Strong solar storm could trigger northern lights in United States -

Multiple outbursts from the sun could trigger magnificent auroras, or the northern lights, in many parts of the United States this weekend, as well as potentially affect communication systems.

A severe geomagnetic storm — rated 4 out of 5 — is expected to hit Earth on Friday, per models by the National Oceanic and Atmospheric Administration. People in the United States could see moderate to strong geomagnetic activity starting at night and lasting through Saturday, although the activity won’t be as strong Saturday. If the storm ends up arriving later than expected, then Saturday could see peak geomagnetic activity.

NOAA is working with satellite and grid operators to prepare for any power or communication disruptions from the solar storm, but individuals should not have to take extraordinary measures, Shawn Dahl, the service coordinator for NOAA’s Space Weather Prediction Center, said in a news conference Friday. Instead, people can take this opportunity to look for the dancing displays of the aurora.

“The gift from space weather is the aurora,” said Rob Steenburgh, a space scientist at NOAA’s Space Weather Prediction Center. “If you happen to be in an area where it’s dark and cloud-free and relatively unpolluted by light, you may get see a fairly impressive aurora display.”

Chances of seeing the lights will be highest in the northern United States, Canada and northern Europe. At its strongest, the storm could bring aurora sightings that can be viewed with the naked eye as far south as Alabama to Northern California, according to NOAA’s Space Weather Prediction Center. Cameras, including those on cellphones, have been able to detect the aurora even farther south in recent storms.

To maximize your chances of seeing auroras Friday night, find a dark sky location away from city lights. You’ll also want cloud-free skies. Unfortunately, considerable cloud cover is predicted over the Great Lakes, Mid-Atlantic and Northeast, although some gaps in the cloud canopy are probable. Clear skies are most likely over the central states and West Coast. The storm is expected to last through the night, so an aurora could pop out in a patch of clear sky.

Geomagnetic storms are hard to forecast, and sometimes predicted northern lights displays disappoint if a storm’s timing changes or its magnetic field is out of alignment with the Earth’s. Forecasters won’t know the exact timing until around 20 to 45 minutes before storm hits Earth.

The geomagnetic storm comes when the sun is at its most active in about two decades, and it is expected to remain so for at least the rest of this year.

Auroras are created when energy and particles from the sun temporarily disturb Earth’s magnetosphere, creating a geomagnetic storm. Some solar particles travel along our planet’s magnetic field lines into the upper atmosphere, exciting nitrogen and oxygen molecules and releasing photons of light in different colors.

Friday’s anticipated geomagnetic storm is the result of multiple explosions on the sun, called coronal mass ejections. Coronal mass ejections are large clouds of solar plasma and magnetic field. Starting earlier this week, the sun has sent at least five of these eruptions toward Earth that are expected to first arrive Friday. Some have already combined, increasing the magnitude of the storm.

“There are still many [coronal mass ejections] out there, and likely more on the way,” Brent Gordon, chief of NOAA’s Space Weather Services Branch, said in Friday’s news conference. “We could see this extending through the weekend and into early next week.”

Intense geomagnetic storms can also sometimes disrupt power systems, GPS communications or satellite operations. The storm shouldn’t have a direct effect on cellphones or ATMs, but a power disruption could have secondary effects. Steenburgh and his colleagues have been working closely with grid operators across North America ahead of the storm.

The coronal mass ejections came from a particularly bustling area in the southwestern hemisphere of the sun, labeled active region 3664, Steenburgh said. Active regions are easy to see because they contain dark areas called sunspots. Sunspots are temporary dark blotches where the sun’s magnetic field is extremely strong, eventually breaking through the sun’s surface.

“These sunspot clusters emerge, and we see hundreds of them a year. But very few of them reach this size and magnetic complexity,” said Bill Murtagh, program coordinator at NOAA’s Space Weather Prediction Center. “What makes it unique here is just that it is so magnetically stressed and magnetically complex.”

The sunspot group is around 16 times the diameter of Earth, “one of the largest clusters we’ve seen in some time,” said Dahl. The size of the sunspot group is actually on par with that of the 1859 Carrington event, dubbed one of the most intense solar storms to hit Earth, but forecasters said this incoming geomagnetic storm will not be close to the same level of the Carrington storm.

If you still have your solar eclipse glasses, you can spot the large dark blotches on the lower right quadrant of the sun, although it’s rotating away from Earth.

The same sunspot group also released intense bursts of radiation known as solar flares. The sun unleashed four X-class flares — the most intense kind — since Wednesday. Solar flares can disrupt radio communications, although Murtagh said NOAA officials haven’t received any such reports as of Thursday.

In response to the flare activity, Earth experienced a minor solar radiation storm, level 1 out of 5, early on Friday. Dahl said it hasn’t caused too much concern but may affect activity by rocket launch and satellite operators.

“Usually these don’t come around a second time packing as much of a punch as they did originally,” said Dahl. “But time will tell on that.”

Jason Samenow contributed to this report.

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