History of calendars

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The history of calendars spans several thousand years. The origins of the modern Gregorian calendrical system date to ancient Sumer, where the sexagesimal system was invented. Many different calendars are still in use today; the Gregorian calendar is most widely used.

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[edit] Early calendars

[edit] Sumer

The ancient Sumerian calendar divided a year into 12 lunar months of 29 or 30 days.[1] Each month began with the sighting of a full moon. Sumerian months had no uniform name throughout Sumeria because of the religious diversity. This resulted in scribes and scholars referring to them as "the first month", "the fifth month" etc. To keep the lunar year of 354 days in step with the solar year of 365.25 days, an extra, intercalary month was added every three years or so, much like a Gregorian leap year.

There were no weeks in the Sumerian calendar. Holy days and time off from work were usually celebrated on the first, seventh and fifteenth of each month. In addition to these holy days, there were also feast days which varied from city to city. A day was divided into twelve hours, six daylight hours, each lasting one-sixth of the day, and six nighttime hours, each lasting one-sixth of the night. This meant the length of hours varied from season to season, daylight hours being shorter in the winter and longer in the summer and vice versa.[2][3]

[edit] Maya

Main article: Mayan calendar

Of all the ancient calendar systems, the Maya and other Mesoamerican systems are the most complex. The Mayan calendar had 2 years, the 260-day Sacred Round, or tzolkin, and the 365-day Vague Year, or haab.

A modern pictogram of the Mayan god Ahau, after which the 20th day of the tzolkin cycle was named
A modern pictogram of the Mayan god Ahau, after which the 20th day of the tzolkin cycle was named

The Sacred Round of 260 days is composed of two smaller cycles: the numbers 1 through 13, coupled with 20 different day names, mostly the names of gods: Imix, Ik, Akbal, Kan, Chicchan, Cimi, Manik, Lamat, Muluc, Oc, Chuen, Eb, Ben, Ix, Men, Cib, Caban, Eiznab, Cauac, and Ahau. The Sacred Round was used to determine important activities related to the gods and humans: name individuals, predict the future, decide on auspicious dates for battles, marriages, and so on.

The two cycles of 13 and 20 intermesh and are repeated without interruption: the cycle would begin with 1 Imix, then 2 Ik, then 3 Akbal and so on until the number 13 was reached, at which point the number cycle was restarted so 13 Ben would be followed by 1 Ix, 2 Men and so on. This time Imix would be numbered 8. The cycle ended after 260 days, with the last day being 13 Ahau.

The Vague Year of 365 days is similar to our modern calendar, consisting of 18 months of 20 days each, with an unlucky five day period at the end. The Vague Year had to do primarily with the seasons and agriculture, and was based on the solar cycle. The 18 Maya months are known, in order, as: Pop, Uo, Zip, Zotz, Tzec, Xuc, Yaxkin, Mol, Chen, Yax, Zac, Ceh, Mac, Kankin, Maun, Pax, Kayab and Cumku. The unlucky five-day period was known as uayeb, and was considered a time which could hold danger, death and bad luck.

The Vauge Year began with the month of Pop. The Maya 20-day month always begins with the seating of the month, followed by days numbered 1 to 19, then the seating of the following month, and so on. This ties in with the Maya notion that each month influences the next. The Maya new year would start with 1 Pop, followed by 2 Pop, all the way through to 19 Pop, followed by the seating of the month of Uo, written as 0 Uo, then 1 Uo, 2 Uo and so on. These two cycles coincided every 52 years. The 52-year period of time was called a "bundle" and was similar to a modern day century.[4][1]

[edit] Greece

The ancient Athenian calendar was a lunisolar calendar with 354 day years, consisting of twelve months of alternating length of 29 or 30 days. To keep the calendar in line with the solar year of 365.25 days, an extra, intercalary month was added in every other year.[5] The Athenian months were called Hekatombion, Metageitnion, Boedromion, Pyanepsion, Maimakterion, Poseidon, Gamelion, Anthesterion, Elaphebolion, Munychion, Thargelion, and Skirophorion.[6] The intercalary month usually came after Poseidon, and was called second Poseidon.[7]

In addition to their regular, "festival" calendar, the Athenians maintained a second, political calendar . This "conciliar" calendar divided the year into "prytanies", one for each of the "phylai", the subdivisions of Athenian citizens. The number of phylai, and hence the number of prytanies, varied over time. Until 307 BCE, there were 10 phylai. After that the number varies between 11 and 13 (usually 12). Even more confusing, while the conciliar and festival years were about the same length in the 4th century BCE, such was not regularly the case earlier or later. documents dated by prytany are frequently very difficult to assign to a particular equivalent in the Gregorian calendar.[7]

[edit] See also

[edit] References

  1. ^ a b Bellis, Mary. History of Clocks and Calendars. About.com. Retrieved on 2007-12-06.
  2. ^ Sumarian Astronomy and Calendars. Ellie Crystal's Metaphical and Science Web Site. Retrieved on 2008-04-05.
  3. ^ History of Astronomy. ephemeris.com. Retrieved on 2008-04-05.
  4. ^ Maya civilization. Civilization.ca. Retrieved on 2008-04-03.
  5. ^ Early Greek Calendars. An Introduction to Calendars. Retrieved on 2008-04-05.
  6. ^ (1911) Ginzel: Handbuch der Mathematischen und Technischen Chronologie 2. Germany: F.K., 335-336. 
  7. ^ a b The Ancient Greek Calendar. A History of the Western Calendar. Retrieved on 2008-04-05.