Easter
Dear All, Those of you who have studied the great noon marks in Italy and elsewhere will know their importance in the reckoning of the date of the Vernal Equinox and, hence, the Date of Easter. This year Easter is unusually early which begs the questions: How unusual? Can it be earlier? Over the 5,700,000-year Easter Cycle, Easter falls on 23 March 54150 times, less than once a century. After this year, Easter will next fall on 23 March in 2160. The earliest date that Easter can fall is 22 March and that is also the rarest date, occurring 27550 times in 5,700,000 years. The next occasion is 2285. The latest date that Easter can fall is 25 April and this occurs 42000 times in 5,700,000 years. The next occasion is 2038. The most common date is 19 April, which occurs 220400 times in 5,700,000 years. The next occasion is 2071. For further details, see the table following my signature. Meanwhile... Happy Palm Sunday Frank King Cambridge, U.K. Here is the distribution of possible dates for Easter over the 5,700,000-year Easter Cycle given the current algorithm for determining the date and given the Gregorian Calendar: Dates Counts 22 March 27550 [Rarest, next time 2285] 23 March 54150 [Next times 2008, 2160] 24 March 81225 25 March 110200 26 March 133000 27 March 165300 28 March 186200 29 March 192850 30 March 189525 31 March 189525 1 April 192850 2 April 186200 3 April 192850 4 April 186200 5 April 192850 6 April 189525 7 April 189525 8 April 192850 9 April 186200 10 April 192850 11 April 186200 12 April 192850 13 April 189525 14 April 189525 15 April 192850 16 April 186200 17 April 192850 18 April 197400 19 April 220400 [Commonest, next time 2071] 20 April 189525 21 April 162450 22 April 137750 23 April 106400 24 April 82650 25 April 42000 [Next time 2038] --- https://lists.uni-koeln.de/mailman/listinfo/sundial
easter
Re the Easter calculation, a simple question from a simple reader. The moon is unconcerned with the solar calendar but in time the Gregorian calendar drifts away from the true equinox. Not by much (an extra leap year will be needed in 4909, I understand) but it matters in 5,7000,000 years. How does the Easter algorithm account for this? Frank 55N 1W -- No virus found in this outgoing message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.21.7/1332 - Release Date: 17/03/2008 10:48 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
easter
For an intriguing algorithm for calculating the date of easter, as proposed by the great German mathematician Gauss, see Fortran Programming by Robert V Jameson, McGraw-Hill, 1966, LCC number 65-27979 32271, page 150. This is the algorithm I used in my Basic language program... I will include the page with the copy of the Basic program to those who requested that program from me off list... John --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Easter
An interesting sidelight to the date of Easter in the early Christian church, and one of the most divisive and contentious subjects, related to the date of Passover. Passover was not as well defined back then. The beginning of each lunar month was declared by a committee appointed by the Sanhedrin based on the physical observation of the first crescent moon. The choice of which lunar month represented the beginning of spring was based on crude observation of such things as the state of vegetation; the astronomical event of the vernal equinox was not a consideration. We will never know whether the Crucifixion was in March or April because no one noted if that year was warm and wet or a cool, dry one. The death of Jesus was originally observed on Nisan 14 and Easter was celebrated three days later (particularly in the east) regardless of the day of the week on which it fell. In the west, Easter was generally (but not always) celebrated on a Sunday . The supporters of the eastern practice became known as quartodecimians due to their adherence to Nisan 14 and the supporters of Easter Sunday became known as quintodecimians. Since the time of Passover was determined empirically, the quartodecimians had to ask Jewish authorities when Passover began in order to know when to celebrate Easter. To many church leaders, the quartodecimians represented an unacceptable dependence on Jewish customs that had to be eliminated (the so called "quartodecimian heresy"). This was a major motivation for the First Council of Nicea (AD 325). The Nicean Council did not define a method for determining the date of Easter but said only that it should be celebrated on Sunday. The practice of using the vernal equinox to define the beginning of spring originated with the bishops of Alexandria (probably using the resources of the great library). The method of using the Metonic cycle to predict when the Paschal moon would occur also originated in Alexandria and this lunar cycle is still known as the "Alexandrine cycle" in church literature. The process of determining the date of Easter was far beyond the capabilities of all but the most learned and the practice of paschal letters from the Pope originated to ensure that all Christians celebrated Easter at the same time. Summary: Discussions concerning the date of Easter are not new. Footnote: Nisan, the month of new grain, is the seventh month of the Jewish year in the current Jewish calendar but it was not always so. According to the Mosaic law, Abib, the month the Israelites came out of Egypt, would be the first month of the year and Passover would be celebrated during Abib. Abib was probably in about April. After the captivity in Babylon, the names of the months were changed to names of Chaldean origin and Nisan became the first month. Also, the civil year was changed to begin at the start of Tishri and Nisan became the seventh month, although Nisan is still the start of the Jewish ecclesiastical year. James E. Morrison Astrolabe web pages at: http://myhouse.com/mc/planet/astrodir/astrolab.htm
Easter
Good friends! (And you are so many, indeed.) You have solved my Easter problem over and over and I am truly grateful. Was there life before the sundial newsgroup? How did we survive? I shall pass on the information to the chap who really needs to know. He is organising shore courses in Scotland for marine biologists and of course wants the best low tides. As I know from my experience in the same game those in the Easter holidays occur near Easter Sunday when students are at home. Why these tides? Because it is the full moon (real or ecclesiastical) which means spring tides. The Church has a lot to answer for. -- Frank Evans
Re: Easter
Dear Frank, Thanks for posting the Easter dates. If you can find the time, this mailing list member (and likely others) would much appreciate details about how you derived the list of dates. Best wishes, Mac Oglesby >Dear All, > >Those of you who have studied the great noon marks in >Italy and elsewhere will know their importance in the >reckoning of the date of the Vernal Equinox and, hence, >the Date of Easter. > >This year Easter is unusually early which begs the >questions: How unusual? Can it be earlier? > >Over the 5,700,000-year Easter Cycle, Easter falls on >23 March 54150 times, less than once a century. After >this year, Easter will next fall on 23 March in 2160. > >The earliest date that Easter can fall is 22 March and >that is also the rarest date, occurring 27550 times in >5,700,000 years. The next occasion is 2285. > >The latest date that Easter can fall is 25 April and >this occurs 42000 times in 5,700,000 years. The next >occasion is 2038. > >The most common date is 19 April, which occurs >220400 times in 5,700,000 years. The next occasion >is 2071. > >For further details, see the table following my >signature. Meanwhile... > >Happy Palm Sunday > >Frank King >Cambridge, U.K. > >Here is the distribution of possible dates for Easter >over the 5,700,000-year Easter Cycle given the current >algorithm for determining the date and given the >Gregorian Calendar: > > Dates Counts > > 22 March 27550 [Rarest, next time 2285] > 23 March 54150 [Next times 2008, 2160] > 24 March 81225 > 25 March 110200 > 26 March 133000 > 27 March 165300 > 28 March 186200 > 29 March 192850 > 30 March 189525 > 31 March 189525 >1 April 192850 >2 April 186200 >3 April 192850 >4 April 186200 >5 April 192850 >6 April 189525 >7 April 189525 >8 April 192850 >9 April 186200 > 10 April 192850 > 11 April 186200 > 12 April 192850 > 13 April 189525 > 14 April 189525 > 15 April 192850 > 16 April 186200 > 17 April 192850 > 18 April 197400 > 19 April 220400 [Commonest, next time 2071] > 20 April 189525 > 21 April 162450 > 22 April 137750 > 23 April 106400 > 24 April 82650 > 25 April 42000 [Next time 2038] > > >--- >https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Easter Algorithm
Mac Oglesby asked how one might begin to calculate the statistics for Easter as recently indicated by Frank. Now, I always thought that the algorithm which applies to any year since the introduction of the Gregorian Calendar, and which in Britain was in September 1752 is as given below. For those uninterested in its programming it can (I believe!) be found as a calculator for any year at: http://www.ely.anglican.org/cgi-bin/easter Whether it's correct I do not know but Frank indicated an Easter Cycle of 5,700,000 years and so to check, I entered the year 5702008. It yields Ash Wednesday 6 February 57002008 Palm Sunday 16 March 57002008 Good Friday 21 March 57002008 Easter Day 23 March 57002008 Ascension Day 1 May 57002008 Pentecost 11 May 57002008 Trinity Sunday 18 May 57002008 Advent Sunday 30 November 57002008 which is, as Frank points out, the same as for 2008, viz: Ash Wednesday 6 February 2008 Palm Sunday 16 March 2008 Good Friday 21 March 2008 Easter Day 23 March 2008 Ascension Day 1 May 2008 Pentecost 11 May 2008 Trinity Sunday 18 May 2008 Advent Sunday 30 November 2008 Patrick ___ Here's the algorithm that I think is used by the calculator: We refer to the year number as y, and use it to calculate the Golden number, g: g = y mod 19 + 1 Next we calculate the date of the Paschal full moon, that is, the full moon which Easter is the Sunday after. This is done in several stages. First we calculate two values called the solar correction, s, and the lunar correction, l. s = (y - 1600) div 100 - (y - 1600) div 400 l = (((y - 1400) div 100) × 8) div 25 Next we calculate an uncorrected date for the Paschal full moon, p'; then we apply a minor correction to get the exact date, p, as the number of days after 21st March. p' = (3 - 11g + s - l) mod 30 if (p' == 29) or (p' == 28 and g > 11) then p = p' - 1 else p = p' Now we need to determine the date of the following Sunday. First we calculate the 'Dominical number', d: d = (y + (y div 4) - (y div 100) + (y div 400)) mod 7 Note that this is the number from which the Dominical letter is determined, and we calculate d', which is the date on which the first Sunday of the year falls: d' = (8 - d) mod 7 We already have p, the date of the Paschal full moon in days after 21st March. Next we determine p'' the first date in the year which falls on the same day of the week as the Paschal full moon. First we determine the 'day number' of p with respect to 1st January. This is 31 + 28 + 21 + p = 80 + p. (Note that we can disregard possible occurences of 29th February, because the calculation of d has already taken this into account, and we shall see that these two values will cancel each other out.) p'' is then given by the formula: p'' = (80 + p) mod 7 = (3 + p) mod 7 The difference between d' (the first Sunday in the year) and p'' (the day of the week when the Paschal full moon falls) gives us the number of days that must be added to p to get the date of the following Sunday, which is Easter Day. There is one further subtlety. This number must lie in the range 1-7, rather than 0-6, since Easter is not allowed to fall on the same day as the Paschal full moon. We first determine x', the difference between d' and p'': x' = d' - p'' = (8 - d) mod 7 - (3 + p) mod 7 = (8 - d - (3 + p)) mod 7 = (5 - d - p)) mod 7 To force this to lie in the range 1-7, we calculate x x = (x' - 1) mod 7 + 1 = (4 - d - p)) mod 7 + 1 We can now calculate e, the number of days Easter falls after 21st March: e = p + x or e = p + 1 + (4 - d - p) mod 7 In other words Easter Day is: if e < 11 then (e + 21) March else (e - 10) April ___- --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Easter
Dear Mac, Many thanks for your message... > If you can find the time, this mailing list member ... > would much appreciate details about how you derived the > list of dates. I am glad you asked this question and equally glad that Patrick Powers has supplied the algorithm! I had it in my head that this algorithm was first published in Butcher's Ecclesiastical Handbook in 1876 and I give this as the (incorrect) citation in one of my sets of student exercises. When I Googled "Butcher's Ecclesiastical Handbook" all I got was a couple of references to plagiarised versions of my exercises. Tee hee! I wouldn't have discovered my error had you not prompted me to look for something else! I first saw the algorithm in Meeus and now see that he gives the correct citation "Butcher's Ecclesiastical Calendar, 1876". There is a reasonably complete account in: http://en.wikipedia.org/wiki/Computus One of my favourite books is "Calendrical Calculations" by Edward M. Reingold and Nachum Dershowitz. It is full of good jokes! This book almost attributes the algorithm to Clavius and Lilius (key figures in the Gregorian reform of the calendar). Once you have implemented the algorithm you can then have fun determining the length of the cycle. A naive approach is to start at an arbitrary year and look for the next year that has Easter on the same date. You then look to see whether the two following years match too. They won't! So you look for the next matching year and keep going until you repeat indefinitely. Your program will take a long time!! "Calendrical Calculations" says: The dates of Easter repeat only after 5,700,000 years, the least common multiple of the 19-year Metonic cycle, the 400 years it takes for the Gregorian calendar to return to the same pattern of days of the week, the 4000 years it takes for the Gregorian leap-year corrections to add up to 30 days, and the 9375 years it takes for the correction to the Metonic cycle to amount to 30 days. If you get to understand the ecclesiastical moon and the ecclesiastical vernal equinox you will wonder whether the algorithm works at all. In fact it does a remarkably good job at predicting "the first Sunday after the first full moon after the vernal equinox" which is often given as the formal definition of Easter. What I should like to know is what is meant by Sunday! Sunday begins at different times in different places. Could it mean Sunday as it is timed at the longitude of Rome? Enough from me! Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Easter
H. If you ignore the pagan celebration of Oestre, then the first Easter began around 30 ad. Thus, there were no Easters before then. And, some factions of the Christian Church also have other definitions of Easter, or so I am told. I have always used the first Sunday after the first full moon after th Spring equinox. So, that adds some variables. :) Simon --- Frank King <[EMAIL PROTECTED]> wrote: > Dear Mac, > > Many thanks for your message... > > > If you can find the time, this mailing list member > ... > > would much appreciate details about how you > derived the > > list of dates. > > I am glad you asked this question and equally glad > that Patrick Powers has supplied the algorithm! > > I had it in my head that this algorithm was first > published in Butcher's Ecclesiastical Handbook in > 1876 and I give this as the (incorrect) citation in > one of my sets of student exercises. > > When I Googled "Butcher's Ecclesiastical Handbook" > all I got was a couple of references to plagiarised > versions of my exercises. Tee hee! I wouldn't have > discovered my error had you not prompted me to look > for something else! > > I first saw the algorithm in Meeus and now see that > he > gives the correct citation "Butcher's Ecclesiastical > Calendar, 1876". > > There is a reasonably complete account in: > > http://en.wikipedia.org/wiki/Computus > > One of my favourite books is "Calendrical > Calculations" > by Edward M. Reingold and Nachum Dershowitz. It is > full of good jokes! > > This book almost attributes the algorithm to Clavius > and Lilius (key figures in the Gregorian reform of > the calendar). > > Once you have implemented the algorithm you can then > have fun determining the length of the cycle. A > naive approach is to start at an arbitrary year and > look for the next year that has Easter on the same > date. You then look to see whether the two > following > years match too. They won't! So you look for the > next matching year and keep going until you repeat > indefinitely. Your program will take a long time!! > > "Calendrical Calculations" says: > > The dates of Easter repeat only after 5,700,000 > years, the least common multiple of the 19-year > Metonic cycle, the 400 years it takes for the > Gregorian calendar to return to the same pattern > of days of the week, the 4000 years it takes for > the Gregorian leap-year corrections to add up to > 30 days, and the 9375 years it takes for the > correction to the Metonic cycle to amount to > 30 days. > > If you get to understand the ecclesiastical moon > and the ecclesiastical vernal equinox you will > wonder whether the algorithm works at all. In > fact it does a remarkably good job at predicting > "the first Sunday after the first full moon after > the vernal equinox" which is often given as the > formal definition of Easter. > > What I should like to know is what is meant by > Sunday! Sunday begins at different times in > different places. Could it mean Sunday as it > is timed at the longitude of Rome? > > Enough from me! > > Frank > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Easter
Frank, "The Ecclesiastical Calendar" is a wonderful book and absolutely essential for anyone with an unhealthy interest in the labyrinthine workings of the church calendar. It was written by the Bishop of Meath during his spare time and describes in complete detail the development and theoretical foundations of the ecclesiastical calendar. Unfortunately, it is difficult to find and I have not seen a copy offered for sale but I did manage to borrow a copy from the British Library which I returned with great reluctance. Google Books have scanned a copy of the book and its description can be found at: http://books.google.com/books?id=qbA-rzFsIoMC but it cannot be downloaded in UK - apparently for copyright reasons although this seems highly conservative as the author died before publication in 1877. However, anyone accessing Google Books from the US may download a high-quality PDF copy of the book and I strongly recommend them to do so. Geoff -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Frank King Sent: 16 March 2008 21:43 To: Mac Oglesby Cc: sundial@uni-koeln.de Subject: Re: Easter Dear Mac, Many thanks for your message... > If you can find the time, this mailing list member ... > would much appreciate details about how you derived the list of dates. I am glad you asked this question and equally glad that Patrick Powers has supplied the algorithm! I had it in my head that this algorithm was first published in Butcher's Ecclesiastical Handbook in 1876 and I give this as the (incorrect) citation in one of my sets of student exercises. When I Googled "Butcher's Ecclesiastical Handbook" all I got was a couple of references to plagiarised versions of my exercises. Tee hee! I wouldn't have discovered my error had you not prompted me to look for something else! I first saw the algorithm in Meeus and now see that he gives the correct citation "Butcher's Ecclesiastical Calendar, 1876". There is a reasonably complete account in: http://en.wikipedia.org/wiki/Computus One of my favourite books is "Calendrical Calculations" by Edward M. Reingold and Nachum Dershowitz. It is full of good jokes! This book almost attributes the algorithm to Clavius and Lilius (key figures in the Gregorian reform of the calendar). Once you have implemented the algorithm you can then have fun determining the length of the cycle. A naive approach is to start at an arbitrary year and look for the next year that has Easter on the same date. You then look to see whether the two following years match too. They won't! So you look for the next matching year and keep going until you repeat indefinitely. Your program will take a long time!! "Calendrical Calculations" says: The dates of Easter repeat only after 5,700,000 years, the least common multiple of the 19-year Metonic cycle, the 400 years it takes for the Gregorian calendar to return to the same pattern of days of the week, the 4000 years it takes for the Gregorian leap-year corrections to add up to 30 days, and the 9375 years it takes for the correction to the Metonic cycle to amount to 30 days. If you get to understand the ecclesiastical moon and the ecclesiastical vernal equinox you will wonder whether the algorithm works at all. In fact it does a remarkably good job at predicting "the first Sunday after the first full moon after the vernal equinox" which is often given as the formal definition of Easter. What I should like to know is what is meant by Sunday! Sunday begins at different times in different places. Could it mean Sunday as it is timed at the longitude of Rome? Enough from me! Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Easter
Dear Simon, Geoff, Andrew, Mac, et al, I am most interested in all your observations. I am especially interested to hear that The Ecclesiastical Calendar is now on a PDF. > There may be a real and unexpected lesson > in statistics... The distribution certainly has quirks. Given that there are 35 possible dates and that the traditional life expectancy is three-score years and ten, the naive expectation is to see each date twice in a life time. This hardly concurs with reality! Nobody has yet explained what is meant by "Sunday"... When Pope Gregory XIII's Commission sorted out the Calendar they had to attend to the algorithm for the date of Easter. The new leap-year rule necessitated significant adjustments to the tables then in use. It seems most unlikely that the understanding of "Sunday" they had in mind ran from midnight UTC to midnight UTC!! One might suppose the longitude of Rome was used, or perhaps Jerusalem, or somewhere else? Even when you settle on the longitude, you still have to decide whether your two consecutive instants of inferior solar transit relate to the true sun or to the mean sun. Anyone know? Happy Easter Frank King, Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: easter
We had a 27-line Basic program for Easter, based on Butcher's method, in Sky & Telescope for March 1986, pages 294-295. It is available for free download from: http://www.skyandtelescope.com/resources/software/3304911.html?page=3&c=y (Scroll down that page to "EASTER.BAS") The original trio of short articles in our March 1986 issue also gives an even shorter program, written by me in Forth! And Gauss's method is listed as well. One of those articles discusses the procedure described in the Episcopal Church's Book of Common Prayer, 1928 edition, where Easter is calculated by means of the Golden Number. The time zone (Rome or anywhere else) doesn't enter into the calculation at all. The ecclesiastical rules for Easter do not rely on the astronomical phase of the Moon to determine the paschal full Moon on which Easter is based. Instead, the ecclesiastical rules unambiguously lead to a particular Sunday in any given year, and Easter is to be observed on that Sunday, local time. -- Roger From: [EMAIL PROTECTED] [EMAIL PROTECTED] On Behalf Of JC White - Casa del Potro [EMAIL PROTECTED] Sent: Wednesday, March 19, 2008 12:50 AM To: sundial@uni-koeln.de Subject: easter For an intriguing algorithm for calculating the date of easter, as proposed by the great German mathematician Gauss, see Fortran Programming by Robert V Jameson, McGraw-Hill, 1966, LCC number 65-27979 32271, page 150. This is the algorithm I used in my Basic language program... I will include the page with the copy of the Basic program to those who requested that program from me off list... John --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Easter Day
Interesting discussion on the determination of the date of Easter. What authority determines the date, or more precisely, what authority has formulated the rules for the determination of that date? Are these rules published? Is there a group or association which disputes these rules, and celebrates Easter on a different date? Thanks. George McDowell
Easter Sunday
-- From: Mario Arnaldi[SMTP:[EMAIL PROTECTED] Sent: quarta-feira, 8 de abril de 1998 23:33 To: sundial@rrz.uni-koeln.de Subject: :-) Caríssimo Mario, Thank you According with one extra-rule of the Gregorian Calendar in order the Easter do not fall before March 22 nor after April 25: The Easter is on the first Sunday after the Full Eclesiastical Moon, (the Full Moon on or after Eclesiastical Spring Equinox fixed on March 21) If that Sunday is after April 25 then the Easter is on the Sunday before. If the Full Eclesiastical Moon is on March 21 and that day is Sunday, then the Easter is on April 25. Not always the Spring Astronomical Equinox is on the same day that the Spring Eclesiastical Equinox. jorge N38 47 W9 19 Happy Easter to all. ...If you are too gnomonist for Easter, than, Happy first sundey after the new moon of Springtime to all. Hope everyone fill fine. Mario Arnaldi
Easter Sunday
Dear Meredith and All, On 1943 the Full Eclesiastical Moon was on March 21 at 22h09m, That day was Sunday so the Easter Sunday was on April 25. The Greenwich place you talked about, famous by the Nautical Tables made there later on, was hardly known at 1582 when these rules were established and when more than half of the world were already discovered even without those tables. We have a lot of software nowadays but I also use the old Gauss formulæ (from the german Karl-Friedrich Gauss 1777 - 1855). It is confortable to question the authority of those rules NOW. On XVI century one could be burnt like Giordano Bruno and many others... My respects jorge N38 47 W9 19
Easter Calculation
The LOng calculations for easter may be shortened to this algorithm that collected from Tommorows World in the Late 70's. It works from 1900 to 2099 only in contrast to the longer versions which are for any year(if the Calendar is not changed again ) E = year-1900 A = Remainder of E / 19 S = ( 7*A+1 ) / 19 ignore the remainder T = Remainder of ( 11*A + 4 - S) / 29 e = E / 4 ignore the remainder R = Remainder of ( E + e + 31 -T) / 7 Easter Day =25 -T - R The result is in days before or after 31 March ie 0 = 31 March +ve in April -ve in March For 2000 E=100 A=5 S=1 T=0 e=25 R=2 Easter Day =23 ie 23 April For 1989 E=89 A=13 S=4 T=27 e=22 R=3 Easter Day = -5 ie 25 March Hope this short method is of help Colin Davis
Easter Calculator
Dear Friends, Somebody recently posted a link to a text page about Easter and other ecclesiastical dates. On another page at that site there is what appears to be a very detailed and inclusive calculator: http://www.smart.net/~mmontes/ec-cal.html Bob Terwilliger
Happy Easter
Slawek Grzechnik 32 57.4'N 117 08.8'W http://home.san.rr.com/slawek
Fw: Easter
-Ursprüngliche Nachricht- Von: Werner Rauscher <[EMAIL PROTECTED]> An: Frank Evans <[EMAIL PROTECTED]> Datum: Donnerstag, 17. Juni 1999 00:32 Betreff: Re: Easter > >-Ursprüngliche Nachricht- >Von: Frank Evans <[EMAIL PROTECTED]> >An: Werner Rauscher <[EMAIL PROTECTED]> >Datum: Dienstag, 15. Juni 1999 19:38 >Betreff: Re: Easter > > >> >>>Frank, >>> >>>You've forgotten the new moon; there are spring tides too. >>> >>>Werner> >>> >>Greetings Werner. Yes, I wish it was so simple. I am a marine >>biologist by trade (retired) and know about tides. But two weeks before >>Easter and two weeks after Easter when new moon occurs my students are >>attending ordinary classes. The field course has to be in the holiday. >> >>Frank >>-- >>Frank Evans >> > >Hallo Frank, >please excuse my English, I know it's a little bit "rough". >Now to your easter-problem: >May be, the following website will help you (and give further informations): >http://tycho.usno.navy.mil/ >Greetings >Werner >
Easter egg
Hello Friends, For those of you who haven't already discovered Mike Shaw's nifty little surprise, point your browser at: http://homepage.ntlworld.com/jmikeshaw/index.html and click on "Picture Gallery." Then, watch as Mike's cute clock/calendar chases your cursor. Nice going, Mike! Mac Oglesby -
Date of Easter
List Members: Somewhere I have a computer program that calculates the date of Easter for any year after 1528... it is written in GW-BASIC, but I can convert it to Visual Basic for easy use under Windows... if any members of the list would like a copy I can send it attached to an email, if you request the program off-list. John [EMAIL PROTECTED] --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Easter Algorithm
I've set-up this algorithm on an Excel spreadsheet for a project to come. The results the spreadsheet generates come close in most cases to the actual date (either dead on or the day before - a rounding issue perhaps), but in some cases the difference is many days off. Have any of you toyed with this or have explanation of what I could do to make it more accurate? The spreadsheet I set up can be emailed to anyone interested as it's too big for this list. Thanks. Thad 45.3N 73.3W Patrick Powers <[EMAIL PROTECTED]> wrote: Mac Oglesby asked how one might begin to calculate the statistics for Easter as recently indicated by Frank. Now, I always thought that the algorithm which applies to any year since the introduction of the Gregorian Calendar, and which in Britain was in September 1752 is as given below. For those uninterested in its programming it can (I believe!) be found as a calculator for any year at: http://www.ely.anglican.org/cgi-bin/easter Whether it's correct I do not know but Frank indicated an Easter Cycle of 5,700,000 years and so to check, I entered the year 5702008. It yields Ash Wednesday 6 February 57002008 Palm Sunday 16 March 57002008 Good Friday 21 March 57002008 Easter Day 23 March 57002008 Ascension Day 1 May 57002008 Pentecost 11 May 57002008 Trinity Sunday 18 May 57002008 Advent Sunday 30 November 57002008 which is, as Frank points out, the same as for 2008, viz: Ash Wednesday 6 February 2008 Palm Sunday 16 March 2008 Good Friday 21 March 2008 Easter Day 23 March 2008 Ascension Day 1 May 2008 Pentecost 11 May 2008 Trinity Sunday 18 May 2008 Advent Sunday 30 November 2008 Patrick ___ Here's the algorithm that I think is used by the calculator: We refer to the year number as y, and use it to calculate the Golden number, g: g = y mod 19 + 1 Next we calculate the date of the Paschal full moon, that is, the full moon which Easter is the Sunday after. This is done in several stages. First we calculate two values called the solar correction, s, and the lunar correction, l. s = (y - 1600) div 100 - (y - 1600) div 400 l = (((y - 1400) div 100) × 8) div 25 Next we calculate an uncorrected date for the Paschal full moon, p'; then we apply a minor correction to get the exact date, p, as the number of days after 21st March. p' = (3 - 11g + s - l) mod 30 if (p' == 29) or (p' == 28 and g > 11) then p = p' - 1 else p = p' Now we need to determine the date of the following Sunday. First we calculate the 'Dominical number', d: d = (y + (y div 4) - (y div 100) + (y div 400)) mod 7 Note that this is the number from which the Dominical letter is determined, and we calculate d', which is the date on which the first Sunday of the year falls: d' = (8 - d) mod 7 We already have p, the date of the Paschal full moon in days after 21st March. Next we determine p'' the first date in the year which falls on the same day of the week as the Paschal full moon. First we determine the 'day number' of p with respect to 1st January. This is 31 + 28 + 21 + p = 80 + p. (Note that we can disregard possible occurences of 29th February, because the calculation of d has already taken this into account, and we shall see that these two values will cancel each other out.) p'' is then given by the formula: p'' = (80 + p) mod 7 = (3 + p) mod 7 The difference between d' (the first Sunday in the year) and p'' (the day of the week when the Paschal full moon falls) gives us the number of days that must be added to p to get the date of the following Sunday, which is Easter Day. There is one further subtlety. This number must lie in the range 1-7, rather than 0-6, since Easter is not allowed to fall on the same day as the Paschal full moon. We first determine x', the difference between d' and p'': x' = d' - p'' = (8 - d) mod 7 - (3 + p) mod 7 = (8 - d - (3 + p)) mod 7 = (5 - d - p)) mod 7 To force this to lie in the range 1-7, we calculate x x = (x' - 1) mod 7 + 1 = (4 - d - p)) mod 7 + 1 We can now calculate e, the number of days Easter falls after 21st March: e = p + x or e = p + 1 + (4 - d - p) mod 7 In other words Easter Day is: if e < 11 then (e + 21) March else (e - 10) April ___- --- https://lists.uni-koeln.de/mailman/listinfo/sundial - Never miss a thing. Make Yahoo your homepage.--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Easter Day
[EMAIL PROTECTED] writes: > ... In my school we just has our Arab > students out for very holy days, our Greek Orthodox students observe > Easter April 19, and my Unitarian friends take "spring break". I would have expected that the Orthodox churches define Easter in the same way as the Western churches, except that they use the Julian calendar. It seems that would make the Orthodox Easter on average 13 days later than the Western Eastern, but in any given year it would be either coincident or one month later. How did it end up one week later this year? Do they calculate the full moon differently as well? > ... So why > does Illinois call April 10, Good Friday, a state holiday? Is one > religion favored over another? But then Illinois has a state holiday > for Pulaski Day. Do other places have state holidays today - (Christian > Good Friday)? In Germany, Good Friday and Easter Monday are both state holidays (even though Easter Monday is not even a church holiday!). But Germany does not make any pretense of separating church and state. The state collects taxes for the church, the church appoints some university professors (not only for theology), and in Bavaria, classrooms are required to hang a crucifix. --Art Carlson--
Re: Easter Sunday
On Thu, 9 Apr 1998 14:48:08 +0100, you wrote: >If that Sunday is after April 25 then the Easter is on the Sunday before. >If the Full Eclesiastical Moon is on March 21 and that day is >Sunday, then the Easter is on April 25. This is not correct. In all Western countries (i.e., places which do not observe the Greek Orthodox calendar), then Easter Sunday is the first Sunday *after* the Paschal Moon, the Paschal Moon being defined as the full moon which occurs between March 21st and April 18th inclusive, using Greenwich midnight to resolve questions of dating. If the full moon falls upon a Sunday, then Easter is the following Sunday. So if the Paschal Moon were to fall on Sunday, March 21st, then Sunday, March 28th would be Easter Sunday. I believe this happened most recently in 1948. Incidentally, since the only way that Easter can fall on March 22nd is if the full moon falls on Saturday, March 21st, it's a pretty rare occurrence. Normally it happens once a century or so, but at present we're at a point in the moon's cycle in which it's impossible. The last March 22nd Easter was in 1818, and the next one will be in 2274. I think the last April 25th Easter was in 1943. Meredith Dixon [EMAIL PROTECTED]
Re: Easter Sunday
On Fri, 10 Apr 1998 17:05:40 +0100, Jorge Ramalho wrote: >We have a lot of software nowadays but I also use the old >Gauss formulæ (from the german Karl-Friedrich Gauss 1777 - 1855). Jorge, I am not using software either. I am using the tables of epacts (the Golden Numbers) from the Episcopalian *Book of Common Prayer*. I'm working from the 1928 edition, but the same rules have been in our prayer book since its inception in 1789, and I am fairly sure that they were taken directly from the Book of Common Prayer of the Church of England. Since they refer to "the new calendar" in a footnote, it is safe to assume that they were updated when England adopted the Gregorian Calendar, in the late 1700's, and, most likely, that they had existed in Julian form before then. The Book of Common Prayer is also my source for the explanation of how to find the date of Easter. Those tables are official within my church, and within its parent the Church of England. Since all of the West celebrates Christianity on the same date, and I'd expect some divergence if different formulae were in use by different churches, I'd always presumed the formulae were the same throughout Western Christendom. >On 1943 the Full Eclesiastical Moon was on March 21 at 22h09m, >That day was Sunday so the Easter Sunday was on April 25 . In 1943, the Golden Number for 1943 was 6. That means that the Paschal Moon fell on April 18th, the last day on which it can possibly fall. The moon's cycle as seen from earth takes 709 hours (29.5 days) so the full moon in March 1943 was on Saturday, March 20th, Greenwich time, one day too early to be the Paschal Moon. >The Greenwich place you talked about, famous by the Nautical Tables made >there later on, was hardly known at 1582 when these rules were established >and when more than half of the world were already discovered even without >those tables. True. You'll note that my verbatim quote of the official rules, below, doesn't mention Greenwich, but that's natural, since the tables were drawn up (as you point out) before the advent of universal time. Some rule for dating is needed, and that *does* seem to have been the rule followed -- I was curious about this point some years ago, and I checked then for ecclesiastical moon vs. astronomical moon and found that they matched exactly when the Greenwich date was used, though not always if I used my local date. This makes sense, of course, since these *are* the rules of the Church of England. Jorge, I suppose it's possible that the rule you keep citing, the bit about a March 21st Paschal Moon causing an April 25th Easter, is a local kludge intended to bring whatever your time zone is into sync with whatever was originally decided upon by the West. (I'm assuming that, and not assuming that yours is the original and mine is the kludge, because it seems so odd to have a rule affecting only the first day of a thirty-five-day time period.) Meredith Dixon [EMAIL PROTECTED] I append the relevant text from the Book of Common Prayer, pp. xxxv, xxxix: TO FIND THE DATE OF EASTER DAY The Numbers prefixed to the several Days, in the foregoing Calendar [a perpetual one], between the twenty-first Day of March and the eighteenth Day of April, both inclusive, denote the Days upon which those Full Moons do fall, which happen upon or next after the twenty-first Day of March, in those years of which they are respectively the Golden Numbers) and the Sunday Letter next following any such Full Moon points out Easter Day for that Year. All which holds until the Year of our Lord 2199 inclusive, after which Year, the places of the Golden Numbers will be to be changed, as is hereafter expressed. To find Easter Day, look in the first column of the Calendar, between the twentieth Day of March and the nineteenth Day of April [exclusive], for the Golden Number of the Year, against which stands the Day of the Paschal Full Moon. Then look in the third column for the Sunday Letter next after the Day of the Full Moon, and the Day of the Month standing against that Sunday Letter is Easter Day. If the Full Moon happen upon a Sunday, then (according to the first rule) the next Sunday after is Easter Day. To find the Golden Number, or Prime, add 1 to the Year of Our Lord, and then divide by 19; the Remainder, if any, is the Golden Number; but if nothing remain, then 19 is the Golden Number To find the Dominical or Sunday Letter for any given Year of Our Lord, add to the Year its fourth part, omitting fractions, and also the Number, which in Table I standeth at the top of the column wherein that given Year is found; divide the sum by 7, and if there be no Remainder, then A is the Sunday Letter, but if any number remain, then the Letter which standeth under that number at the top of the Table, is the Sunday Letter. Note: That in all Bissextile or Leap-years, the Letter found as
Re: Easter Sunday
After someone pointed out off-list that Easter will not in fact be on March 22nd in 2274, I double-checked my math and found that I'd apparently looked at the 1800's placement of the Golden Numbers, not the placement for the 2200's. (2274's Golden Number, like 1818's, is 14. Easter will *actually* next be on March 22nd in 2285. (Golden Number 6). And, to make the tables I posted a little more useful, first, the calendar referred to is a simple perpetual calendar in which January 1 is A. Feb, 29 has no letter, so March 1st is always D. The line in Table II for the 1900's, 2000's and 2100's is: 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 14 03 23 11 31 18 08 28 16 05 25 13 02 22 10 30 17 07 27 The first line above is the Golden Numbers, the second the date of the Paschal Moon. This year, we're Golden Number 4, ((1998+1)/19 = 105 with a remainder of 4 ), so the Paschal Moon is on the 11th. Meredith Dixon [EMAIL PROTECTED]
Re: Easter Sunday
Greetings All! > This is not correct. In all Western countries (i.e., places which do > not observe the Greek Orthodox calendar), then Easter Sunday is the > first Sunday *after* the Paschal Moon, the Paschal Moon being defined > as the full moon which occurs between March 21st and April 18th > inclusive, "using Greenwich midnight to resolve questions of dating." Well, that explains *that* little problem!! What problem? Here on Guam, full moon is *on* Easter Sunday this year. Of course, I do live where the world's day begins! Pam === | Pam Eastlick | Email: [EMAIL PROTECTED] | | Planetarium Coordinator | Voice: (671) 735-2783 | | CAS/DNS | Fax : (671) 734-1299 or -4582 | | UOG Station | Location : 13.25N, 144.47E | | Mangilao, Guam USA 96923 | Time : GMT+10EST+15 | | | |LOOK UP TONIGHT, THE UNIVERSE AWAITS YOU!| ===
Re: Easter Day
> [EMAIL PROTECTED] writes: > > > ... In my school we just has our Arab > > students out for very holy days, our Greek Orthodox students observe > > Easter April 19, and my Unitarian friends take "spring break". > > I would have expected that the Orthodox churches define Easter in the > same way as the Western churches, except that they use the Julian > calendar. It seems that would make the Orthodox Easter on average 13 > days later than the Western Eastern, but in any given year it would be > either coincident or one month later. How did it end up one week > later this year? Do they calculate the full moon differently as well? > > --Art Carlson-- Together with the Gregorian calendar also a new rule for calculating the date of Easter was introduced. Please note that in both Julian and Gregorian calendars the full moon is calculated not according to the real moon, but with respect to a fictitious moon. I guess the difference comes from the way the moon is defined. However, I am not an expert in this. I will try to find out with the help of the HASTRO-L discussion group how the date of Easter is calculated by the Orthodox churches. Wolfgang Dick
Re: Easter Day
Hi George and All, Sky and Telescope has the following site that has many BASIC programs that calculate dates of Easter, dates of full moons, sundials, etc. <http://www.skypub.com/software/software.shtml#list> Jean Meeus includes algorithms for finding Easter in several of his books on astronomy for the PC. I find the date of Easter, and its recognition as a state holiday, is an interesting test for any state or nation for their constitutionality of "separation of church and state". In my school we just has our Arab students out for very holy days, our Greek Orthodox students observe Easter April 19, and my Unitarian friends take "spring break". So why does Illinois call April 10, Good Friday, a state holiday? Is one religion favored over another? But then Illinois has a state holiday for Pulaski Day. Do other places have state holidays today - (Christian Good Friday)? George L. McDowell, Jr. wrote: > Interesting discussion on the determination of the date of Easter. > What > authority determines the date, or more precisely, what authority has > formulated the rules for the determination of that date? Are these > rules > published? Is there a group or association which disputes these rules, > > and celebrates Easter on a different date? Thanks. > > George McDowell
Easter Day and calendars
A good short history of calendars and the date of Easter can be found at: http://astro.nmsu.edu/~lhuber/leaphist.html Bruno [EMAIL PROTECTED]
Date of Easter again
Dear all, It is incredible how a simple joke of mine caused a so big discussion! Jorge Ramalho kindly reminded me my error using the terminology of Easter in my wishes to you all, and he was right. To make a short message I didn' care the perfection, but by the way it's still Easter this year, and I still wish you a happy Easter. Don't think too much, and don't eat too chocolate's Easter eggs, please leave some there for cildren (let me joke a little, I'd worked too much this week). Mario P.S. Sorry problems on the server didn't let me send this message in time. MARIO ARNALDI Viale Leonardo, 82 48020 Lido Adriano RAVENNA ITALY E-Mail - [EMAIL PROTECTED]
Re: Orthodox Easter (fwd)
Dear HASTRO-L members, Thanks to all who replied to my request concerning the date of Easter. I have also received an reply in German from Heiner Lichtenberg, who does not subscribe to HASTRO-L. He is a specialist in this matter. Unfortunately, I do not have the time to translate his reply, although this would be worth, but I will give a summary: The point seems to be that both methods of calculating Easter uses a fictitious moon, but that the Gregorian moon is closer to the real one. The Julian moon moves slower than the Gregorian one and is at present 4 days behind the latter. The first Gregorian full moon after the March equinox was on 11 April 1998, thus Easter was celebrated on 12 April. The Julian full moon was on 15 April (2 April in the Julian calendar), so Easter according to the Julian calendar was celebrated on 19 April (6 April in the Julian calendar). Heiner Lichtenberg refers to his publications in "Sterne und Weltraum" and comments also on the plans of the World Council of Churches to change the rules. I will add herafter the German text of the reply for those who are able to read it. Wolfgang Dick Forwarded message: > Date: Thu, 23 Apr 1998 14:17:43 +0200 > X400-Originator: [EMAIL PROTECTED] > To: [EMAIL PROTECTED] > Subject: orthodoxes Osterfest > > Lieber Herr Dick! > > Die orthodoxen Kirchen, jedenfalls wohl die groesseren, berechnen das > Osterfest nach dem Julianischen Kalender. Tut man dies fuer dieses Jahr, so > findet man den 6. April 1998 im Julianischen Kalender. Der zyklische Vollmond > im Julianischen Kalender ist der 2. April 1998. Rechnet man diese Daten in den > Gregorianischen Kalender um, so findet man als julianisch-zyklischen Vollmond > den 15. April 1998 und als (julianischen) Ostersonntag den 19. April 1998. > > Der gregorianisch-zyklische Vollmond faellt dagegen auf den 11. April 1998 > und der (gregorianische) Ostersonntag auf den 12. April 1998. > > Dass der julianisch-zyklische Mond dem gregorianisch-zyklischen Mond > hinterherhinkt, ist kein Wunder, denn jener hat die (synodische) Umlaufzeit > von > 27759 / 940 = 29,53085 ... Tagen, waehrend dieser die Umlaufzeit von > 2081882250 > / 70499183 = 29,5305869 ... Tagen hat. Der julianisch-zyklische Mond ist also > langsamer als der gregorianisch-zyklische Mond. Die jetzt bestehende Differenz > von 4 Tagen zwischen diesen beiden Monden geht allerdings nur zu einem Viertel > auf die geringere Umlaufgeschwindigkeit des julianischen Kalendermonds > zurueck. > Drei Viertel, namlich 3 Tage, beruhen auf einem Vorwaertssprung, den die > Kalenderordner (Lilius, Clavius usw.) den gregorianischen Kalendermond bei der > Reform 1582 ausfuehren liessen, naemlich beim Uebergang vom 4. Oktober 1582 > (jul.) auf den 15. Oktober 1582 (greg.). > > Die obigen Dinge sind nachlesbar in meiner SuW-Arbeit aus 1994 (Die Struktur > des Greg. Kal., anhand der Schwankungen des Osterdatums entschluesselt), Heft > 3, Seite 194, sowie in der neuesten Arbeit aus diesem Jahr (Die Struktur des > Greg. Kal., anhand einer Verallgemeinerung der Gauss'schen Osterformel > dargestellt), Heft 4, Seite 326. In der zuletzt genannten Arbeit findet man > auch bequeme Formeln zur Berechnung der Ostervollmonde, julianisch wie > gregorianisch. > > Die synodische Umlaufzeit des realen Mondes betraegt 29,530588 Tage; der > diesjaehrige reale Vollmond fiel auf den 11. April nach MEZ bzw. auf den 12. > April nach MESZ. Man sieht daraus, mit welch' erstaunlicher Praezision das > gregorianisch-zyklische Rechnen erfogt. Nichts desto trotz will es der > Weltkirchenrat im Jahre 2001 abgeschafft wissen! Es sei mir hier der Hinweis > auf einen entsprechenden "Aufschrei" um neuesten Heft (Nr. 5) von SuW > gestattet: "Foerderung der Kircheneinheit durch Kulturzerstoerung?". Jedoch > mit Schreien ist es nicht getan. Wir werden zeigen, welche Nuecken und Tuecken > sich beim Wechsel vom zyklischen zum Ephemeridenrechnen auftun. Das ist dem > Weltkirchenrat wohl noch nicht richtig bewusst. Am Ende steht man mit drei > Osterterminen da: dem julianischen, dem gregorianischen und dem > weltkirchenraetlichen Ostertermin. > > Herzliche Gruesse sendet Ihnen > > Heiner Lichtenberg
Re: Orthodox Easter (fwd)
Dear sundialers, Since the request concerning the date of Easter was also of interest for me, I forwarded it to HASTRO-L and to a German specialist. The reply of the latter I have distributed already in the previous message. Here follows another reply together with the text of my request. I will also forward some more replies. My apologies for the off-topic discussion, but it seems to me of general interest. Kind regards, Wolfgang Dick Forwarded message: > Date: Wed, 22 Apr 1998 10:41:13 -0500 > Reply-To: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > Sender: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > From: Voula Saridakis <[EMAIL PROTECTED]> > Subject: Re: Orthodox Easter > To: [EMAIL PROTECTED] > > Dear All: > > During the first centuries of Christianity there was no fixed date for the > celebration of Easter. In 325 AD the First Ecumenical Council among it's > other decisions established the guidelines for calculating the date of > Easter for all Christians. The Council agreed that Easter should be > celebrated on the first Sunday after the full moon for the spring equinox > provided that the Jewish Passover had already been celebrated with the last > provision being the most important. > However these calculations were based on the Julian calendar which was > scientifically incorrect. After the Roman Catholic Church adopted the > Gregorian calendar, it dropped the practice of celebrating Easter only after > the Jewish Passover had taken place. Since 1582 the Western Churches, Roman > Catholic and Protestant Churches, have observed Easter irrespective to the > date of Passover and hence, Eastern Orthodox Christians believe the Western > churches are historically incorrect in their observance of this holiday. > Hence the Eastern Orthodox Church is the only branch of Christianity that > continues to celebrate Easter on the date that, to them, is historically > correct according to the New Testament and the decrees of the First > Ecumenical Council. > > Sincerely, > > Voula Saridakis > > > >The following request and reply comes from the Sundial Mailing List: > > > >> [EMAIL PROTECTED] writes: > >> > >> > ... In my school we just has our Arab > >> > students out for very holy days, our Greek Orthodox students observe > >> > Easter April 19, and my Unitarian friends take "spring break". > >> > >> I would have expected that the Orthodox churches define Easter in the > >> same way as the Western churches, except that they use the Julian > >> calendar. It seems that would make the Orthodox Easter on average 13 > >> days later than the Western Eastern, but in any given year it would be > >> either coincident or one month later. How did it end up one week > >> later this year? Do they calculate the full moon differently as well? > >> > >> --Art Carlson-- > > > >I am also interested in this question because I have relatives and friends in > >Russia and the Ukraine, and we wondered about the different dates of Easter. > >What I learned from a large encyclopedia is that together with the Gregorian > >calendar also a new rule for calculating the date of Easter was introduced. > >However, in both Julian and Gregorian calendars the full moon is calculated > >not > >according to the real moon, but with respect to a fictitious moon. I guess > >the > >difference comes from the way the moon is defined. However, I am not an > >expert > >in this. So, does someone know how the date of Easter is calculated by the > >Orthodox churches? > > > >Wolfgang Dick, Germany > > *^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^* > > Voula Saridakis [EMAIL PROTECTED] > Department of History office: (540)231-8362 > 428 Major Williams fax: (540)231-8724 > OR > Science and Technology Studies > 124 Lane Hall > > Virginia Polytechnic Institute and State University > Blacksburg, VA 24061 > USA > > *^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*^*
Re: Orthodox Easter (fwd)
Forwarded message: > Date: Wed, 22 Apr 1998 08:12:05 -0700 > Reply-To: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > From: Leigh Palmer <[EMAIL PROTECTED]> > Subject: Re: Orthodox Easter > To: [EMAIL PROTECTED] > > For the determination of dates of movable feasts see "The Explanatory > Supplement to the Astronomical Ephemeris and the American Ephemeris > and Nautical Almanac". The Eastern rite uses an astronomical algorithm > while the Roman rite uses a numerological algorithm to determine these > dates. > > Leigh
Re: Orthodox Easter (fwd)
Forwarded message: > Date: Wed, 22 Apr 1998 17:01:14 -0500 > Reply-To: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > From: "David J. Ross" <[EMAIL PROTECTED]> > Subject: Re: Orthodox Easter > To: [EMAIL PROTECTED] > > Regarding this thread, readers may be interested to know that there have been > discussions for several years now between Eastern and Western churches > regarding > the adoption of a common date for Easter. As reported in the Christian > Century > (April 15h), if adopted the change would take affect in 2001 when the dates > coincides under both methods of computus. "At the Aleppo meeting (held under > the > aupices of the World Council of Churches last year), representatives of the > world's major Christian groups agreed on a proposal that would calculate the > date > of Easter based on the fourmula developed by the First Ecumenical Council of > Nicaea in 325 a.d. but using more modern astronomical techniques." So, the > matter is indeed of some currency. > > Rev. David Ross > Canton, Ohio
Re: Orthodox Easter (fwd)
Forwarded message: > Date: Wed, 22 Apr 1998 22:47:02 -0500 > Reply-To: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > From: "David J. Ross" <[EMAIL PROTECTED]> > Subject: Re: Orthodox Easter > To: [EMAIL PROTECTED] > > Friends, > > I happened to find a WCC press release on the aforementioned which actually > credits > the astronomers with the needed solution... > > > http://cssa.stanford.edu/~marcos/pr.wcc.19970324.html > > Dave Ross For those who do not have access to the WWW I will add the interesting press release: World Council of Churches Press Release For Immediate Use 24 March 1997 THE DATE OF EASTER: SCIENCE OFFERS SOLUTION TO ANCIENT RELIGIOUS PROBLEM Senior church representatives have come up with an ingenious proposal to set a common date for Easter. At present, churches in the East and West celebrate Easter, the Resurrection of Jesus Christ from the dead, on two different dates in most years. It has long been recognised that to celebrate this fundamental aspect of the Christian Faith on different dates gives a divided witness and compromises the churches' credibility and effectiveness in bringing the Gospel (good news) to the world. At a recent consultation in Aleppo, Syria (5-10 March), organised by the World Council of Churches and the Middle East Council of Churches, representatives of several churches and Christian world communions became convinced a solution to the problem is possible, based on modern astronomical science. Churches in the East and West calculate the date of Easter by the same principle. This is the one given by the Council of Nicea in 325 which determined that Easter should be celebrated on the Sunday following the first full moon after the March equinox. Differences in dating occur because churches follow different calculations of the equinox and the full moon. The recent Aleppo gathering has proposed that, from the year 2001 the date of Easter should be calculated using precise modern astronomical determinations. In this way, the Nicea principle will be preserved and neither churches in the East or West will have to change their policy. Astronomical observations, of course, depend upon the position on earth which is taken as a point of reference. Therefore, it is proposed that the basis for reckoning be the meridian of Jerusalem, the place of Christ's death and resurrection. The consultation proposal will be sent to churches throughout the world together with a chart showing possible dates for Easter in the first 25 years of the 21st century if their suggestion is accepted. The chart also shows the dates if calculated by the old methods. The consultation recognised that differences in dating Easter are not due to fundamental theological differences, but also acknowledged that past attempts to address this thorny question have led to schism. Churches in the East will be most affected by the new dating system. However, in the Middle East and Eastern Europe, where Christian churches have lived with the challenge of other religions or materialistic ideologies, loyalty to the *old calendar* has been a symbol of the churches' desire to maintain their integrity and freedom from the hostile forces of this world. The consultation therefore concluded that there will be need for great pastoral sensitivity among church members as the proposal is pursued. It is suggested that the new method of calculation begin in 2001 when the date of Easter, using the old methods and the new, will be the same, viz 15 April, and that a common date be kept from then on. However, before that can happen, churches must consider the proposal and give their reactions. The consultation called on the WCC to organise a meeting between now and 2001 to receive reports and discuss possible implementation. Represented at the consultation were: Anglican Communion, Armenian Orthodox Church, Ecumenical Patriarchate, Evangelical Churches in the Middle East, Greek Orthodox Patriarchate of Antioch, Lutheran World Federation, Middle East Council of Churches, Old-Catholic Churches of the Union of Utrecht, Patriarchate of Moscow, Pontifical Council for Promoting Christian Unity, Seventh-day Adventists. The Syrian Orthodox Church hosted the meeting. Consultants came from the Orthodox Church in America and the Pentecostal Assemblies of Canada. Fr Dr Thomas FitzGerald (director) and Rev Dr Dagmar Heller (executive secretary) from WCC Unit I: Unity and Renewal staffed the gathering and are available for interview. A 9-page briefing paper prepared by the consultation is available upon request. ** The World Council of Churches is a fellowship of churches, now 330, in more than 100 countries in all continents from virtually all Christian traditions. The Roman Catholic Church is not a member church but works cooperatively with the WCC. The high
Re: Orthodox Easter (fwd)
Forwarded message: > Date: Wed, 22 Apr 1998 23:17:45 -0500 > Reply-To: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > From: "David J. Ross" <[EMAIL PROTECTED]> > Subject: Re: Orthodox Easter > To: [EMAIL PROTECTED] > > Ok, one last comment, this address for a concise FAQ document, with links, on > the > matter of the date's calculation and some history. Hope I've not been a > pest > > DR > > www.landfield.com/faqs/astronomy/faq/part3/section-11.html Again the test for those who do not have access: When is Easter? John Harper <[EMAIL PROTECTED]> The "popular" rule (for Roman Catholics and most Protestant denominations) is that Easter is on the first Sunday after the first full moon after the March equinox. The actual rule is similar, except that the astronomical equinox is not used; the date is fixed at March 21. And the astronomical full moon is not used; an "ecclesiastical" new moon is determined by adopted tables based on the Metonic cycle, and "full" is taken as the 14th day of that lunation. There are auxiliary rules that make March 22 the earliest possible date for Easter and April 25 the latest. The intent of these rules is that the date will be incontrovertibly fixed and determinable indefinitely in advance. In addition it is independent of longitude or time zones. The popular rule works surprisingly well. When the two rules give different dates, that occurs in only part of the world because two dates separated by the international date line are simultaneously in progress. The Eastern Churches (most Orthodox and some others, e.g., Uniate Churches in Palestine) use the same system, but based on the old (Julian) calendar. In that calendar, Easter Day is also between March 22 and April 25, but in the western (Gregorian) calendar those days are at present April 3 and May 8. Whenever the Gregorian calendar skips a leap year, those dates advance one day. Some Eastern Churches find both movable feasts like Easter and fixed ones like Christmas with the Julian calendar; some use the Julian for movable and the Gregorian for fixed feasts; and the Finnish Orthodox use the Gregorian for all purposes. To explain the Eastern system one must begin with the Jews in Alexandria at the time of the Christian Council of Nicaea in 325, who appear to have been celebrating Passover on the first "full moon" after March 21, as specified by the 19-year Metonic cycle and the Julian calendar (with its leap year every 4 years, end of century or not). The Bishop of Alexandria was made responsible for the Christian calendar; he specified that Easter be the Sunday after that Passover. Eastern Christians still say that Easter must follow Passover, but that Passover is the one that is meant, not the Passover defined by the present Jewish calendar. Subsequently the Jews reformed their calendar (in 358 or in the early 6th century according to different sources; possibly at different times in different places), in order to improve the fit between astronomy and their arithmetic, but the Christians did not follow suit. In 1996, for example, Passover was on April 4 but the Orthodox Easter was on Sunday April 14, not April 7 (which as it happens was the Western Easter.) The Eastern Easter is 0, 1, 4, or 5 weeks after the Western Easter. The Western Easter can precede the (modern) Jewish Passover, as in 1967, 1970, 1978, 1986, 1989 and 1997, and can even coincide with it, as in 1981. Much of this information was taken from the Explanatory Supplement to the Astronomical Ephemeris, page 420, 1974 reprint of the 1961 edition. There is more in the Explanatory Supplement, specifically a series of tables that can be used to determine the Easter date for both the Julian (Eastern and pre-1582 Western) and Gregorian calendars. However, the Explanatory Supplement is misleading on the subject of the Eastern Easters, though its tables are correct. Jean Meeus has published a program to compute Easter in "Astronomical Algorithms," also see below. Simon Kershaw has written one in C, available at http://www.ely.anglican.org/cgi-bin/easter>. The most easily available published source for what the Jews and Christians were doing in ancient Alexandria appears to be Otto Neugebauer's "Ethiopic Easter Computus" in his _Astronomy and History Selected Essays_, Springer, New York, 1983, pp. 523--538. John Harper acknowledges the help of Archimandrite Kyril Jenner, Simon Kershaw, and Dr. Brian Stewart concerning Eastern Easters.
Re: AW: Orthodox Easter (fwd)
Forwarded message: > Date: Mon, 27 Apr 1998 18:03:07 -0500 > Reply-To: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > Sender: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > From: "David J. Ross" <[EMAIL PROTECTED]> > Subject: Re: AW: Orthodox Easter (fwd) > To: [EMAIL PROTECTED] > > Professor Lourie in St. Petersberg responded with the following remarks to the > cross post that I forwarded regarding the Easter computus, as it is known; it > seems his remarks and references may still be of interest. > > Rev. Dave Ross > > > From: >Basil Lourie <[EMAIL PROTECTED]> > Reply-To: >Christianity in Late Antiquity Discussion Group > <[EMAIL PROTECTED]> > To: >Multiple recipients of list ELENCHUS <[EMAIL PROTECTED]> > > > > > There are, in our days, three forms of the Christian Easter computus. > > Gregorian calendar is adopted not only by the Western Christians, but also > by a diocese of the Patriarchate of Constantinople -- the Autonomous Church > of Finland (since 1924 or perhaps 1926 -- sorry for this inexactitude). > > Julian calendar (completely or only as regard to the Easter computus) is > retained by all other Oriental communities (not only Chalcedonian, but also > others) with unique exception of the Church of Ethiopia. > > The Easter computus of the Ethiopian Church is even more archaic: it > corresponds to the Alexandrian computus before the middle of IIIth century. > On this see: O. Neugebauer, _Ethiopic Astronomy and Computus_ Wien 1979 > (Oesterreichische Akademie der Wiss., Philos.-hist. Kl., Sitzungsberichte, > Bd. 347; Voroeffenlichungen der Komission fuer Geschichte der Mathematik, > Naturwissenschaften und Medizin, H. 22). > > Also very useful are (I limite to the modern authors where the most part of > the > references to the earlier literature are available): > > O. Neugebauer. _Abu Shaker's "Chronography". A Treatise of the 13th Century > on Chronological, Calendrical and Astronomical Matters, written by a Christian > Arab, presented in Ethiopian_ Wien 1988 (Oesterreichische Akademie der Wiss., > Philos.-hist. Kl., Sitzungsberichte, Bd. 498). > > M. Richard. Le comput pascal par octa/et/eris, _Le Mus/eon_ 87 (1974); repr. > in > Idem, _Opera minora_ I, Leuven 1976, # 21, p. 307-339. > > There are also some works on the particular systems, such as the history of > the > Eastern computus in Georgian or in Armenian Churches or on the calendars of > the Jewish world of the 2nd Temple period (based, first of all, on the > Qumranic > data). > > Basil Lourie > > St.Petersburg Society for > Byzantine and Slavic Studies > > [EMAIL PROTECTED] > > RUSSIA 194356 > St.Petersburg > pr.Engelsa 135-132 > B.Lourie > Fax 7(812) 559 > > > > > Eugene F. Milone wrote: > > > Yes, I agree that the problem of Easter is solvable in the Gregorian context > > alone; that's why I thought the Julian Calendar issue was a 'red herring'. > > Sources indicate that only the Slavonic churches are on the 'Old (i.e., > > Julian) > > Calendar' at present. I have no information about when the other Orthodox > > churches moved to the 'New Calendar'. But the interesting thing is that > > all the Orthodox celebrate Easter on the same date -- unlike Christmas, > > which is rooted in the 13d difference between the Julian & Gregorian > > calendars. > > Cordially, > > - gene milone
Easter ( a bit off topic)
I believe that for calculation by simple souls Easter is just the first Sunday after the first full moon after the equinox of 21 March. But I would like to find Easter several years ahead and do not know where to find lunar phases except for the current year. Or is there a handy table somewhere. There is one in the Oxford Companion to English Literature, extending over hundreds of years but it ends at the year 2000. Can anyone help, please? -- Frank Evans
Re Dates for Easter etc
Frank: Hope this helps: To the Year 2029: YearAsh Wed Easter 199712 February 30 March 199825 February 12 April 199917 February 4 April 2000 8 March23 April 200l28 February 15 April 2002 13 February31 March 2003 5 March20 April 200425 February 11 April 20059 February 27 March 2006 1 March16 April 200721 February 8 April 20086 February 23 March 200925 February 12 April 201017 February 4 April 20119 March 24 April 201222 February 8 April 201313 February 31 March 20145 March 20 April 201518 Febroary 5 April 2016 10 February27 March 20171 March 16 April 2018 14 February1 April 2019 6 March21 April 202026 February 12 April 202117 February 4 April 2022 2 March17 April 2023 22 February9 April 202414 February 31 March 20255 March 20 April 202618 February 5 April 202710 February 28 March 20181 March 16 April 202914 February 1 April Regards Patrick
Equinox, Full Moon and Easter
I always thought Easter Sunday was on the first Sunday after the first full moon after the spring equinox. This year at my location, time zone PDST, the equinox is at 2:59 pm Wed 20 March 2019. The full moon is about 4 hours later at 6:43 pm. Why is this Sunday not Easter and Friday not Good Friday. What about the Passover. It is also a month later. I know setting the date of Easter was the problem that inspired astronomy but this year the scientific data and the religious credo do not seem to agree. Where have I been mislead? (other than finding silly girls posing as sundials) Roger Bailey Walking Shadow Designs N 48.669°, W 123.403° --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Easter ( a bit off topic)
Any rule for calculating the celebration of Easter depends on whether you are interested in the Western or Orthodox holiday. Furthermore, any calculations for the future will become wrong if the rules are changed. See, for example, http://www.smart.net/~mmontes/pr.wcc.19970324.html --Art Carlson
Re: Easter ( a bit off topic)
> I believe that for calculation by simple souls Easter is just the first
> Sunday after the first full moon after the equinox of 21 March. But I
> would like to find Easter several years ahead and do not know where to
> find lunar phases except for the current year. Or is there a handy
> table somewhere. There is one in the Oxford Companion to English
> Literature, extending over hundreds of years but it ends at the year
> 2000. Can anyone help, please?
> --
> Frank Evans
Here is a C implementation of Meeus's Easter algorithm
#include
#include
/* Credit to Jean Meeus. */
main(int argc, char *argv[])
{
int year, a, b, c, d, e, f, g, h, i, k, l, m, n, p;
if ( argc != 2 )
{
fprintf(stderr, "Usage: %s year\n", argv[0]);
exit(1);
}
year = atoi(argv[1]);
a = year % 19;
b = year / 100;
c = year % 100;
d = b / 4;
e = b % 4;
f = (b + 8) / 25;
g = (b - f + 1) / 3;
h = (19 * a + b - d - g + 15) % 30;
i = c / 4;
k = c % 4;
l = (32 + 2 * e + 2 * i -h -k) % 7;
m = (a + 11 * h + 22 * l) / 451;
n = (h + l - 7 * m + 114) / 31;
p = (h + l - 7 * m + 114) % 31;
printf("Easter %d is %s %d.\n", year, n == 3 ? "March" : "April", p + 1);
}
Re: Easter ( a bit off topic)
>I believe that for calculation by simple souls Easter is just the first >Sunday after the first full moon after the equinox of 21 March. But I >would like to find Easter several years ahead and do not know where to >find lunar phases except for the current year. Or is there a handy >table somewhere. Jean Meeus has published a method for finding the date of Easter Sunday in "Astronomical Algorithms". It is valid for all years in the Gregorian calendar. Divide.by...QuotientRemainder The year ...19...a The year100...bc b..4d... .e b+8...25...f b-f+1.3.g 19a+b-d-g+1530.h c...4..ik 32+2e+2i-h-k.7l a+11h+22*l451.m h+l-7m+114.31..np Then n = number of the month p+1 = day of the month on which Easter Sunday falls. Les Cowley Mail~ [EMAIL PROTECTED] Halos ~ http://dspace.dial.pipex.com/lc/halo/halosim.htm
Re: Easter ( a bit off topic)
Quoted from "Practical Astronomy With Your Calculator" 3rd Edition, by
Peter Duffett Smith
1988, Cambridge University Press.
The date of Easter
Easter day, the date to which such moveable feasts as Whitsun and Trinity
Sunday are fixed, is
usually the first Sunday after the fourteenth day after the first new Moon
after March 21st. (For a
more precise definition see The Explanatory Supplement to the Astronomical
Ephemeris and
American Ephemeris and Nautical Almanac.) You can find the date of Easter
Sunday by the
method and tables given, for example, in the Book of Common Prayer, 1662,
or by one of
several methods devised by various mathematicians over the centuries. Here
I shall describe a
method devised in 1876 which first appeared in Butcher's Ecclesiastical
Calendar, and which is
valid for all years in the Gregorian calendar, that is from 1583 and
onwards. It makes repeated
use of the result of dividing one number by another number, the integer
part being treated
separately from the remainder. A calculator displays the result of such a
division as a string of
numbers before and after a decimal point. The numbers appearing before the
decimal point
constitute the integer part; the numbers after the decimal point constitute
the fractional part. The
remainder may be found from the latter by multiplying it by the divisor
(i.e. the number you have
just divided by) and rounding the result to the nearest integer value. For
example, 2000/19 =
105.263 157 9. The integer part is 105 and the fractional part is 0.263 157
9. Multiplying this by
19 gives 5.00 100 so that the remainder is 5. I shall illustrate the
method by calculating the
date of Easter Sunday in the year 2000.
Method
Integer part
Remainder
1. Divide the year by 19
a
example: 2000/19=105.2631579
a=5
2. Divide the year by 100 b
c
example: 2000/100=20.00
b=20 c=0
3. Divide b by 4 d
e
d=5 e=0
4. Divide (b+8) by 25 f
f=1
5. Divide (b-f+1) by 3 g
g=6
6. Divide (19a+b-d-g+15) by 30 h
h=29
7. Divide c by 4 i
k
i=0 k=0
8. Divide (32+2e+2i-h-k) by 7L
l=3
9. Divide (a+11h+22L) by 451 m
m=0
10. Divide (h+L-7m+114) by 31n p
n=4 p=22
11. Day of the month on which Easter Sunday
falls is p+1
p+1=23
Month number is n (=3 for March and =4
for April).
Easter Sunday 2000 is 23rd April
At 08:09 PM 6/10/99 +0100, Frank Evans wrote:
>I believe that for calculation by simple souls Easter is just the first
>Sunday after the first full moon after the equinox of 21 March. But I
>would like to find Easter several years ahead and do not know where to
>find lunar phases except for the current year. Or is there a handy
>table somewhere. There is one in the Oxford Companion to English
>Literature, extending over hundreds of years but it ends at the year
>2000. Can anyone help, please?
>--
>Frank Evans
Re: Easter ( a bit off topic)
Re: Easter ( a bit off topic)
Maybe the following basic code could be of help 10 REMEASTER 12 REM 14 INPUT "YEAR ";Y 16 IF Y<1583 THEN 14 18 Y1=Y/19 20 A=INT((Y1-INT(Y1))*19+.001) 22 B1=Y/100: B=INT(B1) 24 C=INT((B1-INT(B1))*100+.001) 26 D1=B/4: D=INT(D1) 28 E=INT((D1-INT(D1))*4+.001) 30 F=INT(((B+8)/25)+.001) 32 G=INT((B-F+1)/3) 34 H1=(19*A+B-D-G+15)/30 36 H=INT((H1-INT(H1))*30+.001) 38 C1=C/4: I=INT(C1) 40 K=INT((C1-I)*4+.001) 42 L1=(32+2*E+2*I-H-K)/7 44 L=INT((L1-INT(L1))*7+.001) 46 M=INT((A+11*H+22*L)/451) 48 N1=(H+L-7*M+114)/31: N=INT(N1) 50 P=INT((N1-N)*31+.001) 52 N$="APRIL" 54 IF N=3 THEN N$="MARCH" 56 PRINT "EASTER IS ON ";N$;P+1 58 INPUT "ANOTHER (Y OR N) ";Q$ 60 IF Q$="Y" THEN 14 62 END 70 REM 80 REM APPEARED IN ASTRONOMICAL 90 REM COMPUTING, SKY & TELE- 95 REM SCOPE, MARCH, 1986 99 REM Hope this helps Dave Carlson
Easter Greetings card from the AARS
The Asociacion de Amigos de los Relojes de Sol wishes you all happy Easter holidays and invites you to take a glance at our new Greetings card at http://www.relojesdesol.org/EasterGreetings.html The picture shows the exact point of the Geographic North Pole some days ago. As you all know, in the North Pole there is a candy-cane stake... Well, there it is! We have adapted it to serve as an horizontal plus equatorial plus analemmatic plus azimuthal dial, all in one. The golden line is the Prime Meridian (when it reaches Greenwich it is made of brass so that it isn't stolen) and the dots and numbers show Solar Time on such meridian. At the moment there is no EoT correction plaque, so donations are welcome ;-) Please notice that we only need half a plaque because in autumn and winter the dial does not work! Best wishes, Anselmo Perez Serrada www.relojesdesol.org -
Re: Equinox, Full Moon and Easter
Roger, the Easter calculation uses March 21 as the equinox irrespective of the astronomy. Steve On Tue, Mar 19, 2019 at 21:00, Roger wrote: > I always thought Easter Sunday was on the first Sunday after the first > full moon after the spring equinox. This year at my location, time zone > PDST, the equinox is at 2:59 pm Wed 20 March 2019. The full moon is about 4 > hours later at 6:43 pm. Why is this Sunday not Easter and Friday not Good > Friday. What about the Passover. It is also a month later. I know setting > the date of Easter was the problem that inspired astronomy but this year > the scientific data and the religious credo do not seem to agree. > > > > Where have I been mislead? (other than finding silly girls posing as > sundials) > > > > Roger Bailey > > Walking Shadow Designs > > N 48.669°, W 123.403° > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > -- Cell +1 778 837 5771 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Roger, https://www.scientificamerican.com/article/how-the-moon-affects-the-date- of-easter/ This article seems to cover your point. Mike In message , Roger writes I always thought Easter Sunday was on the first Sunday after the first full moon after the spring equinox. This year at my location, time zone PDST, the equinox is at 2:59 pm Wed 20 March 2019. The full moon is about 4 hours later at 6:43 pm. Why is this Sunday not Easter and Friday not Good Friday. What about the Passover. It is also a month later. I know setting the date of Easter was the problem that inspired astronomy but this year the scientific data and the religious credo do not seem to agree. Where have I been mislead? (other than finding silly girls posing as sundials) Roger Bailey Walking Shadow Designs N 48.669°, W 123.403° --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- Mike Isaacs --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
dear Roger, The computation of Easter is a little bit complex, it follows some canonical rules. There is an astronomical equinox but the canonical equinox is always the march 21. I have notice from the ephemeris that this year the astronomic full moon is on the march 21 (1:43 UT), that is in the same date of the canonical equinox. Someone says that it should be calculate in Rome, others in Jerusalem, anyway it is wrong because the reference is the canonical full moon and it is calculated with the epact, that is the moon's age at January 1. Clavius worked on calendar reform and he wrote the epact for 4000 years. This year the epact is 24. This means I have to come back 24 days to find a canonical new moon, that is december 8. Now I have calculate the spring new moon adding 30, 29, 30, 29 days. This rule needed to approximate the lunar cycle of about 29 and half. Adding 30 + 29 + 30 days I get march 7, than I have to add 13 days to get the canonical full moon and I get march 20, that is one day before the canonical equinox. For this reason the rule adds other 29 days reaching april 18, so Easter is on april 21. To get the full moon from the new moon the rule adds 13 days and not 14.76 because it starts from the observation of the first lunar sickle, that is about 30 hours later the astronomical new moon. These are the canonical rules and they differ from the astronomical abservations because the aim was to avoid complex and contestable observations, keeping the approximation as small as possible. Sometimes the rules create curious arrangement like this year: the canonical full moon of march is one day before the canonical equinox while the astronomical full moon is one day after the astronomical equinox. There also are ecceptions, for example if the canonical full moon is on april 21 and it is saturday, Easter is not on sunday 22 but on sunday 29. Someone says because in the first case the Catholic Easter overlap Passoverr but the reason is to avoid to celebrate the resurrection in the same days of the death of Christ (Coyne, G. V., Michael A. Hoskin, and O. Pedersen. Gregorian Reform of the Calendar Proceedings of the Vatican Conference to Commemorate its 400th Anniversary, 1582-1982, 1983). These infos come from the book of Piero Tempesti, Il calendario e l'orologio (the calendar and the timepiece), 2006. Tempesti deeply analyze this matter and I have summarized what Bepi De Donà recently exposed on the italian mailing-list of gnomonics about this topic. ciao Fabio Il 20/03/2019 05:00, Roger ha scritto: I always thought Easter Sunday was on the first Sunday after the first full moon after the spring equinox. This year at my location, time zone PDST, the equinox is at 2:59 pm Wed 20 March 2019. The full moon is about 4 hours later at 6:43 pm. Why is this Sunday not Easter and Friday not Good Friday. What about the Passover. It is also a month later. I know setting the date of Easter was the problem that inspired astronomy but this year the scientific data and the religious credo do not seem to agree. Where have I been mislead? (other than finding silly girls posing as sundials) Roger Bailey Walking Shadow Designs N 48.669°, W 123.403° --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- Fabio Savian fabio.sav...@nonvedolora.it www.nonvedolora.eu Paderno Dugnano, Milano, Italy 45° 34' 9'' N, 9° 9' 54'' E, UTC +1 (DST +2) --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Equinox, Full Moon and Easter
I would like to thank all that responded to my simple question. My intent was to use the Socratic method of “asking and answering questions to stimulate critical thinking and to draw out ideas and underlying presuppositions.” I learned long ago not to ask a question unless I knew the answer. My hypothesis is there is a human need to celebrate the joy of the coming of spring, a natural time of rebirth and growth due to longer days and more direct sunlight. As usual this natural need was co-opted, codified and enforced by religious and civil authorities. Now we have better methods based on better data from precise observations with better mathematics and astronomical science. Who do you believe. The codification by civil and religious authorities is necessary for defining Easter Sunday, Good Friday, the Passover etc. Science does a better job defining the equinox, the solstices and the seasons My reference on this topic is “Sun in the Church” by J L Heilbron. Regards, Roger Bailey From: Roger Sent: March 19, 2019 9:00 PM To: sundial@uni-koeln.de Subject: Equinox, Full Moon and Easter I always thought Easter Sunday was on the first Sunday after the first full moon after the spring equinox. This year at my location, time zone PDST, the equinox is at 2:59 pm Wed 20 March 2019. The full moon is about 4 hours later at 6:43 pm. Why is this Sunday not Easter and Friday not Good Friday. What about the Passover. It is also a month later. I know setting the date of Easter was the problem that inspired astronomy but this year the scientific data and the religious credo do not seem to agree. Where have I been mislead? Roger Bailey Walking Shadow Designs N 48.669°, W 123.403° --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Yes, as was mentioned, I too have heard that, for determining Easter, they use March 21 as the equinox date. As for Passover, what I heard was that that used to be part of the Easter calculation, but was dropped by the Catholic Church. ...but that the Eastern Orthodox Church still uses Passover when reckoning Easter. Michael Ossipoff On Wed, Mar 20, 2019 at 12:00 AM Roger wrote: > I always thought Easter Sunday was on the first Sunday after the first > full moon after the spring equinox. This year at my location, time zone > PDST, the equinox is at 2:59 pm Wed 20 March 2019. The full moon is about 4 > hours later at 6:43 pm. Why is this Sunday not Easter and Friday not Good > Friday. What about the Passover. It is also a month later. I know setting > the date of Easter was the problem that inspired astronomy but this year > the scientific data and the religious credo do not seem to agree. > > > > Where have I been mislead? (other than finding silly girls posing as > sundials) > > > > Roger Bailey > > Walking Shadow Designs > > N 48.669°, W 123.403° > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Dear Roger, I note that you say: > My reference on this topic is The Sun in > the Church by J L Heilbron. He is pretty sound on this and, as early as page 3, notes that the time of the equinox and the time of full moon depend where you are on the planet. He adds, "as, of course does Sunday". If everyone used the Julian Date then they might all agree on the instant of the equinox and the instant of full moon but it seems most unlikely that they would have similar agreement as to what is meant by "Sunday". It takes 48 hours from the start of a given Sunday, just to the west of the International Date Line, to the end of the same Sunday, just to the east of the Line. Fabio has pointed out that Rome and Jerusalem have been suggested as candidate places for defining a Canonical Sunday. I too have read this but I don't know where the supposed primary source is. I think Fabio's explanation is the most plausible. In essence, you define an algorithm (albeit one that is a bit suspect) and impose a kind of ANSI Standard Easter :-) As a former colleague once told me: "The great thing about having Standards is that there are so many of them." You are one of the most-westerly subscribers to this list so I think a Bailey-Standard Easter would be worth lobbying for. You might thereby become a noted Holy Man. Be careful! Very best wishes Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Dear Frank, ... ANSI Standard Easter, I missed it, I hope none of the international authorities for the standards read this mailing-list :-) Even Gauss took care of it but his algorithm doesn't manage some exceptions. For those interested in the matter: Algorithm to calculate the date of Easter, by Spencer Jones, from his book General Astronomy, pages 73-74, edition of 1922. Published again in the Journal of the British Astronomical Association, vol. 88, page 91, december 1977. Here it is reported that the algorithm was defined on 1876 and it appeared in the Butcher's Ecclesiastical Calendar. Unlike the algorithm of Gauss, this hasn't exceptions and it runs for the Gregorian Calendar, starting from 1583. The limits of the dates are march 22 and april 25. The dates of Easter have a cycle of 5,700,000 years. The most frequently date is april 19. Example for 2019: A=5, B=20, C=19, D=5, E=0, F=1, G=6, H=29, J=4, K=3, L=1, M=0, N=4, P=20 N=4 that is april, P+1=21 The Orthodox Easter follows the Julian Calendar, the algorithm is: The cycle of the dates of the Julian Easter is 532 years. Example for 2019: A=3, B=3, C=5, D=20, E=4, F=4, G=14 N=4 april, G+1=15, in the Gregorian Calendar 15+13=28 ciao Fabio Il 21/03/2019 15:35, Frank King ha scritto: Dear Roger, I note that you say: My reference on this topic is The Sun in the Church by J L Heilbron. He is pretty sound on this and, as early as page 3, notes that the time of the equinox and the time of full moon depend where you are on the planet. He adds, "as, of course does Sunday". If everyone used the Julian Date then they might all agree on the instant of the equinox and the instant of full moon but it seems most unlikely that they would have similar agreement as to what is meant by "Sunday". It takes 48 hours from the start of a given Sunday, just to the west of the International Date Line, to the end of the same Sunday, just to the east of the Line. Fabio has pointed out that Rome and Jerusalem have been suggested as candidate places for defining a Canonical Sunday. I too have read this but I don't know where the supposed primary source is. I think Fabio's explanation is the most plausible. In essence, you define an algorithm (albeit one that is a bit suspect) and impose a kind of ANSI Standard Easter :-) As a former colleague once told me: "The great thing about having Standards is that there are so many of them." You are one of the most-westerly subscribers to this list so I think a Bailey-Standard Easter would be worth lobbying for. You might thereby become a noted Holy Man. Be careful! Very best wishes Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- Fabio Savian fabio.sav...@nonvedolora.it www.nonvedolora.eu Paderno Dugnano, Milano, Italy 45° 34' 9'' N, 9° 9' 54'' E, UTC +1 (DST +2) --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Please unsubscribe me On Fri, Mar 22, 2019 at 5:00 AM fabio.sav...@nonvedolora.it < fabio.sav...@nonvedolora.it> wrote: > Dear Frank, > > ... ANSI Standard Easter, I missed it, I hope none of the international > authorities for the standards read this mailing-list :-) > > Even Gauss took care of it but his algorithm doesn't manage some > exceptions. > > For those interested in the matter: > Algorithm to calculate the date of Easter, by Spencer Jones, from his book > General Astronomy, pages 73-74, edition of 1922. > Published again in the Journal of the British Astronomical Association, > vol. 88, page 91, december 1977. > Here it is reported that the algorithm was defined on 1876 and it appeared > in the Butcher's Ecclesiastical Calendar. > Unlike the algorithm of Gauss, this hasn't exceptions and it runs for the > Gregorian Calendar, starting from 1583. > > The limits of the dates are march 22 and april 25. > The dates of Easter have a cycle of 5,700,000 years. > The most frequently date is april 19. > > Example for 2019: > A=5, B=20, C=19, D=5, E=0, F=1, G=6, H=29, J=4, K=3, L=1, M=0, N=4, P=20 > N=4 that is april, P+1=21 > > The Orthodox Easter follows the Julian Calendar, the algorithm is: > > > The cycle of the dates of the Julian Easter is 532 years. > > Example for 2019: > A=3, B=3, C=5, D=20, E=4, F=4, G=14 > N=4 april, G+1=15, in the Gregorian Calendar 15+13=28 > > ciao Fabio > > > Il 21/03/2019 15:35, Frank King ha scritto: > > Dear Roger, > > I note that you say: > > > My reference on this topic is The Sun in > the Church by J L Heilbron. > > He is pretty sound on this and, as early > as page 3, notes that the time of the > equinox and the time of full moon depend > where you are on the planet. He adds, > "as, of course does Sunday". > > If everyone used the Julian Date then > they might all agree on the instant of > the equinox and the instant of full > moon but it seems most unlikely that > they would have similar agreement as > to what is meant by "Sunday". > > It takes 48 hours from the start of a > given Sunday, just to the west of the > International Date Line, to the end of > the same Sunday, just to the east of > the Line. > > Fabio has pointed out that Rome and > Jerusalem have been suggested as > candidate places for defining a > Canonical Sunday. I too have read > this but I don't know where the > supposed primary source is. > > I think Fabio's explanation is the > most plausible. In essence, you > define an algorithm (albeit one > that is a bit suspect) and impose > a kind of ANSI Standard Easter :-) > > As a former colleague once told me: > "The great thing about having Standards > is that there are so many of them." > > You are one of the most-westerly > subscribers to this list so I think > a Bailey-Standard Easter would be > worth lobbying for. > > You might thereby become a noted > Holy Man. Be careful! > > Very best wishes > > Frank > > ---https://lists.uni-koeln.de/mailman/listinfo/sundial > > -- > Fabio savianfabio.sav...@nonvedolora.itwww.nonvedolora.eu > Paderno Dugnano, Milano, Italy > 45° 34' 9'' N, 9° 9' 54'' E, UTC +1 (DST +2) > > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Dear Fabio, I think the Spencer-Jones algorithm is now widely accepted as defining when Easter will be observed (by both the Roman Catholic Church and the Anglican Church for the foreseeable future). What is interesting is just how often it produces the same date as the naive rule of 'the first Sunday after the first full moon after the equinox'. This year is clearly an exception because the algorithm and the naive rule give different answers. Do you know how often the algorithm and the naive rule differ? You are allowed to choose your own defintion of 'Sunday'! Ciao Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Dear Frank the replay at your question is not easy. I see some ways to find it: - one is exhaustive, few lines of software could check how many times the naive rule is verified in the whole cycle. It isn't very smart but it may be useful to verify the other points - to disassemble the algorithm finding where and when it intervenes to shift the date - reformulate an approach to find when the sunday overlap the canonical full moon but I think I would find myself in the previous point, with the formulation of epacts of Clavius - to consult the book of Tempesti where there are many kind of tables and considerations on this matter, may be the answer is already written. At first I think to follow the last point, unluckily I lent the book and it come back to me in the next days, I'll come back on the matter as soon as the book returns to my hands. Yesterday I went to sleep thinking about the 3rd point, obviously I didn't solve my question but I dreamed my 'Sunday': I was going to an heliodrome with an ice cream :-) ciao Fabio Il 22/03/2019 17:02, Frank King ha scritto: Dear Fabio, I think the Spencer-Jones algorithm is now widely accepted as defining when Easter will be observed (by both the Roman Catholic Church and the Anglican Church for the foreseeable future). What is interesting is just how often it produces the same date as the naive rule of 'the first Sunday after the first full moon after the equinox'. This year is clearly an exception because the algorithm and the naive rule give different answers. Do you know how often the algorithm and the naive rule differ? You are allowed to choose your own defintion of 'Sunday'! Ciao Frank -- Fabio Savian fabio.sav...@nonvedolora.it www.nonvedolora.eu Paderno Dugnano, Milano, Italy 45° 34' 9'' N, 9° 9' 54'' E, UTC +1 (DST +2) --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
Dear Fabio, Many thanks for your follow-up. I look forward to hearing more when you get your book back. I wonder how many people know how difficult it is to define 'Sunday'!! It is possible to define Sunday so that, sometimes, half the planet has Easter after one full moon and the other half of the planet has Easter after the next full moon! Ciao Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equinox, Full Moon and Easter
For that matter, why are we even still using the Roman-Gregorian Calendar? (Roman months with Gregorian leap-year-rule) . There are many alternative calendar proposals, but, among all of those that keep weeks, the minimal, most convenient and easy calendar is a WeekDate calendar: . The weeks of the year are numbered, and the date consists of the week-number and the day-of-the-week. . The most un-arbitrary WeekDate proposal, is South-Solstice WeekDate: . Today’s date, in South-Solstice WeekDate, is: . 13 Sa . …Saturday of the 13th week of the calendar-year that started with the Monday that started nearest to the South-Solstice. - Of course, like the French-Republican Calendar of the 18th century, that year-start rule depends on an annual astronomical observation (or orbital-calculation). . An arithmetical rule is considered more convenient. For example, our Gregorian leapyear-rule is based on an arithmetical approximation to the March equinox. . South-Solstice WeekDate can also be defined with an arithmetical year-start rule, based on an arithmetical approximation to the South-Solstice, based on an assumption that a South-Solstice occurs exactly every 365.2422 days, starting from (say) the actual South-Solstice of 2017. . So, that approximated South-Solstice is used instead of the actual South-Solstice. The calendar year starts with the Monday that starts closest to the approximated South-Solstice defined in the previous paragraph. There’s a WeekDate calendar that’s actually in wide international use by governments and companies: . The International Standards Organization WeekDate calendar (ISO WeekDate Calendar): . The calendar year starts with the Monday closest to Gregorian January 1st. . A bit arbitrary, and dependent on the old Roman-Gregorian Calendar, but it’s already in wide use, and its software is already widely-distributed. . I’ve found that many people prefer (at least as a first reform-proposal) ISO WeekDate to South-Solstice WeekDate, because of the familiarity of Gregorian January 1st as the basis for year-start. -- Both of those WeekDate proposals, South-Solstice WeekDate and ISO WeekDate, of course start every year on a Monday. With every year starting on the same day-of-the-week, then every calendar-year is identical, other than the fact that every 5th or 6th year automatically has a 53rd week. That would bring a tremendous simplicity for scheduling of annual events and holidays. For example, if desired, as come calendarists propose, Easter could be defined as a particular Sunday date, such as 13 Su or 14 Su. Always on a Sunday, and its date would be the same each year. . The day-of-the-week for a distant future appointment would never be in question, because the day-of-the-week is _part of_ the date. . With Roman-Gregorian, the day-of-the-month of course changes each day, and people usually look it up, referring to a printed or digital calendar. With a WeekDate calendar, if you know the day-of-the-week, then you know the date. For example, today the week-number has been 13 for some days, ever since last Monday, and it will remain so until next Monday. So, because yesterday was 13 F, today is 13 Sa. . Durations, too, are easier to determine with WeekDate, compared to with the Roman months. --- Someone could argue that, due to millennia of use, the Roman months tell us something about the season. But there’s nothing inherently more seasonal or natural about the Roman months. In fact, South-Solstice WeekDate gives good seasonal information without millennia of familiarity: . We’re now in week 13. At the end of week 13, we’re roughly a quarter-year after the South-Solstice, meaning that one would expect the end of week 13 to be near the Northward (March) Equinox. (…but not exact, because the calendar-year starts, not on the South-Solstice, but rather on the nearest-Monday, as specified above.) . So the South-Solstice WeekDate week-number is a rough but good indication of the solar ecliptic longitude. . Michael Ossipoff . 13 Sa (South-Solstice WeekDate Calendar) 1551 UTC --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Easter ( a bit off topic) (a bit further off!)
Frank, Can I ask if you have been in isolation for the last three years??? I thought that by now EVERYONE in the world, from Ulan Bator to John O'Groats to Podunk Ohio to Ushuaia realised that there is NO world after the Sydney 2000 olympics!!! Looks like Oxford University Press was just a bit more successful at predicting the future that we previously thought! And you thought it was just a ploy to get you to buy the next edition. But maybe, just maybe, I have been so brainwashed by our fearless political leaders that even I (who loathes the olympics with a passion) have come to believe the rhetoric. Frank, are you really telling me that there WILL (gasp, gasp) be life after 2000? That there will be an Easter in 2001??? I am not sure if you have made my day or have stressed me so much that I will need to seek psychiatric help to cope with what may well be an epiphany. John Dr John Pickard Senior Lecturer, Environmental Planning Graduate School of the Environment Macquarie University, NSW 2109 Australia Phone + 61 2 9850 7981 (work) + 61 2 9482 8647 (home) Fax + 61 2 9850 7972 (work)
