The Eastern Cross/Guides/Byzantine time
The clock of the Holy Mountain
Byzantine time
On Mount Athos the day begins at sunset, and the clocks say so. This is the time where you are, kept the monastery way.
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I · Today
The day, from sunset to sunset
The Byzantine day starts in the evening. Night comes first, then morning, the order of Genesis: "the evening and the morning were the first day." Here is today where you are, with the hours of prayer the Church has kept since the early monks.
| Service | Your time | Byzantine |
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Times follow the sun the way the old hours of prayer do. They show when each service traditionally falls. Your parish or monastery keeps its own schedule.
II · Convert
Change any time to Byzantine time, or back
Reading a monastery schedule, or planning a call with someone on the Holy Mountain? Pick a day and a time.
In Byzantine time a day's night comes first, so its first hours fall on the evening before.
III · How it works
How the monks keep time
Sunset is hour zero. Byzantine time counts the hours of the day from sunset. On the 12-hour clock faces used on Athos, that moment reads 12 o'clock. The hands then run through the twelve hours of the night, and around again through the twelve hours of the day.
The clock moves with the seasons. Sunset comes earlier in winter and later in summer, so the gap between Byzantine time and ordinary time keeps changing. On Athos at midwinter the Byzantine clock already reads nearly 7 when ordinary clocks strike midnight. At midsummer it reads about 3.
Clocks are set by hand. The monasteries use tables printed every year in the church calendar to convert between Byzantine time and Greek time. In most monasteries the clocks are set on Saturday night so that they read 12 at sunset, and that setting holds for the week. The button above marked Set weekly, as on Athos keeps the clock that way. Exact to today uses each day's own sunset.
It is the Church's own day. The liturgical day begins at Vespers, which is why a feast starts the evening before, with the vigil. On Athos the clock simply agrees with the services. When it turns 12 at sunset, the next day's saints are already being sung.
If you keep the hours of prayer at home, our guide to Orthodox prayer has morning and evening prayers you can pray along with, and the Orthodox calendar shows whose feast begins tonight.
IV · Questions
Questions
Why does a Byzantine clock need my location?
Because sunset depends on where you are and moves a little every day. This page asks once, remembers the place on your own device, and works the sunset out for you every time you open it. You don't need to enter coordinates again.
Does every monastery on Athos use Byzantine time?
Most do, but not all. A few keep ordinary Greek time, and the details can differ between houses. If you're visiting, ask the guest master which clock the monastery keeps. It matters when the gate closes at sunset.
Is this the same as the time on Mount Athos?
Only if you choose Mount Athos as your place. Byzantine time is local: it runs from your own sunset. The small card under the clock shows the time on the Holy Mountain right now, worked out from sunset at Karyes.
Why are the hours of prayer not exactly 3 hours apart?
The ancient hours of prayer divide the daylight into twelve equal parts, so in summer each hour is longer and in winter shorter. The First Hour is at sunrise, the Sixth at midday, and the Ninth three of those hours before sunset. The clock itself uses ordinary hours of 60 minutes.
What happens near the North Pole?
Where the sun doesn't set or doesn't rise, there is no sunset to count from, and the page tells you so. Monasteries in the far north keep ordinary time for that reason.
Is it the same as Ottoman time?
They're close cousins. Ottoman clocks were also set to 12 at sunset. Byzantine time is older and is the one the Orthodox monasteries kept, and still keep.
V · Sources
Sources
On Byzantine time
- Byzantine timeWikipedia. The day begins at sunset; kept on Mount Athos and at Mar Saba.
- Monastic Life and Byzantine HourHoly Monastery of Pantokrator, Mount Athos. Sunset reads 12; clocks are set on Saturday night for the week.
- Byzantine time system of the Serbian monastery Hilandar and the whole of Mount AthosFaculty of Geography, University of Belgrade. How the yearly tables in the church calendar are worked out.
How the sunset is worked out
- NOAA solar calculator equationsSunrise and sunset are calculated on your device, accurate to about a minute away from the poles.
Keep the hours with people who keep them
The Eastern Cross is an Orthodox Christian community on Discord, with a daily bulletin of feasts, saints and fasts, and people who pray.
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