According to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center, colorful aurora could soon reappear over parts of the United States - including the northern and upper Midwestern states from New York to Idaho - as a result of a solar storm that could hit Earth. meet.
The center, a division of the National Weather Service, has issued a modern geomagnetic storm watch, known as a G2, for Friday and Saturday. Unlike the G5, or extreme geomagnetic storm, which occurred on May 10, moderate storm warnings are not uncommon, according to the center.
But the aurora-causing solar flares and coronal mass ejections currently being emitted from the Sun are the result of the same sunspots that caused the solar activity in May, according to Dr. Ryan French, solar physicist at the National Solar Observatory 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 eruptions are aimed at Earth, they can cause geomagnetic storms or major disruptions to the Earth's magnetic field.
As the sun approaches solar maximum - the peak in its eleven-year cycle expected this year - it becomes more active, and researchers have observed increasingly intense solar flares erupting from the fiery sphere.
Increased solar activity causes auroras that dance around Earth's poles, known as the Northern Lights, or aurora borealis, and Southern Lights, or aurora australis. When the activated particles from coronal mass ejections reach 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 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 and constantly changing magnetic fields.
The large, complex clusters of sunspots on the Sun's surface that caused increased solar activity in May have survived their rotation around the Sun. The European Space Agency's Solar Orbiter mission, currently studying the far side of the Sun, was able to track 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, meaning the chances of dazzling aurora displays could increase in the coming week, experts say.
The birth of solar storms
While it's normal for sunspot clusters to survive two to three rotations around the sun, they typically decay after one rotation and become less active, French said.
The now returning sunspot cluster is still capable of producing X-class flares, the largest solar flares, but its frequency appears to have decreased, he said.
French observed two X-class eruptions per day for about six days in May.
"It's probably the highest cluster of X-class flares we've had in a few decades," French said. "This current solar cycle appears more active than the 2014 peak, but not as active as the 2003 peak."
Now the sunspots produce bursts every two days, so the frequency has dropped and the complexity of the sunspot cluster has decreased, French said.
Earth is predicted to "just reach the edge" of the coronal mass ejection currently underway, French said.
The sunspots will be pointed toward Earth in a more direct manner between Tuesday and Thursday, French said.
"Any larger eruption during that time, and a few days beyond that window, could cause an eruption our way and that could cause a geomagnetic storm," French said. "The frequency of things is decreasing, but it only takes one to create a major geomagnetic storm. Whether it will be large enough to cause something similar to what we saw in mid-May, I think is unlikely."
Keep an eye out for auroras during that Tuesday-to-Thursday window and a few days afterward, French said. The auroras can be visible to millions of people, but their location depends on whether coronal mass ejections occur on Earth.
A panel of experts usually announces the peak of the solar maximum long after it has passed, so scientists cannot tell whether the solar maximum is occurring at this time. But a greater chance of solar activity is expected in the next two years, French said.
"The problem with solar cycles is that sometimes they have kind of a double peak," said Shawn Dahl, service coordinator for the Space Weather Prediction Center. "Sometimes the Southern Hemisphere (of the Sun) or the Northern Hemisphere will peak first."
Around the peak of solar maximum, sunspots tend to gather around the equator. But the sunspot clusters that have been active over the past month were in the sun's northern and southern hemispheres, Dahl noted.
Although scientists can monitor active sunspot clusters, others can appear at any time leading up to solar maximum.
"We can see a new sunspot group appearing right in front of us," Dahl said. "We can't know this is going to happen until we see it. That is exactly how it will be over the course of this year, into next year and even into 2026."
Lessons learned from solar storms
The May 10 storm was a historic storm, but fortunately did not reach the levels of the Carrington event of 1859, which caused telegraph stations to spark and catch fire and remains the most intense geomagnetic storm on record.
Before May 10, the last G5 storm to hit Earth occurred in 2003, resulting in power outages in Sweden and damaged power transformers in South Africa.
Since then, governments have taken steps with legislation, research and operations to mitigate the potentially negative impacts of solar storms, Dahl said.
The May 10 solar storm was the most successfully weakened space weather storm in history, Dahl said.
"All this work and preparation has led to this moment, and the nation could not have been better prepared for a space weather storm," he said.
These events always have the potential to affect communications, power grids, navigation, radio and satellite operations. During the May 10 storm, power grid and satellite operators kept satellites in order and in proper orbit and managed the build-up of intense geomagnetic currents on the grid systems.
Extreme solar storms can cause Earth's atmosphere to swell, changing the level of drag satellites experience, making it harder for operators to keep them within their specific trajectories, the European Space Agency said.
"There were a lot of impacts that people won't hear about because things were successfully mitigated when we didn't see the direct impacts as much," Dahl said.
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