Ken Tegnell’s first home was on Alcatraz. At the time—this was in the nineteen-fifties—there was, in addition to the federal penitentiary, a preschool, a post office, and housing for prison employees and their family members. That included Tegnell, who lived with his mother and grandfather, a guard, while his father was stationed in Korea. The whole of Alcatraz Island is less than a tenth of a square mile, so, despite all the security measures and “DO NOT ENTER” signs, the inmates and civilians were never very far apart. Yet even given the proximity to the likes of Whitey Bulger, it was a peaceful place to live. The view was spectacular, almost none of the non-incarcerated residents locked their doors, and almost all of them knew one another and shared the camaraderie of an unusual identity. “We were an odd group of people,” Tegnell jokes, “and that’s why I’m strange the way I am.”
When Tegnell’s father returned from Korea, the family moved away, and then moved often. But eventually Tegnell returned to the Bay Area—this time to attend Berkeley, which, by the late nineteen-sixties, was another island of odd people. While taking an astronomy course there, he attended a lecture by a not yet famous scientist named Carl Sagan. Interested in things that happen in the sky and unmoved by the hippie culture around him, Tegnell joined the Air Force, in 1974. The military taught him to use telescopes and radio arrays, then sent him to the Learmonth Solar Observatory, at the northwestern tip of Australia, to gather data about the sun. He served two tours there, twelve hours from anything that could be called a city—a godforsaken place, as Tegnell recalls it, but gorgeous, with beautiful beaches, terrific fishing, and almost no rainfall year-round. Whether working or playing, he spent his days there looking at the sun.
That is still how Tegnell makes a living, although he hung up his wings in 1996. Today, his job is simultaneously so obscure that most people have never heard of it and so important that virtually every sector of the economy depends on it. His official title, one shared by no more than a few dozen Americans, is space-weather forecaster. Ever since leaving the Air Force, Tegnell has worked for the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center, in Boulder, Colorado: ten hours a day, forty hours a week, three decades spent staring at real-time images of the sun. Eleven other forecasters work there as well. The remaining ones are employed by the only similar institution in the country: the Space Weather Operations Center, run by the Department of Defense on Offutt Air Force Base, in Sarpy County, Nebraska.
Regular, Earth-based weather is such a fundamental part of our lives that we are almost always aware of it and very often obsessed with it; it is the subject of everything from idle chitchat to impassioned political debate. By contrast, most people have no idea that there is weather in outer space, let alone what its fluctuations might mean for our planet. That’s because, unlike everyday weather, you can’t experience space weather directly. It doesn’t make you hot or cold, doesn’t flood your basement or take the roof off your home. In fact, until the nineteenth century, it had almost no appreciable effect whatsoever on human activity. Then came a series of scientific revolutions that made certain technologies, from electricity to telecommunications, central to our lives. Only later did we realize that those technologies are vulnerable to the effects of weather in outer space. The potential consequences are as sweeping as our technological dependence. In 2019, the Federal Emergency Management Agency, surveying the landscape of possible disasters, concluded that only two natural hazards have the capacity to simultaneously affect the entire nation. One is a pandemic. The other is a severe solar storm.
That is why Tegnell’s job is so important. But “space-weather forecaster” is an optimistic misnomer; for the most part, he and his colleagues can’t predict what will happen in outer space. All they can do is try to figure out what’s happening there right now, preferably fast enough to limit the impact on our planet. Even that is difficult, because space weather is both an extremely challenging field—it is essentially applied astrophysics—and a relatively new one. As such, it is full of many lingering scientific questions and one looming practical question: What will happen here on Earth when the next huge space storm hits?
The first such storm to cause us trouble took place in 1859. In late August, the aurora borealis, which is normally visible only in polar latitudes, made a series of unusual appearances: in Havana, Panama, Rome, New York City. Then, in early September, the aurora returned with such brilliance that gold miners in the Rocky Mountains woke up at night and began making breakfast, and disoriented birds greeted the nonexistent morning.
This lovely if perplexing phenomenon had an unwelcome corollary: around the globe, telegraph systems went haywire. Many stopped working entirely, while others sent and received “fantastical and unreadable messages,” as the Philadelphia Evening Bulletin put it. At some telegraph stations, operators found that they could disconnect their batteries and send messages via the ambient current, as if the Earth itself had become an instant-messaging system.
Owing to a lucky coincidence, all these anomalies were soon linked to their likely cause. At around noon on September 1st, the British astronomer Richard Carrington was outside sketching a group of sunspots when he saw a burst of light on the surface of the sun: the first known observation of a solar flare. When accounts of the low-latitude auroras started rolling in, along with reports that magnetometers—devices that measure fluctuations in the Earth’s magnetic field—had surged so high they maxed out their recording capabilities, scientists began to suspect that the strange things happening on Earth were related to the strange thing Carrington had seen on the sun.
Wonderment over the Carrington Event, as it is now known, faded almost as quickly as the auroras—but sixty years later it happened again. In May, 1921, dazzling lights filled the night sky in places as far from the poles as Texas and Samoa; this time, too, spectacle was followed by debacle. “Electric fluid” leaping from a telegraph switchboard set on fire a railroad station in Brewster, New York, while stray voltage on railway signal and switching systems halted trains in Manhattan and, farther north, started a fire at Albany’s Union Station.
Over the years, at odd intervals, this pattern kept repeating: brilliant night skies followed by troubling consequences, which changed in concert with evolving technologies. Teletype machines ceased to operate; or transatlantic cables stopped working; or worldwide radio circuits fell silent; or hundreds of thousands of miles of transmission lines used to send and receive wire stories all went down at the same time. In May, 1967, all three radar sites of the Ballistic Missile Early Warning Systems then maintained by the U.S. Air Force appeared to have been jammed; worried that the Soviet Union was on the verge of attacking, military officials nearly scrambled nuclear-equipped aircraft. Five years later, during the Vietnam War, the United States started sowing the waters outside North Vietnamese seaports with mines that had magnetic sensors, to trigger explosions when steel-hulled vessels passed overhead. Three months after that program began, many of those mines—four thousand of them, according to one contemporaneous source—detonated almost simultaneously. An investigation determined that the plan had been compromised not by Hanoi but by a newly discovered solar phenomenon called a coronal mass ejection.
In time, aided by each new technological difficulty, astrophysicists began to piece together a better understanding of the weather in outer space. But science can take a long time to make inroads into public awareness, let alone public policy, so space weather remained a mostly marginal subject until 2008, when the National Academy of Sciences convened a group of experts to assess the nation’s capacity to endure its terrestrial effects. Later that year, the N.A.S. published a report on the findings, “Severe Space Weather Events: Understanding Societal and Economic Impacts.”
The title was dry; the contents were not. The report noted that the Earth hadn’t experienced a Carrington-size storm during the space age, or, for that matter, during the age of widespread electrification, and that much of the country’s critical infrastructure seemed unlikely to withstand one. Extensive damage to satellites would compromise everything from communications to national security, while extensive damage to the power grid would compromise everything: health care, transportation, agriculture, emergency response, water and sanitation, the financial industry, the continuity of government. The report estimated that recovery from a Carrington-class storm could take up to a decade and cost many trillions of dollars.
That report made headlines, and also made its way to President Barack Obama—who by then had appointed a new FEMA administrator, a man named Craig Fugate. At the time, very few people even within the emergency-response community knew much about space weather. But, by chance, Fugate had crossed paths with the Space Weather Prediction Center earlier in his career; interested in the center’s work, he had made himself into something of a space-weather expert.
As a result, when the White House came knocking to ask if it should be concerned about the N.A.S. report, Fugate was in a position to offer an emphatic yes. The question, for him, wasn’t whether a major solar storm posed a risk to the nation; it was how best to prepare for it beforehand and recover from it afterward. And so, as he began settling into his job, and getting to know the rest of the senior leaders at FEMA, he made a habit of presenting them with a hypothetical situation. “I asked them what they would do if there was a G5 storm,” Fugate told me, referring to the highest classification on the NOAA Space Weather Scale, akin to an F5 tornado or a Category 5 hurricane. “And they go, ‘What’s a G5 storm?’ ” Hoo boy, Fugate remembers thinking. We got a problem.
In space weather, every day is a sunny day. There is no interstellar rain, no interplanetary snow, no sleet spinning off the rings of Saturn; all the phenomena we call space weather originate on the sun. And so, to start, you must shed the idea—implicit in our meteorology and omnipresent in our metaphors—that the sun is a mild and beneficent force, a bestower of good moods and great tans.
In reality, the sun is an enormous thermonuclear bomb that has been exploding continuously for four and a half billion years. Its inner workings are imperfectly understood even by heliophysicists, who sometimes sound less like scientists than like nineteen-fifties comic-book heroes, enthusiastically invoking things like flux tubes and convection zones and galactic-cosmic-ray dropouts. Fortunately, for our purposes, the only two solar phenomena you need to understand are solar flares and coronal mass ejections, both of which stem from the same thing: a buildup of energy in the magnetic field of the sun.
You are probably familiar with the Earth’s magnetic field, which makes all life here possible by deflecting dangerous radiation from outer space. If you could see that field, it would look like a relatively tidy series of rings surrounding our planet, flowing out at the South Pole and reëntering at the North. The solar magnetic field does not look like that. That’s largely because, although the sun is three hundred thousand times more massive than the Earth, no part of it is solid. Instead, it is made of plasma, that strange and mesmerizing fourth state of matter. (Heat up a liquid and it turns into a gas. Heat up a gas and it turns into a plasma, a glowing slurry of electrically charged particles.) As a result, the sun doesn’t have to rotate rigidly, as our planet must. One rotation of the Earth takes twenty-four hours in both Ecuador and Antarctica, but one rotation of the sun takes approximately twenty-five days at its equator and thirty-three days at its poles.
This uneven rotation wreaks havoc on the sun’s magnetic field. Imagine a race in which eight people are lined up on a track, holding on to the same long elastic ribbon. The starting gun fires and the people start running. The two in the middle are the fastest and the two on the ends are the slowest, so after a while the middle two are far ahead and the ribbon looks like this: > . If the race kept going and the runners’ speeds remained constant, the two middle runners would eventually lap the others, and the ribbon would cross over itself. The longer the race lasted, the more tangled the ribbon would become.
That’s what happens to solar-magnetic-field lines. They twist and crisscross until clusters of them pop up from the sun’s surface, in huge loops that generate enormous amounts of energy. (Think of the energy stored in a rubber band when it is twisted and stretched. Now imagine that the rubber band is a hundred thousand miles long.) The ends of these loops are sunspots, the phenomenon that Carrington observed in 1859. He could see them readily enough for two reasons. The first is that they are darker than their surroundings, because they are a couple of thousand degrees cooler; the intensity of their magnetic fields hinders the flow of hot gas across the sun. The second is that they are large. An average sunspot is the size of the Earth, while the biggest ones can be ten times larger.
Forecasters like Ken Tegnell watch sunspots for the same reason that regular meteorologists watch low-pressure areas in the tropics: to see if a storm is forming. This happens when one of those twisted magnetic fields suddenly rips apart, then snaps back together again. That rearrangement returns the magnetic field to a more stable, lower-energy state, while releasing the excess energy into space in two different forms. The first is a solar flare: a burst of radiation that can range across the electromagnetic spectrum, from gamma rays and X rays to radio waves and visible light. Solar flares contain a colossal amount of energy—enough, in a large one, to meet our planet’s power needs for the next fifteen or twenty thousand years. The second is a coronal mass ejection: a billion-ton bubble of magnetized plasma that explodes off the surface of the sun. These two phenomena can occur separately, but when large ones occur together they mark the beginning of a major solar storm.
The forecasting room of the Space Weather Prediction Center is a dimly lit ground-floor office with no exterior windows. Nonetheless, in a sense, sunlight is everywhere. Banks of monitors run the length of one wall, filled with real-time images of the sun. Some show only the disk, others only the corona, others the entire star filtered through different wavelengths of light, turning it pale pink and brilliant yellow, electric blue and neon green. Two large images in the center show the sun as a writhing riot of orange and gold, the loops and filaments of its magnetic field lines rendered visible not by scientific instruments but by its own plasma, which is drawn to those field lines the way iron filings are drawn to bar magnets. Viewed this way, the sun does not make you want to grab a paperback and lie in a hammock. It looks like a volcanic eruption as seen from deep inside the caldera; it looks like a wildfire raging beneath forty billion hurricanes; it looks like, when it is over, there will be no survivors.
Surrounded by all of this, unfazed, Tegnell is logging in for his shift. In the hallway just outside, a mannequin stands upright in a NASA uniform. The uniform is the old-school, pale-blue kind, and the mannequin is pale and old school, too—crewcut, chisel-jawed, permanently twentysomething. Tegnell does not look like that. Bigger, bearded, older, he looks like the guy in the disaster movie who has the right combination of grit, experience, and indifference to authority to save the day. At present, he is eye level with a brace of computers, the screen of each one covered in flowing lines, as if the solar system were hooked up to half a dozen heart-rate monitors.
Some of the information filling those screens comes from terrestrial observatories, like the one where Tegnell used to work. The rest comes from space-based equipment on satellites, managed, variously, by NASA, NOAA, and the European Space Agency. Most of those satellites are in orbit twenty-two thousand miles above the Earth, a hundred times farther away than the International Space Station; a few are in orbit a million miles away, or about one per cent of the distance to the sun. From these outposts, they transmit data to the forecasting room, where it is Tegnell’s responsibility to interpret the contents, detect anything unusual, issue twice-daily forecasts, and, when necessary, activate a suite of watches and warnings.
Tegnell loves his job best when nothing is happening in the room—no groups of engineers trekking through, no stray journalists hanging around—but when many things are happening up in the sky. That makes some stretches of his professional life duller than others, because sunspots follow an eleven-year cycle, during which their activity goes from infrequent (solar minimum) to frequent (solar maximum). We are currently headed toward solar maximum, with activity on the sun expected to peak sometime between now and 2025. That cycle is not wholly determinative; a solar maximum can pass by uneventfully, while a powerful storm can happen during solar minimum.
Still, solar maximum does tend to make Tegnell’s job more interesting. As we talk, an automated voice keeps informing him that a flare has been detected, with the same impassive insistence of Siri saying, “Proceed to the route.” Tegnell ignores it, having already determined that the flare is too small to produce any effects on Earth, except possibly some auroras for people living near polar latitudes. (Auroras are the only pleasant by-product of charged particles entering our atmosphere, where they’re channelled north and south along magnetic-field lines and interact with nitrogen and oxygen molecules, causing them to produce interesting colors.) But then something else leaps off the edge of the sun: a fountain of plasma that looks, to my untrained eye, enormous. “It is enormous,” Tegnell affirms. “It’s just incredible.” It is not, however, headed toward the Earth.
“I know,” Tegnell’s colleague Bill Murtagh says as he watches me watching. “It’s stunning. I’ve been doing this for twenty-five years and I’ve never yet found it boring.” Like Tegnell, Murtagh arrived at the Space Weather Prediction Center via the U.S. Air Force, albeit more circuitously, as his Irish accent suggests. (He owes his American citizenship to the fact that he was born during a parental stint in the U.S., where his mother worked for Ogden Nash, taking care of his grandchildren.) Unlike Tegnell, he enjoys collaborating with other people. At swpc—which is pronounced “swipsy,” like “tipsy”—he coördinates space-weather-preparedness efforts with government officials, emergency managers, and the private sector, and he doesn’t mind being loaned out to the White House Office of Science and Technology Policy and working with the National Security Council. When a big storm starts materializing on one of the monitors in the forecasting room, it is Ken Tegnell’s job to notice. It is Bill Murtagh’s job to help minimize the storm’s impact on everything it might derail, damage, or destroy.
That is a long list, because solar storms affect a broad, strange swath of the human endeavor. For instance, outside the swpc forecasting room, in a glass case displaying old astronomical devices and a statue of a sun god, there is a life-size model of a homing pigeon. Pigeons navigate partly by tracking the Earth’s magnetic field; when it behaves in uncharacteristic ways, a pigeon race can end in a “smash,” the term of art for events in which many birds fail to return home. Since the most highly prized pigeons can be worth more than a million dollars, some pigeon racers have become dedicated subscribers to swpc’s space-weather alerts. Other constituents are interested for even more arcane reasons. One of Murtagh’s favorite phone calls came from a man who wanted to know if it was true that solar storms could interfere with G.P.S. signals. When Murtagh said yes, the man had a follow-up question: How did those storms affect electronic ankle bracelets? (“You know,” Murtagh told the caller, “I’m not too familiar with that technology.”) But the sectors that bear the brunt of bad space weather are anything but niche interest groups. They are the backbone of modern society: telecommunications, aviation, space-based technology, and the power grid.
Most solar storms do not hit the Earth, for the same reason that most baseballs don’t hit one particular person in the stands. But, when a storm does get here, it gets here fast. Some of the radiation from the solar flare arrives in a little more than eight minutes: the amount of time it takes anything travelling at the speed of light to cross the ninety-three million miles between us and the sun. All that energy smacking into our atmosphere further ionizes the ionosphere, its upper reaches. The result, in a severe storm, is a partial blackout of low-frequency radio wavelengths and a complete blackout of high-frequency wavelengths across the entire side of the Earth that’s facing the sun. Those blackouts, which can last up to several hours, disrupt ham radios, AM radio, ground-to-submarine communications (used by the Navy), backup ground-to-air communications (used by both military and civilian flights), and other backup communication, navigation, and timing systems used for military, government, and maritime purposes.
That is the first phase of a solar storm. Meanwhile, from the moment they formed, the flare and the coronal mass ejection began transferring energy to any protons and electrons in their path, accelerating them to relativistic or near-relativistic speeds. When those enhanced protons and electrons, known as solar energetic particles, reach our atmosphere, sometimes in just tens of minutes, they form the second phase, known as a solar-radiation storm.
As that name suggests, a solar-radiation storm can harm humans, although only if they happen to be up in the sky while such a storm is taking place. For people on airplanes flying routes over the poles (where energetic particles, following magnetic-field lines, tend to concentrate), that risk is minor; nonetheless, such flights get space-weather reports from swpc before takeoff, and will typically reroute if a big storm is expected. For astronauts, however, severe radiation storms are more of a concern. Those on the International Space Station benefit from the attenuated but still extant protection of the Earth’s magnetic field, and during extreme radiation events they can take cover in the better-shielded parts of the station. But for those beyond our atmosphere such a storm could be lethal, either immediately or because radiation sickness would render them unable to perform life-critical functions. One obstacle to some of the space exploration currently being contemplated is that the moon and Mars lack a magnetic field to deflect the sun’s radiation; as a result, absent adequate shelter, both are extremely dangerous in a solar storm. Only retroactively did it become apparent how lucky NASA was that no such storms happened during the Apollo missions.
At the moment, though, the number of people in outer space—fewer than a dozen—pales in comparison with the number of satellites in outer space: more than eight thousand. Like us, those satellites are imperilled by solar-radiation storms. For one thing, solar energetic particles can pass straight into the satellites, physically damaging hardware and hijacking software by randomly changing ones to zeros or zeros to ones. For another, as those particles bombard a satellite, different parts of it can build up different levels of charge, and the electricity can arc from one area to another, attempting to neutralize itself and, in the process, damaging or disabling the onboard electronics.
Finally, enhanced solar radiation increases the density of certain regions of the Earth’s atmosphere, which increases the drag. This is particularly problematic in lower Earth orbit (up to about twelve hundred miles above the surface of our planet), where more than eighty per cent of all satellites are found. As drag increases, those satellites can shift out of place, leaving both their owners and the North American Aerospace Defense Command scrambling to find them in order to maintain functionality, prevent collisions, and avoid confusion about their identity: unidentified intruder or old friend in a new place? At best, satellites experiencing this drag must use more fuel to maintain orbit, thereby shortening their life spans; that’s why, back in 1979, Skylab crashed to Earth sooner than expected. At worst, they lose orbit entirely, burning up on reëntry. In February of 2022, SpaceX, the space-exploration company co-founded by Elon Musk, launched forty-nine new satellites as part of its Starlink system, which aims to provide sky-based Internet access to paying customers anywhere on Earth. The company knew that a storm had started just before the launch date, but it was a mild one—a G2, the second-lowest category on NOAA’s geomagnetic storm scale—and internal modelling suggested that the satellites would be fine. One day after launch, thirty-eight of them lost orbit and suffered catastrophic failure.
SpaceX still plans to launch tens of thousands of satellites in the coming years, and other entities are likewise expanding their fleets, deploying space-based technology for everything from wildlife tracking to intelligence gathering. But, of all the satellites in the sky right now, none are more crucial than those which constitute our Global Positioning System—or, to use the more universal term, G.N.S.S., the Global Navigation Satellite System.
G.P.S. satellites are not endangered by drag, because they are not in lower Earth orbit; up where they hang out, there is not enough atmosphere left to affect them. But, to reach receivers on the ground, signals from those satellites must cross some twelve thousand miles of space. During a solar storm, when our ionosphere is disturbed, those signals get distorted, much the way light bends when it passes through water, leading to location inaccuracies of tens or, in rare cases, hundreds of metres. Those inaccuracies generally self-correct when the storm subsides, and they don’t really matter if you’re using G.P.S. just to remind yourself which exit to take for the airport. But an increasing number of processes require constant access to ultra-precise location data, including military operations, aviation, crop management, bridge building, and oil and natural-gas exploration, especially off deep-sea platforms, where exact positions must be maintained during underwater drilling operations regardless of wave action and drift.
The more important service provided by the Global Positioning System, however, is not about space but about time: every G.P.S. satellite carries multiple atomic clocks, normally accurate to within a billionth of a second, which transmit hyperaccurate temporal information known as G.P.S. timing signals. Those signals are one of our most essential pieces of invisible infrastructure. Cell-phone companies use them to manage the flow of data over their networks. Media companies use them to broadcast programs, chopping up large data streams into smaller packets to transmit them, then recombining them upon arrival based on the time stamp. Power companies use them to help regulate the flow of electricity from source to destination, protecting against surges and blackouts. Computer applications use them to coördinate any situation in which two or more users are working on the same project in different locations. The financial industry uses them to track mobile banking transactions and to time-stamp every trade—a crucial traffic-control system in a world where hundreds of thousands of financial messages are processed every second.
Like G.P.S. location accuracy, G.P.S. timing accuracy can suffer during a solar storm. The longer and more severe the storm, the more those errors compound, until the systems that depend on the signals no longer work correctly, or work at all. Backup programs are available; the Federal Aviation Administration, for instance, has alternative capabilities to keep planes flying safely when G.P.S. fails. Over all, though, incorporation of such alternatives remains limited, for a straightforward reason: G.P.S. is a service that our federal government provides free of charge. As the Department of Homeland Security dryly noted in a 2020 report, “Without regulatory requirements or positive benefit-cost equations, adoption of non-G.N.S.S. services is unlikely.”
In the meantime, our primary source of navigation and timing information remains vulnerable to the vicissitudes of weather on the sun. So do the thousands of other satellites that increasingly fill our skies, courtesy of a young, booming, and largely unregulated industry. This worries the generally unflappable Bill Murtagh. “It’s a Wild West out in space right now,” he says. His assessment of satellite companies is blunt: “I do not think they are ready for a major space-weather event.” If he is right, when that event happens, large portions of our life could be compromised: information, communication, entertainment, economic activity, national security. But all those are our vulnerabilities just in the sky. By most accounts, when the next extreme space storm hits, the real problems will be the ones on the ground.
If a solar flare is something like the muzzle flash of a cannon, a coronal mass ejection is the cannonball: slower, but more destructive. It takes anywhere from fifteen hours to several days to reach our planet, by which time it has expanded enormously in volume. Once it arrives, it smashes into our magnetosphere, flattening whichever side is facing the sun (that is, the daytime side) and sending the nighttime side streaming away from the Earth, like a wind sock in a gale. If you remember Faraday’s law, you know that moving a magnetic field around produces an electric current. And so it is ultimately the Earth’s own storm-tossed magnetosphere that induces excess electricity in our planet, thereby initiating the third and final phase of a space-weather event: the geomagnetic storm.
Although that storm can affect anything long and metal (pipelines, railroad tracks), it poses the gravest danger to power grids. In the United States, our grid is divided into three regions. The Eastern Interconnection runs from the East Coast to the Rocky Mountains; the Western Interconnection runs from the Rockies to the Pacific Ocean; Texas, in true Lone Star style, goes it alone. For the most part, power can’t flow from one region to another—which is why, when seventy-five per cent of Texas suffered blackouts during a winter storm in 2021, no outside energy providers could help. But, within each region, electricity flows freely—and so can electrical problems, as when, in 2003, a shorted power line in Ohio caused a blackout across much of the Midwest, the mid-Atlantic, and the Northeast, leaving fifty-five million people in the dark.
All this infrastructure, which continues across the border into Canada to form the North American Power Grid, is also known as the bulk-power system, because it handles energy transmission, not energy distribution. Distribution involves sending electricity from a local substation to everything nearby that needs it—schools, stoplights, factories, the toaster in your kitchen. Transmission gets power to that substation, from one of the more than six thousand generation facilities on the North American grid (nuclear plants, hydroelectric dams, solar farms, etc.), via more than half a million miles of line.
The crucial nodes in this vast network are transformers. Power enters your home at a hundred and ten volts, but voltage that low can’t be sent from a coal plant in West Virginia to your laptop charger in Alexandria; too much energy (in the form of heat) would be lost in transit. Instead, a transformer at the power plant ramps up the electricity to hundreds of thousands of volts, so that it can be transferred efficiently over long distances; once it reaches a substation, another transformer ramps the voltage back down until it can safely enter your home. Whatever its voltage, all that power flows through the grid as alternating current, moving at a constant frequency of sixty hertz.
Hold that thought; here comes the coronal mass ejection. It smacks into our magnetic field, warping it—or, in severe storms, temporarily ripping part of it open—and setting in motion the chain of events that sends additional electric charge into the planet. Some of that charge, which is known as geomagnetically induced current, dissipates harmlessly, because it flows into a part of the Earth that excels at conducting electricity—salt water, say, or sedimentary rock. But, in places where the underlying rock is a poor conductor, the current must go elsewhere. Like all current, it follows the path of least resistance, and the least resistant path of all is the one designed to conduct electricity: the power grid.
By unfortunate chance, some of the least conductive bedrock in the United States is the very old metamorphic and igneous rock of the Appalachian Mountains and the New England Highlands—the geological substrates of Boston, New York, Philadelphia, Washington, D.C., and much of the rest of the Eastern Seaboard, home to half the country’s population. As detailed hazard maps recently created by the geophysicist Jeffrey Love and a team of his colleagues at the United States Geological Survey show, some other parts of the country, notably the Midwest, are likewise vulnerable to geomagnetically induced currents.
What makes these currents so disruptive is not their strength—they are actually quite weak—but their form. The power grid is built for alternating current, but geomagnetically induced currents are basically direct. The collision of these two currents can lead to the inability to transfer power efficiently, large temperature spikes inside transformers (which emit unholy groans and bangs under the strain), relays and other equipment tripping off-line, and, on a very bad day, voltage collapse. Mark Olson, a member of NOAA’s Space Weather Advisory Group and a manager of reliability assessments at the North American Electric Reliability Corporation—the nonprofit agency tasked by the Federal Energy Regulatory Commission and Canada’s provincial governments with keeping the continent’s power grid sound and secure—summed this up for me succinctly: “blackout.”
This can all happen almost instantly. On March 13, 1989, a coronal mass ejection struck the Earth; within ninety seconds, transformers on the Quebec power grid malfunctioned, dozens of safety mechanisms failed, and the entire grid shut down, leaving almost a quarter of the population of Canada in the dark. That geomagnetic storm—which also triggered outages in the U.K. and Sweden, destroyed a transformer at a nuclear power plant in New Jersey, and caused at least two hundred other issues on the North American grid alone—was strong, but not exceptionally so. Based on magnetometer readings, auroral latitudes, and other fingerprints left behind by solar storms, scientists now believe that at least three storms in the past hundred and fifty-odd years—the Carrington Event and others in 1872 and 1921—were roughly an order of magnitude more powerful.
All three of those storms took place before the power grid existed. The question that troubles space-weather experts—and divides them—is what will happen the next time a comparable one strikes. Some people think that the Quebec event was a wake-up call—the perfect-sized storm, really, large enough to teach a lesson without being large enough to cause a catastrophe. But, per the N.A.S. report, any gains following the Quebec storm were offset by trends in America’s bulk-power system, which came to rely on ever-larger amounts of power travelling through ever-longer transmission lines. A study commissioned by the federal government and summarized in the report found that a storm the size of the 1921 event would cause large regions of the grid to fail, with impacts that “would be of unprecedented scale and involve populations in excess of 130 million”—close to half of all Americans. The report estimated the cost of a storm like that as “$1 trillion to $2 trillion during the first year alone . . . with recovery times of four to ten years.”
Fifteen years later, some experts believe that was the wake-up call: that the 2008 report, in its sober-minded scariness, inspired reforms that will make the next severe solar storm more nuisance than nightmare. Bill Murtagh worries about satellite companies, but he thinks that most power companies take space weather seriously and are doing their best to prepare for it. Mark Olson, of the North American Electric Reliability Corporation, concedes that solar storms present “a very challenging risk” to the energy sector, not least because we still know relatively little about them. But, he says, when a major one happens, “the North American grid won’t be taken by surprise.” And he points to a federal directive that, as of this January, requires every provider of bulk power to have a plan in place to deal with a “benchmark geomagnetic disturbance event.”
That directive is important, but the benchmark itself is troubling. It was established by using thirty years of magnetic-field data to extrapolate the likely magnitude of a once-in-a-century storm. The resulting standard is clear, uniform, achievable, extremely useful during most solar storms, and wholly inadequate for severe ones. As Olson acknowledged, the federal benchmark is now widely believed to be weaker than the Carrington Event.
That wouldn’t matter if the Carrington storm were an outlier, likely to happen only once every several hundred years. But, in reality, it might not even have been the worst storm of the nineteenth century; the one in 1872 was at least as strong. We also know, from data collected by satellite, that a more powerful storm narrowly missed the Earth in 2012. As that suggests, an extreme geomagnetic storm—the swpc people call it a G5-Plus, at the upper threshold of the highest NOAA category of severity—could be a more common event than previously thought. Some scientists now believe there is an approximately twelve-per-cent chance of one striking the Earth in the next decade.
That scares some experts. One of the eminences in the field of space-weather studies is Daniel Baker, who was the head of space-plasma physics at Los Alamos National Laboratory and a division chief at NASA’s Goddard Space Flight Center before going to the University of Colorado to lead its Laboratory for Atmospheric and Space Physics. “I do not want to be unduly alarmist,” Baker told me. “But I do want to be duly alarmist.” Like so much American infrastructure, he notes, our bulk-power system is underfunded and aging, while demand on it keeps rising—not only from population growth but from an incommensurate increase in our energy use. As a result, he says, the grid is operating “closer and closer to its maximum stress level.” In that condition, it cannot easily absorb the additional stress of a solar storm.
Our aging grid could be updated, but the factors that make doing so expensive and time-consuming will also dramatically compound the effects of a severe solar storm. “Transformers are not just something you can go to Home Depot and buy,” Baker points out; each one is idiosyncratic, a half-million-pound object designed specifically for one of the fifteen hundred-plus entities, from publicly traded companies to energy coöperatives, that together constitute the power grid. As a result, transformers can’t be stockpiled. They are almost always built to spec, and they are almost all made abroad, which increases shipping times and leaves them vulnerable to political conflict and supply-chain issues. Even under optimal circumstances, the typical lead time to replace a transformer is at least a year. If enough of them fail in a solar storm, the recovery will not be measured in days (the length of time it took to get the power back after the Texas winter storms) or weeks (the length of time it took after Hurricane Katrina). It will be measured, almost unthinkably, in months and years.
That’s one reason Craig Fugate, the former FEMA administrator, thinks the one-to-two-trillion-dollar figure in the N.A.S. report is “probably on the low side.” But he also raises a problem that extends beyond the power grid: because solar storms affect an unusually wide geographic area and an unusually broad range of technologies, they are more likely than other disasters to cause cascading failures. A malfunction in one part of the grid forces electricity to flow elsewhere, overburdening a second part, which is then more likely to malfunction as well; the more such problems you string together, the greater the burden on the remaining parts, and the more likely a catastrophic failure. And what is true of the disaster is also true of the disaster response. Unlike terrestrial hazards, solar storms are not, in FEMA-speak, “geofenced.” They can affect large areas of the world, which minimizes access to outside help in the aftermath. If an earthquake devastates Los Angeles, aid can pour in from neighboring regions. But, if a solar storm devastates New York, anywhere close enough to help will likely be devastated, too
Above all, Fugate fears that, because space weather affects so many technologies, a severe storm could expose dependencies among them that we did not fully appreciate, or did not recognize at all. Our vast and interrelated technological infrastructure could turn out to harbor a single point of failure—a component, no matter how central or trivial, whose malfunction shuts the whole thing down. Many experts regard G.P.S. signals with alarm for this reason; as a 2021 report by the National Security Telecommunications Advisory Committee noted, the signals are used so ubiquitously in so many critical sectors that “their vulnerabilities pose a near-existential threat.” Alternatively, an individual system that seems robust in isolation might not respond as expected when other systems to which it is connected simultaneously experience powerful stressors—especially when those stressors involve, as Fugate put it, “more unknowns than knowns.” That is true not only of technology but also of the people who operate it; we do not always perform at our best when things around us start malfunctioning. In this kind of “system of systems,” even seemingly minor problems can concatenate in calamitous ways.
Baker worries about this as well. “We’ve built ourselves into a cyber-electric cocoon,” he says, “and a lot of risk analyses show that when you start to lose nodes in that kind of a connected system it can propagate in very unpredictable ways. And there’s nothing outside it.” In a closed loop like that, a disaster is disastrous not only because of the problems it causes but because of the solutions it eliminates. Post-disaster relief and recovery operations rely on functional transportation systems, but airports, railroads, gas pumps, stoplights, and an increasing number of vehicles all need electricity. Emergency dispatchers rely on sophisticated communication and mapping technologies, but those technologies rely on working computers and satellite transmissions. Power companies need water supplies, but water companies need electricity. Knock over the wrong domino and down goes, as the N.A.S. report put it, “just about every critical infrastructure including government services.” Baker, who led the team behind the report, suspects that we will see a devastating storm within a few decades, and that most of us alive today will suffer through those serial failures. “Maybe here in Colorado, we can go out and hunt elk or something,” he says. “But I’d be very concerned about the major metropolitan areas.”
All these problems have a meta problem. Radio blackouts, communication disruptions, power-grid problems: to an uncanny degree, solar storms mimic malicious actors trying to sabotage technology that is central to our economy and safety. Because of this, one of the most important functions of swpc and the Defense Department’s Space Weather Operations Center is attribution—determining whether a given anomaly was caused by bad weather in space rather than by a technical malfunction or deliberate interference. Such determinations must be accomplished quickly: if you have a radar system that’s jammed or a missile-defense system that’s malfunctioning, you can’t wait around for long to figure out why. “When we see something, we’ve got five to ten minutes or less to get this stuff out,” Tegnell says. Delay can be disastrous; in matters of national security, Murtagh notes, “a lot can happen in ten to fifteen minutes.”
In part to facilitate these assessments, swpc makes all its space-weather information publicly available. “We have no problem sharing information across the world,” Murtagh told me. The U.S. has a vested interest in the global community not mistaking natural hazards for foreign adversaries; for that matter, given international supply chains and international commerce, the United States has a vested interest in the global community minimizing disruptions from solar storms. Whether it can do so is impossible to say; we don’t even know how prepared the U.S. is, and the world is the ultimate system of systems, as we all learned at great cost from the pandemic. But it is difficult to be optimistic. For many nations, especially in the developing world, better space-weather preparedness is low on the list of priorities for infrastructure improvements.
And yet, precisely because solar storms can cause the same problems as enemy agents, better space-weather preparedness amounts to better preparedness over all. “I think of space weather as a stand-in for all those other disruptions,” Kathryn Draeger, an agronomist at the University of Minnesota who researches how to mitigate the impact of solar storms on agriculture, told me. “A terrorist attack on our grid, an electromagnetic pulse, a natural disaster, a pandemic—if we can figure it out for space weather, we will be better protected from all these other major disruptions.”
In theory, we’ve already figured out some of it. We could require backup navigation and timing systems; we could move away from ultra-long, ultra-high-voltage transmission lines. Certain new technologies could help, such as devices that block geomagnetically induced currents from entering the grid, as could a return to some old ones. The Army, concerned about overreliance on vulnerable technologies, has reinstated courses in orienteering, and the Navy has resumed teaching sailors how to use a sextant.
Still, persuading people to implement safety measures is difficult, because severe solar storms are what people in emergency management sometimes call low-frequency, high-consequence events. Such events are emotionally, ethically, and pragmatically vexing, and we respond to them in curious and inconsistent ways. In our private lives, we tend to focus on the high consequences: your nine-year-old will almost certainly not be kidnapped while playing alone at the local playground, but you don’t let him do so, because the potential cost is too devastating. By contrast, corporations and nations tend to focus on the low odds, and therefore wave away the possible consequences. “I’m working with people and they’ll say, ‘Why do I need to spend a cent on this issue? I’ve been here for forty years and I’ve never seen a problem,’ ” Murtagh told me. “And I look at them and say, ‘I don’t know what to say to you.’ ” As far as the sun is concerned, “the Carrington Event happened one second ago. And it will happen again.”
We don’t know when, of course; there is so much we do not know. Before Tegnell became a space-weather forecaster, he was a regular-weather forecaster, and he remains acutely aware of the difference between them. It’s not just that you have to go from thinking on the scale of cities and counties to thinking on the scale of millions of miles. It’s that with solar events “you have no idea what goes on in ninety per cent of them.” Space-weather forecasting, he believes, is where terrestrial meteorology was seventy-five years ago. Back then, we were farther from today’s reality, of minute-by-minute weather information on your phone, and closer to the reality of sixteenth-century mariners or third-century shepherds, for whom hurricanes and blizzards happened more or less out of nowhere, and for whom our vulnerability to severe weather seemed immutable and inevitable, laid down as our lot in life since that first Biblical flood.
Someday, Tegnell says, our current understanding of space weather will seem similarly sparse. We will put more and better instruments in space; we will learn more about the physical dynamics of the sun and their effects here on Earth. Whether infrastructure improvements will keep pace with that knowledge is beyond his job description, and beyond his ken. He is hoping to retire this year, after half a century of service to the United States. He is not worried about being bored. He has spent a lifetime studying solar activity and doesn’t figure that will change all that much. “I’m the kind of guy,” he told me, “who likes looking at sunsets.” ♦
