Lunar Calendar 101

Reconstructing Ancient Greek Calendars

Years

Decorative: illustrated pottery image of athletes racing

The lunisolar calendar operates in a cycle of 8 years. This is the period of time it takes for the lunar and solar cycles to realign while taking intercalations into account. The years are then grouped into Olympiads (periods of 4 years), named for the Olympic games. The first Olympiad is dated in the summer of 776 BCE when the games were first founded, thus as of July 2023, we are in the 3rd Year of the 700th Olympiad.


Every New Year the Archons would realign the festival and civic calendars with the seasons and civic life. This meant the calendar didn't always match up with the moon year after year but would change depending on the needs of the state and its officials, and there was a running joke that the gods in Athens never knew when to show up for their festivals because of it.  The Ancient Greek calendars traditionally start their New Year after an annual solar event, but they don't consistently start at the same time across city-states. Most calendars begin their year in tune with the Fall Equinox, such as in Sparta, or the Winter Solstice, as in Delos. Other calendars, like Athens, follow Delphi and begin the year just after the Summer Solstice.

Months

The months start on the Noumenia consistently across ancient Hellas (Greece). Noumenia translates literally as "new-moon" but referred to the first visible sliver of the waxing crescent rather than the astrological New Moon we're familiar with today. What we call the New Moon was known as the Dark Moon to the ancient Greeks, believed to be a time when spirits roamed, and made up the last days of the lunar month. Conversely, the Noumenia has a spirit of monthly celebration and prosperity. Because days began at sunset, the slight difference in timezones led to a drift in regional calendars between 1-2 days depending on how far apart from each other they were and what unique geographical differences may be at play.

Our English word for 'month' comes from the Greek word mene, meaning 'moon'. A lunar month lasts 29 days (a Hollow month) or 30 days (a Full month) in alternating fashion. This inconsistency means a lunar year falls about 11 days short of the solar calendar. In many Ancient Greek calendars this was resolved by adding an intercalary month. Athens would add a repeat Poseideon every other year so the festivals would still occur at the correct time in the season. Other city-states would add an additional 5 or so days to the last lunar month of the year instead. This means that over a period of two Olympiads (8 years) there will be 3 intercalary months inserted into the calendar.

Painting of the goddess Selene with billowing robes and the moon as her crown leans over a sleeping young man

A Full Month would never extend past the 30th day, so if for whatever reason the waxing crescent still wasn't visible by the naked eye, the 31st day would begin the Noumenia and restart the calendar. Alternating between Hollow and Full Months was how the Athenians kept their calendar balanced over the years. In a Hollow Month the count for the the 21st day would skip the "10th Day of Waning" and proceed directly to the "9th Day of Waning" so that there was always an accurate countdown to the last day of the lunar month. By later times, however, the backwards count was dropped and the 29th day was omitted from the count. Most contemporary reconstructed calendars favor the latter method for ease and clarity.

While the names of the months and New Year varied from polis to polis they all began their months on the Noumenia, meaning across all the city-states the months run parallel to each other, give or take 1-3 days. The months are named after associate gods or festivals that occurred during the month, though it isn't always the most important one or even one that was still celebrated by classical times. By observing them side-by-side you can see which festivals are ancient (Hekatombaion/Hekatombeus), whose cults were wide-spread (Artemis: Mounychion/Artemision/Artamitios/Artemisios), and which festivals were perhaps more relevant to some city-states than others (Athens' Elaphebolion v. Delos' Galaxion).

Months Across City-States
*New Year

July - Aug
 Aug - Sept
Sept - Oct
 Oct - Nov
 Nov - Dec
 Dec - Jan
 Jan - Feb
 Feb - March
 March - April
 April - May
 May - June
June - July

Athens

*Hekatombaion
  Metageitnion
  Boedromion
  Pyanopsion
  Maimakterion
  Poseideon
  Gamelion
  Anthesterion
  Elaphebolion
  Mounychion
  Thargelion
  Skiraphorion

Delos

  Hekatombaion
  Metageitnion
  Bouphonion
  Apatourion
  Aresion
  Posideon
*Lenaion
  Hieros
  Galaxion
  Artemision
  Thargelion
  Panemos

Delphi

*Apellaios
  Boukatios
  Boathoos
  Heraios
  Daidaphorios
  Poitropios
  Amalios
  Bysios
  Theoxenios
  Endyspoitropios
  Herakleios
  Ilaios

Rhodes

  Panamos
  Karneios
  Dalios
*Thesmophorios
  Sminthios
  Diosthyos
  Theudaisios
  Pedageitnyos
  Badromios
  Artamitios
  Agrianios
  Hyakinthios

Sparta

  Hekatombeus
  Karneios
  Panamos
*Herasios
  Apellaios
  Diosthyos
  ?
  Eleusinios
  Gerastios
  Artemisios
  Delphinios
  Phliastos

Decades

The concept of weeks wasn't integrated into the calendars until Roman times—instead, Athens divided months into three periods of 10 (and occasionally 9) days.

The first period of 1-10 days carried the title "histamenou", in this context meaning "beginning" as they corresponded to the waxing phases of the moon and were referred to as "the second (day of) beginning, the third (day of) beginning, etc." The second period of 11-20 days were counted as normal (11, 12, 13...) with the full moon typically falling somewhere between the 14-16th.

The third period went in descending order 10-1 in Athens to correspond with the waning phases of the moon leading up to the Dark Moon, and for that reason were referred to as "phthinontos" meaning "waning", thus "the 10th (day of) waning", "the 9th (day of) waning", etc. Sometimes this last decade was just called "the third" (i.e. the 22nd day of the lunar month is both the 9th day of waning and the third 9th).

Plutarch attributes this change in the calendar to Solon, "After the twentieth he did not count the days by adding them to twenty, but by subtracting them to thirty, on a descending scale, like the waning of the moon," but other poleis continued numbering as normal 21-30 in a Full Month or 21-29 in a Hollow one, as is the case in Hesiod's calendar. For the most part the descending order (sometimes called a backward count) is unique to the Athenian calendar. 

First Decade | Histamenou
"Day(s) of Beginning"

1 - 1st Histamenou | Noumenia: Sacred to Helios, Apollon, & the Household Gods 
2 - 2nd Histamenou | Agathosdaimon: Sacred to Agathosdaimon
3 - 3rd Histamenou | Harpokration: Sacred to Athena & the Kharities
4 - 4th Histamenou: Sacred to Hermes, Aphrodite, Eros, Hermaphroditos & Herakles
5 - 5th Histamenou: (Inauspicious Day) Sacred to Horkos & the Erinyes
6 - 6th Histamenou: Sacred to Artemis
7 - 7th Histamenou: Sacred to Apollon
8 - 8th Histamenou: Sacred to Poseidon & Theseus
9 - 9th Histamenou
10 - 10th Hisamenou

Second Decade

11 - 11th Day
12 - 12th Day
13 - 13th Day
14 - 14th Day
15 - 15th Day
16 - 16th Day
17 - 17th Day
18 - 18th Day
19 - 19th Day
20 - 20th Day 

Third Decade | Phthinontos
Day(s) of "Waning"

Full Month
21 - 10th Phthinontos
22 - 9th Phthinontos
23 - 8th Phthinontos
24 - 7th Phthinontos
25 - 6th Phthinontos
26 - 5th Phthinontos
27 - 4th Phthinontos
28 - 3rd Phthinontos
29 - 2nd Phthinontos
30 - Hene kai Nea

Hollow Month
21 - 9th Phthinontos
22 - 8th Phthinontos
23 - 7th Phthinontos
24 - 6th Phthinontos
25 - 5th Phthinontos
26 - 4th Phthinontos
27 - 3rd Phthinontos
28 - 2nd Phthinontos
29 - Hene kai Nea
-

Days

Oil painting depicting the goddess Selene, nude, stretched into a crescent shape backed by the moon

As ancient custom diligently aligns the calendar with the observance of the beautiful Selene (Moon), it is perhaps unsurprising that the ancient Hellenes (Greeks) began their days at sunset rather than sunrise. Even in ancient times, this created regional drift in the calendar between city-states that could result in a 1-2 or even 3-day drift even though they all began their months with the Noumenia (first sliver of the waxing crescent).

As you can guess, this made it difficult to schedule events across city-states in the ancient world when an event may be the 14th for one group and the 12th for another. Unfortunately, these regional differences still cause confusion and planning difficulties for modern devotees reconstructing these calendars today. The solution then and now is to use the sunsets in Athens as a baseline and adjust for local variation. For instance, most of the United States is around 12 hours behind Athens' local time which means the local reconstructed calendar typically falls a day or two behind.

Ok, one more time?
- RECAP -

If you want to reconstruct your own calendar unique to your area, simply follow the steps below:

Photo Credits

1. Title Photo: Moon Day
2. Footrace - Panathenaic Vase
3. Selena Kisses Endymion While He's Asleep - Albert Aublet
4. Athens: Personal Collection, Dori
5. Delos: Ancient Greek Theatre in Delos
6. Delphi: Personal Collection, Dori
7. Rhodes: Lindos Rhodes
8. Sparta: Last Remaining Section of Wall
9. Selene - Albert Aublet
10. Ionic Order

Bibliography