Dazzling aurora lit up Sunday-night sky

Pulsating in red, green and purple streaks, auroras - also known as the northern lights - made a vibrant appearance across pockets of the Northern Hemisphere from Sunday night to Monday morning. Sky watchers in the United States reported the dancing colorful ribbons from Alaska, Seattle, Michigan, Upstate New York and as far south as Ohio. People also reported sightings in Alberta, Canada and northern Europe.

Space weather forecasters predict that activity will continue Monday night across portions of the United States and Europe. The activity already brought a strong geomagnetic storm Sunday night and could continue with moderate activity.

“For a big, big storm, you’ll see it pushed way far south. It’s always worth taking a look,” said Rob Steenburgh, acting lead at the Space Weather Prediction Center at the National Oceanic and Atmospheric Administration.

Steenburgh was called at 3 a.m. Monday when geomagnetic storm levels reached a level 3 out of 5, which hadn’t occurred since April. On Monday, activity is expected to decrease to a level 2 out of 5, which he said means it may not appear as far south as on Sunday.

Auroras are a visible manifestation of the sun’s impact on the Earth. They are generated during a geomagnetic storm, when a surge of energy and particles from the sun temporarily collides with Earth’s magnetosphere, an invisible magnetic shield that protects our planet from high-energy radiation and damaging solar particles. This surge of solar particles compresses the magnetosphere, changing the configuration of Earth’s magnetic field lines. Some particles get trapped along the magnetic field lines and travel into the upper atmosphere, where they excite nitrogen and oxygen molecules - releasing photons, or light that we perceive as an aurora.

In this case, the surge of energy and particles came from “a big tangled-up mess” from the sun in recent days, Steenburgh said. Over the weekend, two explosions from the sun called coronal mass ejections occurred in quick succession and made a beeline for Earth. Steenburgh said the event was made more complex by a particularly fast wind stream from the sun, known as a high-speed solar wind stream, blowing upward of 700 kilometers per second - the highest value in years, according to spaceweather.com.

When these coronal mass ejections interact with the streams, “it can make the entire thing more complex and potentially more impactful,” Steenburgh said. At least one and possibly both coronal mass ejections have impacted Earth by now, Steenburgh said. If both have impacted Earth, then he expects the geomagnetic activity to decrease to a level 2 out of 5 Monday night.

Eyewitnesses to Sunday night’s spectacle were awestruck.

“What a special night! Here are two of my good friends and co-workers witnessing their first ever Aurora! In OHIO, of all places!” MaryBeth Kiczenski wrote to spaceweather.com, who photographed the lights from the edge of Lake Erie.

In Pennsylvania, Bill Barr posted a photo of an aurora battling the moonlight. “Usually really green here but this time it was red,” Barr wrote on spaceweather.com. The colors of an aurora depend on the altitude and type of molecule that is excited. Excited oxygen atoms typically glow red above 120 miles, while green excitement occurs between 75 and 110 miles.

Mike Abramyan shared an aerial image of the aurora on Twitter taken as he flew over Buffalo around 10:45 p.m. on Sunday. Others also shared time-lapses of the dancing aurora.

After these geomagnetic storms pass, Steenburgh said, more activity could be on its way. “There’s still one more region [on the sun] that looks like it could have some potential to produce more activity,” he said.

This activity is just a preview of what’s to come, as the sun enters a period of high activity and sunspots known as the solar maximum over the next few years.

“We’re in the midst of the rise into the next solar maximum,” Steenburgh said. “This is not unexpected.”