Fifty miles above its surface all sight of the planet beneath was shut off by the thousands of great ships which hung in dense masses above it—that vast tangle of interstellar traffic which makes the great planet the terror of all inexperienced pilots. From horizon to horizon, it seemed, the ships crowded upon each other, drawn from every quarter of the Galaxy. Huge grain-boats from Betelgeuse, vast, palatial liners from Arcturus and Vega, ship-loads of radium ores from the worlds that circle giant Antares, long, swift mail-boats from distant Deneb—all these and myriad others swirled and circled in one great mass above the planet, dropping down one by one as the official traffic-directors flashed from their own boats the brilliant signals which allowed a lucky one to descend. And through occasional rifts in the crowded mass of ships could be glimpsed the interplanetary traffic of the lower levels, a swarm of swift little boats which darted ceaselessly back and forth on their comparatively short journeys, ferrying crowds of passengers to Jupiter and Venus and Earth, seeming like little toy-boats beside the mighty bulks of the great interstellar ships above them.
As our own cruiser drove down toward the mass of traffic, though, it cleared away from before us instantly; for the symbol of the Federation on our bows was known from Canopus to Fomalhaut, and the cruisers of its fleet were respected by all the traffic of the Galaxy. Arrowing down through this suddenly opened lane we sped smoothly down toward the planet's surface, hovering for a moment above its perplexing maze of white buildings and green gardens, and then slanting down toward the mighty flat-roofed building which housed the Bureau of Astronomical Knowledge. As we sped down toward its roof I could not but contrast the warm, sunny green panorama beneath with the icy desert which the planet had been until two hundred thousand years before, when the scientists of the solar system had devised the great heat-transmitters which catch the sun's heat near its blazing surface and fling it out as high-frequency vibrations to the receiving-apparatus on Neptune, to be transformed back into the heat which warms this world. In a moment, though, we were landing gently upon the broad roof, upon which rested scores of other shining cruisers whose crews stood outside them watching our arrival.
Five minutes later I was whirling downward through the building's interior in one of the automatic little cone-elevators, out of which I stepped into a long white corridor. An attendant was awaiting me there, and I followed him down the corridor's length to a high black door at its end, which he threw open for me, closing it behind me as I stepped inside.
It was an ivory-walled, high-ceilinged room in which I found myself, its whole farther side open to the sunlight and breezes of the green gardens beyond. At a desk across the room was sitting a short-set man with gray-streaked hair and keen, inquiring eyes, and as I entered he sprang up and came toward me.
"Ran Rarak!" he exclaimed. "You've come! For two days, now, we've been expecting you."
"We were delayed off Aldebaran, sir, by generator trouble," I replied, bowing, for I had recognized the speaker as Hurus Hol, chief of the Bureau of Astronomical Knowledge. Now, at a motion from him, I took a chair beside the desk while he resumed his own seat.
A moment he regarded me in silence, and then slowly spoke. "Ran Rarak," he said, "you must have wondered why your ship was ordered back here to the solar system. Well, it was ordered back for a reason which we dared not state in an open message, a reason which, if made public, would plunge the solar system instantly into a chaos of unutterable panic!"
He was silent again for a moment, his eyes on mine, and then went on. "You know, Ran Rarak, that the universe itself is composed of infinite depths of space in which float great clusters of suns, star-clusters which are separated from each other by billions of light-years of space. You know, too, that our own cluster of suns, which we call the Galaxy, is roughly disklike in shape, and that our own particular sun is situated at the very edge of this disk. Beyond lie only those inconceivable leagues of space which separate us from the neighboring star-clusters, or island-universes, depths of space never yet crossed by our own cruisers or by anything else of which we have record.
"But now, at last, something has crossed those abysses, is crossing them; since over three weeks ago our astronomers discovered that a gigantic dark star is approaching our Galaxy from the depths of infinite space—a titanic, dead sun which their instruments showed to be of a size incredible, since, dark and dead as it is, it is larger than the mightiest blazing suns in our own Galaxy, larger than Canopus or Antares or Betelgeuse—a dark, dead star millions of times larger than our own fiery sun—a gigantic wanderer out of some far realm of infinite space, racing toward our Galaxy at a velocity inconceivable!