The fastest moving solar storm in years has caused a beautiful green and purple aurora

In Finland, “the aurora borealis did a spectacular dance just after dark,” self-described “aurora hunter” Alexander Kuznetsov wrote. SpaceWeather.com. “It started as a sharp dancing arc on the southern horizon, and quickly moved upward, creating some of the most vibrant red and purple aurora I have ever seen in my entire aurora hunting career!”

Matti Helin, another aurora observer in southwestern Finland, He said The “beautiful show” only lasted 20 minutes.

The powerful solar storm and spectacular light shows come as the sun reaches its zenith in two decades. Scientists expect more auroral activity in the following years, including the coming months.

Intense explosions on the sun

The aurora begins when the Sun sends a wave of solar particles toward Earth and disturbs our magnetic field, creating a geomagnetic storm. Solar particles excite oxygen and nitrogen molecules in the upper atmosphere and release photons of light, which we see as auroras.

Geomagnetic storms are rated on a scale from 1 (minor) to 5 (severe) by NOAA's Space Weather Prediction Center. On Sunday, the geomagnetic storm reached G4 level but weakened to G2 and G1 levels a few hours later.

A rapid stream of solar particles continued to batter Earth's magnetic field Monday morning, still moving at twice its normal speed. Bill Murtagh, program coordinator for the National Oceanic and Atmospheric Administration's (NOAA) Space Weather Prediction Center, said the chance of strong aurora activity was reduced due to weak geomagnetic activity.

The best crepuscular displays occurred in parts of Europe and the Southern Hemisphere, when G4 activity coincided with evening or night. Unfortunately, G4 conditions occurred during the day for the United States, when our sun blocked out the light show, but northern parts of the country still saw some dancing lights during the weaker geomagnetic storm at night.

New Zealand, as it was before dawn when the solar storm hit, was in a good location to view the aurora borealis.

“While clouds interfered with the view, the aurora borealis was strong despite the full moon,” Ian Griffin, a photographer on New Zealand's Otago Peninsula, wrote on his website. SpaceWeather.com.

Scientists tracked geomagnetic activity to a group of sunspots, or dark, cooler areas of the sun, last week. Sunspots are areas where the Sun's magnetic field is very strong. Murtagh said magnetic field lines near sunspots often tangle, intersect and realign until pressure builds up and causes a large release of energy.

Activity flared around the sunspot on Friday evening. One event was an impressive solar flare, which sent an intense wave of electromagnetic radiation to Earth. The solar flare lasted several hours and affected radio communications, according to a space weather scientist Tamitha Skov.

Murtagh said that at about the same time, another explosion occurred on the surface of the sun. The eruption, or coronal mass ejection, radiated from the center of the sun and sent a wave of solar particles straight toward Earth. The explosion was moving Incredibly fast Murtagh said that the speed of the volcano reached about 1.7 million miles per hour, and it reached Earth about 10 hours earlier than expected, which is the fastest-moving eruption in the current solar cycle.

“When we calculated how fast [the eruption] “It took just over 37 hours to get from the sun to the Earth,” Murtagh said. Anytime we see anything under 40 hours, it's too fast.

Why did aurora activity diminish so quickly?

But even a powerful direct hit from a fast-moving coronal mass ejection is not enough to guarantee a beautiful aurora propagation. The magnetic direction of a coronal mass ejection must also be exactly parallel to Earth for a strong connection, like clicking two magnetic bars together.

“We often talk about the magnetic direction of [coronal mass ejection]”How it couples with the Earth's magnetic field,” Murtagh said. “What we saw was a strong reaction initially… but that lasted for a relatively short period.”

The onset wave of a coronal mass ejection is strongly coupled to Earth's magnetic field, and emerges in a strong southerly direction to contact Earth – registered as a G4 storm. Where the sky was dark, people could see the beautiful aurora borealis. Murtagh also received reports from grid operators from British Columbia to Quebec, who reported voltage irregularities but managed them.

But as the bulk of the coronal mass reached Earth hours later, the magnetic direction flipped, just like a baseball spinning in the air. The coronal mass ejection has now taken a more northerly direction, weakening its coupling with Earth's magnetic field. The geomagnetic storm then weakened to G1 and G2 levels overnight, Murtagh said.

Although the geomagnetic storm has weakened, some skywatchers in northern latitudes are still able to catch the dancing lights.

But if you missed Sunday's activity because you were asleep or because it was daytime, don't worry. The sun's activity ebbs and flows every 11 years or so, known as the solar cycle. Scientists expect that in the coming months the sun will reach the peak of its current solar cycle.

“Comment. There are more to come,” Murtagh said. “We will see more of these types of explosions in the coming months due to the phase of the solar cycle.”

Jason Samino contributed to this report.