The Rainbow Star is an item in Super Mario Galaxy. It is a rainbow colored star. When Mario uses it, he becomes Rainbow Mario. He becomes invincible too. Mario can run faster. If he keeps running (without stopping) Star Bits appear. If he still keeps running he spreads his arms out and has longer jumps. As it wears off, the music and Mario's running will get faster and faster... then it is over. Rainbow Stars do act like a Starman. They're probably Super Mario Galaxy's own Starman.