Huge flares and eruptions from the sun can cause space weather, and stormy space weather can disrupt everything from satellites to the power grid to aircraft communications. Now, however, there is good news for people monitoring the phenomenon – the sun has gone from one of its 11-year activity cycles to another, and scientists predict that the new cycle should be as calm as the last.
However, this does not mean zero risk of extreme weather events. Even in the last, relatively weak solar cycle, drama on the sun occasionally triggered weirdness on Earth such as radio blackouts, disruptions to air traffic control, power outages – and even beautiful aurorae seen as far south as Alabama.
Over each solar cycle, the sloping sun moves from a relatively quiet period through a much more active one. Scientists monitor all this activity by keeping an eye on the number of sunspots, temporary dark spots on the surface of the sun. These spots are associated with solar activity such as giant explosions that send light, energy and solar material into space.
Counting sunspots goes back centuries, and the list of numbered solar cycles tracked by scientists starts with one that began in 1755 and ended in 1766. On average, cycles last about 11 years.
Based on recent data on sunspots, researchers can now say that the so-called “Solar Cycle 24” ended in December 2019. Solar Cycle 25 has officially begun, where the number of sunspots is slowly but steadily increasing.
A panel of international experts convened by NASA and the National Oceanic and Atmospheric Administration has predicted that this cycle will reach its peak in July 2025, and the intensity should be almost identical to the previous cycle, which was not very strong.
“The last cycle, solar cycle 24, was the fourth smallest cycle recorded and the weakest cycle in 100 years,” said Lisa Upton, solar scientist at Space Systems Research Corporation and co-chair of the Solar Cycle 25 Prediction Panel.
The expert panel quickly agreed on the forecast for the next cycle. “The consensus was very solid,” said Doug Biesecker, a solar physicist at NOAA’s Space Weather Prediction Center in Boulder, Colo., Who also co-chaired.
He says solar cycle modeling has improved over the last decade or so, making it easier to predict. But still, last time, the group did not go so badly.
“We were very close to predicting solar cycle 24. That was within what we consider to be our fault field on a sunspot number of plus or minus ten,” Biesecker says. “We got the timing too maximum wrong. And the reason for that was because we treated the sun like a big gas sphere, but the hemispheres south and north behave independently. The last solar cycle they were out of phase with each other more than ever before, which kind of ruined our forecast a bit. “
In addition to the obvious need to protect the power grid and other important technological infrastructures, officials will also understand space weather when trying to bring people back to the moon.
“A trip to the moon can include periods when our astronauts will not be protected from space by the Earth’s magnetic field,” said Jake Bleacher, chief research researcher at NASA’s Human Exploration and Operations Mission Directorate. “Like here at home, when you travel anywhere, you have to check the weather report, right? You have to know what to expect.”