To those of you who celebrate neither, happy first Sunday after the first full moon after the vernal equinox.
And just in case you were wondering how to calculate the date of Easter, just remember: First Sunday after the first full moon after the Vernal Equinox.
The First Council of Nicaea (325) established the date of Easter as the first Sunday after the full moon (the Paschal Full Moon) following the northern hemisphere’s vernal equinox. Ecclesiastically, the equinox is reckoned to be on March 21 (even though the equinox occurs, astronomically speaking, on March 20 in most years), and the “Full Moon” is not necessarily the astronomically correct date.
In Western Christianity, using the Gregorian calendar, Easter always falls on a Sunday between March 22 and April 25, inclusively.The following day, Easter Monday, is a legal holiday in many countries with predominantly Christian traditions.
Eastern Christianity bases its calculations on the Julian Calendar. Due to the 13 day difference between the calendars between 1900 and 2099, March 21 corresponds, during the 21st century, to April 3 in the Gregorian Calendar. Easter therefore varies between April 4 and May 8 on the Gregorian calendar (the Julian calendar is no longer used as the civil calendar of the countries where Eastern Christian traditions predominate).
Calculating Passover is a bit easier:
Passover begins on the 15th day of the month of Nisan, which typically falls in March or April of the Gregorian calendar. Passover is a spring festival, so the 14th day of Nisan begins on the night of a full moon after the northern vernal equinox.