Ghostly Galaxy

The Ghostly Galaxy is a galaxy in Super Mario Galaxy. Many elements of this area are of a haunted theme, and Mario can even find Boo Mushrooms that turn him into a Boo. This galaxy also has the first appearance of Luigi in the game.

Starting Planet
The first thing Mario does in this galaxy is board a Toad ship, which always leads to the starting planet. The starting planet has about 3 Swoopers and 3 Pumpkin Goombas. There is a spike that contains a Rainbow Star when Spinned that could be used for destroying the Chain Chomp Heads in the first mission. In the third mission, there are 3 Scuttle Bugs. Each mission has a different Launch Star to get to the planets. There is a big gap in the middle of the planet that contains a Black Hole.

Mansion Planet
The Mansion Planet is a planet that resembles Luigi's Mansion in this galaxy. It is visited only in the first and third missions, though the third mission only has part of the Mansion. In the first mission, when Mario (or Luigi) enters the Mansion, he will come face-to-face to his first Boo in the game, providing that the player has not decided to skip this galaxy and go to another Boo containing galaxy (i.e. Deep Dark Galaxy). The Boo can be exterminated with a ray of light that gets turned on by a switch near the door. Also, there are some boxes near the edges of the room. Some of them contains Toads that give Mario information, while others give him Coins and Star Bits. There are also some Bowser Statues near the Crates.

There is a painting of a Boo on top of the stairs and when Mario goes near it, the Boo spouts out, and when it is defeated, a key appears. After the plumber enters the door, he is now faced the challenge of finding the 5 Star Chips that makes a Launch Star that goes to the upper floor of the mansion. While finding the Star Chips, some Pumpkin Heads are there to make life difficult for Mario. Once he is on the upper floor, he can go left and finds some Coins to add to his collection. But while Mario is collecting the 2 coins, he astonishingly sees Luigi trapped in a prison (or if the player is using Luigi, his "twin" is what's trapped). To save Luigi, Mario goes to the right and collects the Key to unlock the door. Going through it, he finds 2 Boos that appear in front of him, he kills them by Spinning them into a ray of light. Further on is an unreadable sign in the Boo language. Distraught, the hero goes forward to meet a ? Coin, and the first Boo Mushroom in the game appears right in front of the hero's eyes. Mario can now read the sign which reveals to be a Jill Board who teaches him how to be a Boo. The plumber then goes through the bars while invisible, and enters another room. He then encounters a Boo, who seems to find Mario incredibly attractive and decides to pursue him. When the Boo touches Mario, he loses his Boo powers and his true human identity is revealed, infuriating the Boo. The plumber then has to defeat the ghost by turning it into the light. Mario then continues on to get another Boo Mushroom near the corner, and uses it to pass through the walls to rescue Luigi.

In the third mission, only the first part of the mansion (with the Bowser statues) is seen. Instead of a Boo painting however, it is a Bomb Boo. It is used to destroy the statues to get coins, or to destroy the statue in the fireplace to proceed onwards. There are also the same boxes from the first mission, which contain coins, Star Bits, or Toads. When Mario enters the fireplace he is automatically inside a Launch Star, and is sent away to his next mission.

Bone Pen Planets
The Bone Pen Planets are planets prior and after to the real Bone Pen. They are your typical planets: round and able to walk "upside down". There are some trees with faces that have star bits on their branches on the first one. Also some  shells are girded along the ground which the plumber may Spin near to get some Star Bits. The Spooky Speedster is found here. The second one is much like the first one but it has a ring that is connected to the planet. The ring makes the other side of the planet hard to get to so Mario has to do a back flip over the ring to get there.

Cracked Wall Planets
When Mario gets to the 2nd Launch Star in Mission 3, he will arrive here. This Planet contains some Cosmic Scuttlebugs, Pumpkin Goombas, and a few Sling Pods. At the top, there is a Sling Star that will take Mario to the second Cracked Wall Planet. Here, the player must collect five Blue Star Chips to create Pull Stars to a Launch Star. This will take Mario to a bouncy Planet, then to the Bouldergeist Planet.

Bouldergeist Planet
This Planet is where Mario encounters the Boss, Bouldergeist. This planet is shaped like a circle with platforms leading up to it. There is also a Luma Shop here. When Mario fights Bouldergeist, Bomb Boos will appear. Besides this and a few coins, the Planet is empty. When Bouldergeist is beaten, the player will earn a Power Star.

Bone Pen
While techinaclly not a planet, it is is worth mentioning. It is where you race the Spooky Speedster and collect 100 Purple Coins in under 1 minute also 60 seconds. The Bone Pen is basically made up of Pull Star and bones so the player does not get out of the boundaries. After a while, there is a cow skull that lifts one of its 6 horns to stop the love of Princess Peach. There is also some meat that bounces Mario in a different direction.

Hollowed-out Planets
These planets are just the hollowed out rims of a planet, one of them has a pink bouncy ball in is center and mines around it. Most of them don't have gravity because there is no core but the one with the bouncy ball does.

Matter Splatter Area
This is an area very similar to the Matter Splatter Galaxy and may actually be part of the Matter Splatter Galaxy intertwined with the Ghostly Galaxy. It apparently is a crumbling mansion where Mario must follow a spotlight of matter to navigate through the mansion and get the power star.

Star Bit Shooter Planets
These are six small planets that shoot from three to five star bits each. Mario only passes by them and can only reach one of them by doing the pull star exploit glitch. They seem to be made of metal by close examination and are covered by a purple covering. If looked at closely you can see small red stars on them.

Spooky Speedster Planet
The Spooky Speedster Planet is the planet that the Spooky Speedster is found on. It has multiple trees and all of the members of the Toad Brigade are there. There are several star bits in the trees and you can start the race with the spooky speedster from here.

Finish Line Planet
This is the planet at the end of the race with the Spooky Speedster. There is a wall halfway through the planet which does not let Mario get across. The planet is where the Spooky Speedster will end up after he finishes the race, somehow the Spooky Speedster is able to transport himself and Mario from this planet back to the Spooky Speedster Planet if Mario wins the race. Another way back is to take the Warp Pipe at the top of the planet.

Pull Star Planets
These are two planets in the middle of the Race Area which are hollow and made out of glass. The only feature about them is that they have pull stars in the middle of them that will let Mario go across.

Race Area
This is the area where Mario races the Spooky Speedster using Pull Stars. It is ringed by bones and there are multiple obstacles made of bones all around it along with a cluster of mines at the end.

Luigi and the Haunted Mansion
At first, Mario starts off on the Toad Brigade's ship, but has to use a Launch Star to reach the pathway into the mansion. Pumpkin Goombas litter the pathway, so Mario must be careful. Boos are inside the mansion, but a switch activates a swinging beam of light, which Mario has to lure them into to defeat them and get the items they are guarding. One of the Boos has a key to get deeper into the mansion.

Soon, Star Chips can be collected to rebuild a Launch Star which will then be located in one of the windows where a black hole was before. Using the Launch Star, Mario is then launched into another part of the mansion, where Luigi is calling for help beyond an impassable window. Mario will have to find another way inside, where he discovers a new power-up, the Boo Mushroom. As Boo Mario, he needs to vanish to pass through the bars, but he must be careful as a beam of light which will make him lose the Boo Suit is in the next area. Mario needs to return to normal before he can speak with Luigi to get the Power Star.

Enemies

 * Boos
 * Pumpkin Heads
 * Goombas

Planets Visited

 * Starting Planet
 * Mansion Planet

A Very Spooky Sprint
To win this level's power star, Mario must defeat the Spooky Speedster in a race using Pull Stars. At the start, there is a big empty stretch of air that must be traversed using Pull Stars which will then blast Mario to the Spooky Speedster's planet. Mario must then race the Spooky Speedster along a race course ringed by bones using pull stars. If a pull star runs out, Mario will be pulled backwards through the race. There are multiple moving and non-moving bones all around the racecourse and multiple bones surrounded by a substance which will bounce Mario off meanwhile making a sound like a gong. There is a short-cut right after the first set of gong-bones in the form of a Spin Star which will fire Mario in front of the area with two glass planets that have pull stars in the center of them. The next area is full of mines that must be traveled through, a good strategy here would be to say no to the Spooky Speedster's request at the start and come to these mines then blow up some of them with Star Bits for a straight path through. If you have not completed the race yet you reach the finish line, there is a Warp Pipe to take you back to start. If you get there after the Spooky Speedster, you lose a life automatically, if you get there before him, he will take you back to start and give you the Power Star

Enemies

 * Pumpkin Heads
 * Goombas
 * Spooky Speedster

Planets Visited

 * Starting Planet
 * Spooky Speedster Planet
 * Race Area
 * Pull Star Planets
 * Finish Line Planet

Beware of Bouldergeist
Mario is informed by a member of the Toad Brigade that Luigi has been kidnapped by "The monster that lives up ahead". Mario will have to find his way to a circular stone platform and then meets Bouldergeist, a ghost with the ability to control stone. Mario will have to defeat Bouldergeist by using Bomb Boos to hit him in the main body part three times twice making a total of six times. Mario must dodge the rocks it uses and its hands in the second round meanwhile grabbing the Bomb Boos and hitting its body. After taking an amount of damage it eventually explodes, leaving behind a Power Star.

Enemies

 * Pumpkin Heads
 * Goombas
 * Bomb Boos
 * Bouldergeist (Boss)

Planets Visited

 * Starting Planet
 * Bouldergeist Planet

Bouldergeist's Daredevil Run
Very similar to Beware of Bouldergeist, however Mario starts on the boss planet with a health max. of 1. This mission, until completed, is only available while a Daredevil Comet is in orbit. It is a very hard star to get since there are many ways to get hurt.

Enemies

 * Bomb Boos
 * Bouldergeist (Boss)

Planets Visited

 * Bouldergeist Planet

Purple Coins in the Bone Pen
Mario starts off on a small planet with the "Bone Pen" in front of it. The Bone Pen features bones as walls, meaty bones as bumpers, spiky balls as obstacles, and Pull Stars for getting around. There are more than 100 Purple Coins, but only 100 have to be collected by the player before the Power Star appears in the center of the pen. This mission, until completed, is only available when a Purple Comet is in orbit, and has a one minute time limit, the strictest time limit of all Purple Comets.

Enemies
None.

Planets Visited

 * Bone Pen

Matter Splatter Mansion
A mission similar to the Matter Splatter Galaxy. While playing the level "A Very Spooky Sprint", the ring shaped planet containing pumpkin-headed Goombas also has two breakable stalagmites. One contains a Rainbow Star, and the other contains a Launch Star to the Matter Splatter Mansion (there is a sort of light around the one with the launch star). Platforms and rooms only exist when a sort of "Spot Light" comes over them. The Player will need to go through, getting keys, and unlocking doors to get through; eventually, there will be a Power Star behind one of the doors.

Enemies

 * Pumpkin Heads
 * Goombas
 * Swoopers
 * Cosmic Scuttle Bugs
 * Magikoopas

Planets Visited

 * Starting Planet
 * Matter Splatter Area

Trivia

 * In the level "Beware of Bouldergeist", a Toad at the beginning of the level said Bouldergeist kidnapped Luigi, but Luigi does not make an appearance in the level. It is believed, however that Bouldergeist is the creature that brought Luigi to the Ghostly Galaxy, as seen it the first level, "Luigi and the Haunted Mansion".
 * The level "Luigi and the Haunted Mansion" is an obvious reference to the game, Luigi's Mansion.
 * Strangely, when the player is Luigi, the trapped Luigi still shouts "Mario". This could either be something the developers missed, or the fact that he could have been expecting Mario to rescue him.
 * The mansion has three floors, with the first floor and third floor appearing in levels, and the second floor being unused.
 * Captain Olimar's spaceship appears close to the Bouldergeist planet.
 * The galaxy's BGM is the same as the underground levels from Super Mario Bros.