If you missed the auroras that set skies aglow in red, purple and green curtains of light Friday night, it may be a long wait before seeing another display as widespread and magnificent.
“Friday night’s storm reached superstorm level, something that happens roughly one in 20 years, on average,” said Mathew Owens, a space physicist at the University of Reading. “That doesn’t necessarily mean we’ll have to wait 20 years for the next one. That’s an average rate and these things are quasi-random.”
The next one could be next week or in 50 years, he said.
Whereas auroras are typically confined near Earth’s polar regions, social media posts showed Friday night’s display was seen in all 50 states as well as rare places like Puerto Rico, the Bahamas, Italy, Austria, Mexico and India. In the Southern Hemisphere, people photographed them in Chile, Argentina, New Zealand and Australia.
“It lit up the sky globally. The world was reporting it,” said Shawn Dahl, the service coordinator for the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center.
It brought space weather scientist Liz MacDonald to tears. Light rays were forming directly above her head in eastern Washington, appearing to fan out from a single point in the sky. This rare type of aurora, called an “aurora corona,” painted half the sky red and the other half green.
“I’m watching the skies do things I never in my lifetime thought I would see from Washington,” said MacDonald, who was amazed to the see such a dynamic aurora at this latitude. “All those particles are raining down and lighting up the magnetic field lines. It was stunning.”
The show danced overhead from sunset to sunrise.
“It’s rare and we can’t tell you when it’s going to happen again,” she added. It just depends on what the sun decides to do. Lucky for aurora chasers, the sun’s surface is bustling with activity for the next few years.
Preparing for the biggest storm in 20 years
The sun gives us more than just light. It also unleashes storms.
Geomagnetic storms occur when a surge of energy and particles from the sun — often from intense eruptions on the sun’s surface — temporarily disturb Earth’s protective magnetic bubble. NOAA ranks the strength of the storms on a scale of 1 to 5, where 5 is the most extreme and most rare.
These storms can interfere with satellite systems and GPS and radio communications. They can also excite gas molecules in our upper atmosphere and release photons of light in different colors, which are the auroras.
Days ahead of time, Dahl and his NOAA colleagues predicted Friday night was going to be special. Early last week, at least five eruptions from the sun were headed toward Earth. Some were catching up to one another and combining. For the first time in 20 years, they put out a warning for a Level 4 storm — but the storm exceeded the warning.
Friday’s storms ranked as an “extreme” geomagnetic storm, reaching Level 5. The last time such a storm happened was in October 2003, which caused a blackout in Canada, power outages in Sweden and damaged transformers in South Africa.
This time around, the extreme storm didn’t seem to disrupt power or communications systems as intensely, Dahl said. He said a few places reported “voltage irregularities,” but they did not lose power. The storm did interfere with high-frequency radio systems in certain areas. As a result, some planes rerouted their paths to not pass through those zones, so their radio signals wouldn’t be disrupted. Farmers using precision GPS to navigate their tractors reported their systems were down.
Overall, Dahl considered this a huge improvement and a good test for an even bigger geomagnetic storm that might hit Earth one day.
“We’ve been taking a lot of measures since 2003 to get better at this, to come up with better ways of planning and preparedness,” Dahl said. “Lots of entities were involved and knew well ahead what was going to happen.”
Is another extreme storm on its way?
Although no one really knows for sure when the next big geomagnetic storm will strike, scientists have some clues.
Looking at records dating back 170 years, a G5 storm statistically has about a 5 percent chance of happening in any given year, said Owens, the University of Reading space physicist.
That probability could be higher for the next couple of years, though. The sun’s activity naturally ebbs and flows in 11-year periods known as the solar cycle. The sun is half way through its current cycle, and is expected to peak this year and remain fairly active for a few more.
While improbable, Dahl said an event even bigger than Friday night’s can’t be ruled out. One of the worst documented geomagnetic storms to hit Earth was the “Carrington Event” in 1859, which sent aurora as far south as the Caribbean and disrupted telegraph systems around the world.
Friday’s solar storm wasn’t even close to size or impact of the Carrington event which only happens about once every 500 years. But storms half as intense happen about every 50 years.
“Even though it’s unlikely, we’ll still be at the highest risk for similar storms [to Friday night] or potentially even a greater one,” Dahl said. “We are overdue for an event more similar to the Carrington level of storms.”
A plethora of data — in the form of photos
For the most part, Friday’s extreme storm gave many people the chance to appreciate the aurora and to cross an item off their bucket lists. Thousands of images were snapped but those photos are more than just keepsakes, they also have scientific value.
Darrin Dressler was in bed when he saw social media posts showing the beautiful aurora displays. He was tired, but he knew he had to venture out for this rare storm. He drove an hour outside of Kansas City to a conservation area.
Green, gold and purple light rays flowed above his head, moving through the sky and changing shape.
“I’ve never thought I’d live to see a river of light flowing through the night sky,” Dressler said. “To be there and to witness it, you felt really small in one way.”
Since the October 2003 geomagnetic storm, the proliferation of cameras — mostly because of smartphones — has vastly increased aurora photography. Cameras are much more sensitive to light than our eyes and can detect auroras where they’re invisible to people. What may appear as a faint red to us becomes shades of pink, purple and reds in the camera lens. During this storm, people used their cameras to view the lights much further south than NOAA predicted they would be visible.
MacDonald founded an aurora reporting site called Aurorasaurus.org, which collects user-submitted photos for scientific research (and welcomes submissions well after an event). The photos can help researchers learn more about rare forms of the aurora as well as improve models showing where the lights can be detected. Previous studies analyzing the data have already helped refine where auroras can be seen.
“There’s still tons of science to understand here, especially with such a rare storm and being our first opportunity with such widespread imaging,” MacDonald said.
