Battlerock Galaxy

The Battlerock Galaxy is a galaxy in the Wii game Super Mario Galaxy. The galaxy contains a multitude of floating metallic saucers and planet-sized rocks with Cannons. In some cases the main part of the galaxy will fire at Mario. Many robots and Bob-ombs appear in the galaxy. The inside of the Battlerock is very mechanical and technological. The galaxy also contains an area where three Lumas are being held. Topmaniac is a boss here.

Battlerock's Garbage Dump
This particular level is considered a secret level that can only be accessed by selecting the level called "Breaking Into Battlerock". You can access this area by feeding a Luma that can be found near the beginning. When you arrive here, a Gearmo will ask you if you could destroy all of his garbage in under 30 seconds. If you do so, you'll be rewarded with a star.

Luigi under the Saucer
In this level, you have to lure a Bullet Bill to a cage, holding Luigi. This is one of the three levels that has a Green Star.