Even if you're not on a galactic mission, what's out there could hurt you. Alan Burdick assesses the risks of solar weather

August 26, 2009

Rain, sleet, hurricanes—how tiresome, how 20th-century. We want globalized, digitized, new-millennium dotcom weather. The National Oceanic & Atmospheric Administration's Space Environment Center knows exactly what we want. We want space weather.

If you haven't heard of space weather, don't bother checking the Weather Channel, or AccuWeather, or Al Roker: they're old media. Space weather is all-encompassing, profound. It has its own Web site: www.spaceweather.com. Log on and you'll learn what causes space weather—the ceaseless rain of high-energy particles that the Sun showers on Earth—and what, in turn, space weather causes. Its effects are surprisingly widespread, leading to radio blackouts, power-grid failures, and cell-phone havoc. It can also increase the risk of cancer in astronauts and very frequent fliers by exposing them to hourly doses of radiation up to 100 times as powerful as a chest X ray.

The advent of space weather reflects the growing awareness (among scientists, at least) that our planet's environment is a whole lot bigger than we had thought. This knowledge has led to new research (in March, NASA launched a satellite to study the phenomenon), new special events (you mean you missed Space Weather Week?), and, publicists hope, a new buzzword.

"'Space environment,'" says Barbara Poppe, a spokeswoman for the Space Environment Center. "What does that mean?'Space weather' is clearer: it's weather, but in space."

The year 2000, as it happens, is a big one for space weather. In slow years the Sun is calm and relatively storm-free—"comatose," says Joe Kunches, a forecaster at the center. Every 11 years or so, however, it boils to a peak of activity. The last "solar max" was in 1989; the next one is… right now. So you'll be experiencing more space weather than ever, even if you're not aware of it. "Increasingly," Kunches says, "the technology that allows us to communicate around the world is affected by what the Sun does."

The sun is constantly shedding its skin, emitting a "solar wind" of high-energy particles that blows in all directions. From time to time, storms erupt on the Sun's surface, sending Earth an extra hail of protons a couple of days later—the seeds of space weather.

Fortunately, we mere mortals are spared the harsh effects of solar wind by Earth's magnetic field—the magnetosphere—which acts as a sort of planetary deflector shield. A strong solar storm, however, can still make its presence felt. Solar flares, for instance, which appear as bright spots on the Sun's surface, give off light at a higher intensity than normal (typically in the form of X rays). If the energy strikes Earth, it could disrupt communication and radio-navigation satellites for half the planet. Two years ago, a geomagnetic storm knocked out service on cell phones across North America. (You may have found it amusing then, but now that you own one…)

The money shot of solar storms, though, is the "coronal mass ejection": an invisible mass of charged particles—plasma—that slams into Earth like a giant, wet electric blanket. When a large ejection hits, it can generate the sorts of electrical surges that power-company executives have nightmares about. In 1989, geomagnetic currents took down Hydro-Québec, blacking out the entire province of Quebec for nine hours. Had the storm occurred in the summer, when many East Coast cities draw power from Hydro-Québec, New York would have suffered the same fate.

Last November, the space environment center began issuing daily updates as well as warnings when geomagnetic or solar radiation storms appear imminent. The storms are rated on a scale of 1 (minor) to 5 (extreme)—enabling power company execs to prepare accordingly.

At the height where spacecraft orbit, solar radiation can be so intense that, during certain kinds of space-weather storms, astronauts could be endangered were they to leave the ship. Even at 35,000 feet—the average altitude at which commercial airplanes fly—Earth's magnetic field doesn't always provide adequate protection against solar radiation.

During an S3, or "strong," solar-radiation storm, passengers and crew in a commercial jet receive the equivalent of about one X ray's worth of radiation per hour. But in an S5 storm that level can jump to 100 X rays an hour. (An S5 storm occurs approximately once every 11-year cycle; S3 storms are more common, as frequent as 10 per cycle.) The vast majority of travelers don't fly high enough, long enough, or often enough, to warrant losing sleep over solar radiation. But airline pilots and flight attendants do. Since May, all 27 European airlines have been required to inform their employees about the lifetime risk of radiation exposure.

Airlines in the United States have yet to follow suit, even though employees' unions have urged them to do so for years. Dr. Robert J. Barish, an expert on radiation, contends that airline employees (who have been classified by the FAA as occupational radiation workers since 1990) should, like the folks at nuclear-power plants, be educated about on-the-job risks. For that matter, Barish adds, so should frequent business travelers.

"If you do an analysis of the dose allowed under law for the general public," Barish says, "that limit is reached within seventy-five thousand miles of air travel within a year. More than half a million business travelers are receiving that exposure unknowingly."

The risk to the average traveler, he points out, is "pretty trivial under ordinary conditions"—though pregnant women should be particularly cautious. Nonetheless, in the interest of public service, Barish has started up an automated phone service (877/786-3527; $3 per call) that wary travelers can dial for the latest official space-weather conditions. Most of the time there's no reason to worry, but if a solar storm is brewing, he says, consider hanging out in the lounge for a couple of extra hours and catching the next flight.

"I'm not trying to be sensationalistic," Barish says. "However, I would say that, for myself, given the increased risk associated with radiation levels a hundred times above normal, the best strategy is one of prudent avoidance." Apparently the strategy hasn't quite caught on. Barish says he loses $600 a month running his phone service.

Fortunately, the clouds of space weather do come with a silver lining: the aurora borealis, better known as the northern lights. When charged particles from solar wind strike Earth's magnetic field, they hit air molecules in the upper atmosphere and cause them to glow. The result appears as shimmering curtains of light—often in startling pinks and greens—that radiate from the horizon. The aurora is a hit-and-miss thing, best witnessed on cold, clear, moonless nights around the spring and autumn equinoxes; the farther north (or south, for the southern lights) you are, the better. The odds of seeing either aurora improve during periods of intense solar activity, when more particles than usual come zipping toward Earth. (In early April, a severe geomagnetic storm made the aurora visible as far south as North Carolina. These days, a good space-weatherman can often forecast an aurora hours or days in advance.)

This year, of course, promises to be a banner one for the northern lights. "Hopefully we'll see a big influx in visitors," said a lonely-sounding receptionist at the Alaska Division of Tourism. "But so far nothing—nothing extra-special."

As for tomorrow's forecast, just ask a space weatherman: "Not much out of the ordinary today," Joe Kunches says. "But all that could change. I could hang up the phone, there could be a coronal mass ejection, and in two days, away we go. So far, though, it looks like a normal day."

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