April 14, 2018

Why so many New Years? - Part 2 (De-mystifying Jyotish Siddhanta - Ganita)

Happy New Year once again!!! Today 14th April - is celebrated as Puthandu, Vishu, Baisakhi, Bohag Bihu and other names in many parts of India.

Having discussed the difference between the Jyotish (sidereal) and tropical (seasonal) calendars, the next question we look into is 'why are there different versions in this approach'? The ancient seers understood the impact the celestial bodies have on human mind and body. Out of the many such celestial bodies (Graha) - nine of them are considered most important (Nava-Graha). Out of these nine, the largest 2 that are visible to humans easily and govern daily routines are the Sun (Surya) and the Moon (Chandra).

Almost all Jyotish calendars that are in use, work with the movement of either the Sun (solar) or a combination of Sun and Moon (luni-solar). Surya represents the human self and governs the daily routines of the entire creation on earth. Chandra has a significant impact on water (as seen during tides) and in turn, the human mind. We have heard the word 'lunatic' :-) that is derived from the same root word of 'lunar'. New moon (Amavasya) or Full moon (Purnima) days are specially called out to be cautious.

As these calendars are not season based, we need to find a reference point in the space that we can use for defining the movements and start/ end points. This is the next foundation stone of Jyotish Siddhanta - the reference screen. Our universe is very interestingly designed and it turns out that most of the celestial systems in our galaxy are in a narrow plane. Given the relative movement of our solar system and the other star constellations in the vicinity, they give us a good 'almost static' reference screen in the background.


Astronomers in different cultures worldwide mostly narrowed down to 12 such star clusters that are more or less equally spaced out, and could serve as a reference. This helped divide the 360o reference screen into 12 parts. Even though the Earth revolved around the Sun, when you observe the Sun from Earth, you would see one of these reference clusters behind the Sun. These 12 clusters are now called Zodiac signs or Rashis. This is pictorially shown below (Image via Marcia Rieke)


This system allows you to reference locations of Surya and other Grahas on a celestial background. For simplicity, these 12 clusters are assumed to be equal in the radial time spread of 30o each. So, at any point in time, you can draw out the locations of all Grahas on this backdrop and that would become the Jyotish chart of that time.

Coming back to the calendar - the two primary versions that are in use are Solar and Luni-solar. In this list of Rashis, Aries (Mesha) is usually considered to be the start by Indian and Western astrologers alike.

The Solar calendar tell us that the new year would be when the Sun enters the Mesha rashi for the first time and that is today 14th April! This calendar would always have 12 months - one for each rashi as the Sun completes the 360o movement. This date would gradually shift by a day over a sixty year time period due to the difference between the Jyotish and Seasonal calendar.

The Luni-solar calendar calculates the month start on the next day of Amavasya. There are versions that use the next day of Purnima too - let us keep it aside for today. This tell us that the new year is on the next day after Amavasya (New moon), just before the Sun enters Mesha rashi - so that the Sun moves into Mesha rashi during this month. This new year was Gudi Padwa that we celebrated in the last post! The number of months would also vary between 12 and 13 - more on this later.

Hope this gives some insights into the different Jyotish calendars. More on this in the next post… till then, let us watch Surya along with the other Grahas transit through the 12 Rashis on this celestial stage.
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