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From Wiki:
"Trepidation (from Lat. trepidus, "trepidatious"), in now-obsolete medieval theories of astronomy, refers to hypothetical oscillation in the precession of the equinoxes. The theory was popular from the 9th to the 16th centuries.

The origin of the theory of trepidation comes from the Small Commentary to the Handy Tables written by Theon of Alexandria in the 4th century CE. In precession, the equinoxes appear to move slowly through the ecliptic, completing a revolution in approximately 25,800 years (according to modern astronomers).

Theon states that certain (unnamed) ancient astrologers believed that the precession, rather than being a steady unending motion, instead reverses direction every 640 years.[1] The equinoxes, in this theory, move through the ecliptic at the rate of 1 degree in 80 years over a span of 8 degrees, after which they suddenly reverse direction and travel back over the same 8 degrees. Theon describes but did not endorse this theory."
AJ wrote on Skyscript on 30 May 2019:
The author [Vinay Jha] advocates a "scientific" approach to astrology yet uses an ayanamsa that is clearly "non-scientific" the so-called Siddh??ntic Ayan??msha that is a modern rehash of the ancient oscillating precessional view held by some in ancient times.

http://skyscript.co.uk/forums/viewtopic.php?t=10531
http://www.snowcrest.net/sunrise/LostZodiac.htm

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Anyone who gets their Indian cosmological understanding of Trepidation, or anything to do with ancient cosmology, from Wikipedia deserves to believe what they are reading.

Of course modern physical astronomy rejects the idea of Trepidation. It also rejects, well... all of astrology, be it tropical, sidereal, the idea of the zodiac, the influence of planets onto human affairs, it rejects the idea of an Ascendant having anything to do with your life. It knows for one, that the poor folks born above the polar circle can have an ascendant that is several months old.
I know modern astrologers want to be vindicated by science. This will be a wild goose chase as long as science is a purely material pursuit.

There was in siddhantic times the notion of 2 movements of the ayanas. To quote V J : ' precession was known to ancients, but this precession was Trepidation of Bhachakra (=Dol??yana) as mentioned in all siddhantas and Narada Pur??na, and not the modern concept of Chakr??yana (circular motion of equinoxes or solstices). But the latter was also known to ancients, as shown in the section on Bhaskara-ii above.'

These ideas of dolayana and chakrayana are not for the casual observer. They are found in the motions of Veethees described in several Puranas,which are calculated from Divine (Divya) Equinoxes and Solstices, themselves siddhantic and puranic concepts, based on Dolayana (meaning of trepidation) idea from Siddhantas and Puranas. In Puranas for ex. the equinoxes and solsices are always 3 nakshatras removed from the vernal point or tropical solstices. This obviously supports Trepidation, and not a modern precession theory. The ayanamsa motion is more involved than mere precession of the equinox.

I have written an article on these, as well as the trepidation ayanamsa from Surya Siddhanta, on my site. And readers are refered to the VJ article.


http://vedicastrology.wikidot.com/ayana ... ssion#toc4

My article on the ayanamsa in english
https://pjtou.github.io/ayanamsa.html

An article on solstices and equinoxes, in french for now.
https://pjtou.github.io/SolsticesJyotish.pdf.html

These notions are not exclusive to Vinay Jha, and many traditional astrologers base their charts on siddhantic principles, like Bimala Prasada Siddhanta Saaraswati did (the Guru of A.C. Bhaktivedanta, founder of the Hare Krishna movement). He actually did translate the Surya Siddhanta and S Siromani, and advocated their use for astrology. He was the most famous astronomer and astrologer in the late 19th century. But this will be too much work for most people.

Re: On the Original Ayanamsa

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Hello Pierre: Just curious... Does the SS explain or account for the precession of the perihelion of Mercury?
Cheers.[/quote]

Hello
SS computes a distinct cosmological model for all grahas, not planets. This local universe is much smaller than the physical one. For mercury and venus there is a specific procedure and orbits. As far as i understand precession is for all grahas. It is not precession of the equinox although they were aware of it on the physical plane.

Re: On the Original Ayanamsa

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Pierre Touchard wrote:Hello Pierre: Just curious... Does the SS explain or account for the precession of the perihelion of Mercury?
Cheers.
Pierre Touchard wrote: SS computes a distinct cosmological model for all grahas, not planets. This local universe is much smaller than the physical one. For mercury and venus there is a specific procedure and orbits. As far as i understand precession is for all grahas. It is not precession of the equinox although they were aware of it on the physical plane.
Check my understanding of what you said here Pierre... According to SS there are the "physical" planets, then there are "Grahas" that are not necessarily at the same point as the "physical" planet because the local universe is smaller?
So the observed postion of a planet would be different than where its partnered Graha really is according to SS.

Re: On the Original Ayanamsa

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Check my understanding of what you said here Pierre... According to SS there are the "physical" planets, then there are "Grahas" that are not necessarily at the same point as the "physical" planet because the local universe is smaller?
So the observed postion of a planet would be different than where its partnered Graha really is according to SS.[/quote]

Correct, Grahas are not exactly at the same point as seen from the earth as planets are.
The local universe, I mean here the divya planets (Grahas) of the solar system, are smaller in size and form closer orbits than the physical planets, which led astronomers to believe the ancients were mistaken.

But Puranas and ancient Siddhantas were concerned with religious and astrological Grahas, not physical planets. Some people think that the SS also had a physical model for planets, that was discarded because astrology was their main interest. But those people dont speak much. So it is very difficult to get an education about the whole topic and now astrologers only stick to the physical model and believe it is the only reality.

Re: On the Original Ayanamsa

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Check my understanding of what you said here Pierre... According to SS there are the "physical" planets, then there are "Grahas" that are not necessarily at the same point as the "physical" planet because the local universe is smaller?
So the observed postion of a planet would be different than where its partnered Graha really is according to SS.
Pierre Touchard wrote:Correct, Grahas are not exactly at the same point as seen from the earth as planets are.
The local universe, I mean here the divya planets (Grahas) of the solar system, are smaller in size and form closer orbits than the physical planets, which led astronomers to believe the ancients were mistaken.

But Puranas and ancient Siddhantas were concerned with religious and astrological Grahas, not physical planets. Some people think that the SS also had a physical model for planets, that was discarded because astrology was their main interest. But those people dont speak much. So it is very difficult to get an education about the whole topic and now astrologers only stick to the physical model and believe it is the only reality.
Thanks for clarifying.
Cheers.