Why does easter switch months

Since the days of early church history, determining the precise date of Easter has been a matter for continued argument. For one, the followers of Christ neglected to record the exact date of Jesus' resurrection. From that point on the matter only grew increasingly more complex. At the heart of the matter lies a simple explanation. Easter is a movable feast.

The earliest believers in the church of Asia Minor wished to keep the observance of Easter correlated to the Jewish Passover. The death, burial, and resurrection of Jesus Christ happened after the Passover, so followers wanted Easter always to be celebrated after the Passover. And, since the Jewish holiday calendar is based on solar and lunar cycles, each feast day is movable, with dates shifting from year to year.

Prior to A. At the Council of Nicaea in A. The date of the Paschal Full Moon is determined from historical tables. The date of Easter no longer directly corresponds to lunar events. As astronomers were able to approximate the dates of all full moons in future years, the Western Church used these calculations to establish a table of Ecclesiastical Full Moon dates.

Together, the mystery of the Last Supper, the sacrifice of Good Friday, and the resurrection of Easter form the new Passsover— the new Pasch. However, according to St.

Bede d. This is because in the Bible, the death, burial, and resurrection of Jesus Christ happened after the Jewish festival of Passover , and followers wanted it to be celebrated as such. However, this is slightly tricky because the Jewish calendar is based on lunar cycles, whereas Christian culture is based on the sun. A solar year is just over days and a lunar year is about days , so collaborating the two can be complicated.

Passover also changes every year, because it's calculated by the first full moon following something called the vernal equinox — a day in spring when night and day are exactly the same length. An article on ThoughtCo says that in the early days of the Christian Church, Easter would fall on the first Sunday immediately after the vernal equinox. However, to establish a more standardised system, in a table was recorded by astronomers to determine all the future Ecclesiastical full moons.

These land on the 14th day of the lunar month. Ever since , the Passover full moon — or Paschal full moon — has been determined from these historical tables, and is the first full moon date after March Easter then falls on the Sunday immediately following it.

Or at least, it's supposed to. A fixed date has been proposed many times over the years, even as recently as five years ago, but has always been rejected. Engler says keeping with tradition of what is called the "movable feast," which does not fall on a fixed date in the Gregorian or Julian calendars, was too important.

About years ago, Engler says the Western Christians decided to revise the Julian calendar — which meant having three fewer leap years every four centuries. Because of that slight alteration, the two calendars are slowly diverging and the Julian calendar drifts forward. Another aspect of the floating date of Easter has to do with the mismatch between the periodicity of the sun and the moon and the long history of humans looking to create a consistent calendar. Many of the early calendars created by humans were based on the lunar cycle, which are still used today by religious Muslims and Jews.

The Jewish calendar is actually a "lunisolar" calendar, which has months based on the cycles of the moon but corrects with a leap month roughly every three years, which keeps it more or less aligned with the solar calendar and in sync with the seasons. Julius Caesar instituted the Julian calendar in 46 A. But a problem arose because over centuries the vernal, or spring, equinox wandered. It modified leap years to fine-tune the actual solar periodicity, and it's the calendar used today in North America.

Eastern churches use the Julian calendar still, while Western churches use the Gregorian calendar today.