April 23, 2018
tamil jothidam
1.3.8.1 Tithis
In lunar calendar, one day stands for one tithi. Tithi or lunar day is a period in which the difference between the longitudes of Moon and Sun changes by exactly 12°.
When Sun and Moon are at the same longitude, a new lunar month of 30 tithis starts. As time progresses, Moon will go ahead of Sun. When Moon’s longitude is exactly 12° greater than Sun’s longitude, the first tithi or lunar day finishes and the second tithi starts.
When Moon’s longitude is exactly 24° greater than Sun’s longitude, the second tithi finishes and the third tithi starts. When Moon’s longitude is exactly 36° greater than Sun’s longitude, the third tithi finishes and the fourth tithi starts. And so on. You can see that Sun-Moon longitude differential will be (12 x n)° after exactly n
tithis.
A lunar month consists of 30 tithis. Each month is divided into two fortnights (pakshas). During Sukla/Suddha paksha or the brighter fortnight, Moon is waxing. During this paksha, Moon is ahead of Sun by an amount that is between 0º and 180º. During Krishna/Bahula paksha or the darker fortnight, Moon is waning. During this paksha, Moon is ahead of Sun by an amount that is between 180º and 360º.
At the end of a month, Sun-Moon longitude differential will be (12 x 30)°, i.e., 360°. That means that Moon will finish one cycle around the zodiac and catch up with Sun again. So Sun and Moon will be at the same longitude again. Then a new month
starts.
We can find the tithi running on a day from the longitudes of Sun and Moon using
the following procedure.
(1) Find the difference: (Moon’s longitude – Sun’s longitude). Add 360° if the result
is negative. The result will be between 0° and 360° and will show how advanced
Moon is with respect to Sun.
(2) Divide this result by 12°. Ignore the remainder and take the quotient.
(3) Add 1 to the quotient. You get a number from 1 to 30. That will give the index of
the tithi running.
(4) Refer to Table 3 and find the name of the tithi. There are 15 tithis and the sametithis repeat in the brigher and darker fortnights. For example, it can be seen from the table that the 22th tithi out of the 30 tithis is in Krishna paksha and it is Saptami. So the 22nd tithi is “Krishna Saptami”. We write the classification of fortnight (Sukla or Krishna) first and then write tithi name. “Sukla Saptami”
stands for “Saptami” in the brighter fortnight (sukla paksha), i.e. the 7th tithi. “Krishna Saptami” stands for “Saptami” in the darker fortnight (krishna paksha), i.e. the 22nd tithi.
Example 2:
Let us say that Moon is at 24°12' in Gemini. This is (2 x 30°) + 24° 12' = 84° 12'
from the beginning of the zodiac. Let us say that Sun is at 17°46' in Scorpio. This is (7 x 30°) + 17° 46' = 227° 46' from the beginning of the zodiac. Moon – Sun = 84° 12' – 227° 46' = –(143° 34'). It is negative because Sun is at a higher longitude.
We have to add 360° to it to make it positive. It becomes 216° 26'. So this is the advancement of Moon with respect to Sun. Converting this to a decimal number, we get 216.43°. We have to divide it by 12°.
We find 216.43 ÷ 12 and the quotient is 18. So 18 tithis are over. Adding 1 to it, we get 19 and so the 19th tithi is running. Referring to Table 3, we see that this is“Chaturthi” tithi of Krishna paksha (darker fortnight). So it is “Krishna Chaturthi”.Exercise 3: Moon is at 14°43' in Leo. Sun is at 28°13' in Capricorn. Find the running tithi.
1.3.8.2 Lunar Months
We said that a new lunar month starts whenever Sun and Moon are at the same longitude. Then Moon will go ahead of Sun and, after about 29-30 days, he will catch up with Sun again. A new lunar month will start again.
These lunar months go by special names. The name of a lunar month is decided by the rasi in which Sun-Moon conjunction2 takes place. If Sun-Moon conjoin in Pisces, for example, it starts Chaitra maasa. These names come from the constellation that Moon is most likely to occupy on the full Moon day. In the month that starts when Sun and Moon conjoin in Pisces, Moon is likely to be in Chitra constellation (23°20'
2 Two planets are said to be in “conjunction” if they are exactly at the same longitude.
NOTE: However, we sometimes use this term approximately.
If two planets are in the same sign, butnot exactly at the same longitude, we still say that they are in conjunction.in Virgo to 6°40' in Libra) on the full Moon day (15th tithi – Pournimasya). So the
month is called Chaitra
A solar year has about 365.2425 days, but a lunar year only has about 355 days.Once in every 3 years, this difference accumulates to one month and an extra lunar month comes. This results in Sun-Moon conjunction coming twice in the same rasi. For example, Sun-Moon conjunction took place at 0°23' in Taurus on May 15, 1999 at 5:35:32 pm (IST) and again at 28°29' in Taurus on June 14, 1999 at 12:33:27 am (IST).
Sun-Moon conjunction in Taurus starts Jyeshtha maasa (maasa = month) as per Table 4. So 1999 had 2 Jyeshtha maasas. One is called “Nija” Jeshtha maasa and the other is called “Adhika” Jyeshtha maasa. Nija means real and adhika means extra.
An adhika maasa (extra month) comes once in every 3 years and thatsynchronizes the lunar years with solar years. This calendar has been in use in India for millennia.
In lunar calendar, one day stands for one tithi. Tithi or lunar day is a period in which the difference between the longitudes of Moon and Sun changes by exactly 12°.
When Moon’s longitude is exactly 24° greater than Sun’s longitude, the second tithi finishes and the third tithi starts. When Moon’s longitude is exactly 36° greater than Sun’s longitude, the third tithi finishes and the fourth tithi starts. And so on. You can see that Sun-Moon longitude differential will be (12 x n)° after exactly n
tithis.
A lunar month consists of 30 tithis. Each month is divided into two fortnights (pakshas). During Sukla/Suddha paksha or the brighter fortnight, Moon is waxing. During this paksha, Moon is ahead of Sun by an amount that is between 0º and 180º. During Krishna/Bahula paksha or the darker fortnight, Moon is waning. During this paksha, Moon is ahead of Sun by an amount that is between 180º and 360º.
At the end of a month, Sun-Moon longitude differential will be (12 x 30)°, i.e., 360°. That means that Moon will finish one cycle around the zodiac and catch up with Sun again. So Sun and Moon will be at the same longitude again. Then a new month
starts.
We can find the tithi running on a day from the longitudes of Sun and Moon using
the following procedure.
(1) Find the difference: (Moon’s longitude – Sun’s longitude). Add 360° if the result
is negative. The result will be between 0° and 360° and will show how advanced
Moon is with respect to Sun.
(2) Divide this result by 12°. Ignore the remainder and take the quotient.
(3) Add 1 to the quotient. You get a number from 1 to 30. That will give the index of
the tithi running.
(4) Refer to Table 3 and find the name of the tithi. There are 15 tithis and the sametithis repeat in the brigher and darker fortnights. For example, it can be seen from the table that the 22th tithi out of the 30 tithis is in Krishna paksha and it is Saptami. So the 22nd tithi is “Krishna Saptami”. We write the classification of fortnight (Sukla or Krishna) first and then write tithi name. “Sukla Saptami”
stands for “Saptami” in the brighter fortnight (sukla paksha), i.e. the 7th tithi. “Krishna Saptami” stands for “Saptami” in the darker fortnight (krishna paksha), i.e. the 22nd tithi.
Example 2:
Let us say that Moon is at 24°12' in Gemini. This is (2 x 30°) + 24° 12' = 84° 12'
from the beginning of the zodiac. Let us say that Sun is at 17°46' in Scorpio. This is (7 x 30°) + 17° 46' = 227° 46' from the beginning of the zodiac. Moon – Sun = 84° 12' – 227° 46' = –(143° 34'). It is negative because Sun is at a higher longitude.
We have to add 360° to it to make it positive. It becomes 216° 26'. So this is the advancement of Moon with respect to Sun. Converting this to a decimal number, we get 216.43°. We have to divide it by 12°.
We find 216.43 ÷ 12 and the quotient is 18. So 18 tithis are over. Adding 1 to it, we get 19 and so the 19th tithi is running. Referring to Table 3, we see that this is“Chaturthi” tithi of Krishna paksha (darker fortnight). So it is “Krishna Chaturthi”.Exercise 3: Moon is at 14°43' in Leo. Sun is at 28°13' in Capricorn. Find the running tithi.
1.3.8.2 Lunar Months
We said that a new lunar month starts whenever Sun and Moon are at the same longitude. Then Moon will go ahead of Sun and, after about 29-30 days, he will catch up with Sun again. A new lunar month will start again.
These lunar months go by special names. The name of a lunar month is decided by the rasi in which Sun-Moon conjunction2 takes place. If Sun-Moon conjoin in Pisces, for example, it starts Chaitra maasa. These names come from the constellation that Moon is most likely to occupy on the full Moon day. In the month that starts when Sun and Moon conjoin in Pisces, Moon is likely to be in Chitra constellation (23°20'
2 Two planets are said to be in “conjunction” if they are exactly at the same longitude.
NOTE: However, we sometimes use this term approximately.
If two planets are in the same sign, butnot exactly at the same longitude, we still say that they are in conjunction.in Virgo to 6°40' in Libra) on the full Moon day (15th tithi – Pournimasya). So the
month is called Chaitra
A solar year has about 365.2425 days, but a lunar year only has about 355 days.Once in every 3 years, this difference accumulates to one month and an extra lunar month comes. This results in Sun-Moon conjunction coming twice in the same rasi. For example, Sun-Moon conjunction took place at 0°23' in Taurus on May 15, 1999 at 5:35:32 pm (IST) and again at 28°29' in Taurus on June 14, 1999 at 12:33:27 am (IST).
Sun-Moon conjunction in Taurus starts Jyeshtha maasa (maasa = month) as per Table 4. So 1999 had 2 Jyeshtha maasas. One is called “Nija” Jeshtha maasa and the other is called “Adhika” Jyeshtha maasa. Nija means real and adhika means extra.
An adhika maasa (extra month) comes once in every 3 years and thatsynchronizes the lunar years with solar years. This calendar has been in use in India for millennia.
