But why is the paschal full moon used to determine the date of Easter? Passover fell on the date of the paschal full moon in the Jewish calendar, and the Last Supper (Holy Thursday) occurred on the Passover.
Therefore, the very first Easter Sunday—the day on which Christ rose from the dead—was the Sunday after Passover.
Therefore, for the Orthodox, the Sunday following the paschal full moon has to fall after April 3 on the Gregorian calendar.
This has the effect, in most years, of pushing the date of Orthodox Easter later than the date of Western Easter on the Gregorian calendar.
Many Christians believe that the date of Easter is determined by the date of Passover, and so they are surprised when, in years such as 2008, Western Christians celebrate Easter before the Jewish celebration of Passover.Easter is a moveable feast, which means that it does not occur on the same date every year. Easter can occur as early as March 22 and as late as April 25, depending on when the paschal full moon occurs. In practice, that means that Easter is always the first Sunday after the first full moon that falls on or after March 21.And why Eastern Orthodox churches usually celebrate Easter on a different day than Western churches?These are good questions with answers that require a bit of explanation.Therefore, many people assume that the Eastern Orthodox calculate the date of Easter differently and that the Orthodox Church includes in its calculation a consideration of the modern date of Passover.