List of dates for Easter

The date of Easter varies in a manner too complicated to summarize in a simple formula, and in most years differs between the usage of Western and Eastern Christianity (and the usages of the countries where they are respectively more influential).

Following the Council of Nicaea, the date for Easter was completely divorced from the Jewish calendar and its computations for Passover. Thereafter, in principle, Easter fell on the Sunday following the full moon that follows the Northern spring equinox (the so-called Paschal Full Moon). However, the vernal equinox and the full moon were not determined by astronomical observation. Instead, the Spring Equinox was fixed to fall on the 21st day of March, while the full moon (known as the ecclesiastical full moon) was fixed at 14 days after the beginning of the ecclesiastical lunar month (known as the ecclesiastical new moon). Easter thus falls on the Sunday after the ecclesiastical full moon. The computus is the procedure of determining the first Sunday after the first ecclesiastical full moon falling on or after 21 March and the difficulty arose from doing this over the span of centuries without accurate means of measuring the precise solar or lunar years.

The model that was worked out assumes that 19 tropical years have the same duration as 235 synodic months (modern value: 234.997).^[1]

Since the 16th century, there have been differences in the calculation of Easter between the Western and Eastern Churches. The Roman Catholic Church since 1583 has been using 21 March under the Gregorian calendar to calculate the date of Easter, while the Eastern Orthodox continued and continue to use 20 March under the Julian Calendar. The Catholic and Protestant denominations thus use an ecclesiastical full moon that occurs four to five days earlier than the eastern one.

Earliest Easter

Western/Gregorian

In 1818 the Paschal Full Moon fell on Saturday March 21 (the equinox). Therefore the following day, March 22, was Easter. It will not fall as early again until 2285 - a span of 467 years. A notably early, but not as such, Easter between 1818 and 2285 is 2008's Easter - March 23. It last occurred that early in 1913, and will occur again in 2160, a 95 and 152-year gap, respectively.

Orthodox/ Julian

The earliest dates for Orthodox Easter between 1875 and 2099 are, 22 March 1915 and 22 March 2010. Both dates are equivalent to April 4 in the Gregorian Calendar.

Latest Easter

Western/Gregorian

In 1943 an ecclesiastical Full Moon fell on Saturday March 20. As this was just before the equinox it was the next Full Moon (the Paschal Full Moon) on Sunday, April 18 which determined the date of Easter - April 25. It will not fall as late again until 2038 - a span of 95 years. The 2nd latest date, April 24, most recently occurred in 2011. This last occurred in 1859 and will not happen again until 2095 - 152 and 84 years, respectively.

Orthodox/Julian

The latest dates for Orthodox Easter between 1875 and 2099 are, 25 April 1983 and 25 April 2078. Both dates are equivalent to May 8 in the Gregorian Calendar.

Western and Orthodox Easter on the same date

Despite using calendars that are apart by 13 days, Easter 2014 fell on the same date. According to the Western (Gregorian) calendar, the first Paschal Full Moon after the Spring Equinox (March 21) fell on Monday, April 14, 2014. The following Sunday, April 20, was therefore Easter Day.

According to the Orthodox (Julian) calendar (which is 13 days behind the Gregorian calendar) the Spring Equinox also falls on March 21. However, in the Gregorian Calendar this is April 3. The first Orthodox Full Moon after the Equinox falls on (Julian) Wednesday April 2, 2014 (Gregorian April 15). The following Sunday, (Julian) April 7, is therefore Easter Day (Gregorian April 20).

Range of dates for Western and Orthodox Easter

Both calendars (Gregorian and Julian) calculate Easter as falling on dates between March 22 and April 25. However, because of the 13 day difference, any member of an Orthodox church would observe that the Western Easter falls between March 9 and April 12 on the Julian calendar. Conversely, any member of a Western church would observe that Orthodox Easter falls between April 4 and May 8 on the Gregorian calendar.

Beginning March 14, 2100 (Gregorian), the difference between the Julian and Gregorian calendars will increase to 14 days.

The accompanying table provides both sets of dates, for recent decades and forthcoming years - see the Computus article for more details on the calculation.

Notes

A much larger list of dates can be found at http://tlarsen2.tripod.com/thomaslarsen/easterdates.html