It's peak time for solar storms, but based on what scientists have seen so far, the most noticeable problems on Earth will be slight degradations in GPS navigation service — and trying to decide which pictures of the northern lights are the coolest.
The sun shot out a double burst of electrically charged particles — known as coronal mass ejections, or CMEs — directly toward us this week. The first one was associated with a moderate M4.6 flare on Monday, and the second one accompanied a strong X1.6 flare on Wednesday.
The first CME encountered Earth's magnetic field on Thursday night — and the second, more energetic storm started sweeping past us on Friday, said Thomas Berger, director of the National Weather Service's Space Weather Prediction Center. That storm appears to have a northward-pointing magnetic field.
What does that mean? "It will not interact as strongly with Earth's magnetic field, as far as we can tell," Berger told NBC News.
Extremely strong solar storms have the potential to disrupt satellite communications and power grids. The prime example is the 1989 geomagnetic storm that hit so hard it left millions without electricity, caused weather satellites to go offline and sparked fears that a nuclear strike was in progress.
This double-whammy is nowhere near as strong, and the operators of power grids and satellite systems are much more prepared.
Berger said the storm could reach a strong G3 level by Saturday. That means grid operators might have to adjust the levels on their dials, and GPS signals might not be as accurate as usual. It might also be harder to lock onto a GPS reading. "But it's nothing that's unmanageable," Berger said.
Some planes that typically fly over Earth's north polar region may be following different routes for the next day or so, to avoid moderately heightened levels of solar radiation. But the radiation spike wasn't strong enough to affect operations on the International Space Station.
The storm has already generated a nice batch of photographs from northern latitudes, ranging from Scandinavia and Iceland, to Canada and Alaska, to ... Arizona? Minnesota photographer R. Michael Aguirre posted a Facebook picture of "hay bales watching the Midnight Matinee."
Even NASA astronaut Reid Weisman got in on the fun with a newly tweeted picture from the International Space Station. "Beautiful aurora are coming back," he wrote. "A welcome return indeed!"
The show is expected to get better Friday night and early Saturday as the geomagnetic activity builds. A northward-pointing storm won't produce as much of a show as a southward-pointing storm.
"We would expect to see aurora perhaps as far south as the middle of Wyoming, Idaho, and perhaps as low as Connecticut and Rhode Island, maybe even New York," Berger said. The best time to see the northern lights is after midnight, but you have to get far away from city lights. This map gives you an idea how the weather for aurora-watching is shaping up.
The sunspot region responsible for this week's twin storms, AR2158, is still capable of shooting storms our way — and experts are keeping a close watch for unusual trends in the sun's 11-year activity cycle.
"While the jury is still out, the recent solar flare suggests that the sun may still be active, albeit in an unusually quiet solar maximum," Nathan Schwandron of the University of New Hampshire's Space Science Center said in a statement. "The implications for the future of space weather currently hang in the balance. Will the sun remain in its abnormal state, or will we see the return to levels of solar activity more usual for the space age? This is the big question with which scientists are currently wrestling.”
For updated space weather forecasts, check out the Space Weather Prediction Center's home page, its Facebook page and its Ovation aurora forecast page. The University of Alaska's aurora forecast page is also a good resource. And you can count on SpaceWeather.com to provide the latest outlook as well as the greatest aurora gallery.
Got a great aurora picture to share? Let us know by including the hashtag #NBCAurora on Twitter, Instagram or Facebook. We'll pass along a sampling in a future posting. In the meantime, check out Chad Blakley's time-lapse video of auroral shows in Sweden, plus NBC News' slideshow of greatest hits from the northern lights.