Asia’s Largest Liquid-Mirror Telescope Installed in Devasthal of Nainital

The country’s first Liquid-mirror Telescope (ILMT) located at Devasthal in Nainital, India has entered its commissioning phase. It will also be able to start scientific observations in October this year. It is situated at an altitude of about 8000 feet i.e. 2450 meters above sea level.

It is Asia’s largest liquid-mirror telescope and will observe supernovae, gravitational lenses, space debris and asteroids in the sky.

It has been produced in collaboration with Belgium and Canada. A total of Rs 40 crore has been spent in this project. Astronomers from Aryabhatta Research Institute of Observational Sciences (ARIES), Advanced Mechanical and Optical Systems (AMOS) Corporation, Canada and The Center Spatial de Liège, Belgium have collaborated to make it.

It has been established in the premises of Devasthal Observatory of Aryabhatta Research Institute of Observational Sciences (ARIES) located in Nainital. The International Liquid-mirror Telescope (ILMT) is the only Liquid Mirror Telescope operating anywhere in the world. As such it will hold the distinction of being the first liquid telescope globally to be designed specifically for astronomical purposes.

Thus ILMT will be the third telescope to be operated from Devasthal. Earlier there operated a 3.6 meter standard optical telescope (Devasthal Optical Telescope-DOT) and a 1.3 meter Devasthal Fast Optical Telescope.

ILMT is fitted with a rotating mirror with a diameter of four meters. This mirror is made of a thin film of liquid mercury that will collect and then focus the light. In this way it is different from conventional telescopes which have glass mirrors to capture the light. However, the limitation of the ILMT is that the instrument cannot be tilted.

According to experts, the International Liquid-mirror Telescope will work for five years and will take images every night. But it will not be able to work in the months of June, July and August. Because it is monsoon time and hence this telescope will need to be saved.

What is a Liquid-mirror Telescope?

As the name suggests, liquid is used instead of the traditional glass. This liquid is usually mercury.

This liquid is put inside the rotating dish. When this dish rotates, two types of forces start acting on the liquid. One is the force of inertia and the other is the force of gravity. As you would know that inertia opposes the state of matter whether it is in a stationary state or in a state of motion.

So when the dish rotates, inertia pulls the fluid to the edge of the dish, while on the other hand, the force of gravity pulls the fluid downward.

Due to these two forces, the fluid takes the form of a uniform and perfect parabola, which is the ideal reflecting surface for a telescope.

The special thing about the surface of a liquid-mirror telescope is that very little or no cost is spent in its maintenance. Also, if for some reason the telescope is shaken, then after some time again that fluid comes in its position due to inertia and gravity.