Arthur Clarke: Earthlight

Sadler dropped the trenchant editorial in Time Interplanetary which he had been reading with growing annoyance. The magazine fell with that dreamlike slowness he had not yet grown accustomed to, and he followed Wagnall to the elevator.

They rose past the residential level, past Administration, past Power and Transport, and emerged into one of the small observation domes. The plastic bubble was scarcely ten meters across, and the awnings that shielded it during the lunar day had been rolled back. Wagnall switched off the internal lights, and they stood looking up at the stars and the waxing Earth. Sadler had been here several times before; he knew no better cure for mental fatigue.

A quarter of a kilometer away the great framework of the largest telescope ever built by man was pointing steadily toward a spot in the southern sky. Sadler knew that it was looking at no stars that his eyes could see—at no stars, indeed, that belonged to this universe. It would be probing the limits of space, a billion light-years from home.

Then, unexpectedly, it began to swing toward the north. Wagnall chuckled quietly.

“A lot of people will be tearing their hair now,” he said. “We’ve interrupted the program to turn the big guns on Nova Draconis. Let’s see if we can find it.”

He searched for a little while, consulting a sketch in his hand. Sadler, also staring into the north, could see nothing in the least unusual. All the stars there looked just the same to him. But presently, following Wagnall’s instructions, and using the Great Bear and Polaris as guides, he found the faint star low down in the northern sky. It was not at all impressive, even if you realized that a couple of days before only the largest telescopes could have found it, and that it had climbed in brilliance a hundred thousand times in a few hours.

Perhaps Wagnall sensed his disappointment.

“It may not look very spectacular now,” he said defensively, “but it’s still on the rise. With any luck, we may really see something in a day or two.”

Day lunar or day terrestrial? Sadler wondered. It was rather confusing, like so many things here. All the clocks ran on a twenty-four hour system and kept Greenwich Mean Time. One minor advantage of this was that one had only to glance at the Earth to get a reasonably accurate time check. But it meant that the progress of light and dark on the lunar surface had no connection at all with what the clocks might say. The sun could be anywhere above or below the horizon when the docks said it was noon.

Sadler glanced away from the north, back to the Observatory. He had always assumed—without bothering to think about it— that any observatory would consist of a cluster of giant domes, and had forgotten that here on the weatherless Moon there would be no purpose in enclosing the instruments. The thousand centimeter reflector and its smaller companion stood naked and unprotected in the vacuum of space. Only their fragile masters remained underground in the warmth and air of this buried city.

The horizon was almost flat in all directions. Though the Observatory was at the center of the great walled-plain of Plato, the mountain ring was hidden by the curve of the Moon. It was a bleak and desolate prospect, without even a few hills to give it interest. Only a dusty plain, studded here and there with blowholes and craterlets—and the enigmatic works of man, straining at the stars and trying to wrest away their secrets.

As they left, Sadler glanced once more toward Draco, but already he had forgotten which of the faint circumpolar stars was the one he had come to see. “Exactly why,” he said to Wag-nail, as tactfully as he could—for he did not want to hurt the secretary’s feelings—“is this star so important?”

Wagnall looked incredulous, then pained, then understanding.

“Well,” he began, “I guess stars are like people. The well-behaved ones never attract much attention. They teach us something, of course, but we can learn a lot more from the ones that go off the rails.”

“And do stars do that sort of thing fairly often?”

“Every year about a hundred blow up in our galaxy alone, but those are only ordinary novae. At their peak, they may be above a hundred thousand times as bright as the sun. A supernova is a very much rarer, and a very much more exciting affair. We still don’t know what causes it, but when a star goes super it may become several billion times brighter than the sun. In fact, it can outshine all the other stars in the galaxy added together.”

Sadler considered this for a while. It was certainly a thought calculated to inspire a moment’s silent reflection.

“The important thing is,” Wagnall continued eagerly, “that nothing like this has happened since telescopes were invented. The last supernova in our universe was six hundred years ago. There have been plenty in other galaxies, but they’re too far away to be studied properly. This one, as it were, is right on our doorstep. That fact will be pretty obvious in a couple of days. In a few hours it will be outshining everything in the sky, except the sun and Earth.”

“And what do you expect to learn from it?”

“A supernova explosion is the most titanic event known to occur in nature. We’ll be able to study the behavior of matter under conditions that make the middle of an atom bomb look like a dead calm. But if you’re one of those people who always want a practical use for everything, surely it’s of considerable interest to find what makes a star explode? One day, after all, our sun may decide to do likewise.”

“And in that case,” retorted Sadler, “I’d really prefer not to know about it in advance. I wonder if that nova took any planets with it?”

“There’s absolutely no way of telling. But it must happen fairly often, because at least one star in ten’s got planets.”

It was a heart-freezing thought. At any moment, as likely as not, somewhere in the universe a whole solar system, with strangely peopled worlds and civilizations, was being tossed carelessly into a cosmic furnace. Life was a fragile and delicate phenomenon, poised on the razor’s edge between cold and heat.

But Man was not content with the hazards that Nature could provide. He was busily building his own funeral pyre.

The same thought had occurred to Dr. Molton, but unlike Sadler he could set against it a more cheerful one. Nova Draco-nts was more than two thousand light-years away; the flash of the detonation had been traveling since the birth of Christ. In that time, it must have swept through millions of solar systems, have alerted the inhabitants of a thousand worlds. Even at this moment, scattered over the surface of a sphere four thousand light-years in diameter, there must surely be other astronomers, with instruments not unlike his own, who would be trapping the radiations of this dying sun as they ebbed out toward the frontiers of the universe. And it was stranger still to think that infinitely more distant observers, so far away that to them the whole galaxy was no more than a faint smudge of light, would notice some hundred million years from now that our island universe had momentarily doubled its brilliance…

Dr. Molton stood at the control desk in the softly lit chamber that was his laboratory and workshop. It had once been little different from any of the other cells that made up the Observatory, but its occupant had stamped his personality upon it. In one corner stood a vase of artificial flowers, something both incongruous and welcome in such a place as this. It was Molton’s only eccentricity, and no one grudged it to him. Since the native lunar vegetation gave such little scope for ornament, he was forced to use creations of wax and wire, skillfully made up for him in Central City. Their arrangement he varied with such ingenuity and resource that he never seemed to have the same flowers on two successive days.