Geomagnetic storms, solar flares and the Sun’s cycle are phenomena that have become part of our normal vocabulary. These should now be add a new expression to them: the solar battle zone. Although solar maximum has just officially begun, some scientists warn that solar activity will not reach its maximum peak until this explosive phase is over and we enter the aforementioned battle zone.
This relatively little studied phase of the solar cycle, in which giant holes appear in the Sun’s corona, could end up being disastrous for the satellites orbiting the Earth, which have multiplied exponentially since the last solar cycle (more than a decade ago), experts warn. But let’s go from the beginning. Solar maximum is the period of the Sun’s approximately 11-year solar cycle, or sunspot cycle, in which the number of dark spots visible on the Sun reaches its maximum.
This period is characterized by powerful solar flares that explode from the solar surface and throw clouds of charged particles at Earth, which triggers intense geomagnetic storms and are responsible for beauty, in the form of auroras, and also for problems with communications and interference in electromagnetic currents.
Halfway through this period, the Sun’s magnetic field changes completely.leading to a final reduction in sunspots and solar activity until we reach minimum activity and the next solar cycle begins. But scientists at Lynker Space, who specialize in space weather prediction, published a report in which they explained that a new phase of the solar cycle, known as the battle zone, will likely begin in the next year or two, when solar maximum ends.
Solar physicist Scott McIntosh noted in an interview that geomagnetic activity in the upper atmosphere could increase by up to 50% during the battle zone and could last well into 2028: “The potential for large and dangerous geomagnetic storms in the coming years is very real,” said this expert.
What is the battle zone? In addition to the 11-year sunspot cycle, the Sun also has a longer 22-year Hale cycle, which is the time it takes for our star’s magnetic field to change. During this longer cycle, large bands of magnetism, known as Hale cycle bands, emerge at the Sun’s poles and slowly migrate toward the solar equator, independently of the Sun’s broader magnetic field. A new band emerges in both hemispheres of the Sun. Sun during each solar maximum and lasts until the end of the next sunspot cycle, when the bands reach the solar equator and disappear in what researchers call a “solar termination” event. This means that During the first half of a sunspot cycle (from solar minimum to solar maximum) there is only one band of the Hale cycle in each of the Sun’s hemispheres. But during the second half of a cycle (after solar maximum), there are two bands in each hemisphere.
The overlap of these giant bands is what governs the sunspot cycle, explains McIntosh. When there is only one band in each hemisphere, there is a magnetic imbalance throughout the Sun, with weaker magnetic fields near the equatorallowing the number of black spots to increase around our star’s waist, he said.
“But when a second band is established, reduces imbalance and hinders the formation of sun spots – adds McIntosh -. Finally, within a few years, as the bands move toward the equator, the imbalance progressively decreases until the Sun cannot produce any sunspots.”
The Hale cycle bands have historically been overlooked by most space meteorologists who rely more on sunspot number to predict solar activity. However, some scientists are beginning to realize that magnetic stripes are more important than we thought. For example, studying the solar terminator event that preceded the current solar cycle allowed McIntosh and others predict correctly the arrival of solar maximum when other experts did not.
The reason the battle zone is potentially more dangerous than solar maximum is twofold: First, the number of solar flares emerging from the Sun remains high for several years after solar maximum, which It means that the Earth is affected by as many solar storms as we are receiving now; Second, the magnetic tug-of-war between the Hale cycle bands triggers the formation of coronal holes: giant dark patches created by the sun’s magnetic field that pass through the solar corona, or outer atmosphere.
Coronal holes are dangerous because can create short, extreme bursts of solar wind – the constant stream of charged particles ejected by the Sun. For example, in December 2023, a coronal hole wider than 60 Earths bombarded us with solar wind; and in 2022, a coronal hole created a “hole” in the solar wind, so large that it briefly “blew” Mars’ atmosphere.
For most people on Earth, the battle zone poses very little threat. It could even be good news for aurora hunters because the chances of seeing the dancing light shows are even higher during this period.
However, This period could be very difficult for satellite operators because all this additional geomagnetic activity can cause the upper atmosphere to swell. When this happens, spacecraft in orbit can experience additional drag, causing them to fall back to Earth; this has already happened during the current solar maximum. With new satellites launching in record numbers thanks to projects like SpaceX’s Starlink constellation, the chances of solar weather causing disastrous satellite failures are increasing.
“We have never had so many objects in low Earth orbit (around 10,000) – concludes McIntosh -. We will see in real time what the impact of the battle zone is on the companies that fight to survive and succeed in that environment”.