A Moveable Feast -- March 20, 2019

This was really, really cool.

Last night, while driving the middle granddaughter to her soccer practice, I had an opportunity (which I took) to explain to her how the "Easter date" is determined.

We were driving west, directly in front of us, the full moon. And it was huge.

So, today is the spring equinox. [equi = equal; nox = night: night will be equal length in duration as day]

Last night/today: a full moon.

So, Easter:

• the first Sunday, after
• the first full moon, after
• the spring equinox

So, the church looked at the solar calendar to determine the spring equinox, easy-peasy. March 20. Every year. At least in modern times.

Then they pull out the lunar calendar to find the first full moon after March 20 ("on" March 20 is not after March 20) and this year, the lunar calendar shows that the next full moon will be Friday, April 19th, easy-peasy. [March 20 or March 21? See below.]

Therefore, two days later, Easter will fall on Sunday, April 21, 2019. Easy-peasy.

The next question, of course, is how did the "first Sunday after the first full moon after the spring equinox" come into being?

First, one clarification: the Easter date is set in relation to the March Equinox. However, the church counts March 21 as the equinox date in the ecclesiastical calendar, rather than the actual date, which varies between March 19, 20, and 21.

Now, how did "they" come up with the first Sunday after ...? From this link:

According to the Bible, Jesus Christ's 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.

Technically, that last part is unnecessary or redundant, that part about "Easter is delayed one week...." The Council said the first Sunday after the full moon.... although I can see why this might have caused confusion -- but enough for now .. this dead horse has been whipped enough ...

Aha, a reader asks ... how did the Jews come to celebrate Passover related to the lunar calendar? It's a long, long story but suffice to say this: it's based on the Samaritan calendar, and calculation of the Samaritan calendar has historically been a secret reserved to the priestly family alone -- at this link.

Perhaps more at this link, which will provide an etymology for "Easter."