Chandashastra

Chandashastra is an ancient Indian text that deals with the study of time, specifically the calculation and measurement of time according to the Hindu calendar. It is a branch of Vedanga, the auxiliary disciplines that support the understanding of the Vedas. The term "Chandashastra" is derived from the Sanskrit words "chanda," meaning meter or time, and "shastra," meaning science or doctrine.

The Chandashastra is attributed to the sage Lagadha, who is believed to have lived around the 1st millennium BCE. The text is primarily concerned with the prosody and meter of Vedic hymns, but it also delves into the calculation of time, including the determination of lunar months, solar years, and the intercalation of months to keep the lunar and solar calendars in sync. This is crucial for the observance of religious festivals and rituals, which are often tied to specific lunar phases or solar positions.

The Chandashastra is one of the earliest known texts that systematically discusses the concept of time in Indian astronomy and astrology. It provides detailed rules and formulas for calculating the lengths of days, months, and years, as well as the positions of the sun, moon, and planets. These calculations are based on observational astronomy and mathematical principles, reflecting the advanced knowledge of timekeeping and celestial mechanics in ancient India.

Over time, the principles outlined in the Chandashastra have been incorporated into other texts and traditions, influencing the development of Indian astronomy, astrology, and calendar systems. The text remains a significant historical document, offering insights into the scientific and religious practices of ancient India.