"The Dying Night" is a science fiction short story by Isaac Asimov. The story first appeared in the July 1956 issue of The Magazine of Fantasy & Science Fiction, and was reprinted in the collections Nine Tomorrows (1959), Asimov's Mysteries...
The imperious Winter colonists have ruled the planet Tiamat for 150 years, deriving wealth from the slaughter of the sea mers. But soon the galactic stargate will close, isolating Tiamat, and the 150-year reign of the Summer primitives will...