Southern and northern lights sweep planet in stunning display of auroras

Forecasters at the Space Weather Prediction Center in Boulder, Colo., issued warnings for a Level 4 out of 5 “severe” geomagnetic storm, which happens on average only 60 times every 11 years. The episode may have been even more intense at times, sparking auroral displays as far south as California, Arizona, Arkansas and Virginia.

“Certainly what you saw last night was the biggest in the last five years,” said Bill Murtagh, program coordinator for the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center. “We’re going to see a lot more activity like this in the next several years because we’re going to be in the maximum phase of the sunspot cycle.”

NOAA warns that geomagnetic storms of this strength can cause “possible widespread voltage control problems” on power grids and can “mistakenly trip out key assets” on protective systems. Satellites may see increased drag and, in some cases, even require minor corrective adjustments in positioning.

What caused the solar storm?

On Friday afternoon, NASA’s Solar Dynamics Observatory satellite recorded an explosion on the surface of the sun. The flare, rated an M2 on an ascending scale that climbs A, B, C, M to X, caused a radio burst on Earth eight minutes later. That clued NOAA forecasters into the fact that the energy was directed toward Earth.

The flare was followed by a coronal mass ejection (CME) — a mass of solar plasma, charged particles and magnetism — that headed directly toward Earth at speeds of roughly 1.5 million miles per hour. That interplanetary shock wave collided with Earth’s magnetic field on Sunday afternoon Eastern time, which was after dark in Europe and in the early hours of Monday in China. Brilliant apparitions of the northern lights quickly appeared.

The CME brought “severe” geomagnetic storming, stronger than what the Space Weather Prediction Center forecast when the CME left the sun Friday.

“The way this storm — this CME — connected was just perfectly connected to Earth’s magnetic field,” said Murtagh, who compared it to two bar magnets clicking with one another. “Consequently, the storming was up at the severe level versus just the moderate, maybe strong, level that we might have expected.”

Forecasting such intense storms is difficult because of a lack of real-time observations, he said. Spacecraft monitor the sun and can observe when a CME occurs. Using that data, Murtagh and his colleagues can determine if it’s headed toward Earth and when it might arrive based on measured speeds.

But once the CME leaves the sun, scientists won’t get data again on its speed, temperature, density or magnetic orientation until it passes a spacecraft about 1 million miles from Earth. At that point, the CME could get to Earth in only 15 to 30 minutes. This dearth of data, Murtagh said, significantly limits the accurate forecasting of storm intensity.

The European Space Agency is working to add another spacecraft between the sun and Earth to monitor such space weather, but it won’t launch until later this decade, Murtagh said.

This storm persisted for about 12 hours, often at severe levels. The CME was almost twice as strong as the one that brought auroras to lower latitudes in March.

Where the northern lights were seen

The first displays appeared in China, where red pillars were seen dancing over the northern horizon. Jeff Dai, who captured a photo of pink and red hues over Karamay in the Xinjiang autonomous territory, described seeing the lights as a “dream come true” in a post to SpaceWeather.com.

“Finally the red northern light appears from the north horizon at 3AM,” he wrote. “It can be see by my naked eye. As the time passes, the aurora become stronger. I notice that it appears over my head. It’s truly spectacular!”

The colors of an aurora correspond to the type and altitude of the element that is excited in Earth’s atmosphere, Murtagh explained. Excited oxygen atoms glow red above 120 miles and glow green between 60 and 120 miles. Excited nitrogen atoms below 120 miles can glow pink or purple. Murtagh said a more intense aurora is typically higher, so lower latitudes will see more red.

“The bigger storms can light up the higher altitudes, which is largely going to [excite] the oxygen causing that red,” he said. “The further you are away, down south that is, you’re going to not see the green and yellow in the lower altitudes.”

The lights then expanded across Europe — shining in Wales, Germany, Poland, France, Hungary, Russia and Ukraine.

The official Stonehenge Twitter account in Britain posted a photo of the lights hovering over the prehistoric site — complete with a shooting star.

South of the equator, the lights glowed in New Zealand and Australia, including in the states of New South Wales and Tasmania.

Once darkness settled over the Lower 48 of the United States, the northern lights ventured across the Mid-Atlantic, Plains and Great Lakes. They hovered over Shenandoah National Park in Virginia, and in Connecticut, Massachusetts, Vermont and Maine. Clouds predominated over New Hampshire. Ohio stargazers saw them, too. Some of the photos look more impressive than real life because of long camera exposures, but scores of residents reported delicate pastels visible to the naked eye.

The lights were especially vivid in Illinois and Missouri. Over the Northern Plains and Northern Tier, the display rivaled something reminiscent of Fairbanks, Alaska.

In South Dakota, a “corona” formed where the lights shimmered directly overhead.

Unsurprisingly, there were striking auroral displays in Canada.

The auroras were visible even in southern Arizona and California. Jim Tang, a storm chaser and photographer, wrote, “Aurora visible to the naked eye,” as he snapped stunning shots near Lake Topaz, on the Nevada border due east of Sacramento.

Similar photos emerged from the Mammoth Lakes region in the Sierra Nevada, at the same latitude as San Francisco. Mammoth Lakes is known for its ski industry, averaging 400 inches of snow per year.

In Arkansas, a faint glow was spotted on the northern horizon.

Aurora and meteors — in the same shot

Several photographers were lucky enough to snag both the lights and a meteor — likely tied to the ongoing Lyrid meteor shower:

Aurora state by state

Here are some more photos posted to social media, organized by state:

Alaska

Arizona

Arkansas

California

Colorado

Connecticut

Indiana

Illinois

Iowa

Kansas

Maryland

Michigan

Minnesota

Missouri

Oklahoma

New York

North Carolina

North Dakota

Pennsylvania

Texas

Utah

Virginia

Wisconsin

Wyoming