The movement of the earths axis as it moves around the Sun causes the seasons of man to change. When any point on earth is closest to the Sun it gives rise to the longest day of the year. Similarly when furthest away it gives rise to the shortest day, two occurrences which are exactly six months apart, occurring in the seasons of summer and winter and is termed the summer and winter solstices.
These two occurrences correspond to the tropical position of 0º Cancer and 0º Capricorn. The Sun’s movement from Cancer to Capricorn is termed the southern course of the Sun (Dakṣiṇāyana) whereas the other is termed the northern course (Uttarāyana).
Exactly halfway between these two occurrences occurs a day consisting of the length of night being the exact same as that of the day length. The latter is known as an equinox and two of them occur every year, also being six months apart at the tropical positions of 0º Aries and 0º Libra. These four days in a year act as a means to know the junction points of the seasons on earth and in ancient times were used as reference points to measure the position of the stars.
Whilst these solstices and equinoxes are a means to understand the seasons on earth, the same positions as seen in the Sidereal Zodiac depict the seasons of the Deva or God. Knowing this is a means of predicting the quality of time for all those born. At present the Sidereal positions do not correspond to the Tropical positions of these occurrences and are separated by ~23 degrees.
Six seasons (ṛtu) are mentioned in the ancient literature. Beginning from the Suns entry into Sidereal Pisces, the signs of Pisces and Aries correspond to Vasanta (spring), Taurus and Gemini to Grīṣma (summer), Cancer and Leo to Varśa (rainy season), Ṣarad (autumn), Hemanta (pre-winter) and Ṣiṣira (winter). These six seasons are related to the ṣaḍkarma (six types of karma).
Ayanāmśa
To date, there are about five different starting positions of the Zodiac in popular vogue by Jyotiṣa. These vary for the most only very little, by a few degrees in number, whilst some like the Tropical zodiac varies by more than 23 degrees.
Whilst the Tropical zodiac is a zodiac in its own right and its accuracy is unquestionable, Vedic Astrologers who predict by the actual star-position, and thus also ascertain the beginning of the zodiac based on them, are in a dilemma when it comes to ascertaining the correct starting point of the zodiac. The following are among the most popular that have suggested various starting points: i) Lahiri, ii) BV Raman, iii) Krishnamurty Paddhati, iv) Fagan-Bradley and also the author JN Bhasin (v).
Most of the mentioned have in common that they were serious practicing astrologers. All were trying to ascertain an accurate zero degree of the Ayanāmśa, one thing that had last been ascertained by the Lahiri committee in the 1950’. Among these, the renowned astrologer BV Raman, despite having an Ayanāmśa to his name, never officially published the same, yet this was done by his students. Further it has been seen that he in fact applied this adjustment solely to the moons position and not the remaining planets. This continues to create doubt among astrologers.
The remaining have values quite close to Lahiri.
The main efforts made by astrologers have been to ascertain which degree of variation from the Tropical zodiac. More appropriately, they have all been trying to emulate the actual star positions and thus also the beginning of Aries.
Putting Astrological acumen aside, as today even astrologers disagree about astrological principles, the task of the day is to ascertain where the zodiac should start from.
To establish this most comment the Sūrya Siddhānta as being the accurate source for the zodiac. Yet, today most quote a different source and lay claim to Lahiri’s Ayanāmśa being different from the Sūrya Siddhānta.
These questions will be examined in the following paragraphs.
Raivata pakṣa... what is it?
Whenever there is question of ascertaining a scriptural source for the starting point of the zodiac, the reference comes from the Sūrya Siddhānta. Sūrya Siddhānta is the most comprehensive treatise on astronomy and has been the basis of astronomers such as Arabhyata, Bhāskara, etc.
Pakṣa refers to the fortnight. This can be either bright or dark depending on whether the Moon is moving away or towards the sun respectively. A Pakṣa consists of 15 lunar days consisting of 12 degrees each. This amounts to 180 degrees in total. Therefore, Raivata Pakṣa refers to 180 degrees opposite Revatī. Revatī here refers to the star Revatī, and not specifically the entire constellation (Nakṣatra) which presides between 16 º40’ Pisces to 30º Pisces, but to the specific star in Revatī which makes up its position in space. This specific reference to the star is termed Yogatara.
According to some
This is likely because Sūrya Siddhānta does refer to Revatī when explaining the Ayanāmśa:
तेषां तु परिवर्तेन पौष्णान्ते भगणः स्मृतः॥१।२७॥
teṣāṁ tu parivartena pauṣṇānte bhagaṇaḥ smṛtaḥ||1|27||
By their [the planets] movement, the revolution is accounted complete at the end of the asterism Revati.
Based on the positions of the stars, Revatī’s Yogatara has been ascertained to be that of Zeta Piscium. This is currently estimated at the Tropical position of 5º51’ Pisces, which some recognize as the star Zeta Piscium (Struve 100).
Chaitrā Pakṣa
If the Sūrya Siddhānta states that the zodiac proceeds from the star Revatī, why would there be any question of another starting point of the zodiac? A starting point beginning from 180º opposite the star Chitrā is widely in vogue and has formed the basis of the widely used Lahiri Ayanāmśa.
To understand this, a closer study of the Sūrya Siddhānta becomes required. In the chapter explaining the positions of the stars which form the Nakṣatra
Therefore, the Sūrya Siddhānta was not wrong in stating that the beginning of the zodiac follows after Revatī, but had it not been for the later specification of the actual star position of Revatī, we would not know that it starts 0º10’ after Revatī! Therefore, any mention of a Raivata pakṣa Ayanāmśa must take this difference into account.
Studying the star positions specified in the Sūrya Siddhānta, we find a means of establishing the Ayanāmśa at any given time based on the available data of star positions. Thus should the visibility of one star become faint at some point in time, we can rely on other stars to establish the exact beginning of the zodiac.
Most prominently we find that the star Chitrā has been assigned to 400’ (6º40’) into the 14th portion of space (23º20’ Virgo to 6º40’ Libra). This position corresponds to exactly 0º Libra. Since 0º Libra is exactly opposite the beginning of Aries (0º Aries) this would be a very accurate means of ascertaining the beginning of the zodiac. The positions of the other stars are tabulated in the Chapter on Nakṣatra of this book.
It is therefore evident, that the best method to ascertain the beginning of the Ayanāmśa is by finding the placement of Chitrā.
om tat sat
