In a groundbreaking discovery that may significantly alter our understanding of solar dynamics and space weather, an international team of solar physicists, led by the Indian Institute of Astrophysics (IIA), has mapped giant tides of plasma flowing beneath the surface of the sun. These hidden plasma currents, located in a zone known as the near-surface shear layer (NSSL), have been shown to shift with the sun’s magnetic activity and could be a critical piece in solving the complex puzzle of space weather phenomena that affect life on Earth.
The research, published in the prestigious Astrophysical Journal Letters, was carried out in collaboration with experts from Stanford University and the U.S. National Solar Observatory (NSO). The findings not only uncover previously invisible solar plasma flows, but also link them with magnetic field changes and solar cycles, offering new insight into the sun’s mysterious behavior.
The Hidden Engine Beneath the Sun: What is the Near-Surface Shear Layer (NSSL)?
The near-surface shear layer (NSSL) is a region that extends roughly 35,000 kilometers below the sun’s photosphere. This layer is a hotbed of turbulent plasma activity — a zone where the rotational behavior of solar material undergoes drastic changes depending on depth and latitude.
According to the Department of Science and Technology (DST), India, the NSSL is “a critical region beneath the sun’s surface,” and it’s directly influenced by the dynamic interplay of magnetic fields, solar cycles, and Coriolis forces. Understanding the NSSL is key to decoding how solar interiors are tied to external magnetic behavior — and ultimately, solar eruptions like solar flares and coronal mass ejections (CMEs) that cause geomagnetic storms on Earth.
Plasma Currents and the Sun’s Magnetic Pulse: How the Sun Breathes
The research team used helioseismology — a method similar to how seismologists study earthquakes — to trace the motions of solar material beneath the surface. Much like how seismologists use shockwaves to study Earth's inner layers, solar physicists use sound waves trapped inside the sun to measure internal movements.
Led by Professor S.P. Rajaguru and PhD student Anisha Sen at IIA, the team observed that surface plasma flows tend to converge toward latitudes where sunspots are most active. But intriguingly, these flows reverse direction midway through the NSSL, forming massive circulation cells. These cells channel plasma outward from the inner layers — a process strongly governed by Coriolis forces, the same mechanism that causes Earth’s hurricanes to spin.
“These flows are strongly influenced by the sun’s rotation and the Coriolis force,” explained the DST. “The localised flow patterns we observed matched the global trends — confirming both surface inflows and deeper outflows.”
Why This Matters: Impact on Space Weather and Earth
So why should we care about these plasma flows deep inside the sun?
The answer lies in space weather — the term for all electromagnetic and particle activity that radiates from the sun and interacts with Earth’s magnetic field. Events like solar flares, geomagnetic storms, and auroras are all driven by magnetic disturbances originating from deep within the sun.
When magnetic reconnections or sudden realignments of magnetic fields occur, they can eject massive amounts of charged particles toward Earth. These can disrupt GPS satellites, damage power grids, and pose serious risks to astronauts. Understanding the origin and behavior of such disturbances begins with a solid grasp of how internal solar flows influence external solar magnetic fields.
This new research suggests that much of what shapes these magnetic anomalies may originate in the NSSL. By studying the plasma tides in this zone, scientists can potentially improve space weather forecasting and reduce the risk posed by sudden solar storms.
Sunspots, Solar Cycles, and Magnetic Activity: The Missing Links
Sunspots — the dark patches on the sun’s surface — are visible indicators of underlying magnetic activity. They follow an 11-year solar cycle, during which the sun’s magnetic field reverses and solar activity waxes and wanes. The number and location of sunspots change over time and are used to predict the frequency of solar flares and CMEs.
The plasma tides discovered in the NSSL appear to be intricately linked to these sunspot zones. The study revealed that inflows toward sunspot latitudes occur near the surface, while outflows at deeper layers form circulation systems that are synchronized with the solar magnetic cycle.
This interplay suggests that something deeper than previously understood — possibly in the NSSL or even deeper — is controlling the rhythm of solar magnetism.
The Role of Indian Science in Global Solar Physics
This discovery is not just a milestone in astrophysics — it’s a major step forward for Indian science on the global stage. The IIA-led effort puts India at the forefront of heliophysics — the study of the sun and its influence on the solar system — and demonstrates the country’s capacity for cutting-edge space science collaboration.
IIA’s contributions to solar observations, data processing, and theoretical modeling have laid the groundwork for even more ambitious solar missions, including India’s Aditya-L1, the country's first solar observatory launched to study the sun from the Lagrange L1 point.
Coriolis Force: The Cosmic Twist Behind Solar Circulation
One of the key forces shaping the plasma flows in the NSSL is the Coriolis force. On Earth, this force is responsible for the rotation of hurricanes and ocean currents. In the sun, which rotates on its axis approximately every 27 days, the Coriolis force acts on moving plasma, creating rotational flow patterns that span thousands of kilometers.
This rotating motion twists the solar plasma and magnetic fields into loops and spirals, contributing to the complexity of solar magnetic structures. These twisted structures can store vast amounts of energy, which, when released, drive solar storms and geomagnetic disturbances.
Understanding how the Coriolis force interacts with plasma currents deep beneath the sun’s surface is a crucial part of the broader effort to model solar magnetohydrodynamics — the behavior of electrically charged fluids in magnetic fields.
What Lies Beneath: A Deeper Mystery Awaits
Perhaps the most intriguing part of this study is what it hints at but does not fully explain — that something even deeper within the sun may be orchestrating the massive flows and magnetic cycles we observe at the surface.
As Ms. Anisha Sen, the lead author, put it, “The findings hint that something mysterious is lurking in deeper layers of the sun that truly drives its global dynamics.”
Could it be that the sun has an as-yet-undiscovered internal structure influencing its entire magnetic cycle? Is there a hidden solar dynamo deeper than the NSSL?
These are the questions that will likely drive solar physics research in the coming decades.
Looking Ahead: Toward a New Era in Space Weather Prediction
This breakthrough opens the door to a more comprehensive understanding of how internal solar flows relate to external solar activity. The more we understand about the sun’s internal behavior, the better we can forecast solar storms and protect Earth-based infrastructure.
With climate change and our increasing reliance on satellite technology, building resilient systems against space weather disruptions is more important than ever. This study is a major step toward that goal.
Key Takeaways
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Plasma flows in the NSSL show inward movement at the surface and outward movement at deeper layers, forming massive circulation patterns.
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These flows shift with the sun’s magnetic pulse, linking internal solar dynamics to surface magnetic activity.
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The patterns are influenced by the Coriolis force, the same mechanism that spins hurricanes on Earth.
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The study enhances our understanding of sunspot formation, solar cycles, and space weather forecasting.
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Led by Indian scientists, this international collaboration puts India at the forefront of heliophysics research.
Conclusion
The sun, our life-giving star, remains a source of both wonder and danger. As we peel back the layers of its fiery depths, we uncover not only beautiful cosmic rhythms but also clues to phenomena that affect everything from satellite navigation to national power grids.
Thanks to the pioneering work of the Indian Institute of Astrophysics and its global partners, we are now one step closer to decoding the hidden language of the sun — a language written in plasma, magnetism, and the elegant physics of rotation.
