Molad based on a constant interval cycle that is widely but incorrectly regarded as an approximation of the time in Jerusalem of the mean lunar conjunction. Each "molad" moment occurs exactly 29 days 12 hours 44 minutes and 3+/ seconds (or, equivalently, 29 days 12 hours and 44+/ minutes) after the previous "molad" moment. This interval is numerically exactly the same as the length of the mean synodic month that was published by Ptolemy in the Almagest, who cited Hipparchus as its source. Although in the era of Hipparchus (2nd century BC) this interval was equal to the average time between
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.