This article is about how the date of Easter is calculated. For actual dates of Easter from 2015 to 2030, see List of dates for Easter.
As a moveable feast,[1][2] the date of Easter is determined in each year through a calculation known as computus (Latin for 'computation').[3] Easter is celebrated on the first Sunday after the Paschal full moon (a mathematical approximation of the first astronomical full moon, on or after 21 March – itself a fixed approximation of the March equinox). Determining this date in advance requires a correlation between the lunar months and the solar year, while also accounting for the month, date, and weekday of the Julian or Gregorian calendar.[4] The complexity of the algorithm arises because of the desire to associate the date of Easter with the date of the Jewish feast of Passover which, Christians believe, is when Jesus was crucified.[5]
It was originally feasible for the entire Christian Church to receive the date of Easter each year through an annual announcement by the pope. By the early third century, however, communications in the Roman Empire had deteriorated to the point that the church put great value in a system that would allow the clergy to determine the date for themselves, independently yet consistently.[6] Additionally, the church wished to eliminate dependencies on the Hebrew calendar, by deriving the date for Easter directly from the March equinox.[7]
In The Reckoning of Time (725), Bede uses computus as a general term for any sort of calculation, although he refers to the Easter cycles of Theophilus as a "Paschal computus." By the end of the 8th century, computus came to refer specifically to the calculation of time.[8]
The calculations produce different results depending on whether the Julian calendar or the Gregorian calendar is used. For this reason, the Catholic Church and Protestant churches (which follow the Gregorian calendar) celebrate Easter on a different date from that of the Eastern and Oriental Orthodoxy (which follow the Julian calendar). It was the drift of 21 March from the observed equinox that led to the Gregorian reform of the calendar, to bring them back into line.
^Ayto 2009, p. 123.
^Peterson 2015, p. 468.
^Bede 1999, p. xviii.
^Bede 1999, pp. xviii–xx.
^John 19:14
^Bede 1999, p. xx.
^Bede 1999, p. xxxvi.
^Bede 1999, pp. 425–426, Appendix 4: A Note on the Term Computus.
moveable feast, the dateofEaster is determined in each year through a calculation known as computus (Latin for 'computation'). Easter is celebrated on...
Easter, also called Pascha (Aramaic, Greek, Latin) or Resurrection Sunday, is a Christian festival and cultural holiday commemorating the resurrection...
Reform of the dateofEaster refers to proposals to change the date for the annual celebration ofEaster. These proposals include setting a fixed date or...
is a list of dates for Easter. The Easter dates also affect when Ash Wednesday, Maundy Thursday, Good Friday, Holy Saturday, the Feast of the Ascension...
date for Easter began in Early Christianity as early as the 2nd century AD. Discussion and disagreement over the best method of computing the dateof...
nominal 21 March date. This date was important to the Christian churches because it is fundamental to the calculation of the dateofEaster. To reinstate...
announced the date on which Easter was to be celebrated. The council chose Alexandria because of its famous school of astronomy, and the dateofEaster depends...
As a result, 21 March (which is the base date for calculating the dateofEaster) gradually moved out of alignment with the March equinox. While Hipparchus...
earlier. Since the dateofEaster is calculated differently by Eastern and Western Christians, the dateof the Western Churches' Easter Friday is often different...
"Judaized" (i.e. Passover date for) Easter. The dateof observance ofEaster has only differed in modern times since the promulgation of the Gregorian calendar...
Sunday – date variable Easter Monday – date variable Easter Tuesday – date variable Labour Day – 1 May Pentecost Monday – date variable Dormition of the Theotokos...
The Easter cycle is the sequence of the seasons and days in the Christian liturgical year which are pegged to the dateofEaster, either before or after...
provide a special liturgy for this holy celebration. Since its date depends on the dateofEaster, Pentecost is a "moveable feast". The Monday after Pentecost...
Coptic dateofEaster is determined by a calculation based on the Alexandrian 19-year cycle, which synchronises the lunar months with the solar years of the...
the separation of the dateofEaster from the Jewish Passover (see also Quartodecimanism), stating in his letter after the First Council of Nicaea (which...
moon is on Sunday, Easter is the following Sunday. Thus the earliest possible dateofEaster is March 22, while the latest possible date is April 25. In...
Christianity is the calculation of the dateofEaster (see Computus). Most years, the Eastern Pascha falls after the Western Easter, and it may be as much as...
after the Great and Holy Feast of Pascha (Easter). Since the dateof Pascha changes each year, the dateof the Feast of the Ascension changes. The Feast...
seven of these eight days are also collectively known as Easter Week. Easter Sunday Easter Monday Easter Tuesday Easter Wednesday Easter Thursday Easter Friday...
Day: Christmas, Easter-eve, 25 March (Lady Day). Other countries in Eastern Orthodoxy eventually adopted Gregorian (or New Style) dating for their civil...
and Western Christianity disagree over the computation of the dateofEaster and therefore of Good Friday. Good Friday is a widely instituted legal holiday...
by the dateofEaster. In the Catholic Church, it is the Memorial of the Blessed Virgin Mary, Mother of the Church, marking the resumption of Ordinary...
system for determining the datingofEaster, a style of monastic tonsure, a unique system of penance, and the popularity of going into "exile for Christ"...
uniform observance of the dateofEaster, and promulgation of early canon law. The First Council of Nicaea was the first ecumenical council of the church. Nicaea...
Easter Island (Spanish: Isla de Pascua [ˈisla ðe ˈpaskwa]; Rapa Nui: Rapa Nui) is an island and special territory of Chile in the southeastern Pacific...