Of Time and Revolutions and New Beginnings
Revolutions and a Revelation
The duration of a solar year (from the perspective of we wee earthlings) is the time it takes our home planet to revolve around the sun, specifically 365 days, 5 hours, 48 minutes, and 46 seconds — thus, 11 minutes and fourteen seconds short of 365 1/4 days. We can almost line up solar (“sidereal”) years with our 365-day Julian calendar year by inserting an extra day one out of four years, which is what we do on “leap years,” where an extra day is added to February; however (there’s almost always a “however”), those 11 minutes and fourteen seconds that we are “short” (to get to six hours - one-fourth of a day) inexorably add up, and eventually one of those 29th days of February has to be elided for the solar years and Julian years to sync up.
The formula for whether a year is a leap year or not (beyond the standard once-every-four-years, when the year is precisely divisible by four — such as 2020, 2024, 2028, etc. — is that if the year is divisible by 100 (such as 1900), then an exception is made, and February will only have the standard 28 days — unless the year is also divisible by 400, in which case it is a leap year after all (such as the year 2000 was).
As a side note, the term “leap year” seems illogical. Within a leap year, you add a day, rather than leaping over a day. A day is inserted, not bypassed. Perhaps it should be called a “shove year” rather than a “leap year,” as another day is shoved between the normal end of February and the first day of March. So, for the upcoming year (this is being written 12/29/2023), we could say, “Take this year and shove it” — and only mean by that that February will have 29 days in it.Anyway, enough of that. With the Julian calendar, we know when the year begins: January 1st. But why January 1 of all days? That also makes no sense to me. Emotionally, Spring seems much more like the start of a new year, when “the first bud opes,” as Paul Laurence Dunbar put it in his poem Sympathy (which also contains the line, “I Know Why the Caged Bird Sings,” which Maya Angelou used as the title of one of her autobiographical books).
A solar year actually could begin any day or time. It's not tied to any given event, as equinoxes and solstices are. January 1st is an arbitrary (and, to me, irritating) date to use as the beginning of a year (or anything, for that matter). The winter solstice (December 21 or 22, several days before that) would make some sense as, following a six-month slide into ever colder days and darkness, it’s when days start getting longer again (in the sense of there being more sunlight). Even one of the equinoxes (Spring or Autumn) would make more sense than January 1 to start a new year with.
All of which brings us (how’s that for a serpentine segue?) into the topic of Intercalary Months. “Say what?” you say?
Intercalary months were “shove months” that Israelites of “Bible times” would insert into seven out of every 19 years. They used lunar months rather than Julian months of 30 or 31 days, with the occasional red-headed-stepchild month of 28 or 29 days included seemingly as an afterthought. But lunar months (like “Julian months”) also don’t sync up with solar years: no whole number of lunar months equals 365 days, 5 hours, 48 minutes, 46 seconds. So, the Israelites of old would insert an extra month seven times out of 19.
When I first read about intercalary months, it didn’t seem to add up (literally). My thought process was, “Lunar months are 30 days long, so each twelve-month year, being 360 days long (12 X 30 = 360), is approximately five days shorter than a solar year of around 365 1/4 days. So, to make up for it and sync up lunar months with solar years, a new month (of 30 days) needs to be added only approximately once every six years (6 x 5 = 30), not more than one-third of the time (7 of 19 = 37% of the time). In 19 years, inserting three additional months would be a lot more accurate than inserting seven.”
Since I had thought I knew that lunar months were 30 days long, the seven added lunar months would equal 210 days (7 X 30 = 210), which would be the equivalent of adding almost precisely 11 days, on average, each year, when only around five are needed (210 divided by 19 = 11.05).
But my calculations were off because I was working from the wrong premise: that lunar months are 30 days long. They’re not!
Lunar months don’t equate to a whole number of days any more than solar years equate to a whole number of months (of any stripe, lunar or Julian or what have you). Lunar months are actually very close to being 29.5 days in length. Now the math makes sense: 12 X 29.5 = 354, so twelve lunar months are approximately eleven days short of a solar year. Adding a lunar month seven times out of 19, for an average of 11 days per year, now “adds up.”
Who said math was boring? (If you’ve read this far, you apparently don’t think so).
