>>>Easter occurs on the first Sunday after the first full moon of the vernal equinox!<<<

Hi, Mary:

Yeah, that's a cool definition. It sounds so pagan.

>>>But I still don't know why.<<<

Oh that's where things get tricky. I guess the early church fathers considered the above defn rather pagan too. Instead of using the natural fluctuating date of the equinox, they introduced a rigid
arbitrary date and cosmic approximations into the mix. Here's their
technical definition:

>>>Easter Sunday is the Sunday following the Paschal Full Moon (PFM)
date for the year. In June 325 A.D. astronomers approximated
astronomical full moon dates for the Christian church, calling them
Ecclesiastical Full Moon (EFM) dates. From 326 A.D. the PFM date
has always been the EFM date after March 20 (which was the equinox
date in 325 A.D.).<<<
Source

But the Orthodox Church does it differently.

I like your definition better.

Cheers, Hester ... who's now really glad that she's pagan and doesn't
have to keep all this straight