The Sun, one of the most dynamic celestial bodies in our galaxy, is deeply intertwined with solar physics and space weather phenomena. A recent discovery by a team led by astronomers from the Indian Institute of Astrophysics (IIA) has shed profound light on the subtle yet profound dynamics at the heart of the Sun—its near-surface shear layer (NSSL). This region, located just below the Sun’s surface at depths extending to about 35,000 kilometers, is a critical zone where hidden plasma flows shift with the Sun’s magnetic heartbeat and influence space weather. The study led by IIA researchers has uncovered how these intricate solar currents manifest over time, providing valuable insights into the Sun’s internal dynamics and its role in shaping global solar activity.

The near-surface shear layer (NSSL) is a unique zone beneath the Sun’s surface where distinct rotational behaviors dominate. These behaviors vary with depth and are influenced by active region magnetic fields, as well as the Sun’s 11-year sunspot cycle—a manifestation of its magnetic activity that repeats predictably on Earth. A study published in The Astrophysical Journal Letters by astronomers from IIA, along with researchers from Stanford University (USA) and the National Solar Observatory (NSO, USA), explored these dynamic processes.

Using helioseismology—a advanced technique that tracks sound waves as they travel through the Sun—the team observed changes in solar material over a decade of data collected by NASA’s Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) and the Global Oscillations Network Group (GONG). This comprehensive dataset allowed them to trace how solar material shifts with depth, revealing fascinating patterns near the Sun’s surface.

The research revealed that surface plasma flows converge toward active sunspot latitudes but reverse direction midway through the NSSL, flowing outward to form circulation cells. These local currents are strongly influenced by the Sun’s rotation and the Coriolis force—the same force responsible for shaping hurricanes on Earth. The Coriolis effect causes inflows and outflows in solar material to spiral, shaping how the Sun rotates at different depths—creating a subtle yet powerful sculptor of its internal dynamics.

By analyzing these surface flows, the researchers found that they do not power the Sun’s larger-scale zonal flows, which ripple through the Sun’s vast interior. Instead, deeper outflows and circulation cells influence the Sun’s rotation and shear gradient at different depths—thereby shaping rotational shear (δ(∂Ω/∂r)) for two layers of significant depth: 0.99 and 0.95 solar radii.

The findings further highlight the link between internal hidden patterns and global space weather effects. By observing these subtle yet profound solar currents, astronomers can better understand how the Sun’s subsurface dynamics influence solar activity and, consequently, Earth’s space weather systems, such as satellite communication networks and power grids.

Conclusion: In summary, the discovery by IIA researchers provides a deeper understanding of the Sun’s complex internal dynamics, revealing how subtle near-surface processes shape the Sun’s magnetic cycle and its role in shaping global solar activity. While significant progress has been made into unraveling the mysteries of the NSSL and its influence on space weather, there remain unanswered questions regarding deeper layers of the Sun. These discoveries underscore the Sun’s far-reaching impact on solar physics, astrophysics, and Earth’s environment, making it a frontier of scientific inquiry with profound implications for our understanding of the universe.