Sun Shoots Monster Flare at Earth
The latest in a series of eruptions is the biggest to head our way since '89; power grids, satellites brace for the blast
Oct. 28, 2003
By Robert Roy Britt
SPACE.COM
The sun on Tuesday unleashed what appears to be the third most powerful flare in recorded history, a storm of charged particles that could hit Earth midday Wednesday with more effect than any since 1989, when power was knocked out to an entire Canadian province.
Depending On the storms magnetic orientation, it could set off a dramatic display of colorful northern lights well into midlatitudes of the United States and Europe.
Meanwhile, satellite operators and power grid managers are preparing to endure a potentially damaging event. And astronauts aboard the international space station have taken cover from heavier radiation sent out by the flare. They are not expected to be in any serious danger.
Kicked up at 6 a.m. ET Tuesday, the major solar eruption comes 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.
Tuesdays eruption is classified as an X18, 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 today may be the third strongest X-flare on record, said Paal Brekke, the European Space Agencys deputy project scientist for the Solar and Heliospheric Observatory, which first spotted the event.
A slightly stronger flare on April 2, 2001 was not pointed at Earth. Tuesdays storm is headed directly at us and could generate fantastic colorful lights in the atmosphere, known as auroras. The storm associated with the flare is called a coronal mass ejection, an expanding bubble of charged particles that race outward.
COMING FAST
The storm is traveling quicker than most and is forecast to arrive about 30 hours after it left the sun, Joe Kunches, lead forecaster at the National Oceanic and Atmospheric Administrations Space Environment Center, said in a telephone interview. That would put the arrival at about noon ET Wednesday.
Thats when it starts, Kunches said. But the storm will blow through over several hours, he said, and wont be done for up to two days.
We may be in for some great aurora, Brekke said.
Auroras are created when the charged solar particles stream down Earths magnetic field lines and excite oxygen and nitrogen atoms in the atmosphere. Normally, the auroras are only visible from place near the poles, like Alaska. But when Earths magnetic field is overwhelmed, auroras can become visible well into the United States and Europe.
For U.S. residents, Wednesday evening could provide the best chance to see auroras.
POTENTIAL THREAT
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 power grid operators arrange for less switching and fewer large-scale power swaps.
Nobody can say in advance what will happen, though, because the result depends on the orientation of Earths magnetic field in relation to that of the storm.
Until we know the orientation of the magnetic field in this [storm] cloud we wont 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.
The space storm is intrinsically stronger than one on March 6, 1989, that tripped a power grid in Quebec, Canada.
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 that the oncoming 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.
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.
ASTRONAUTS TAKE COVER
Tuesdays 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 8 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 was 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. ET Tuesday and continuing through 1:45 p.m. ET, 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 specific times, all in ET, are 9:35 to 9:55 a.m., 10:20 to 10:45 a.m., 11:50 a.m. to 12:15 p.m. and 1:25 to 1:45 p.m.
The times coincide with when the stations orbit takes it to the farthest north and south points from the equator, areas where Earths magnetic fields provide the least amount of natural protection from the suns fury.
The crew has seen some higher levels of radiation, so thats exactly why they do this, NASA spokesman Kyle Herring said. The flight surgeons monitor this very, very closely.
Increased solar activity also prompted the Expedition 2 and Expedition 3 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 7 is not as safe as many people think, even though it has a heat shield, Herring said. The Soyuz craft that brought Foale and Kaleri into space remains docked to the station as an emergency lifeboat.
The Soyuz offers probably the least amount of protection, Herring said.
Jim Banke, senior producer at Space.coms Cape Canaveral Bureau, contributed to this report.
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