Dear DOD,
I thought Easter and Passover coincided, but this year Passover is not until 4/22. How are the movable feasts determined?
Curious, and Curious-er,
Thank you,
Cynthia Juvinall
Dear Cynthia,
Your answer lies in the leap between whether the universe behaves like a machine or like an organism. Most of us of certain years grew up in the comfort of a worldview, determined by Newtonian physics, where everything was orderly and tidy.
That’s not the way it works. I checked with a COS member who is a navigation engineer at JPL/NASA and discovered that it takes 365.242 days for Earth to orbit the sun and it takes the moon 29.53 days to orbit Earth. Combining these two separate ways of measuring time makes the creation of a calendar a challenge.
The New Testament reports that Jesus’s death and resurrection occurred historically at the same time as the Jewish celebration of Passover. The date of Passover occurs on the Jewish calendar month Nisan on the 15th day, which is always the full moon. (The story goes that when the Jewish people escaped their slavery in Egypt, they did it under the cover of darkness and needed the light of the full moon.) Because the Jewish calendar is a lunar-solar calendar, the intersecting imprecisions of the lunar and solar orbits necessitate calendar adjustments to be made periodically. For the Jewish calendar, leap months, called Second Adar, are added seven times during a 19-year period. (Adar is the last month of the Jewish year.) By comparison, the Gregorian calendar (established in 1582 CE) adjusts by adding one day every four years. Since this year (2024 CE) is a leap year for the Jewish calendar, the added month pushed Passover three weeks beyond Western Christendom’s Easter.
Calendaring the date of Easter brings new complications. “Traditionally,” Easter falls on the first Sunday following the first full moon after the vernal equinox.
Our 1979 Book of Common Prayer includes this:
Easter Day is always the first Sunday after the full moon that falls on or after March 21. It cannot occur before March 22 or after April 25.
This puts us in sync with the churches of Western Christendom. March 21 is an arbitrary fixed date for the vernal equinox, as determined by the council of Nicaea 325 CE. Eastern Christendom, however, uses the Julian calendar, which uses the actual astronomical date for the vernal equinox, which varies from year to year. This means that often, Western and Eastern churches do not celebrate Easter on the same Sunday. Eastern Christendom will celebrate Easter this year on May 5.
Fun fact: The Gregorian calendar, which uses the birth of Jesus of Nazareth as the point from which dates in the future are counted, and dates in the past are counted, has become the almost universal secular calendar in our modern-day world. The holdout countries that do not use the Gregorian calendar are Ethiopia, Nepal, Iran, and Afghanistan.
Another fun fact: The last time the March equinox was on March 21 was in 2007. It won’t happen again until 2101. There is no March 21 equinox in the mainland U.S. in the 21st century!
Yet another: Eastern and Western dates for Easter won’t be on the same Sunday again until 2034 (the last time having been in 2017.)
Hope this helps.
Dear Old Dad (DOD)
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