The date for Easter is determined by a natural clock: the full moon.
What day 2023 is Easter Sunday.
Frankfurt – Christmas always falls on December 24th, but the second important festival of the Christian churches is different: Easter is on fixed days of the week from Friday to Monday, but the date can change.
But how exactly is the date set for Easter, who decides when Good Friday or Easter Sunday is celebrated?
The answer might surprise some: The clock for Easter is the moon, or more precisely: the full moon.
The full moon sets the pace – and the date for Easter
In order to ensure that Easter is celebrated on the same day worldwide, the Council of Nicaea laid down some rules in 325 AD.
The following rules apply today for setting the Easter date:
Easter takes place on a Sunday after the beginning of spring.
March 21 is set as the beginning of spring.
Easter is on the Sunday after the spring full moon - meaning the first full moon from March 21st.
If the spring full moon falls on a Sunday, Easter occurs on the following Sunday.
From these rules around the full moon it follows that Easter Sunday can fall on March 22 at the earliest, the latest possible date is April 25.
The spring full moon determines when Easter is celebrated
In 2023 there was already a full moon in the sky on March 7th.
This full moon is also called Lenzmond or Wormmoon - but does not apply to the calculation of the Easter date, as it was visible before the start of spring.
The first full moon after the beginning of spring in 2023 is the full moon on April 6th.
This means that in 2023 Easter Sunday falls on April 9th, which is right in the middle of the possible time span.
The full moon in April is traditionally called the Easter Moon or "pink moon".
In the next two years, Easter will move further up the calendar: in 2024, Easter Sunday falls on March 31 (full moon on March 25, 2024), in 2025 Easter will be celebrated on April 20 (full moon on March 13)
However, it is not only the date of Easter that depends on the moon – the moon also has physical effects on the earth.
Among other things, it influences the tides.
Research also assumes that the earth would be very different without the moon: it keeps the earth stable and thus ensures that the seasons on earth are constant and not too extreme.
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