2012. Updated Nov. 22, 2021
WHAT IS THE EASTER CYCLE?
The Easter Cycle is a chunk of the Roman Catholic (R.C.) Church year centered on Easter. The Sundays in the Easter Cycle either count down to Easter, or use Easter as the beginning of a subsequent count. The date of Easter depends on the date of the Paschal Full Moon, and that date changes from year to year on solar calendars. So, the dates of Easter Cycle feasts also change from year to year on solar calendars. Easter Cycle feasts are for that reason called movable. The Church year also has a non-moving part, namely, the Christmas Cycle, which includes the seasons of Advent, Christmas, Epiphany, and Time after Epiphany. The Christmas Cycle is centered on the date of Christmas Day, Dec. 25. In solar calendars, that is a fixed date.
The Christmas Cycle and the Easter Cycle together span one entire year. The Easter Cycle shifts its position from year to year, causing changes to the beginning and end of the Christmas Cycle.
WHAT IS THE PASCHAL MOON, AND WHY USE IT?
Circa AD 30, Our Lord was crucified on the eve of a Sabbath day, on the first day of a Passover, and on the day of a full Moon. His Resurrection was then on the first day of the week after the Sabbath, still during the days of Passover, and after a full Moon. The early Church desired to keep those specific attributes in connection with the observance of the Feast of the Resurrection, and today’s Church still endeavors to do so. Easter was traditionally observed either on Passover, or on the Sunday after Passover. And the date of Passover is determined partly by lunations, not strictly by a solar calendar. According to the USNO, the date of Passover is determined by the Jewish calendar, which is lunisolar (That info was from the USNO Date of Passover page, which is currently, “404 Not Found”). The R.C. Church no longer follows the Jewish calendar, but uses a solar calendar (the Gregorian), and calculates the date of the Paschal (or Passover) Moon differently. According to the USNO, the R.C. Church defines the Paschal Moon to be the first full Moon on or after March 21, and full is defined as the 14th day of the new moon. The date of Easter is the first Sunday after the Paschal Full Moon.
In some years, the Jewish Passover Moon varies by one lunation from the R.C. Paschal Moon. And either of those may vary from the Julian calendar’s Paschal Moon (which some Churches still use). However, all these full Moons occur near the vernal equinox. And the Moon is not full on the same dates year after year. The lunar year consists of 12 lunations (or 354.37 mean solar days). The solar year consists of about 365.25 mean solar days. So, when an event depending on the date of a full Moon is placed in a solar calendar, it cannot occur on the same solar date from year to year. That is why (from the Gregorian calendar frame of reference) the date of the Jewish Passover changes from year to year, as does the date of Easter. Now let’s consider the movement of the date of Easter relative to the lunar calendar.
March 21 is an earth orbit (solar calendar) event, not a lunar orbit event. Thus, the ecclesial calendar’s Paschal Moon is not just one lunar calendar Moon. As soon as the Paschal Moon in use slips too far away from the solar calendar date of March 21, the calendar drops that Moon, and uses the next Moon in the lunar year for the Paschal Full Moon. If the Paschal Moon did not change like that, that is, if Easter was affixed or pegged to just one lunar calendar Moon, then the Easter Cycle would crash its way through the fixed dates and observances of the entire solar year. It would do that in Metonic (19 year) cycles. Defining the Paschal Full Moon to be the first full moon on or after March 21 limits the shifting of the date of Easter to a maximum of the 34 days between March 22 and April 25 (That info was from the USNO Date of Easter page, which is currently, “404 Not Found”).
The use of a Paschal Moon is important, not just because the ecclesial calendar thus preserves the connection of the Resurrection to Passover, but also because each full Moon is a counter; the count of full Moons since the Crucifixion serves as a valid and accurate reckoning of New Covenant times. These began not with the birth of Jesus, but with His institution of the Holy Eucharist and His Crucifixion. The world’s scholars do not know the exact year of Christ’s Crucifixion. Thus they do not know the exact lunation count. That ignorance, however, is because of the negligence of men. The Moon has been keeping time faithfully over the millennia. And God is able to reveal to someone the number of lunations since the Crucifixion. From that, the AD and the solar month of the Crucifixion could be accurately calculated.
The R.C. Church implemented the Gregorian calendar Oct 15, AD 1582, but the calendar was accepted by different nations and cities at different times. Some Eastern Churches still use the Julian calendar. So, all times before Oct 15, 1582 are pre-Gregorian times. However, for years 1582 or greater, some nations, cities, and Churches use Gregorian, and some do not. To determine whether a given year is Gregorian for a given place, consult the chart below:
PLACE FIRST GREGORIAN DATE (year, mo, da) Albania 1912, 12, ?? Augsburg 1583, 02, 24 Baden 1583, 11, 27 Bavaria 1583, 10, 16 Belgium (Did not exist. Use Netherlands.) Bohemia 1584, 01, 17 British Colonies 1752, 09, 14 Bulgaria 1915, 11, 14 or 1916-04-14? Carynthia 1583, 12, 25 China 1949 Cologne 1583, 11, 14 or 1583-11-13? Czech Republic: (Did not exist. Use Bohemia and Moravia.) Denmark 1700, 03, 01 Estonia 1918, 02, 14 Egypt 1875, ??, ?? Faeror 1700, 11, 28 or 1700-11-27? France 1582, 12, 20 Alsace 1682, 02, 16 Lorraine 1760, 02, 28 Strasbourg 1682, 02, 16 Strasbrg. diocese 1583, 11, 27 Finland (Did not exist. Use Sweden.) Germany Protestant 1700, 03, 01 Great Britain 1752, 09, 14 Ireland 1752, 09, 14 Scotland 1752, 09, 14 Wales 1752, 09, 14 Greece 1924, 03, 23 Hildesheim 1631, 03, 26 Holland 1583, 01, 01 or 1583-1-12? Hungary 1587, 11, 01 Iceland 1700, 11, 28 Italy 1582, 10, 15 Japan 1873, 01, 01 Julich 1583, 11, 13 Latvia 1918, 02, 15 Liege 1583, 02, 21 Lithuania 1915, ??, ?? Luxembourg 1582, 12, 25 Mainz 1583, 11, 22 Minden 1668, 02, 12 Moravia 1584, 01, 17 Netherlands Drente 1701, 05, 12 or 1701-01-12? Friesland 1701, 01, 12 or 1701-01-13? Holland 1583, 01, 12 Gelderland 1700, 07, 12 Limburg & southern provinces (now Belgium) 1582, 12, 31 Staten Generaal 1582, 12, 25 Utrecht 1700, 12, 12 Zeeland, Brabrant 1582, 12, 25 Norway (Did not exist. Use Denmark.) Paderborn 1585, 06, 27 Portugal 1582, 10, 15 Poland 1582, 10, 15 Prussia 1610, 09, 02 Romania 1919, 04, 14 or 1924-10-14? Russia 1918, 02, 14 Silesia 1584, 01, 23 Spain 1582, 10, 15 Treves 1583, 10, 15 Sweden 1753, 03, 01 Switzerland (local variations) Catholic cantons 1583, 1584 or 1597 Protestant cantn. 1701, 01, 12 Lucerne 1584, 01, 22 Zurich 1701, 01, 12 Transylvania 1590, 12, 25 Turkey 1927, 01, 01 Tyrolia 1583, 10, 16 U.S.A. (Did not exist as such.) Alaska 1867, 10, ?? Eastern seaboard: Use Great Britain, 1752 Mississippi valley: Use France, 1582 NW Terr: Use Great Britain, 1752 Southern parts: Use Spain, 1582 Westphalia 1584, 07, 12 Wurzburg 1583, 11, 15 Yugoslavia 1919, ??, ??
I compiled the above chart from: