Greek Calendar
In the Greek world every city-state measured time by its own lunar calendar. This tool brings together the twelve Athenian months, their festivals, Hesiod's star calendar and the cycles of the Antikythera Mechanism. The twelve zodiacal signs and the natal chart also took shape in this world, in Hellenistic Alexandria.
Why This Reconstruction?
In the Hellenistic period Alexandria brought together the largest library the world then knew, its most capable mathematicians, and the priests who read the sky most systematically. The centuries of Babylonian lunar and planetary records, the thirty-six Egyptian decans with their fixed-star maps, and the Greek gift for geometric abstraction all met in that one city. The natal chart (genethliology), the twelve-house system, the doctrine of aspects and the sign-planet-deity correspondences that spread across the Mediterranean came out of this synthesis. The legend of Hermes Trismegistus was born at the same junction. The Greek Hermes merges here with the Egyptian Thoth.
Greece itself, however, had no single calendar. Every polis used its own month names, its own festival year and its own rule for adding months. Athens and Sparta share almost no month names at all. The Macedonian calendar runs on a logic entirely different from the Athenian one. Even so, the games held every four years at Olympia and Delphi and every two years at Nemea and the Corinthian Isthmus tied the whole Hellenic world to one shared rhythm. The Greeks counted time by this four-year cycle, which they called the Olympiad.
This tool rebuilds that system through the lens of today. The first new crescent after the summer solstice of the chosen year is calculated as Hekatombaion 1 of the Athenian calendar, and the twelve months follow in order. For each month the tool displays the Athenian festivals, the month-specific deities, the matching star entries from Hesiod's agricultural calendar of heliacal risings, and the three-decade lunar-phase naming system for the days. The Panhellenic Games cycle, the front and back dials of the Antikythera Mechanism, the birth-line of Hellenistic astrology, and the month names of other poleis appear in separate sections.
Many Greek words that have passed into modern English began as astronomical terms: zodiac, planet, cosmos, astronomy, parapegma, heliacal. Classical astrology is a Greek, Egyptian and Babylonian synthesis, and it left its mark on English through words like these.
The Twelve Months
The Athenian calendar is the best documented of all the Hellenic polis calendars. Each month begins on the evening when the first new crescent appears on the western horizon after the summer solstice. Click a month to see its festivals, lunar-deity associations, Hesiod's star records, and the three-decade naming of the days.
Hesiod's Stellar Calendar
Around 700 BCE in Boeotia, Hesiod set out the year of the Greek farmer in Ἔργα καὶ Ἡμέραι, Works and Days. This calendar marks the year by the stars rather than by month names. The heliacal risings and settings of the Pleiades, Arcturus, Sirius and Orion tell the farmer when each task is due.
Panhellenic Games
This four-year cycle is called the Olympiad. The whole Hellenic world dated its events by it. A geared dial on the back of the Antikythera Mechanism tracks the same cycle.
The Antikythera Mechanism
Dated to roughly 150-100 BCE, this device is the earliest known analog astronomical computer. Greek sponge divers found the wreck of a Roman ship in 1900 and the mechanism was raised from the sea in 1901. Its bronze gears tracked the positions of the Sun, the Moon and the five planets, along with lunar phases, eclipses, the Metonic cycle, the Olympic cycle and the heliacal risings of stars recorded in its parapegma.
Front Dial · Solar-Zodiacal
- Outer ring Egyptian calendar, 12 months × 30 days + 5 epagomenai
- Inner ring Greek zodiac, 12 × 30°
- Pointers Sun, Moon, and five planetary positions
- Lunar sphere phase indicator (black-and-white)
- Parapegma heliacal risings of stars inscribed
Back Dial · Lunisolar Cycles
- Metonic spiral 19 years = 235 synodic months
- Callippic 76 years = 4 Metonic cycles
- Olympiad 4 years, Panhellenic Games
- Saros spiral 18-year eclipse cycle
- Exeligmos 54 years, triple Saros
The Birth of Hellenistic Astrology
After Alexander conquered Egypt in 332 BCE, the Babylonian, Egyptian and Greek traditions came together in Alexandria. The technique of the natal chart emerged along that line.
Other Polis Calendars
The table below compares the months of other city-states with the Athenian calendar. Each city-state used its own month names and the names rarely overlap. Moving from one calendar to another is usually an indirect business.
| # | Athens | Sparta | Macedonia | Delphi | Approximate Season |
|---|---|---|---|---|---|
| 1 | Hekatombaion | Hekatombeus | Loios | Apellaios | Jul-Aug |
| 2 | Metageitnion | Karneios | Gorpiaios | Boukatios | Aug-Sep |
| 3 | Boedromion | (unknown) | Hyperberetaios | Boathoos | Sep-Oct |
| 4 | Pyanepsion | (unknown) | Dios | Heraios | Oct-Nov |
| 5 | Maimakterion | (unknown) | Apellaios | Daidaphorios | Nov-Dec |
| 6 | Poseideon | (unknown) | Audnaios | Poitropios | Dec-Jan |
| 7 | Gamelion | (unknown) | Peritios | Amalios | Jan-Feb |
| 8 | Anthesterion | (unknown) | Dystros | Bysios | Feb-Mar |
| 9 | Elaphebolion | Hyakinthios | Xandikos | Theoxenios | Mar-Apr |
| 10 | Mounichion | (unknown) | Artemisios | Endyspoitropios | Apr-May |
| 11 | Thargelion | (unknown) | Daisios | Herakleios | May-Jun |
| 12 | Skirophorion | (unknown) | Panemos | Ilaios | Jun-Jul |
Most Spartan month names are lost or disputed. The ones we know come from the city's two principal festivals. Alexander carried the Macedonian names into the Near East during the Hellenistic period, and they stayed on as the official calendar of the Seleucid Empire.
Primary and Secondary Sources
- Hesiod, Ἔργα καὶ Ἡμέραι (Works and Days), ca. 700 BCE; trans. M. L. West, Oxford UP, 1988.
- Athenian calendar; J. D. Mikalson, The Sacred and Civil Calendar of the Athenian Year, Princeton UP, 1975.
- Athenian festivals; H. W. Parke, Festivals of the Athenians, Cornell UP, 1977.
- Panhellenic Games; D. G. Kyle, Sport and Spectacle in the Ancient World, Wiley-Blackwell, 2014.
- Antikythera Mechanism; T. Freeth and A. Jones, "The Cosmos in the Antikythera Mechanism," ISAW Papers 4, 2012.
- Antikythera front dial; Y. Bitsakis and A. Jones, The Front Dial and Parapegma Inscriptions, Almagest 7, 2016.
- Hellenistic astrology; C. Brennan, Hellenistic Astrology: The Study of Fate and Fortune, Amor Fati, 2017.
- Greek astronomy; J. Evans, The History and Practice of Ancient Astronomy, Oxford UP, 1998.
- Eleusinian Mysteries; W. Burkert, Ancient Mystery Cults, Harvard UP, 1987.
- Anthesteria; R. Hamilton, Choes and Anthesteria, Michigan UP, 1992.
- Ptolemy, Tetrabiblos, 2nd c. CE; trans. F. E. Robbins, Loeb Classical Library, 1940.
- Dorotheus of Sidon, Carmen Astrologicum, 1st c. CE; trans. D. Pingree, Teubner, 1976.
- Vettius Valens, Anthologiae, 2nd c. CE; trans. M. Riley (pdf), 2010.
- Lunisolar cycles and the Olympiad; C. Tuplin and T. Rihll (eds.), Science and Mathematics in Ancient Greek Culture, Oxford UP, 2002.