Isaac Asimov - Nightfall (novel)

There it was, finally. All three bodies lined up in just the right way. Kalgash—Kalgash Two—Dovim!

Yes! It was possible for Kalgash Two to cause a total eclipse of Dovim when Dovim was the only sun visible in the sky.

But that configuration was an extreme rarity. Dovim had to be alone in its hemisphere and at maximum distance from Kalgash, while Kalgash Two had to be at its minimum distance. Kalgash Two’s apparent diameter would then be seven times that of Dovim. That was sufficient to hide Dovim’s light for well over half a day, so that no spot on the planet would escape the effects of Darkness. The computer showed that such a highly special circumstance was capable of occurring only once every—

Beenay gasped. He didn’t want to believe it.

He turned to Faro. The young graduate student’s round face was pale with shock.

Huskily Beenay said, “All right. I’m done, and I’ve got a number. But first you tell me yours.”

“Eclipse of Dovim by Kalgash Two, periodicity of two thousand and forty-nine years.”

“Yes,” Beenay said leadenly. “My number exactly. Once every two thousand and forty-nine years.”

He felt dizzy. The entire universe seemed to be reeling around him.

Once every two thousand and forty-nine years. The exact length of a Year of Godliness, according to the Apostles of Flame. The very same figure that was given in the Book of Revelations.

“—the suns will all disappear—”

“—the Stars will shoot flame down out of a black sky—”

He didn’t know what Stars were. But Siferra had discovered a hill on the Sagikan Peninsula where cities had been destroyed by flame with astonishing regularity, approximately every two thousand years. When she had had a chance to run exact carbon-14 tests, would the precise figure of the time between each conflagration on the Hill of Thombo turn out to be—two thousand and forty-nine years?

“—a black sky—”

Beenay stared helplessly across the room at Faro.

“When’s the next Dovim-only day due to occur?” he asked.

“In eleven months and four days,” Faro said grimly. “On the nineteenth of Theptar.”

“Yes,” Beenay said. “The same day when, Mondior 71 tells us, the sky is going to turn black and the fire of the gods is going to descend and destroy our civilization.”

“For the first time in my life,” Athor said, “I find myself praying with all my heart that my calculations are wrong. But I fear the gods have granted me no such mercy. We find ourselves inexorably swept along toward a conclusion that is terrible to contemplate.”

He looked around the room, letting his gaze rest for a moment on each of the people he had called together. Young Beenay 25, of course. Sheerin 501, from the Psychology Department. Siferra 89, the archaeologist.

By sheer force of will alone Athor fought to conceal from them the vast fatigue he felt, the sense of growing despair, the crushing impact of all that he had learned in the weeks just past. He fought to conceal all those things even from himself. Now and then lately he had found himself thinking that he had lived too long, found himself wishing that he had been allowed to go to his rest a year or two ago. But he swept such thoughts mercilessly from his mind. An iron will and unflagging strength of spirit had always been Athor’s prime characteristics. He refused now, with age making inroads on his vigor, to let those traits slip away.

To Sheerin he said, “Your field, as I understand it, is the study of Darkness?”

The plump psychologist seemed amused. “I suppose that’s one way of putting it. My doctoral thesis was on Darkness-related mental disorders. But Darkness research has been only one facet of my work. I’m interested in mass hysteria of all sorts—in the irrational responses of the human mind to overwhelming stimuli. The whole roster of human nuttiness, that’s what keeps the bread on my table.”

“Very well,” Athor said coolly. “Be that as it may. Beenay 25 says you’re the ranking authority on Darkness at the university. You’ve just seen our little astronomical demonstration on the computer screen. I assume you comprehend the essential implications of what we’ve discovered.”

The old astronomer could not find some way of preventing that from sounding patronizing. But Sheerin didn’t seem particularly offended.

Calmly he said, “I think I grasped it well enough. You’re saying that there’s a mysterious invisible planetary-sized astronomical body of such-and-such mass in orbit around Kalgash at such-and-such a distance, and what with one such-and-such and the other, its force of attraction exactly accounts for certain deviations from theory in Kalgash’s orbit that my friend Beenay here has discovered. Am I right so far?”

“Yes,” Athor said. “Quite correct.”

“Well,” Sheerin continued, “it turns out that sometimes this body would get between us and one of our suns. This is termed an eclipse. But only one sun lies in its plane of revolutions in such a way that it can ever be eclipsed, and that sun is Dovim. It has been shown that the eclipse will occur only when”—Sheerin paused, frowning,—“when Dovim is the only sun in the sky, and both it and this so-called Kalgash Two are lined up in such a way that Kalgash Two completely covers the disk of Dovim and no light at all gets through to us. Am I still doing okay?”

Athor nodded. “You’ve grasped it perfectly.”

“I was afraid of that. I was hoping I had misunderstood.”

“Now, as to the effects of the eclipse—” Athor said.

Sheerin took a deep breath. “All right. The eclipse—which happens only once every two thousand and forty-nine years, the gods be thanked!—will cause an extended period of universal Darkness on Kalgash. As the world turns, each continent will be totally dark for periods ranging from—what did you say?—nine to fourteen hours, depending on latitude.”

“Now: if you please,” Athor said, “what is your opinion, as a professional psychologist, of the effect that this will create in the minds of human beings?”

“The effect,” Sheerin said unhesitatingly, “will be madness.”

It was suddenly very quiet in the room.

At length Athor said, “Universal madness, is that what you’re predicting?”

“Very likely. Universal Darkness, universal madness. My guess is that people will be affected to varying degrees, ranging from short-range disorientation and depression to complete and permanent destruction of the reasoning powers. The greater the psychological stability one has to begin with, naturally, the less likely one is to be entirely shattered by the impact of the absence of all light. But no one, I think, will be entirely unscathed.”

“I don’t understand,” Beenay said. “What is there in Darkness to drive people mad?”

Sheerin smiled. “We simply aren’t adapted for it. Imagine, if you can, a world that has only one sun. As that world rotates on its axis, each hemisphere will receive light for half the day and will be entirely dark for the other half.”

Beenay made an involuntary gesture of horror.

“Do you see?” Sheerin cried. “You don’t even like the sound of it! But the inhabitants of that planet will be quite accustomed to a daily dose of Darkness. Very likely they’ll find the daylight hours cheerier and more to their liking, but they’ll shrug off the Darkness as an ordinary everyday event, nothing to get excited about, just something to sleep through while waiting for morning to come. Not us, though. We’ve evolved under conditions of perpetual sunlight, every hour of the day, all year round. If Onos isn’t in the sky, Tano and Sitha and Dovim are, or Patru and Trey, and so forth. Our minds, even the physiologies of our bodies, are accustomed to constant brightness. We don’t like even a brief moment without it. You sleep with a godlight on in your room, I take it?”