by Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on exciting discoveries, scientific advances and more.
Colorful auroras could soon be visible again over parts of the United States – including northern and upper Midwestern states from New York to Idaho – due to a solar storm that could disrupt the Earth, according to the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center.
The center, a division of the National Weather Service, issued a new geomagnetic storm watch, known as G2, for Friday and Saturday. Unlike the G5, or major geomagnetic storm, that occurred on May 10, storm watches are not uncommon, according to the center.
But the solar flares that cause the aurora and the coronal mass ejections that are currently pouring from the sun are the result of the same sunspots that triggered solar activity in May, according to Dr Ryan French, a solar physicist at the Observatory National Solar in Boulder, Colorado.
Coronal mass ejections are large clouds of ionized gas called plasma and magnetic fields that erupt from the sun’s outer atmosphere. When these outbursts are directed at Earth, they can cause geomagnetic storms, or large disturbances in the Earth’s magnetic field.
As the sun approaches solar maximum – the peak of its 11-year cycle, which is expected this year – it becomes more active, and researchers are noticing increasingly intense solar flares erupting from the fiery orbit.
The increased activity of the sun causes auroras that dance around the Earth’s poles, known as the northern lights, or aurora borealis, and southern lights, or aurora australis. When the energetic particles from the coronal mass ejections reach the Earth’s magnetic field, they interact with gases in the atmosphere to create different colored lights in the sky.
The sun rotates on its axis once every 27 days, which scientists have learned by tracking sunspots. These dark regions, some of which can reach the size of Earth or larger, are driven by the star’s strong magnetic fields which are constantly shifting.
The large, complex clusters of sunspots on the sun’s surface that were fueled by increased solar activity in May survived their rotation around the sun. The European Space Agency’s Solar Orbiter mission, which is currently studying the back of the sun, was able to monitor the progress of the sunspots while they were out of view of Earth’s telescopes.
Now, the sunspots are returning to the side of the sun facing Earth, which means that the chance for dazzling auroral displays could increase during the next week, experts say.
The birth of solar storms
While it’s typical for sunspot clusters to last two to three rotations around the sun, they typically fade after one rotation and become less active, French said.
The sunspot cluster now coming back around is still capable of producing X-class flares, the largest of solar flares, but the frequency appears to have decreased, he said.
French observed two X-class flares a day for six days in May.
“It’s probably the highest cluster of X-class flares we’ve had in decades,” French said. “This current solar cycle appears to be more active than the 2014 peak, but not as active as the 2003 peak.”
Now, the sunspots are producing flares every two days, so the frequency has gone down, and the complexity of the sunspot cluster has decreased, French said.
The Earth is predicted to be “right on the right edge” of the coronal mass extinction that is currently underway, the French said.
The sunspots will face Earth more directly between Tuesday and Thursday, the French said.
“Any larger eruptions during that time, and a few days outside of that window, could lead to a possible eruption, and there could be a geomagnetic storm,” French said. “The frequency of objects is decreasing, but you only need one to create a major geomagnetic storm. I think whether that one will be big enough to cause something similar to what we saw in mid-May is unlikely.”
Keep an eye out for auroras during the Tuesday through Thursday window as well as a few days after that, French said. The auroras could be visible to millions, but the locations depend on if any coronal mass ejections affect Earth.
A solar maximum is usually declared by a panel of experts well after it has passed, so scientists cannot say whether a solar maximum is happening right now. But an increased chance of solar activity is expected in the next two years, French said.
“The thing about solar cycles is that sometimes they have twin peaks,” said Shawn Dahl, service coordinator for the Space Weather Prediction Center. “Sometimes the southern hemisphere (the sun) or the northern hemisphere will be culminating.”
Near solar maximum, sunspots tend to cluster around the equator. But the sunspot clusters that were active in the past month were in the sun’s northern and southern hemispheres, Dahl noted.
Although scientists can track active clusters of sunspots, others may appear at any time during the period leading up to solar maximum.
“We can have a new sunspot group right in front of us,” Dahl said. “We have no way of knowing that’s going to happen until we see it. That’s exactly what it’s going to be like this year all the way through next year and even into 2026.”
Lessons learned from solar storms
May 10 was a historic storm, but thankfully it did not reach the level of the Carrington Event of 1859, which caused telegraph stations to spark and catch fire and remains the most intense geomagnetic storm ever recorded.
Before May 10, the last G5 storm to hit the Earth was in 2003, causing power outages in Sweden and damaging power transformers in South Africa.
Since then, governments have taken steps with legislation, research and operations to mitigate the negative impacts of solar storms, Dahl said.
The May 10 solar storm was the most successful space weather storm in history, Dahl said.
“All this work and preparation led to this moment, and the nation could not be more prepared for a space weather storm,” he said.
With these events, there is always the possibility of disruption to communications, the electrical power grid, navigation, and radio and satellite operations. During the storm on May 10, power grid and satellite operators kept the satellites in order and correctly in orbit and managed the build-up of intense geomagnetic currents on the grid systems.
Extreme solar storms can cause the Earth’s atmosphere to change the level of drag on satellites, making it harder for operators to keep them within their specific orbits, according to the Space Agency of Europe.
“There were a lot of effects that people don’t hear about because things got mitigated when we didn’t see as many direct impacts,” Dahl said.
For more CNN news and newsletters create an account at CNN.com
