In Vedic civilization mainly used the Nakshatra Chakra for astrological prediction. The same can be observed in epics as well.Now the question is – What is this system? And how they used it? Let me try to answer it as per my limited knowledge.
First we should accept the following points -
• Originally Nakshatra division was related to path of Moon, and in that unequal division, the 28 Nakshatra scheme was used. But later for mathematical clarity the Nakshatra divisions were associated with ecliptic (movement of earth/sun). Thus came the definition of Nakshatra as 1/27 th of the ecliptic, which is equal to 13 deg 20 min.
Since Nakshatra Chakra is an equal division of the ecliptic only 27 Nakshatras are important in this system. The concept of Degree-minute was present, as evident from the Mahabharata sloka bit – "KashtaH kala muhoortascha diva ratristhatha lavaH". Here, Kala = Minute. Bhaga = Degree (This is not mentioned in the sloka)
• The 28 Nakshatra scheme, that is associated with the path of moon, will not be discussed here. (Due to the fluctuations in the path of Moon this system can not give correct results for long). The 27 Nakshatra scheme (as told in Titireeya Samhita) is closer to the system we follow today. This is the reason for neglecting the 28 Nakshatra scheme in this study.
• The movement of equinox through Nakshatras was observed in Vedic period. This was possible only if a fixed frame of Reference of Nakshatra Chakra was in use. That means the Nakshatra Chakra used in Vedic period was not Tropical but Sidereal in nature.
• Thus, Nakshatra Chakra is the fixed frame of reference based on which the movements of planets were studied.
• The Sidereal Year was also in use and many other year systems as well. The use of Sidereal year is clearly indicated by the Titireeya Brahmana sloka bit "Nakshtrani Savatsarasya Pratishta", meaning, "The year is calculated based on Nakshatras (fixed stellar divisions)".
• The importance of 360 day Savana year (used in Nakshatra Dasa) is due to the (intentional) association of the ecliptic (movement of Sun) with Nakshatras done by Rishis. Sun stays in a star for 13.333 days on an average. Multiplying it with 27 we get – 360 days.
Classifications used to study the nature of Nakshatras
1) Nakshatra devatas were assigned I don't want to discuss here in details, you can get these details from any slandered text of astrology.
2) Male-Female classification
Nakshatra names that end with i, e or a where considered female and others male. Mrigaseersha and Moola were considered Kleeba (impotent) nakshatras.
3) Kula-Upakula-Kulopakula classification
Three types of Nakshatras may fall into a lunar month division of the zodiac. The Nakshatra name based on which the lunar month (Aswini, Krittika, Mrigaseersha etc) is named, that Nakshatras are called Kula. In other words, in the corresponding lunar months full moon occurs in those Nakshatras. The next Nakshatra is called Upakula and the third Kulopakula. The same strategy for all the lunar months.
4) Sthiradi classification.
Nakshatras were classified into 5 categories and lordship assigned to planets. This lordship is different from the one considered now. But here the thing to remember is that the meaning of Stiradi names assigned to Nakshatras were considered more important than this lordship. The list is given below:
Sthira (fixed) – Utra, Utrada, Uttara Bhadrapada, Rohini - Sun
Chara (movable) - Swati, Punarvasu, Tiruvonam, Srevishta, Satabhishak - Moon
Ugram (Fierce) – Purva Phalguni, Purva Ashada, Purva Bhadrapada, Bharani, Magha – Mars
Misram (Mixed) – Visakha , Krittika - Mercury
Kshipram (Fast) – Hasta, Aswani, Pushya - Jupitor
Mridu (Soft) – Mrigaseersha, Ravati, Chitra, Anuradha - Venus
Teekshnam (Sharp) – Moola, Jyeshta, Ardra, Aslesha - Saturn
This classification was used to understand the nature of Nakshatra and the people born in them.
5) Nakshatra Purusha
Just like the Kalapurusha (Rasi purusha) concept related to Rasis, Nakshatra purusha concept was in use. (Ref. Mahabharata) We may be able to find many more classifications if we are willing to search the allied Vedic literature. I think the above is sufficient to have a start
4-fold prediction system
The Nakshatra Chakra, Planets including Ra and Ke, Benefic-Malefic classification of planets, Exaltation and debilitation of planets (in Nakshatra Chakra), eclipsing of Sun and Moon, Retrograde of planets The ephemeris components such as Nakshatra-Tithi-Vara-Karana-Nityayoga, waxing and waning of Moon – all these were considered to make elaborate prediction. If we look at the epics we could find that a 4-fold system was in use. That means, predictions were given for-
1) Nakshatra Lagna (Ascendant star)
2) Placement of Planets in Nakshatras
3) Conjunction of Planets (in Nakshatras)
4) Janma-Sampad-Vipat etc naming of Nakshatra was in use.
This might have been in use some what similar to the Bhava system. It is not certain, whether the Drishti of Plants was considered in that period or not. If it was, then Drishti should have meant, Drishti between plants in opposite Nakshatras. An elaborate study will reveal the intricacies of this 4-fold system of Nakshatra based prediction system that was in use.
An elaborate study of the Nakshatra Chakra (27 Nakshatra scheme) based prediction system used in Vedic literature and Epics calls for a detailed study. Hope that before the system is lost someone will come forward to collect, arrange, explore and elaborate this original system of Nakshatra based prediction.