Luma's story begins when he was separated from his mother. He found young Rosalina and asked her to help him find his mama. Rosalina repaired a rusty, old ship and together, she and Luma began a long search for his mom. One day they found a comet which Luma said his mother traveled on. However there was no sign of Luma's mother. Rosalina and Luma finally gave up hope of finding Luma's mother. However, Rosalina soon discovered that buried in the comet are tools and building material. Together, the duo built a small settlement. After it was completed, the building seemed rather big for just two people. Not long after, another Luma appeared traveling on a comet. Luma and the newcomer fought over Rosalina's love. More and more Lumas flew out of the comet shouting "My mama" at Rosalina. Rosalina adopted all the Lumas and became their mother. One night Luma found Rosalina crying and comforted her, asking her why she was crying. Rosalina told Luma that her mother is dead and even though she knew, she refused to believe it until then. Rosalina thanked Luma and the two hugged each other.
Later on, Luma transformed into the Comet Observatory to provide a new home for the Lumas and Rosalina. However, he was re-born and nurtured and cared for by Rosalina until he became a full grown Luma again.
 Super Mario Galaxy
Sometime later, Princess Peach found Luma and planned to give him as a present to Mario. However, just as Mario was arriving, Bowser kidnapped Peach by hoisting her castle into space. Luma escapes to a nearby planet in the Gateway Galaxy. Meanwhile, Mario is attacked by Kamek and sent to the Luma's hiding spot. Luma and his friends convince Mario to play a game of hide-and-go-seek with them. When Mario finds them Rosalina appears and tells Mario that in order to save Princess Peach, the now broken Comet Observatory needs to be fixed using Grand Stars so it can fly to where Bowser is keeping Peach. She also tells him that he will need the power to travel through space, and that Luma can give him this power. Luma decides to help Mario and, making himself at home under Mario's cap, bestowed upon Mario the power of Spinning. The two subsequently begin the hunt for the Grand Stars. Traveling from galaxy to galaxy, the two track down the Grand stars and slowly, the Comet Observatory becomes more powerful.
When the last Star is recovered, the Comet Observatory flies to the center of the universe where Bowser has created a huge star. After a final duel, Mario and Luma defeat Bowser, destroy the star, and rescue Princess Peach. However, Bowser's dying star creates a huge black hole and all the Lumas including Luma fly into it to stop it. Before being destroyed, Luma waves sadly goodbye to Mario and then dives. It is revealed, however Luma has been reborn, as all Lumas do, on another planet, and is waiting for Mario's return. In the final cutscene of the game, Luma can be seen in his and Rosalina's Starshroom, waving at the camera and then flying upward.
 Super Mario Galaxy 2
Luma makes his second appearance in Super Mario Galaxy 2, where he is called Baby Luma. He is found in the Prologue of the game lying on the ground and immediately takes a shine to Mario. Baby Luma flies into Mario's hat and Mario's body begins to tingle, giving him the power to spin. Mario later meets two other yellow Lumas which call Baby Luma "young master Luma" and send Mario off to the Sky Station Galaxy.
After Bowser is defeated, Mario returns to Starship Mario with Princess Peach and the Grand Star, after which Rosalina appears in her Comet Observatory. She explains to Mario that she knew all along that she would someday be reunited with the Baby Luma, because there is a power even beyond that of the stars that governs the destiny of them all. After promising that he'll never ever forget about Mario and taking Mario's cap as a souvenir, the Baby Luma rejoins Rosalina and leaves with her.
 Super Mario Galaxy Trading Card Description
There are no other Lumas in the Galaxy that are like the very special Apricot Luma. This is the Luma that Rosalina gives to Mario in the beginning of the game, who grants Mario the power to do star spins- a move that will be invaluable against many unforeseen enimies.
 Names in other Languages