It just makes eminent sense to adopt the spirit of the Council of Nicaea and adopt the calendar that is in use today as the basis for calculating Pascha. If there are those churches that refuse, so be it. Let them carry on their "Third Rome" pretense. Does any one care anymore?
Prior to composing this post I thought about that, who cares, especially with all the troubles of the world. Yet the churches have struggled with this issue, documented since at least the mid-second century AD Quartodeciman controversy. And as this thread witnesses, the WCC and an Orthodox Church and member in particular, have brought it to our attention again.
Also, we are the victim of circumstance; it turns out that there recently occurred everywhere throughout the whole world, and at the very same instant, an event relevant to this discussion: the northern hemisphere vernal (spring) equinox. This is a primary event used for timing and so the correct question is not When did it occur?
but What was your particular timing device indicating when it happened?
. For my time zone and clock, for instance, it happened yesterday 20-March-2022 on the civil calendar at 11:33 am Eastern Daylight Time (An informative article that has other details is When does spring 2022 start?
The calendar and methods for timing Pesach/Passover and Pascha have gone through phases that I would classify as:
(1) Observational: OT to early NT times
(2) Computus using averages (Pascahalion): Nicaea (4th c) to present
(3) Modern detailed scientific, astronomical: 20-21st c.
Using detailed discrete calculations had been considered during the Gregorian reform. They were initially favored by Clavius, its chief architect, but the traditional computus approach was adopted.
The latest proposal, initiated by some Orthodox in the early 20th c., favored by Aleppo (1997) and repeated by +JOB (2021) is that scientific, astronomical approach:
It is worth mentioning that in 1997, the World Council of Churches held a consultation in order to establish a common date for Easter and recommended maintaining the Nicene norms (that Easter should fall on the Sunday following the first full moon of spring), to calculate the astronomical data (the spring equinox and the full moon) by the most accurate possible scientific means, using as the basis for reckoning the meridian of Jerusalem, the place of Christ’s death and resurrection.
(e) The Council of Nicea also has an enduring lesson for Christians today in its willingness make use of contemporary science in calculating the date of Easter. While the council sought to advance the concrete unity of the churches, it did not itself undertake a detailed regulation of the Easter calculation. Instead it expected the churches to employ the most exact science of the day for calculating the necessary astronomical data (the March equinox and the full moon).
(b) to calculate the astronomical data (the vernal equinox and the full moon) by the most accurate possible scientific means,...
Those proposals, while basically sound, need to be explored further, especially in relation to the other phases, (1) and (2) above. The stated standard of using "the most accurate possible scientific means" requires dealing with the science, and that means attention to details and astronomical concepts. For instance, is giving the EDT occurrence as 11:33 sufficiently precise? Hours and minutes are given but what about seconds and hundredths of a second etc. Terms -- accurate, precise, error -- are used with a common, colloquial meaning and understanding that can be misleading. How is the venal equinox defined, determined, calculated? How has the statement of the rule for determining Passover/Pascha(Easter) changed and how true is that statement to the source, the scriptural texts?
To put yesterday's event into context, both the Gregorian and Julian calendars were designed so that the vernal equinox is intended to occur on its respective 21-March. The astronomical vernal equinox occurred:
20-March-2022 on the Gregorian calendar
07-March-2022 on the Julian calendar