Prankster Comets are comets 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 bad challenge. They can be moved around by feeding a special Luma 20 Star Bits. In Super Mario Galaxy 2, however, Prankster Comets need to be summoned by a Comet Medal.
In a Speedy Comet challenge, Mario must get the Power Star before the time runs out. In Super Mario Galaxy 2, Speedy Comets reappear but there are clocks that add ten more seconds and less time to begin with.
- their cosmic counterparts to the Power Star. Cosmic Luigi takes more of the shortcuts than Cosmic Mario does. Cosmic Comets do not appear in Super Mario Galaxy 2. In a Cosmic Comet challenge, Mario or Luigi must race
- In a Daredevil Comet challenge, Mario has a maximum of one health point, and will usually fight a boss. Daredevil Comets reappear in Super Mario Galaxy 2.
Fast Foe Comet
- In a Fast Foe Comet challenge, all of the enemies move faster than normal. In Super Mario Galaxy 2, there are similar comets called Double Time Prankster Comets, where certain elements of the world switch faster.
- Purple Coins. There is sometimes a time limit. They only appear after beating Bowser's Galaxy Reactor in Super Mario Galaxy. Purple Comets reappear in Super Mario Galaxy 2. In a Purple Comet challenge, Mario must collect 100
In a Clone Comet challenge, Mario must attempt to complete a designated task whilst being followed by many Cosmic Clones. There can sometimes be a time limit added. These comets only appear in Super Mario Galaxy 2.
In a Romp Comet challenge, Mario must attempt to wipe out every enemy from a designated area using either an Item, or a Star. This must be completed within the time given. If Mario fails to complete this in time, he will have to restart. Once he has wiped out all the enemies, he is allowed to collect the Power Star. These comets only appear in Super Mario Galaxy 2.
Double Time Comet
In a Double Time Comet challenge, Mario must attempt to complete either a full level or a portion of a level whilst the moving portions (apart from most enemies with the exception of Thwomps) move faster than normal. There is not usually a time given for this comet. These comets, though similar to Fast Foe Comets, only appear in Super Mario Galaxy 2
- Grandmaster Galaxy. These comets appear all at once, and can only be unlocked once Mario has collected the previous 120 Power Stars. These comets only appear in Super Mario Galaxy 2. Green Comets are a fundamental part of Super Mario Galaxy 2, as half the stars to collect are derived from the Green Comet. Green Comets add 2-3 Green Stars to a galaxy that didn't appear before. These are not exactly new missions, more of a hide and seek game with the star. These comets appear in every galaxy in Super Mario Galaxy 2 apart from