Easter Sunday is by far the most important date of the Christian calendar. But why does it move around so strangely? For example, we celebrated Easter on April 23 in the year 2000 but on March 23 in 2008 – a full month difference! Also, not everyone uses the same date: in 2016 the Western churches (both Roman Catholic and Protestant) celebrated Easter on March 27 while Eastern Orthodox churches celebrated on May 1 – yet in 2017 Easter falls on April 16 for everyone! Why isn’t the date of Easter better behaved? Looking at this weird variability, one might be tempted to assume it’s because we’re all just ‘winging’ it! Quite the contrary, we actually know the exact day of the year when the first Easter occurred – but on the Jewish (lunar) calendar! And that’s why our annual celebration jumps around on our (solar) calendar.
It takes about 29½ days for the moon to rotate around the earth and about 365¼ days for the earth to orbit the sun. All modern societies today use the Gregorian solar calendar (introduced in 1582) whose 12 months normally add up to 365 days and then adds a “leap day” every fourth year. The beginning of the year for this solar calendar is tied to the winter solstice. Christmas has a “fixed” date because December 25th was arbitrarily chosen as the day to celebrate Christ’s birth.
Ancient peoples used lunar calendars where the months were defined by the phases of the moon. The Jewish version employs 12 months of 29 or 30 days (with three months of changeable length) and periodically adds an extra month so that festivals don’t drift around the seasons of the year. The first month of the Jewish year (Nissan) is tied to the first appearance of the new moon following the spring equinox (normally March 20). God told the Jews to begin the Passover observance at sunset on the 14th day of Nissan (Leviticus 23:5) and all other Jewish festivals were also tied to their lunar calendar. Since we know from the Gospels that Jesus’ crucifixion was at Passover it was natural for the early Christians to use the Jewish calendar to fix the date to celebrate Easter.
But, that wasn’t the ‘no-brainer’ that one might think. Christians were split on whether to always celebrate Easter per the date of the Jewish Passover OR always on a Sunday – you couldn’t have it both ways. This was a major controversy for a couple centuries! Anyway, after the Emperor Constantine legalized Christianity in 313 AD, one of his actions was to convene the first-ever ‘ecumenical council’ of the church to address some festering sources of conflict. One of their most important assignments was to standardize the date of Easter, which they agreed should hereafter be celebrated on the first Sunday following the first full moon that occurs on or after the spring equinox (whew!). This kept it close to Passover and also ensured it would be a Sunday. So that finally settled things, right?
Unfortunately not! Though both the Eastern and Western branches of Christianity use this same formula, the West later adopted the Gregorian calendar and the East retained the older Julian calendar. There’s also a difference in how the date of the equinox is determined, and the end result is that the Eastern and Western churches usually celebrate Easter on different dates. There has been sporadic talk about trying to ‘reform’ the date of Easter to eliminate the present variability, but getting everyone on board with such a change in long-standing traditions isn’t likely to happen any time soon.
All of this has focused on the calendar date on which we celebrate Easter. But this says nothing about the actual date of the first Easter (the Sunday when Jesus rose from the grave) – for that we need to know the year, and that isn’t precisely known. Based on the clues found in the Bible, the majority of scholars believe it was April 7, 30 AD, but a strong minority also favors April 3, 33 AD.
Of course, we obviously shouldn’t lose sight of the fact that exactly when we celebrate Easter is totally inconsequential compared to what Easter means to the human race. The miracle of Jesus’ resurrection is something we should celebrate every Sunday (at the very least!)