A team of astronomers from the Indian Institute of Astrophysics (IIA) have made a major breakthrough in understanding how dangerous solar storms begin, capturing the closest-ever observations of shock waves triggered by a coronal mass ejection (CME) near the Sun.
The discovery was made using the Gauribidanur radio telescope, operated by the Indian Institute of Astrophysics (IIA), along with the Visible Emission Line Coronagraph (VELC) onboard India’s solar mission, Aditya-L1.
Just as a supersonic aircraft creates a sonic boom when it breaks the sound barrier, fast-moving CMEs from the Sun generate shock waves in space. These shocks can compress Earth’s magnetosphere, leading to geomagnetic storms that disrupt satellites, GPS systems, radio communications, and even power grids.
They can also intensify auroras and increase radiation risks for astronauts and high-altitude flights.
On May 27, 2024, scientists observed a CME-driven shock forming at a distance of approximately 130,000 kilometers above the Sun’s surface. The shock was traveling at nearly 1,700 kilometers per second.
According to Prof. R Ramesh, Senior Professor at IIA and Principal Investigator of VELC, this is the closest distance from the Sun at which such a shock and its associated radio burst have been unambiguously detected.
For nearly a century, scientists have debated where exactly these shock waves originate. While similar interplanetary shocks have been observed near Earth, identifying their “birth stage” near the Sun has remained challenging.
The breakthrough was possible because of the combined capabilities of the Gauribidanur radio telescope, currently India’s only dedicated low-frequency solar radio observatory, and VELC, which observes the Sun’s outer atmosphere in visible wavelengths.
Radio telescopes detect intense bursts of low-frequency emissions produced by these shocks, while VELC helps identify the exact CME responsible.
Interestingly, the sunspot group linked to the May 27 event may have been the same region that produced the powerful “Mother’s Day” solar storm earlier in May 2024. Due to the Sun’s rotation, the active region reappeared on the eastern edge of the Sun later that month.
Lead author Dr. C. Kathiravan noted that continued coordinated observations during the peak of Solar Cycle 25 could help detect CME-driven shocks even closer to the Sun, possibly within 30,000 kilometers.
The findings, soon to be published in the Journal of Astrophysics and Astronomy, mark a significant step toward improving space weather forecasting and protecting modern technological infrastructure from solar threats.
