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Easter Calculation Rule:
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Easter is calculated as the first Sunday after the first full moon occurring on or after March 21 (the ecclesiastical vernal equinox). This calculation follows the Gregorian calendar rules established in 1583.
The calculator uses Gauss's algorithm for calculating the date of Easter:
1. Calculate the "golden number" (a = year mod 19)
2. Calculate century (b = floor(year / 100))
3. Calculate corrections for moon's orbit (d, e, f, g)
4. Find the "epact" (h = (19a + b - d - g + 15) mod 30)
5. Find the full moon (month and day calculations)
6. Find the following Sunday
Explanation: The algorithm accounts for the complex relationship between the solar year, lunar month, and weekly cycle to determine the correct date.
Details: Easter is the most important feast in the Christian calendar, and its date determines many other religious observances. Accurate calculation is essential for liturgical planning.
Tips: Simply enter any year between 1583 (when the Gregorian calendar was introduced) and 9999. The calculator will display the date of Easter Sunday for that year.
Q1: Why does Easter's date change every year?
A: Easter is based on a lunisolar calendar (combining moon phases and solar year) rather than a purely solar calendar like our civil calendar.
Q2: What's the earliest possible date for Easter?
A: March 22 (last occurred in 1818, will next occur in 2285)
Q3: What's the latest possible date for Easter?
A: April 25 (last occurred in 1943, will next occur in 2038)
Q4: Do all Christians celebrate Easter on the same date?
A: No, Eastern Orthodox churches often celebrate on a different date due to using the Julian calendar for calculation.
Q5: Why was March 21 chosen as the vernal equinox date?
A: This was the approximate date of the equinox in 325 AD when the calculation rules were established at the First Council of Nicaea.