Solar Firestorm of 2024: Indian Scientists Unravel Secrets of Rare CME Chain

In a breakthrough study that may redefine how we understand the Sun's behavior and its impact on Earth, astronomers have unveiled a rare and complex chain of solar eruptions that triggered one of the most intense geomagnetic storms in two decades. The storm, which began on 10th May 2024, lit up the skies of Ladakh with spectacular auroral displays—phenomena almost never seen at such low latitudes in India—thanks to a rare sequence of six Coronal Mass Ejections (CMEs) that erupted successively from a highly active region on the Sun.

The revelations come from a team of solar astrophysicists at the Indian Institute of Astrophysics (IIA), led by Dr. Wageesh Mishra, who used multi-point space observations and an innovative thermodynamic model to decode how these massive blasts of solar plasma interacted with each other over millions of kilometers before striking Earth.

CMEs and the May 2024 Solar Storm: A Rare Chain Reaction

CMEs are enormous bubbles of magnetized plasma hurled into space from the Sun’s outer atmosphere, or corona. When these plasma clouds head toward Earth, they can spark geomagnetic storms, disturbing satellites, GPS networks, radio communication, and power grids.

In May 2024, the Sun fired six CMEs in quick succession, all tied to a particularly volatile solar active region exhibiting both solar flares and filament eruptions. This rare combination created what scientists describe as an "interacting CME sequence"—a phenomenon seldom observed and even more rarely understood.

“This was not just a solar storm. It was a symphony of solar chaos, with six plasma waves catching up to one another, morphing, heating, and evolving as they moved through the heliosphere,” explained Dr. Mishra.

Tracing Thermal Footprints from Sun to Earth

The IIA team took on the challenge of studying not only the trajectory of these solar clouds but also their thermal states—how they heat up or cool down—as they moved from the Sun to Earth, a journey of roughly 150 million kilometers.

Until now, this aspect of CME science remained elusive due to sparse data from both near the Sun and near-Earth space. However, leveraging a novel model called FRIS (Flux Rope Internal State) and integrating it with observations from NASA’s Wind spacecraft, ESA's SOHO, and India’s Indian Astronomical Observatory in Hanle, the scientists succeeded in tracking the full thermodynamic evolution of these CMEs.

From Heating to Heat-Absorbing Clouds

The team discovered something unexpected. Initially, the CMEs behaved as expected—releasing heat. But midway through their journey, they entered a polytropic transition, shifting into a regime where they began to absorb and retain heat, stabilizing at near-constant temperatures.

By the time the solar clouds reached Earth, the researchers noticed two particularly strange magnetic structures—“double flux ropes”—within the final CME. These twisted bundles of magnetic fields were intertwined like braids, producing abnormal patterns of heating and cooling.

Lead author and doctoral scholar Soumyaranjan Khuntia explained, “These flux ropes were not just magnetic anomalies. They showed differentiated heating between electrons and ions, with electrons cooling while ions retained heat—something never seen before in such coordinated complexity.”

Unprecedented Modeling of Polytropic Indices

Using the FRIS model, the team calculated polytropic indices, which describe how pressure and temperature relate as a gas expands or compresses. These indices were measured both near the Sun and at 1 AU (the average Earth–Sun distance). They revealed that each CME segment evolved differently, with interactions between the six CMEs causing significant shifts in thermal behavior.

“The fact that we could map these changes from near the Sun all the way to Earth is a first in India—and likely a global first,” said Dr. Mishra. “This kind of study is crucial for developing next-generation space weather forecasting tools.”

Toward Predicting Solar Tempests

The research not only captured a landmark moment in heliophysics but also offers a new dimension to space weather prediction. Co-author Anjali Agarwal, also a doctoral scholar at IIA, said: “We’re exploring whether thermal profiles—how hot or cold different parts of a CME get—can help us predict the severity of future geomagnetic storms. If successful, this would revolutionize forecasting accuracy.”

These insights have been published in the prestigious Astronomy and Astrophysics Journal, marking a milestone for Indian-led solar research at the global level.

The Role of Aditya-L1: India’s Future in Solar Forecasting

Looking ahead, the IIA team is excited about integrating data from Aditya-L1, India’s first dedicated solar observatory, launched by ISRO. Instruments such as the Visible Emission Line Coronagraph (VELC) and Aditya Solar Wind Particle Experiment (ASPEX) will provide uninterrupted, close-up views of the Sun and near-Earth space.

“These instruments will enable a full Sun-to-Earth tracking of CMEs—capturing how they originate, how they evolve, and how they strike,” said Dr. Mishra. “This will significantly improve our predictive capabilities, and possibly warn us of geomagnetic storms days in advance.”

A Celestial Spectacle Over Ladakh

While the scientific findings are profound, the visible result of this storm also stirred awe. For a brief period in May 2024, the skies above Hanle, Ladakh, glowed with ribbons of red and green—aurora borealis—a spectacle rarely seen in India due to its low geomagnetic latitude.

The Hanle observatory, already known for its pristine viewing conditions, became a stage for one of nature’s most dramatic space-weather shows, witnessed by researchers and local residents alike.

This study not only chronicles a once-in-a-generation solar event but also lays the groundwork for forecasting future threats from space. As solar activity continues to ramp up toward Solar Maximum in 2025, understanding these cosmic tempests has never been more critical.