Why is Easter moveable?
The date of Easter changes each year (it's a “moveable” feast) without seeming rhyme or reason. It can be as early as March 22 or late as April 25!
The explanation for this dates back to the earliest centuries of the Church. Though Easter is our earliest feast, there was much controversy on when it was to be celebrated.
The Quartodecimans (literally, the fourteen-ers) argued that Easter should be on the 14th of the Jewish month of Nisan each year since that was the date on which Jesus died according to the Gospel of John. The original focus of Easter was on Jesus’s death rather than his resurrection and so the Quartodeciman position made sense.
Others argued that Easter should be celebrated on the Sunday nearest to the Jewish Passover since the relationship between Jesus’s death and resurrection was fulfillment of the Passover story. For those who argued that the holiday’s focus should be on the resurrection, a Sunday observance was in keeping with remembrance that Jesus rose on the first day of the week.
Ultimately, something akin to this latter opinion won out.
At the council of Nicaea in 325 AD, the Easter celebration was “fixed” on the first Sunday after the first full moon after the vernal (spring) equinox on March 21. If this seems strangely complicated, that’s because it is.
The Jewish year was (and still, for religious purposes, is) based on the lunar cycle. Passover was to take place in the seventh month (Nisan) as measured by full moon cycles. So when the date of Easter was “fixed,” it had to be so based on the Jewish lunar calendar. Easter is often, though not always, the Sunday after Passover. (See note below to get really deep in the weeds on this!)
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An aside for anyone who really wants to nerd out about the constructs of time and calendars:
There’s a full moon once every 29.5 days which means that the Jewish year is only 354 days. This is twelve days short of the solar calendar which fixes a year’s length at 365.2425 days. While the solar calendar corrects for those decimal points by adding a day to February every four years (a leap year), lunar calendars must add a month to their year seven times in every 19 year cycle.
In the third century, it was determined that for every 19 year cycle, a month would be added between the sixth and seventh months of the Jewish year (Adar and Nisan, the added month is called Adar II) during the third, sixth, eighth, 11th, 14th, 17th, and 19th years.
According to Benjamin Dreyfus – a physics professor at George Mason University – in an interview with The Atlantic: “The Jewish calendar drifts about one day later every 200 years, and so far there isn’t any mechanism to correct that…in about 6,000 years [Easter and Passover will] be fully out of sync if nothing is done to correct the Jewish calendar. But right now there’s nobody who has the authority to do that for the Jewish world. There’s no pope or anything.”
Read the full Atlantic piece.
