India’s first dedicated solar mission, Aditya-L1, has achieved another significant milestone by generating Doppler velocity images of activity within the Sun’s corona, the outermost layer of the solar atmosphere, The Hindu reported.

The breakthrough was made using data collected by the Visible Emission Line Coronagraph (VELC), one of the mission’s key scientific instruments.

Scientists at the Indian Institute of Astrophysics (IIA) processed and analysed the observations to produce these unique images. The development is expected to enhance scientists’ understanding of how coronal mass ejections (CMEs) travel through space, particularly along the Sun-Earth direction, an area that has remained difficult to observe directly until now.

Solar activity regularly leads to the ejection of extremely hot plasma from the Sun. Among the most dramatic manifestations of this activity are CMEs, which are massive clouds of magnetised plasma expelled from the solar atmosphere at high speeds.

These eruptions can move in any direction away from the Sun. However, when a CME is directed towards Earth, it can interact with the planet’s magnetic environment and potentially trigger space weather disturbances that affect satellites, navigation systems, communication networks and power infrastructure.

For this reason, determining the direction of a CME immediately after it erupts is considered crucial for improving space weather forecasting and assessing possible impacts on Earth.

To achieve this, researchers applied the Doppler effect to light, a principle similar to the one commonly demonstrated through sound. In everyday life, the pitch of a train’s whistle appears higher as the train approaches an observer and lower as it moves away.

Scientists explained that the same underlying principle can be applied to light waves emitted by solar plasma. By measuring subtle shifts in the wavelength of light, they can determine whether material in the solar corona is moving towards or away from the observer.

The resulting Doppler velocity images provide this information visually. Positive Doppler velocities indicate plasma moving away from the observer, while negative Doppler velocities signify plasma moving towards the observer.

This capability offers a new dimension to solar observations because conventional coronagraph images largely reveal motion across the sky, whereas Doppler measurements provide information about movement along the observer’s line of sight. Such data can be especially valuable in identifying Earth-directed solar eruptions.

The software used to process the VELC observations and generate the Doppler velocity images was developed by Dr V Muthupriyal, Senior Project Scientist with the VELC payload operations team at the Indian Institute of Astrophysics, along with her colleagues.

The technical methodology behind the data-processing framework has undergone international peer review and has been published in the Astrophysical Journal, highlighting the scientific rigour of the achievement.

According to Prof. R Ramesh, Senior Professor at the Indian Institute of Astrophysics and Principal Investigator of the VELC project, the Doppler velocity images of the solar corona are unique and represent a capability currently available only through VELC.

He noted that the instrument’s specialised spectroscopic observing system allows it to measure coronal plasma motions in visible wavelengths from the Sun-Earth L1 Lagrangian point, a location approximately 1.5 million kilometres from Earth that provides an uninterrupted view of the Sun.

VELC was specifically designed to conduct both imaging and spectroscopic observations of the solar corona. Its ability to study multiple emission lines enables researchers to investigate plasma motion, temperature and other physical properties with exceptional detail.

The achievement further strengthens Aditya-L1’s role in global heliophysics research. By helping scientists track the early evolution and direction of CMEs more accurately, the mission is expected to improve understanding of solar storms and their effects on the near-Earth environment.

The processed Doppler velocity images will be shared with the wider scientific community. These datasets will complement the mission data already available in the public domain and are expected to support future international research into solar activity, coronal dynamics and space weather prediction.

As Aditya-L1 continues operations from its halo orbit around the Sun-Earth L1 point, the mission is steadily delivering new insights into the behaviour of the Sun, reinforcing India’s growing contribution to advanced solar science and space-based observations.

Agencies