Nightfall

On the planet Lagash, which orbits one of the stars of a six-star system, night comes only once every 2049 years—when five of the six lights are on one side of the planet, and the sixth is blocked from view by the moon’s shadow the size of half the planet. In a single night, the civilization perishes because everyone goes mad. But what causes the universal madness?
The astronomers of Lagash, who observe the six stars of their system, do not know what the rest of the universe is like (they don’t even know about the moon). They cannot warn the people about what awaits them. And the answer comes from the fact that the Lagash system is part of a giant star cluster consisting of 30,000 rather close and large stars—turning the expected night into a bright and terrifying “day.”

The story not only confirms the well-known truth that “knowledge is power,” but adds an important warning: ignorance is death.