foreign so in the last video we got the basic idea of how the Indian calendar works it can be a lunar calendar or a solar calendar so now we will see a little more details of what constitutes a year because at the end of the day what is a calendar a calendar is a cyclical description of certain things which is called a year and within that you have the months and the days and so on so therefore let us understand how the Indian calendar has developed the notion of a year so The Vedic air consisted of 12 months each of 30 days and is called Savana in the you know the rigveda for example in the first mandala 164th sukta if you look at the 11th shloka it it depicts this as follows The Wheel of Time formed with 12 spokes revolves around the heavens without wearing out oh Agni on it or 720 Suns which is the days and the nights 360 days and 360 nights actually so actually according to this verse a year has 12 months and 360 days so this is the vedicure called Savana this is one notion of a year there are references to 12 lunar months known as vatsara amounting to 354 days but a year is made of 365.25 as we know now so this synchronization now there are 11 days cap 354 to 365. so the synchronization was done using the eka dasharatra ceremony to account for 365 days in a year leaving of course an error of 0.25 days at that time that's what it was the authors of the rigveda were aware of the discrepancies between the duration of the loner and the solar air and the need to add an inter calorie month for synchronizing the two because you they understand that a lunar year is different from a solar year in terms of the number of days and so on so therefore they had some mechanisms actually five systems of year are mentioned in The Vedic Corpus if you really look at it one is called sambasara which is the solar year the time taken by the sun to pass through the 12 zodiacs actually then you have Ida avastara it is the name of Savana air that is 12 months of 30 days of equal duration which is what I talked about in some of the Vedic texts so that is 360 days that is called idavasara then you have anuvasara which is the lunar year each month of which ends on the amavasiya day that is the lunar year then you have vatsara which is the name of the year with 12 lunar cycles please understand a lunar year is different from a lunar cycle lunar year is From New Moon to New Moon which is 29 and a half days whereas a lunar cycle is actually 27.32 days that is the time it takes to return to the you know such ideal duration so that is different so that is called vatsara and you have parivatsara which is the time taken by the Jupiter to pass from one sign of the zodiac to another so they had five different Notions of year which you find in the ancient Indian texts and so on so anyway I am just taking three out of them in this table as you see you have the solar year you have the Savannah year and the lunar year and solar air is 12 solar months which adds up to 365 days then you have the Savannah year which is 12 summer months of 30 days of equal duration which is 360 days then you have the lunar year which is 12 lunar months and each lunar month is 29.5 days therefore you have 354 days so you have a Yuga because this solar year and lunar year has to be now reconciled otherwise we will have a problem since we are using both the calendars in the system so 16 solar months make a yoga yoga is roughly a five solar year actually ah that will add up to 617 a month and 62 lunar months so these two months which is added every two years as you see in lunar year you have 62 lunar months which make a Yuga and you guys five years actually so this is what is done in this country you know there is this concept called adikamas every you know two and a half years there is one adika Mass which will be there so that the lunar calendar and the solar calendar is brought back to uh the same position that is what is the Yuga cycle actually of five years so it's called sambasara edavasara and anuvasra as I already mentioned so this is about the year now let's talk about the notion of a month ah you know in Surya siddhanta it defines the solar month as the time taken by the sun to Traverse or Rashi so that is called one solar month so when you have tall solar months it becomes a solar year so whereas a Chandra Masa which is a lunar month is a time interval between two new moons maybe a mouse or two full moons from purnima to purnima which I already mentioned so that is a lunar month so lunar calendar will use the lunar month solar calendar will use the solar month and as I just now showed you there will be a bit of a difference between the two so which is corrected once in two and a half years so once in five years all of them come back to the same point that ADI Kamas which I was talking about so a normal lunar year will have 12 lunar months now why am I saying a normal lunar year because there will be adhika Mass which will come once into one half years that's why I use the word normal lunar year so the names of 12 lunar months are chaitra vaishaka jesta ashada shravana bhadrapata and karthika margar and falguna and how are these names made the names are made chaitra for example means for the most part of it near the full moon day the chaitra star will be cited and so on that's all these different names are actually coming during most chaitra months the moon will be close to the star chaitra which is on the full moon day of the month similarly during the most vaishaka months the moon will be nearer the star vaishaka on the full moon day in that month and this is a logic behind nomenclature of the months in the lunar system now talking about the lunar month we have to get into the notion of pakshas so let me illustrate it with this figure so what you see here is there there is sun which is going round anyway the Moon is also going round but what happens is Moon is much faster as we found you know 29 and a half days as opposed to you know what is happening to the sun which takes little more time so what really happens is when Sun and Moon are together because they will meet together when Sun and Moon are together ah that is called amavasya okay and when the sun and the moon are diametrically opposite to each other right that is called the full moon day or the purnima right so from the time when Sun and Moon are together that is this point this entire trajectory up to this when the moon moves far away from Sun that is called sukla paksha and this one trajectory in which the moon approaches sun and then becomes one synchronizes with that that is called the Krishna paksha so the lunar month has two pakshas Shukla paksha and the Krishna paksha right so vedanga jyotisha is the first text in India to give mathematical algorithms in astronomy and there are short algorithms for finding the Titi nakshatra sun's position in the sky Etc all these are actually available in vedanga jyotisha they are approximate calculations but quick dirty and reasonably good calculation and so on now comes the notion of Titi so let us understand what is this notion of Titi as as we already saw as you find here sometimes the Sun and Moon are together sometimes the moon moves far away from the Sun Etc so which means this is a slow motion that this gap between the two slowly develops right so that is the idea behind Titi so what happens is let us say on the new moon day what happens is Sun and Moon are completely aligned that's why you don't see the moon so that is the starting point let us call it as s naught and M naught the first position so the angular separation between Sun and Moon is actually zero because they are completely aligned now what happens is after after one day after some time not exactly one day after some time because the movements are little different between Sun and the Moon if you go to next position the sun has moved here whereas the moon has moved here so now there is a difference between Sun and the Moon there is angular separation between Sun and the Moon which turns out to be 12 degrees so s 1 and M1 there is a difference of 12 degrees whereas if you take S2 and M2 this is that angular separation the sun has moved the second position here whereas moon has moved here so the angular separation is here that turns out to be 24 degrees and in 15 days it will become 180 degree that's why the moon will be here after 15 days which is called the full moon right from New Moon we have come to Full Moon now this 12 degrees is the angular separation which is called Titi the so 12 degrees is average or approximate it is slightly depending upon the you know rotation and other finer details uh That You observe in celestial objects this number is slightly around but you know one can take it as tall as a reasonable number so each Titi is nothing but an angular separation between Sun and the Moon to the extent of 12 degrees that is called Titi in the Indian tradition so we have this basic definitions of what a lunar month is what a solar month and solar Aries and what a tithi is so all these add up to developing what is called the Indian panjanga which we will see in one of the videos that follows thank you [Music] thank you