Threatening satellites and power grids, the peak solar activity arrives earlier: the highest level in 20 years | event | level

The solar activity has reached a level not seen in 20 years. In 2019, as the sun approached the lowest point of its 11 year magnetic activity cycle, NASA, the National Oceanic and Atmospheric Administration, and the International Space Environment Service gathered over a dozen scientists to predict the next peak. Now, after several years of recovery, the official predictions of the expert group seem to be inaccurate - solar activity has reached levels not seen in 20 years, and its peak may arrive next year, several months earlier than expected.

During peak activity periods, the sun releases particle storms more frequently, hitting the Earth, threatening satellites, interfering with radio transmission, and overloading the power grid. Tamitha Skov, a solar physicist at the University of Milesville in the United States, said that due to the unusually mild nature of the previous solar cycle, "we have fallen into a false sense of complacency.".

Scientists track the solar cycle by calculating sunspots. Sunspots are active flares excited by magnetic rings, with their numbers continuously increasing throughout a solar activity cycle and then decreasing to near zero levels as magnetic activity weakens. When the NASA-NOAA-ISES prediction team met in 2019, they analyzed approximately 60 different prediction models, each of which provided estimates of the number of sunspot peaks and their arrival times.

One type of model is purely based on statistics, predicting through centuries of sunspot observations. The other type relies on observable "precursors" believed to be related to the solar cycle, such as the magnetic field strength at the poles during the solar minimum. As the cycle progresses, this "seed field" becomes even stronger as its magnetic field lines are wound into a donut shape through the rotation of the sun - faster at the equator than at the poles. The third type relies on advanced computer models that work like climate models, analyzing as much observable data as possible and using physical laws to simulate the Sun's core and constantly changing magnetic field.

After a week of discussion on different methods, the group voted to reach a consensus that the monthly number of sunspots will reach a peak of approximately 115 around July 2025. This will be a relatively weak cycle, very similar to the previous cycle. However, in reality, the sun awakens faster than expected and is also more active than expected. It has 159 sunspots in July and 115 in August.

Lisa Upton, a physicist at the Southwest Institute and co chair of the group, believes that one reason for inaccurate predictions is the quality and duration of observations, which provide power for precursor and core models - most importantly, the strength of the polar magnetic field. These values mainly come from the Wilcox Solar Observatory, which can see the polar magnetic field imprints on the solar spectrum. But the telescope resolution of the observatory is relatively poor, and the field of view is limited. NASA's missions such as Firefly and Solar will bring spacecraft closer to the sun, directly detecting its polar magnetic field, but they are still in the development stage.

Other researchers suspect that there are deeper issues. The relationship between the polar magnetic field and subsequent solar activity is only derived from decades of measurement, and other factors may also be at play. The clue comes from observations led by solar physicist and deputy director of the National Center for Atmospheric Research, Scott McIntosh.

For 20 years, he and his colleagues have tracked millions of "bright spots" in extreme ultraviolet images of the Sun, which they believe are magnetic fields moving beneath the Sun's surface. These highlights seem to follow a pattern of two solar cycles: they typically appear in mid latitude regions at the beginning of the first solar cycle, and then migrate towards the equator as solar activity peaks, decreases, and peaks again. At the end of the second cycle, these bright spots suddenly disappear, which researchers refer to as the "end event.". After this event, the highlights reappeared in the mid latitude region and resumed the cycle.

McIntosh believes that the dual cycle pattern means that the potential magnetic field bands in subsequent cycles must interact with each other - sometimes leading to an increase in solar activity. He believes that the time of the end event can be used to predict this disturbance, as well as the level and time of the next solar activity peak. After observing the most recent end event in December 2021, he and his colleagues predicted that the sunspots of this cycle would reach a peak of around 184 at some point in early 2024.