Earth escapes harm from solar storm
  A solar storm slammed into Earth’s outer atmosphere early Wednesday, but did less damage than feared because of the way the energy cloud was magnetically aligned, experts in space weather said.
The brunt of the coronal mass ejection, a cloud of electrically charged particles 13-times bigger than Earth, hit the planet’s magnetic field about 1 a.m. EST, almost 11 hours earlier than expected.
Although it was the third largest flare to reach Earth since scientists started keeping records of the events in 1976, the resulting geomagnetic storm’s most extreme impact was short-lived.
“The most dangerous part was not the strength of this flare, but that it was aimed at us. Fortunately, the magnetic orientation of this blob of energy was not aligned to cause the greatest disruption to Earth’s magnetic field,” said Sabatino Sofia, director of Yale University’s Center for Solar and Space Research.
“If they have a magnetic field pointing south, we know it interacts more violently with the Earth’s magnetosphere,” said Paal Brekke, deputy project scientist for the sun-observing SOHO spacecraft, a joint NASA/European Space Agency satellite that first spotted the flare Tuesday. “We were quite lucky.”
Rather than causing extreme fluctuations in the magnetic field for up to 24 hours, as had been feared, the most intense phase, G-5 on the National Oceanic and Atmospheric Administration’s space weather scales, lasted for only about two hours.
But Joe Kunches, senior forecaster with NOAA’s Space Environment Center in Boulder, Colo., noted Wednesday afternoon that the magnetic orientation of the continuing strong storm was shifting to a more southern field, “so it’s possible that we could ring the bell for a while again this evening.”
Kunches said although forecasters can spot solar flares headed for Earth, “we can’t tell their magnetic signature until they’re upon us. It’s like that stunt the Harlem Globetrotters used to do to the crowd in their games, running around with a bucket that might be full of water, or it might be filled with feathers. We know the bucket’s coming from the sun, but we can’t be sure of the contents with the instruments we have.”
For most Americans who happened to be up in the wee hours Wednesday under clear skies, the main effects of the storm were some spectacular displays of Northern Lights. In Alaska, where the aurora is common, observers noted an unusual reddish tint to the curtains of light. People reported seeing the lights as far south as Missouri and central California, according to NASA’s spaceweather.com Web site.
Aboard the International Space Station, American crewman Mike Foale and Russian Alexander Kaleri were told to stay within the most heavily shielded part of the spacecraft for about 20 minutes during each 90 minute orbit, when it reaches points where the Earth’s magnetic field gives them the least protection from elevated levels of radiation.
Likewise, commercial aircraft flying polar routes have either changed to more southerly tracks or flown at lower altitudes than normal to help limit radiation exposure to crew and passengers, although the dose is normally only about equivalent to a chest X-ray.
One of the biggest concerns about geomagnetic storms is that the electrically charged particles from the sun can take advantage of Earth’s weakened field to reach the surface in large numbers. When that happens, current can surge through pipelines, power lines and cables over long distances. A 1989 solar storm blacked out much of Quebec and neighboring provinces when a grid failed.
“We know from talking with some of the operators that they’ve been seeing induced currents in their lines from these storms, but they’ve been able to put the power grids in a configuration that can manage them thus far,” Kunches said.
In Tokyo, Japanese space officials reported that the Kodama communications satellite had malfunctioned and gone into a “safe mode” during the storm, but that they were still able to communicate with the spacecraft.
Radio waves and radiation from the solar storms coming out of two large patches of sunspots have also disrupted the Earth’s ionosphere for the past week. This electrically charged layer of the atmosphere is used to bounce radio transmissions over long distances around the globe and high-frequency radio signals are often blacked out when the boundary is disturbed.
“So far, there are no big scary Halloween stories out of this storm, except that this is all happening when the sun’s supposed to be going into a quiet phase of the 11 year cycle,” Kunches said. “We just saw another flare come out of the same region of the sun, so we have the potential for more effects for at least another week.”
On the Net: www.sec.noaa.gov
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