The Sun is Expected to Enter a ‘Battle Zone’ After the Crescendo of Solar Maximum

The Sun will soon enter a so-called ‘battle zone’ phase that is expected to follow this solar cycle’s maximum, according to newly-formed space weather prediction company Lynker Space. Although this phase stabilizes the swarm of magnetic fields across the surface of the Sun, it also increases the chance that large coronal holes might form—and the geomagnetic storm-inducing solar winds that they generate.

Although the number of sunspots that appear on the Sun’s surface have been used to define each 11-year solar cycle for centuries, researchers are beginning to realize that the magnetic fields that migrate from pole to equator may play a more important role in governing solar activity than previously assumed, with the polarity of the Sun’s overall magnetic field flipping from north to south at each solar maximum.

The period covering a magnetic polarity flip from north to south and back to north again is a 22-year period called the Hale cycle, which marks the journey of bands of magnetic fields, called Hale cycle bands, from their formation at the Sun’s poles to where they meet at the equator during the next solar cycle; when the two opposing bands meet they cancel one-another out in what is called a ‘termination event’ that marks the solar minimum.

As this journey takes two solar cycles to complete, there can be either one or two bands in each hemisphere at any given time: the dissolution of one of the bands in each hemisphere during the solar minimum’s termination event leaves only one band on either side of the equator, a situation that destabilizes the individual magnetic fields across the Sun’s surface, resulting in the formation of the sunspots that are characteristic of a solar maximum.

But the presence of a second Hale band, formed at solar max, competes with its equator-bound counterpart—essentially forming a ‘battle zone’ between the two—an effect that stabilizes the smaller fields, resulting in a steady reduction in sunspot activity until the Sun reaches that cycle’s solar minimum.

Although the reduction in sunspots also signals a corresponding decline in solar flare activity, the stabilization of the magnetic fields allows coronal holes, large gaps in the Sun’s magnetic field, to form. These holes allow the solar wind to flow freely from the Sun’s surface wherever they occur, increasing the chances of geomagnetic storm activity if these amplified streams of charged plasma happen to be pointed at Earth.

Although these coronal holes lack the high-energy X-ray emissions generated by solar flares, the geomagnetic disturbances that the intensified solar wind’s charged particles can generate can expand the planet’s atmosphere, increasing the amount of aerodynamic drag that acts on satellites in very low orbits. Although the atmosphere at those altitudes is incredibly sparse, the effect can eventually drag a spacecraft out of its orbit, making it a concern for satellite operators.

“We have never had so many objects in low-Earth orbit [around 10,000],” according to solar physicist and Vice President of Lynker Space, Scott McIntosh. Recent years have seen record numbers of satellite launches, with companies such as SpaceX putting entire constellations into space, resulting in thousands of new devices being put into orbit in a short period of time.

“We will be seeing in real time what the impact of the battle zone is on the businesses fighting to survive and succeed in that environment.”

Although this solar cycle has yet to reach its maximum, McIntosh said that once the ‘battle zone’ starts it could last until 2028, a period that could see a 50 percent increase in geomagnetic activity in the upper atmosphere. “The potential for large, dangerous geomagnetic storms in the next few years is very real,” McIntosh added.

Although the battle zone’s coronal holes are unlikely to cause any major disruptions for us on the planet’s surface, it would be unwise to let our guard down as  the most intense geomagnetic storm in recorded history, the 1859 Carrington Event, occurred during an otherwise-average solar cycle, an event that, if it were to happen today, would be devastating to our modern electrical grid. Whitley outlines the danger presented by solar storms of that magnitude—and what needs to be done to weather such a storm—in his 2012 ebook Solar Flares: What You Need to Know.