How the Calendar is created
Advent always has four Sundays, but it can be either three or four weeks long. When Advent 4 is on Dec 24th, the morning is Advent 4 and the afternoon is Christmas Eve.
Advent Sundays are calculated finding the 4 Sundays before December 25th, even if one of those Sundays is Christmas Eve. There can be up to two Sundays after Christmas, but most years there is only one.
Epiphany (6 Jan) is 12 days after Christmas (25 Dec). This is the twelve days of Christmas. The Sunday nearest to January 6th can be celebrated as Epiphany Sunday, if the nearest Sunday is after Epiphany it can be either "Epiphany Sunday" or "The Baptism of the Lord" based on local preference.
Epiphany Sundays are then counted until the Sunday before Ash Wednesday. The readings labelled the "Last Sunday of Epiphany", are always last. So, if you have five weeks of Epiphany, instead of celebrating the fifth week, you celebrate the "Last Sunday of Epiphany". A good way to remember is that the Last Sunday of Epiphany has the Ash Wednesday readings.
Lent always has 46 days, 40 not counting the Sundays (which are a feast day in Lent). Lent is always calculated back from Easter. Lent, like Advent and the Easter Season, has a fixed number of Sundays; the other seasons expand and contract to fit them.
In 325AD the Council of Nicaea established that Easter would be held on the first Sunday after the first full moon occurring on or after the spring equinox. From that point forward, the Easter date has depended on the ecclesiastical approximation of March 21st for the equinox. Easter is delayed by one week if the full moon is on Sunday. Easter can be as early March 21st (the year 1818) or late as May 10th (the year 2268).
Easter determines these dates
- Ash Wednesday (47 days before Easter)
- Ascension Day (10 days before Whit Sunday)
- Palm Sunday (1 week before Easter Sunday)
- Pentecost (Whit Sunday) (7 weeks after Easter Sunday)
The Easter Season always has seven Sundays, plus Pentecost.
Day of Pentecost :
Pentecost Sunday ends the fiftieth day after Easter (the Greek word for "50th" is “Pentecost” ). It does not begin a “Pentecost Season”. The earliest possible date is May 10th in 1818 and 2286, (Proper 1), and the latest possible date is June 13th, 1943 and 2038 (Proper 6).
Trinity Sunday :
The first Sunday after Pentecost. The Earliest possible date is 17th May, 1818 and 2286, (Proper 2) and the latest date is 20th June, (Proper 7) 1943 and 2038. Ordinary Time: (aka Kingdomtide)
Ordinary Time :
Ordinary time, does not mean common. It refers to Ordinal time, or Ordinal numbers, which means First, Second, Third etc, which are ranks, versus Cardinal numbers which are 1,2,3,.. which means how many. Ordinary weeks are set backward from the last week of the Church Year, which is always Proper 29.
When do the Proper’s start? It has been determined that earliest possible Day of Pentecost is May 10th, hence Proper 1 is the closest to May 11th.
The Propers are planned backward. The Sunday before Advent 1 (of the next year) is Proper 29, then the Propers fill in before that until they hit Pentecost and the Proper closet to that Sunday after Pentecost is used. The early Propers are rarely used, but those readings still find their way into the lectionary, because they are repeats of the last weeks of Epiphany. You may notice the readings for Proper 1 are the same as the readings for the 6th Sunday after Epiphany; Proper 2 is the same as seventh Sunday after Epiphany. This continues to the 8th Sunday after Epiphany, the greatest number of Sundays possible after Epiphany.
- Sixth Sunday After Epiphany = Proper 1
- Seventh Sunday After Epiphany = Proper 2
- Eighth Sunday After Epiphany = Proper 3