Space Junk Galaxy is a galaxy in Super Mario Galaxy. It is located in the Comet Observatory's Fountain. Hence its name, this remote looking galaxy contains random floating objects, or "space junk". Mario can enter the galaxy if he has 9 Power Stars in his possession, including the Grand Stars from the Gateway Galaxy and Bowser Jr.'s Robot Reactor. In the mission titled "Yoshi's Unexpected Appearance", a wooden planetoid in the shape of Yoshi's head appears.
- Pull Star Path: Mario must navigate the galaxy using Pull Stars as his main mode of travel.
- Kamella's Airship Attack: Kamella and her troops have torn their way into the galaxy. Can Mario repel the airship before she takes the galaxy over?
- Tarantox's Tangled Web: Mario makes his way to the space graveyard within whose depths Tarantox makes his lair. Can our hero end the monster's reign of terror to allow reconstruction?
- Yoshi's Unexpected Appearance (Secret): Feeding the Hungry Luma 50 Star Bits will create the Yoshi Head Planet. Mario must rid the planet of Goombas. These Goombas give nothing upon their defeat, though stomping any 8 in a row gives a 1-UP, and continuing the chain will give extra lives.
- Prankster Comets:
- Pull Star Path Speed Run (Speedy Comet): Mario attempts Pull Star Path again, but with four minutes on the clock!
- Purple Coin Spacewalk (Purple Comet): Mario runs around the Assembly Block region to grab 10 groups which each contain 10 purple Coins. (100 total) Time limit: 2 minutes.
Starting Planet (Star Dust Start Planet)
This small planet is a square chunk of metal whose gravity is standard. It has a glass core that slightly resembles the next planet: a cylindrical hunk of glass.
Pull Star Asteroids (G Tutorial Capture Zone)
This asteroid field is here to teach how to use Pull Stars.
Olimar's Ship Planets
This planet is the first mission's penultimate planet. Resembling a tower, it has a T shape. It is long, and its appearance does not prevent it from having standard gravity, which pulls from all around.
Space Junk Area
The only planet here within this region is the Assembly Block planet, which stays there. Cosmic Platforms litter the area, tending to float on their own, but Mario can activate them by walking near their place. The Cosmic Platforms have their pattern shuffled in the Purple Comet.
Small Maze Crystal Planet
Prior to his assault on the Phantom Boss Spider Zone, Mario lands on this planet. It received its name from how it has a glass crust, but its core is a small maze.
Tarantox's Lair (Phantom Boss Spider Zone)
Tarantox makes his lair here. The spiders that dwell within this location give the area a haunting appearance, compounded with the Tension theme.
Yoshi Head Planet
- This Galaxy has one of the calmest theme songs ever: Space Junk Road, which has a piano soundtrack.