Shortly after Mario is invited to the centennial Star Festival by Princess Peach to celebrate the comet that passes overhead, Bowser invades the Mushroom Kingdom with a surprise attack in a fleet of airships. Summoning a giant flying saucer, Peach's entire castle is removed from its foundations and is lifted into outer space. After an unsuccessful rescue attempt, Mario is catapulted across the cosmos and awakens on a small planet. On the planet, he meets an enchantress named Rosalina and her companion stars, the Lumas. Rosalina is a watcher of the stars, who uses the Comet Observatory to travel across the universe. However, Bowser has stolen all of the Power Stars that act as the Observatory's power source, rendering it immobile. Bestowed with the power to travel through space through one of the Lumas, Mario sets off on a journey across the universe to reclaim the Power Stars and restore power to Rosalina's observatory.