Twelve-year-old Libby Monroe is great at science, being optimistic, and talking to her famous, accomplished friends (okay, maybe that last one is only in her head). She's not great at playing piano, sitting still, or figuring out how to say the right thing at the right time in real life. Libby was born with Turner Syndrome, and that makes some things hard. But she has lots of people who love her, and that makes her pretty lucky.

When her big sister Nonny tells her she's pregnant, Libby is thrilled--but worried. Nonny and her husband are in a financial black hole, and Libby knows that babies aren't always born healthy. So she strikes a deal with the universe: She'll enter a contest with a project about Cecelia Payne, the first person to discover what stars are made of. If she wins the grand prize and gives all that money to Nonny's family, then the baby will be perfect. Does she have what it takes to care for the sister that has always cared for her? And what will it take for the universe to notice?