This year, the Sun is set to undergo an epic transformation by flipping its magnetic field, a phenomenon where its magnetic poles reverse their positions after reaching its period of peak activity.
What Drives the Sun's Magnetic Field Reversal?
Many stars and planets, such as the Earth and the Sun, possess magnetic fields. These magnetic fields, however, are not stable, as they cyclically switch during peak solar cycles.
While the poles of the Earth reverse every hundreds of thousands of years, the reversal of the Sun's magnetic field is a regular occurrence. It happens roughly every 11 years, with the shift indicating the halfway point of the height of solar activity called solar maximum and the beginning of the shift towards solar minimum.
During solar minimum, the solar magnetic field is close to a dipole with one north pole and one south pole. As the Sun shifts toward solar maximum, its magnetic field becomes more complex where there is no clear north-south pole separation. By the time solar maximum has occurred and solar minimum arrives, the Sun has returned to a dipole but with a flipped polarity.
The reversal of the Sun's magnetic field is caused by sunspots, the magnetically complex areas of its surface which can cause significant solar events. As sunspots appear close to the Sun's equator, they will have an orientation that matches the old magnetic field. Meanwhile, sunspots that form closer to the poles will have a magnetic field that matches the incoming magnetic orientation.
According to solar physicist Todd Hoeksema from the Wilcox Solar Observatory at Stanford University, the magnetic field from active areas makes its way toward the solar poles and causes the reversal. However, the exact cause of such a polar flip remains mysterious. Scientists still do not have a self-consistent mathematical description of what is really happening.
So far, what the experts know is that the solar magnetic field flip is not an instantaneous process. Instead, it is a gradual adjustment from a dipole to a complex magnetic field, to a reversed dipole over the entire 11-year solar cycle.
The last time the magnetic field of the Sun flipped happened toward the end of 2013. This means that we are just about due, and current estimates predict it will take place between late 2024 and early 2026.
READ ALSO: Sun's Magnetic Field Origins Revealed: Surface Plasma Instabilities Identified
How Will the Flip Affect Us?
The magnetic field reversal is so slow that we will not even notice when it happens. And while it sounds dramatic, it is not a sign of an impending apocalypse.
One side effect of the polarity flip is actually beneficial. It can help protect our planet from galactic cosmic rays, or the high-energy subatomic particles which can damage spacecraft and harm astronauts as they travel outside the Earth's protective atmosphere.
As the magnetic field of the Sun shifts, it also causes a change in its "current sheet", the stretching surface which travels billions of miles outward from its equator. During the pole reversal, this sheet becomes very wavy, and thus provides a better protection against cosmic rays.
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