Mammoth solar flare 'aimed right at Earth'

One of the most powerful solar flares in nearly 30 years erupted from the sun's surface yesterday, ejecting a titanic blast of gas, radiation and matter toward Earth.

"This one is aimed right at Earth, and it's the largest Earth-directed event we've ever seen," said John Kohl, a solar astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "This is the real thing."

Space weather forecasters said the event could lead to a geomagnetic storm today and tomorrow that could disrupt power lines and impair satellite and radio communications, although the power of the storm remained uncertain.

Solar storms occur when the protective magnetic bubble surrounding the Earth is buffeted by huge magnetic fields and streams of high-energy particles torn from the surface of the sun.

Such solar explosions are almost unimaginably violent: They can carry the power of 40 billion atom bombs, spew billions of tons of material and travel through space at speeds of 3 million miles per hour.

The storms are not harmful to people.

Yesterday's solar flare was the third largest recorded since 1976, Kohl said. The two largest flares occurred in 1989 and 2001 but caused few problems because they were pointed away from Earth.

The new flare appears to be on a collision course with our planet.

"We're going to get the full brunt of this one," said Joe Kunches, chief of the Space Weather Operations Center at the National Oceanic and Atmospheric Administration's (NOAA) Space Environment Center in Boulder, Colo.

Kunches predicted a severe geomagnetic storm rated G4 using NOAA's space-storm scale, which ranges from mild (G1) to extreme (G5). He said the storm could have periods of G5 storming.

G5 storms are capable of rendering satellites useless and disrupting communications and navigation systems.

Storms in the past 15 years have knocked out power grids and disabled satellites, leaving pagers, automatic-teller machines and some airline communications crippled.

The flare is 100 times stronger than the solar flare that reached Earth last week and did little damage. A solar storm in March 1989 that knocked out power throughout the province of Quebec was a result of the fourth most powerful flare recorded.

The impact of the storm could be less serious than expected because forecasters cannot determine the size of the magnetic field heading to Earth or its orientation — two factors that influence the destructive power of a storm, Kunches said.

In addition, those who manage power grids, maintain satellites and route aircraft have become more sophisticated and now take steps to reduce risks during extreme events, he said.

The astronauts aboard the International Space Station, for example, have already moved into the most shielded portion of the station and will remain there until all health radiation threats have passed.

And federal researchers said they already have turned off instruments and taken other precautions with science satellites.

In Southern California, wildfires already have knocked out many microwave communication antennas on the ground, making satellite communications important to emergency efforts. Researchers said safety personnel might encounter communications interference.

A positive note: Strong geomagnetic storms can produce colorful auroras in the night sky visible as far south as Texas and Florida beginning late tonight.

Normally the Earth's magnetic field deflects charged particles that hit from the sun, channeling them toward the North and South poles, where some can penetrate and interact with the atmosphere to cause the colorful auroras.

But the blasts of particles that come to Earth after solar flares often bring magnetic fields of their own, which, if oriented just right, can disrupt Earth's field, creating a temporary hole where the particles can filter in. Then those in lower latitudes get a chance to see the auroras.

The number of sunspots and solar flares waxes and wanes in an 11-year cycle that peaked in 2001. But last week two new sunspots appeared and then these flares erupted, surprising scientists by coming late in the cycle.

Scientists compared the latest flare to the "Bastille Day storm" that occurred in July 2000.

"The Bastille Day storm produced considerable disruption to both ground and space high-tech systems," said Bill Murtagh, a space weather forecaster for the NOAA.

Material from Knight-Ridder Newspapers and The Associated Press is included in this report.