5 April 2009 | Fr Patrick Jones explains how the date of Easter is calculated

02 Apr 2009


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Fr Patrick Jones, Director, National Centre for Liturgy, answers some frequently asked questions about the dates of Easter

Q How is the date of Easter calculated?
A Easter Sunday is the first Sunday after the full moon which occurs after the spring equinox.  The spring equinox is dated 21 March, an ecclesiastical dating but fairly accurate from an astronomical point of view.  The first full moon after 21 March this year is 9 April and this gives us Sunday, 12 April as Easter Sunday.
It is nice to think that our date depends on cosmic factors, on what our Creator gave us, even if Easter can fall as early as 22 March and as late as 25 April, thirty-four days later.   Last year we had Easter on 23 March and in a few years time, we will have a very late Easter, 24 April 2011. 

The history of the date of Easter shows several disputes about its calculation.  In the second century, we find places observing Easter according to the date of Passover, 14th day of the Hebrew month of Nisan, that is, at the first full moon after the spring equinox.  Easter could, therefore, fall on a weekday.  Most, and very soon, all celebrated Easter on Sunday, following the Gospel accounts of the Resurrection.

There remained differences until the Council of Nicea in 325 gave us our present way of calculation.    But different calendars could give different results.  Such a difference existed in these islands until the Council of Whitby in 664 brought us into line with Rome!

Q Why is there a different date for the Orthodox Easter?

A The Julian calendar