Western Easter and Pascha

[silouanathonite]

My girlfriend asked why the dates are different. Does anyone have an explanation I can give to her. It should be very simple and not lengthy. I don't want to overwhelm her at the moment. I allow her to ask questions when she is ready. Thanks in advance for your help.

P.S.--> Lengthy stuff can also be included for my own benefit.

 

[Matrona]

We calculate Pascha based on the Vernal Equinox as it occurs on the Julian calendar, which occurs in early April on the civil calendar, rather than calculating it by the physical Vernal Equinox which is March 20/21 and marked as such on the Gregorian calendar.

For instance, if the first full moon occurs after the Gregorian Vernal Equinox but before Julian Vernal Equinox, it can fling Pascha five weeks after Easter since Pascha must wait for another full moon to come around.

 

[Lukaris]

The year was calculated at its present length in the civil calendar & adopted by Pope Gregory in the late 16th century replacing a slightly different calculation of the old Julian calendar. This was not adopted in England & America til the mid 18th century. The Orthodox Church sticks to the old calendar for Pascha (& some jurisdictions Christmas too) . Both calendars use the same lunar calculating process for Pascha but since each year is different, Pascha usually falls on different Sundays.

 

[silouanathonite]

I was thinking of giving this explanation to her. I just wanted to see if there are any mistakes in there. I got it from a website. It seems pretty accurate.


Western churches use the Gregorian Calendar to calculate the date of Easter and Eastern Orthodox churches use the Julian Calendar. This is partly why the dates are rarely the same.
Easter and its related holidays do not fall on a fixed date in either the Gregorian or Julian calendars, making them moveable holidays. The dates, instead, are based on a lunar calendar very similar to the Hebrew Calendar.
The Eastern Orthodox Church not only maintains the date of Easter based on the Julian Calendar which was in use during the First Ecumenical Council of Nicea in 325 AD, but also according to the actual, astronomical full moon and the actual vernal equinox as observed along the meridian of Jerusalem. This complicates the matter, due to the inaccuracy of the Julian calendar, and the 13 days that have accrued since 325 AD. This means, in order to stay in line with the originally established (325 AD) vernal equinox, Orthodox Easter cannot be celebrated before April 3 (present day Gregorian calendar), which was March 21 in 325 AD. Additionally, in keeping with the rule established by the First Ecumenical Council of Nicea, the Eastern Orthodox Church adhered to the tradition that Easter must always fall after the Jewish Passover, since the death, burial and Resurrection of Christ happened after the celebration of Passover. Eventually the Orthodox Church came up with an alternative to calculating Easter based on Passover, and developed a 19-year cycle, as opposed to the Western Church 84-year cycle.

 

[Mary of Bethany]

Man, this stuff makes my head spin!

 

[silouanathonite]

You're not kidding, I still don't get the whole calendar thing.

 

[fuerein]

I get the calendar, in as much as I walk over to the wall where it hangs and look at it and can read it. Beyond that I try not to think about it. Gives me headaches.

 

[Asinner]

We calculate Pascha based on the Vernal Equinox as it occurs on the Julian calendar, which occurs in early April on the civil calendar, rather than calculating it by the physical Vernal Equinox which is March 20/21 and marked as such on the Gregorian calendar.

For instance, if the first full moon occurs after the Gregorian Vernal Equinox but before Julian Vernal Equinox, it can fling Pascha five weeks after Easter since Pascha must wait for another full moon to come around.

Good thing you emphasized that it occurs on the Julian calendar, otherwise it might be a bit confusing.

Love,
Christina

 

[buzuxi02]

Both the Orthodox and the jews use a 19 year cycle known as the metonic cycle to calculate the Pascha. In accordance with Nicea Orthodox Pascha Sunday can never fall on or before the first day Passover since Pascha can only fall AFTER the first full moon while Jewish passover falls on the full moon.

Here is an explanation of the metonic cycle:

Metonic cycle: Definition and Much More from Answers.com

And a further explanation of the revised metonic cycle (callipic cycle)

Metonic cycle