That magic lunisolar number

Inquiring minds want to know: Why is Easter not on a fixed calendar date? The original movable feast is Easter, based on which the dates of all other movable feast days such as the entire Lenten season, Ascension and Pentecost are determined So how is the date of Easter derived? There are a few ways One option is for you to acquire a Patek Philippe Calibre 89, the first watch with an indication of the date of Easter.

You can easily determine the date of Easter from year to year, using the method outlined above Determining the date of Easter in advance takes a bit more than that Determining Easter in any particular year merely requires the knowledge of the full 19-year sequence of Paschal Full Moon dates and looking at the calendar for the relevant year. Source