This dating of Easter is based on the lunar calendar that
Hebrew people used to identify Passover, which is why it moves
around on our Roman calendar.
Found out a couple of things you might be interested in.
Based on the above, Easter can actually be one day earlier
(March 22) but that is pretty rare.
This year is the earliest Easter any of us will ever see the
rest of our lives! And only the most elderly of our population
have ever seen it this early (95 years old or above!). And none
of us have ever, or will ever, see it a day earlier!
Here are the facts:
The next time Easter will be this early (March 23) will be the
year 2228 (220 years from now). The last time it was this
early was 1913 (so if you’re 95 or older, you are the only
ones who were around for that!).
The next time it will be a day earlier, March 22, will be in
the year 2285 (277 years from now). The last time it was on
March 22 was 1818. So no one alive today has, or ever will see
Easter any earlier than this year!
If you need to know how the date for Easter is determined,
click here: http://www.assa.org.au/edm.html#Calculator