Eclipses & Angular separation

A reader wrote…

“Dear Nilesh ji,

With reference to the Chapter 8- First day of the Mahabharata War in your book, consider the following:-

•Error Elimination- Experiment 28:- After running Voyager 4.5 simulation, you got the values for separation angles as 2.726 degrees and 0.127 degrees for the lunar eclipses of 30 September and 30 October during 5561 BCE.

•Was that the angle between (i) the line joining Sun and Earth upto the distance of the Moon and (ii) the centre of the Moon’s disk?

•In case of solar eclipse of 16 October 5561 BCE, the separation angle is given as 1.8 degrees. (Error Elimination- Experiment 30) In this case, since the Sun and Moon were close together, I assumed that this is the angle between their respective centres as seen from the Earth.

•Under this assumption and considering angular sizes of the Sun and the Moon as 0.5 degree each, I assert that the eclipse was not possible, since at a separation angle of 1.8 degrees, a solar eclipse would not be possible at all….!!!

However, the next couple of experiments appeared to contradict this assertion. Consider the following:-

•Experiment 32:- It mentions that Baily’s beads and solar corona were observed. Baily’s beads and corona can only be seen during total solar eclipse.
•Experiment 33:- It says the sky was covered with darkness. The Sun looks bigger during sunrise and sunset than that of its overhead position. Hence, if the eclipse is taking place when Sun is at high altitude in the sky, the probability of that eclipse being a total solar eclipse is more. This is because smaller disk of the Sun can easily be covered by the Moon.

If the separation angle is calculated by any other method, I request you to give the details.

Please give your inputs.”

My Response…

The experiment numbers (28, 32, 33, etc.) that reader refers to are from my book (When did the Mahabharata War happen)

Angular Separation

In layperson terms (or otherwise), simple way to descibe this angular separation is to think in terms of separation between the centers of sun and moon (as perceived from the earth) in case of solar eclipses, and separation between the centers of moon and earth’s shadow (as perceived from the earth0 in case of lunar eclipses.

Moon’s motion, angle and position are most challenging to predict and that is one reason why eclipse data becomes suspect as one goes back (or forward) in time, esepcially when one goes back thousands of years in antiquity (in this case about 7500 years). At this time, in antiquity, various other corrections (e.g. Delta time) come into the picture that affect our ability to predict eclipses (timing, type of eclipse, angular separation, location, etc.)

This is precisely the reason I included detailed measurements (as extracted using Voyager software) in my book. The hope is that those who are deep into the subject of eclipses will able to test, evaluate, improve and critique these observations and claims.

BTW, Mahabharata explicitly does not state first day of the War and thus we have to rely on stingy secondary data to make a conjecture for this first day of the War.

This reader wrote..

“•Under this assumption and considering angular sizes of the Sun and the Moon as 0.5 degree each, I assert that the eclipse was not possible, since at a separation angle of 1.8 degrees, a solar eclipse would not be possible at all….!!!”

This is correct.

So, naturally this reader wonders…he wrote…

“However, the next couple of experiments appeared to contradict this assertion. Consider the following:-

•Experiment 32:- It mentions that Baily’s beads and solar corona were observed. Baily’s beads and corona can only be seen during total solar eclipse.
•Experiment 33:- It says the sky was covered with darkness. The Sun looks bigger during sunrise and sunset than that of its overhead position. Hence, if the eclipse is taking place when Sun is at high altitude in the sky, the probability of that eclipse being a total solar eclipse is more. This is because smaller disk of the Sun can easily be covered by the Moon.”

My Response…

I wrote what I wrote (descriptions of Baily’s beads and corona) experiment 32 was originally mentioned by Dr. P V Vartak, in his ‘Swayambhu’

Mahabharata text refers to sun rising as if split in two and flames emanating from it. And thus wanted to capture that observation (for whatever it may be worth) for the benefit of future researchers; the same rationale why I specified angular separation measurements.

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2 thoughts on “Eclipses & Angular separation

  1. You are ridiculously smart. Seriously, I hope all is well with you, Nilesh. Your only slightly gifted friend, Dave

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