Indian Astronomical Observatory | Where the Stars Must Not Twinkle : Daily Current Affairs

Date: 10/10/2022

Relevance: GS-3: Science and Technology- developments and their applications and effects in everyday life.

Key Phrases: Indian Astronomical observatory, Hanle Dark Sky Reserve (HDSR), High Altitude Gamma Ray Telescope (HAGAR), Himalayan Chandra Telescope (HCT), Major Atmospheric Cherenkov Experiment Telescope (MACE)

Context:

  • Recently, the Department of Science & Technology (DST) has announced the setting up of India’s first Dark Sky Reserve in Hanle, Ladakh.

What is a Dark Sky Reserve?

  • The International Dark Sky Association (IDSA) defines a dark sky reserve as “a public or private land of substantial size (at least 700 km²) possessing an exceptional or distinguished quality of starry nights and nocturnal environment, and that is specifically protected for it’s scientific, natural, educational, cultural heritage, and/or public enjoyment.”
  • Since 1988 the status of International Dark Sky Reserve (IDSR) has been accredited by the International Dark-Sky Association (IDSA), a U.S.-based non-profit organization.
  • The Hanle Dark Sky Reserve (HDSR) will come up within the Changthang Wildlife Sanctuary, Leh district, Ladakh.
    • The Changthang sanctuary is situated 4,500 metres above sea level, which makes it a perfect host for telescopes.
  • Requirements of Dark Sky Reserve
    • It requires a “core” area with clear sky without any light pollution which can enable telescopes to see the sky in its natural darkness.
    • The core area should be complemented with a “peripheral” or “buffer” area that supports dark sky values in the core while receiving the same benefits.
  • At present, there are 20 dark sky reserves around the world, seven in the United Kingdom; four in France are the most in a single country.

Indian Astronomical observatory : Historical background

  • Indian astronomers in India, led by R. Rajamohan, discovered an asteroid that was later named 4130 Ramanujan.
    • It was the first time in 104 years that asteroids were discovered from India.
  • They carried out these discoveries using the 45-cm Schmidt telescope, which was housed on the Javadi hills in Kavalur, Tamil Nadu and the spot is today called as Vainu Bappu Observatory.
  • The Vainu Bappu Observatory was situated at 750 metres above sea level, located amid a forest and offered fairly unobstructed vistas of the night sky making it suitable for an observatory.
  • Although Kavalur’s geography put it in the path of both (South-west and North-East) monsoonal clouds forcing the observatory to often shut down for months
    • Rain clouds absorb starlight and radiation from cosmic objects, preventing them from being caught on the telescopes of cameras.
    • Hence, the search began in the early 1980s for a place least affected by the monsoon.

Suitable conditions for an Astronomical observatory

  • It should catch the faintest of stars’ radiation that often lie outside the range of visible light.
    • It is necessary to be able to detect stars or traces of cosmic phenomena, such as supernovae or nebulae from light years away.
  • Dry atmosphere is preferred because such radiation is easily absorbed by water vapour and so a telescope high above ground where the atmosphere is drier is helpful.
    • A dry, high-altitude desert is in many ways the ideal location
    • Such terrain is difficult and quite inaccessible.
    • After several expeditions and teams to different parts of the Himalayas and finally Hanle, Ladakh was chosen as it provides the ideal conditions.

The Hanle Astronomical observatory

  • Geography and Climatic conditions
    • The Indian Astronomical Observatory (IAO) stands on the mountain called Digpa-Ratsa Ri, aka Mt Saraswati, Hanle in south-eastern Ladakh union territory at an altitude of 14,000 ft above sea level.
    • Hanle site is as dry as the Atacama Desert in Chile and much drier than Devasthal (Uttarakhand) and has around 270 clear nights in a year.
  • Observatory Set-up
    • The IAO at Hanle has one of the world's highest sites for optical, infrared and gamma-ray telescopes.
    • According to the Department of Science and Technology the setup will give best results because it has some advantages such as
      • Clear nights
      • Minimal light pollution
      • Background aerosol concentration
      • Extremely dry atmospheric condition
      • Uninterrupted monsoon
    • Such conditions are considered crucial for astronomers to build huge telescopes and plan for future observatories and predict how they will vary with time.
  • The MACE Telescope
    • The 21 meter diameter telescope at IAO is called the Major Atmospheric Cherenkov Experiment Telescope (MACE)
    • It is currently the ninth highest optical telescope in the world and is operated by the Indian Institute of Astrophysics, (IIA) Bangalore.
    • The goal of MACE is to detect Cherenkov radiation from space.
      • Cherenkov radiation is a special kind of light from gamma rays, or the most energetic sources of radiation, that can result from dying stars or several galactic events.
  • Other important telescopes and equipment at the IAO
    • High Altitude Gamma Ray Telescope (HAGAR): It is an array of seven telescopes, operational since September 2008 and constitutes the first phase of the Himalayan Gamma-Ray Observatory (HIGRO) project.
      • It also looks at Cherenkov radiation, although at a lower range of energies.
    • Himalayan Chandra Telescope (HCT): It is the metallic capsule, the highest of the observatories, the oldest and active since 2000.
      • An optical-infrared telescope with a 2-metre lens, designed to detect light from the visible range of the electromagnetic spectrum as well as that just below it, or the infra-red spectrum.
      • The second capsule, situated slightly lower than the HCT, is the GROWTH-India telescope, a 70-cm telescope made by IIA and IIT Mumbai is equipped to track cosmic events, such as afterglows of a gamma ray burst or tracking the path of asteroids.
  • Operations
    • The IAO telescopes, however, can be controlled remotely via a satellite link.
    • Irrespective of weather, the astronomers at the IIA’s Centre for Research and Education in Science and Technology (CREST), Bengaluru can manoeuvre the HCT to face their desired spot of sky.
    • The other instruments too are equipped to be remotely controlled.
  • Significance of the IAO
    • The IAO provides a platform to observe a range of cosmic phenomena and investigate the mysteries of the universe.
    • Owing to a wide span of frequencies covered collectively, the IAO provides multiple advantages.
    • Telescopes with small diameters generally can track a greater swath of sky but those with larger diameters can peer deeper when trained towards desired locations.
  • Recent developments
    • In recent years, these telescopes have helped gain a better understanding of a system of Earth-sized planets orbiting the TRAPPIST-1 star, about 40 light years away from Earth, as well as gravitational waves that resulted from the collision of neutron stars from a billion years ago.

Amidst the bright lights challenges are many

  • High Altitude and adverse weather
    • Atmospheric oxygen is low, making one prone to mountain sickness.
    • Desiccated air translates to sub-zero winters for at least six months of the year.
    • Cold, windy nights, and with no access to the electric grid from April to Sep.
  • Light pollution
    • Artificial light from cities and home electrification have obscured the natural night sky and for astronomy, the artificial sources of light are contaminants.
    • Recent studies show that clouds, the biggest reflectors of sunlight, scatter artificial light from ground-based sources, amplifying light pollution
    • Light beams from vehicles may affect sensors of telescopes and this will lead to inaccuracy of collected data which may result in loss of scientific data.
  • There is a dearth of basic infrastructure development in the Hanle and nearby areas.

Conclusion

  • The declaration of Hanle as India’s first Dark Sky Reserve is a step in the right direction; it will prevent to a large extent the damage posed by light to the observatory and related research will get a boost.
  • The announcement also seeks to provide dark curtains to the locals so that the impact of residential lights is minimized.
  • To promote Astro-tourism, villages around Hanle will be encouraged to promote homestays equipped with telescopes that visitors can use to view the night sky.
  • Therefore the need of the hour is to take all the stakeholders into the confidence to make it a win-win situation for all involved.

Source: The Hindu

Mains Question:

Q. What do you know about the Indian astronomical observatory? Which types of conditions are required to establish astronomical observatories? What is a dark sky reserve? How can a dark sky reserve help in overcoming challenges faced by astro-scientists and researchers? (250 words).