Fwd: Saptarshi

hinducivilization , " adhin88 " <adhin88 wrote:

extract from:

www.aip.de/~aniket/Saptarshi%20paper.pdf

Saptarshi's visit to different Nakshatras:

Subtle effect of Earth's precession1

Aniket Sule1, Mayank Vahia2 , Hrishikesh Joglekar3, Sudha Bhujle4

Summary

In several ancient Indian texts a mention is made of the movement of

the Saptarshi constellation (Big Bear or Big Dipper) in the sky,

visiting each nakshatras for 100 years.

Saptarshi is said to visit a nakshatra if the nakshatra is in the

middle of the stars in the first part of Saptarshi. Since

astronomical objects except planets are more or less stationary in

the sky, this is generally considered a fanciful statement devoid of

astronomical meaning.

We show that this may not be so. We show that the visit of Saptarshi

to different nakshatras may be a very significant astronomical

observation. The transition is not a constant of time since it

depends on the proximity of the Saptarshi to the North Pole, which

changes due to Earth's precession and relative sizes of different

nakshatras. We show that since 8000 BC, Saptarshi has visited 5

different nakshatras and for one of them, the transition happening in

the span of roughly 100 years. We show that this interpretation

allows dating of this belief which is consistent with other evidences

of the Harappan civilisation and date different Saptarshi Era with

calendar dates.

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Conclusions

The Saptarshi pointer has very practical significance in naked eye

observations.

Saptarshi being brightest constellation in the sky, it was obviously

used for timekeeping during the night. The concept of the pointer was

to make sure that in case the view of Saptarshi was obstructed, there

should be another constellation which was synchronised with the

Saptarshi at their respective highest positions in the sky. This

shows neat methodical structure of observations. During most of the

neolithic period (8000 – 3500 BC), this task was very easy as

Saptrashi were sychronised with Punarvasu which comprises of two

bright stars both of which are brighter than any one star of the

Saptarshi.

In due course of time, it must have been noticed that earlier

calibration of the Saptarshi and the Punarvasu was no longer true.

Probably, to maintain the simplicity, the slight

differences in the synchronisations of the Punarvasu and the

Saptarshi were ignored. But observers could no longer ignore it when

the Saptarshi were nearly in synchronisation with

the next nakshatra. As a consecuence, attempts were made to gauge

rate of rotation of nakshatras w.r.t. the Saptarshi.

The nakshatra next to the Punarvasu is Pushya which is a very small

nakshatra. As the geometrical concepts like angles etc. were probably

not developed at that time, rotation was measured simply in per

nakshatra basis. The simulations above show that indeed Saptarshi

spanned Pushya in roughly 100 years. Thus, very initial attempts to

determine rate of rotation of the Saptarshi coincided with 100 year

transition for a nakshatra. This puts a strong case that the mention

of the Saptarshi transition was a real astronomical observation and

not a random fanciful statement. The conventional interpretation of

the pointer would mean that this observation was done in around 2200 –

2100 BC. As this period matches well with the conventional knowledge

of the Saptarshi motion, we believe that the word nakshatra in the

reference referrs to the principle stars only.

The once only occurance of the 100 year Saptarshi transition was

probably noted by ancient observers, which generalised by later

generations due to misinterpretation. On the other hand it is also

possible that the observers who made the initial observation,

themselves hastily generalised it into a law. We propose as basic

need to gauge rotation rate of the Saptarshi won't be forgotten in

time span of few generations, the former is more

likely. Either way, the generalised law was completely wrong and was

of no astronomical significance.

The calenders using the concept of the Saptarshi era got popularity

in many parts of India as it had provision of naming different

centuries. Hence the later astronomers did not counter the law which

they realised to be untrue and let chronologists keep using the

Saptarshi calender. This explains why a calender based on

astronomical events was not used by astronomers and was relegated to

the domain of historians.

Same is the reason why no medivial astronomer mentions then position

of the Saptarshi pointer in his texts on astronomy.

This work also puts a limit on date of Vishnu Purana. As this was

only once in the known history event, we can say with reasonable

confidence that this shloka was drafted after 2000 BC. The second

line of shloka 106, mentions the Saptarshi being closer to Magha. A

cursory look at the table will show that this will further tighten

the limit to 1400 BC (by conventional interpretation). But the Magha

question requires detailed analysis and will be taken up in the

follow up paper.

At this point, we must note that the mention of the " rise of

Saptarshi " is a critical detail. At 2200 – 2100 BC era, the

declinations of a and b of Ursa Major were both 72o and 68o

respectivly. This means that their rise could only be observed

from the latitudes less than 18o. To this we can add some grace zone

of 2o – 3o to take into account imperfect conditions at horizon or

other small errors. This would mean that observer was located in

peninsular India below tropic of cancer which passes through Gujrat,

Madhya Pradesh, Jharkhand and West Bengal. For all the places north

of 24oN the first two stars of the Saptarshi would be circumpolar and

the question of rising won't arise.

In 2200 BC, Indus valley civilisation was in full flourish and was

the only dominent civilisation of the region. Many sites of Indus

valley civilisation, including bigger townships like Lothal, were

located south of tropic of cancer, where rising of the first two

stars of Saptarshi could be observed. We, thus, believe that the

observation of the Saptarshi motion was done by people from Indus

valley civilisation.

This is consistent with earlier work of Vahia (2005), which claimed

that the nakshatras themselves originated from Indus valley.

Alternate interpretation that the pointer is passing through centre

of the bowl would mean that the observation was done around 3200 –

3100 BC. At that time, the four stars had declinations of 67o, 65o,

70o and 74o respectivly, which means the observer should be

certainly below 25oN and most probably below 16oN which passes

through Goa and lower Andhra Pradesh. In 3200 BC, Indus valley

civilisation was probably just settling. Most

Indus valley sites are found in Indus – Saraswati basin and north of

Vindhyas. It is less likly that some systematic method of observation

would be in place in southern India.

Thus, we conclude that the centre of bowl interpretation is probably

not correct.

Thus, we conclude that, the observation of 100 year the Saptarshi

transition was done in 2200 – 2100 BC and most probably by Indus

valley civilisation. This piece of information got itself included in

the Aryan litreture at some later date. Over the generations the

original context of the observation was forgotton. It was used as

calendar and got mention in Puranas as an important astronomical

observation.

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