Something strange is happening with the Sun.
So far in 2022, it has exploded in flares and coronal mass ejections virtually every day, with some of the most violent outbursts our star has ever seen.
An exploding Sun isn't unusual in and of itself. It erupts on a regular basis, going through phases of high and low activity in 11-year cycles.
The current solar cycle's activity is much higher than official NASA and NOAA estimates, and solar activity has continuously surpassed expectations dating back to September 2020. A solar scientist, on the other hand, will tell you that this isn't all that strange.
"We can't reliably predict solar cycles," said solar astrophysicist Michael Wheatland of the University of Sydney.
"We don't completely understand the solar dynamo, which generates the magnetic fields seen at the surface as sunspots, and which produce flares. This is one of the outstanding problems in astrophysics; the inaccuracy in the prediction is unsurprising."
Sure, it's unsurprising. But what if the lack of surprise – that we expect to be lousy at predicting solar cycles – indicates we need to rethink how we do it entirely? What if we're using the wrong metric to make our predictions?
From 11 to 22 years
Solar cycles have a significant influence on the Solar System, yet they are mostly unknown. Scientists have discovered that they are closely tied to the solar magnetic field, which bends, swirls, and loops around the surface of our Sun.
The Sun's magnetic poles switch every 11 years or so, with north becoming south and vice versa. This change occurs at solar maximum, which is marked by a peak in sunspot, flare, and coronal mass ejection (CME) activity.
Following this reversal, activity decreases before increasing again to a peak. This is where we are today, in the current cycle's escalation phase, the 25th since we began counting.
The number of sunspots visible on the Sun is used to describe and predict activity cycles. These are transient areas where magnetic fields are exceptionally strong, allowing flares and CMEs to erupt. Because the magnetic field prevents the passage of hot plasma, they appear as black areas that are colder and dimmer than their surroundings.
Predicting solar cycles solely on how many sunspots we count is an issue, according to solar physicist Scott McIntosh of the US National Center for Atmospheric Research.
"The sunspot cycle is not the primary thing. It's a secondary thing," he stated. "And the way the canon is written, the way the textbooks are written, the way solar activity is presented, it's portrayed as the primary."
"The problem is that it's really not, and the underlying Hale cycle, the 22-year magnetic cycle, is the primary. And the sunspot cycle is just a tiny subset of this bigger picture."
George Ellery Hale, a US astronomer, discovered the Hale cycle in the early twentieth century. It is made up of two 11-year sunspot cycles, which is the amount of time it takes for the poles to exchange locations twice and then return to their original positions.
In contrast to 11-year cycles, Hale cycles may be seen in a variety of occurrences. These include the strength of galactic cosmic rays hitting Earth, as well as the shifting magnetic polarity of sunspots and solar magnetic poles.
Solar activity makes it more difficult for cosmic rays to reach Earth, yet cosmic radiation waveforms change between the odd- and even-numbered solar cycles. The polarity of the solar magnetic field has been blamed for this.
Explaining sunspots
It's critical to recognize that we don't have a solid understanding of what goes on within the Sun. A dynamo within the star, a revolving, convecting, and electrically conducting fluid that transforms kinetic energy into magnetic energy, spinning a magnetic field out into space surrounding the Sun, is assumed to be responsible for the solar magnetic field.
If that's the case, what creates sunspots? According to current theories, they are linked to the rotation of the Sun. The equator of the sun spins faster than the poles. If straight longitudinal magnetic field lines were dragged along with the rotation, they would stretch and eventually tangle, resulting in sunspots, which are transitory, localized zones of intense magnetic fields.
This is reliant on the magnetic field being passive, according to McIntosh.
"You have a very complex system inside the Sun. Like all physical systems, we make simplifications or approximations to try and understand what's going on," he explained.
"About 60 years ago, they made an approximation with the magnetic fields – that they were small compared to the fluids on the Sun. Therefore, when the Sun is circulating, like our planet does, the rotation drives circulation, the heating of the atmosphere drives circulation, and with all this circulation going on, the magnetic fields just get dragged around with the circulation."
The first magnetic fields occur at roughly 30 degrees latitude in the animations, which corresponds to observational data of sunspots. But, according to McIntosh and colleagues, this is because the model was designed to explain only this.
There's also this: The magnetic fields of overlapping Hale cycles produce sunspots, which are an interference pattern.
In 2011, McIntosh and colleagues discovered a trend in sunspot data: an overlap in so-called butterfly diagrams. Sunspot appearances by latitude are plotted through time in these graphs.
When the researchers realized this, they went out and collected as much historical sunspot data as they could, dating all the way back to the 1860s.
They discovered that the overlap persisted. The emergence of the next cycle's sunspots may be seen around mid-latitudes at the conclusion of one sunspot cycle, as the sunspots get closer and closer to the equator.
These are signs of oppositely polarized bands of magnetic activity moving around the Sun in cycles, according to the researchers; they would be accountable for the sunspot cycle, but not driven by it. Furthermore, the cycles can interact; when two oppositely polarized cycles overlap, they interfere with one another.
As a result, the magnetic systems mutually impede the creation of sunspots, resulting in a period of low sunspot activity.
"The sunspot cycle is a result of the interaction between these larger magnetic cycles," McIntosh noted. "In other words, it's like an interference pattern. The magnetic fields want to cancel one another all the time."
More data, always more data
McIntosh and his colleagues developed projections for the current solar cycle based on the results of the 'interference pattern,' which are more in line with current observations than official estimates based on sunspot counts.
At this point, though, it's all theoretical.
For example, we still don't know what causes the bands of magnetic activity throughout the Sun; experts believe gravity waves are to blame, but we don't have enough data to know for sure.
"Scott McIntosh's ideas are interesting, and the Mcintosh/Leamon [that's Robert Leamon of the University of Maryland's Goddard Planetary Heliophysics Institute] forecast for cycle 25 is closer than the official one at this stage. However, it is not based on a physical model. I doubt it has more predictive power than the other observationally-based approaches to prediction," Wheatland said.
We'll need additional data to learn more, which will take time to collect. It involves looking at the Sun's high latitudes, up towards the poles, while a new cycle forms, according to McIntosh.
Because of Earth's orbit around the solar equator, we seldom view the solar poles; nevertheless, the European Space Agency's Solar Orbiter will be swooping over just as a new cycle begins.
McIntosh feels there's something to the fact that his team's prognosis is more in line with the current state of solar cycle 25. The team's proposals, at the very least, warrant a second look and some serious research.
"We've been pretty much spot on for about 10 years, but it's not diffusing through the scientific community," he remarked.
"This solar cycle provided an opportunity. Because our prediction was so diametrically opposite to what the consensus panel was showing, that means that if we end up being close, then we really need to take a second look at how stars make magnetic fields."
"Maybe it's closer to the way that we're seeing that's happening, versus the old way. And it could be a hybrid, some mix of the two. It probably is."
