The Sun is on the verge of an important event: changes in the magnetic field. This event occurs approximately every 11 years and marks an important phase in the solar cycle. The polarity change marks the middle of the solar maximum, the peak of solar activity, and the beginning of the transition to solar minimum. The Sun’s magnetic field last changed at the end of 2013. So what causes this polarity reversal and is it dangerous? Let’s take a deeper look at the Sun’s changing magnetic field and examine its effects on Earth.

To understand magnetic field reversal, it is important to first know the solar cycle. The roughly 11-year cycle of solar activity is governed by the Sun’s magnetic field and is indicated by the frequency and intensity of sunspots visible on the surface. The peak of solar activity during a particular solar cycle is known as a solar maximum and is currently predicted to occur between late 2024 and early 2026.

But there is another, less well-known, but very important cycle that encompasses two 11-year solar cycles. This magnetic cycle, known as the Hale cycle, lasts about 22 years, during which the Sun’s magnetic field changes and then returns to its original state, Space.com contributor and solar astrophysicist Ryan French told Space.com.

During solar minimum, the Sun’s magnetic field is close to a dipole with a north and south pole, similar to the Earth’s magnetic field. However, as we move toward solar maximum, “the Sun’s magnetic field becomes more complex, with no clear distinction between the north and south poles,” French said. When solar maximum passes and solar minimum occurs, the sun returns to the dipole, albeit with opposite polarity.

Future polar reversals will occur from a north to south magnetic field in the Northern Hemisphere and vice versa in the Southern Hemisphere. “This would result in a magnetic orientation similar to Earth, which has a southern magnetic field in the Northern Hemisphere,” French explained.

What causes polarity reversal?

The inversion occurs due to sunspots, magnetically complex regions on the Sun’s surface that can produce significant solar events (large explosions of plasma and magnetic fields) such as solar flares and coronal mass ejections (CMEs). Because sunspots appear closer to the equator, they will have an orientation that matches the old magnetic field, while sunspots that form closer to the poles will have a magnetic field that matches the incoming magnetic orientation, French said. This is called the Hale Law.

“The magnetic field from the active regions moves towards the poles and eventually causes a change” — I told Space.com before Solar physicist Todd Huxema is director of the Wilcox Solar Observatory at Stanford University.

However, the exact root cause of this pole shift remains a mystery. “Included in integrity [сонячний] “I wonder what this cycle is,” Stanford University solar physicist Phil Scherrer previously told Space.com. “We still don’t really have a coherent mathematical explanation for what’s going on.” And you don’t really understand it until you model it; “It’s really hard to understand.”

It really depends on where the magnetic field is coming from. “Will there be a lot of sunspots? So, will sunspots affect the pole’s magnetic field, or will they disappear locally?” Hoeksema said. “We don’t know how to answer this question yet.”

How fast is switching?

We know that the change in the sun’s magnetic field does not occur suddenly. This is a gradual transition from dipole to complex magnetic field to reverse dipole over the 11-year solar cycle. “In short, there is no specific ‘moment’ when the Sun’s poles reverse,” French said. said. “This is not like on Earth, where confusion is measured by the migration of the North/South Poles.”

Generally it takes a year or two for a full return, but it can vary greatly. For example, the 24th solar cycle, which ended in December 2019, took almost five years for the north polar field to reverse, according to the National Solar Observatory.

The change in the magnetic field is so gradual that you won’t even notice when it happens. And no, as dramatic as it sounds, this is not a sign of impending doom. “The world will not end tomorrow,” Scherrer previously told Space.com. However, we will experience some side effects of the polarity reversal.

How does the Sun’s magnetic rotation affect us?

There is no doubt that the Sun has been incredibly active lately, causing numerous powerful solar flares and CMEs, causing severe geomagnetic storms on Earth, which have in turn caused incredible aurora shows lately.

However, the strengthening of space weather is not the direct cause of the polar reversal. Instead, these events tend to occur together, Hoeksema told Space.com in 2013. According to French, space weather is generally strongest during solar maximum, when the Sun’s magnetic field is also at its most complex.

One side effect of the magnetic field shift is small but primarily beneficial: It can help protect the Earth from galactic cosmic rays, high-energy subatomic particles that travel at close to the speed of light and can damage the protective atmosphere outside. of the earth.

As the Sun’s magnetic field changes, the “jet layer” — a stretched surface that extends billions of miles from the Sun’s equator — becomes highly undulated, creating a better barrier to cosmic rays.

Predicting the strength of the future solar cycle

Scientists will closely monitor the change in the Sun’s magnetic field and see how long it takes for it to return to its dipole configuration. If this happens in the next few years, the next 11-year cycle will be relatively active, but if accumulation is slow, the cycle will be relatively weak, just like the previous 24-year solar cycle.