Easter, also known as Resurrection Sunday, celebrates the resurrection of Jesus Christ. Christians believe that Jesus was crucified on Good Friday, and rose from the dead after three days on Easter Sunday. Easter Sunday marks the end of Lent, a 40-day period of fasting, prayer and penance, and is followed by a 50-day period called Eastertide, which ends with Pentecost Sunday.
The celebration of the resurrection of Jesus is observed as an Easter Vigil (also known as Paschal Vigil) in Roman Catholic, Eastern Orthodox, Lutheran and some Anglican churches, and “Sunrise Service” in many Protestant churches. Borrowing from the Jewish tradition, a liturgical day begins at sunset, and thus the Easter Vigil begins between sunset on Holy Saturday and sunrise on Easter Sunday. The Easter Vigil service moves from darkness to light, symbolically re-enacting the Easter story of Jesus rising from the dead. The service begins outside the church where the priest lights and blesses a fire. A Paschal candle, representing the Risen Christ, is lit from that fire. The candle is processed through the church, and the Exsultet, Easter proclamation, is sung. Passages from the Bible are read, the Gloria and Alleluia are sung, and the Eucharist (or Holy Communion) is celebrated. In many churches, this is also a time when new members are baptized into the Church in accordance with ancient tradition. The “Sunrise Service” is similar, but held outside early in the morning on Easter Sunday, so that attendants can see the sun rise.
- Easter is a “movable feast”, which means that its date is not fixed in the calendar.
- The date is calculated according to the Lunar Calendar.
- Easter is related to the Jewish festival of Pesach (Passover).
- In Christian Religion the Easter is celebrated on the first Sunday following the first Spring Full Moon.
- Even though Spring Equinox can astronomically fall on different day each year, to simplify the calculation of Easter, the Spring is officialy set to begin on March 21st.
- If the first Spring Full Moon falls on Sunday, then the Easter will fall on the following Sunday.
Calculating the Date of Easter Sunday
Easter Day is always the Sunday after the full moon that occurs on or after the spring equinox on March 21, a date which is fixed in accordance with an ancient ecclesiastical computation, and which does not always correspond to the astronomical equinox. This full moon may happen on any date between March 21 and April 18 inclusive. If the full moon falls on a Sunday, Easter Day is the Sunday following. But Easter Day cannot be earlier than March 22 or later than April 25.
The simplest way to explain the date of Easter is that it falls on the first Sunday after the full moon that follows 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 just on or after March 21 is known as the Paschal full moon. Paschal derives from “pascha,” the Greek and Latin word for “passover.” The Gregorian calendar, instituted by Pope Gregory XIII, went into effect in 1582. 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.
Calculate the Date of Easter Sunday
To find the date of Easter Day in any particular year, it is necessary to have two points of reference – the Golden Number and the Sunday Letter for that year.
1. The Golden Number (Prime) indicates the date of the full moon on or after the spring equinox of March 21, according to a nineteen-year cycle. These Numbers are prefixed in the Calendar to the days of the month from March 22 to April 19 inclusive. The Moon repeats the dates of its phases approximately every 19 years (the Metonic cycle), and the Golden Number represents a year in that cycle.
To Find the Golden Number
The Golden Number of any year is calculated as follows: Take the number of the year, add 1, and then divide the sum by 19. The remainder, if any, is the Golden Number. If nothing remains, then 19 is the Golden Number.
Example: The current year of our Lord is 2025
2025 + 1 = 2026
2026 / 19 = 106.63
106 x 19 = 2014
2026 – 2014 = 12 (Golden Number)
2. The Sunday Letter identifies the days of the year when Sundays occur. After every date in the Calendar a letter appears – from A to g. Thus, if January 1 is a Sunday, the Sunday Letter for the Year is A, and every date in the Calendar marked by A is a Sunday. If January 2 is a Sunday, then every date marked with b is a Sunday, and so on through the seven letters.
To Find the Sunday Letter
The Sunday (Dominical) letter is found by finding the next preceding 100th year which currently is 2000. The remainder is 25 (Remainder of the current year). 25 intersects with the “Hundreds of Years” table and the “Years in excess of Hundreds of Years” table at “e”. Therefore the Sunday letter is “e”. (Indicated by the blue highlight below)
In leap years (bissextile years), however, the Sunday Letter changes on the first day of March. In such years, when “A” is the Sunday Letter, this applies only to Sundays in January and February, and “g” is the Sunday Letter for the rest of the year. Or if “d” is the Sunday Letter, then “c” is the Sunday Letter on and after March 1.
Note: All Bissextile or leap years, the Letter under the number marked with an asterisk is the Sunday letter for the months of January and February; and the letter under the Number not so marked is the Sunday letter for the remainder of the year.
Example: In the year of our Lord 2024 the Sunday Letter is “f” due to a leap year
[1928 Book of Common Prayer – Oxford Press: ISBN: 9780195285062]
[1928 Book of Common Prayer – Oxford Press: ISBN: 9780195285062]
Example: for the year of our Lord 2025, the golden number is 12 and the Sunday letter is “e”. Now we check the calendar and find Easter Sunday.
The Golden Number is the numerical number to the left of the date in the calendar. Our golden number for the year 2025 is “12”, we need to check April.
The golden number “12” lands on April 13th, which is the first full moon after the Spring Equinox. Because our Sunday letter is “e”, we go to the following Sunday where “e” appears, which is April 20th. Easter Sunday falls on April 20th in the year of our Lord 2025.
Final Notes:
The Spring or Vernal Equinox is the day in which the length of day and night are the same. Moving forward, past the Spring equinox, there is more daylight during the day, hence, Christ shines his light over the world.
There are 19 golden numbers and Easter must fall between Mar 21st and Apr 18th of every year.
Where did this calculation come from? – The Council of Nicea in 325 AD, The First Council of Nicaea, held in Nicea in Bithynia (in present-day Turkey), convoked by the Roman Emperor Constantine I in 325, was the first ecumenical conference of bishops of the Christian Church, and most significantly resulted in the first uniform Christian doctrine. With the creation of the Nicene Creed, a precedent was established for subsequent ‘general ( ecumenical) councils of Bishops’ (Synods) to create statements of belief and canons of doctrinal orthodoxy— the intent being to define unity of beliefs for the whole of Christendom — a momentous event in the history of the Church and subsequent history of Europe.
For the propeller heads: A pure math solution for Easter Sunday calculation
Links:
1928 Book of Common Prayer
http://justus.anglican.org/resources/bcp/1928/BCP_1928.htm
Spring Equinox information
https://www.timeanddate.com/calendar/spring-equinox.html
Easter Sunday Calculator
https://www.giangrandi.org/soft/easter/easter.shtml
Astronomical Dates
https://promenade.imcce.fr/en/pages4/440.html
