When is Easter this year.

Discussion in 'The Commons' started by AnglicanAgnostic, Mar 24, 2022.

  1. AnglicanAgnostic

    AnglicanAgnostic Well-Known Member

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    Looking at our calendar I noticed that there was a full moon on the 18th March (18/3/2022:D) and there will be one on 17/4/2022. So how come, I thought, Easter Sunday is also on the 17/4/2022? Because I know that Easter Sunday is the first Sunday after the first full moon after the 21st March.
    Then it occurred to me, we in NZ are a day ahead of you in America and Europe and our full moon is on your Saturday. But is our full moon the same time as your full moon? If it's timed to the second probably not as it will be daylight where you are at the time.
    Regardless I think the ecclesiastical full moon is calculated differently to the astromical full moon.

    I'ld just like to check that you Christians are getting things right.:halo::halo:
     
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  2. Tiffy

    Tiffy Well-Known Member

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    What makes a full moon full? And can a moon become full if you can't see it during the day? A bit like "Does a falling tree make a sound if no one is there to hear it"?

    You trouble maker. :clap::laugh: So inconvenient of God to provide a moon "“to separate the day from the night and for signs, seasons and days, and to give light upon the earth”, with an eliptical orbit which slows down and speeds up, changes it's distance from the earth constantly does not take exactly 1/12 of a year to orbit the earth, and sometimes can't be seen at all or 'give any light upon it'.

    I'm afraid we are stuck with it though, for the time being at least. :laugh:
    .
     
    Last edited: Mar 25, 2022
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  3. Invictus

    Invictus Well-Known Member

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    Unfortunately, since the first 2,000 years of the Church’s calendar and liturgy developed with the northern hemisphere (and change of seasons) in mind, it is likely strictly verboten to take the existence of places like New Zealand into account today. If the Fathers didn’t know about New Zealand, it must not be important. I’m afraid the references to Lent (“spring”), and hymns mentioning snow in the middle of summer, will have to stay. /s
     
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  4. Tiffy

    Tiffy Well-Known Member

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    Precisely. God's church got on perfectly well for 1,642 years with not having to admit the existence of New Zealand. Why should it have to deal with such new fangled ideas after all that time of thinking it shouldn't exist? :laugh:

    But I think I'm mixing my threads up here, sorry.
    .
     
    Last edited: Mar 25, 2022
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  5. Invictus

    Invictus Well-Known Member

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    To be fair, even if the Fathers had known about the existence of New Zealand, they would surely not have expected it to have been inhabited. Being at the Antipodes, any unfortunate soul who found himself there would have fallen off the Earth. /s
     
  6. Tiffy

    Tiffy Well-Known Member

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    Or have been gobbled up by huge sea monsters.
     
  7. Invictus

    Invictus Well-Known Member

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    Right! Because Leviathan. /s
     
  8. ZachT

    ZachT Well-Known Member

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    As much fun as you guys seem to be having, we have the same phases of the moon as you fellas on the north side of the globe. The full moon in Wellington happens at the same moment as the full moon in Rome, Beijing and NYC. You just have the misfortune of being forced to look at the moon upside down.

    The full moon could happen on different calendar days (as it does this year), but that's not a Northern/Southern thing, that's a time zone thing. The Full Moon happens at ~7:00am on Easter Sunday in NZ, so technically that means Easter ought to be a week later in NZ, but so too for people living in Japan (~4:00am). But evidently we must all agree to go off Rome time, or GMT+0 or something.
     
  9. Tiffy

    Tiffy Well-Known Member

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    Upside down, I hadn't thought of that. What about the man in the moon. Is that upside down, down under or just indiscernable as a face?
    .
     
  10. Rexlion

    Rexlion Well-Known Member

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    Everything revolved around the Holy Land, you know. ;)

    You folks down under can fix this full moon problem, though. On Saturday night, go outside and drop your drawers, and there will be a full moon. :laugh:
     
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  11. Botolph

    Botolph Well-Known Member

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    March Equinox 2022 - March 20: 15.33
    For Simplicity East is calculated as the first Sunday after the first full moon after March 21.
    Full Moons in 2022 are Mon Jan 17 , Wed Feb 16, Fri Mar 18, Sat Apr 16, Mon May 16.

    So the first Sunday after the first full moon after the 21st of March is Sunday the 17th of April, Easter Day.

    Now New Zealand is a far advanced Country and so the New Moon in Question will happen in New Zealand at 6.55 am on the 17th of April. At that time it will be 8.55 pm on the 16th of April in Jerusalem, 6.55 pm on the 16th of April in Rome, 5.55 pm on the 16th of April in London, 1.55 pm on the 16th of April in New York, and 7.55 am on the 16th of April in Hawaii.

    So you are correct in assessing that the rest of the world is holding New Zealand back again. If the formula was used according to local time the you would be celebrating Easter on the 24th of April, which coincidentally is Eastern Orthodox Easter (of Pascha as they describe it).

    I am not sure whose date is being used to calculate the full moon, but given then is only and hour between UTC and Rome, it is likely to be one of them.
     
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  12. Shane R

    Shane R Well-Known Member

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    I tried using the rather complicated formula in the front of the 1662 BCP -find the golden number and the letter and all that- and arrived at the date of April 11, which is not even a Sunday. The maths never were my strong subject.
     
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  13. Invictus

    Invictus Well-Known Member

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    This is just a guess, but I’m not sure the 1662 instructions were applicable after the year 1900. That may be the problem.
     
  14. Tiffy

    Tiffy Well-Known Member

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    According to the Prayer Book, the old table works up to 2100. After that for the next following century from 2100 till the year 2199 inclusive, add to the current year its Fourth Part, and also the number 5, and then divide by 7, and proceed as in the last Rule.
    Note, That in all Bissextile or Leap-Years, the Letter found, as above, will be the Sunday Letter from the intercalculated Day exclusive, to the End of the Year.
    Isn't that clear enough for everyone? :laugh: Who ever said the BCP is difficult to understand?
    I wonder if we are in a Bissextile year this year though? :biglaugh: Do we suppose the male only-trans phobic- fundies, will be able to cope with being stuck in a whole year like THAT?
    Bissextilely uncomfortable or what? :whistle:

    Truly not only does God move in mysterious ways. Easter does too. :hmm:I've never even tried to work it out for myself. I assume, (in a very traditionally medievil way), that someone higher up than me in the church knows how to do it and so I just take their word for it and turn up for church and find its Easter Day. For me its 'fixed' - always exactly two days after Good Friday. :unsure:
    .
     
    Last edited: Mar 28, 2022
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  15. Botolph

    Botolph Well-Known Member

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    I have just had a go with the Golden Number from the BCP and it works for me.

    Golden Number Method

    ((Year + 1)/19-Rounddown(Year+1)/19)*19

    ((2022 + 1)/19 - Rounddown(2022+1)/19)*19 =9

    In the table it tells me that IX = April 16, so Easter falls on the Sunday after April 16, namely April 17 2022.

    Alternative method

    shout out 'Hey Google, when is Easter this year?'

    Bisextile Years
    These are years where the number of days includes to sixes, as in 366, as against the more normative 365.
     
  16. AnglicanAgnostic

    AnglicanAgnostic Well-Known Member

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    There is another presumably different formula in my BoCP for the years 2199 to 2299. But I'll worry about that when the time comes. :rolleyes:

    And they would have been correct. Maori didn't inhabit NZ till 1000AD, +/- , 200 years or so.

    Thanks Botolph but could you explain your formula a bit more? Is the "-" a minus or a punctuation mark. I take it rounddown means taking a number down to the next integer and if so should there be two or even three rounddowns?

    I understand maths, maybe not to Phd level though.
     
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  17. Botolph

    Botolph Well-Known Member

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    ((Year + 1)/19-Rounddown(Year+1)/19)*19

    Step 1: (Year + 1)/19 is the Year plus 1 divided by 19. In this case 2022+1=2023 divided by 19 = 106.473684210526
    Step 2: Rounddown(Year+1)/19). In this case this is simply Part a as an integer, 106.
    Step 3: Step 1 - Step 2, which is the remainder. 0.473684210526
    Step 4: Multiply Step 3 by 19 to return it to the integer. In this case 9.

    Look up the table and 9 means April 16. The Sunday after April 16 is April 17.

    Hence my preference for the alternative method I described!
     
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  18. Tiffy

    Tiffy Well-Known Member

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    But WHY does it work? That's what I'd like to know.
    .
     
  19. AnglicanAgnostic

    AnglicanAgnostic Well-Known Member

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    Ahh it all makes sense now. I understood your formula but thought it might be wrong as I didn't appreciate that the .473684210526 bit was the important part. Also there was no suggestion the [ ((Year + 1)/19-Rounddown(Year+1)/19) ] part, times 19 would give you an integer. I'm sure the average person would suspect that 0.473684210526 x 19 wasn't an integer and I was expecting another rounddown statement, but no my Casio says 9.

    Me too.


    Time to brush up on my algebra.
     
  20. Botolph

    Botolph Well-Known Member

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    Official Theory
    The Easter cycle groups days into lunar months, which are either 29 or 30 days long. There is an exception. The month ending in March normally has thirty days, but if 29 February of a leap year falls within it, it contains 31. As these groups are based on the lunar cycle, over the long term the average month in the lunar calendar is a very good approximation of the synodic month, which is 29.53059 days long. There are 12 synodic months in a lunar year, totaling either 354 or 355 days. The lunar year is about 11 days shorter than the calendar year, which is either 365 or 366 days long. These days by which the solar year exceeds the lunar year are called epacts (Greek: ἐπακταὶ ἡμέραι, translit. epaktai hēmerai, lit. "intercalary days"). It is necessary to add them to the day of the solar year to obtain the correct day in the lunar year. Whenever the epact reaches or exceeds 30, an extra intercalary month (or embolismic month) of 30 days must be inserted into the lunar calendar: then 30 must be subtracted from the epact. Charles Wheatly provides the detail:

    "Thus beginning the year with March (for that was the ancient custom) they allowed thirty days for the moon [ending] in March, and twenty-nine for that [ending] in April; and thirty again for May, and twenty-nine for June &c. according to the old verses:​

    Impar luna pari, par fiet in impare mense;
    In quo completur mensi lunatio detur.

    "For the first, third, fifth, seventh, ninth, and eleventh months, which are called impares menses, or unequal months, have their moons according to computation of thirty days each, which are therefore called pares lunae, or equal moons: but the second, fourth, sixth, eighth, tenth, and twelfth months, which are called pares menses, or equal months, have their moons but twenty nine days each, which are called impares lunae, or unequal moons."
    — Wheatly 1871, p. 44​

    Thus the lunar month took the name of the Julian month in which it ended. The nineteen-year Metonic cycle assumes that 19 tropical years are as long as 235 synodic months. So after 19 years the lunations should fall the same way in the solar years, and the epacts should repeat. However, 19 × 11 = 209 ≡ 29 (mod 30), not 0 (mod 30); that is, 209 divided by 30 leaves a remainder of 29 instead of being a multiple of 30. So after 19 years, the epact must be corrected by one day for the cycle to repeat. This is the so-called saltus lunae ("leap of the moon"). The Julian calendar handles it by reducing the length of the lunar month that begins on 1 July in the last year of the cycle to 29 days. This makes three successive 29-day months.[e] The saltus and the seven extra 30-day months were largely hidden by being located at the points where the Julian and lunar months begin at about the same time. The extra months commenced on 1 January (year 3), 2 September (year 5), 6 March (year 8), 3 January (year 11), 31 December (year 13), 1 September (year 16), and 5 March (year 19).[33][34] The sequence number of the year in the 19-year cycle is called the "golden number", and is given by the formula
    GN = (Y + 1) mod 19
    That is, one is added to year number Y in the Christian era, the sum is divided by 19; the remainder is the golden number, with a remainder of 0 indicating the golden number is 19.

    The paschal or Easter-month is the first one in the year to have its fourteenth day (its formal full moon) on or after 21 March. Easter is the Sunday after its 14th day (or, saying the same thing, the Sunday within its third week). The paschal lunar month always begins on a date in the 29-day period from 8 March to 5 April inclusive. Its fourteenth day, therefore, always falls on a date between 21 March and 18 April inclusive, and the following Sunday then necessarily falls on a date in the range 22 March to 25 April inclusive. In the solar calendar Easter is called a moveable feast since its date varies within a 35-day range. But in the lunar calendar, Easter is always the third Sunday in the paschal lunar month, and is no more "moveable" than any holiday that is fixed to a particular day of the week and week within a month.​

    My Version
    The Lunar year repeats after 19 years, against the Gregarian Calendar. This means that the Full Moon falls around the same day every 19 years. The Sunday after the first Full Moon after the 21st of March is the date for Easter. The formular generates a number between 0 and 18. That means that there are nineteen days on which the Pascal Full Moon can fall.
    GoldenNumberPascalFullMoon.jpg

    The are seven days following a full moon on which Easter can fall, so there are there are seemingly 26 dates on which Easter can fall, all sundays!, and all exactly 3 days after Good Friday!

    The earliest date for Easter (rare though it is) is the 22nd of March - happened in 1818, and happens next in 2285. The last day Easter can fall is April 25 (also rare), last falling on this date in 1943 and will next do so in 2038. That is a spread of 35 dates. So I didn't get that correct.

    Full Moon Dates
    March 21
    March 22
    March 24
    March 25
    March 27
    March 29
    March 30
    April 1
    April 2
    April 4
    April 5
    April 7
    April 9
    April 10
    April 12
    April 13
    April 15
    April 17
    April 18

    7 days in March and 12 Days in April, from March 21 to April 18 - a spead of 28 days, and add the seven days of a week on which Easter might fall on the Sunday followinbg and we have 35 days in the range.

    What I don't really get is why the full moon can not fall on March 23, 26, 28, 31 nor on April 3, 6, 8, 11, 14, 16.

    I think I will put that down to 'now we see in a mirror dimly'. ​