Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!bcm!dimacs.rutgers.edu!aramis.rutgers.edu!athos.rutgers.edu!christian From: cc433336@longs.lance.colostate.edu (Constantinos A. Caroutas) Newsgroups: soc.religion.christian Subject: Reasoning for Determining the Date of Easter Sunday Message-ID: Date: 3 Feb 91 04:29:55 GMT Sender: hedrick@athos.rutgers.edu Organization: Colorado State University, Fort Collins, CO 80523 Lines: 105 Approved: christian@aramis.rutgers.edu As you know, Christ was crucified in the week of the Jewish Passover and resurrected on the Saturday of the Jewish Passover. At the Ecumenical Synod of 325 in Nice, Asia Minor, the bishops decided when to celEbrate Easter. Having in mind the events, they decided to celebrate on the Sunday after the Saturday on which the Jewish Passover occurs. That is, right after the Passover. But, when is the Saturday of the Jewish Passover? The Jews use a lunar calendar for their religious purposes. There is, however, an equivalent for this case in the Julian calendar. The Saturday of the Jewish Passover is the first on or after the first full moon after 20 March (of the Julian Calendar). Please note that the Julian calendar is currently 13 days behind the Gregorian calendar (which we currently use). That is, 1 February 1991 GC = 19 January 1991 JC. According to the Julian calendar, every year that is divisible by 4 is leap. According to the Gregorian calendar, every year divisible by 4 is leap unless it is divisible by 100; in that case, it has to be divisible by 400 to be leap. Anyway, the bishops at the Synod of 325 agreed on a calculation to determine the date of the full moon in question. Then the Easter Sunday would be the first one after that full moon. I present the calculation below: 1. Take the year, divide it by 19 and take the remainder. If the remainder is 0 make it 19. 2. Take the remainder found above, multiply it by 19, add 15, and then divide by 30 and take the remainder. 3. Add that remainder found in step 2 to 21 March. That is the date of the full moon in interest. The first Sunday after it is the Easter Sunday. The above is for the Julian calendar. Add the difference between it and the Gregorian calendar (currently 13 days) to 21 March to convert to Gregorian calendar. While the calculation above is quite accurate, it is not exact. After 16 centuries it overshoots the full moon date by 4-5 days. So usually, Easter Sunday is not one day after the Saturday of the Jewish Passover, but eight. The calculation going off (about 1 day every 400 years) is not the only problem. Earth takes 365 days 5 hours and almost 49 minutes to go once around the sun. The 5:49 hours add up to almost 97 days in 400 years. So, with the Julian calendar having 100 leap years every 400 years, it meant that the seasons were shifting. A pope by the name Gregory whose hobby was astronomy found that and proposed a new calendar to fix that. The Orthodox, of course, did not accept it. It is as I have decribed above. Plus, since it is not exact, astronomers will have to make adjustments [a day added or subtracted (I'm not sure)] every several thousand years. Pope Gregory also realized that the Jewish Passover was moving toward the summer. It was not a feast of the spring. Adding to the shift in the calculation for the Easter, it meant that the Easter was moving toward the summer at the average rate of 1 day every century. And, once at summer, it would not stay there. It would keep moving forward. Switching to the new calendar meant that something had to be done to keep Easter in spring. So, pope Gregory decided to have Easter on the first Sunday after the first full moon after 20 March. Since he did not have the authority to make that change, the Orthodox church did not accept it. Only the Ecumenical Synod has the authority to make that change. So, the Orthodox Easter is found on the Julian calendar and then that date is converted to the Gregorian calendar. Considering the above, the Orthodox Easter currently occurs on the same date as the Western, or 4 weeks later, or 1 week later, or 5 weeks later. When the difference is 0 or 4 weeks, then the Orthodox Easter Sunday is right after the Saturday of the Jewish Passover. I hope it all makes sense now. Leap seconds. The Earth is slowing down and thus the average solar day is a bit more than 24:00:00 hours now. Every few years, the difference adds up to 1 second which is added at the last moment of a year. Orthodox using Julian or Gregorian calendar: In countries where an Orthodox church has a "good relationship" with the state the church uses the Gregorian calendar. Otherwise, it uses the Julian calendar. For example, the Russian Orthodox church uses the Julian calendar, while the Orthodox church of America --established by the Russian Orthodox church-- uses the Gregorian calendar. The Ecumenical Synod has the right to change the church calendar, but we cannot have one until the churches unite. Since the Gregorian calendar has the same objective as the Julian calendar -the Gregorian calendar is simply more accurate-- it is certain that an Ecumenical Synod would approve it. So, some churches adopted it for the sake of convenience. It is quite disappointing that some stick to the Julian calendar. I believe that if the curches unite, they'll all adopt pope Gregory's way to determine the Easter date. And, that is certainly the least of the differences between the churches. -- Constantinos A. Caroutas _______________________________________________________________________________ "People tell me I can't have everything | from "On The Way Up" But still I want to have it all | Elisa Fiorillo I'm on the way up; look out" | I AM (1990) _______________________________________________________________________________