Rolling Coaster Galaxy

The Rolling Coaster Galaxy is one of the many galaxies found in Super Mario Galaxy 2. Like its name implies, this galaxy is like a roller coaster and, like in Rolling Masterpiece Galaxy, the player must roll a Star Ball to the end. Also, many Starshrooms appear along the way. It seems to be a reference to the Rainbow Road courses in the Mario Kart series. The name of the first mission in this galaxy confirms this.

Partway through the level, the path splits in two. One of the Toads says that the right path is for experts, while the other is assumed to be for beginners. In the "Purple Coins on the Rainbow Road" mission, the path for experts is the only path present. The only enemies found in this galaxy are Bob-ombs and Goombas.

The starting planet is a very long roller coaster-like path similar to Rainbow Road that the player must successfully reach the end of in order to break the Star Ball or the Purple Coin Ball. Just like it's name implies, the road is rainbow-colored and also has a few wooden sections at various intervals. There are also some rails, but not many apart from the ones on the starting platform. Only Bob-ombs and Goombas can be encountered on this planet.

A small planet found at the very end of the Rainbow Road Planet which contains only the mechanism for breaking the Star Ball and a Gearmo, who congratulates Mario on making it to the end of the course, and, in the case of the Purple Coins on the Rainbow Road level, will actually award Mario the Power Star when talked to.

Enemies

 * Bob-ombs
 * Goombas

The Rainbow Road Roll
To complete this mission, the player first needs to get on top of the Star Ball at the starting platform. Then, they have to use it to roll down the Rainbow Road Planet. They must avoid falling off the sides of the planet or running into Bob-ombs, which could cause them to fall off the side. When the player makes it to the end of the Rainbow Road Planet, they will land on the Ending Planet, where they will find a green hole. They must roll the Star Ball into it to release the Power Star.


 * Enemies
 * Bob-ombs
 * Goombas
 * Planets Visited
 * Starting Planet
 * Ending Planet

Purple Coins on the Rainbow Road
When the Prankster Comet has been unlocked, the player will find a Purple Coin Ball at the starting planet as opposed to the normal Star Ball. The player must follow the same path as in the first mission, except for the fact that they will only be able to follow the path for experts when the course splits in two, instead of choosing either one to follow. Obviously, the player must also make sure to collect at least 100 of the 110 Purple Coins found on the Rainbow Road Planet. If they are able to collect at least 100 Purple Coins within the time limit and successfully make it to the Ending Planet, then a Gearmo will reward Mario with a Power Star. If not, the player will have to start the level over.


 * Enemies
 * None
 * Planets Visited
 * Starting Planet
 * Ending Planet

Green Star 1
The first Green Star is located near the beginning of the Rainbow Road Planet. Taking the regular way and not the expert way, the player must stay in the middle of the coursec in order to reach it. Mario has to do his best to stay in the middle and avoid to many Bob-ombs and Goombas. If done correctly, the player should have Mario rolling up a bumpy slope. Just before Mario drops off the end of the slope, the player must use the momentum of the Star Ball and jump into the air directly onto the star. If Mario fails, he can roll right back up again (if he's careful).


 * Enemies
 * Bob-ombs
 * Goombas
 * Planets Visited
 * Starting Planet

Green Star 2
The last Green Star is near the end of the Rainbow Road Planet, just before the Ending Planet. It is positioned at the right side of the course, hovering in the air. In order for Mario to reach it, the player must either carefully use the momentum of the course to land on the star or jump before reaching the edge. If done correctly, Mario should easily grab the star instead of falling off the course.


 * Enemies
 * Bob-ombs
 * Goombas
 * Planets Visited
 * Starting Planet

Trivia

 * This galaxy uses the same music from The Princess's Secret Slide level in Super Mario 64 as its main music, which speeds up as the Star Ball rolls faster.
 * The levels in the galaxy include the name "Rainbow Road", which is the name of many different courses in the Mario Kart series. Even in other languages, the mission names are translated with their corresponding equivalent of "Rainbow Road". It's possible that the galaxy is indeed a reference to both them, and based on the music, to Rainbow Ride.