Kolkata: When the annular solar eclipse takes place December 26, sky watchers should use safe viewing equipment and proper techniques to view the celestial event as the infrared and ultraviolet rays of the Sun can cause severe retinal damage, senior astronomer Debiprosad Duari said Wednesday.
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the Sun for a viewer on Earth.
“An annular solar eclipse takes place when the moon’s apparent diameter is smaller than that of the Suns and blocks most of its light. This causes the Sun to look like a ring (annulus) of fire, Duari, the Director, Research and Academic of MP Birla Institute of Fundamental Research, MP Birla Planetarium, informed.
Partial phases of the solar eclipse will be visible from all over the country in varying magnitude depending upon the geographical position.
“One should not look directly to the Sun for even a short period without proper protection. Even when 99 per cent of the surface of the Sun is covered by the moon during partial eclipse, the remaining light is still intense enough to damage the eye,” Duari informed.
“Proper solar filters with certified appropriate optical density against radiation which are safe to the eyes should be used in front optical devices and the naked eye,” Durai said.
“Aluminised mylar films of approved thickness and transmittivity coated with black polymer are the safest for use in solar goggles that one generally uses for eclipse viewing. Welders glass number 14 is also a safe material as solar filter to view the eclipse,” he added.
According to him, the best method to view the solar eclipse will be to use a pinhole camera or a telescopic projection on a suitable surface.
Use of unsafe filters like smoked glass, polarizing filter, sun glasses, photographic neutral density filters, colour films are not advised to view the solar phenomenon.
Thursday’s eclipse will be visible in Saudi Arabia, Qatar, United Arab Emirates, Oman, India, Sri Lanka, Malaysia, Indonesia, Singapore, Northern Mariana Islands, and Guam.
In the Indian sub-continent, the annularity phases will be seen within a narrow path grazing the southern Indian peninsula through Karnataka, Kerala and Tamil Nadu before crossing the Bay of Bengal for northern Sri Lanka.
The people of the southern part of the country will be fortunate to see a greater part of the partial solar eclipse because of the geometry of the eclipse path. But every Indian will get an opportunity to see at least a partial eclipse. In India the maximum duration of the annularity phases will be just over three minutes, said Duari.