Super Mario Galaxy's hub world is known as the Comet Observatory. In its center is what a character describes as a "ball of flame" called the Beacon which powers the whole observatory. This beacon starts off small, but as the player collects Grand Stars, the beacon grows in size and changes color. This beacon changes color from burgundy, to orange, to yellow, green, greenish-blue, blue, and turquoise. I'm sure from this description your immediate thought is "star". However, if this beacon was really a star, the heat it would be releasing would be catastrophic for anyone nearby. Stars' gravitational pulls are powerful enough to control the movement of planets, let alone the effects it should have on Mario and the Observatory. Mario should be lucky he hasn't melted yet. Most 3d Mario games have been about collecting stars, but this is nowhere near the same thing.