A wave of charged particles from an intense solar storm is raising alerts about airline flights and satellite operations — and raising the prospect of stunning auroral displays.
The storm began when a powerful solar flare erupted on the sun Monday, blasting a stream of charged particles toward our planet. This electromagnetic burst — called a coronal mass ejection, or CME — started hitting Earth somewhere around 10 a.m. ET Tuesday, according to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center.
Experts at the center said that solar radiation levels were at their highest point since the Halloween storms of 2003. Earlier estimates ranked the storm as the strongest since 2005 in terms of solar radiation, but Terry Onsager, a physicist at the Space Weather Prediction Center, said that when the wave of charged particles arrived, "that took it from below the 2005 event to above the 2005 event."
Bill Murtagh, the center's program coordinator, said that the outburst was forcing airlines to change routes for some of their scheduled flights. "Most of the major airlines flying polar [routes], or even some non-polar, high-altitude routes, have taken action to mitigate the effect of this storm," he told msnbc.com.
Delta Air Lines reported that it altered routes for "a handful" of flights, and that the changes added about 15 minutes to travel times. Delta spokesman Anthony Black told Reuters that solar activity "can impact your ability to communicate ... so basically, the polar routes are being flown further south than normal."
United Airlines said one flight was diverted on Monday, while American Airlines said it has seen no operational impact from the storm so far but was monitoring the situation.
As powerful as it is, the storm should have no effect on daily life for most people.
"Probably in the next 10 hours or so, people at high latitudes can see auroras," Yihua Zheng, a lead researcher at NASA's Goddard Space Flight Center, told Space.com. "This could maybe cause communication errors at the polar caps, but the magnetic activities are probably not too strong."
The auroral displays will be especially visible for people in northern latitudes where it is currently night.
"For parts of Europe already, and further points to the east, we should expect to see strong magnetic storm conditions," astrophysicist Harlan Spence, the director of the University of New Hampshire's Institute for the Study of Earth, Oceans, and Space, told Space.com. "There's a very good chance tonight that we'll be seeing some very strong auroral displays. Typically auroras occur at relatively high latitudes, but for events like this, you could get auroras down at mid- to low latitudes."
Not a direct hit
When a coronal mass ejection hits Earth, it can trigger potentially harmful geomagnetic storms as the charged particles shower down the planet's magnetic field lines. This can amp up normal displays of Earth's auroras (also known as the northern and southern lights), but a strong CME aimed directly at Earth can also cause disruptions to satellites in orbit, as well as power grids and communications infrastructures on the ground.
Monday's solar flare set off an extremely fast-moving CME, but the ejected cloud of plasma and charged particles was not directly aimed at Earth and hit the planet at an angle instead. This glancing blow would likely lessen any impacts on Earth, Zheng said. [Photos: Huge Solar Flare Sparks Major Radiation Storm]
"Earth's magnetic field served as a shield, and pretty much shielded the radiation so that it doesn't penetrate that deep," Zheng said. "It's like a car collision: head-on or off to the side. A CME is like that too. For this one, if it was a direct hit, Earth would receive a much stronger impact. This one was on an angle — toward higher latitudes and a little off the ecliptic — otherwise it would be a much stronger impact."
Several NASA satellites, including the Solar Dynamics Observatory, the Solar Heliospheric Observatory and the STEREO spacecraft, observed the massive sun storm. Data from these spacecraft were combined to help scientists create models to calculate when and where the CME was going to hit Earth.
"A CME is kind of like a space hurricane," Zheng said. "You have to predict how it will form and evolve. From the models, we can see which spacecraft will be in its path, and what will be impacted."
At the Space Weather Center, scientists reported that the CME began interacting with Earth's magnetic field at 9:31 a.m. ET. "We predicted it would arrive at 9:18 a.m., and in reality, it arrived at 9:31 a.m., so ours has a 13-minute error," Zheng said. "Usually for this kind of model, the average error is seven hours, so this is the best case."
Storm expected to subside
At NOAA's Space Weather Prediction Center, Onsager said the level of solar radiation should gradually subside — unless the sun unleashes another big coronal mass ejection. "The expectation is that it will weaken and that it will decay over the next couple of days," he told msnbc.com.
The University of New Hampshire's Spence said "the chance for re-intensification is still possible because this active spot on the sun that created the initial havoc could go off again."
The solar flare associated with this week's storm was estimated to be an M9-class eruption, which placed it teetering on the edge of being an X-class flare, the most powerful type of solar storm. M-class sun storms are powerful but midrange, while C-class flares are weaker.
The flare erupted from sunspot 1402, a region near the meridian of the sun that has been active for a while now, Zheng said. The powerful solar storm could be signaling that the sun is waking up after an extended period of relative dormancy.
The sun's activity waxes and wanes on an 11-year cycle. The star is currently in the midst of Solar Cycle 24, and activity is expected to continue ramping up toward the solar maximum in 2013.
Editor's note: If you snap an amazing photo of the auroras sparked by the solar storm, or other skywatching image, and would like to share it for a possible story or gallery, please contact managing editor Tariq Malik at .
This report includes information from msnbc.com's Alan Boyle (Twitter: ), Space.com staff writer Denise Chow (Twitter: ) and Reuters. Follow Space.com for the latest in space science and exploration news on Twitterand on .