Editing Lunisolar calendar (section)

==Movable feasts in the Christian calendars, related to the lunar cycle==
The [[Gregorian calendar]] (the world's most commonly used) is a solar one but the [[Western Christianity|Western Christian churches]] use a lunar-based algorithm to determine the [[date of Easter]] and consequent [[movable feast]]s.<ref>{{cite book | last = Richards | first = E. G. | date = 2013 | chapter = Calendars | title = Explanatory Supplement to the Astronomical Almanac | edition = 3rd | editor1-last = Urban | editor1-first = Sean | editor2-last = Seidelmann | editor2-first = P. Kenneth | publisher = University Science Books | location = Mill Valley, CA | isbn = 978-1-891389-85-6 |pages= 583, 592, §15.4}}</ref> Briefly, the date is determined with respect to the [[ecclesiastical full moon]] that follows the [[ecclesiastical equinox]] in March. (These events are almost, but not quite, the same as the actual astronomical observations.) The [[Eastern Christianity|Eastern Christian churches]] have a similar algorithm that is based on the [[Julian calendar]].