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The Permeance of Calendars

Google Calendar, digital or physical (if you’re lame enough to still write in them), where would we be without our handy pockets of the year? From mapping celebrations, to tracking agricultural seasons and avoiding bad omens, Sophie Poredos dives deep into the history of the ancient calendars that ebbed and flowed with political changes. 

Julian Calendar – Julian or Gregorian, which calendar would you pick? 

This is probably the only non-existent one you’re familiar with. The Julian calendar was introduced by Julius Caesar as a reform of the Roman republican calendar. Its predecessor was three months ahead of the solar calendar, and so Julius’ trusty astrologer, Sosigenes, divided each year into 12 months, with repeating leap years. However, there was a bit of a hiccup in this plan, an entire 11 minutes and 14 seconds were overestimated resulting in a discrepancy of 13 days. Eventually, this was fixed, but even today you’ll find Caesar-approved calendars used to track the liturgical dates that move each year, such as Easter.[1]

 Byzantine Calendar – Old Russian/Serbian 


You’ve probably heard of Constantinople (known now as Istanbul). Basically, Roman Emperor Constantine the Great founded this ancient city, that is now modern-day Türkiye. Around this same time, the Byzantine Calendar was introduced, in around 988 to 1453 AD.[2] The Eastern Orthodox Church was a big fan of this Calendar as – unlike its Greek counterparts – it tried to establish the years counted between the creation of the world and Jesus Christ’s estimated birth, which, by the way, was 5508 years. Ancient scholars remarked on the significance of the Byzantine Calendar; its astrological lunar and solar chartered cycles could be used to determine influential dates, such as Easter, as well as to recognise their cosmic significance. However, we wave goodbye to this ‘Old Russian’ calendar, as it got dropped by Peter the Great in 1700 AD in preference to the Julian Calendar, though some Orthodox Christians still use the Byzantine calculation of the Earth’s creation date.[3]


Babylonian Calendar – (Not related in any way to the movie with Margot Robbie)


Now our deep-dive leads us to a much more ancient civilisation. The Babylonian calendar was lunisolar, with 12 months that included an extra leap month as decided on by the King.[4] This calendar shares great similarities with the Jewish calendar and the calculation of Easter, as they both implement the Metonic cycle, or planning of the New Year to fall before the spring equinox.[5] For all the moon crystal cleansing girlies out there, this calendar was also used for ritualistic purposes to worship Babylonian Gods, as protection for their community as well as to maintain these divine relationships.[2]


Unfortunately, dark days appear around the 4th-5th century BC for this calendar. A much more efficient system resulting in the Athenian Calendar, which balanced these leap days, was founded by Aristotle’s pupil after Alexander the Great captured Babylon. Four months later, the Babylon calendar ceased to remain in operation.[4] [5] 

Gezer Calendar – shoutout to this little guy! 


One of the earliest human calendars, the Hebrew calendar dated around the 10th century BCE. This humble limestone tablet just had to make my list. What could people possibly have been tracking before the invention of the Taylor-Swift-ticket-sport? Agriculture, it turns out. Transcribed from the earliest form of written Hebrew text, this calendar tracked monthly or bimonthly periods relating to farming. Discovered near Jerusalem, this text follows a structure that is equivalent to a schoolboy song;

"Two months of harvest”

"Two months of planting”

"Two months are late planting”

"One month of hoeing”

"One month of barley-harvest”

"One month of harvest and festival”

"Two months of grape harvesting”

"One month of summer fruit”[6]


Why did I decide to tell you about boring, dusty old calendars? Well, humans are funny little things.

We love to tell stories and track our rituals, agricultural seasons, and celebrations like every generation did before us. Every calendar holds a rich history of our life and the creative aspirations of those who formed them. Every creator and astrologer believed that, finally, they had perfected the art. This ongoing transformation of how we tell time proves how mundane our concept of passing time is; it literally has changed every few centuries. Stop fretting over your lack of achievements or goals this year, time is not as permanent as it appears. On that note, let’s make a petition to go back to adding in a leap month as needed, I could really use the catch up for uni assignments. 


[1] T. Editors of Encyclopaedia (2019), ‘Julian calendar’, Britannica, accessed 13th April 2023,

[2] Da Riva, R. (2019), ‘What Sorts of Rituals Really Went on Inside Late Babylonian Temples?’, asor, accessed 14th April 2023,

[3] ‘Byzantine Creation Era Calendar’, OrthoChristian, accessed 14th April 2023,


[4] Van Gent, R.H (2021), ‘The Babylonian Calendar’, webspace science, accessed 12th April 2023, 


[5] ‘Calendar, Babylonian’ (2020), livius, accessed 12th April 2023,


[6] Timur 2022, ‘Old Russian (Byzantine) system of chronology’, PLANETCALC, accessed 12th April 2023,



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