Untitled Updated at 7:24 a.m. EST Wednesday, Oct. 29
A major solar flare unleashed Tuesday began to punish Earth's protective magnetic field early Wednesday. The storm, perhaps the third most powerful on record, could have more effect than one in 1989 that knocked out power to an entire Canadian province.
Depending on the storm's magnetic orientation, it could set off a dramatic display of colorful Northern Lights well into mid-latitudes of the United States and Europe into early Thursday.
Already early Wednesday, the NASA-run web site Spaceweather.com reported aurora had been spotted as far south as Bishop, in central California, signaling the storm's swift arrival. Meanwhile, satellite operators and power grid managers prepared to endure a potentially damaging event. And astronauts aboard the International Space Station took cover from heavier radiation sent out by the flare. They are not expected to be in any serious danger.
"This is the real thing," said John Kohl, a solar astrophysicist at the Harvard-Smithsonian Center for Astrophysics and principal investigator for an ultraviolet imager on the Solar and Heliospheric Observatory (SOHO) spacecraft. "The eruption was positioned perfectly. It's headed straight for us like a freight train."
Historically huge
Kicked up at about 6 a.m. EST (1100 UT) Tuesday, the major solar outburst came on the heels of four other flares late last week and over the weekend. All were considered fairly severe, but the latest eruption makes the others seem like solar sneezes.
Tuesday's blast is classified as an X17, where X denotes a major flare and larger numbers are stronger. That compares to two flare-ups over the weekend that were rated less than X2.
"The flare [Tuesday] may be the third strongest X-flare on record," said Paal Brekke, deputy project scientist for the SOHO spacecraft, which first spotted the event.
A slightly stronger flare on April 2, 2001 was not pointed at Earth. This week's storm is headed directly at us. The storm associated with the flare is called a coronal mass ejection, an expanding bubble of charged particles that race outward.
The expanding blob is traveling quicker than most and is forecast to arrive with full force about 30 hours after it left the Sun, Joe Kunches, lead forecaster at NOAA's Space Environment Center, said in a telephone interview early Tuesday. That would put the arrival at about Noon EST Wednesday (1700 UT).
"That's when it starts," Kunches said. But the storm will blow through over several hours, he said, and won't be done for up to two days.
Northern Lights
"We may be in for some great aurora," Brekke said.
Aurora, also called the Southern and Northern Lights, are created when the charged solar particles stream down Earth's magnetic field lines and excite oxygen and nitrogen atoms in the atmosphere. Normally the aurora are only visible from places near the poles, like Alaska. But when Earth's magnetic field is overwhelmed, the aurora can dip will into the United States and Europe.
Wednesday evening could provide the best chance to see aurora for U.S. residents. Those in the far north may see activity endure well into Thursday and perhaps beyond. Scientists say typically the best time is between 10 a.m. and 2 a.m.
The storm is also potentially a serious threat to satellites and other communication systems, including power grids on Earth. Kunches said satellite operators and power grid managers are likely to take stringent measures to protect their assets.
Engineers can put some satellites into hibernation modes and reduce the operations of others to reduce the risk of electrical disruption. The storm, however, can swell Earth's upper atmosphere, creating drag that can pull a satellite out of orbit.
Power grid operators arrange for less switching and fewer large-scale power swaps.
The space storm is intrinsically stronger than one on March 6, 1989 that tripped a power grid in Quebec, Canada.
Lesser storms have caused satellite problems. In 1997, an AT&T Telestar 401 satellite used to broadcast television shows from networks to local affiliates was knocked out during a solar storm. In May 1998 a solar blast disabled PanAmSat's Galaxy IV. Among the casualties: automated teller machines; gas station credit card handling services; 80 percent of all pagers in the United States; news wire service feeds; CNN's airport network; and some airline weather tracking services.
Unpredictable
Nobody can say in advance what will happen, though, because the result depends on the orientation of Earth's magnetic field in relation to that of the storm. The storm's magnetic field cannot be measured until about 30 minutes before it hits.
"Until we know the orientation of the magnetic field in this [storm] cloud we won't know how severe the geomagnetic storm will be," Brekke said. "If the cloud has a southward directed magnetic field it will be severe, while if it has a northward component it will not affect us that much."
Either way, forecasters said, the aurora are likely to put on a fine display.
The greatest solar storm on record occurred in 1859, shorting out telegraph wires and starting fires in the United States and Europe. Brekke told SPACE.com this week's storm, if it hooks up with Earth in just the right way, would be about one-third as strong as the 1859 tempest. It could, he added, be either less or more powerful than the 1989 storm.
Forecasters said this week's storm is similar to one that hit in July 2000 and was dubbed the Bastille Day event. It too originated near the center of the Sun and its coronal mass ejection reached Earth relatively quickly.
"The Bastille Day storm produced considerable disruption to both ground and space high-tech systems," said NOAA forecaster Bill Murtagh.
Communication disruptions can occur without actually damaging satellites. Even cell phone towers can be zapped, causing dropped calls.
The coronal mass ejection is one in a series sent out by two huge sunspots, the largest pair to grace the Sun at one time in recent memory. Sunspot 486 was responsible for this blast. More major flares are possible in coming days, forecasters said.
Astronauts take cover
Tuesday's eruption also accelerated a high-energy proton shower. These can cause damage to satellites and can be harmful for astronauts, Brekke said. NASA is careful not to plan spacewalks during solar storms.
Aboard the International Space Station the Expedition Eight crew of Mike Foale and Alexander Kaleri adjusted their workday a bit in response to the storm. Radiation from a solar flare -- which preceded the coronal mass ejection -- arrives at light-speed and has already been detected at the orbiting outpost. Light and other radiation travels from the Sun to Earth in about 8 minutes.
Beginning at 8:49 a.m. EST Tuesday and continuing through 1:45 p.m. EST, the two-man caretaker crew confined themselves to the most heavily protected area of the station for about 20 minutes during every 90-minute orbit.
The times coincide with when the station's orbit takes it to the farthest north and south points from the equator, areas where Earth's magnetic fields provide the least amount of natural protection from the Sun's fury.
"The crew has seen some higher levels of radiation, so that's exactly why they do this," said NASA spokesman Kyle Herring. "The flight surgeons monitor this very, very closely."
Increased solar activity also prompted the Expedition Two and Expedition Three crews to take similar precautions in April and November 2001, respectively. The safest part of the station is the far end of the Russian Zvezda service module.
The Soyuz spacecraft -- one of which returned to Earth last night with the crew of Expedition Seven -- is not as safe, as many people think because it has a heat shield, Herring said. Another Soyuz spacecraft, which took Foale and Kaleri to the station, remains docked there as a lifeboat.
"The Soyuz offers probably the least amount of protection," Herring said.
-- Jim Banke, Senior Producer at SPACE.com's Cape Canaveral Bureau, contributed to this report.
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