Since the beginning of the 20th century, a proposal to change Easter to a fixed holiday rather than a movable one has been widely circulated, and in 1963 the Second Vatican Council agreed, provided a consensus could be reached among Christian churches.
Planning a trip in a high touristic season is hard.
Everything is expensive and expected to be crowded.
And by full moon it does not mean the astronomical full moon but the "ecclesiastical moon," which is based on tables created by the church.
These constructs allow the date of Easter to be calculated in advance rather than determined by actual astronomical observances, which are naturally less predictable.
Like every serious procrastinator, I immediately dived into this quest. Wikipedia defines Easter as a moveable feast because it follows lunar cycles instead of Gregorian or Julian calendars.
I’m not going into historical details, but ancient people have determined that it comes to be the first Sunday after the full moon that occurs after the spring equinox.
This division between the Eastern and Western Churches has no strong theological basis, but neither is it simply a technical skirmish.
As the World Council of Churches has noted, much of Orthodox Christianity is located in the Middle East, where it has frequently been the minority religion, and in Eastern Europe, where until recently it faced hostility from communist governments.
But in 2014, the two celebrations occurred on the same date, April 20.