If the sun were a solid ball—or only partially liquid, like the inner planets with their molten cores—then the field lines would be trapped immovably in the matrix of iron and stone. But the sun is not solid; its plasma is more liquid than water, more volatile than burning oil or methane.
Rotation in a solid ball, like the little green world, imparts a wrenching differential velocity that the surface structure must endure. The poles will seem not to turn at all, while the equator spins at a thousand miles an hour. In between, the basaltic land masses of the crust must shift and bend to accommodate the resulting stresses.
But in a globe of gas or plasma, where nothing is more solid than two charged particles rubbing past each other in the suspension of magnetic repulsion, those stresses wrench upon nothing. Each square kilometer of surface finds its own speed, and the atmosphere flows into banded patterns, like the faces of Jupiter and Saturn. Even on the little green world, the mantling shell of gas lapses into wide belts of alternately moving and stagnant air called "trade winds" and the "horse latitudes."
The sun's visible surface might also settle itself into such a stationary display, were it not for the fusion fires burning deep in the core, and for the intervening layers of opaque plasma that bubble and rush to carry the heat outward to the surface. The convective zone's rising columns of heated gas creates dense clots of material. Up near the poles, the ions in these rising heat cells can become aligned to the prevailing magnetic flux, trapped in the cells' electrically charged material, frozen in place inside a columnar granule of upwelling gas.
So, instead of passing through the slippery plasma like a navigational buoy anchored against the flooding tide, the field line is bent at the core and dragged off with the sphere's differential rotation, heading out into the fester-moving currents like that same buoy when its anchor chain has been cut.
Drift
Spin
Drift
Spin
When the field lines become strongly trapped in a convection cell and are ripped away from the great parent loops up near the poles, moving down into quadrants that are spinning more quickly, then the orphans tend to spin around each other, acquiring perturbations that stretch and twist their magnetic domains and break up their uniform polarity. In retaliation, seeking a new equilibrium, the broken lines curve over and plunge back into the photosphere. They create a new north or south polar charge to complement the distant place they can no longer reach, half a globe and more away.
So a trapped field line becomes a tiny loop, a horseshoe of potential, rising out of one convection cell and plunging back into another nearby. The opposing charges at the exit and entry points attract each other, and so the pair of anchor points stays together in the roiling convective layer.
Now, pulling a field line away from the pole is the usual, or probabilistic, way that a magnetic anomaly can form on the sun's surface and start to grow. There are, however, alternate methods of generation.
For example, when that thermal bloom collapsed a broad, twenty-two-degree area of convection cells near the equator, the resulting weakness in the outer layers offered a temporary shortcut to the solar magnetic field. The force lines bent and redirected themselves out through the electrically quiet patch, truncating one or more of the great loops that stretch from pole to pole.
A suddenly active region like this does not form smoothly, nor does it create a uniform magnetic charge. So close to the equator, equidistant from the two poles, the sun's magnetic domains enter a war for dominance there. Alternating divots of north and south field strength attract and link to each other. Parallel turfs with similar charges repel and isolate each other. So, once again, separate loops and horseshoes of potential form and dance around each other in the sun's outer layers.
Twist
Twine
Twist
Twine
As the short, horseshoe-curved field lines twist and stretch, buffeted by their movement through areas of more stable plasma, they gain new energy from their kinetic motion. They twist and curl around opposing columns of charged particles. The violent winding-up of these ion tubes works like an electric dynamo, inducing a strong current and strengthening the magnetic flux. The fields associated with a naturally occurring anomaly can reach 2,000 to 3,000 gauss, or a thousand times the Earth's own field. The fields over a major blowout patch can exceed ten or twenty times that strength.
A mammoth potential current flows through the horseshoe loop, induced by the furiously curling gases. The already strong and strengthening magnetic field trapped in these anchoring tubules repels the surrounding solar material; so they rise toward the sun's surface, the photosphere. And where their trapped fields touch the surface, they create quiet, dense, cool pools of matter, isolated by their high field strength from the heated gas that is continually rising around them.
These pools develop and darken long after that initial bubble of core-overload energy has escaped through the photosphere and poured itself upward into the corona. The depleted column, with nothing but magnetic charge to sustain and shape it, lies passively on the sun's face and moves with the star's rotation around the equator.
To see these pools from the outside, against the background of the photosphere, they are so cold as to appear black. The surrounding material, repelled by their charges, is slightly warmer but still not as hot as the rest of the photosphere. So this apron appears as a shadowed gray.
For half a millennium, Earthly astronomers with the means to look beyond and through the sun's glare called such dense shadows "umbra," and the gray shadings "penumbra." Darkness and near-darkness. Sunspots and their surrounding blush of cool death.
The spots, whether drifting down from the poles or arising out of the equator, appeared irregularly on the face of the sun. They came in staggered cycles, like an outbreak of plague, like rashes and buboes on the face of the daystar. So early astronomers thought of them as a sickness, as signals of catastrophe. The blemishes were considered portents of dissolution and disruption. For, after all, the things of heaven—and was not the sun the brightest and most necessary of the objects sighted beyond Earth?—were all known to be pure and unchanging. Spots on the sun could bode no good to anyone.
Reinforcing this provincial and time-limited viewpoint was the uncertainty of the solar outbreak. For reasons not clearly understood then, the black spots arose, grew in number, peaked, and fell away in cycles of eleven Earthly years. In between these cycles the sun, as humans could observe it, wore a blank, white face of perfect health. Then the sickness spots would pop out again or drift down from the sun's clear brow.
But sometimes the spots did not come at all. For year after year, decade after decade, the sun showed its clear face. And then people breathed more easily, hoping that the daystar had finally settled down to a regular, healthy life. That the plague had passed at last.
Strangely, although the sunspots themselves seemed to be dark pores and cooler pools on the burning face, they appeared to make the star burn more brightly, like fever in a plague victim. And when the spots went away, the sun's thermal output declined. On Earth, the rivers froze where before they had run all winter long. Glaciers oozed down from the snows of the mountaintops.
These effects spanned periods longer than most single human lifetimes. So, only when one man wrote down what he observed one morning and one winter, and when another man years later read those notes and compared them with this morning and this winter, could any person on the green world appreciate that a greater cycle was afoot.
But when the sunspots went away for so long, then most people stopped caring. They took no notice of what was not there. All but the astronomers themselves would grow forgetful, being preoccupied with other wonders, other problems. The world slumbered, shivered in its bed, but slumbered on.
Chapter 5
Prophet Without Honor
Tick!
Creak!
Groan!
Click!
Aboard the Solar Res
earch Vessel Hyperion, March 7, 2081
The ship's thermal management systems hummed and whirred while her silvered metal skin alternately crept and shrank, passing through and settling into fleeting new configurations as she transited the solar disk.
With each kilometer of advance in Hyperion's orbit, the superstructure's blunt end exposed micrometrically now more, now less of its face to the white blaze of energy. The circulating systems pumped their freon gel now faster, now slower to carry the excess heat backward and outward to the radiating tendrils of the heat exchangers. And there, in the tenuous shadow of the ship's mushroom cap, they conducted an unbalanced trade of warmth for warmth and so maintained the margin of coolness that supported two human lives.
Dr. Hannibal Freede barely noticed these tiny sounds, in part because he had lived with them for more than one hundred and eighty days. That was just over two solar years at approximately the same distance from the sun as the planet Mercury—except, of course, that Hyperion's orbit was polar instead of equatorial. And in part Freede ignored the stressful workings of his ship because his full attention was now glued to the monitor screen in front of him.
There the sun's image, filtered by his equipment to the narrow spectrum of hydrogen-alpha radiation, resembled the fiery mask that the Wizard of Oz had shown Dorothy and her friends on their first audience in the Emerald City. In the classic film of that story, Freede remembered, the wizard's head had been a great ball of cotton saturated with naphtha—or was it plain kerosene?—and set afire. The face had burned with little jets and gobbets of yellow flame licking upward in a smooth curve around the ball, darkening at the edges where the smoke gathered and rushed toward the ceiling. Those flames were not unlike the spicules of false fire which Freede could see on the disk that hung above Hyperion.
His eyes traveled up the screen, toward the blurred edge that was continuously passing beyond Hyperion's singular point of view. This edge was similarly darkened—but not by smoke. His straight-on view of the surface area immediately below the ship had probed more deeply into the solar atmosphere than this slantwise line of sight toward the globe's limb. The deeper one looked into the thermally stratified layers of that atmosphere, the brighter the observing field appeared. Now the area he was trying to inspect at the far edge of the sun was limited to the higher, cooler, and therefore much darker regions of the photosphere. Too dark to show clearly what he wanted to see.
Still, Freede searched in this area for any last signs of the anomaly he had faintly detected yesterday and had been tracking continuously since then. In the altered, hydrogen-alpha image, his eyes strained to see between the tips of those dancing spicules which further fuzzed up the darkening limb.
For an instant Freede could almost believe he discerned there a pattern of black scoops or crevasses. That high up on the solar disk, the clefts would certainly be foreshortened and flattened by the Wilson Effect, a trick of perspective described more than three hundred years earlier by the Scottish astronomer Alexander Wilson. The man had thereby demonstrated how the recurring dark marks on the sun's surface actually had depth and might indeed be holes in the photosphere. Viewed practically edge-on, they would probably look like the curving smear of thin, gray-edged streaks Freede had seen yesterday. He strained now to find those same, broad smudges of cool shadow.
The anomaly had certainly been strange: a horizontal clouding-up of the disk's edge, deeper and blacker than normal limb darkening, and wider by far than any penumbra he'd ever seen in the record tapes. Twenty-two degrees wide it was, according to yesterday's measurements. And then today, nothing....Or maybe the smudges were never there to begin with.
But wait a minute now! How far, after all, had Hyperion traveled down the sun's face in the last twenty-four hours? Enough to carry those shadows over the horizon?
He checked with the computer: since the first sighting yesterday, Hyperion had moved four-point-two million kilometers farther toward the south pole, which would soon pass immediately below him. And the anomaly had been much higher up, almost on the equator. Thus the distance his ship had traveled south, coupled with the sun's own rotation in its twenty-seven-day period, would certainly have shifted whatever it was he thought he'd seen to the north and west—out of his line of sight by now.
Freede next tried to correlate that lost visual sighting with Hyperion's ongoing magnetometric survey of the sun's surface layers. He studied the pattern of gauss readings that was displayed on another screen, taken from instruments extended on long booms beyond the magnetic interference of his own hull. But results here were inconclusive. Of course, the ship's magnetometers would now be reading the incredibly strong field flux at the south pole. Any disturbance along a slant line toward the equator was certainly lost in that whorl. And then again, maybe he had seen nothing at all.
All of this was damnably frustrating.
It was to study just such anomalies in the solar surface that Freede had built his ship. He had done it practically out of his own pocket, too, taking seed money from his family trust and supplementing it with meager donations from a patchwork of corporate and charitable endowments. Hyperion had been constructed to his own specifications at one of the lunar Lagrange points and launched on a time-consuming but economical orbit to achieve her own capture on the lip of the sun's immense gravity well.
Hyperion's crew consisted of Freede himself as captain, with his wife Angelika as first officer, backup helmsman, second astronomical observer, chief engineer and systems technician, quartermaster general, cook and bottlewasher, and companion. Their mission profile called for at least ten revolutions about the sun—with two of them now gone. That amount of time, as Freede had planned so many years ago, should allow him to take definitive readings and draw his own conclusions about the elusive nature of the sun's variable activity.
For example, take this smudge or crevasse or whatever it was he thought he had seen, just now disappearing around the limb. Maybe there were more of them growing on the backside of the sphere, hidden from Freede and his equipment. In his currently reduced financial circumstances, able to afford just one observing platform, he could only look at one side of the solar globe at a time. What he needed, of course, was to set up a chain of orbiting observation satellites, communicating with Hyperion by means of signal relays. But such extended facilities were well out of his reach.
A family fortune! The amounts had sounded so immense in the mouths of Freede's attorneys. And the annuities were large—until you tried to do something worthwhile with them, like mount a private astronomical expedition. Then the bills piled up and the cashflows drained away.
Even bringing Angelika and himself home would be a chancy maneuver. First, they would dislodge Hyperion from her stable, minimally elliptical solar orbit, sending the vessel into a looping, cometary flight path out beyond the orbit of Venus, three-quarters of the way to the sphere of the Earth-Moon system. Next, as Freede had arranged with the family's lawyers, a fast-moving probe would be launched on a date and trajectory that would cause it to rendezvous with Hyperion, take off her two-person crew and their record of observations, loop back around the star at far greater speeds, and deposit them out in the sunjammer lanes somewhere in the vicinity of Jupiter. Then Freede would put up a distress beacon and claim refuge aboard the first passing freighter, manned or automated, under the international rules governing maroon and salvage.
That the ending of a prestigious scientific mission must employ a radical and, to put it bluntly, ungentlemanly device was regrettable. But it did fit the size of Freede's purse and the magnitude of the masses and motions involved. And was not all fair in the quest for scientific understanding? Such an ungallant exit was the most minor debility of funding his mission on a virtual shoestring; the greater problem was his severe lack of auxiliary resources, such as having no relay satellites.
But then, if there was anything to see up there on the solar equator, perhaps someone else—stationed on the moons of the outer planets, possibly, or any
where along the plane of the ecliptic—might be in position to verify his observation. After all, if Freede were to alert them now and describe what they should look for, then surely they would still give him credit for a first sighting.
But no one Freede could think of, who might be willing to look, was in any better position to see than he was himself. The doctor would gladly impose on his few disciples, the small body of graduate students who had heard his arguments and adopted the sun as their primary study, no matter how eccentric that might have made them in other academic eyes. But alas, at this time they were all to be found down on Earth. And right now the forward tracks of both Hyperion's orbit and the Earth's were coming into alignment on the same side of the sun: the side opposite where that smudge, or whatever it had been, was currently sitting.
Freede briefly considered firing up his ship's maneuvering thruster, a simple fusion ram carved into Hyperion's long axis and fueled with the high-speed particles of the solar wind. With that he could easily reach the delta-vee to enable a shift in orbit. Of course, while firing it he would have to shut down the ship's main heat exchangers and survive with cabin insulation for the duration of the burn. It was the alternative of last resort, of course—
And an unnecessary one. Whatever anomaly Freede had seen, if it was significant, it would just have to survive the thirteen-odd days until the sun's rotation brought it around again to his near side. And by then Hyperion herself would have moved some fifty-four million kilometers farther along in her eighty-eight day orbit. She would have covered one-sixth of the face of the sun and be coming into visual range—in fact, just rising above the anomaly's own horizon—and so be in an increasingly better position to study it. Freede would then get a fix on whatever it was he had observed.
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