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
April 2015 lunar eclipse April 2015 lunar eclipse A total lunar eclipse took place on 4 April 2015. It is the former of two total lunar eclipses in 2015, and the third in a "tetrad" (four total lunar eclipses in series). Other eclipses in the tetrad are those of 15 April 2014, 8 October 2014, and 28 September 2015. This is the 30th member of Lunar Saros 132, and the first total eclipse. The previous event was the March 1997 lunar eclipse, being slightly partial. Totality lasted only 4 minutes and 44 seconds, making it the shortest lunar totality in almost five centuries since