Easter, a Christian holiday that celebrates the resurrection of Jesus Christ, occurs on a Sunday in spring every year. This makes it a movable feast because its actual date changes.
Consider that this year, Easter falls on April 5 while last year it fell on April 20.
The simplest way to explain the moving date is that Easter falls on the first Sunday after the full moon following the spring equinox.
Because the actual date of the spring equinox can differ by a day or two, the Catholic Church created a fixed date of March 21 to define it, known as the ecclesiastical equinox.
And the full moon that occurs on or just after March 21 is known as the Paschal full moon. Paschal derives from “pascha,” the Greek and Latin word for “passover.”
The Paschal full moon appears on April 1 this year. So Easter is on April 5, the first Sunday after the full moon’s appearance.
When can Easter occur?
The U.S. and most of the world use the Gregorian calendar, which can place the date of Easter anywhere between March 22 and April 25.
Past 10 Easter dates:
2015: April 5
2016: March 27
2017: April 16
2018: April 1
2019: April 21
2020: April 12
2021: April 4
2022: April 17
2023: April 9
2024: March 31
2025: April 20
Next 10 Easter dates:
2026: April 5
2027: March 28
2028: April 16
2029: April 1
2030: April 21
2031: April 13
2032: March 28
2033: April 17
2034: April 9
2035: March 25
The Gregorian calendar, instituted by Pope Gregory XIII, went into effect in 1582.
In the 1,417 years from 1583 through 3000, it’s most common for Easter to fall on April 16, with 61 instances. The least common dates are March 22 and 24, tied with nine instances apiece.
Eastern Orthodox churches use the Julian calendar, which can place the date of Easter anywhere between April 4 and May 8 when it’s converted back to the Gregorian calendar. This year, the Eastern Orthodox Church observes Easter on April 12.
How was Easter calculated before?
Calculating the date of Easter has been a complex matter for thousands of years because of the intricacies of accounting for both the solar and lunar cycles, as well as the Gregorian and Julian calendars.
As early as the year 222, Romans were using different methods to calculate the dates of Easter. Some methods relied on the 19-year Metonic cycle of the moon.
Churches still rely on earlier calculations of the moon phases as well as its set definition of the spring equinox, which can place Easter on a date different from what is astronomically accurate.
This article originally appeared on Palm Beach Post: When is Easter this year? And why does the date change every year?
Reporting by Palm Beach Post / Palm Beach Post
USA TODAY Network via Reuters Connect
