Scientists Traced the Sun’s Storm Engine to a Deep Hidden Layer
The Sun’s tantrums don’t begin where you think. The place where a new study of sunspot activity was observed gives us a vital hint at where solar magnetic activity originates. According to a study, solar magnetic activity originates at a thin boundary deep inside the Sun, called the tachocline. This thin boundary is located at a depth of 200,000 kilometers below the surface of the Sun, where the outer layer of the Sun’s convective zone meets its radiative zone. Scientists have long believed that this was where the Sun’s magnetic activity was caused. Now, there is direct evidence to back up this belief.
The Sun’s magnetic activity is an important phenomenon. Every 11 years, the Sun goes through a cycle of magnetic activity. During this period, more sunspots are observed on the Sun. During this period, more flares are observed on the Sun, which increases the chance of disrupting satellite communications. Once they know where the Sun’s magnetic activity originates, they can develop a more accurate way to predict the Sun’s magnetic activity.
Krishnendu Mandal and Alexander Kosovichev are scientists. They used a technique called helioseismology. This technique involves making a bell ring and listening to its sound. When waves are sent through the Sun, they can determine the movement of the Sun’s plasma by listening to these waves. By studying three decades of data collected by NASA’s SOHO satellite and a network of ground-based telescopes called GONG, they were able to study the movement of a pattern of rotating rings of plasma, or gas, like a butterfly, moving below the Sun’s surface. This phenomenon looks similar to sunspot activity.
This butterfly pattern is an important clue. Sunspots are not random features on the Sun’s disk. They are evidence of magnetic fields that arise upward from below. This new analysis shows that this underlying structure begins in the tachocline, where the sudden change in rotation rate causes shearing that could enhance the magnetic fields. NASA’s overview of the solar dynamo model has always emphasized that differential rotation and magnetic fields are crucial. But this new analysis shows where this “engine room” is.
There is a second reason that this new analysis is capturing the spotlight. This new analysis is occurring at a time when solar theorists are demystifying the tachocline in a second way. In 2025, a team of solar physicists at UC Santa Cruz announced that they had developed computer simulations of the tachocline that were self-consistent. This meant that they could produce this extremely thin boundary without imposing it artificially. This earlier analysis demonstrated that this boundary is a two-way street. That is, the tachocline is crucial in maintaining the solar dynamo. But the magnetic fields of the solar dynamo could also be maintaining the thinness of this boundary. Now observations and computation are coming together to arrive at the same conclusion that this boundary is not trivial. It is vital.
The reward for making a forecast is limited, but it is becoming more tangible. Another study, carried out in 2026, used 30 years of observed surface magnetograms as input to a 3D dynamo model and was able to make a predictive forecast several years in advance. Such breakthroughs are only possible by understanding where the relevant magnetic architecture is being constructed. Mandal wrote, The current results don’t yet provide the precise prediction of cycles, but what we’ve shown is that models which have emphasized the role of near-surface processes are missing the key layer further down. The Sun is the only star that can be studied at such a level of detail, and so any advance in solar physics is greater than any star story.
