I have always wondered why Easter falls on different days each year, and naturally so does Good Friday. I know at some point I knew the reason for Easter’s date changes. However, I forgot. So, I did a little research.
Easter falls on the first Sunday following the Paschal Full Moon. This is the first full moon after the Spring Equinox. But that’s not quite the whole story. In A.D. 325 a full moon calendar was created naming March 21st as the ecclesiastical date of the equinox even though the actual date may be different.
Paschal comes from Late Latin paschalis, from pascha “Passover, Easter,” from Greek pascha “Passover,” from Aramaic (Semitic) pasha “pass over,” corresponding to Hebrew pesah, from pasah “he passed over”. Pasche was an early Middle English term for “Easter. ” (more info at https://www.etymonline.com/word/paschal)
Easter is a “movable feast” that is always held on a Sunday between March 22 and April 25.