A woman observes an annular solar eclipse in Siak, Indonesia, in December 2019. Photo: Reuters/Willy Kurniawan.
New Delhi: A rare celestial event – an annular solar eclipse, known more popularly as a ‘ring of fire’ eclipse – will be visible this Sunday. The first solar eclipse of this year takes place on the summer solstice, which is the longest day in the Northern Hemisphere. While people living along the path of the annular eclipse passing through Anupgarh, Suratgarh, Sirsa, Jakhal, Kurukshetra, Yamunanagar, Dehradun, Tapowan and Joshimath will be able to see the annular phase, people in the rest of India will be able to witness a partial eclipse.
When the Moon comes between the Sun and Earth, the shadow falls on Earth’s surface. As seen from Earth, the Sun is entirely covered by the Moon for a brief period. Those places that are engulfed by the dark, dense umbral shadow of the Moon experience a total solar eclipse. In the regions that plunge into the soft, diffused penumbral shadow of the Moon experience a partial eclipse.
When the Sun, Moon and Earth are not perfectly aligned, we have a partial eclipse. When the three celestial bodies happen to be in a straight line, we have a total solar eclipse.
“An annular solar eclipse is a particular case of the total solar eclipse. Like the total solar eclipse, the Moon is aligned with the Sun. However, on that day, the apparent size of the Moon happens to be a wee smaller than the Sun. Hence the Moon covers the central part of the Sun, and the rim of the Sun appear like a ‘ring of fire’ in the sky for a very brief moment,” Samir Dhurde, of the Inter-University Centre for Astronomy and Astrophysics, Pune, told India Science Wire.
The distance between Earth and the Moon at the moment of the eclipse can dictate the type of eclipse. The distance between Earth and the Moon is always changing due to the egg-shaped elliptical orbit of the Moon. This means there will be times where it is closer to Earth and appears to be slightly bigger in the sky – and other times when it is farther away and appears somewhat smaller in the sky.
Coincidentally, during the eclipse that takes place on June 21, the apparent size of the Moon will be smaller than that of the Sun by 1%.
At the onset of the solar eclipse, the Sun gives a characteristic appearance of a bitten apple.
A small part of the Sun is covered by the disc of the Moon. After that, slowly and steadily, the disc of the Moon covers a larger and larger part of the Sun. On a narrow track that the Moon’s shadow traces on Earth during an annular solar eclipse, people can see the Moon ‘moving across’ the Sun and covering the central part. As the Moon is not able to block out the entire Sun, a bright ring of sunlight around the Moon will be visible. This is why this type of eclipse is called a ‘ring of fire’ eclipse.
“If we miss this opportunity, in India, we have to wait for about 28 months for the next solar eclipse,” said Aniket Sule, chairperson of the Public Outreach & Education Committee of the Astronomical Society of India. “The next solar eclipse, which will be a partial solar eclipse, visible from India will take place on October 25, 2022. It would be visible in the western part of India.”
Also read: The Simple Physics of the Annular Solar Eclipse
The Sun is a very bright object, and looking at it directly can severely damage the eye and vision. There are special goggles made for looking at the Sun. These goggles filter the sunlight for safe viewing.
“Often the Public Outreach and Education Committee of Astronomical Society of India and other astronomical institutions and planetariums and other science popularisation agencies usually make arrangements for safe viewing of the eclipse,” Arvind Paranjpye, director of the Nehru Planetarium in Mumbai. “However, due to the lockdown this time, we are not able to make solar filters available. We strongly advise people not to gather in large numbers to view the eclipse given the pandemic situation. There are easy tips for viewing the eclipse from the safety of your home.”
Allaying rumours that the eclipse will mark the end of the coronavirus pandemic, Sule said, “A solar eclipse is caused when the Moon comes in front of the Sun for a short time. As seen from Earth, eclipses occur somewhere [over Earth’s surface] two to five times a year. Eclipses don’t impact microorganisms on Earth. Likewise, there no danger in eating or stepping out during an eclipse. No mysterious rays come [from] the Sun during an eclipse.”
Tips for viewing the eclipse
Do not use sunglasses, goggles, exposed X-ray sheets or lampblack over glass. They are not safe – nor is viewing the Sun’s image on the surface of water.
The Sun can be seen through welders’ glass #13 or #14.
Make a pinhole in a card sheet and hold it under the Sun. At some distance, place a screen of white paper. The image of the Sun can be seen on this sheet. By adjusting the gap between the sheet and the screen, the image can be made larger.
Look at the shadow of a bush or a tree. With the gaps between the leaves acting like a pinhole, numerous images of the eclipsed Sun can be seen on the ground.
You can use a strainer for making pinhole images.
Cover a compact makeup kit mirror with black paper, with a small hole at the centre. Reflect the image of the Sun on a distant wall in shadow. You can get a projected image of the eclipsed Sun.
Eclipse timings and sites
Bhuj will be the first town in India to see the beginning of the eclipse, at 9:58 am. The eclipse will end four hours later, over Dibrugarh, Assam, at 2:29 pm.
Ghersana, at the western boundary of India, will be the first to witness the annular phase of the eclipse at 11:50 am. It will last for 30 seconds.
The Kalanka peak in Uttarakhand will be the last major landmark from which to observe the annular eclipse, at 12:10 pm for 28 seconds.
T.V. Venkateswaran writes for India Science Wire and tweets at @TVVen.