Sun delivers yet another shot at Earth

[Balandar]

Salvo may spark more auroras

By Richard Stenger and Kate Tobin

CNN

(CNN) --As Earth's magnetic field weathered a strong solar shock wave this week, the sun unleashed another powerful flare that could herald more geomagnetic storms on Thursday.

Our planet endured the brunt of the first storm Wednesday and early Thursday, hurled Tuesday by the third most powerful solar flare ever observed, without major problems.

But late Wednesday, solar scientists observed another big solar explosion, one of the top 20 on record, accompanied by another huge stream of supercharged gas headed in our direction. It could arrive as early as Thursday afternoon.

"It's like the Earth is looking right down the barrel of a giant gun pointed at us by the sun...and it's taken two big shots at us," said John Kohl of the Harvard-Smithsonian Center for Astrophysics.

"I have not seen anything like it in my entire career as a solar physicist. The probability of this happening is so low that it is a statistical anomaly," he said in a statement Thursday.

Known as coronal mass ejections (CMEs), the solar clouds of high-energy particles and gas, when they interact with the Earth's magnetosphere, can trigger geomagnetic storms and disrupt electrical systems on Earth and in orbit.

Whether this CME shakes up the planet more or less than the previous storm depends on a variety of factors, like its magnetic alignment and whether it delivers a glancing blow or direct hit.

'It's causing interference'

Power grids in the northern United States and Canada felt the effects of the first storm. Utilities endured power surges and closely monitored their systems to prevent surges, according to NOAA.

And airplanes flying in extreme northern latitudes, mostly over the Arctic, have had minor problems with radio communications, according to Canadian aviation authorities.

But no flights have been stopped and the pilots could use backup radio systems in an emergency.

"It's causing interference, in some cases more severe than others. Overall, it is still a very manageable occurrence," said Louis Garneau, spokesman for Nav Canada, which manages Canada's civil aviation navigation service.

So far only sporadic problems have been reported in space. One or two Japanese satellites were knocked offline this weekend, possibly due to electrical problems connected with increased solar activity.

Some instruments onboard the Solar and Heliospheric Observatory (SOHO), a sun-watching satellite, have been turned off to prevent malfunctions.

Astronauts take cover

NASA has taken precautions as well with its most precious cargo, astronaut Mike Foale and Russian cosmonaut Alexander Kaleri on board the international space station.

Foale and Kaleri, the only humans currently outside the protection of Earth's atmosphere, are retreating during peak exposure times to the living quarters of the station, which provides the best radiation protection.

As a precaution, NASA shut down the station's robotic arm, which is the most exposed piece of hardware.

The solar shock waves sometimes boost the northern and southern lights, pushing them from the polar regions to the middle latitudes.

"This latest CME will sweep past our planet on October 30th or 31st and could trigger renewed geomagnetic storming. Sky watchers should be alert for auroras tonight," said NASA's Spaceweather.com on Thursday.

Observers as far south as Texas and Georgia observed auroras the night before.

Space weather forecasters say this spate of strong solar flares is not consistent with normal solar behavior. The sun, which follows an 11-year activity cycle, has been quieting down since the last peak in 2000.

CNN space Producer David Santucci contributed to this report.