Stormy Weather; When the Sun's Fury Maxes out, Earth May Take a Hit

Article excerpt

Part one in a two-part series on the Earth-sun connection.

On July 14, 1789, an angry crowd stormed the infamous Bastille prison. This act of defiance ignited a revolution that turned the streets of Paris crimson, as mobs carried aloft the guillotined heads of aristocrats.

This past July 14 also marked a time of horrific violence, but on a much larger scale.

At 5:03 a.m. eastern time, a region on the sun large enough to swallow Earth suddenly became 10 times brighter, firing a torrent of high-energy radiation into space. Then, the sun, s outer atmosphere belched a billion-ton cloud of magnetized, charged particles. Traveling more than 6 million kilometers an hour, the magnetic cloud headed straight for Earth.

Twenty-five hours later, the cloud hurtled past the Solar and Heliospheric: Observatory (SOHO), a European Space Agency-NASA satellite that continuously monitors the sun. One of the craft's solar panels--its power source--suffered in seconds as much damage as it normally accrues in a year's exposure to the harsh environment of space. Another craft, NASA's flagship X-ray observatory, Chandra, was forced into hibernation.

The cloud also temporarily knocked out the sun sensor on a satellite that measures the solar wind, the breeze of charged particles that blows out from the sun. Operating blind, the craft didn't know where to point for several days.

ASCA, a Japanese X-ray satellite, was even less lucky. Accelerated by the cloud, charged particles fried the craft's flight computer, spinning ASCA out of control. The craft never regained power. Reduced to a frozen piece of space junk, ASCA will later this year crash into Earth's atmosphere.

About 26 hours after it shot out from the sun, the cloud reached Earth. Ramming into the magnetosphere, the invisible magnetic shield that surrounds our planet, the storm revved up charged particles and dumped the equivalent of 1,500 gigawatts of power into the atmosphere. That's four times the power generated by the U.S. power grid. The disturbance severely damaged two large power transformers and disturbed electric power systems, shutting down voltage-regulating devices all along the East Coast.

Scientists forecast storms as severe, or even worse, over the next 2 years.

Welcome to solar maximum.

Like Earth's magnetic field, the magnetic field of the sun has a north pole and a south pole. But every 11 years, those poles reverse direction--with great commotion. The peak of that activity is called the solar maximum, which scientists determine by counting the dark blotches on the sun, where bundles of magnetic field lines concentrate. The number of these sunspots appears to have peaked last summer, more than 6 months later than researchers had predicted. The peak, however, is a broad one, and the solar maximum is expected to last for another 18 months.

Until the Bastille Day event, this solar maximum--the 23rd on record--seemed relatively puny. Even now, after solar storms pummeled Earth twice last November, it isn't likely to stand out as one of the strongest, says forecaster Ernest Hildner, director of the National Oceanic and Atmospheric Administration's Space Environment Center in Boulder, Colo. But in two other respects, he notes, this solar cycle is like no other.

With 2,000 communications satellites launched since the last solar maximum, astronauts taking longer trips in space, and a society ever more dependent on computers, cell phones, automated banking systems, and other electronic equipment, Earth has never been as vulnerable to the havoc that an electric disturbance from the sun can wreak.

In May 1998, for instance, a communications satellite called Galaxy IV abruptly failed. Although the cause of the failure is not known definitively, it occurred just after an unusually intense period of solar activity. When the satellite went belly-up, 45 million pagers suddenly went dead. …