The ring system didn’t terminate at a sharp inner boundary, like Saturn’s. Instead the creamy, smoothed-out material stretched inwards — this system was actually more a disc than a ring system, Louise realized slowly. As her eyes tracked in toward the center the system’s texture slowly changed — becoming more rough, Louise saw, with knots of high density locked into the churning surface, orbiting through tight circles, swirling visibly.

The whole assemblage was stained crimson by scattered sunlight.

The rings were almost featureless — bland, without the complex colors and braids which characterized Saturn’s system. Louise sighed. The gravitational interaction of moons had provided Saturn’s rings with their fantastic structure. The trouble was that Jupiter’s remaining moons simply weren’t up to the job of shepherding the rings. For poor, dead Jupiter, only a single dark streak marked the orbital resonance of Callisto itself.

Now, the center of the ring-disc rose above Callisto’s sharp horizon. Louise could clearly see inhomogeneities churning around the geometric center of the disc, twisting through their crowded, tortured orbits. But the disc center itself was unspectacular — just a brighter patch, spinning with the rest of the disc. It was somehow frustrating, as if there were something missing.

Spinner sounded disappointed. “I can’t see anything in the middle. Where the planet used to be.”

Louise grinned. “You’d hardly expect to. A black hole with Jupiter’s mass would have a diameter of just twenty feet or so…”

“There’s plenty to see in higher frequencies,” Mark cut in. “The X-ray, and higher…

“Toward the heart of the system we have a true accretion disc,” he went on, “with matter being heated tremendously before falling into the black hole itself. It’s small, but there’s a lot of structure there, if you look at it in the right bands.”

Spinner, with apparent eagerness, adjusted her plate over her face, and Mark told her how to fix the settings. Soon, Spinner’s eyes assumed that unfocused look again as they adjusted to the enhanced imagery.

Louise left her own visor in her lap; the black hole, and its huge, milky ring, depressed her enough in visible light.

Jupiter’s new ring system, with its bland paleness, and the jostling, crowding swirl at the center, was far from beautiful, on any wavelength. It was too obviously a place of wreckage, of destruction — a destruction which was visibly continuing, as the black hole gnawed at its accretion disc. And, to Louise’s engineer’s eye, with its empty center the system had something of an unfinished, provisional look. There was no soul to this system, she thought, no balance to the scale of the rings: by comparison, Saturn’s rings had been an adornment, a necklace of ice and rock around the throat of an already beautiful world.

Spinner turned to her, her bespectacled eyes masked by the faceplate. “The whole thing’s like a whirlpool,” she said.

Louise shrugged. “I suppose so. A whirlpool surrounding a hole in spacetime.”

“A whirlpool of gas — ”

— gas, and rock and water ice: bits of smashed-up worlds —

Louise started to tell Spinner-of-Rope about the vanished moons of Jupiter. She remembered Io with its volcano mouths and their hundred-mile-high vents, its sulfur-stained surface and its surrounding torus of volcano-fed plasma; she remembered Io’s mineral mines, nestling in the shadow of the huge volcano Babbar Patera. She told Spinner of Ganymede: larger than Mercury, heavily cratered and geologically rich — the most stable and heavily populated of all the Jovian moons. And Europa, a ball of ice, with a bright smooth surface — constantly renewed by melting and tectonic stress — covering a liquid layer beneath. Europa had been a bright precursor of this smoothed-over corpse of Callisto, perhaps.

Worlds, all populated — all gone.

Louise hoped fervently that there had been time to evacuate the moons before the final disaster. If not, then — drifting through Jovian orbit among the fragments of rock and ice which comprised those rings — there would be bits of humanity: shards of shattered homes, children’s toys, corpses.

Spinner pushed up her faceplate and rubbed her eyes. “I’d have liked to have seen Jupiter, I think, with its moons and all those cities… Perhaps Jupiter could have been saved. After all, the implosion must have taken thousands of years, you told me.”

Louise bit back a sarcastic reply. “Yes. But picking black holes out of the heart of a gas giant was evidently a bit too difficult, even for the humans of many millennia beyond my time.”

Jupiter had been wrecked by the actions of the Friends of Wigner.

The Friends were human rebels from a Qax-occupied future, who had fled back in time through Michael Poole’s time-tunnel wormhole.

The Friends had had in mind some grand, impossible scheme to alter history. Their plan had involved firing asteroid-mass black holes into Jupiter.

The Friends’ project had been interrupted by the arrival of Qax warships through Poole’s wormhole — but not before the Friends had succeeded in spearing the giant planet with several of their tiny singularities.

The pinprick singularities had looped through the thick Jovian atmosphere like deadly insects, trailing threads of plasma. When the holes met, they had whirled around each other before coalescing, their event horizons collapsing into each other in Planck timescales.

The vibration of merging event horizons had emitted vicious pulses of gravity waves. Founts of thick, chemically complex atmosphere had been hurled out of the planet, bizarre volcanoes on a world of gas.

The Friends’ ambitions had been far-reaching. Before the final implosion they’d meant to sculpt the huge planet with these directed gravity-wave pulses, produced by the complex interactions of their singularity bullets.

Louise now stared morosely at the bland, displeasing disc of glowing rubble. Well, the Friends had certainly succeeded in part of their project — the reduction of Jupiter. Quite a monument to such ambition, after five million years, Louise thought: a collapsed Jovian, and a string of crushed human worlds.

And all for what? A black hole of the wrong size…

“It’s getting brighter over there,” Spinner said, pointing.

Louise looked right, across Callisto. A dull, flat crimson light was spreading across the ice. The glow cast long, disproportionate shadows from the low irregularities in Callisto’s smooth surface, turning the ice plain into a complex landscape of ruby-sparkling promontories and blood-red pools of shadow.

At the horizon, smoky tendrils of crimson gas were rising across the sky.

“Sunrise on Callisto,” Louise said sourly. “Come on; let’s land. We don’t want to miss the full beauty of the Solar System’s one remaining wonder, do we?”

On the surface of Callisto, standing beside Louise in her environment suit. Spinner held up her arms, framing the Sun with her outspread hands; standing there on the light-stained ice floor, with the swollen globe reflected, distorted, in her faceplate, Spinner-of-Rope looked more than ever like a child.

Sol, looming over the horizon, was a wall of blood-red smoke. It was transparent enough to see through to the distant stars for perhaps a quarter of the disc’s radius — in fact, the material was so thin that Louise could make out the steadily deepening color of the thicker layers toward the core.

The Sun didn’t even look like a star any more, she thought tiredly. A star was supposed to be hard, bright, hot; you weren’t supposed to be able to see through it.

“Another astrophysicist’s dream,” Mark said drily. “You could learn more about the nature of stellar evolution just by standing there and looking, than in all the first five millennia of human astronomy.”