The second of two major space storms dished out by the Sun this week plowed past Earth with no apparent further damage The sixth in an unprecedented series of strong space storms dished out by the Sun over a 10-day period plowed past Earth Thursday, apparently cutting power to 20,000 Swedish customers. The powerful series of outbursts also claimed two satellites as casualties while fueling a host of minor disruptions to radio broadcasts and airline flight plans.
Never have managers of power and communication systems been challenged to this extent. Scientists said the relatively new ability to produce accurate space weather forecasts helped keep damage to a minimum.
As of Friday morning the latest solar upheaval, among the 20 strongest on record, was subsiding. The storm's effects will likely continue, at lowering levels, through much of the day.
Bright lights known as aurora could dance above Earth into the weekend.
The bout of severe space weather may or may not mark the end of an amazing round of activity that zapped a pair of Japanese satellites, caused airlines to reroute commercial flights and forced power grid managers to reduce electricity flows. On multiple occasions, radio frequencies blacked out, affecting communications with pilots and creating static and momentary losses for other users.
During the unusual storminess, the Federal Aviation Administration tested a warning system for the first time, alerting airlines to the possibility of higher doses of radiation that passengers would receive on northerly routes.
Power was cut Thursday to about 20,000 homes in Malmoe, in southern Sweden, according to news reports. An official said the solar storm was the likely culprit. Severe space weather can reach down to the planet and induce extra current in power lines, tripping breakers.
Forecasts worked
Scientists said damage was kept at a minimum thanks to improvement in space weather forecasting over the past decade. Power grid managers and satellite operators have also gained experience -- the hard way -- in dealing with high doses of charged particles kicked up by the Sun.
"I think this proves that the warning system we have works," said Paal Brekke, deputy project scientist for the Solar and Heliospheric Observatory, run by NASA and the European Space Agency.
Sitting far out in space in a line between Earth and the Sun, SOHO provides the first pictures of the oncoming clouds of solar material that represent the bulk of space weather.
SOHO launched nearly eight years ago and has revolutionized space weather forecasting, according to scientists who produce the daily predictions.
World Series of solar storms
The salvo Thursday was generated by an X10 solar flare. In this classification scheme, all X-flares are "major," and the associated number ranks severity. An X17 flare on Oct. 28 fueled the strongest storm of the series and was among the four most powerful to hit Earth in recorded history.
Both storms reached G5, the highest level possible on a scale of geomagnetic activity.
None of the events this month achieved the power of the granddaddy of all space storms, an 1859 space hurricane that experts say was at least three times as intense as the X17 of Oct. 28.
Nonetheless, the activity surprised solar physicists, largely because they'd never seen two flares of such magnitude strike back-to-back.
Both flares also generated strong surges of protons, which arrived after the initial radiation, forcing residents of the International Space Station to retreat to the most well-protected module of the orbiting outpost several times during the week.
Each flare then hurled coronal mass ejections, or clouds of charged particles, at Earth. Not all flares generate all three events with such force. The CMEs each took about 19 hours to reach Earth, much less time than the typical two days required for a storm to traverse the 93 million miles.
"Two such powerful flares, with a proton event, and very fast coronal mass ejections and both directly [aimed] towards the Earth in two days, is very rare," Brekke said. "I have never heard of this before."
In addition, four earlier outbursts, beginning Oct. 22, gained minimal X-class rankings, still more severe than most other solar activity during the past several months. The Sun's surface remains volatile, and this remarkable October series could yet go to a seventh game, forecasters warn.
The storms' effects were fickle. One of the earlier and lesser flares apparently disabled a Japanese satellite, Midori 2, on Oct. 25. Another Japanese satellite, Kodama, was at least temporarily shut down on Oct. 29.
As of early Friday, no further casualties were reported from the latest of the six storms.
Flood amid drought
Some scientists were also surprised by the timing of rash of outbursts.
Solar activity goes in a poorly understood 11-year cycle. At a peak, the last of which occurred about two years ago, sunspots are common and flares frequent. Now, with the cycle ramping toward a minimum due in about three years, the Sun has been fairly quiet aside from this spectacle of October 2003.
"This is big activity no matter when it occurs, but its especially significant during this part of the solar cycle," said Joe Kunches, who leads the Space Environment Center, the space counterpart to the National Weather Service. Both agencies are run by the National Oceanic and Atmospheric Administration.
The Sun is no easy creature to dissect, and its activity can be counterintuitive.
Brekke said historical statistics show there are actually slightly more X-flares in this part of the solar cycle than during what's called "solar maximum."
Sky shows
During the series, colorful lights called aurora dipped to mid-latitudes several times. The so-called Northern Lights are normally seen only from regions near the pole, like Alaska or northern Scandinavia. But they were reported as far south as New Mexico, Texas and Florida.
SPACE.com's Night Sky Columnist, Joe Rao, got a rare glimpse of the eerie display Thursday evening from his workplace in Putnam County, near New York City.
"Going outside into our heavily light-polluted parking lot and by shielding my eyes from the lights, I could see a distinctive beet-red glow mounting in the northeast sky," Rao said. "I then looked directly overhead and saw what appeared to be an auroral ray dancing and slithering toward the southwest."
More auroras could be on tap for residents of the most northern U.S. states and Europe through the weekend, and possible at lower latitudes, into Saturday morning.
And the Sun may not be done.
Large sunspots -- as big or bigger than Jupiter -- still roam the face of the solar system's central star. The X-flares were produced by two sunspots that will go down in solar physics history as among the largest and most productive ever noted. Scientists could not remember the last time two spots so large graced the solar surface at the same time.
They were called Sunspot 484 and Sunspot 486.
These dark, cooler regions of the solar surface are areas of pent-up magnetic activity, caps on upwelling matter and energy that can blow at any moment.
Forecasters said more X-class flares are possible into next week, when the last of the spots will begin to rotate around to the other side of the spinning, unpredictable Sun.
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