Easter is a moveable feast, meaning it is not fixed in relation to the civil calendar. The First Council of Nicaea (325) established the date of Easter as the first Sunday after the full moon (the Paschal Full Moon) following the northern hemisphere's vernal equinox. Ecclesiastically, the equinox is reckoned to be on March 21 (even though the equinox occurs, astronomically speaking, on March 20 in most years), and the "Full Moon" is not necessarily the astronomically correct date. The date of Easter therefore varies between March 22 and April 25. Eastern Christianity bases its calculations on the Julian Calendar whose March 21 corresponds, during the 21st century, to the 3rd of April in the Gregorian Calendar, in which calendar their celebration of Easter therefore varies between April 4 and May 8.
Date of Easter
Dates for Easter
1982–2022
In Gregorian dates
Year Western Eastern
1982 April 11 April 18
1983 April 3 May 8
1984 April 22
1985 April 7 April 14
1986 March 30 May 4
1987 April 19
1988 April 3 April 10
1989 March 26 April 30
1990 April 15
1991 March 31 April 7
1992 April 19 April 26
1993 April 11 April 18
1994 April 3 May 1
1995 April 16 April 23
1996 April 7 April 14
1997 March 30 April 27
1998 April 12 April 19
1999 April 4 April 11
2000 April 23 April 30
2001 April 15
2002 March 31 May 5
2003 April 20 April 27
2004 April 11
2005 March 27 May 1
2006 April 16 April 23
2007 April 8
2008 March 23 April 27
2009 April 12 April 19
2010 April 4
2011 April 24
2012 April 8 April 15
2013 March 31 May 5
2014 April 20
2015 April 5 April 12
2016 March 27 May 1
2017 April 16
2018 April 1 April 8
2019 April 21 April 28
2020 April 12 April 19
2021 April 4 May 2
2022 April 17 April 24
Easter and the holidays that are related to it are moveable feasts, in that they do not fall on a fixed date in the Gregorian or Julian calendars (both of which follow the cycle of the sun and the seasons). Instead, the date for Easter is determined on a lunisolar calendar similar to the Hebrew calendar.
In Western Christianity, using the Gregorian calendar, Easter always falls on a Sunday between March 22 and April 25, inclusively.[43] The following day, Easter Monday, is a legal holiday in many countries with predominantly Christian traditions. In Eastern Orthodox Churches — which continue to use the Julian calendar for religious dating — Easter also falls on a Sunday between March 22 and April 25, inclusive, of the Julian calendar. (The Julian calendar is no longer used as the civil calendar of the countries where Eastern Christian traditions predominate.) In terms of the Gregorian calendar, due to the 13 day difference between the calendars between 1900 and 2099, these dates are between April 4 and May 8, inclusive. Among the Oriental Orthodox some churches have changed from the Julian to the Gregorian calendar and the date for Easter as for other fixed and moveable feasts is the same as in the Western Church.
The precise date of Easter has at times been a matter for contention. At the First Council of Nicaea in 325 it was decided that all Christian churches would celebrate Easter on the same day, which would be computed independently of any Jewish calculations to determine the date of Passover. It is however probable (though no contemporary account of the Council's decisions has survived) that no method of determining the date was specified by the Council. Epiphanius of Salamis wrote in the mid-4th century: :...the emperor...convened a council of 318 bishops...in the city of Nicea...They passed certain ecclesiastical canons at the council besides, and at the same time decreed in regard to the Passover that there must be one unanimous concord on the celebration of God's holy and supremely excellent day. For it was variously observed by people....
In the years following the council, the computational system that was worked out by the church of Alexandria came to be normative. It took a while for the Alexandrian rules to be adopted throughout Christian Europe, however. The Church of Rome continued to use an 84-year lunisolar calendar cycle from the late third century until 457. The Church of Rome continued to use its own methods until the 6th century, when it may have adopted the Alexandrian method as converted into the Julian calendar by Dionysius Exiguus (certain proof of this does not exist until the ninth century). Early Christians in Britain and Ireland also used a late third century Roman 84-year cycle. This was replaced by the Alexandrian method in the course of the 7th and 8th centuries. Churches in western continental Europe used a late Roman method until the late 8th century during the reign of Charlemagne, when they finally adopted the Alexandrian method. However, with the adoption of the Gregorian calendar by the Catholic Church in 1582 and the continuing use of the Julian calendar by Eastern Orthodox and most Oriental Orthodox Churches, the date on which Easter is celebrated again deviated, and the divergence continues to this day.
Computations
Main article: Computus
The rule has since the 4th century been phrased as Easter is observed on the Sunday after the first full moon on or after the day of the vernal equinox. However, this does not reflect the actual ecclesiastical rules precisely. One reason for this is that the full moon involved (called the Paschal full moon) is not an astronomical full moon, but the 14th day of a calendar lunar month. Another difference is that the astronomical vernal equinox is a natural astronomical phenomenon, which can fall on March 19, 20, or 21, while the ecclesiastical date is fixed by convention on March 21.
In applying the ecclesiastical rules, Christian Churches use March 21 as the starting point in determining the date of Easter, from which they find the next full moon, etc. The Eastern Orthodox and Oriental Orthodox Churches continue to use the Julian calendar. Their starting point in determining the date of Orthodox Easter is also March 21, but according to the Julian reckoning, which corresponds to April 3 in the Gregorian calendar. In addition, the lunar tables of the Julian calendar are 4 days (sometimes 5 days) behind those of the Gregorian calendar. The 14th day of the lunar month according to the Gregorian system is only the 9th or 10th day according to the Julian. The result of this combination of solar and lunar discrepancies is divergence in the date of Easter in most years.
The actual calculations for the date of Easter are somewhat complicated, but can be described briefly as follows:
Easter is determined on the basis of lunisolar cycles. The lunar year consists of 30-day and 29-day lunar months, generally alternating, with an embolismic month added periodically to bring the lunar cycle into line with the solar cycle. In each solar year (January 1 to December 31), the lunar month beginning with an ecclesiastical new moon falling in the 29-day period from March 8 to April 5 inclusive is designated as the Paschal lunar month for that year. Easter is the 3rd Sunday in the Paschal lunar month, or, in other words, the Sunday after the Paschal lunar month's 14th day. The 14th of the Paschal lunar month is designated by convention as the Paschal full moon, although the 14th of the lunar month may differ from the date of the astronomical full moon by up to two days. Since the ecclesiastical new moon falls on a date from March 8 to April 5 inclusive, the Paschal full moon (the 14th of that lunar month) must fall on a date from March 21 to April 18 inclusive.
Accordingly, Gregorian Easter can fall on 35 possible dates - between March 22 and April 25 inclusive.[48] It last fell on March 22 in 1818, and will not do so again until 2285. It fell on March 23 in 2008, but will not do so again until 2160. Easter last fell on the latest possible date, April 25, in 1943 and will next fall on that date in 2038. However, it will fall on April 24, just one day before this latest possible date, in 2011. The cycle of Easter dates repeats after exactly 5,700,000 years, with April 19 being the most common date, happening 220,400 times or 3.9%, compared to the median for all dates of 189,525 times or 3.3%.
The Gregorian calculation of Easter was based on a method devised by the Calabrian doctor Aloysius Lilius (or Lilio) for adjusting the epacts of the moon,[49] and has been adopted by almost all Western Christians and by Western countries who celebrate national holidays at Easter. For the British Empire and colonies, a determination of the date of Easter Sunday using Golden Numbers and Sunday letters was defined by the Calendar (New Style) Act 1750 with its Annexe. This was designed to exactly match the Gregorian calculation.
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