Prankster Comet

Prankster Comets are celestial beings that occasionally descend upon a galaxy during the course of Super Mario Galaxy. While they are within the galaxy's orbit, a new challenge to obtain a Power Star will be presented; often a previous mission is used, but with an added criteria. Each of the main fifteen galaxies will present two comet challenges, one being specific to the level and the other being a Purple Comet. There are five kinds of Prankster Comets in total, as listed below:

Speedy Comet

The Speedy Comet is a red comet that challenges Mario to finish a previous mission within a time limit. If Mario runs out of time, he loses a life. Losing a life at any time during a Speedy Comet challenge will require Mario to start over from the beginning, despite any checkpoints he would have passed in the normal mission.

The galaxies that play host to the Speedy Comet are:

• Good Egg Galaxy - Dino Piranha Speed Run
• Space Junk Galaxy - Pull Star Speed Run
• Dusty Dune Galaxy - Sand Blast Speed Run
• Dreadnought Galaxy - Topman Tribe Speed Run

Cosmic Comet

The Cosmic Comet is a blue comet that triggers the creation of Cosmic Mario. Mario must race Cosmic Mario through a portion of the galaxy to reach a Power Star. If Cosmic Mario gets to the Power Star first, Mario will lose a life.

The galaxies that play host to the Cosmic Comet are:

• Honeyhive Galaxy - Honeyhive Cosmic Mario Race
• Freezeflame Galaxy - Frosty Cosmic Mario Race
• Gold Leaf Galaxy - Cosmic Mario Forest Race
• Sea Slide Galaxy - Underwater Cosmic Mario Race

Daredevil Comet

The Daredevil Comet is a silver comet that reduces Mario's health to one and challenges him to complete a mission without taking damage. It most often appears in conjunction with a boss fight, with the comet carrying Mario directly to the battle arena. The only exception is in the Melty Molten Galaxy, where Mario must complete the entire mission or be forced to restart from the beginning.

The galaxies that play host to the Daredevil Comet are:

• Battledome Galaxy - Topmaniac's Daredevil Run
• Ghostly Galaxy - Bouldergeist's Daredevil Run
• Gusty Garden Galaxy - Major Burrows's Daredevil Run
• Deep Dark Galaxy - Daredevil Run to the Ghost Ship
• Melty Molten Galaxy - Lava Spire Daredevil Run