Calendars that were used in Ancient Greece

Several calendars were used in the ancient Greek city of Athens. There was the annual festival calendar, which was mainly used by the people to determine what day it was. There was also the Conciliar calendar, which was used for financial transactions by the Boule and Ecclesia (Assembly), such as tribute payments, assessments, and payments of wages. The Attic festival calendar was a lunisolar calendar based on both the lunar months and specific solar events.

While other Greek cities had similar calendars, the Athenian or Attic calendar is best known due to inscriptions and a few literary sources. The Athenian calendar was closely related to the various seasons of the year when festivals were celebrated. The Athenian year started in relation to the summer solstice (June 21-22).

The Antikythera mechanism, used to predict astronomical events and calendar in ancient Greece. (Sterphotography/Dreamstime.com)

This event was used as the starting point to determine the beginning of the Athenian year, not the beginning itself. The next event was after this date was when the first new Moon of the year occurred beginning with the first sliver of the Moon appearing which now corresponded to the first day of the new year. This meant that the new year could begin up to a month after the summer solstice.

The Athenians then began their year, which contained twelve lunar months. This meant that the year would be 354 days instead of the 365 days of a solar year. To correct for this variance, the Athenians would add an extra month, an intercalated or additional inserted month every third year, producing a leap year of 384 days. This extra month was typically added as a second sixth month so that the months were five, six, six (extra), and seven. The extra month, however, could be added to other months so that months 1, 2, 6, 7, and 8 all are known to have a repeated month.

The months were known from festivals in the Athenian countryside, but most were seemingly not celebrated or commemorated. The sixth month, Poseidon, did take its name from the sea god Poseidon, but many of the great festivals, such as the Panathenaia (Dionysia), did not have months named for them. This is probably because many of the original months were already known when these later festivals were established. Many of the festivals occurred during the early part of each month.

Since the months began at various times, it is difficult to give exact modern similarities, and only broad comparisons can be made. The first month was Hek- atombaion, beginning in the summer corresponding to July/August. This was followed by Metageitnion, in August/September; and Boedromion, in September/ October, finished the season. Fall or autumn would begin with Pyanepsion, held in modern October/November; Maimakterion, in November/December; and the sixth month, Poseideon, in December/January. Winter began with the seventh month, Gamelion, corresponding to January/February, followed by Anthesterion, in February/March, and then Elaphebolion, in March/April, ended the winter. Spring began with Mounichion, in April/May, followed by Thargelion, in May/ June, and the last or twelfth month was Skirophorion, in June/July.

Each month would have either full months of thirty days or hollow months of twenty-nine days. This allowed for the fact that for two lunar months, the total number of days actually equaled 59.06 days as opposed to 60. The hollow month occurred only from the omission of days during the last third of the lunar cycle.

The actual days of the months were based on the waning and waxing of the Moon. The first day was noumenia, meaning the new Moon when the first sliver appeared. After that, the days were counted upward, with the next being the second waxing and the next third waxing up to the tenth waxing. The next day was the 11th, which went up to the 19th, with the 20th being called the “earlier tenth waning.”

The final ten days were then counted downward, with the 21st being the “later tenth waning,” then the ninth waning down to the 29th day being the second waning, and the last day was known as the “old and new” Moon. When there was only twenty-nine days (a hollow month), the second waning day was called the “old and new” Moon.

The Conciliar calendar also had ten months, which began in the midsummer, a week after the summer solstice. The months corresponded to the ten tribes and were called Erektheis, Aigeis, Pandionis, Leontis, Akamantis, Oineis, Kekropis, Hippothontis, Aiantis, and Antiokhis. Since this year only had ten months, each month lasted 35-38 days and was based on a solar year of 365 days. It was therefore close to the true solar calendar of modern times. These months, or Prytanies, were not in the order presented here, as the Athenians determined the actual order of the Prytanies serving each year by lot.

In 404, the two calendars were aligned, with the beginning of the year at the same time. Once this occurred, the first four months of the Conciliar year had 36 days and the last six had 35, but this resulted in the Conciliar now being lunisolar, resulting in the need to add more days.

These calendars, with the exception that the first day of each calendar was the same, were never truly aligned given the different number of months. Regardless of how one attempts to align and examine the calendar, it is only an approximate. The calendar is often off by several months due to the way the Athenians determined its first new Moon after the solstice and the additional confusion caused by the use of intercalary years.