India’s Aditya-L1 mission, the nation’s first dedicated solar observatory, has delivered breakthrough data on the Sun’s violent activity. Scientists from the Indian Institute of Astrophysics (IIA) in Bangalore, in collaboration with NASA, have made the first-ever spectroscopic observations of a coronal mass ejection (CME) in the visible wavelength range, using the Visible Emission Line Coronagraph (VELC) aboard Aditya-L1.

Launched in 2023 aboard a PSLV-C57 rocket from Sriharikota, Aditya-L1 is positioned at the Sun–Earth Lagrangian Point L1, about 1.5 million kilometres from Earth. This vantage point enables continuous, uninterrupted observation of the Sun — a critical advantage for studying solar phenomena that affect space weather and Earth's magnetosphere.

The VELC payload, developed by IIA, has been at the forefront of this effort. For the first time, scientists have observed a CME extremely close to the Sun’s visible surface, offering a new window into the processes driving these massive expulsions of solar plasma and magnetic fields.

The research team led by Dr. V. Muthupriyal, the VELC Project Scientist, and her colleagues at the IIA payload operations centre, used VELC data to measure key properties of a CME. The parameters included electron density, energy, mass, temperature, and velocity — all taken at a proximity to the Sun that has never before been achieved in visible-light spectroscopic studies.

According to their findings, the CME contained approximately 370 million electrons per cubic centimetre, compared to only 10 to 100 million electrons per cubic centimetre in the surrounding non-CME corona. The CME’s energy output was calculated at 9.4 × 10²¹ joules, dramatically exceeding the explosive power of nuclear detonations used during World War II.

The team further estimated that the mass of the CME was around 270 million tonnes, nearly 180 times greater than the iceberg that sank the Titanic. The CME’s initial velocity was recorded at 264 kilometres per second, and its temperature reached 1.8 million Kelvin, indicating the immense thermal and kinetic energy driving the solar outburst.

Prof. R. Ramesh, Senior Professor at IIA and principal investigator of the VELC project, emphasised that these are the closest spectroscopic measurements of a CME near the Sun obtained using a space-based coronagraph operating in visible light. He noted that while other telescopes can observe CMEs at greater distances, VELC’s near-Sun capability provides a direct understanding of how much mass and energy the Sun loses during such events.

The new data addresses critical questions about solar dynamics, plasma acceleration, and the early-stage evolution of CMEs — phenomena that can affect not only the Sun’s atmosphere but also the near-Earth space environment. By determining these parameters near the Sun’s surface, scientists can refine models predicting how CMEs propagate through interplanetary space and influence geomagnetic storms on Earth.

With the Sun approaching the peak of its current Solar Cycle 25, more frequent and energetic solar eruptions are expected in the coming months. The VELC, now fully operational and stable, is poised to record many such events, greatly enhancing understanding of solar activity and its implications for space weather forecasting.

Aditya-L1’s steady observations at the L1 point will allow continuous monitoring of these eruptions, enabling both Indian and international researchers to study the Sun’s dynamic corona with unprecedented detail. The mission marks a significant leap for India’s space science capabilities and strengthens global collaboration in the study of our nearest star.

Agencies