“I still don’t understand,” Siobhan said. “Why would these Firstborn of yours want to put us under threat of extinction?”
Bisesa shook her head. “I know the Firstborn better than anybody else, I guess. But I can’t answer that. One thing I’m sure about, though. They watch.”
“Watch?”
“I think that’s what Mir was all about. Mir was a montage of all our history, right up to the moment of this—our possible destruction. Mir wasn’t about us but about the Firstborn. They forced themselves to look at what they were destroying, to face what they had done.”
She spoke hesitantly, obviously unsure of her thinking. Siobhan imagined her sitting alone for long hours, obsessively exploring her memories and her own uncertain feelings.
Bisesa went on, “They don’t want anything we know, or can make. They aren’t interested in our science or our art—otherwise they would be saving our books, our paintings, even some of us. Our stuff is far beneath them. What they do want—I think—is to know how it feels to be us, to be human. And how it feels even as we’re put to the fire.”
“So they value consciousness,” Siobhan mused. “I can see why an advanced civilization would prize mind above all other things. Perhaps it is rare in this universe of ours. They prize it, even as they destroy it. So they have ethics. Maybe they are guilty about what they’re doing.”
Bisesa laughed bitterly. “But they’re doing it even so. Which doesn’t make sense, does it? Can gods be insane?”
Siobhan glanced out at the gaunt shadows of the Dome. “Perhaps there’s a logic, even in all this destruction.”
“Do you believe that?”
Siobhan grinned. “Even if I did, I’d reject it. The hell with them.”
Bisesa answered with a fierce grin of her own. “Yes,” she said. “The hell with them.”
29: Impact
The rogue planet flew out of the sky’s equator.
While light flashed from Altair to Sol in sixteen years, the wandering planet had taken a millennium to complete its interstellar journey. Even so it approached the sun at some five thousand kilometers per second, many times the sun’s own escape velocity: it was the fastest major object ever to have crossed the solar system. As it fell toward the sun’s warmth, the Jovian’s atmosphere was battered by immense storms, and trillions of tonnes of air were stripped away, to trail behind the falling world like the tail of an immense comet.
On Earth, it was the year 4
If the rogue had come in the twenty-first century, humanity’s Spaceguard program would have spotted it. Spaceguard had its origins in a twentieth-century NASA program designed to survey all the major comets and asteroids following orbits that might bring them into a collision with the Earth. The organization’s scientists had debated many ways to deflect an incoming threat, including solar sails or nuclear weapons. But while such methods might have worked on a flying-mountain asteroid, there would have been nothing to be done about a mass this size.
In 4 , of course, there was no Spaceguard. The ancient world had known lenses since the great days of the Greeks, but it had not yet occurred to anybody to put two of them together into a telescope. But there were those who watched the sky, for in its intricate weavings of light they thought they glimpsed the thoughts of God.
In April of that year, across Europe, North Africa, and the Middle East, a great new light approached the sun. To the astrologers and astronomers, who knew every naked-eye object in the sky far better than most of their descendants of the twenty-first century, the Jovian was a glaring anomaly, and a source of fascination and fear.
Three scholars in particular watched it in awe. They called themselves magi, or magoi, which means “astrologers”—stargazers. And in the Jovian’s final days, as it neared the sun and became a morning star of ever more brilliant beauty, they followed it.
The planet battered its way through the sun’s wispy outer atmosphere, the corona. Now the star itself lay before it, unprotected.
The Jovian was a planet a fifth the diameter of the sun itself. Even at such speeds, a collision between two such immense bodies was stately. It took a full minute for the whole planet to sink into the body of the star.
In normal times the sun’s surface is a delicate tapestry of granules, the upper surfaces of huge convection cells with roots in the sun’s deep interior. When the Jovian hit, that complex hierarchical structure was disturbed, as if a baseball had been thrown into a pan of boiling water. Immense waves washed away from the point of impact and rolled around the curvature of the star.
Meanwhile the planet itself was immersed in a bath of intense heat. Through direct collisions between the sun’s plasma and the planet’s atmosphere, the sun’s energy poured into this outrageous invader. In response, the planet desperately tried to shed heat by losing its own substance. The upper layers of its air, mostly hydrogen and helium, were soon stripped off, exposing the inner layers, exotic high-pressure liquid and solid forms of hydrogen, which in turn boiled away. It was exactly as Apollo capsules had once entered Earth’s atmosphere behind ablative shields, allowing bits of the disintegrating spacecraft to carry away the heat of friction. For the Jovian the strategy worked for a while. The planet had entered the sun with the mass of fifteen Jupiters, and had the capacity to soak up a lot of heat before it was done.
Deeper and deeper the Jovian sank, through the sun’s roiling convective layer, and then into the denser, static radiative layer beneath. It was like a driving fist, and it left behind a tunnel drilled brutally through the sun’s strata, a flaw that would take millennia to heal.
By the time the Jovian reached the edge of the sun’s fusing core, it was reduced to a knot of its densest, hardest stuff—and yet it still retained a mass many times that of Jupiter. Here the last of the Jovian’s mass was broken up and dispersed—but not before it struck the core of the sun a mighty blow. There was a vast fusion surge, like an immense bomb going off at the edge of this natural reactor. That great impulse sent shock fronts pushing deep into the fusing core.
As Eugene Mangles would understand, the core was temperamental, its rate of fusion highly sensitive to changes in temperature. The Jovian was gone, but its impact had created a pattern of energetic oscillations in the core that would persist for millennia.
Meanwhile on the surface, though the planet had disappeared into the sun’s maw, the point of impact was a place of roiling turmoil.
On its way into the heart of the star, the Jovian had torn through a sensitive boundary called the tacholine: the boundary between convective and radiative zones. The dull sea of the radiative zone rotates with the sun’s core, almost as a rigid body. But the convective zone’s motion is much more complex; different parts of the sun’s surface can actually be seen to rotate at different speeds. So, at the tacholine, there is friction: the convective material moves over the radiative like a tremendous wind.
The sun is laced by a powerful magnetic field. Its interior is full of “flux tubes,” currents of magnetic energy that flow through the plasma sea. At the tacholine the differing rotations of the sun’s layers stretch the flux tubes around the sun’s equator. Mostly the churning convection above keeps them in their place. But sometimes a kink will develop in a sun-girdling rope, and it will force its way up toward the surface of the sun, dragging plasma flows with it. This is the sequence of events that leads to the “active regions” that give rise to flares and mass ejections.