Happy Easter

Why does the date of Easter change each year? Because almost 1700 years ago an ecclesiastical council determined that Easter should be celebrated on the Sunday after the first full moon on or after the day of the vernal equinox.

Did you get that? :)

Wikipedia adds some math and probability to the situation:

Accordingly, Gregorian Easter can fall on 35 possible dates - between March 22 and April 25 inclusive.^[48] It last fell on March 22 in 1818, and will not do so again until 2285. It fell on March 23 in 2008, but will not do so again until 2160. Easter last fell on the latest possible date, April 25, in 1943 and will next fall on that date in 2038. However, it will fall on April 24, just one day before this latest possible date, in 2011. The cycle of Easter dates repeats after exactly 5,700,000 years, with April 19 being the most common date, happening 220,400 times or 3.9%, compared to the median for all dates of 189,525 times or 3.3%.

I'd like to see the numbers for this, but not so badly that I'll try to generate them myself. Every 5.7 million years? That interests me.