A significant event is brewing on the Sun: a reversal of its magnetic field is imminent. This phenomenon is as intriguing as it is fascinating, marking a crucial phase in the solar cycle. But what are its real implications?
The Sun's magnetic field is about to flip.
Credit: NSF/AURA/NSO.
Every eleven years or so, the Sun undergoes a phase where its magnetic field reverses, signalling the peak of solar activity, known as the solar maximum, before descending toward the solar minimum. The last reversal occurred at the end of 2013.
The eleven-year solar cycle is marked by the appearance of sunspots, these magnetically complex regions on the Sun's surface that can trigger solar flares and coronal mass ejections (CMEs). These events are particularly frequent at the time of solar maximum, which is expected for the current cycle between late 2024 and early 2026.
A longer cycle, known as the Hale cycle, lasts about 22 years, encompassing two eleven-year solar cycles, during which the Sun's magnetic field reverses and then returns to its original state. This complex cycle significantly influences solar activity and its manifestations.
The process of magnetic reversal is primarily driven by sunspots. When they emerge near the equator, their magnetic orientation matches the old field, while those appearing near the poles align with the incoming magnetic field. This gradual shift in magnetic fields leads to a complete reversal.
During the solar maximum, a large number of sunspots are visible at mid-latitudes, and during the solar minimum, very few (sometimes none) sunspots are visible at the equator.
Credit: Future
Although the magnetic reversal is not instantaneous and can take several years, it does not have dramatic direct consequences for Earth. However, it does influence space weather and can even provide better protection against galactic cosmic rays.
By monitoring this reversal, scientists hope to better predict the intensity of future solar cycles. A rapid return to a dipolar configuration could indicate intense solar activity, while a slower process might signal a period of low solar activity.