Lunar calendar or crescent moons and others employing detailed calculations. Since each lunation is approximately days (29 days, 12 hours, 44 minutes, 3 seconds, or days), it is common for the months of a lunar calendar to alternate between 29 and 30 days. Since the period of twelve such lunations, a lunar year, is only 354 days, 8 hours, 48 minutes, 34 seconds ( days), purely lunar calendars lose around 11 days per year relative to the Gregorian calendar. In purely lunar calendars like the Islamic calendar, the lack of intercalation causes the lunar months to cycle through all the seasons of
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