King Oswy, Pope Gregory and the Date of Easter

Posted in Blog, Easter

Easter Sunday is late this year – Sunday 17 April. For it to come any later than it was in 2019 (21 April) you’ll have to wait until 2038 (when I shall be 93, God willing). Why does the date of Easter move about so much?

Easter is always on the first Sunday after the first full moon that follows the spring equinox. For the purpose of calculating Easter, the spring equinox is always on 21 March. So in 2022 the first full moon after the 21 March is Saturday 16 April, hence Easter is on Sunday 17 April.

These rules also mean that the earliest possible date that Easter Sunday can fall is the 22nd March. The last time that happened was in 1818. Easter marks the date of Jesus’s death and resurrection, which, the Bible tells us, happened around the Jewish Passover. Like the date of Passover, the date to mark the resurrection was calculated using the lunar calendar, which is based on the cycles of the moon. This complicated matters since at that time lunar cycles were calculated in various ways.

Moreover, different Christian groups disagreed on the date to celebrate the resurrection. Some celebrated it on Passover itself, some the following Sunday. This made things quite complicated. In 325 AD, Emperor Constantine called the Council of Nicaea, the first council of the Christian Church. As well as discussing other key beliefs, the Council wanted to settle the issue of the date of Easter. It was decided that all Christians should celebrate Easter on the first Sunday after the first full moon on or after the spring equinox.

However different traditions kept calculating it in different ways, backing up their choice with different Gospels. In England, Irish monks forcefully argued that their way of doing it had started with John the Evangelist and author of the fourth gospel. But Roman monks claimed their calculations had begun with St Peter himself.

This brings us to the Northumbrian King Oswy who followed the Irish tradition and celebrated Easter at different times from his Kentish wife, who followed the Roman tradition. That was awkward. So in 664 Oswy summoned the Synod of Whitby, a meeting of the clergy who met in Whitby Abbey to sort the matter out. King Oswy had the final say and decided the Roman tradition should be adopted in the whole of England. Apart from wanting to celebrate at the same time as his wife (and wanting to be more politically aligned with Europe), King Oswy’s decision came down to his strong belief that St Peter is the gatekeeper of heaven. So, the Roman tradition was adopted in England. Bishop Coleman of the Irish monks was furious, resigned, and went back to Ireland with a group of like-minded monks, never to return.

At the end of the 16th century, things changed again. Christians had, up to this point, followed the Julian calendar (named after its inventor Julius Caesar). In this system, there is a repeating pattern of three years of 365 days followed by a leap year of 366 days. However, this calendar overestimated the length of the tropical year, the time from one equinox to the next, which also affected the date of Easter. To solve this, in 1582, Pope Gregory XIII suggested deleting a few days from the calendar and adjusting the frequency of leap years. That year, in all countries who went with the Pope’s plan, 4 October was to be followed by 15 October. But, by that point, since England was a Protestant country, the change suggested by the Pope proved to be controversial and wasn’t implemented.

In the 18th Century, Parliament decided that Britain should come into line and that Wednesday 2nd September would be followed immediately by Thursday 14th, and from then on England, Scotland, Wales and Ireland would follow the same calendar as most of Europe. Today, the Gregorian calendar is still not used by all churches. The Orthodox Church follows the Julian calendar, so the Orthodox Easter normally falls a bit later (in 2022 it will be marked on Sunday 24 April.) You will be pleased to hear that, in 2025, both Churches will celebrate Easter on Sunday 20 April.