A Deepness in the Sky is a science fiction novel by American writer 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. Background The plot begins with the discovery of an intelligent alien species on a planet orbiting an anomalous star, dubbed OnOff because for 215 of every 250 years it is dormant, releasing almost no detectable energy. During this period, the planet freezes and its fauna go into hibernation. The planet's inhabitants, called "Spiders" by the humans for their resemblance to arachnids, have reached a stage of technological development very similar to that of Earth's humans in the early 20th century, although humans believe that they may once have been capable of space travel. If this is true, then whoever can establish ties with the aliens first could reap unimaginable rewards; humans have made contact with only one other intelligent (but non-technological) alien species in millennia of travel through the stars. Two human groups launch expeditions to the Spider world: the Qeng Ho (pronounced Chung Ho and named after the explorer Zheng He), traders who have developed a common interstellar culture for humanity; and the Emergents, a civilization that literally enslaves selected human minds and has only recently re-emerged from a Dark Age. Plot summary The Qeng Ho arrive at the OnOff star shortly before the Emergent fleet, a few years before the sun turns on, at which point the Spider civilization will "wake up" and continue its climb into a technological civilization. A reception held by the Emergents doubles as a vector to infect the Qeng Ho with a timed "mindrot" virus. The Emergents time an ambush to take advantage of the onset of symptoms. During these events, a concurrent history of the Spider civilization unfolds – mainly through the picaresque, and then increasingly political and technocratic, experiences of a small group of liberal-minded and progressive Spiders. Their struggles against ignorance and obsolescent traditions are coloured with oddly human-like descriptions and nomenclature, prefiguring some major plot revelations towards the end of the story. Far above, after a close fight, the Emergents subjugate the Qeng Ho; but losses to both sides force