Calendar Series Article 1 - Basic revolution

Before I start with the concept of basic revolution, I would like to make two statements.

1. Calendar anomalies can only be addressed after understanding the basic concepts.
2. We only need the mathematical, ganita, part of Jyotisha, and don’t need the predictive part, phalita, to address this.

The background of this article is linked to some panchanga makers who vouch only for tropical reference in their calendar. One such panchanga maker writes in his published public version as under:

“In Surya Sidhanta, a standard astronomical compilation, the year-length adopted is 365.25876 days which according to modern measurements should have been approximately 365.2422 days.”

I’ll simply call this statement ‘absurd’ that merely indicates that the editor is unaware of the concept of basic revolution. Let me explain it. My relevant books also have details about it.

I would be represented as DD (short form of my name) in the conversation below whereas a seeker would be on the other side.

DD:   Take a plain paper and draw a circle. Forget about sayana, nirayna (tropical/ sidereal) for the time being. Let us not even talk of any rashis. This is a simple reference circle. Tell me its size in terms of solar year length.

Seeker:
  365.2422 days (in line with his understanding of the concept as written above)

DD:   Ok, I take your size. The circle I have drawn has a size of 365.2422 days.

Now I place VE (Vernal Equinox) on this circle at a point (any random point), say A. Please tell me how precession is happening on this circle?

Seeker:
  A is moving westwards on this circle.

DD:   Okay. So, I am moving this point A backwards. Let it move to point B at a distance of 0.001 days (say). It means the length from A to B on the reference circle is 365.2422 minus 0.001 equaling 365.2412 days.

Seeker, are you not disturbing the tropical year length? It has been reduced from the specified modern length of 365.2422 days.

Does it not indicate that the size of the reference circle has to be more than 365.2422 days and shall be, in fact, 365.2422 days plus the precession, i.e. the sidereal/ nirayana size?

Seeker:
  No, it can’t be. How?

DD:   I'll explain. Let us now replace the reference circle size to the nirayana solar year length and place VE at A again and then move VE to B because of precession.

The length from A to B now is in line with the tropical.

Seeker:
  O, I know this.

DD:  If you know this, then how can the basic revolution be of the size of tropical year length?

The basic revolution circle is of the size of sidereal/ nirayana as only it is explaining how the tropical year is being formed.

And thus, your comparison of modern year length to the year length of the basic revolution specified in chapter 1 of the siddhanta is completely wrong. Why are you doing it?

Seeker:
  Because the revolution was supposed to be tropical and it is the siddhanta writers who mistakenly understood it as the sidereal. Refer to the manadhyaya chapter.

DD:   Please don’t read the book in reverse, from the last chapter. First grab the first chapter well, understand about the basic revolution and then proceed to the next chapter and so on. The basic revolution can’t be tropical as I have explained.

Remember, whether it is modern or ancient, astronomy is astronomy and the concept remains the same.

By the way, I have one more exercise that shall explain you the concept but I don’t want to overload you. First learn and try to understand the simple thing that I have explained here.

And please support removing the erroneous statement on Surya Siddhanta year length from any publishing.

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