Bowser's Star Reactor is a level located in Super Mario Galaxy and the first level where Mario fights Bowser. Before Mario fights Bowser, he has to travel through a short level that resembles one of the Bowser levels from Super Mario 64, which is also where the theme music for this level comes from. After Mario reaches a green staircase at the level's end, Bowser will appear and start breathing fiery rocks at the staircase. This causes the stairs to start breaking; Mario must reach the top before they break completely. Upon reaching the top, Bowser roars and changes the gravity; Mario and Bowser fall to a metallic planet above the level. Mario fights Bowser on this planet. After he defeats Bowser, the King of the Koopas says he has not been defeated yet, teleports away, and leaves a Grand