A Deepness in the Sky is a science fiction novel by American writer Vernor Vinge. Published in 1999, the novel is a loose prequel 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.

Vernor Steffen Vinge was an American science fiction author and professor. He taught mathematics and computer science at San Diego State University. He was the first wide-scale popularizer of the technological singularity concept and among the first authors to present a fictional "cyberspace". He won the Hugo Award for his novels A Fire Upon the Deep (1992), A Deepness in the Sky (1999), and Rainbows End (2006), and novellas Fast Times at Fairmont High (2001) and The Cookie Monster (2004).