Surya Siddhanta is an ancient text of astronomy and believed to be written around 400 AD. It is one of the oldest surviving
Sanskrit texts on astronomy. This treatise contains the rules and formulas used in the creation of the
Hindu solar and lunar calendars.
The author of Surya Siddhanta is unknown. The text is still employed for creating the Panchang, which is a traditional Hindu Vedic calendar containing the days of the religious, cultural and astronomical events. The text also contains the methods for calculating the celestial longitude of sun and the planetary bodies.
A striking feature of Surya Siddhanta is the mention of the sun being the center of the solar system, a fact discovered by the European scientists almost 1,000 years later. Many of the calculations described in this text match with the modern methods.
