125 years of Kodaikanal Solar Observatory

News Excerpt:

Tamil Nadu based Kodaikanal Solar Observatory (KoSO) is celebrating 125 years of groundbreaking research contributing significantly to the global scientific community.

About  Kodaikanal Solar Observatory (KSO)

  • The Kodaikanal Observatory is located in the beautiful Palani hills in Tamil Nadu. 
  • The observatory is owned and operated by the Indian Institute of Astrophysics.
  • It was established in 1899 as a Solar Physics Observatory when all the activities of the Madras Observatory were shifted to Kodaikanal. 

History of Solar observation in India:

  • The Madras Observatory was established in 1792 by the British East India Company to promote astronomy, geography and navigation in India.
    • Several important observations were made from Madras Observatory:
      • The spectroscopic observations taken during the total solar eclipse from Guntur in Andhra Pradesh in 1868 led to the discovery of helium, the second-most abundant element after hydrogen in the Universe.
      • For the first time, celestial and solar photography were attempted from the Madras Observatory during the total annual solar eclipse on December 12, 1871.
  • The first dedicated solar observations in India were recorded in 1878 from the Trigonometrical Survey Office in Dehradun.

Dedicated Solar Physics Observatory in Palani Hills:

  • Great Drought and famine of 1875-77
    • Scanty rainfall over south India during the winter monsoon of 1875 triggered one of the worst droughts the country had experienced till then.
    • The drought was thought to be due to multiple reasons – solar activity; cool Pacific Ocean conditions followed by a record-breaking El Nino (1877-1878); strong Indian Ocean Dipole and warm North Atlantic Ocean conditions.
  • Based on the evidence that solar activity was linked to the seasonal rainfall distribution over India, the specially constituted Famine Commission of the British Raj recommended that the Government of India take regular solar observations.
    • That gave the idea for an Indian solar observatory, ‘for carrying out systematic examinations and the study of changes in progress in the Sun and their co-relations with the larger features of Indian meteorology.’
  • Following the recommendation of the commission Kodaikanal was selected for the solar observatory due to its high altitude, clear skies, geographic isolation, and stable weather by Charles Michie Smith, a Physics Professor.
  • In 1895, Lord Wenlock, the then Governor of Madras, laid its foundation stone. By the end of the 1900s, the main observatory building and the two adjacent domes were built and ready to accommodate instruments.
  • The Madras Observatory was merged with the KoSO following the reorganisation of all Indian observatories by the Government of India on April 1, 1899. 

Important Scientific contributions of KoSO:

  • Since the early 20th century, the Kodaikanal Solar Observatory has continued to facilitate crucial research in solar as well as astrophysics. 
  • The radial motion of sunspots, better known as the Evershed Effect, was discovered from the sunspot observations made at KSO by John Evershed in 1909.
  • Until the end of World War II in 1945, it remained an observatory dedicated to solar physics. Thereafter, it expanded its ambit to study cosmic rays, radio astronomy, ionospheric physics, stellar physics and more areas. 
  • The continuous recording of the solar radio noise flux commenced in 1952 is considered the earliest solar radio observations in the country. 

Telescopes and instruments at KoSO:

  • KoSO houses a spectrum of advanced instruments like the H-alpha telescope to perform full disc imaging, a White light Active Region Monitor (WARM) with calcium and sodium filters to make full disc simultaneous observations of the photosphere and chromosphere layers of the Sun, a solar tunnel telescope, Full-disk Photoheliograph, Full-disk Spectroheliograph and more:

Importance of solar observation:

  • Being the primary source of energy, life on Earth is supported by the Sun. Any change on the solar surface or its periphery could significantly affect the Earth’s atmosphere.
    • Powerful solar storms and solar flares can be potentially harmful to Earth’s satellite-based operations, power grids and navigational networks.
  • The Kodaikanal Solar Observatory has been imaging the Sun for over a century now, and has a rich repository of data. 
    • This is extremely useful not only to reconstruct the Sun’s historic past but also to link its behavioural changes to better understand and predict its future and its impact on life on Earth and Space weather.