Islamic calendar lunar months begin precisely at the time of the monthly "conjunction", when the Moon is located most directly between the Earth and the Sun. The month is defined as the average duration of a revolution of the Moon around the Earth (29.53 days). By convention, months of 30 days and 29 days succeed each other, adding up over two successive months to 59 full days. This leaves only a small monthly variation of 44 minutes to account for, which adds up to a total of 24 hours (i.e., the equivalent of one full day) in 2.73 years. To settle accounts,
Lunar day daylight at a given point on the Moon would last approximately two weeks from beginning to end, followed by approximately two weeks of night. In some lunar calendars, such as the Hindu calendar, a lunar day, or "tithi", is defined as 1/30th of a lunar month, or the time it takes for the longitudinal angle between the Moon and the Sun to increase by 12 degrees. By this definition, lunar days generally vary in duration. Lunar day A lunar day is the period of time for Earth's Moon to complete one rotation on its axis with respect to the Sun.