Juggling Calendars
In my day job, I develop and teach short courses in cybersecurity. Over the past couple of weeks, I’ve been overseeing a pilot offering for a new course, which implies nine- and ten-hour days at a minimum. This week in particular I’ve been “on the platform,” lecturing and leading classroom sessions. All of which is to say, I’ve been coming home in the evening and crashing hard rather than getting any writing done. Today was spent mostly just resting.
I did get one interesting task done today, though. Over the past few weeks, I’ve worked out an overall timeline to support the story of Alexandra’s adventures – essentially an alternate history of the Peloponnesian Wars. That’s a little coarse-grained, though, mostly just a bullet list of the most important handful of events to take place each year. Now that I’m getting close to starting to write, I need a more fine-grained timeline on which to hang the plot. Which means I spent today juggling calendars.
Most of the first novel is going to take place in and around Athens, in the years 416 BCE to 414 BCE. Alexandra is going to be involved in the life of the city, its religious festivals, civic observances, and political debates. All of which means I need to deal with the Athenian calendar. Unfortunately, there wasn’t a single, consistent, well-designed Athenian calendar.
The Athenians kept track of religious festivals with a lunar calendar, each year starting on the first new moon after the summer solstice, with 12-13 months per year. A fairly rigorous lunar calendar existed in the period I’m writing in, based on the calculations of an Athenian astronomer named Meton. However, the actual festival calendar seems to have been maintained by the city magistrates, who were not astronomers and just based an ad hoc reckoning on whenever someone spotted the new moon every month.
Meanwhile, during the period I’m working on, the Athenians maintained a completely separate solar calendar to keep track of the workings of the polis government. They broke the solar year (365 or 366 days) into ten roughly equal
Meanwhile, I’ve already invented my own calendar for Alexandra’s home country, the Etos Kosmou reckoning I mentioned in this post. Meanwhile, for my own sanity, I need to relate everything back to the Gregorian calendar so I can keep track of things.
It was actually a challenge to figure out the dates of new moons, full moons, and the four points of the solar year that far back in history. I spent an hour or two this afternoon messing with my usual planetarium software (a copy of Starry Night 7 Enthusiast), but that was kind of imprecise. Finally I found a couple of useful links:
Since both of those sources matched the few dates I had already worked out by hand, I felt inclined to put some trust in them. Those sources enabled me to quickly set up a spreadsheet comparing Athenian festival calendar, EK reckoning, and Gregorian reckoning for the roughly two-year period I need:
Off to the right, I have columns of the table marking (some) of the prytany beginning dates (important if I need the government to change hands, or for the timing of an
Neat exercise, this, and it should lend the story some verisimilitude. I can’t guarantee that this is exactly how the Athenians reckoned those two years in particular, but then their calendars were maintained on the fly. Since this is alternate history, a slightly different set of magistrates might very well have decided to arrange things differently. Hopefully, the result is good enough that any classical experts in the audience (all two of them) will let it pass.
(Whenever I write in this period, I keep having nightmares that involve Harry Turtledove reading the story and shaking his head sadly