When did the head of the ṛtus and saṃvatsara separate?

We find many different narratives of Season’s beginning or season’s head in Indian narratives, in different Indic texts and usually this brings us an understanding that new year also began from these points.

Especially it gets divided into two kinds, one Madhu Mādhava months and another Tapas Tapasya months as the season’s beginning. In the past few blogs we understood fairly that Madhu-Mādhava months mostly occurs only in Vedas, Brāhmaṇas. And Tapas-Tapasya in Saidhāntic, Purāṇas and other later texts.

This creates an ambiguity on finding from where the saṃvatsara began. I tried to address this problem in one of my blogs (see here), where I showed that though season’s beginning found from Tapas, Tapasya but Saṃvatsara began from Vasanta-Viśuva, i.e., vernal equinox only. But it appears we should go deeper and try to chaff out the time when this could have had happened, and why and how…

ṛtus and saṃvatsara

We already saw that Vasanta-Viśuva (see here) used to be the new year beginning in the Vedas and Brāhmaṇas. We also saw that this is prevalent in Sūryasidddhānta also with the help of Mānādhyāya 9th & 10th verses. It clearly says that ṛtus are śiśirādayaḥ but vatsara from meṣādayaḥ.

भानोर् मकरसङ्क्रान्तेः षण्मासा उत्तरायणम् ।
कर्क्यादेस् तु तथैव स्यात् षण्मासा दक्षिणायनम् ॥९॥

द्विराशिनाथ ऋतवस् ततो अपि शिशिरादयः ।
मेषादयो द्वादशैते मासास् तैर् एव वत्सरः ॥१०॥

From the sun’s entrance in Capricorn six months are his sun’s progress, So likewise, from the beginning of Cancer, six months are his southern progress..9.

Thence also recorded the Seasons, the cool seasons and the rest, each prevailing through two signs. These twelve, commencing with the Aries, are the months; of them is made up the year.
Sun’s rising points on globe and shift of Indian names of tropes

Let us image how this information of 9th & 10th verse from Sūryasiddhānta looks on the globe. Meṣa saṅkrānti, i.e., Sun in Meṣa should be commencing the solar month on equator on Vernal equinox day and Karka saṅkrānti, i.e., Sun’s enter in Karka should coincide with 21st June, i.e., summer solstice day.

The above diagram shows the condition of todays time. Now a days Karka saṅkrānti occurs on 16th of July and Sun takes trope from Tropic when it is in Mithuna rāśī. The saṅkrānti of Mithuna occurs on 15th June and it’s saṅkrānti saṃkramaṇa is still 5-6 days away from 21st June. Since the rate of the shift of precession of equinoxes is 1 day every 71 years. Then say after around 426 years Mithuna saṅkrānti will coincide with the Sun’s trope. This would mean that we can change the name of Tropics of Cancer to Tropics of Gemini, even today we can say so. But when it coincides with the solstice point, that day rainy season can be assumed to be starting from Gemini- Mithuna. This is how the solar month rāśī name w.r.t season’s change. Hope this is clear.

Now lets understand the solstitial colure and the arc of Solstices by gnomon.

Arc – Shadow path of solstices, straight line shadow path E-W axis on equinoxes

Fig.1: Diagram in perspective showing the north south (meridian) line and the three declination lines typical of simple sundials. The vertical gnomon corresponds to an observer placed on the equator. It will cast shadows on the floor along curves that fit inside the two extreme ones depicted in this figure. The straight middle line corresponds to the shadow’s path during equinoxes. The curved line to the left corresponds to the shadow’s path during the June 21 solstice.

It is easy to visualize the shadow exceeding after the equinox day from the straight line however the shadow remains on the arc path for some days on solstice days as sun appears still during solstices and its difficult to find the exact day of solstice since the sun remains in the respective hemisphere. How did our ancients understand and sorted the problem of observing the exact date of solstices.

Imaginary solstitial colure comes to our rescue.

An imaginary solstitial colure, krānti vṛta and ayana vṛta comes to our rescue to explicitly decide where to keep the solstice cardinal points, and after how many days of equinoxes will the solstices occur. And this solstitial colure was introduced by Sūryasidddhānta or Saiddhāntic people which is dealt and shown in the armillary section. This was more effective than the nāḍī (water) yantra, Gnomon-sundial which could go astray due to any reasons (cloudy days or malfunctioning of water vessel as well as difficulty of locating certain stars at solstice points). This was also effective to locate all the asterisms at celestial latitudes and longitudes and place certain stars according to its declination, thus astronomy became more calculation based. We have seen from the paper* of Anil Narayanan et al that latitudinal corrections were last done during 7300~7800 BCE. This is a proof that observational astronomy was converting into calculation based astronomy.

The above is the image of armillary which gives new definition to vedic udagayana and dakṣiṇeti, i.e., VE to AE and AE to VE as krāntivṛta or krāntimaṇḍala, i.e., ecliptic. The ādhāra ayanavṛtta’s intersection with krāntivṛtta gives C, and C1 as solstice points. Udaya lagna and Asta lagna are the rising sun defines latitude from where the observation takes place. This way the experiential seasons got their mouth perfected with the solstices. Longer stay of sun’s shadow during solstices could now easily determine the date of solstices giving birth to Tapas-Tapasya as season’s beginning from beginning of a cardinal point. Therefore, makarādi, śiśirādi were ṛtavaḥ.

However, the saṃvatsara began from Meṣa only which was at the equinoctial point just like the vedic year stated in Brāhmaṇas.

द्विराशिनाथ ऋतवस् ततो अपि शिशिरादयः ।
मेषादयो द्वादशैते मासास् तैर् एव वत्सरः ॥१०॥

But when in the past this would had become obvious to observe Tapas-Tapasya instead of peak of vasanta between Madhu and Mādhava. We see the updates during ranging from 500 CE…5200 BCE, 7300~7800 BCE, 12000 BCE (two pole star-Vega and Canopus and aphelion-manda opposite in the winters). We now have only two of one evidence that goes back to -27 deg from Aries from a controversial verse in Sūryasiddhānta. Until it was experienced it would not have found place in the verse in context and this was happening during Vernal at the junction of U. Bhādrapada and P. Bhādrapada~ around 23500 BCE.


  1. Uttarāyaṇa and Dakṣiṇayana were not year beginnings even in Saidhāntic texts but were first discovered in Saidhāntic texts with finer definitions due to the armillary.
  2. Year began from Vernal Equinoctial point alone.
  3. Tapas-Tapasya months got their new designation as head of ṛtu and are found in later texts, and it appears to have come into existence possibly during 23500 BCE.
  4. Other many texts which says śiśirādi should be taken as ṛtu head but saṃvatsara should not be confused with the śiśirādi.
  5. Sūryasiddhānta clears the speculation of saṃvatsara, i.e., the year beginning.



Meṣa saṅkrānti- Sun in Aries

Karka saṅkrānti- Sun in Cancer

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