WEATHER U: Easter conflict between astronomers and the Church

Dawn in Main-à-Dieu. You'll find the tiny fishing village in the Cape Breton Regional Municipality. It is the most easterly community in Nova Scotia. - Contributed

Mom always said the day was not lost if you learned something new.

Last week I learned something very interesting about Easter.

Just before Lent, I wrote about Easter and how it is known as a moveable feast because it doesn’t fall on a set date every year. Easter is always the first Sunday following the first full moon after the spring equinox. Simple enough… or is it?

I was off the day of the equinox, but I noticed a question on my Facebook page from Marilee Lyons

“Why isn’t Easter on March 24? It is, after all, the first Sunday after the first full moon of spring!”

I thought that was a great question and immediately assumed that the official full moon time must have come before the time of the vernal equinox. I didn’t bother checking right away but something didn’t seem right, so before I went to bed that night I looked into it.

The equinox occurred at 6:58 p.m. ADT (7:28 p.m. NDT). The official time of the full moon was 10:43 p.m. ADT (11:13 p.m. NDT).

So, the “full sap moon” was the first full moon after the spring equinox and March 24 was the first Sunday following the full moon. So why wasn’t Easter on March 24?

I snooped around and found something I didn’t know existed: ecclesiastical spring.

From the ecclesiastical perspective, the first day of spring falls on March 21. March 21 was selected as the ecclesiastical vernal equinox because the Church of Alexandria, whose staff was reputed to have astronomical expertise, said that March 21 was the date of the equinox in 325 A.D.

But the date of spring differs in astronomy. In our lifetimes, for the longitudes of North America, spring won’t arrive on March 21 until the year 2102.

This year, since our March full moon falls on the 20th and not the 21st, it is not recognized as the Paschal or “ecclesiastical moon” by the Church. So, we must wait until the next full moon, on April 19. That day is also Good Friday and that evening is the first night of the Jewish feast of Passover. Finally, on Sunday, April 21, we will celebrate Easter. That’s within four days of the latest possible date for this moveable holiday.