Comet Observatory

Comet Observatory is the hub area in Super Mario Galaxy and is ruled by Rosalina. She built it after she agreed to take care of the Apricot Luma in the past. Soon, more Lumas arrived when it was too big for them to fit and, and the Apricot Luma transformed into the Beacon that powers the Observatory.

Details
The Comet Observatory normally comes into orbit around the Mushroom World every 100 years, and during that time, the people of the Mushroom Kingdom celebrate the Star Festival, thinking that the Observatory is simply a comet.

The Comet Observatory can be accessed through a portal in Gateway Galaxy, or in various ways. The Grand Stars are used to power up its Beacon. It was once about to disintegrate by Script, but it was cancelled.

Domes
According to The Lumas, the domes are used to view the cosmos most of the time.
 * Terrace - Resembles an Earth-like atmosphere being grassy; has a small telescope on the corner of it's interior
 * Fountain - Exterior is made of stones and has water sprouting from its sides
 * Kitchen - Has brick walls with an eternally-smoking chimney on top, and has a sink and a fireplace
 * Bedroom - Has purple walls and a curtain that hangs outside (exterior); has a purple starry wallpaper, some curtains, and a large canopy bed (interior)
 * Engine Room - Looks simply like a large metal dome, while inside there are purple and blue pipes leading up from a steel mesh floor
 * Garden - Looks like a pink pearl with a golden decoration similar to a tiara on top

Others

 * Garage - docking area for small spacecraft (Commonly occupied by the Toad Brigade)
 * Library - works and looks similarly to other libraries but is simple; where Rosalina reads her Storybook to the other Lumas
 * Planet of Trials - small planet orbiting the Comet Observatory; only accessed with three Green Power Stars

Trivia

 * It is impossible to die in the Comet Observatory, as anyone will be envolped in an energy-like bubble to heal and save him/her/it.
 * Despite being stated that it was too big for 2 characters, Rosalina still stayed after the events of The Room of Super Mario Galaxy for the sake of protecting it until more Lumas are reborn. She later came back in The Lair of the Dark Star after doing so.