Anantam IASCurrent Affairs · 10 November 2025

Aditya-L1’s Close Look at Coronal Mass Ejections (CMEs)

General Studies · Science & Tech

Why in News?

Scientists from the Indian Institute of Astrophysics (IIA), using the Visible Emission Line Coronagraph (VELC) payload aboard India’s Aditya-L1, collaborated with NASA to study a Coronal Mass Ejection (CME).

UPSC Relevance

Prelims, GS3, Awareness in the fields of IT, Space, Computers, Robotics, Nano-technology, Bio-technology and issues relating to Intellectual Property Rights.

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2025

Consider the following space missions:

I. Axiom-4

II. SpaDeX

III. Gaganyaan

How many of the space missions given above encourage and support micro-gravity research?

a) Only one

b) Only two

c) All the three

d) None

2024 – What are asteroids? How real is the threat of them causing extinction of life? What strategies have been developed to prevent such a catastrophe?

The Observations

These are the very first spectroscopic observations of a CME in the visible wavelength range close to its lift-off from the Sun.
Location Advantage: Aditya-L1’s positioning at the Sun-Earth Lagrangian L1 point provides a sustained, 24-hour view of the Sun, which is crucial for these observations.
Scientists used the VELC to estimate crucial parameters of the CME very close to the Sun’s visible surface.
- Electron Density: Approximately 370 million electrons per cubic centimetre (significantly higher than the non-CME corona’s 10-100 million).
- Energy: Estimated to be around 9.4 × 10²¹ joules.
- Mass: Nearly 270 million tons.
- Initial Speed: 264 km/sec.
- Temperature: 1.8 million degrees on the Kelvin scale.

Future Expectations

The unique near-Sun spectroscopic data from VELC is vital for understanding the parameters of a CME in relation to what is lost from the Sun during such an event.
With the Sun nearing its maximum activity phase of the current sunspot cycle 25, the now-stabilised VELC is expected to observe more energetic eruptions.

CME vs Solar Flare

Feature	Solar Flare	Coronal Mass Ejection (CME)
Primary Output	Electromagnetic Radiation (photons, including X-rays and Gamma-rays).	Mass/Matter (a gigantic cloud of superheated plasma, or charged particles, embedded with a magnetic field).
Analogy	Like the muzzle flash of a cannon.	Like the cannonball itself.
Speed to Earth	Speed of light (~300,000 km/s). Reaches Earth in about 8 minutes.	Much slower (from a few hundred to over 3,000 km/s). Takes 15 hours to 3 days to reach Earth.
Duration	Brief, lasting from minutes to a few hours.	Longer event, occurring over several hours as the massive cloud billows away.
Effect at Earth	Radio blackouts and degradation of navigation signals (due to radiation hitting the ionosphere).	Geomagnetic storms (due to the magnetic cloud hitting Earth’s magnetosphere), potentially causing power grid disruptions, satellite damage, and intense auroras.
Correlation	The strongest flares are often, but not always, associated with CMEs.	CMEs sometimes occur without a strong solar flare being detected (called a “stealth CME”).

About Aditya-L1 Mission

India’s First Solar Mission: It is the first dedicated space-based Indian mission to study the Sun.
The Aditya-L1 mission was launched on September 2, 2023 by ISRO using the PSLV-C57 rocket from the Satish Dhawan Space Centre (SDSC) in Sriharikota.
Strategic L1 Orbit: It is placed in a halo orbit around the Sun-Earth Lagrange Point 1 (L1), approximately 1.5 million km from Earth.
- Unique Advantage: This L1 location provides a continuous, uninterrupted view of the Sun without occultation (eclipses), enabling real-time monitoring of solar activity.
Focus on Coronal Heating: A primary objective is to address the major unsolved problem of why the Sun’s outermost layer (the Corona) is dramatically hotter (millions of degrees) than its surface (the Photosphere, around 6,000 K).
VELC Payload (The Coronagraph):
- The Visible Emission Line Coronagraph (VELC) is the main instrument.
- It is the closest-to-the-Sun space coronagraph currently capable of performing simultaneous imaging, spectroscopy, and spectro-polarimetry in the visible wavelength range.
- It can image the solar corona very close to the visible edge of the Sun (down to 1.05 times the solar radius), providing the closest-ever visible-light spectroscopic observations of Coronal Mass Ejections (CMEs).
Multi-Layer Study: It carries seven payloads designed to study the Sun’s atmosphere across its three layers: the Photosphere, the Chromosphere, and the Corona.
In-situ and Remote Sensing: It performs both remote sensing (looking at the Sun) and in-situ (measuring particles and fields at the L1 point) observations simultaneously, linking the cause (solar activity) with the effect (space weather).

What are Lagrange Points?

Lagrange Points (or L-points) are positions in space where the gravitational forces of two large orbiting bodies (like the Sun and Earth) and the centripetal force required for a small object to move with them precisely balance each other out.
These points are essentially “parking spots” where a spacecraft or small object can maintain a fixed position relative to the two large bodies with minimal fuel consumption for course correction.
Italian-French mathematician Joseph-Louis Lagrange first discovered these five specific points (L1 through L5) in the late 18th century as a solution to the “restricted three-body problem” in celestial mechanics.

Anatomy of Sun

The Sun is composed of two main sections: the Interior and the Atmosphere. The Sun’s activity, which drives space weather, is governed by its Solar Cycle.

Inner Layers (Interior)

These layers are where the Sun’s energy is generated and transported outward.

Core: The innermost region, where temperatures (~15 million K) and pressure are immense, driving nuclear fusion (converting hydrogen into helium) to create the Sun’s energy.
Radiative Zone: A thick layer surrounding the core where energy is transported by photons that bounce randomly from particle to particle.
Convection Zone: The outermost layer of the interior where energy is carried to the surface by vast, rising, and falling currents of hot plasma (like boiling water).

Outer Layers (Atmosphere)

These layers are visible and extend out into space, driven by the energy from the interior.

Photosphere: The visible surface of the Sun. It has a temperature of about 5,800 K and is marked by sunspots (cooler, dark regions created by intense magnetic fields).
Chromosphere: A thin layer above the photosphere that is slightly hotter and appears reddish during a total solar eclipse.
Corona: The outermost layer of the Sun’s atmosphere. It extends millions of kilometers into space, and surprisingly, is millions of degrees Celsius—much hotter than the photosphere. It’s the source of the solar wind.

The Solar Cycle and Space Weather

The Solar Cycle is a periodic, approximately 11-year cycle of increasing and decreasing activity on the Sun, driven by the generation and reorganization of its magnetic field.

Phase	Duration	Key Characteristics	Associated Events
Solar Minimum	Starts the cycle (approx. 11 years)	The Sun’s magnetic field is simple; very few or no sunspots are visible.	Low occurrence of major space weather events.
Solar Maximum	The peak of the cycle (midpoint)	The Sun’s magnetic field becomes highly complex and twisted, resulting in the maximum number of sunspots and active regions.	High frequency and intensity of major space weather events.

Associated Space Weather Events

Solar activity caused by the complex magnetic fields during the Solar Maximum includes:

Sunspots: Darker, cooler areas on the photosphere where intense magnetic fields inhibit the flow of heat. Their number is the main indicator of the solar cycle phase.
Solar Flares: Sudden, intense bursts of electromagnetic radiation (like X-rays and radio waves) released when magnetic field lines snap and reconnect near sunspot groups. They travel at the speed of light.
Coronal Mass Ejections (CMEs): Massive clouds of magnetized plasma and charged particles ejected from the corona into space. They are often, but not always, associated with solar flares. CMEs are the primary cause of severe geomagnetic storms on Earth.
The energy and particles released during these events can impact Earth, causing phenomena like auroras (Northern and Southern Lights) and potentially disrupting power grids, satellites, and communication systems (Space Weather).