- Why in news
- On 30 June 2026, the Ministry of Science & Technology reported that Indian Institute of Astrophysics scientists studied the thermal state of ICMEs at Earth over 29 years. The work may improve space weather forecasting.
- What it is
- An Interplanetary Coronal Mass Ejection (ICME) is a large cloud of magnetised plasma thrown out from the Sun's corona that travels through interplanetary space. When one is directed at Earth, it can disturb Earth's magnetic field and cause a geomagnetic storm. These storms can affect satellites, GPS, radio links, aviation routes and power grids, and also cause auroras.
- First long-term thermal study
- The IIA team did the first long-term statistical study of ICME thermal behaviour at 1 AU, covering 1995 to 2024 and three solar cycles.
- Polytropic index
- The team used the polytropic index, which shows how pressure/temperature vary with density, to judge the thermal state of each magnetic ejecta.
- Heating signatures
- About 45% of magnetic ejecta showed heating at 1 AU, mostly near solar maximum. This goes against the assumption that CMEs only cool as they expand.
- Link to geoeffectiveness
- The most geoeffective storms were linked to ICMEs in a heating state (low Gamma), with strong magnetic fields and low plasma beta.
- L1 data source
- The study used in situ solar wind data from satellites at L1, about 1.5 million km from Earth towards the Sun, via the OMNI database.
- Aditya-L1
- India's Aditya-L1 solar mission is placed at the Sun-Earth L1 point. Its data will be used in future work.
Don’t confuse with ICME vs solar flare: A CME is a bulk ejection of magnetised plasma. A solar flare is a burst of electromagnetic radiation. Flares reach Earth in about 8 minutes, while CMEs take days.
Don’t confuse with CME vs ICME: A CME is the eruption seen at the Sun. ICME is the term for it once it travels through interplanetary space, as measured near Earth.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- Better forecasts can protect satellites, GPS, aviation routes and power grids from severe geomagnetic storms.
- It shows Indian scientists contributing to heliophysics and supports use of Aditya-L1 data.
Problems
- Thermal signatures can be measured only in situ near L1, giving short warning time before a storm hits.
- Predicting thermal state from remote observations earlier in the journey is not yet established.
Way forward
- Combine Aditya-L1 coronagraph and solar wind data to track thermal evolution closer to the Sun and refine forecast models.
Put in your answer
Solar cycle 25 peak: The peak of the current solar cycle 25 was in 2025, so more ICMEs and storm risk are expected around this period.
Solar activity cycle: Solar activity follows an 11-year cycle, and more ICMEs occur during its maxima.
- 2024Mains GS1 · Q15Explain aurora australis/borealis and their triggering mechanisms
- 2025Prelims Q33Correct statements on solar flares, CMEs and Earth's rotation
- 2022Prelims Q40Possible effects of a major solar storm reaching Earth
UPSC’s own questions that come close to this issue, from our Prelims and Mains banks.
No practice question for this one; the card may still help an answer. Why: Space weather concepts are testable (sci_tech concept questions are 36 of 57), but this is a research finding; a card suffices.
Worth revising until Prelims 2028: most news questions come within two years of the event.