Why does the date change for Easter? Does it have something to do with the phase changes of the moon?



The usual statement, that Easter Day is the first Sunday after the full moon that occurs next after the vernal equinox, is not a precise statement of the actual ecclesiastical rules. The full moon involved is not the astronomical Full Moon but an ecclesiastical moon (determined from tables) that keeps, more or less, in step with the astronomical Moon.

The ecclesiastical rules are:
*]Easter falls on the first Sunday following the first ecclesiastical full moon that occurs on or after the day of the vernal equinox;
*]this particular ecclesiastical full moon is the 14th day of a tabular lunation (new moon); and
*]the vernal equinox is fixed as March 21.


And this convoluted calculation came from the date of Passover, modified.

At one point, the Church reasoned that Easter should fall the day after Passover, as that’s how it really happened. However, that would imply that Easter fell on any day of the week. So there was a decision to move to this approach for the date, which maintains a relationship with Passover.

(I think this explanation is correct, I am stating it from foggy memory!)


[quote=DEESYPAL]Why does the date change for Easter? Does it have something to do with the phase changes of the moon?

Perhaps Catholics should realise just how old the equable 24 hour day is for without it you cannot construct a calendar system based on 365.25 days.

Contemporaries begin with with an annual value as if it were found on a piece of paper underneath a rock and do not engage in discussing the foundations of the equable day from the natural unequal day but simply divide the number of rotations of the Earth to come up with an average value which is neither good nor right.


In other words we are the most primitive people ever to set foot on the planet in matters requiring a solid appreceation of how clocks,astronomy,geometry and Christian festivals are a exquisite facet of our Christian heritage.

It is Holy Thursday and this year I will value my Catholic community more than ever in celebrating Christ and His Life.I will also keep in mind the heritage of our ancestors in giving us subtle and intricate astronomical insights which were sorted and sifted for exquisite ends but have lately been abused and misused.

I really wish Catholics could see just how important the loss was in creating an error in principle in astronomical time reckoning.

That wonderful Easter feeling takes precedence for now and I wish you all the best for this coming celebration this weekend.


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