This year the Orthodox and Catholic Easters coincide on the same date, at 20 April. But why does the date of Easter move and what is the historical connection?……
between the astronomical calculations and the determination of its date by the Christian churches in the East and in the West;
As reported by AMPE, in a related article, the Jews, based on the lunar calendar they used which was based on the cycle of the Moon, the so-called "synodic month", they celebrated Passover - from the Hebrew word "pesach" meaning "passover" (Red Sea)- the 14th of the month Nisan, which was the day of the first spring full moon, which takes place on or just after the vernal equinox.
However, because Christ was resurrected on the first day after the Jewish Passover, the vernal equinox was associated with the celebration of the Christian "new" (new) Easter commemorating His "passing from death to life".
During the first three centuries of Christianity, the various local churches celebrated Easter on different dates. The Judaizing churches (mainly Asia Minor) it was celebrated on the day of Christ's death on the 15th of the Jewish month of Nisan (on any day of the week fell), while other churches (mainly the national ones) on the first Sunday - as resurrection day- after the first spring full moon.
Because of their differences and disagreements, the A’ Ecumenical Council in Nice, which was convened by Constantine the Great 325 A.D., decided that Easter should be celebrated on the first Sunday, after the first spring full moon and if the full moon occurs on a Sunday, then to be celebrated on the following Sunday.
Cat’ this way, the Christian Easter would never coincide with the Jewish one, while the celebration of the Christian Easter was officially linked to an astronomical phenomenon, the vernal equinox and the first full moon of spring (the so-called "Easter full moon").
A’ The Ecumenical Synod assigned the respective Patriarch of Alexandria to notify the other churches each year of the day of Easter, since it had previously been calculated -with the help of the reputable astronomers of Alexandria- the date of the first spring full moon. consequently, to calculate the date of Easter one year, it was enough to know the date of the first spring full moon and, subsequently, to find the first Sunday after this full moon.
The calendar that was valid at the time of A’ Ecumenical Council, Julian was that Julius Caesar had adopted the 45 e.g., with the help of the Greek Alexandrian astronomer Sosigenis. The Last, based on the calculations of the "father" of astronomy 'Hipparchus (who a century ago had calculated with marvelous accuracy that the solar year has a duration 365,242 days), established a calendar, whose years had 365 days, while every fourth year (the dividing line) add one more day.
Two errors
Nevertheless, according to Dionysis Simopoulo, director of the Planetarium of the Eugenides Foundation, the Julian Calendar had some flaws, because there was still a slight deviation, given that the length of the solar year actually is 365,242199 days. So, the year determined by Sosigenis is greater than the actual year 11 minutes and 13 seconds
Every four years, this little mistake happens approx 45 minutes and every 129 years arrive in one day, with the consequence that the vernal equinox is continually moved forward. The 1572, when Gregory XIII was elected pope, instructs astronomers Christopher Clavius and Luigi Lilio to launch calendar reform, which was published on 1582.
The October 5 1582 it was called October 15th, to correct the error of ten days, that had accumulated during the previous ones 11 centuries, so the vernal equinox to return on March 21st, as it was during A’ Ecumenical Council.
The New or Gregorian Calendar was accepted by the Catholic states of Europe within the next five years, while the Protestant states delayed much longer. In the East the reaction of the Orthodox Church to the Gregorian Calendar was even more intense and thus the Julian Calendar remained in force in all Orthodox states until the 20th century.
The Greek government moved the calendar issue on 1919 and 1923, the Julian Calendar was replaced by the Gregorian, with the start of its implementation on 16 February 1923, which was named March 1st. They removed that 13 days from 1923, for in the ten days of error between Gregorian and Julian from the 325 A.D. to 1582, the delay of another three days had been added to the approx 340 years that had passed since the Gregorian Calendar was first introduced in the West.
Initially our Church kept the Julian Calendar, however -to avoid confusion- he accepted, the 1924, the ecclesiastical calendar to be aligned with the political calendar and to be valid for fixed holidays. But on the other hand, did not make a parallel change of the Easter calendar and the mobile holidays (almost a third of the calendar), which in our country are still being calculated, until today, based on the Julian or Old Calendar.
According to Mr. Simopoulos, the difference in the celebration of Easter between the Western and Eastern churches is not only based on the error of the Julian Calendar, but also to -also incomplete- "Metonic Circle" (of the 5th century BC), still used by the Christian Alexandrian astronomers and on the basis of which the Orthodox Church still calculates the dates of future spring full moons.
According to the lunar cycle of the Athenian astronomer Metonos (432 e.g.), 19 tropical-solar years (the time interval between two consecutive vernal equinoxes) is approximately equal to 235 lunar synodic months, that is, it is supposed that after the lapse 19 years the dates of the full moons repeat, but something that is not completely accurate.
The period of 235 lunar months is not exactly equal to 19 years, but greater against 0,086399 days or 2 hours, 4 minutes and 24,8736 seconds in each 19-year cycle. Over the years, these mistakes have accumulated and so, at 13 days to incorrect Juliana vernal equinox, the error of the 19-year Metonic cycle is now added, which amounts, from 325 A.D. until today, in about four to five days, thus identifying Metonia (or Julian) full moon four to five days later than the actual one.
The Greek Orthodox Church still uses the old Julian Calendar and the Metonic cycle for determining the date of Easter. So, many times, Orthodox Easter is celebrated not on the first Sunday after the full moon, but on the next (as it happened 2012) or even celebrated after the second spring full moon (as it happened 2002 and 2013), instead of the first Sunday after the first spring full moon, as set by the Council of Nicaea.
As reported by AMPE, according to the mathematician and diarist Dimitris Bounakis, in the current 21st century the limits of celebrating the Orthodox Easter are from 4 April (the earliest) until 8 May (at the latest). The old calendarists have Easter in common with the rest of the Orthodox (of the new calendar), but dated 13 days less (until 2099), so this year's Easter was celebrated on 7 April.
Jointly celebrated Easter for Catholics and Orthodox, when both the Gregorian, as well as the Julian-Metoneia Easter full moon fall from Sunday to Saturday of the same week, so the next Sunday is the common Easter.
This is exactly what is happening 2014, as this year the Gregorian Easter full moon falls on 14 April and Julian-Metoneia on 18 April, while the actual astronomical full moon is at 15 April.
The celebration and the years will be common 2017 (at 16 April), 2025 (20 April), 2028, 2031, 2034, 2037, 2038, 2041, however, the last common Easter is calculated - according to Mr. Bounakis- that will happen in the year 2698, as after 2700 -due to accumulation of error Metoneiou- the Julian and Gregorian full moons can never fall in the same week.
In each case, this difference in the celebration of Easter between the Eastern and Western churches, according to Mr. Simopoulos, it does not concern doctrinal matters of Christian ecclesiastical worship or religion, but an astronomical-mathematical problem.
Source : iefimerida.gr
Diligence : NewsRoom Mykonos Ticker
Diligence : NewsRoom Mykonos Ticker