Reason for apparent retrograde motion in Indian astronomical texts

[Nityanand Misra]

Dear list members

Does any Indian astronomical texts explain the reason (as was understood then) behind apparent retrograde motion (वक्रगति) of planets? The Greeks (Apollonius, Hipparchus, and Ptolemy) used epicycles to explain the retrograde motion, did we have something similar?

Please note that I am not looking for the astrological implications of retrograde motion (वक्रगति) but the astronomical model Indians had (if any) to explain it.

Thanks, Nityananda

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Nityānanda Miśra

[Nilesh Oak]

Dear Nityananda ji

A possible tangent (so be aware)

Mahabharata text uses the word 'vakra' however it appears (based on my 20+ years of work) that MBH does not refer to the phenomenon in the sense of 'retrograde'  at all but rather oblique crossing of the planet across the ecliptic (at the points of nodes - node of that specific planet - i.e. the intersections of its orbit and the ecliptic).

On the other hand, the 'retrograde' motions themselves are defined in various ways. e.g. (1) In case of saturn/Jupiter  as "the planets became stationary around a certain nakshatras space, while shining brightly (as are expected during retrograde)  (2) Mars - becoming steady, traveling in non-normal direction (backwards) and shining brightly (as is expected during retrograde)  (3) Venus - Making a parikrama (forming a loop) near a certain nakshatra.

Warm regards,

Nilesh Oak

[Anand Hudli]

Dear Scholars,

Two corrections, due to मन्दोच्च and शीघ्रोच्च, are applied to arrive at the true celestial longitude of a planet. It  was recognized that a planet slows down as it approaches a point called मन्दोच्च (apogee) and that a planet speeds up as it approaches a point called शीघ्रोच्च, a point where the planet is on the other side of the Sun or in conjunction with the Sun. The सूर्यसिद्धन्त, in the second chapter, explains retrograde motion, वक्रगति as being effected by two divinities stationed at मन्दोच्च and शीघ्रोच्च, who pull the planet backward and forward. However, it was also recognized that as a planet's motion turns retrograde once its celestial longitude has considerably increased with respect to its conjunction point. In fact, the सूर्यसिद्धन्त mentions the start of retrograde motion when this difference in longitude, called शीघ्रकेन्द्र, is 144 degrees for Budha (Mercury), 163 degrees for Shukra (Venus), 164 degrees for Kuja (Mars), etc. 

It appears that the Aryabhatiya has settled for an epicycle based explanation, rather than that of divine beings pulling a planet. 

Anand

[Subrahmanyam Korada]

नमो विद्वद्भ्यः

Although it is difficult to provide any textual reference we are taught that sometimes  a planet picks

up a higher pace and after some time travels in reverse gear (वक्रगतिः) to maintain the specific distance from

the Sun .

धन्यो’स्मि

Dr.Korada Subrahmanyam
Professor of Sanskrit, CALTS,
University of Hyderabad,
Ph:09866110741(M),91-40-23010741(R),040-23133660(O)

Skype Id: Subrahmanyam Korada

Blog: Koradeeyam.blogspot.in 

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[Bijoy Misra]

Dear Prof Korada,

Would not that be a pure illusion from the ground?

Since only relative distances between luminous objects

in the spherical sky dome is measured, there is no distance 

factor.. Am I missing something?

Bijoy Misra

[Anand Hudli]

Dear Scholars,

One may cite the first few verses from the second chapter of  सूर्यसिद्धन्त and 2.51 as found below:

https://archive.org/stream/SuryaSiddhanta_201311/Surya-siddhanta#page/n101

https://archive.org/stream/SuryaSiddhanta_201311/Surya-siddhanta#page/n181

Anand

[Anand Hudli]

On Thursday, September 27, 2018 at 8:08:41 AM UTC+5:30, Anand Hudli wrote:

Dear Scholars,

One may cite the first few verses from the second chapter of  सूर्यसिद्धन्त and 2.51 as found below:

https://archive.org/stream/SuryaSiddhanta_201311/Surya-siddhanta#page/n101

https://archive.org/stream/SuryaSiddhanta_201311/Surya-siddhanta#page/n181

Correction: 2.51 should be 2.52.

[Ramaratnam S.]

I raised a point regarding the Bodhayana amavasya. On reflecting for a while I thought of a possible answer myself. The tarpana is to be performed during the day between 11 a.m. and 12 noon. There is no question about it. But on which day? The answer is - on the day when the amavasya tithi is present sometime during the day time ( at least in the evening) and also in the night. After all amavasya is concerned with night. This is the concept behind Bodhayana amavasya and Bodhayana is correct. On the other amavasya day succeeding the bodhayana amavasya, there is amavasya tithi during the tarpana time (and therefore, this is also correct and justified) but not in the night. It will expire by evening itself.

Ramaratnam

[Nagaraj Paturi]

Sir, can you please post your responses in the relevant thread, so that your valuable answers can be quickly and conveniently located at a later time through the group's search interface ? 

Nagaraj Paturi

 

Hyderabad, Telangana, INDIA.

Director, Indic Academy of Sanskrit and Indological Studies.

BoS, MIT School of Vedic Sciences, Pune, Maharashtra

BoS, Chinmaya Vishwavidyapeeth, Veliyanad, Kerala

Former Senior Professor of Cultural Studies

 

FLAME School of Communication and FLAME School of  Liberal Education,

 

(Pune, Maharashtra, INDIA )

 

 

 

[Dipak Bhattacharya]

27/9/18

Late Professor Vibhutibhushan Nyayacharya (1911-1988) of the Varanaseya Samskrita Visvavidyalaya had a paper on Kepler’s theory of planetary motion as viewed from the Indian astronomical and Navyanyaya point of view published around 1960 in the Our Heritage, Department of Post-Graduate Training and Research, Government Sans krit College, Calcutta. Professor Satyen Bose read it and gently questioned the applicability of Navyanyaya or Aristotlean logic in astronomy. Professor Gaurinath Sastri was present at the meeting. He asked if a logic became invalid because of its origin.

DB    

[Subrahmanyam Korada]

नमो विद्वद्भ्यः

Would not that be a pure illusion from the ground?

Since only relative distances between luminous objects

in the spherical sky dome is measured, there is no distance 

factor.. Am I missing something?

                                                                    ----- Vidvan Bijoy Misra

Please try to understand one thing - just like any other शास्त्र , ज्योतिषम् is also a शास्त्रम् , i e compiled by

sages / ऋषिs , who , with their capacity called योगिप्रत्यक्षम् ।

You are right when you said - pure illusion from the ground - because it is not possible to find with 

naked eyes .

If you believe in व्याकरणम् , योगानुशासनम् , आयुर्वेद etc. you  believe in ज्योतिषम् also.

It is not possible to check the शब्दs that are there in 1130 branches of Veda (all are not available) and the

vast secular literature - but Panini compiled a व्याकरणम् for both वैदिक and लौकिक शब्दs . How did he do

such a marvelous deed which is not possible with naked eyes . Today one may not have such a 

capacity but one cannot refuse to accept when others have exhibited the same some time ago  and

the proof is available today.  

There is सिद्धान्तस्कन्ध in ज्योतिषम् that deals with such aspects and one has to follow the procedure

prescribed therein .

Hari discusses this issue elaborately in  ब्रह्मकाण्ड of वाक्यपदीयम् ।

The tradition sustained very high level criticism that has been there since time immemorial and so many people cannot be blind for so long .

Hope this will clarify your doubt .