Easter Lunacy

By Walter Kish

This past March 23, most Catholics and many other Christian denominations worldwide celebrated Easter Sunday, arguably the most important date on the ecclesiastical calendar.  Of course, for the Orthodox and certain other churches, Easter doesn’t come this year until April 27.  As a youth, I always used to wonder why the date for Easter varied so much from year to year.  Even more confusing was why “Ukrainian” Easter differed from my neighbouring Catholics’ Easter sometimes by a week and sometimes by a month or more. 

My parents being not well versed in either astronomy or the complexities of ecclesiastical Easter traditions could shed little light on the matter.  It was only much later in life when I was able to do my own research that things became clearer, at least to a point.  The qualification is necessary, since as with many things involving religious beliefs, you may come to understand the how, but not necessarily the why.  Or, as my eccentric cousin Hryts would say – one should never let facts get in the way of a good tradition.

In the early years following the Crucifixion of Christ in 30 AD or thereabouts, Easter was typically celebrated on the first Sunday after the Jewish Passover, since Jesus’ famous Last Supper was in fact the ritual feast or evening Seder celebrating the start of the Jewish holy week commemorating the Israelites exodus from Egypt.  Passover always fell on a full moon, with the exact date being based on a complex calculation done by the elders of the Jewish religious council, the Sanhedrin, in Jerusalem.  The Jewish calendar is based on what is called a metonic cycle of 235 complete lunar cycles forming a larger 19 year recurring cycle.  This produced years varying in length from 353 to 385 days, with 7 of the 19 years having thirteen lunar months instead of twelve.  Needless to say, the average Christian (or Jew for that matter) would have a difficult time calculating the date of the next Passover or Easter.  Trying to do so no doubt gave rise to the current meaning of the word lunacy.

By the Fourth Century AD, the growing Christian community wanted to dissociate their link with the Jewish Passover and at the Council of Nicea in 325 AD, standardized the setting of the date of Easter based on the more scientifically rational Roman Julian Calendar.  Julius Caesar had instituted this calendar in 46 BC with a year based on 365 days with an additional day added every fourth year, called a leap year.  The Council decreed that henceforth, Easter would be celebrated on the first Sunday after the full moon after the spring equinox, unless that full moon fell on a Sunday, in which case Easter would be the following Sunday. And so for the next thousand years or so, Christians of whatever stripe had a standard and ecumenically sanctioned methodology by which they could determine when to celebrate Easter. 

Alas, astronomical and religious changes would eventually conspire to throw a monkey wrench into the Nicene solution.  The Julian Calendar, though much more in sync with the actual astronomical movements of the sun and moon, was not totally accurate, being some 11 minutes per year out of alignment with the actual progression of the astronomical solstices and equinoxes.  This meant that every 134 years, there was a one day discrepancy between the date of Easter and the corresponding phase of the moon.  The cumulative difference had grown to ten days by 1582, at which time Pope Gregory XIII decided to take action and instituted the reformed Gregorian Calendar.  The calculation of leap years was changed to more accurately reflect astronomical reality, and the year 1582 was brought back into alignment by essentially erasing ten days, with October 4, 1582 being followed the next day by October 15, 1582.

It took a while for the Gregorian Calendar to be universally adopted.  The British Empire did not adopt it until 1752.  Russia converted after the 1917 Bolshevik Revolution.  The last European country to convert was Greece in 1923.  Although all countries in the world now accept the Gregorian Calendar for civil and practical purposes, most of the Orthodox Churches of Eastern Europe refused to do so and still employ the original Julian Calendar for calculating their religious holidays as per the original Nicene declaration.  Since the Gregorian reform, the discrepancy between the Julian and astronomical calendars has grown from 10 days to thirteen which is why Orthodox Christmas is on January 7 instead of December 25.  One should keep in mind though that by 2100 AD, the cumulative difference will grow by another day and Orthodox Christmas will be celebrated on January 8^th after that date. 

Easter, not being set on a fixed day of the year, but calculated based on lunar phases, will continue to vary from year to year.  The date of Orthodox Easter, being based on Julian calendar full moon tables calculated back in 325 AD, means that it will continue to be just as difficult to answer our children’s questions on why there is such a difference between the two Easters as when I was still a kid.