EYE IN THE SKY

Telescope was invented by accident though there are many theories attached to it. In 1655 an unknown European spectacle maker had testified that his father had invented the telescope as early as 1590. As a child he saw the nearby church very close and bigger while playing with two types of glasses. He ran to his father who was also a spectacle maker in excitement and he fixed the glasses that way which was believed to be the first telescope in the world.

But a unique large telescope that focuses light with a slowly spinning bowl of liquid mercury instead of a solid mirror has opened its eye to the skies above India this month in the Himalayas. Such telescopes have been built before, but the 4-meter-wide International Liquid Mirror Telescope (ILMT) is the first large one to be purpose-built for astronomy, at the kind of high-altitude site at Devasthal Observatory. When a bowl of reflective liquid mercury is rotated, the combination of gravity and centrifugal force pushes the liquid into a perfect parabolic shape, exactly like a conventional telescope mirror— but without the expense of casting a glass mirror blank, grinding its surface into a parabola, and coating it with reflective aluminum.