Early Christians devised a complicated technique to keep Easter in sync with the lunar calendar.
It is based on a calculation that considers both the Spring Equinox and the moon’s phases.
The Spring Equinox, which occurs on March 20 in the northern hemisphere, is the day when the length of day and night are equal.
The Nicaean Council in 325 AD established the method for calculating the date of Easter.
Easter will be observed on the first Sunday following the first full moon that occurs on or after the Spring Equinox, the council resolved. Easter can therefore occur on any Sunday between March 22 and April 25.
Most nations in the world use a calendar system called the Gregorian calendar.
The Julian calendar, which is older and less precise than the Gregorian calendar, is used by certain Christians in Greece, Cyprus, and Romania.
This indicates that they observe Easter a different day than most Christians. Easter celebrations will begin on April 14 rather than Good Friday, as the majority would do.
