Astrology is commonly called the Shastra which tells us the facts about the planets. “Jyotisham Suryadi grahana bodhakam shastram” This is a very common saying it means that the science which makes the people know Sun and the other stars and planets and understand they are astrology. It is the science of time that records the life and its reactions to planetary radiation. Astrology comprises of “Skandhtrya”. These three Skandha are Hora, Samhita and Ganita. Ganita is also called Siddhanta. Let us look at these in some details: Siddhanta first. The mathematics of astrology is basically Siddhanta. Generally we come across five Siddhantas.
These Siddhantas are of use in the preparation of mathematical tables the almanacs or the Panchanga.