Tithi
![The astornomical basis of the Hindu lunar day](/Images/godic/202502/16/-Tithi.ogv5429.jpg")
![image to understand the calculation of tithi](/Images/godic/202502/16/Tithi_Calculation5429.jpg")
In Vedic timekeeping, a tithi (also spelled thithi) is a lunar day, or the time it takes for the longitudinal angle between the Moon and the Sun to increase by 12°. Tithis begin at varying times of day and vary in duration from approximately 19 to approximately 26 hours.