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Busy season for sunspots is starting, meaning more auroras

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(CNN) — Now that hurricane season is winding down, a different storm season is ramping up. Originating 93 million miles away from Earth, solar storms, produced by the sun, have both stunning and potentially dangerous effects here on Earth.

"The sun provides us with life, with heat and light. But periodically it emits a blast of radiation that affects us here on Earth, and it can occur in different forms," says Bill Murtagh, program coordinator at the National Oceanic and Atmospheric Administration's Space Weather Prediction Center. "When it occurs it can affect the technology that we rely on here on Earth."

The Space Weather Prediction Center is a 24/7 operation that is constantly staring at the sun, using sensors on satellites and on Earth to look for sunspots on the sun, which at times can be as much as 10 times the size of Earth.

When those sunspots erupt, they can send a blast of energy known as solar storms toward Earth. That's when we get the gorgeous glow of the aurora borealis, or northern lights.

Aurora borealis

Astronaut Thomas Pesquet snapped this image of the aurora borealis event from space on Nov. 4. "We were treated to the strongest auroras of the entire mission, over North America and Canada," Pesquet tweeted.

The sunspots appear darker because they are cooler. They are where the magnetic field is the strongest. These magnetic field lines will sometimes cross and get tangled, eventually bursting.

There are seasons when the sun becomes more active. During this very active time, sunspots will appear on the surface of the sun and erupt more frequently.

This active season itself is somewhat predictable as the sun's magnetic field flips polarity over an 11-year cycle.

"The sun has negative and positive polarity, just like Earth," says Murtagh. "During this 11-year period it does a reversal of the polarity. So negative becomes positive and positive becomes negative. During the middle of that process and transition, that's when those sunspots emerge. So we go through a process when we are in the middle of this transition we get lots of sunspots and lots of space weather."

We have been in a period of solar minimum — the least amount of sunspots — for the last three to four years, and now we are starting to come out of that.

The busy season for sunspots is beginning, meaning more opportunities to see the northern and southern lights, which Murtagh says should peak between 2023 and 2028.

The two geomagnetic storms that occurred last week were level 3 storms; they produced stunning images from both ends of our planet.

"When the eruption does occur, the coronal mass ejections that cause the northern lights, once they leave the sun, we have the ability to detect them, measure their size and speed and predict when they are going to get here with relative success," says Murtagh.

Murtagh says the bigger eruptions are the fastest, getting to Earth in as little as 16 hours. But the smaller ones travel slower and can take several days to get here.

Forecasting geomagnetic storms on a 93 million-mile journey has its challenges, but he says forecasts are always improving.

"Some of the big ones, you can bet your mortgage on it that you will see the aurora, but the smaller ones are a little tougher for forecast," says Murtagh.


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