The Orthodox church year is a double structure. One cycle is fixed to calendar dates and turns once a year; the other is movable and pivots on the date of Pascha, which itself moves. Laid over both, in the Holy Land as in several other Orthodox traditions, is a reckoning of time that still follows the older Julian calendar. Understanding these mechanics explains much about how observance at the ancient shrines is organised.
Two calendars, thirteen days
The Julian calendar, instituted in 46 BC, assumes a year of exactly 365.25 days. That figure is about eleven minutes longer than the true tropical year, an error accumulating to roughly one day every 128 years. By the sixteenth century the drift had reached ten days, and the Gregorian reform of 1582 removed them and refined the leap-year rule. Many Orthodox churches, including the church of Jerusalem, retained the older reckoning for the fixed cycle, and the gap now stands at thirteen days, where it will remain until 2100.
In practice a feast kept on 25 December in the older reckoning falls on 7 January of the civil calendar. A revised calendar, agreeing with civil dates for fixed feasts while retaining the traditional computation of Pascha, was adopted by some Orthodox churches from 1923; others, among them the Holy Land tradition, did not. The difference concerns the reckoning of dates alone, not the content or rank of any feast.
The computation of Pascha
Pascha is calculated by the Alexandrian rule inherited from late antiquity: it falls on the first Sunday after the first ecclesiastical full moon occurring on or after 21 March, with the equinox fixed at that date by convention and the moon taken from the nineteen-year Metonic cycle rather than from observation. Because the computation is carried out in Julian terms, and because the ecclesiastical lunar tables have themselves drifted by four or five days, Orthodox Pascha usually falls later than the Western date. In some years the two coincide; in others they stand one, four or five weeks apart.
The fixed cycle
The church year opens on 1 September, a date inherited from the Byzantine indiction. The fixed cycle assigns to each calendar day its own commemorations, hymns and readings, gathered in the twelve volumes of the Menaion, one for each month. Most days carry the memory of one or more saints; the greatest are preceded by a forefeast and followed by an afterfeast.
The movable cycle
The movable cycle is carried by two books. The Triodion opens ten weeks before Pascha, on the Sunday of the Publican and the Pharisee, and runs through the preparatory weeks, Great Lent and Holy Week. The Pentecostarion takes over at Pascha and continues to the Sunday of All Saints. Outside these seasons the Sundays follow the eight-week rotation of the Octoechos, in which each week takes one of the eight musical modes in turn, a system described on our page on Byzantine chant.
Great Lent and Holy Week
Great Lent begins on Clean Monday and runs forty days to the Friday before Lazarus Saturday. Lazarus Saturday and the Entry into Jerusalem follow, and then Holy Week, which the tradition counts as a distinct season. Holy Week in Jerusalem has a particularly deep history, because the fourth-century travel account of the pilgrim Egeria, available through the Internet Medieval Sourcebook, records services moving from site to site across the city. The Holy Saturday rite within this week is described on our page on the Holy Saturday ceremony.
The twelve Great Feasts
Beneath Pascha, which stands apart as the feast of feasts, the tradition counts twelve Great Feasts. Eight belong to the fixed cycle and appear below by their traditional dates; four are movable, defined by their distance from Pascha.
| Great Feast | Date or position | Cycle |
|---|---|---|
| Nativity of the Theotokos | 8 September | Fixed |
| Exaltation of the Cross | 14 September | Fixed |
| Entry of the Theotokos into the Temple | 21 November | Fixed |
| Nativity of Christ | 25 December | Fixed |
| Theophany | 6 January | Fixed |
| Meeting in the Temple | 2 February | Fixed |
| Annunciation | 25 March | Fixed |
| Entry into Jerusalem | Sunday before Pascha | Movable |
| Ascension | Fortieth day after Pascha | Movable |
| Pentecost | Fiftieth day after Pascha | Movable |
| Transfiguration | 6 August | Fixed |
| Dormition of the Theotokos | 15 August | Fixed |
The fasting seasons
Four multi-day fasts punctuate the year, and their lengths are governed by the same two cycles. Great Lent is the longest and strictest. The Apostles' Fast begins on the Monday after the Sunday of All Saints and ends on 28 June, so its length varies with the date of Pascha. The Dormition Fast occupies the first fortnight of August, and the Nativity Fast runs forty days from 15 November. To these are added most Wednesdays and Fridays and a small number of individual fast days.
The typikon and the shared observance at the shrines
The order in which all of this is actually sung is governed by a book called the Typikon. The version in general use descends from the usage of the monastery founded by Sabas in the Judean desert in 483, which gradually displaced the older cathedral rite of Jerusalem, known chiefly through Georgian and Armenian translations of its lectionaries. The houses in which it took shape are described on our page on the monasteries of the Judean desert; a short account of the founder appears in the encyclopedia entry for Sabas.
At the greatest of the shrines the calendar has a further practical dimension. Several Christian communities maintain the buildings under a long-standing arrangement in which each keeps defined areas and holds its own services at set times, and because those communities do not all reckon dates the same way, a single feast may be observed on different civil days within one building. The vocabulary used here is expanded in our glossary of terms, and the wider tradition is surveyed in the general account of Eastern Orthodoxy.