# Aditya-L1's VELC produces Doppler images that show which way solar eruptions travel

URL: https://upsc.help/current-affairs/2026-10-21/aditya-l1-velc-doppler-images/
Date: 21 October 2026 (2026-10-21)
Source: The Hindu, Page 12
UPSC papers: GS3
Publisher: upsc.help (Pratidin), free and open-source UPSC Civil Services current affairs. Not affiliated with UPSC. Every fact was checked against the source reports by a separate review before publishing.

**In one line:** Software developed at the Indian Institute of Astrophysics turns data from Aditya-L1's VELC into Doppler velocity images of the solar corona, showing whether solar plasma, including CMEs, is moving towards or away from Earth.

India's solar mission Aditya-L1 has produced Doppler velocity images of the Sun's corona, the hot outer atmosphere, using its Visible Emission Line Coronagraph (VELC), The Hindu reported. The images show whether coronal plasma is moving towards or away from the observer, and so reveal the direction in which coronal mass ejections (CMEs) travel along the Sun-Earth line. Dr. V. Muthupriyal and her team at the Indian Institute of Astrophysics (IIA), Bengaluru, developed the software that processes VELC's data into these images. The technical details have been published in the Astrophysical Journal after peer review, and the processed images will be shared with the global scientific community.

The images rest on the Doppler effect: light from plasma moving towards an observer shifts to shorter wavelengths, and light from plasma moving away shifts to longer ones. VELC, one of Aditya-L1's seven payloads, is a coronagraph that blocks the Sun's bright disc and also splits the corona's light into a spectrum. It records three emission lines of highly charged iron, at 5303 Å, 7892 Å and 10747 Å. The report said VELC is "currently unique in its capability to generate such spectroscopic images in the visible wavelength range." CMEs are massive clouds of plasma that can disrupt satellites and communication systems, so their direction matters for space weather forecasting.

Aditya-L1, India's first space-based solar mission, was launched on 2 September 2023 and placed in a halo orbit around the Sun-Earth Lagrange point L1, about 1.5 million km from Earth, on 6 January 2024. In December 2024 ISRO reported a VELC result: observations of a CME on 16 July 2024, in which plasma was found moving away from the observer at about 10 km/s. The instrument team has also noted limits: the 5303 Å channel gives usable data, while the other two spectral channels are currently too noisy for science use.

## Prelims facts

- Aditya-L1's VELC has produced Doppler velocity images of the solar corona that show whether plasma is moving towards or away from Earth.
- The processing software was developed at the Indian Institute of Astrophysics, Bengaluru, which also built VELC.
- VELC observes iron emission lines at 5303 Å, 7892 Å and 10747 Å; the 5303 Å channel currently gives the usable data.
- Aditya-L1 was launched on 2 September 2023 and has been in a halo orbit around L1, about 1.5 million km from Earth, since 6 January 2024.

## Quick recall

- **What does VELC stand for?** Visible Emission Line Coronagraph
- **Which institution built VELC and its Doppler software?** The Indian Institute of Astrophysics, Bengaluru
- **When was Aditya-L1 launched?** 2 September 2023
- **When did Aditya-L1 reach its halo orbit around L1?** 6 January 2024
- **How far is L1 from Earth?** About 1.5 million km
- **How many payloads does Aditya-L1 carry?** Seven
- **Which VELC emission line currently gives usable science data?** 5303 Å, from highly charged iron (Fe XIV)
- **What does a positive Doppler velocity mean in VELC images?** Plasma moving away from the observer

## Prelims practice question

With reference to the Aditya-L1 mission, consider the following statements:
1. It is placed in a halo orbit around the Sun-Earth Lagrange point L1.
2. Its Visible Emission Line Coronagraph was built by the Indian Institute of Astrophysics.
3. It carries a single payload.
Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answer: (a) 1 and 2 only. Statement 1 is correct: it reached a halo orbit around L1 on 6 January 2024. Statement 2 is correct: VELC was built by IIA, Bengaluru. Statement 3 is incorrect: Aditya-L1 carries seven payloads.

## UPSC previous-year questions this connects to

- UPSC Mains 2016, GS3: Discuss India's achievements in the field of Space Science and Technology. How the application of this technology has helped India in its socio-economic development? (https://upsc.help/pyq/q060-india-s-achievements-field-space-science-technology/)
  How to use this story in the answer: Cite Aditya-L1's VELC as an indigenous space science achievement with a practical use: forecasting solar storms that threaten satellites and communication.
- UPSC Mains 2017, GS3: India has achieved remarkable successes in unmanned space missions including the Chandrayaan and Mars Orbiter Mission, but has not ventured into manned space mission, both in terms of technology and logistics? Explain critically. (https://upsc.help/pyq/q058-india-has-achieved-remarkable-successes-unmanned-space/)

## Mains practice question

What are coronal mass ejections, and why does knowing their direction matter? Explain how Aditya-L1's VELC contributes to space weather forecasting. (150 words)

### Model answer

Coronal mass ejections (CMEs) are huge clouds of magnetised plasma thrown out from the Sun's corona. In October 2026, Aditya-L1's VELC produced Doppler images that show their direction of travel.

## Why direction matters

- Earth-directed CMEs can disrupt satellites, communication systems and navigation.
- In ordinary coronagraph pictures, a CME moving towards Earth and one moving away can look alike.

## VELC's contribution

- **Doppler imaging:** shifts in iron emission lines, such as 5303 Å, show plasma speed along the Sun-Earth line.
- **Indigenous capability:** VELC and its software were developed at the Indian Institute of Astrophysics; the method is published in the Astrophysical Journal.
- **Vantage point:** a halo orbit around L1, about 1.5 million km away, gives an uninterrupted view of the Sun.
- **Open data:** processed images will be shared with scientists worldwide.
- **Limits:** only the 5303 Å channel gives usable data now.

VELC adds an Indian input to global space weather forecasting.

## The basics

## Why this matters

The Sun sometimes throws out huge clouds of charged gas called coronal mass ejections (CMEs). If one heads towards Earth, it can disturb satellites, radio links and power grids. Knowing early whether a CME is coming towards us or going away is the heart of space weather forecasting. India's solar observatory, Aditya-L1, now produces images that help answer exactly that question.

## Where Aditya-L1 sits

Aditya-L1 is India's first space-based solar mission. It was launched on 2 September 2023 and placed in a halo orbit around the Sun-Earth Lagrange point L1, about 1.5 million km from Earth, on 6 January 2024. From there it watches the Sun without interruption. See Lagrange points and halo orbits.

## The instrument

The Visible Emission Line Coronagraph (VELC), built by the Indian Institute of Astrophysics (IIA), Bengaluru, is one of seven payloads. A Coronagraph blocks the Sun's bright disc so that the faint outer atmosphere, the corona, can be seen. VELC also splits the corona's light into a spectrum. It records three emission lines from highly charged iron: 5303 Å, 7892 Å and 10747 Å.

## How a Doppler image works

When a light source moves towards you, its waves are squeezed and the line shifts slightly to the blue; when it moves away, the line shifts to the red. This is the Doppler effect. By measuring the shift at every point, the IIA team's software makes a map of how fast the corona's plasma is moving along the Sun-Earth line. A CME moving towards Earth and one moving away look similar in a normal picture, but not in a Doppler image.

## Why it is a first

According to the report, VELC is "currently unique in its capability to generate such spectroscopic images in the visible wavelength range." The processing method has been published in the Astrophysical Journal, and the images will be shared with scientists worldwide.

## Sources

- https://superkalam.com/current-affairs/21-10-2026/aditya-l1-mission-offers-new-insights-into-the-direction-of-solar-eruptions-pg12-1b1eda23-8605-465b-83d1-692ee4bc79a5
- https://www.newsbytesapp.com/news/science/aditya-l1-captures-doppler-velocity-images-of-the-suns-corona/tldr
- https://plutusias.com/aditya-l1s-doppler-images-breakthrough-in-solar-coronal-studies-for-upsc/
- https://www.isro.gov.in/Aditya_L1_Observations_Coronal_Mass_Ejection.html
- https://arxiv.org/html/2503.21184