Earth is currently weathering the largest solar storm recorded in more than eight years, thanks to a giant wave of charged particles from the sun that slammed into the planet's magnetic field Tuesday morning. (See pictures of auroras generated by the solar storm.)
In the early hours on Monday, NASA's Solar Dynamics Observatory caught an extreme ultraviolet flash from a solar flare, which was followed by a giant coronal mass ejection, or CME—a cloud of superheated gas and charged particles hurled off the sun.
The cloud headed toward Earth at a speed of about three million miles (4.8 million kilometers) an hour, reaching the planet a mere 35 hours after it had been unleashed.
Watch NASA video of the solar flare and CME:
When CMEs strike Earth, the charged particles pummel our planet's protective magnetic field, causing geomagnetic storms that can trigger brilliant auroras. Sky-watchers in Scandinavia, Alaska, and Canada are already reporting a surge in the northern lights, with the strongest activity expected tonight.
But intense solar storms can also cause electrical disruptions to power grids, damage orbiting satellites, and interfere with GPS signals, radio communications, and even airline flights.
"Because the initial solar flare was measured to be quite strong, it produced a substantial wave of solar radiation, the likes of which has not seen since October 2003," said Bill Murtagh, senior forecaster for NOAA's Space Weather Prediction Center in Boulder, Colorado.
"The solar radiation is currently at strong levels, and [such storms] typically persist for at least for a day or two until the entire storm passes Earth," he added.
"At this point, we have reports of sporadic radio-communication blackouts in high-latitude regions, which has led to the rerouting of some polar airline flights."
Why Solar Storms Impact Polar Flights
Airlines conducting flights across the polar regions are particularly concerned about solar storms, because particles from CMEs get funneled by Earth's magnetic field so that they become concentrated around the poles.
"Because long-distance flights across the polar regions cannot always use satellite-based communication, they rely on traditional radio communication," Murtagh said.
"However, during a solar-radiation storm, there are frequently extended periods of radio blackout. Adhering to federal aviation regulations then becomes a problem, because flights are required to remain in communication at all times."
Despite the airlines' precautions, this solar storm is actually considered to be moderate and isn't expected to cause major disturbances to ground- or space-based assets, said Antti Pulkkinen, a space weather scientist at NASA's Goddard Space Flight Center in Maryland.
However, the storm could have been much worse, he said.
"The CME was big, with well over a billion tons of mass behind it barreling through interplanetary space ... so it probably had the capability of causing some damage," he said.
"We pretty much dodged a bullet, because the CME did not directly hit Earth's magnetic field, so we got lucky in that we only got a glancing blow from the storm and did not feel its full effect."
In March 1989, for example, a severe geomagnetic storm caused a massive power blackout the Canadian province of Quebec, plunging millions into darkness for nine hours.
More Sun Storms to Come
Thanks to improved computer modeling and a flotilla of sun-monitoring satellites, space weather researchers have been able to refine their forecasts to the point where they know down to mere hours when a solar storm might arrive.
"We are very pleased with how precise our predictions were for when [today's] CME would hit," Pulkkinen said. "Our models were off by a mere 13 minutes from the actual arrival time, which is quite remarkable."
The sun is currently heading toward solar maximum in 2013, when it will reach peak activity in its natural 11-year cycle. Space weather forecasters are therefore expecting a definite uptick in the power and frequency of solar storms, making such monitoring and prediction efforts all the more critical.
"As we approach 2013, we expect to see more intense solar blasts on the sun, and some of them will no doubt be directed toward Earth," Pulkkinen said.
"So we are definitely in for more of these kind of events in the near future."