Bowser's Star Reactor

Bowser's Star Reactor is a galaxy located in Super Mario Galaxy and the first galaxy where Mario fights Bowser. Before that, he has to travel through a short level. The galaxy has lots of inaccessible Airships floating in the background; these can only be reached by hacking the game, which reveals they are solid. The theme is a remix of Bowser's Road from Super Mario 64.

Planets/Areas
NOTE: Unless otherwise noted, all names are unofficial.

Starting Planet
This Planet contains Fire Bars and a 1-Up Mushroom. When the player advances on the platforms, they will go into a loop. This planet also has a Thwomp and a flamethrower, and a platform that takes Mario to the Gravity Planet.

Gravity Planet
Here, Mario must be careful as to not fall off the platforms and into a black hole, because the gravity changes back and forth here due to the gravity fields. There are also more Fire Bars and a Thwomp here. At the end of this area is a platform leading to the stairs.

Stairway
In this area, there are stairs that lead to the platform where Mario fights Bowser. There are yet more Fire Bars, flamethrowers, and Thwomps that make getting to the top harder. After the Fire Bars, Bowser will appear and then he will try to throw fireballs at Mario. When the player reaches Bowser, they will be taken to the Magma Planet.

Star Reactor
This is the planet where Mario battles Bowser. When Bowser Ground Pounds the blue glass, lava will be exposed and burn his tail. The green plates can be used to block the shock waves Bowser makes. When Bowser is defeated, Mario will receive a Grand Star, unlocking the Kitchen.

Missions
This galaxy consists of only the following mission.

Names in other languages
Sistema Stellare di Bowser Bowsers Sternenfabrik