lundi 23 janvier 2012

Big Solar Storm Hits Earth

The U.S. is bracing for the impact of the largest solar storm in almost a decade. Eric Holthaus joins the News Hub to discuss what to expect for travel and electrical devices. Photo: AFP / Getty Images.

The largest solar storm in almost a decade swept across Earth on Tuesday, affecting air traffic across the North Pole and radio communications, in a harbinger of fiercer outbursts from the Sun predicted for the year ahead, federal experts said.

A solar eruption late Sunday launched a cosmic tsunami of energy, in the form of charged particles, radio static and X-rays, across the 93 million miles to Earth. It was the biggest burst of speeding particles since October 2003, according to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center in Boulder, Colo.

The leading edge of this wave of energy crested over the planet on Tuesday, causing minor disruptions, NOAA officials said. Earth's own geomagnetic field normally protects the planet from all but the most powerful solar eruptions, and many electronics systems and communications links are shielded against outbursts of solar static. The kind of solar storm that worries space-weather forecasters, airlines and satellite companies is even bigger than Tuesday's.

Here Comes the Sun Storm

AFP/Getty Images

This January 19, 2012 shows the solar flare captured by the Solar Dynamics Observatory.

Still, the charged particles can cause computer glitches or temporary control malfunctions aboard some of the 860 or so satellites orbiting Earth, including Global Positioning System, or GPS, satellites. The storm surge also can cause current fluctuations along high-voltage power transmission lines.

"We are seeing impacts," said solar physicist Doug Biesecker at the Space Weather Prediction Center. "We do know that some airlines are not flying their polar routes. Spacecraft are at risk, but we would expect that satellite companies are able to handle something like this."

Delta Air Lines Inc. and United Continental Holdings Inc. said they were rerouting some transpolar flights to avoid the storm. Atlanta-based Delta said some flights to Detroit from Hong Kong, Shanghai and Seoul took a more southerly route on overnight flights, though a spokesman said planes flew faster to minimize delays. Tuesday departures from the U.S. were expected to follow similar routes. United, which operates a number of transpolar flights from Chicago and Newark airports, said it had rerouted flights between Washington and Dubai.

Cathay Pacific Airways Ltd., another regular on the routes, wasn't available for comment.

A strong solar radiation storm colliding with the earth's magnetic field forced airlines to divert some flights to avoid disruptions to aircraft communications. (Photo: AP)

Airlines occasionally reroute transpolar flights as a precaution during big solar storms, with radiation levels heightened near the poles. The region is also more prone to the disturbance of navigation and communications systems because of the convergence of magnetic field lines at the poles.

Transpolar routes provide the shortest flights between the U.S. and some parts of Asia.

A rare solar flare erupted late Sunday night resulting in a solar radiation storm today, according to NASA. It's the strongest such storm since September 2005, according to NOAA's Space Weather Prediction Center. (Photo/Video: NASA)

At the height of severe solar storms in 2003, almost daily communications blackouts required that flights be rerouted. The Federal Aviation Administration for the first time also warned pilots on polar routes to stay at lower altitudes to avoid slightly higher radiation levels.

NASA officials on Tuesday said there was no need for astronauts aboard the International Space Station to seek radiation shelter. The solar storm is expected to wane by Thursday.

In its normal, 11-year solar cycle of sunspots and flares, the Sun typically triggers thousands of such storms. This week's storm is among the more powerful, the space-weather experts said. Such storms are likely to become more frequent as the sun approaches its "solar maximum," predicted for May of next year.

"By this time next year, we expect to see a storm like this a couple more times," Mr. Biesecker said.

Write to Robert Lee Hotz at sciencejournal@wsj.com and Doug Cameron at doug.cameron@dowjones.com

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