India’s Aditya-L1 mission reveals clues to the Sun’s hot corona

Published: 14 August 2026 | The English Chronicle Desk | The English Chronicle Online

India’s first dedicated solar observatory, Aditya-L1, has produced new findings that could help scientists understand one of the Sun’s most enduring mysteries: why its outer atmosphere is dramatically hotter than the surface beneath it.

Researchers studying observations from the mission say they have found strong evidence that the Sun’s tangled magnetic fields play the dominant role in supplying energy to its corona. Their analysis suggests that magnetic-field reconnection may provide about 93% of the energy needed to sustain the corona’s extreme temperatures, while waves generated by turbulent motions on the Sun’s surface account for roughly 7%.

The findings, led by solar astrophysicist Professor R Ramesh of the Indian Institute of Astrophysics, have been published in the Astrophysical Journal Letters. Scientists say the research offers an important new benchmark for understanding how energy moves through the Sun’s atmosphere and how the star continues to replenish energy after powerful eruptions.

The corona has long presented a fundamental challenge to conventional understanding of solar physics. The visible surface of the Sun, known as the photosphere, has a temperature of around 5,500C. Yet the corona, which lies much farther from the Sun’s core, can reach temperatures of around two million degrees Celsius and, during particularly energetic events, become even hotter.

That apparently counterintuitive temperature difference is known as the coronal heating problem.

The Sun’s interior is extremely hot, with temperatures in its core reaching about 15 million degrees Celsius. Energy produced in the core travels outward through the star before eventually reaching the surface. But scientists have struggled to explain why the atmosphere above the relatively cooler photosphere becomes millions of degrees hotter.

The mystery becomes even more complicated during solar eruptions. The corona is the birthplace of some of the Sun’s most powerful space-weather events, including solar flares and coronal mass ejections, or CMEs. These events can release enormous amounts of energy and send magnetised plasma travelling through the Solar System.

CMEs can produce spectacular auroras when their particles interact with Earth’s magnetic field. But powerful events can also disrupt satellites, radio communications and navigation systems, while severe geomagnetic storms can place pressure on electricity networks.

During periods of relatively low solar activity, the Sun can produce several CMEs each day. Activity increases dramatically during the approximately 11-year solar cycle, when the number of eruptions can rise substantially.

For scientists, this raises an obvious question. If the corona repeatedly releases enormous amounts of energy through these eruptions, what mechanism replaces that energy quickly enough to keep the corona at millions of degrees?

The new Indian research points strongly towards the Sun’s magnetic field.

Scientists have long considered two major mechanisms capable of transferring energy into the corona. The first involves waves generated by the turbulent, convective movements taking place on the Sun’s surface.

The Sun is not a solid, quiet sphere. Its surface is constantly in motion, with hot plasma rising and cooler material sinking. These movements can generate waves that travel upwards through the solar atmosphere and transport energy towards the corona.

The second mechanism involves the Sun’s complex magnetic-field structure.

Magnetic-field lines extending through the solar atmosphere can become twisted, stretched and tangled as the Sun rotates and its plasma moves. Eventually, these magnetic structures can become unstable. When magnetic lines break and reconnect into a different configuration, large amounts of stored magnetic energy can be released.

Such magnetic restructuring is closely associated with solar eruptions, including CMEs.

Professor Ramesh and his colleagues used observations from Aditya-L1 to examine what happens to the corona following a particularly energetic CME recorded on 5 August 2024.

A key instrument in the analysis was the mission’s Visible Emission Line Coronagraph, known as Velc. A coronagraph is designed to observe the Sun’s outer atmosphere by blocking out the overwhelming brightness of the solar disc, allowing scientists to study the much fainter corona.

The researchers examined how the Sun’s magnetic structures behaved following the eruption. Their observations showed that within around 10 hours, the tangled magnetic-field structures had reconnected and returned towards their earlier configuration.

According to the researchers, that rapid reconfiguration provided a crucial clue.

Their calculations indicate that waves generated by turbulent surface motions do contribute energy to the corona, but their contribution is relatively small. The researchers estimate that these waves provide around 7% of the energy requirement.

The remaining 93%, they argue, comes from the continual reconfiguration of the Sun’s magnetic field.

In other words, the corona may be able to remain extremely hot because the Sun has an ongoing mechanism for restoring the energy lost during violent eruptions.

The findings do not mean that surface-generated waves are irrelevant. Solar waves remain an important component of the complex system that transfers energy from the Sun’s interior towards its atmosphere.

Instead, the study suggests that magnetic reconnection is considerably more important than previously indicated in maintaining the corona’s extraordinary temperature.

The research also highlights the importance of studying the Sun during periods of intense activity. Solar eruptions are not simply spectacular astronomical events. They are part of a much larger physical system that controls the transfer and release of energy through the solar atmosphere.

Understanding that system is increasingly important as modern society becomes more dependent on satellites, telecommunications, navigation systems and electricity networks that can be affected by space weather.

India’s Aditya-L1 mission is particularly significant because it provides scientists with a dedicated platform for continuous solar observations. Positioned around the Sun-Earth L1 point, the spacecraft is able to observe the Sun while maintaining a relatively uninterrupted view of solar activity.

The mission is expected to provide data that can be used to study solar atmospheric heating, solar wind, magnetic storms and the processes responsible for eruptions.

The latest research demonstrates how observations from the mission can be combined with detailed theoretical analysis to address fundamental questions that have remained unresolved for decades.

For Professor Ramesh and his colleagues, the results provide more than an explanation for an unusual temperature pattern. They offer evidence that the Sun’s magnetic environment is continuously reorganising itself and replenishing energy in the corona.

The finding could influence future research into how magnetic energy is stored, released and restored throughout the solar atmosphere.

Scientists caution that a single event cannot provide the complete answer to every aspect of coronal heating. The Sun is an extraordinarily complex system, and its magnetic fields, plasma, waves and eruptions interact across different scales.

More observations will therefore be needed to determine whether the same energy balance applies across different types of solar eruptions and throughout different stages of the solar cycle.

Nevertheless, the Aditya-L1 observations provide an important piece of evidence in a longstanding scientific puzzle.

The Sun may appear relatively stable from Earth, but its outer atmosphere is a highly dynamic environment in which magnetic fields are constantly being twisted, broken and reconnected. That activity may be the key to explaining why the corona remains millions of degrees hotter than the surface beneath it.

As Aditya-L1 continues its observations, researchers hope the mission will reveal more about the physical processes that govern our nearest star.

The answers could deepen understanding not only of the Sun itself but also of the fundamental physics governing stars and their atmospheres. At the same time, a clearer understanding of solar eruptions could improve humanity’s ability to anticipate and prepare for potentially disruptive space-weather events.

For now, the Indian mission has provided researchers with a compelling clue: the Sun’s tangled magnetic fields may be doing far more than simply shaping its spectacular eruptions. They could also be the mechanism that keeps its mysteriously hot corona alive.

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