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International Liquid Mirror Telescope (ILMT)

2023 MAR 23

Preliminary   > Science and Technology   >   Global research projects and India   >   Global research projects and India

Why in news?

  • The Union Minister of Science & Technology has inaugurated Asia’s largest 4-metre International Liquid Mirror Telescope at Devasthal in Uttarakhand.

About International Liquid Mirror Telescope (ILMT):

  • The telescope is located at the Devasthal Observatory campus owned by Aryabhatta Research Institute of Observational Sciences (ARIES),Nainital in Uttarakhand.
  • The telescope has been set up by India in collaboration with Belgium, Canada, Poland and Uzbekistan.
  • It was designed and built in Belgium.
  • ILMT is the first liquid mirror telescope designed exclusively for astronomical observations and this is the largest aperture telescope available in the country at present and is also the first optical survey telescope in India.

Working of the telescope:

  • ILMT employs a 4-metre-diameter rotating mirror made up of a thin layer of liquid mercury to collect and focus light.
  • The metal mercury is in liquid form at room temperature and at the same time highly reflective. It is ideally suited to form such a mirror.
  • The telescope is designed to survey the strip of the sky passing overhead each night, allowing it to detect transient or variable celestial objects such as supernovae, gravitational lenses, space debris and asteroids.
  • While scanning the strip of the sky every night, the telescope will generate nearly 10-15 Gigabytes of data and the Big Data and Artificial Intelligence/Machine Learning (AI/ML) algorithms will be implemented for classifying the objects observed with the ILMT.
  • The data will be analyzed quickly to discover and discern variable and transient stellar sources.

Liquid mirror telescope v/s Conventional telescopes:

  • Observation:
    • A conventional telescope is steered to point towards the celestial source of interest in the sky for observations.
    • The liquid-mirror telescopes, on the other hand, are stationary telescopes that image a strip of the sky which is at the zenith at a given point of time in the night.
    • In other words, a liquid-mirror telescope will survey and capture any and all possible celestial objects — from stars, galaxies, supernovae explosions, asteroids to space debris.
  • Focus:
    • Conventional telescopes have highly polished glass mirrors — either single or a combination of curved ones — that are steered in a controlled fashion to focus onto the targeted celestial object on specific nights. The light is then reflected to create images.
    • As opposed to this, the liquid-telescope is made up of mirrors with a reflective liquid, in this case, mercury — a metal which has a high light-reflecting capacity.
    • The mercury will spread as a thin layer in the container forming a paraboloid-shaped reflecting surface which will now act as the mirror. Such a surface is ideal to collect and focus light.
  • Operational time:
    • While conventional telescopes observe specific stellar sources for fixed hours.
    • ILMT will capture the sky’s images on all nights.
    • For protecting it from moisture during monsoon, the ILMT will remain shut for operations between June and August.


Recently International Liquid Mirror Telescope was established at Devasthal in Uttarakhand. Which of the following statements are correct regarding the telescope?

1. It is largest liquid mirror telescope in Asia

2. The telescope uses mercury element to employ as a reflective and mirror surface

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2