New moon western horizon shortly after sunset and before moonset. A lunation or synodic month is the average time from one new moon to the next. In the J2000.0 epoch, the average length of a lunation is 29.530588 days (or 29 days, 12 hours, 44 minutes, and 2.8 seconds). However, the length of any one synodic month can vary from 29.26 to 29.80 days due to the perturbing effects of the Sun's gravity on the Moon's eccentric orbit. In a lunar calendar, each month corresponds to a lunation. Each lunar cycle can be assigned a unique lunation number to identify it. The
Month calendar consists of both a lunar calendar and a solar calendar. The Khmer solar calendar is used more commonly than the lunar calendar. There are 12 months and the numbers of days follow the Julian and Gregorian calendar. The Khmer lunar calendar contains 12 months; however, the eighth month is repeated (as a "leap-month") every two or three years, making 13 months instead of 12. The Tongan calendar is based on the cycles of the moon around the earth in one year. The months are: The Sinhala calendar is the Buddhist calendar in Sri Lanka with Sinhala names. Each full