Vimshottari Dasha and 27/28 Nakshatras

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Lately I have been thinking about the Vimshottari dasha system of Jyotish and the reasoning for the order of the planets and how many years are allocated to each planet. In this post I will explain the basics of the system for the benefit of those who are not familiar with it and then lay out some observations about it. Any feedback or any additional information is welcomed.

I was actually going to post to another astrology forum, but I saw the post titled ?The 28 Ancient Nakshatras? on this forum while I was researching the post I am making now. I feel this post relates to that post because it ponders the ?27/28 nakshatras? question.

The Vimshottari dasha is a nakshatra dasha system meaning it is based on the nakshatra (lunar mansion) system of Jyotish. In the Vimshottari dasha system the nakshatras are currently 27 in number. I did some internet research given it is stated that the nakshatras were 28 in number at one time; also, some people still advocate a 28 nakshatra scheme. This immediately peaked my interest. If there were 28 nakshatras in number, then the Vimshottari dasha scheme as follows would not fit:

Ketu (7 years)
Venus (20 years)
Sun (6 years)
Moon (10 years)
Mars (7 years)
Rahu (18 years)
Jupiter (16 years)
Saturn (19 years)
Mercury (17 years)

Total years are 120. I wonder if the years equate with the 120 degrees of the span of the three iterations around the 27 nakshatras with each planet ruling three nakshatras.

I considered whether the years of the different dashas are tied to the unequal nakshatras some people advocate, but I did not see a correlation between Venus ruled nakshatras having a larger piece of the unequal nakshatras than Sun ruled unequal nakshatras.

One other observation I had was the quantity of the years of each planet.
Jupiter (16) + Mercury (17) + Rahu ( 18 ) + Saturn (19) + Venus (20) = 90

Sun (6) + Ketu (7) + Mars (7) + Moon (10) = 30

It is interesting how the high numbered year planets equal 90 and the low numbered year planets equal 30. 30 is 1/3 of 90.

As you can see there are 9 planets in the Vimshottari dasha system (Jyotish considers Rahu (North node) and Ketu (South node) as planets). Nine divided into twenty-seven is three meaning there are three iterations of the 9 planets being assigned to the 27 nakshatras. If it was 28, then the Vimshottari dasha scheme would not work. If we could determine when 27 nakshatras were used, then we could determine a rough time when the Vimoshottari dasha system might have been developed. After reading the ?28 Ancient Nakshatra? post, it seems it is not clear what nakshatra system came first.

One idea that popped into my head: Is there is a nakshatra dasha system that uses 28 nakshatras that is applicable to all charts and not a special dasha system? If we took out Rahu and Ketu from the current Vimshottari dasha system, then we could fit the seven visible planets into the 28 nakshatras and have four iterations of the seven visible planets. Maybe the whole idea of the 27 or 28 nakshatra idea revolves around the Rahu/Ketu matter, just like the Jaimini system with the karakas. There is one karaka system that includes Rahu and one that does not. Often in Jyotish, Rahu and Ketu will be used and sometimes they will not be used, even though they are given planetary status in Jyotish.

I wonder how people who advocate the 28 nakshatra position reconcile this with using the Vimshottari dasha, as nine planets (including Rahu and Ketu) do not fit into the 28 nakshatra system.
Michael Douglas Neely
Author of Life Cycles: Astrology and Its Connection to Nature

http://www.lulu.com/spotlight/MichaelDouglasNeely
https://independent.academia.edu/MichaelNeely

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Michael Douglas Neely wrote:
I wonder how people who advocate the 28 nakshatra position reconcile this with using the Vimshottari dasha, as nine planets (including Rahu and Ketu) do not fit into the 28 nakshatra system.
The ancient 28 nakshatras were individual stars or asterisms. The Vimshottari system is based on a 27-fold equal division of the ecliptic, or 27 lunar mansions. The ancient nakshatra stars only roughly align with the newer system of mansions.

If astrologers wish to retain the 28 nakshatra stars and asterisms, then they have to be correctly placed within the 27 mansions as individual points or asterism spans. Then based on historical data, individual interpretations can be given to the ancient nakshatra areas. In contemporary times modern authors have mis-alinged the ancient nakshatra deities with various mansions. As far as I know, no one has really dealt with that contradiction in actual astrological work. The majority of ancient nakshatra stars and asterisms do fall within the correct 27-fold mansion divisions, but several do not.

India has never had a system of 28 equal lunar mansions. The equal 28-fold division is an Arabic invention, and has no relationship to the Vimshottari system.
http://www.snowcrest.net/sunrise/LostZodiac.htm