Subject: GS 3: Science and Technology
Context: Scientists have found that the Sun’s upper atmosphere rotates faster than its visible surface, providing new insights into solar dynamics and space weather forecasting.
- Research Methodology: Researchers from Aryabhatta Research Institute of Observational Sciences (ARIES), Udaipur Solar Observatory (USO)–Physical Research Laboratory (PRL) and Ahmednagar College used observations from Japan’s Nobeyama Radioheliograph and a two-dimensional image-correlation technique to measure solar atmospheric rotation.
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Key Findings of the Study
- Faster Atmospheric Rotation: The Sun’s upper atmosphere rotates faster than its visible surface, with rotation speed increasing with height, challenging conventional expectations based on angular momentum conservation.
- Differential Rotation: The Sun’s equator rotates faster than its poles, completing a rotation in about 25 days compared with nearly 35 days at the poles.
- Solar Activity Link: Atmospheric rotation slows slightly during periods of increased solar activity and higher sunspot numbers, suggesting a connection with the solar cycle.
Aryabhatta Research Institute of Observational Sciences (ARIES)
- About: ARIES is an autonomous research institute under the Department of Science and Technology (DST), Government of India, specialising in astronomy, astrophysics and atmospheric sciences, with facilities in Nainital and Devasthal, Uttarakhand.
- Major Facilities: It operates the 3.6-metre Devasthal Optical Telescope (DOT) and the International Liquid Mirror Telescope (ILMT), supporting advanced ground-based astronomical observations.
- Origin: Established in 1954 as the Uttar Pradesh State Observatory (UPSO) in Varanasi, it was later relocated to Nainital and renamed ARIES in 2004 as an autonomous central government institution.
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Structure of the Sun
- Core: The innermost layer where nuclear fusion occurs, converting hydrogen into helium and generating the Sun’s energy. Temperatures reach nearly 15 million°C.
- Radiative Zone: Energy from the core moves outward mainly through radiation, with photons undergoing repeated absorption and re-emission, making energy transfer extremely slow.
- Convective Zone: Hot plasma rises toward the surface while cooler plasma sinks, creating convection currents that transport energy outward.
- Photosphere: The visible surface of the Sun from which most sunlight is emitted. It contains relatively cooler, darker regions known as sunspots.
- Chromosphere: A thin, reddish atmospheric layer above the photosphere, visible prominently during a total solar eclipse.
- Corona: The Sun’s outermost atmospheric layer, consisting of extremely hot, tenuous plasma and extending millions of kilometres into space.
Impact of Solar Activities on Earth (UPSC Prelims 2023)
- Power Grids: Geomagnetic storms can induce electrical currents, potentially damaging transformers and causing power disruptions.
- Satellites: Solar activity can increase atmospheric drag and damage spacecraft electronics.
- Communication: Solar flares can disturb the ionosphere, heavily impacting shortwave radio disrupting HF radio and GPS signals.
- Auroras: Charged solar particles interacting with Earth’s magnetic field produce spectacular auroras near the polar regions.
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The findings enhance understanding of solar dynamics and could improve space weather forecasting, helping mitigate disruptions to satellites, communications, navigation systems and power infrastructure.
31 Jul 2026
