A sunspot — deep black at its heart, giving an impression of a wound in the Sun’s hide, of immense depth — unfolded beneath them, ponderously.
“We seem to be traveling so slowly,” she said.
He smiled. “We’re in free orbit around the Sun. We’re actually traveling at three hundred miles a second.”
He saw her eyes widen.
He said gently, “I know. It takes a little while to get used to the scale of the Sun. It’s not a planet. If the Earth were at the center of the Sun, the whole of the Moon’s orbit would be contained within the Sun’s bulk…”
They were directly over the spot now; its central umbra was like a wound in the Sun’s glowing flesh, deep black, with the penumbra a wide, gray bruise around it. This was the largest of a small, interconnected family of spots, Scholes saw now; they looked like splashes of paint against the photosphere, and their penumbrae were linked by causeways of grayness. The spot complex passed beneath them, a landscape wrought in shades of gray.
“It’s like a tunnel,” Lieserl said. “I imagine I can see into it, right down into the heart of the Sun.”
“That’s an illusion, I’m afraid. The spot is dark only by contrast with the surrounding regions. If a major spot complex could be cut out of the Sun and left hanging in space, it would be as bright as the full Moon, seen from Earth.”
“But still, the illusion of depth is startling.”
Now the spot complex was passing beneath them, rapidly becoming foreshortened.
Scholes said uncertainly, “Of course you understand that what you see of the Sun, here, is a false-color rendering by the hull of the Lightrider. The ’Rider’s hull is actually almost perfectly reflective. Excess heat is dumped into space with high-energy lasers fixed to the hulclass="underline" the ’Rider refrigerates itself, effectively. In fact, if you could see the ship from outside it would actually be glowing more brightly than the photosphere itself…” Scholes was uncomfortably aware that he was jabbering.
“I think I follow.” She waved her claw-like hand, delicately, at the glowing surface. “But the features are real, of course. Like the spot complex.”
“Yes. Yes, of course.” Lethe, he thought suddenly. Am I patronizing her?
His brief had been to show this strange old woman the sights — to give her the VIP tour. But he knew nothing about her — it was quite possible she knew far more about the subjects he was describing than he did.
The Holy Superet Light Church was notoriously secretive: about the goals of this Solar wormhole project, and the role the old woman would play in it… although everyone knew, from the way she had been handled since arriving in near-Solar space — as if she was as fragile and precious as an eggshell — that this woman was somehow the key to the whole thing.
But how much did she know?
He watched her birdlike face carefully. The way her gray hair had been swept back into a small, hard bun made her strong-nosed face even more gaunt and threatening than it might otherwise have been.
She asked, “And is this refrigeration process how the wormhole probe is going to work — to become able to penetrate the Sun itself?”
He hesitated. “Something like it, yes. The key to refrigerating a volume is to suck heat out of the volume faster than it’s allowed in. We’ll be taking Solar heat away from the AI complex out through the wormhole, and dumping it outside the Sun itself; actually we’re planning to use that energy as a secondary power source for Thoth…”
She shifted in her chair, stiff and cautious, as if afraid of breaking something. “Dr. Scholes, tell me. Will we be leaving freefall?”
The question was surprising. He looked at her; “During this flight, in the Lightrider?”
She returned his look calmly, waiting.
“We’re actually in free orbit around the Sun; this close to the surface the period is about three hours… We’ll make a complete orbit. Then we’ll climb back out to Thoth… But we’ll proceed the whole way at low acceleration; you should barely feel a thing. Why do you ask?” He hesitated. “Are you uncomfortable?”
“No. But I would be if we started to ramp up the gees. I’m a little more fragile than I used to be, you see.” Her tone was baffling — self-deprecating, wistful, perhaps with a hint of resentment.
He nodded and turned away, unsure how to respond. “Oh, dear.” Unexpectedly, she was smiling, revealing small, yellow-gold teeth. “I’m sorry, Dr. Scholes. I suspect I’m intimidating you.”
“A little, yes.” He grinned.
“You really don’t know what to make of me, do you?”
He spread his hands. “The trouble is, frankly, I’m not sure how much you know.” He hesitated. “I don’t want to feel I’m patronizing you, by — ”
“Don’t feel that.” Unexpectedly she let her hand rest on his; her fingers felt like dried twigs, but her palm was surprisingly warm, leathery. “You’re fulfilling the request I made, for this trip, very well. Assume I know nothing; you can treat me as an empty-headed tourist.” Her smile turned into a grin, almost mischievous; suddenly she seemed much less alien, in Scholes’ eyes. “As ignorant as a visiting politician, or Superet high-up, even. Tell me about sunspots, for instance.”
He laughed. “All right… To understand that, you need to know how the Sun is put together.”
The Sun was a thing of layers, like a Chinese box.
At the Sun’s heart was an immense fusion reactor, extending across two hundred thousand miles. This core region — contained within just a quarter of the Sun’s diameter — provided nearly all the Sun’s luminosity, the energy which caused the Sun to shine.
Beyond the fusing core, the Sun consisted of a thinning plasma. Photons packets of radiation emitted from the core — worked their way through this radiative layer, on average traveling no more than an inch before bouncing off a nucleus or electron. It could take an individual photon millions of years to work its way through the crowd to the surface of the Sun.
Moving outwards from the core, the density, temperature and pressure of the plasma fell steadily, until at last — four-fifths of the way to the surface electrons could cling to nuclei to form atoms — and, unlike the bare nuclei of the plasma, the atoms were able to absorb the energy of the photons.
It was as if the photons, after struggling out from the fusing center, had hit a brick wall. All of their energy was dumped into the atoms. The gas above the wall responded — like a pan of water heated from below — by convecting, with hot material rising and dragging down cooler material from above.
The wormhole probe, with its fragile cargo, would be able to penetrate as far as the bottom of this convective zone, twenty percent of the way toward the center of the Sun.
She nodded. “And the photosphere which we see, with its granules and supergranules, is essentially the top layer of the convective zone. It’s like the surface of your pan of boiling water.”
“Yes. And it’s the properties of the material in the convective zone that cause sunspots.”
The convective zone matter was highly charged. The Sun’s magnetic field was intense, and its flux tubes, each a hundred yards across, became locked into the charged material.
The Sun’s rotation spread the frozen-in flux lines, stretching them around the Sun’s interior like bands of elastic. The tubes became tangled into ropes, disturbed by bubbles of rising gas and twisted by convection. Kinks in the tangled ropes became buoyant enough to float up to the surface and spread out, causing spots and spot groups.
She smiled as he spoke. “You know, I feel as if I’m returning to my childhood. I studied Solar physics intensely,” she said. “And a lot else, besides. I remember doing it. But…” She sighed. “I seem to retain less and less.
“The Sun is my life’s work, you see, Dr. Scholes. I’ve known that since I was born. I once knew much about the Sun. And in the future,” she went on ambiguously, “I shall once again know a great deal. More, perhaps, than anyone who has yet lived.”