Syzdekistan

Those of you who got to celebrate a “white Easter” this year surely noticed that Easter was early this year. Even here in Syzdekistan, the traditional Easter dinner held outside was unusually pleasant and not on the warm side as it often is. Yes, Easter falling on March 23 is very unusual and this the earliest it will fall for the rest of our lifetimes. The next time Easter will fall on March 23 will be in the year 2160 and the last time was in 1913. The absolute earliest Easter can fall is March 22 but this is very rare and last occurred in 1818 and will next occur in 2285.

How is the date of Easter calculated? If you would have asked me this in parochial grade school I would have answered “Easter is the first full Sunday after the first full moon after my birthday which is March 21st.” Actually, it is the vernal equinox, not my birthday. However, it is actually a little more complicated than that. First of all, the Church assumes that the vernal equinox is March 21st which is a simplification. Secondly, the church uses “ecclesiastical” full moons rather than astronomical full moons. There are addition complexities due to the problems of reconciling a lunar calendar and the solar calendar. Furthermore, Eastern churches use the Julian calendar rather then our Gregorian calendar so their Easter will fall on April 27 this year.

In addition, the cycle of dates that Easter falls on repeats after exactly 5,700,000 years and if you count all of the days that Easter falls on, the most common date is April 19 which happens 3.9% or 220,400 times. You can see that really early or really late dates are quite uncommon during the cycle:

An interesting newspaper article in which the US Naval Observatory which standardizes time in the US says “It wasn’t us” when people complain about the early Easter this year can be found here. The Wikipedia has a detailed article about computing the date of Easter here.