Those that survive and recover their sanity-Beenay, Siferra, Theremon-realize that the oddly calm, decidedly pragmatic Folimun (all along, he's actually been trying to help) represents the only hope for civilization's rebirth. The eclipse duly occurs, the stars come out, Kalgash goes mad, and civilization falls in flames.

Mysterious Folimun 66 of the fanatical Apostles of Flame warns everyone to repent-though he possesses curiously precise knowledge of the catastrophe to come. Skeptical journalist Theremon 762 scoffs at the whole idea of darkness and stars and the fall of civilization. Ice maiden archeologist Siferra 89 confirms that civilization crashes and burns every 2,049 years. Eager astronomer Beenay 25 deduces the existence of an unseen planet and predicts that it will cause an eclipse. Hump psychologist Sheerin 501 (but what are the numbers for?) discovers how easily the people of planet Kalgash are driven mad by darkness. The story's essentially the same, notwithstanding the changed details and added aftermath. Here, then, 49 years later, for reasons best known to the authors, is the novel version. It is Asimov's best known and most popular story, and one of the most famous in all science fiction. Darkness falls, the stars come out the inhabitants, who have never known darkness and have never seen the stars, go mad and destroy their civilization. Periodically, only one sun of the six hangs in the sky, sad, every two thousand years, this is blotted out by an eclipse.

Asimov's long story 'Nightfall' (1941), written when he was just 21, concerns the inhabitants of a planet with six suns.

Nightfall book asimov