India’s liquid reflecting telescope ready to observe the night sky

The International Liquid Mirror Telescope in its building in the Himalayas.

The International Liquid Mirror Telescope in its building in the Himalayas.
photo: Jean Surdej

A new telescope is set to observe the night sky high in the Himalayas. The device has a 4-meter lens, but here’s the kicker: it’s made of liquid mercury, a material rarely used in astronomical imaging.

Known as the International Liquid Mirror Telescope (ILMT for short), the device essentially consists of a layer of liquid mercury floating on a wafer-thin layer of compressed air. The mercury rotates, taking on a parabolic shape – useful for focusing light from the night sky. By placing a camera at the focal point of the paraboloid, astronomers can then image objects in the sky.

At first glance, the telescope’s mirror appears to be an ordinary reflective surface. But in reality it is made of liquid meticulously transported up the mountain by a company specializing in hazardous materials. As long as nobody tries to drink However, the telescope’s mirror is perfectly safe — and according to the ILMT team, it’s an affordable alternative to other telescope mirror materials.

“The main advantage is the relatively low cost of a large liquid mirror compared to a large conventional telescope mirror,” Paul Hickson, an astronomer at the University of British Columbia who works on liquid mirror technologies, said in an email to Gizmodo. “For example, the cost of the ILMT is about a tenth of the cost of the 3.6 meter [11.8-foot] Devasthal Optical Telescope — a conventional telescope of about the same size and in the same place.”

And this place is quite sublime. The telescope is over 8,000 feet above sea level on the Indian side of the Himalayas. It will study a strip of sky directly overhead that contains hundreds of thousands of galaxies and several thousand quasars, Hickson said. (Quasars are very active galactic nuclei that are bright in the night sky.)

By imaging the sky at night — directly overhead, where there is least atmospheric noise — astronomers can deduce which objects are changing in the sky over time, whether they’re new supernovae, asteroids passing in front of glowing objects, or even passing black holes that curve that light off sources behind.

“We estimated that 50 new cases of multi-imaged quasars should be detected in the ILMT’s field of view,” Jean Surdej, an astrophysicist at the University of Liège in Belgium and project leader, said in an email to Gizmodo.

The telescope saw it is First light in April, but scientific observations will not begin until later this year. when it is fully functional, The telescope collects 10 gigabytes of data every night. Given the mercury nature of supernovae and gravitational lenses, it is appropriate that the ILMT captures these events with mercury.