Siddhanta is the foundational branch dedicated to mathematical and computational astronomy. It provides the scientific framework required to calculate the precise positions of celestial bodies, which is essential for creating accurate birth charts and calendars.
Core Functions and Scope
- Planetary Calculations: It includes complex formulas for determining the mean and true longitudes of the seven classical planets (Grahas), including the Sun and Moon.
- Time Measurement: It defines vast units of time, from the smallest unit (truti) to the largest cosmic cycles known as Kalpas and Yugas.
- Cosmic Events: It provides the mathematical basis for predicting solar and lunar eclipses, planetary conjunctions, and the precession of the equinoxes.
- Calendrical Basis: It is the technical backbone for the Panchang (Hindu almanac), used to determine auspicious timings for rituals and daily activities.
The Three Levels of Calculation Texts
In practice, Siddhantic knowledge is categorized by the time spans they cover:
- Siddhanta: Comprehensive treatises that calculate planetary motions starting from the beginning of a Kalpa (the creation of the universe).
- Tantra: Texts that use a Mahayuga (a cycle of 4,320,000 years) as the starting point for calculations.
- Karana: Practical, concise handbooks that use a more recent epoch (a specific date) to simplify daily calculations for astrologers.
Major Texts and Authors
- Surya Siddhanta: The most authoritative and widely used text, traditionally attributed to a divine source. It covers trigonometry, spherical geometry, and precise orbital parameters.
- Pancha-Siddhantika: Compiled by Varahamihira (6th century CE), this work summarizes five ancient systems: Paitamaha, Vashishta, Surya, Romaka, and Paulisha.
- Aryabhatiya: Written by Aryabhata, this seminal work introduced advanced mathematical concepts like the sine table to Indian astronomy.
Without the Siddhanta branch, the other two branches of Jyotisha—Hora (predictive astrology) and Samhita (mundane astrology)—would lack the necessary data to make any predictions.
