Prankster Comet

A Prankster Comet is a comet that sometimes circles galaxies in Super Mario Galaxy. If Mario goes to a galaxy with a Prankster Comet circling it, he will have to do a special challenge.

Speedy Comet
In a Speedy Comet challenge, Mario must get the Power Star before the time runs out.

Cosmic Comet
In a Cosmic Comet challenge, Mario must race Cosmic Mario, or Luigi must race Cosmic Luigi to the Power Star.

Daredevil Comet
In a Daredevil Comet challenge, Mario only has one health.

Fast Foe Comet
In a Fast Foe Comet challenge, all of the enemies move faster than normal.

Purple Comet
In a Purple Comet challenge, Mario must collect 100 Purple Coins. There is sometimes a time limit. They only appear after beating Bowser's Galaxy Reactor.