Hebrew calendar (astronomically called a lunar conjunction and, in Hebrew, a molad) is the moment at which the sun and moon are aligned horizontally with respect to a north-south line (technically, they have the same ecliptical longitude). The period between two new moons is a synodic month. The actual length of a synodic month varies from about 29 days 6 hours and 30 minutes (29.27 days) to about 29 days and 20 hours (29.83 days), a variation range of about 13 hours and 30 minutes. Accordingly, for convenience, a long-term average length, identical to the mean synodic month of ancient times (also
Siṃha month of Karkaṭa, and followed by the solar month of Kanyā. The Simha month is called "Avani" in the Tamil Hindu calendar. The ancient and medieval era Sanskrit texts of India vary in their calculations about the duration of Simha, just like they do with other months. For example, the "Surya Siddhanta", dated to c. 400 CE, calculates the duration of Simha to be 31 days, 0 hours, 26 minutes and 48 seconds. In contrast, the "Arya Siddhanta" calculates the duration of the Simha month to be 31 days, 2 hours, 5 minutes and 31 seconds. The Indian solar month