As I stepped into the narrow bridgeroom the pilot at the controls there turned toward me, saluting.
"Alpha Centauri dead ahead, sir," he reported.
"Turn thirty degrees outward," I told him, "and throttle down to eighty light-speeds until we've passed the star."
Instantly the shining levers flicked back under his hands, and as I stepped over to his side I saw the arrows of the speed-dials creeping backward with the slowing of our flight. Then, gazing through the broad windows which formed the room's front side, I watched the interstellar panorama ahead shifting sidewise with the turning of our course.
The narrow bridgeroom lay across the very top of our ship's long, cigarlike hull, and through its windows all the brilliance of the heavens around us lay revealed. Ahead flamed the great double star of Alpha Centauri, two mighty blazing suns which dimmed all else in the heavens, and which crept slowly sidewise as we veered away from them. Toward our right there stretched along the inky skies the far-flung powdered fires of the galaxy's thronging suns, gemmed with the crimson splendors of Betelgeuse and the clear brilliance of Canopus and the hot white light of Rigel. And straight ahead, now, gleaming out beyond the twin suns we were passing, shone the clear yellow star that was the sun of our own system.
It was the yellow star that I was watching, now, as our ship fled on toward it at eighty times the speed of light; for more than two years had passed since our cruiser had left it, to become a part of that great navy of the Federation of Stars which maintained peace over all the Galaxy. We had gone far with the fleet, in those two years, cruising with it the length and breadth of the Milky Way, patrolling the space-lanes of the Galaxy and helping to crush the occasional pirate ships which appeared to levy toll on the interstellar commerce. And now that an order flashed from the authorities of our own solar system had recalled us home, it was with an unalloyed eagerness that we looked forward to the moment of our return. The stars we had touched at, the peoples of their worlds, these had been friendly enough toward us, as fellow-members of the great Federation, yet for all their hospitality we had been glad enough to leave them. For though we had long ago become accustomed to the alien and unhuman forms of the different stellar races, from the strange brain-men of Algol to the birdlike people of Sirius, their worlds were not human worlds, not the familiar eight little planets which swung around our own sun, and toward which we were speeding homeward now.
While I mused thus at the window the two circling suns of Alpha Centauri had dropped behind us, and now, with a swift clicking of switches, the pilot beside me turned on our full speed. Within a few minutes our ship was hurtling on at almost a thousand light-speeds, flung forward by the power of our newly invented de-transforming generators, which could produce propulsion-vibrations of almost a thousand times the frequency of the light-vibrations. At this immense velocity, matched by few other craft in the Galaxy, we were leaping through millions of miles of space each second, yet the gleaming yellow star ahead seemed quite unchanged in size.
Abruptly the door behind me clicked open to admit young Dal Nara, the ship's second-officer, descended from a long line of famous interstellar pilots, who grinned at me openly as she saluted.
"Twelve more hours, sir, and we'll be there," she said.
I smiled at her eagerness. "You'll not be sorry to get back to our little sun, will you?" I asked, and she shook her head.
"Not I! It may be just a pinhead beside Canopus and the rest, but there's no place like it in the Galaxy. I'm wondering, though, what made them call us back to the fleet so suddenly."
My own face clouded, at that. "I don't know," I said, slowly. "It's almost unprecedented for any star to call one of its ships back from the Federation fleet, but there must have been some reason-"
"Well," she said cheerfully, turning toward the door, "it doesn't matter what the reason is, so long as it means a trip home. The crew is worse than I am-they're scrapping the generators down in the engineroom to get another light-speed out of them."
I laughed as the door clicked shut behind her, but as I turned back to the window the question she had voiced rose again in my mind, and I gazed thoughtfully toward the yellow star ahead. For as I had told Dal Nara, it was a well-nigh unheard-of thing for any star to recall one of its cruisers from the great fleet of the Federation. Including as it did every peopled star in the Galaxy, the Federation relied entirely upon the fleet to police the interstellar spaces, and to that fleet each star contributed its quota of cruisers. Only a last extremity, I knew, would ever induce any star to recall one of its ships, yet the message flashed to our ship had ordered us to return to the solar system at full speed and report at the Bureau of Astronomical Knowledge, on Neptune. Whatever was behind the order, I thought, I would learn soon enough, for we were now speeding over the last lap of our homeward journey; so I strove to put the matter from my mind for the time being.
With an odd persistence, though, the question continued to trouble my thoughts in the hours that followed, and when we finally swept in toward the solar system twelve hours later, it was with a certain abstractedness that I watched the slow largening of the yellow star that was our sun. Our velocity had slackened steadily as we approached that star, and we were moving at a bare one light-speed when we finally swept down toward its outermost, far-swinging planet, Neptune, the solar system's point of arrival and departure for all interstellar commerce. Even this speed we reduced still further as we sped past Neptune's single circling moon and down through the crowded shipping-lanes toward the surface of the planet itself.
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 mailboats 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!
"The calculations of our scientists showed that this speeding dark star would not race into our Galaxy but would speed past its edge, and out into infinite space again, passing no closer to our own sun, at the edge, than some fifteen billion miles. There was no possibility of collision or danger from it, therefore; and so though the approach of the dark star is known to all in the solar system, there is no idea of any peril connected with it. But there is something else which has been kept quite secret from the peoples of the solar system, something known only to a few astronomers and officials. And that is that during the last few weeks the path of this speeding dark star has changed from a straight path to a curving one, that it is curving inward toward the edge of our Galaxy and will now pass our own sun, in less than twelve weeks, at a distance of less than three billion miles, instead of fifteen! And when this titanic dead sun passes that close to our own sun there can be but one result. Inevitably our own sun will be caught by the powerful gravitational grip of the giant dark star and carried out with all its planets into the depths of infinite space, never to return!"
Hurus Hol paused, his face white and set, gazing past me with wide, unseeing eyes. My brain whirling beneath the stunning revelation, I sat rigid, silent, and in a moment he went on.
"If this thing were known to all," he said slowly, "there would be an instant, terrible panic over the solar system, and for that reason only a handful have been told. Flight is impossible, for there are not enough ships in the Galaxy to transport the trillions of the solar system's population to another star in the four weeks that are left to us. There is but one chance-one blind, slender chance-and that is to turn aside this onward-thundering dark star from its present inward-curving path, to cause it to pass our sun and the Galaxy's edge far enough away to be harmless. And it is for this reason that we ordered your return.
"For it is my plan to speed out of the Galaxy into the depths of outer space to meet this approaching dark star, taking all of the scientific apparatus and equipment which might be used to swerve it aside from this curving path it is following. During the last week I have assembled the equipment for the expedition and have gathered together a force of fifty star-cruisers which are even now resting on the roof of this building, manned and ready for the trip. These are only swift mail-cruisers, though, specially equipped for the trip, and it was advisable to have at least one battle-cruiser for flag-ship of the force, and so your own was recalled from the Federation fleet. And although I shall go with the expedition, of course, it was my plan to have you yourself as its captain.
"I know, however, that you have spent the last two years in the service of the Federation fleet; so if you desire, another will be appointed to the post. It is one of danger-greater danger, I think, than any of us can dream. Yet the command is yours, if you wish to accept it."
Hurus Hol ceased, intently scanning my face. A moment I sat silent, then rose and stepped to the great open window at the room's far side. Outside stretched the greenery of gardens, and beyond them the white roofs of buildings, gleaming beneath the faint sunlight. Instinctively my eyes went up to the source of light, the tiny sun, small and faint and far, here, but still-the sun. A long moment I gazed up toward it, and then turned back to Hurus Hol. "I accept, sir," I said.
He came to his feet, his eyes shining. "I knew that you would," he said, simply, and then: "All has been ready for days, Ran Rarak. We start at once."
Ten minutes later we were on the broad roof, and the crews of our fifty ships were rushing to their posts in answer to the sharp alarm of a signal bell. Another five minutes and Hurus Hol, Dal Nara and I stood in the bridgeroom of my own cruiser, watching the white roof drop behind and beneath as we slanted up from it. In a moment the half-hundred cruisers on that roof had risen and were racing up behind us, arrowing with us toward the zenith, massed in a close, wedge-shaped formation.
Above, the brilliant signals of the traffic-boats flashed swiftly, clearing a wide lane for us, and then we had passed through the jam of traffic and were driving out past the incoming lines of interstellar ships at swiftly mounting speed, still holding the same formation with the massed cruisers behind us.
Behind and around us, now, flamed the great panorama of the Galaxy's blazing stars, but before us lay only darkness-darkness inconceivable, into which our ships were flashing out at greater and greater speed. Neptune had vanished, and far behind lay the single yellow spark that was all visible of our solar system as we fled out from it. Out-out-out-rocketing, racing on, out past the boundaries of the great Galaxy itself into the lightless void, out into the unplumbed depths of infinite space to save our threatened sun.