Why the Easter holiday is so late this year

Over the centuries, people around the world have found lots of things to squabble about — including “the celebration of God’s holy and supremely excellent day.”That description of Easter was written by Epiphanius of Salamis not long after the First Council of Nicaea met in 325. There and then, it was decided that all Christian churches would celebrate Easter on the same day (whatever that day is); and that the complicated Hebrew calendar would no longer be factored in. Easter, and its associated holy days — Ash Wednesday, Palm Sunday, Maundy Thursday and Good Friday — are called “moveable feasts,” because the dates on which they fall are determined by the cycles of the sun and moon. The formula established by the Church of Alexandria was for Easter to fall on the first Sunday after the full moon following the northern hemisphere’s vernal equinox.It sounds pretty simple, and after many centuries it evolved as the standard for Western Christians. So how is it, then, that Easter can fall on any Sunday from March 22 to April 25?That spread of time is especially noticeable this year, because Easter falls on April 24. The last time Easter fell on the latest possible date was 1943, and it won’t happen again until 2038.A mere three years ago, Easter came very early, on March 23 (that will happen again in 2160). The last time Easter fell on March 22 was in 1818; it won’t do so again until 2285.Equinox always March 21How does such an apparently simple equation allow for such disparities in dates? And how are the dates selected?The church does not use the vernal equinox of March 20, which is the date it appears on the civil calendar. Never mind that the equinox (when day and night are exactly the same length) is an astronomical occurrence that can fall on March 19 or 21, as well. The fixed ecclesiastical date is March 21, which establishes the starting point for the math that follows. As decreed by the church, the full moon in question is the Paschal full moon. (“Paschal” is a word derived from “Passover.”)According to Wikipedia, this is a brief description of how the Paschal moon is determined:“Nineteen civil calendar years are divided into 235 lunar months of 30 and 29 days each [the so-called ‘ecclesiastical moon.’] The period of 19 years [the metonic cycle] is used because it produces a set of civil calendar dates for the ecclesiastical moons that repeats every 19 years while still providing a reasonable approximation to the astronomical facts. “The first day of each of these lunar months is the ecclesiastical new moon. Exactly one ecclesiastical new moon in each year falls on a date between March 8 and April 5 inclusive.“This begins the paschal lunar month for that year, and 13 days later is the paschal full moon. Easter is the Sunday following the paschal full moon. In other words, Easter falls from one to seven days after the paschal full moon, so that if the paschal full moon is on Sunday, Easter is the following Sunday.”And if that isn’t sufficiently complex, also factoring in are years with an embolismic month (known as a leap year to us laypersons).Of course, this is all related to the Gregorian calendar. Eastern Orthodox and Oriental Orthodox churches use the Julian calendar, and celebrate Easter between April 4 and May 8.Passover and EasterThe connection between Easter and Passover, a commemoration of the escape of the ancient Israelites from Egypt, is symbolic and remains calendar-related to a degree, as both fall in early spring. Both celebrate new life. The two names are often translated into versions of each other in various languages. The original Easter date was the first Sunday after Passover. On the night before his crucifixion, Jesus, who was, of course, Jewish, celebrated Passover with his disciples, during what Christians now call the Last Supper.