The first Council of Nicaea (year 325) established that the solemnity of the Easter of Resurrection would be celebrated on the Sunday following the first full moon (fourteenth day of the ecclesiastical moon) which comes after the vernal equinox. On that occasion (or, more probably, in the following decades) the official date of the equinox was moved from March 25 to March 21, because, due to the inaccuracies of the Julian calendar, almost four days behind Julius Caesar's time. (However, it must be said that, for various reasons, the exact astronomical date of the equinox varies from year to year and over the centuries). For this reason, the Easter date is between March 22 and April 25 (included). In fact, if March 21 is full moon, and this day is Saturday, it will be Easter the day after (March 22); if instead it is Sunday, Easter day will be the following Sunday (March 28). On the other hand, if the full moon occurs on March 20, the next one will occur on April 18, and if this day were by chance a Sunday, it would be necessary to wait for the following Sunday, i.e. April 25. The question of the method of calculating the date of Easter was much debated within the Church, especially before, but also after the Council of Nicaea.









ATTENTION!
The original page from which this derives is taken from the site on Eugenio SONGIA's calendars.
Click below for the original page:



  The calendar