100 years of Kodaikanal solar data reveal how the Sun's surface tracks its 11-year activity cycle

📌 Summary:

• Scientists at the Indian Institute of Astrophysics (IIA), an autonomous institute under DST, used 100+ years of Kodaikanal Solar Observatory data to study how the Sun's convective network tracks the 11-year solar cycle
• The Sun transports energy via convection, forming granulation and large-scale supergranulation network cells (~30,000 km wide, ~24-hour lifetimes)
• The team analysed 34,000 Ca II K images (archive from 1907), measuring supergranular lane widths and intensities
• Both correlate strongly with sunspot numbers, peaking around ±(11–22)° latitude
• Lane-width correlations peak at solar maximum, while intensity correlations lag 1.25–1.5 years after maximum — a latitude-dependent time lag
• Findings, published in the Astrophysical Journal Letters, aid future solar-cycle prediction

🎯 UPSC Relevance: GS3 Science & Technology — solar physics, indigenous long-term astronomical research

📝 Prelims Facts:

• Kodaikanal Solar Observatory holds India's oldest continuous solar data series (from 1907)
• IIA is an autonomous institute under the Department of Science and Technology (DST)
• The solar activity cycle is about 11 years; study used Ca II K spectroheliograms

🔑 Key Term: Supergranulation — large-scale convective cells (~30,000 km) on the Sun's surface that form a network pattern via magnetic flux concentration