Rosalina's Story

Rosalina's Storybook is a book in Super Mario Galaxy. While it is never explicitly said, it is the story of how Rosalina made it into outer space and how she became the "mother" of Lumas. In the Comet Observatory's Library, Rosalina sometimes reads from the storybook to the Lumas traveling with her. Mario/Luigi can come in to listen to the story. In all, the storybook contains nine chapters.

Yoshiaki Koizumi, director of Super Mario Galaxy, was the writer of the storybook. He wrote the script late at night when no one was around so no one would know what was in it. The next day, he told Shigeru Miyamoto about the story and presented it to him. Miyamoto was surprised that Yoshiaki wrote the script late at night with nobody around. Yoshiaki Koizumi, in Nintendo Power, mentions that he would enjoy seeing Rosalina's Storybook get published as a children's book. He also mentions that someone at Nintendo has actually made one copy of the storybook for himself.

Story
After Mario enters the library, Rosalina will begin to read the following story.

Super Mario Galaxy Trading Card description
''In the Library, Rosalina reads a story to the Lumas about how a young girl and a Luma built a spaceship to go in search of the Luma's mama. Eventually the little girl takes on a motherly role for this Luma and count-less others, much like Rosalina herself.''

Trivia

 * The starship that is mentioned many times throughout the story appears to be the Starshroom that the Lumas built with the Toads in Super Mario Galaxy. It differs, though, since it has no glass in the portholes/windows. It can be seen, moss-covered, in the extra credits sequence, after 120 Power Stars have been obtained.
 * A similar book appears in the secret ending of Super Mario Galaxy 2, but it tells about the events of that game itself.