Calculatng the calendar - great fun for millenia.
Figuring Easter and / or Passover - stimulating and controversial research for millenia.
It all depends on the moon and sun, of course.
Some may not be into Easter.
But for Pasch lovers, if you missed Sunday you have another chance. For some Orthodox, Eastern Rite Catholic, and other churches, today is Holyt [Maundy] Thursday, and Easter Sunday is coming up fast for the 12th.