Prior to A.D. 325, Easter was variously celebrated on different days of the week, including Friday, Saturday, and Sunday. In that year, the Council of Nicaea was convened by emperor Constantine. It issued the Easter Rule which states that Easter shall be celebrated on the first Sunday that occurs after the first full moon on or after the vernal equinox. However, a caveat must be introduced here. The "full moon" in the rule is the ecclesiastical full moon, which is defined as the fourteenth day of a tabular lunation, where day 1 corresponds to the ecclesiastical New Moon. It does not always occur on the same date as the astronomical full moon. The ecclesiastical "vernal equinox" is always on March 21. Therefore, Easter must be celebrated on a Sunday between the dates of March 22 and April 25.
In the Western Church, Easter has not fallen on the earliest of the 35 possible dates, March 22nd, since 1818, and will not do so again until 2285. This year, Easter falls on March 23rd and will not do so again until 2160. Easter last fell on the latest possible date, April 25th in 1943 and will next fall on that date in 2038.
Featured in this blog entry is the Walt Disney Classics Collection release of Thumper and Miss Bunny, part of the Twitterpated Scene released in February 2002.