A Rare Hybrid Solar Eclipse on 20Apr23

(Invisible in India)

 

If you're outside the path of totality of eclipse, if there's any way you can get into the path of totality for the eclipse, do it. Take the day off. Take the kids out of school. This is a once-in-a-lifetime opportunity for most people to see a total eclipse, and it is one of the grandest sights in all of nature. It's something you'll always remember, and you'll pass stories of it onto your grandchildren.

- Fred Espenak

Alas! The exhortations of Fred Espenak, the great eclipse chaser and inveterate ‘computer’ of eclipses for NASA, will have to be ignored by everyone in India, and indeed in most parts of the world, because the entire path, let alone the much narrower and crucial path of totality, of this rare hybrid solar eclipse bypasses most inhabited lands on the globe.  However, the really significant part of its progression can be followed live on Thursday, 20th April 2023 from 08:00 AM to 11:30 AM (approx times), with the maximum occurring around 09:45 AM, on several online channels, including: https://www.timeanddate.com/live/eclipse-solar-2023-april-20 .

Solar Eclipses

First, let me review what solar eclipses are. The following text is adapted from one of my earliest blog articles on eclipses [see 02) Total Solar Eclipse of 1980 (Feb 10) ]: 

Eclipses of the Sun and the Moon as viewed from any place on Earth are possible only because of a fortuitous and accidental circumstance associated with the Sun and the Moon. While the Sun is about four hundred times bigger than the Moon, it is also nearly as many times farther away from the Earth as is the Moon. Therefore, they appear to be of nearly the same apparent size (about 0.5 degree in angular diameter) as seen from the Earth. On the occasions when these three bodies are nearly in a line, solar or lunar eclipses, which may be partial or total, are possible. A partial solar eclipse results when the lunar disk hides only a portion of the solar disk on a new moon day. A total solar eclipse happens when the lunar disk is slightly larger than the solar disk and blots it out of sight from the earth at the viewing site, revealing the spectacular sight of the solar corona, which can be viewed with the naked eye. An Annular Eclipse results if the lunar disk is slightly smaller than the solar disk and a thin peripheral ring of the Sun can still be seen at maximum eclipse. 

Total and annular solar eclipses are extremely rare events at any specific place on earth and last only a few minutes at most.  For the duration of a total solar eclipse, day turns nearly into night and produces some breathtakingly beautiful effects, justifying Fred Espenak’s exhortations cited above.

With reference to the diagram below, total and annular eclipses are possible at locations in the umbral and antumbral shadow regions, and partial ones outside of them, in the penumbral shadow regions.

[From nineplanets.org]

 

Hybrid Solar Eclipse

    Now, to the question of what are hybrid solar eclipses.   These are exceptionally rare and rather strange phenomena in which the eclipse can alternate between a total one and an annular one, or vice versa, as the lunar shadow sweeps over the earth, because of changes in the Sun-Moon-Earth positions by just the right amount in the right manner.  As a result, it may be possible for an observer to see an annular eclipse followed by a total one, or vice versa, a little later or earlier, depending upon the geographical location.  It would also be possible for one observer to see one type and another the other type at a different location.

Hybrid Eclipse of 20Apr23

The current hybrid solar eclipse will occur in the southern hemisphere, well away from the Indian subcontinent. It will transition from annular to total and back again to annular at two specific points along the path, at remote locations in the seas. The following map shows the path of the eclipse with its outer limits, and the very thin path of totality within. The event will be observable as a total solar eclipse from Exmouth Peninsula in Western Australia (up to 1 minute), Timor Leste (74 seconds) and West Papua (69 seconds), all sparsely populated regions.  The inset gives an expanded view.

Reproduced from xjubier.free. Fr

This hybrid solar eclipse takes the name Ningaloo Eclipse, derived from an aboriginal modern-day term that refers to the Cape Range National Park and surrounding areas in the northern tip of Western Australia, best located for viewing the eclipse. 

For us in India the event is noteworthy only for its unusual nature, occurring in faraway places, and mostly over the sea. Yet, the ubiquitous soothsayers will be quick to establish every conceivable link between it and human affairs as usual, as predictably as the event itself!

The last such hybrid eclipse occurred in 2013, and the next one is slated to occur in 2031.  Thereafter, it is a long wait until 2164!