Innovation Ecosystem in India

125 years of Kodaikanal Solar Observatory


From UPSC perspective, the following things are important :

Prelims level: Kodaikanal Solar Observatory (KoSO)

Mains level: NA

Why in the news?

This year marks 125th Year of the Kodaikanal Solar Observatory (KoSO).

About Kodaikanal Solar Observatory (KoSO)

  • The idea for an Indian solar observatory emerged in the late 19th century, with then government sanctioning the establishment of the Solar Physics Observatory in Kodaikanal in August 1893.
  • Kodaikanal in the Palani hills of Tamil Nadu was chosen as the site for the observatory due to its favorable atmospheric conditions, following surveys conducted by Charles Michie Smith.
  • The foundation stone for KoSO was laid by Lord Wenlock, the then Governor of Madras, in 1895.
  • Systematic observations at KoSO began on March 14, 1901.
  • KoSO initially housed instruments for solar observations, including telescopes for examining sunspots, prominences, and solar radiations.
  • Presently, KoSO houses advanced instruments like the H-alpha telescope and the White light Active Region Monitor (WARM) for high-resolution solar imaging.

Do you know?

  • The Bhavnagar Telescope, named after the Maharaja of Bhavnagar, was one of the more famous instruments at KoSO during the early decades of its operation.
  • A 15cm telescope was used to capture solar images onto a photographic film or plate.
  • Solar magnetic plages and prominences were recorded since 1911, taken on photographic films and plates.

Historical Perspective

  • Ancient Legacy: Throughout history, seafarers, mathematicians, astronomers, and physicists have meticulously studied the Sun and its celestial phenomena.
  • British Era Initiatives: In 1792, the British East India Company established the pioneering Madras Observatory, marking a significant milestone in astronomical research in the region.
  • Madras Observatory’s Legacy: The Madras Observatory documented crucial astronomical observations during 1812-1825, laying the groundwork for solar research in India.
  • Shift to Systematic Observations: Dedicated solar observations commenced in 1878, fostering a deeper understanding of solar phenomena.
  • Advancements in Methodology: The adoption of systematic observational techniques paved the way for more comprehensive and detailed studies of the Sun’s behavior.

Need for such Observatory

  • Great Drought of 1875-1877: This event triggered by scanty rainfall, propelled the need for comprehensive solar studies to comprehend its implications on weather patterns.
  • India’s Geographical Significance: India’s drought was part of a larger global phenomenon, affecting several countries and leading to widespread famine.
  • Scientific Inquiry: Scientists recognized the potential role of solar variability in influencing climatic patterns, prompting inquiries into the Sun’s behavior and its correlation with environmental phenomena.

Scientific Endeavors of KoSO

  • The observatory made significant contributions to solar physics, including the discovery of the radial motion of sunspots, known as the Evershed Effect.
  • Over time, KoSO expanded its research areas beyond solar physics to include cosmic rays, radio astronomy, ionospheric physics, and stellar physics.
  • In April 1971, KoSO was brought under the Indian Institute of Astrophysics (IIA), Bengaluru, as part of the separation of astrophysics from the India Meteorological Department (IMD).

Repository of the KoSO

  • Between 1904 and 2017, all solar observations were traced onto photographic films and plates
  • A new telescope mounted with CCD cameras has taken over and, since 2017, continued to observe the Sun.
  • Digitization of the records was initiated in 1984 by Prof J C Bhattacharyya, and others continued the effort.
  • KoSO is now home to a digital repository of a whopping 1.48 lakh solar images adding up to 10 terabyte of data.
  • These include 33,500 white-light images (showing sunspots), 45,000 images of the Ca II K spectral line (which reveals plages), and 70,000 H-alpha photographic plates that show prominences.



On 21st June, the Sun-

(a) does not set below the horizon at the Arctic Circle

(b) does not set below the horizon at Antarctic Circle

(c) shines vertically overhead at noon on the Equator

(d) shines vertically overhead at the Tropic of Capricorn


Practice MCQ:

Which of the following statements correctly describes the ‘Evershed Effect’ in Sun?

(a) It refers to the bending of light waves around obstacles, demonstrated by the diffraction pattern observed in a single-slit experiment.

(b) It is the phenomenon of a magnetic field being generated by the motion of charged particles in the convective zone of the Sun.

(c) It describes the deflection of moving charged particles, such as electrons, in a magnetic field, leading to the creation of an electric potential difference.

(d) It is the radial flow of gases in the Sun’s outer atmosphere, observed as a redshift in the spectrum of light emitted by the photosphere.

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