A new telescope facility atop a mountain in the Himalayan range will now keep a watch on the overhead sky to identify transient or variable objects such as supernovae, gravitational lenses, space debris, and asteroids.


What is it?

  • A liquid mirror telescope, as its name suggests, uses a liquid, not aluminised glass, as its primary mirror.
  • The liquid, usually mercury, is poured into a rotating dish.
  • The rotation creates two fundamental forces that act on the mercury — gravity and inertia.
  • Gravity pulls down on the liquid surface, while inertia pulls the liquid sideways at the edge of the dish.
  • As a result, the liquid forms a uniform and perfect parabola, the ideal reflecting surface for a telescope.
  • Best of all, the liquid mirror surface remains smooth and flawless with little or no maintenance.
  • If the liquid is disturbed, gravity and inertia will act on the liquid to return it to its original state.


History of LMT

  • Ernesto Capocci, an Italian astronomer, was the first person to describe how an LMT might work in 1850.
  • Modern astronomers learned that the image quality of an LMT was greatly improved if a thinner layer of mercury was used, so today’s LMTs use a one-millimetre layer of mercury.


How is LMT different from Optical Telescope?

  • An optical telescope is a telescope that gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic image sensors.
  • Unlike optical telescope, an LMT remains stationary as it cannot be turned and pointed in any direction.
  • It “stares” at the zenith and watches the sky as the Earth rotates, thereby giving a view of different objects.


About Devasthal LMT

  • India’s first liquid-mirror telescope, which will observe asteroids, supernovae, space debris and all other celestial objects from an altitude of 2,450 metres in the Himalayas, has seen its first light.
  • It has now entered the commissioning phase and will start scientific observations by October, 2022.
  • It is established on the campus of the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital, Uttarakhand.
  • Known as the International Liquid Mirror Telescope (ILMT), it is the only liquid-mirror telescope operational anywhere in the world.
  • It will also hold the unique tag of being the maiden liquid-telescope globally to be designed exclusively for astronomical purposes.


Why India’s majority telescopes are stationed at Devasthal Observatory?

  • This site was chosen after an extensive site characterisation conducted during 1980 – 2001 in the central Himalayan range.
  • The main advantages of Devasthal site are in its dark skies, sub-arcsec seeing, low extinction and at the same time being easily assessable and manageable.
  • In total, 41,692 square meter of land has been transferred to ARIES from Uttarakhand Government which includes roads, base camp area and telescope site.