June 21 annular solar eclipse: All you need to know

The solar eclipse occurring on June 21, 2020, is not only the last one this year, but is also going to very special. During the eclipse, the Sun will appear as a ‘ring of fire’ for a brief moment, dazzling all those who are fortunate to view this cosmic show.

Can I see it from my place?

The enchanting ‘ring of fire’ will be visible from parts of north India. Specifically, a narrow band, called the path of annularity, will pass through Anupgarh, Sri Vijaynagar, Suratgarh, Ellenabad, Sirsa, Ratia, Jakhal, Pehowa, Kurukshetra, Ladwa, Yamunanagar, Jagadhri, Behat Dehradun, Chamba, Tehri, Agastmuni, Chamoli Gopeshwar, Pipalkoti, Tapowan and Joshimath.

But people in the rest of India need not despair; a partial eclipse will be visible from everywhere in the country.

The eclipse will commence when the disc of the Moon begins to cover the face of the Sun. The annular phase of the eclipse will be first seen over Ghersana at the western boundary of India at 11:50 am. At this location, the first contact, sparśa, will commence around 10:12 am and the fourth contact, mokṣa, which is the ending of the eclipse, will take place around 1:36 pm.

The maximum eclipse, madyakāla or parvānta, which is the maximum obstruction of the Sun, will be around 11:50 am. Bhuj will be the first town in India to see the beginning of the eclipse 9:58 am. The eclipse will end four hours later at Dibrugarh at 2:29 pm. From place to place, the timings will differ by few seconds.

If you happen to watch the eclipse at this time from anywhere in the path annularity, the Sun would appear as a dazzling ring of fire.

Eclipse, a cosmic shadow play

A wayside tree obstructs the rays of the Sun and cast a shadow on the ground. In like manner, at times the Moon comes in between the Earth and the Sun, and obstructs the view of the Sun partially. If the alignment is perfect, we have a total solar eclipse. In the same way, the Moon may enter the shadow of the Earth, resulting in a lunar eclipse.

The total solar eclipse and annular solar eclipses are possible only for a cosmic coincidence. The Sun is about 400 times bigger than the Moon and also 400 times far from the Earth. Hence, both appear almost of same size when seen from Earth. Thus, at times, the Moon can obstruct the Sun completely. Places on the surface of Earth, where the shadow of the Moon falls, experience solar eclipse. For the rest of the world, it would be like any other day.

What is annular eclipse?

The annular solar eclipse is a kind of total solar eclipse. The Sun, Moon and Earth are aligned in a straight line. However, on that day, the apparent size of the Moon is smaller than the apparent size of the Sun. When the obstruction is maximum, along the line of the annularity, only the central part of the Sun is obstructed. The circular edges of the Sun appear like a bright shining bangle.

How this curious heavenly drama occurs?

The path of the Earth around the Sun, and that of the Moon around the Earth, is elliptical. When the Earth goes around the elliptical path, at one point, usually around January 5, it is closest to the Sun, and at another place the farthest, generally around July 4.

When an object is near, it appears bigger and when faraway, appears smaller. When near, the Sun will look bigger and at far, a bit smaller. Similarly, the Moon passes through the two extreme points, closest and farthest, about once a month. It takes 27.55 days for the Moon to complete one revolution from the nearest location to the same position.

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If a total solar eclipse occurs when the Sun is relatively closer and the Moon afar, the apparent size of the Sun is bigger than the apparent size of the Moon. In that situation, the Moon will not be able to cover the full face of the Sun. While the central part is covered by the Moon, the edges of the Sun will stand out as a ‘ring of fire’. This is called an annular eclipse.

On June 21, 2020, the apparent diameter of the Sun will be around 1,890 arcseconds (0.525°) in visible diameter, 1.6 per cent smaller than average. However, on the day of the eclipse, the apparent diameter of the Moon will be around 1,875.6 arcseconds (0.521°). The apparent size of the Moon will be a bit smaller than the Sun. Hence, we will have the annular solar eclipse.

The difference in the diameters will be minimal. Therefore, the duration of the annularity, the period during which the Sun will appear like a ring of fire, will be only around 40 to 80 seconds. (One degree has 60 arc minutes and each arc minute has 60 arc seconds).

Will solar eclipse 2020 mark the end of coronavirus?

No. Eclipse is an apparent phenomenon, and no mysterious rays emanate from the Sun on the day of eclipse. Just like an umbrella temporarily obstructs the Sun and provide shade, the Moon’s shadow obstructs the view of the Sun. Therefore, it is not an event occurring in the Sun or a phenomenon that affects it.

Two to five solar eclipses occur every year, and the eclipse does not impact the microorganism on the Earth.

There is also no harm in eating and going out during the eclipse. Despite fake claims being circulated on social media, various studies have shown that cooked food does not get spoiled, nor going out and watching the eclipse is harmful. It is a natural celestial show, and to fear them is not human.

Then, what about Rahu and Ketu?

The cultural psyche in India is deeply permeated with the mythology of Rahu and Ketu. Nevertheless, ancient Indian astronomers such as Aryabhata and Lallacharya scoffed at the idea of a heavenly demon devouring the Sun and the Moon as being the cause of the eclipses.

Āryabhaṭīyaṃ, a renowned treatise written by Aryabhata around 1,500 years ago, clearly states that the shadow of the Moon falling on a location results in a solar eclipse and when the Moon enters the Earth’s shadow lunar eclipses takes place.

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Lallacharya, in his work Sishyadhivruddhida tantra, a handbook for students of astronomy, written 1,300 years ago, unambiguously rejects the Rahu-Ketu myths and Puranic claims. If the Sun is swallowed by Rahu (or ketu), then it should be invisible for everyone around the globe. Lallacharya says the falseness of the Puranic myth can be readily seen as on the day of the eclipse, the Sun is visible in its full glory outside of the eclipse path.

For example, at 11:50 am on June 21, for a person at Dehradun, 95 per cent of the Sun will be covered by the Moon at the very same time, only about 30 per cent of the Sun will be obstructed for a person at Chennai.

Faith in the myths is, in fact, an affront to the scientific heritage of Indian culture rooted in the rational and logical works of Aryabhata and Lallacharya.

How to safely watch the eclipse?

Any bright object is a threat to our eyes. Staring at bright light may cause harm from temporary discomfort to permanent retinal damage. That is why welders’ glass are donned, and it is advised not to look at a flash of lightning. Eclipse or otherwise, staring at the bright Sun is risky.

Do not use goggles, exposed x-ray films or smoked glass. They are not safe enough. One can use a solar filter made explicitly for watching the eclipse or project the image of the Sun using a telescope or pinhole camera. Usually, astronomical institutions, planetariums, science centres may be making special arrangements for making solar filters available to the public.

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Still, it might not be possible to do so during the lockdown period. The Public Outreach and Education Committee (POEC) of the Astronomical Society of India suggests following tips for viewing the eclipse:

• If you can lay your hands on welder’s glass #13 or #14, you can safely watch the Sun.
• Make a pinhole in a card sheet and hold it under the Sun. Fix a white paper on the ground for the screen. The size and the clarity of the image can be increased or decreased by adjusting the gap between the screen and the pinhole.
• You can observe the shadow cast by a tree during an eclipse. Small gaps between the leaves act like pinholes.
• One can use a fine mesh strainer, also known as sift. The sieves act like pinholes and create multiple beautiful images of the Sun. If you cover a colander with black paper and leave only one hole uncovered, you will have an excellent pinhole projector.
• Using the ‘compact’ makeup kit mirror, you can make your own sun projector as well. Cover the face of the mirror with black paper with a small hole on it. One can then reflect the Sun’s image on a distant wall.

(The author is a science communicator with Vigyan Prasar)