Discovery could help accurately forecast intensity of solar flares
An illustration laying a depiction of the sun's magnetic fields. Photo: NASA This story has been updated.
Till now, scientists have believed the Sun’s powerful magnetic field, responsible for solar storms that impact Earth, originated deep within the star. However, a new paper by researchers at Massachusetts Institute of Technology and University of Edinburgh has thrown a wrench into the theory. The Sun’s dynamo, the process generating the magnetic field, might be located much closer to the surface, in the star’s outermost layers, it has suggested.
These findings published in journal Nature could help in predicting solar cycles more accurately. “Our results are contributing to understanding the solar cycle better. We want to forecast if the next solar cycle will be particularly strong, or maybe weaker than normal,” Daniel Lecoanet, assistant professor at Northwestern University, told Down To Earth (DTE).
Read more: Understanding solar flares: How explosions on Sun’s surface can lead to radio blackouts
Every 11 years, the sun’s magnetic field undergoes a cycle, known as the solar cycle. The cycle is based on the sunspots, regions where the magnetic field is much higher than anywhere else on the Sun.
Sunspots are few at the beginning of a solar cycle (solar minimum) and reach their highest in the middle of the cycle (solar maximum) before decreasing again.
Lecoanet explained that previous models (which assumed the solar magnetic field is generated deep within the Sun) were unable to accurately predict whether the next solar cycle would be strong or weak.
They hope to predict the solar cycle in the same way that hurricanes are forecast. “We want to see whether a solar cycle would be strong or weak. This work is not trying to make predictions about individual solar storms,” he adds.
The team used numerical simulations to model the sun’s magnetic fields. The study’s model takes into account torsional oscillations, which are cyclical patterns in how gas and plasma flow within and around the sun.
This, according to the study, is consistent with the solar cycle. The team believes that the torsional oscillations and magnetic cycle are driven by the same physical process.
The results showed that the magnetic field is generated about 20,000 miles below the Sun’s surface, contradicting earlier studies that suggested that it was originating from about 130,000 miles below the sun’s surface.
Read more: Does space weather cause flight delays? New study spots links
“Our work provides strong evidence that the solar cycle starts near the surface of the Sun in the equatorial region,” the expert noted. Going forward, the team hopes to understand how the cycle closes.
However, not everyone is convinced by the study’s findings.
“This is a new and exciting idea, but not a serious contender to the traditional theory yet. The kind of rigorous observational tests that one would expect from a new theory trying to unseat a rather well-tested theory is missing,” Dibyendu Nandi, professor, department of physical sciences, Indian Institute of Science Education & Research, told DTE. He was not involved in the new study.
For example, Nandi explained that two of the most important aspects of the sunspot cycle are missing in the model. First is the sunspot time series, which is the up and down motion of the sunspots.
Second, he added, is the sunspot distribution butterfly diagram, which describes patterns formed by sunspots on the sun’s surface. They [the sunspots] move from mid-latitudes at the beginning of the cycle and move over time towards the equator and then at the end, they disappear.
This study comes as the Sun approaches its solar maximum. The first full week of May saw many large solar flares (when built-up magnetic energy is suddenly released) and coronal mass ejections (large expulsions of plasma and magnetic field from the Sun’s corona) sent clouds of charged particles and magnetic fields toward Earth.
The strongest solar storm to reach Earth in two decades occurred on May 14, 2024.
Read more: NASA’s NuSTAR clicks first solar image
The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center forecast solar storms and sent warnings to operators of power grids and commercial satellites to help them mitigate potential impacts. The European Space Agency (ESA) said it was still investigating the impact of this storm on their technology.
Solar storms can cause blackouts, disable satellites, and damage cell phones and Global Positioning System or GPS networks. In the most extreme cases, it can affect the power grid.
Currently, scientists can forecast the probability of an eruption on the sun’s surface, but not the exact moment of the event, according to the ESA.
“A good dynamo model will help predict a solar cycle and not space weather, which determines whether the number of sunspots can create a solar storm or CME in the next couple of days. Think of dynamo prediction as climate and space weather is more like weather,” Nandi explained.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
.png)
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.