How the Easter Date is Determined

An Easter Sunday date in the calendar.

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Easter Sunday celebrates the Christian belief of Jesus Christ's resurrection.The Easter date is set around the time of the March Equinox.

Setting the Easter Date

The March equinox coincides with Easter Sunday and holidays that are related to it. These holidays do not fall on a fixed date in the Gregorian calendar, or the Julian calendar, which is still used by many Orthodox Christian churches.

The dates of many Christian holidays depend on the Easter date. Some of these holidays include:

• Palm Sunday
• Good Friday
• Easter Sunday
• Ascension Day
• Pentecost/Whitsunday.

According to the Bible, Jesus’ death and resurrection occurred around the time of the Jewish Passover, which was celebrated on the first full moon following the vernal equinox.

This soon led to Christians celebrating Easter on different dates. At the end of the 2nd century, some churches celebrated Easter on the day of the Passover, while others celebrated it on the following Sunday.

In 325CE the Council of Nicaea established that Easter would be held on the first Sunday after the first full moon occurring on or after the vernal equinox. From that point forward, the Easter date depended on the ecclesiastical approximation of March 21 for the vernal equinox.

Easter is delayed by 1 week if the full moon is on Sunday, which decreases the chances of it falling on the same day as the Jewish Passover. The council’s ruling is contrary to the Quartodecimans, a group of Christians who celebrated Easter on the day of the full moon, 14 days into the month.

Comparative calendars

Not all Christian churches observe Easter according the Gregorian calendar. Some churches still observe Easter under the Julian calendar.

The Gregorian calendar was created because the Julian calendar was slightly too long. With the Julian calendar, the equinox date moved towards the earlier dates of March and further away from the Easter. Therefore, the introduction of the Gregorian calendar allowed for a realignment with the equinox.

According to the Gregorian calendar, Easter falls on a Sunday between March 22 and April 25 from 1753 to 2400. In the Julian calendar, used by some eastern or Orthodox churches, Easter also falls on a Sunday from March 22 to April 25, which in the Gregorian calendar are from April 3 to May 10 from 1753 to 2400.

In 2007 Easter fell on the same date (April 8) in both calendars when the Julian date was converted to the Gregorian date. This happens in some years, such as 2004, 2010 and 2011.

Proposed Easter Date Reforms

There have been a number of suggested reforms for the Easter date. For example, in 1997 the World Council of Churches proposed a reform of the Easter calculation to replace an equation-based method of calculating Easter with direct astronomical observation.

This would have solved the Easter date difference between churches that observe the Gregorian calendar and those that observe the Julian calendar. The reform was proposed to be implemented in 2001, but it is not yet adopted.

Another example of a proposed reform occurred in the United Kingdom, where the Easter Act 1928 was established to allow the Easter date to be fixed as the first Sunday after the second Saturday in April. However, this law was not implemented, although it remains on the UK Statute Law Database.