CHENNAI: An annular eclipse of the Sun will take place on June 21 and several parts of Tamil Nadu will be able to witness the event albeit partially.
S Soundararajaperumal, executive director of the Tamil Nadu Science and Technology Centre, told The New Indian Express, "In Chennai, only a partial phase of the eclipse will be visible. However at maximum eclipse, 34% of the disk of the Sun will be covered by the Moon. In Chennai, the eclipse will begin at 10:22 am and end at 1.41 pm. Maximum eclipse will be at 11:58 am."
He said this is a rare event. Earlier, on January 15, 2010 and on December 26, 2019, India witnessed an annular eclipse. "On June 21, India will have another annular eclipse. After this, India will have an annular eclipse again only on May 21, 2031," he added.
The annular phase of the eclipse will be visible in places like Chamoli, Dehradun, Joshimath, Kurukshetra, Sirsa, Suratgarh in northern India. In Tamil Nadu, partial phases will be visible in
Chennai, Vellore, Trichy, Coimbatore, Madurai and Kanyakumari.
Soundararajaperumal said it is unsafe to look at the Sun directly. Even during a partial or annular eclipse one should not attempt to view the Sun without any eye protection. Permanent eye injury or loss of eyesight will result.
"The safest and most inexpensive method for observing the Sun, is by projection. Binoculars or a small telescope mounted on a tripod can also be used to project a magnified image of the Sun onto a white card, but care must be taken to ensure that no one looks through the device. The main advantage of the projection methods is that nobody is looking directly at the Sun. The Sun can only be viewed directly when filters specially designed to protect the eyes are used," he said.
How does an annular eclipse occur?
By an extraordinary coincidence, the Moon appears as big as the Sun in the sky. This is why during a total eclipse of the Sun, the Moon completely blocks the Sun. This is due to the fact that, though the Moon is smaller than the Sun, it is nearer to us. That is the Sun is 400 times bigger than the Moon at the same time it is 400 times farther than the Moon.
The moon moves in an elliptical orbit around the Earth. Due to this, the Moon sometimes comes closer to the Earth and sometimes goes farther to the Earth. The Moon’s distance from Earth (center-to-center) varies with mean values of 363,396 km at perigee (closest) to 405,504 km at apogee (most distant). When it is farther away, its apparent size as seen from the Earth slightly diminishes.
During this time if an eclipse of the Sun takes place, the Moon will not be able to completely block the entire Sun. An annulus of the outer regions of the Sun will still be visible during the maximum eclipse. So this kind of eclipse is known as an annular eclipse.