Since Sunday, the sun has launched a barrage of flares, particle radiation and blobs of plasma that have disrupted some radio communications and forced airlines to reroute northern flights.
Scientists expected the solar storm — the most intense since 2006 — to intensify Thursday morning as the latest blast pushes past Earth.
The storm could temporarily disrupt GPS signals and stress the North American power grid, according to Yihua Zheng, a scientist at NASA’s Space Weather Laboratory, but the Earth’s magnetic field will repel much of the radiation, protecting people on the ground.
The stormy space weather started with a potent sunspot that unleashed X-class solar flares — the strongest variety — on Sunday and again Tuesday evening.
“This was the sun’s version of Super Tuesday,” said Joe Kunches, a scientist at the Space Weather Prediction Center, part of the National Oceanic and Atmospheric Administration in Boulder, Colo.
The first flare triggered a coronal mass ejection — a wave of plasma — that reached the Earth on Tuesday. The resulting geomagnetic storm rated a moderate “2” on NOAA’s five-point scale.
But as that storm lingers, a second blast, traveling at nearly 4 million mph, was set to arrive early Thursday, further hammering Earth’s distorted magnetic field.
“We’ve had these multiple shots,” Kunches said. “They can pile on top of each other, so the second one has a more energetic impact on Earth.”
Kunches said that the second wave could push the geomagnetic storm up to a G3, or “strong” rating.
Particle radiation emitted by the sun could also “cause problems to spacecraft and affect human safety in space,” Zheng said.
But NASA spokeswoman Brandy Dean said that the six people on the international space station were not planning to take any special action. The station’s shell protects against radiation, Dean said, and no spacewalks are planned for the next few days.
After a years-long quiet period, solar activity is ramping up and is expected to peak in May 2013. For reasons unknown, solar activity cycles every 11 to 12 years.
Satellite operators and power companies are keeping a close eye on the activity, Kunches said. But current space weather forecasting cannot predict the precise effect on the power grid.
“It’s like predicting five inches of rain,” Kunches said. “We know it’s going to fall, but the real question is how fast will it fall? For the power grid, they want to know how fast the Earth’s magnetic field is going to change. Unfortunately, we just don’t have the ability to give them that much information.”
Intense solar activity can damage transformers and other power grid equipment. In 1989, a strong solar storm destroyed a transformer in Quebec and left 6 million people without power for nine hours.
The flurry of solar activity has NOAA’s Space Weather Prediction Center as busy as it gets.
“[A]lmost every type of warning, alert and watch that SWPC forecasters issue were issued today,” said a note posted to its Web site on Tuesday.
All this solar storming does offer one pretty side effect: dancing auroras that could dip as far south as New York, Illinois and Oregon.