Astronomy is the basis of Astrology, and as the Shastras state, Siddhanta is the mathematical component of Jyotisha. One must study the Siddhanta to understand how the ancient Maharshis and Acharyas computed the Graha positions. Learning the evolution and history of a subject is as much important as the current state of the subject.

The knowledge of computation of planetary positions in the sky is only a starting point in the entire field of astronomy. After covering the method of determining the Longitude and Latitude of a Graha, Suryasiddhanta moves on to apply that in ascertaining astronomical events such as Yuti (conjunction), Astangata (combustion), Grahayuddha (planetary fights), Vakragati (retrogression), Grahana (eclipse), and several others. This book explores the astronomical and astrological aspects of such events.

Also covered are an introduction to Ankashastra, or Vedic Numerology, which is based on the Year, Month, Day, and Hora lord. Siddhanta texts lay down the principles of determining them but are hardly used today. I hope this book will serve as a guide to the mathematical-minded Jyotishis to the Astronomical aspects of Jyotisha.