As soon as the sun set Thursday, extreme weather photographer Peter Forister excitedly headed for the hills. Forecasts had suggested that recent storming on the surface of the sun could set off auroras — brilliant dancing streaks of light, also known as the northern lights — in the Lower 48 states. For the first hour or so into his night, his camera picked up pretty but rather demure purple hues in the sky, which appeared just as a white haze to the naked eye.
Then, within 30 seconds at around 11 p.m., the sky lit up with vibrant red and yellow streaks visible to the naked eye. Forister sprinted up a hill with his camera and pushed through bushes that scratched and tore up his legs, but “it didn’t matter,” he said. “It was so exciting.”
“You just step back and jaw drop and just watch the show for a few minutes,” Forister said. “It was really remarkable, like the kind of show that will make you stop and just catch your breath.”
Yet the light show wasn’t in an aurora hot spot such as Canada, Iceland or even the northern tier of the United States. This was in Shenandoah National Park in Virginia, 75 miles southwest of D.C.
Northern lights over Virginia's Shenandoah Valley last night. Towering pillars and vivid colors were visible for a few unforgettable moments.— Peter Forister ❄️💨❄️ (@forecaster25) March 24, 2023
📍 Big Meadows, @ShenandoahNPS, Virginia, USA pic.twitter.com/4ZNv7qbxUk
“It was an exceptional storm. It lasted for over 12 hours,” said Forister, who lives in Charlottesville. “Having it only half an hour from home and a show that was nearly comparable to the stuff I saw in Iceland was just absolutely crazy.”
On Thursday night, a “severe” geomagnetic storm — rated a level four out of five by the National Oceanic and Atmospheric Administration (NOAA) — brought vibrant, bright auroras as far south as Arizona, California, Oklahoma, Iowa, New Mexico and North Carolina, according to reports on Twitter. Some even reported seeing an another newly discovered aurora-like phenomenon called STEVE, or Strong Thermal Emission Velocity Enhancement.
Fun to hang out with STEVE last night #Wyoming #wywx #AuroraBorealis #northernlights #spaceweather pic.twitter.com/ckS96zJnoS— Matt Ley (@Matt_wyo) March 24, 2023
“We were not expecting that level of storm by any means,” said Bill Murtagh, program coordinator at NOAA’s Space Weather Prediction Center. “A lot of variables come into play. … It’s difficult to get people spun up for the aurora because so often things don’t work out much more often than they do.”
Thursday night, he said, was the exception. The last time a severe “G4” level storm like this occurred was 2017.
An unexpected, stealthy source from the sun
Auroras are generated during geomagnetic storms when energy and particles from the sun disturb Earth’s magnetosphere. Some particles travel along Earth’s magnetic field lines into the upper atmosphere, where they excite oxygen and nitrogen molecules and release photons of light.
Auroras are commonly seen at higher latitudes, but the strength of the storm allowed people at mid-latitudes to see them as well. But the conditions that led to this storm were rare and “almost impossible to predict,” Murtagh said.
The creation of an aurora starts when the sun sends a surge of energy and particles, often through an explosion on the sun called a coronal mass ejection. When forecasters see a coronal mass ejection directed toward Earth, they usually see the speed of the stream of solar particles increase. But that didn’t happen this time.
Dancing #AuroraBorealis pillars over Asheville captured last night at 11:15 PM... I will never forget this. pic.twitter.com/AJ8AQutaqT— Evan Fisher (@EFisherWX) March 24, 2023
OMG OMG OMG! NEW MEXICO WHAT IS LIFE ✨✨✨😭😭😭#nmwx pic.twitter.com/ynEpKhaJBt— Lauren Thompson ⚡️ (@landscapesbyLT) March 24, 2023
“When the CME hit, the solar wind speed didn’t change much,” Murtagh said. “But what we did get was this kind of perfectly aligned magnetic cloud.”
Murtagh explained: Think of the coronal mass ejection as a magnet shot out from the sun. That magnet now interacts with the Earth’s magnetic field. Like two bar magnets, the fields connected in such a way that “just opened things up.”
“The [sun’s] magnetic field coupled perfectly with Earth’s magnetic field, and the consequence was severe storming and beautiful aurora extending down into the mid-latitudes,” he said.
NASA solar physicist Alex Young agreed that this G4 storm was harder to predict than most. For one thing, the sun was shooting off several coronal mass ejections, but none of them looked as though they were headed for Earth. Intermixed with all of this activity, though, “a puff” appeared to come from the center of the sun and practically had a straight shot at Earth, he said. But it was jumbled, given the other activity, and not easily discernible in the data.
Those kinds of puffs are called stealth coronal mass ejections, which Young thinks kicked the geomagnetic activity up a notch. “We’ll probably hear more about it in days as people analyze it,” he said.
Young said we’re also in what some people loosely call “aurora season.” Auroral activity tends to pick up around the equinoxes, one of which just passed on Monday. A common explanation is that Earth’s magnetic field is aligned in an optimal position to receive charged particles from the sun, which spur geomagnetic and aurora activity. This auroral season can last for a few weeks on either side of an equinox.
More activity ahead
Phoenix FTW! #azwx #aurora pic.twitter.com/iThZvhy1eI— John Sirlin (@SirlinJohn) March 24, 2023
Forecasters are expecting additional minor to moderate activity this weekend across the northern United States and latitudes. Murtagh said the NOAA expects an increase of the solar wind speed because of a “quite extraordinary” coronal hole, a temporarily cool region on the sun where solar particles can easily escape.
He and Young doubt the upcoming aurora activity will be as impressive as Thursday night’s, or as far south. Still, aurora activity should increase in general over the next few years as the sun enters a period of high activity and sunspots known as the solar maximum.
Murtagh said this solar cycle is “is actually bigger than we expected it to be.”
People should also expect to see more interesting types of phenomena. In Thursday’s storm, some people reported a light phenomenon known as STEVE. While STEVE appears like an aurora, it is distinctly characterized as a purple ribbon of light accompanied by smaller green lights that resemble a picket fence.
Solar activity has pushed aurora activity quite far in recent months. In late February, people reported an aurora as far south as Death Valley in California.
“Space weather is only going to get more exciting,” Young said. “The opportunities for someone in Virginia or someone in Maryland to go outside and see some aurora is definitely going to increase over the next couple of years.”
In the meantime, enjoy these beautiful scenes from last night’s storm shared on Twitter across the United States and Canada:
Tonight was amazing! A night I will never forget! #mtwx #aurora #northernlights pic.twitter.com/WYo4NLmcJw— Angel Enriquez (@AngelWxman) March 24, 2023
Amazing northern lights display over #Calgary tonight#yyc #AuroraBorealis pic.twitter.com/Qrhu081YAj— Leigh McAdam (@hikebiketravel) March 24, 2023
What an epic night under the lights… and back home by midnight as clouds/fog started to close in. Incredible surprise! #northernlights #Aurora #AuroraBorealis #spaceweather #sdwx #newx #photo pic.twitter.com/ELrZ7zHIEh— Chris Allington (@chrisallingt0n) March 24, 2023
The Northern Lights put on an excellent show in Southern Ontario tonight! pic.twitter.com/KmWmKwCk3V— Jason O'Young (@jasonoyoung) March 24, 2023
It’s been a dream of mine to see auroras in real life. Went to Alaska last year and didn’t see them. Saw kp of 7.3 and drove to Lake Ontario for the most beautiful display!!! I think I shed a few tears tonight. #aurora #AuroraBorealis #ontario #buffalo #nywx pic.twitter.com/le5SytGZEi— BuffaloWeather (@weather_buffalo) March 24, 2023
Jason Samenow contributed to this report.