Lunar calendar traces of its origin in the earlier lunar calendar, which continued to be used alongside it for religious and agricultural purposes. Present-day lunisolar calendars include the Chinese, Hindu, and Thai calendars. Synodic months are 29 or 30 days in length, making a lunar year of 12 months about 11 days shorter than a solar year. Some lunar calendars do not use intercalation, such as most Islamic calendars. For those that do, such as the Hebrew calendar, the most common form of intercalation is to add an additional month every second or third year. Some lunisolar calendars are also calibrated by
Adhik Maas Puruśottama Māsa, it is said that the name was given by Lord Vishnu as his name to this month. The solar year is made up of 365 days and about 6 hours, and the lunar year is made up of 354 days. Thus there is a gap of 11 days, 1 hour, 31 minutes and 12 seconds between the lunar and the solar years. As this gap accumulates each year, it approximates in three years to one month. No "adhik mas" falls during Margsheersh to Magh. A case of Adhik Karttik is extremely rare, but in the 250-year span (1901-2150