For the first time, scientists have tracked a magnetic storm from its birth on the sun to its collision with Earth.
This unique portrait of a solar explosion may provide researchers with ways to predict such events and to eventually protect a growing list of vulnerable technologies.
Communication satellites, for example, relay everything from movies on HBO to corporate conference calls negotiating the next big business deal. Systems are being developed to use navigation satellites to land airliners with pinpoint accuracy in pea-soup fog. Storms either can disable the satellites or undercut their ability to send and receive signals through the ionosphere while the storm lasts.
On the ground, electric-utility grids can be subject to surges that can fry million-dollar transformers and black out entire regions.
At a press conference this week, researchers explained that by using a set of satellites designed to study how solar particles affect Earth's magnetosphere, they were able to watch a "magnetic cloud" grow as it left the sun Jan. 6 and sped toward Earth at more than a million miles an hour.
By the time it reached the planet Jan. 10, it had expanded to 30 million miles in diameter, touched off spectacular auroral displays, sent more than a million amps of electric current surging through the ionosphere, and may have destroyed a $200 million communications satellite and affected at least four other orbiting spacecraft, researchers say.
While individual satellites have watched similar storms with different types of sensors, "this is the first time we've had a complete set doing all of that at once," says Geoff Reeves at Los Alamos (N.M.) National Laboratory, one of several scientists using a satellite called POLAR to monitor Earth's magnetic field. Polar is one of four satellites that make up an international fleet that is feeding information to the International Solar-Terrestrial Physics program.
The ability to monitor such storms and eventually forecast their effects is becoming increasingly vital, scientists say. The sun is heading into another period of increased activity, which could peak around 2000.
"When you think of a weather report, it consists of information about what's happening now and a forecast," says Steve Maran, an astronomer at NASA's Goddard Space Flight Center in Greenbelt, Md. "We're still at the point of studying the basic science."
Still, researchers and potential customers for space-weather information met in Boulder, Colo., earlier this month to define the kinds of forecasts that would be useful and how to develop them. "We can give a kind of warning now," says Dr. Reeves. "It says: 'Things are bad now and they might get worse.' We'd like to reach the point where we can say: 'Things are bad, and here's how much worse they'll get.'"