Mikhail said dryly, And of course the ease of controlling information from the Moon is purely coincidental.
Siobhan frowned. We have to take security seriously, sir. The governments really have no idea of what theyre facing yet. Until they do, information, unfortunately, must be managed. A panic could be vastly damaging in itself.
Rose subsided, but she was glowering, and Siobhan hoped beyond hope that she hadnt already made an enemy.
As brightly as she could she said, Lets start by making sure were all singing from the same hymn sheet. Doctor Martynov, I wonder if youd be good enough to tell a mere cosmologist how the sun is supposed to work.
It will be a pleasure. With a showmans sense of theater Mikhail stood and made his way to the front of the room.
All cosmologists know that the sun is fueled by fusion fire. What most cosmologists dont know is that only the innermost heart of the sun is a fusion reactor. The rest of it is special effects Mikhails Russian accent was movie-actor thick, but quite compelling.
During her training, Siobhan had of course studied the sun. She had learned that the sun, like all stars, is simple in principle, but as the nearest star the sun had been scrutinized in minute detail. The detail, it turned out, was rather overwhelmingly complex and still little understood, even after centuries of study. But it was that detailed behavior that now seemed to be endangering humankind.
The sun is a ball of gas, mostly hydrogen, more than a million kilometers widethat is, as wide as a hundred Earths strung side by side, and as massive as a million Earths. The source of its vast energy output is its core, a star within a star where, in complicated chains of reactions, swarming nuclei of hydrogen fuse to helium and other heavier elements.
The fusion energy must pass out through the body of the sun from the hot core to the cold sink of space, driven by temperature differences as surely as a head of pressure drives water through a pipe. But the core is swaddled by a thick belt of turgid gas called the radiative zone, opaque as a brick wall, through which the inner heat passes in the form of X-rays. In the next layer out, the convective zone, the densities have lessened to the point where the suns material can boil, like a pan heated from below. Here the core heat continues its journey to space by powering huge convective spouts, each many times taller than Earth, ascending at not much more than walking pace. Above the convective zone lies the visible surface of the sun, the photosphere, the source of sunlight and sunspots. And just as the meniscus of a boiling pan of water will organize itself into cells, so the sun bubbles with granules, constantly changing, tiling the photosphere like a Roman mosaic.
So immense and compressed are these layers that the sun is all but opaque to its own radiation; a given photons worth of energy takes millions of years to struggle from core to surface.
Once released from its cage of gases, the core energy, in the form of light, races away at lightspeed as if with relief, spreading with distance as it travels. At the distance of the Earth, eight light-minutes from the photosphere, sunlight still delivers about a kilowatt of power per square meterand even at a distance of light-years the sunlight is bright enough for any eyes there to see it.
As well as the light it emits, the sun breathes a constant stream of hot plasma into the faces of its circling children. This solar wind is a complex, turbulent breeze. At certain frequencies of light can be seen dark patches on the suns surfacecoronal holes, regions of magnetic anomaly, like flaws in the sun itselffrom which pour higher-energy streams of solar wind. The turning sun sprays these streams around the solar system in spiral washes, like an immense lawn sprinkler.
Mikhail said, We watch out for those sprinkler streams. Every time the planet runs into one we get problems, as the Earth and its magnetosphere are battered by high-energy particles.
Still more problems are caused for the Earth by the suns occasional irregularities. Mikhail said, You have coronal mass ejectionslike the monster that hit us on June 9large-scale outpourings of plasma flung at us from the suns surface. And then you have flares. These detonations on the suns surface, powered by magnetic flaws, are the largest explosions in the modern-day solar system, each amounting to the blast of billions of nuclear weapons. Flares bombard us with radiation from gammas to radio waves. Sometimes they are followed up by what we call solar proton eventscascades of charged particles.
The restless sun follows an eleven-year solar cycle, at the peak of which sunspots swarm and flares erupt with much more vigor than at its minimum. Mikhail sketched the accepted mechanism behind the solar cycle. A meridional flow of plasma over the suns surface from equator to poles carries the relics of sunspots north and south. At the poles the cooling material sinks down into the body of the sun as far as the base of the convective zone, and then migrates back toward the equator. But the magnetic scars left by sunspots linger on through this cycle, ghosts that seed the next generation of active regions.
Mikhail described the complicated relationship of sun, Earth, and humanity.
Even in historical times the suns variability has affected the Earths climate. For more than seventy years, from around 1640 to 1710, very few sunspots were observed on the suns faceand the Earth was plunged into what the climatologists call the Little Ice Age. Europe suffered severe winters and cool summers; at the peak of it, in 1690, London children ice-skated on the Thames.
In the electronic age, a growing dependence on high technology made humans much more vulnerable to even mild solar tantrums. In April 1984 a flare knocked out communications on Air Force One; President Reagan, over the mid-Pacific, was left incommunicado for two hours. Before June 9 the most intense storm on record had occurred in September 1859; that one had melted telegraph wires.
We actually came close to that again in 2003, Mikhail said. The sun suffered two eruptions in successive days, aimed right at the Earth. We were saved from more severe effects only by a chance alignment of magnetic fields.
Rose Delea was getting restless. All these phenomena are well known.
Mikhail said, Yes, we think we are getting a handle on measuring the effects of these different solar glitchesand predicting them, though thats still more an art than a science He put up a slide of three space weather scales that the current Space Weather Service had inherited from the old American Space Environment Center, and had elaborated on since. You can see we describe three types of problem for Earth: geomagnetic storms, solar radiation storms, and radio blackouts. Each type is calibrated with these scales, from one to fiveone being minor, and five being severe.
Siobhan nodded. And June 9
June 9 was principally an outcome of a coronal mass ejection, and would be measured by our G-scale, our geomagnetic-storm scale.
And its rating?
Off the scale. June 9 was unprecedented. But the irony is that the event was better predicted than any solar glitch in history, thanks to Doctor Mangles. He glanced at Eugene.
But Eugene, as distracted as ever, didnt react to the cue; he seemed barely aware that the rest of the group existed.
There was an awkward silence. Bud called for a break.
You had to fetch your own coffee, it turned out; there were no spare hands to fetch and carry. And there were no digestive biscuits, not one on the whole damn Moon.
A line quickly formed at the coffee spigot at the back of the room. But Mikhail, near the front of the queue, picked up two plastic beakers of coffee and tentatively approached Siobhan, who accepted a beaker gratefully. Mikhails face was lugubrious and crumpled, and his voice was warm and rich; Siobhan liked him instinctively.