A Deepness in the Sky is a science fiction novel by Vernor Vinge. Published in 1999, the novel is a loose prequel (set twenty thousand years earlier) to his earlier novel A Fire Upon the Deep (1992). The title is coined by one of the story’s main characters in a debate, in a reference to the hibernating habits of his species and to the vastness of space.

Nebula Award nominee, 1999; Hugo, Campbell, and Prometheus Awards winner, 2000; Clarke and Locus SF Awards nominee, 2000.