The Light We Carry Home by Paul Dorin

Thirteen-year-old Jonah Paxton dreams of becoming an astronaut, but a rare form of leukemia is stealing his future. Light-years away, Sirius has one last chance to fulfill his father's dying wish and become an interstellar diplomat. His orders are simple: find the right planet, find the right subject. When a mysterious orb appears in Jonah’s bedroom, capable of answering any question—but only one per day—Jonah and four other boys form a secret club. They meet nightly in a treehouse to ask impossible questions. The answers feel like gifts from outer space. But what begins as wonder soon turns into something far more profound: they're not just asking questions—they’re being judged. Secrets surface and personalities clash as their lives become intertwined in ways none of them, including Sirius, could have imagined. And the fate of humanity may hinge on what they choose to ask… and why. (Previously published as Crickets on the Moon)