The Sun is preparing to reverse the polarity of its magnetic field, and this event is already generating many news stories and speculations. Let’s explore the potential risks and implications of this phenomenon for humanity.
This fascinating process is a key phase of the solar cycle, which occurs roughly every 11 years. When the magnetic field’s polarity reverses, it represents the middle of the sun’s highest activity. Importantly, this is not a rare event, like a comet passing by the planet. It was last seen in 2013 when it also received significant media attention. Given this, we need to understand what this phenomenon brings to our planet and whether it is dangerous.
The Nature of the Changes
The key concept we need to explore is the solar cycle, which lasts about 11 years. It is defined by several factors, including the sun’s overall activity and the appearance of sunspots on its surface.
The solar maximum is the peak period when the cycle’s activity is at its highest. According to forecasts, the next peak in solar activity will occur between late 2024 and early 2026.
There’s also a longer cycle known as the Hale cycle, which spans 22 years, combining two 11-year solar cycles. During this time, the sun reverses its polarity twice. Astrophysicist Ryan French, who studies the Sun, noted that after the completion of a full cycle, the Sun’s magnetic field returns to its original polarity.
From a physics perspective, during the solar minimum, the sun’s magnetic field resembles a dipole with two poles — north and south, similar to Earth’s magnetic field. As the sun approaches its maximum, the field becomes more complex, and the poles are no longer easy to distinguish.
As the sun reaches its maximum activity, it transitions back to a minimum phase, and the magnetic field once again becomes a dipole, but with reversed polarity. The northern magnetic pole will shift to the south, and the southern magnetic pole will move to the north.
Why does the polarity change?
It’s interesting that sunspots are responsible for this phenomenon. These are regions with unusual magnetic structures that can lead to intense solar flares and coronal mass ejections. Sunspots adhere to the previous magnetic field when they manifest near the equator. When they appear closer to the poles, they align with the new magnetic field, a pattern described by Hale’s law.
“Active magnetic zones move toward the poles, causing the polarity to reverse,” explained Todd Hoeksema, a leading solar physicist and director of the Wilcox Solar Observatory at Stanford University.
Mysteries of Polarity Reversal
Although we have some understanding of the process, much about it remains mysterious. “This is part of the overall solar cycle, and we’d really like to deepen our knowledge in this area,” noted physicist Phil Scherrer from Stanford. “Without building a comprehensive mathematical model of the process, our understanding will remain incomplete.”
The source of the magnetic field remains a mystery. “We pay close attention to the number and other characteristics of sunspots. Do they reflect the overall magnetic structure of the poles, or will their impact be limited to local areas?” wonders Hoeksema.
It’s important to note that the reversal of the magnetic field doesn’t happen instantly; it’s a long and gradual process that spans 11 years. As French pointed out, there is no specific moment when the poles flip—it happens sequentially, which is very different from the rapid pole shifts on Earth.
Usually, the sun’s full pole reversal takes one to two years, but this can vary. For example, according to the National Solar Observatory, the reversal of the polar field during the 24th solar cycle, which ended in December 2019, took nearly five years.
Because the field changes gradually, it’s difficult to track without specialized equipment. However, there’s no need to fear catastrophic events on Earth as a result of this process. Nevertheless, the reversal of polarity will have some consequences.
How Will the Magnetic Field Change Affect Earth?
The Sun is currently exhibiting significant activity, with frequent coronal mass ejections and intense solar flares. These phenomena trigger geomagnetic storms on Earth, which is why we’ve recently seen spectacular auroras, sometimes in places where they’re rarely observed.
Among the numerous effects of the changing solar magnetic field, one small but significant benefit stands out: Earth’s protection from galactic cosmic rays improves. These high-energy subatomic particles, traveling at nearly the speed of light, can damage spacecraft and pose risks to astronauts.
On Earth, our atmosphere protects us from these dangers. When the Sun’s magnetic field reverses, the “current sheet”—a vast surface stretching billions of miles from the solar equator—warps. This helps shield both technology and people from cosmic rays.
Researchers are closely monitoring changes in the sun’s magnetic field, and they will track the timing of its return to a dipole configuration. If this occurs in the coming years, the next 11-year solar cycle will be active. However, a delay in the process could make the new cycle weak, akin to the 24th solar cycle.