“Take a good look at it,” said Gilby at last. His lecture was continuing, but his voice had a different tone. “That was the only home of your ancestors for fifteen thousand years — three times as long as we’ve lived on Pentecost. The Ship roamed from system to system, never finding anywhere that could be a new home. It visited forty-nine suns and a hundred planets, and everywhere it was frozen, dead worlds, or burning deserts. Cass was the fiftieth system, and they found Pentecost. It was right to support human life. Paradise, eh? Do you know what happened then?”

They all remained silent, overwhelmed by the swelling presence of The Ship as it filled the screen in front of them.

“They argued,” said Gilby. He paused in his fidgeting with his shoulder strap to touch his gunbelt. “They squabbled in The Ship, over whether or not they should leave it and land on Pentecost. The Ship was home, and half the people didn’t want to leave. It took two hundred years before the last transfer down took place and The Ship was left deserted. The final act was to move it to a high orbit, where it could circle Pentecost forever.”

They had approached within a couple of kilometers, and were spiralling slowly around the shining hull. There was a burred, matte finish to the surface, the evidence of eons of meteor impact and the scouring of interstellar dust. “Any chance we can all go on board?” asked Wilmer. Like a small child, he had pressed his nose to the transparent port.

Gilby smiled. “It’s a shrine. No visitors allowed. The original travellers stated only one situation in which The Ship could be opened up to use again. It’s not one we care to think about. The Ship will be reopened and refurbished if nuclear weapons are ever used on Pentecost.”

He pointed to the port. “Look out there now, and fix it in your memories. You won’t see this again.”

As he spoke they felt a steadily increasing acceleration pressing them back into the seats. The Ship moved past their spacecraft, fell behind, and dwindled rapidly in size. They were heading farther out, out to the sprawling menagerie of planets that moved around and beyond Cassay and together made up the Fifty Worlds.

Seen through the best Earth telescopes, the system of Eta Cassiopeiae had been no more than twin points of light. It appeared as a striking red-and-gold binary, a glittering topaz-and-garnet jewel less than twenty light-years away from Sol. No amount of magnification by Earth observers could give any structural detail of the stellar components. But to the multiple sensors of Eleanora, curving on a slowing trajectory toward the brighter component of Cassiopeia-A, a system of bewildering complexity had revealed itself. Cassiopeia-A is a yellow-gold star, stellar type GO V. It is a little brighter and more massive than Sol. Its companion is a red dwarf, lighter and only one twenty-fifth as luminous.

Dense, rust-red, and metal-poor, Cassiopeia-B keeps its distance from the bright partner. It never approaches closer than ten billion kilometers. Seen from the planets near Cass-A, the weak, rusted cinder of the companion appears far too feeble to have any influence. But the gravitational field is a long-range force. Gravitational effects of Cass-B had profound influence on the whole system. The planetary family that evolved around Eta Cassiopeiae is a whole zoo, with a bewildering variety of specimens.

Over fifty worlds reel and gyrate around the star pair. Their orbits are at all inclinations and eccentricities. The planets within a few hundred million kilometers of Cass-A exhibit orbital regularity and stable cycles, with well-defined orbital periods and near-circular orbits. But the outer worlds show no such uniformity. Some follow paths with both Cass-A and Cass-B as foci, and their years can last for many Earth centuries. Others, locked into resonances with both primaries, weave complicated curves through space, never repeating the pattern. Sometimes they will journey in lonely isolation, billions of kilometers from either star; sometimes they dip in close to the searing surface of Cass-A. The travellers on Eleanora had concluded that a close encounter of a major planet was also the cause of the system’s complexity. Millions of years earlier, a gas giant had come too close. It had skirted the very photosphere of Cass-A. First the volatile gases were evaporated away; then irresistible tidal forces caused disruption of the remaining core. The ejecta from that disintegration had been hurled in all directions, to become parts of the Fifty Worlds. To the visitors approaching the system, the wild variations of the outer worlds at first seemed to dominate everything. The Cassiopeia binary complex was an unlikely candidate for human attention. Where orbits are wildly varying, life has no chance to develop. Changes are too extreme. Temperatures melt tin, then solidify nitrogen. If it is once established, life is persistent; it can adapt to many extremes. But there is a fragility in the original creation that calls for a long period of tightly-controlled variations.

The automated probes were sent out from Eleanora, but only because that was the procedure followed for many centuries. First returns confirmed an impression of scarred and barren worlds, bleak and empty of life. When the electronic reports were beamed back from the probe to Pentecost, they seemed just too good to be true. Here was a stable planetary orbit, close to circular, one hundred and ninety million kilometers from Cass-A. And Pentecost was a real Earth-analog, with native vegetation and animal life, acceptable temperatures, an eighteen degree axial tilt, twenty-two hour day, breathable atmosphere, forty percent ocean cover, a mass that was only ten percent less than Earth, and an orbital period only four percent longer than an Earth year.

It was hard to believe that Pentecost could exist amid the dizzying variations that comprised the Fifty Worlds. But the probes never lied. At last, after eons of travel between the stars, and endless disappointment, humanity had found a new home.

The Fifty Worlds held enormous diversity. Peron knew that. They were of all sizes, shapes, orbits, and environments. No two seemed even remotely alike, not even the twins of the doublet planet of Sambella. And most of them fit poorly anyone’s idea of a desirable place to visit, still less as the site for another trial.

And as for Whirlygig…

Peron was approaching it now. He had to land there. Of all of the worlds, he thought gloomily, this one has to be the most alien and baffling. In the past two months the Planetfest winners had orbited over a dozen worlds. The planets ranged from depressing to unspeakable. Barchan was a baking, swirling dust-ball, its surface forever invisible behind a scouring screen of wind-borne particles. They were held aloft by a thin, poisonous atmosphere. Gilby had warned them that Barchan would be a terrible choice for a trial (but he had said that about most places!). The dust and sand found its way into everything — including a ship’s controls. There was a good chance that a landing on Barchan might be final.

Gimperstand was no better. The contestants had voted not even to look at it, after one of the ship’s crew had produced a sample bottle of sap from Stinker’s juicy vines. The bottle had been opened for less than two minutes. A full day later the air through the whole ship still tasted like rotting corpses. Air purifier units didn’t even touch it.

From a distance, Glug had looked pretty good. The ship’s telescopes and scanners showed a green, fertile world, ninety percent cloud covered. They had actually made a field trip down there, and spent a couple of hours squelching and sticking on the viscous surface. A steady gray rain drifted endlessly down from an ash-dark sky, and the sodden fronds of vegetation all drooped mournfully to touch the gluey soil. Once a boot had been placed firmly, the planet acted as though reluctant ever to release it. It clung lovingly. Walking was a pained sequence of sucking, glutinous steps, dragging the foot upward inch by inch until it came free with a disgusting gurgle. As Wilmer had put it, once you had pulled your boot out you never wanted to put it back again — except that your other boot was steadily sinking in deeper.