Sometimes distortions can be a useful thing. That is what one learns from the new mirror dome projection unit at the Jawaharlal Nehru Planetarium in the city.
The unit, bought from the Swinburne University, makes use of a convex mirror in tandem with a digital projector and the Mackintosh to obtain a wide view observation.
Unlike the earlier system which made use of four projectors to project slides onto various parts of the dome and still left parts of the dome unused, the present one makes use of the whole 15 metre wide dome with one projector, explained Madhusudhan, educator at the Planetarium.
Reflections from a mirror are usually distorted. The system makes use of anamorphic technique made use of by 15th century European artistes to de-distort images. If already distorted images are seen through such mirrors, the distortion disappears!
Fish eye images from fish-eye lenses (that give very wide fields of view but distort the images in the process) are beamed onto the mirror that projects cleaned up images, he said. This correction to rectilinear images are done using computer programmes.
Fisheye lenses were first used by astronomers to capture the entire hemisphere of the night sky with one shot. Since then they have been used by photographers, eco-scientists, etc.
Using this technique the projection unit at the Planetarium brings to its viewers a thrilling journey through the universe, using the images generated by the Hubble telescope since its launch in 1990.
Orbiting the earth at a height of 570 kilometres in a circular path, Hubble can take clear shots of space unobstructed by the dense atmosphere. Its powerful telescope can detect a nail on earth! That is nothing considering that it can peer into the origins of the universe, almost 13 billion years away.
It has shown that blackholes are not rarities, detected solar systems by sifting aside the curtains of stellar dust, detected baby booms in globular clusters, seen a 10 bn year old star burst, taken over 700,000 images, and chugs along alone up there!
Check out at the Planetarium the new programme - Hubble’s Vision.
