current Fastest 120/242 Route