Day 875: Why History Is Missing 10 Days (Plus The Weird Story Of February 30)

originally published May 24, 2014

One day in the mid-1570’s, a Calabrian doctor named Aloysius Lilius deduced precisely how grotesquely wrong our calendar was. We had spent centuries dragging along this defective Ancient Roman relic known as the Julian calendar, completely mucking up the proper documentation of history. Easter wasn’t landing where it was supposed to, according to the original blueprints laid out by the First Council of Nicaea in 325 AD, and the spring solstice was showing up around March 11. Everything was, to put it in the parlance of the times, wack.

Lilius was given the thumbs-up from Pope Gregory XIII to sink his knuckles into the pasty goo of calendar reform. This was a huge deal, big-picture-wise, though its impact on the general populace was minor enough that a change was feasible. Folks weren’t as clingy to their calendars as we are today. Adjusting the calendar system wouldn’t affect prime-time television schedules, Super Bowl year numberings or even milk expiry dates (since at the time, the expiry date for most any perishable item was “right fucking away”).

And so began the most radical tweak of our datebooks in over a millennium, the last major adjustment to be overseen by the church and possibly the final and most accurate solution we’ll ever see. Possibly. But I don’t know if we want to go through something like this again.

The biggest problem with the Julian Calendar was its inaccurate calculation of the year’s length. 365.25 days is an easy and pretty number to use; it gives us a leap year every four years and that’s that. Except the equinoxes weren’t behaving. Lilius determined that the year is actually 365.2524 days long, and he proposed a rather elegant solution. In order to account for the 0.002% correction necessary to keep the equinoxes where they’re supposed to be, we’d just skip leap day (February 29) on years ending in a ‘00’, except for every 400 years. The elimination of those three days every four centuries would keep the system working. This is why there was no February 29 in 1900, but there was one in 2000.

It was brilliant. Pope Gregory was ecstatic. Lilius even figured out how to gently spool his calculations into the public realm without causing too much of a hullabaloo. Given that the Julian calendar was ten days off where it should be, Lilius proposed simply skipping the next ten leap days, which would tuck the new calendar snugly into accuracy in the next 40 years. Lilius died before the reform could be instituted, and mathematician/astronomer Christopher Clavius, who picked up the reins on the project, insisted we do it right away. Ten days were to be wiped from the calendar at once.

Thursday, October 4, 1582 was followed by Friday, October 15. Just like that. The days of the week weren’t altered, but I imagine the following weekend was downright packed with birthday parties for everyone whose special day was glossed over in the ten-day shift. The number of sick days taken on Monday, October 18 due to hangovers (known then as an abundance of pukey-humors) must have been astounding.

This wasn’t a global shift, mind you. Spain, Portugal, the Polish-Lithuanian Commonwealth and most of Italy hopped on board right away. This new calendar was credited to the brain-trust of Pope Gregory (hence the name ‘Gregorian Calendar’), and the Catholic nations were quick to adopt it as the new standard. The Spanish and Portuguese colonies climbed in once word travelled to them, and eventually all the Catholic countries were on Gregorian time. France followed their December 9, 1582 with December 20, which must have really cranked up the pressure to buy Christmas gifts.

Other, less-Catholic lands weren’t quite as impressed.

Lands which fell under Protestant rule felt that this new proposed calendar might be nothing more than a subversive plot to lure unsuspecting people into the Catholic fold. Eliminating ten days? Clearly a conspiracy to get everyone to eat fish on Fridays… right? It took more than a century before Danish astronomer (and the first to measure the speed of light, so he had some scientific street-cred) Ole Rǿmer was able to talk the Protestants into considering the switch.

It’s never a good thing when a religious bias and illogical hatred of another group nudges in front of science and reason and insists on backward-thinking as the dominant model. But here was a thing as simple and innocuous as an accurate calendar that would place the equinoxes and important holidays where they were meant to be, and it took centuries to get everyone on board. And don’t even get me started on Sweden.

Sweden was ready to make the shift from Julian to Gregorian in 1700, by which time (because the Julians celebrated February 29, 1700 while the Gregorians did not) their calendar was eleven days out. But rather than make the same band-aid-rip adjustment that Christopher Clavius had talked the pope into executing, they opted for the gradual leap-day elimination over the next eleven leap years. This would mean Sweden’s calendar for most of the next half-century would be out of step with the rest of the planet’s.

To make things worse, everyone got distracted by a Scandinavian war and Sweden wound up forgetting to skip February 29 in both 1704 and 1708. This country just couldn’t get their temporal shit together. For 1712, it was decided by King Charles XII that Sweden would simply revert back to the Julian calendar, and in order to do so they needed an extra day to make up for the skipped February 29 in 1700. The solution? February 30. For one year and one year only, Sweden stretched our shortest month to 30 days.

It took even longer for the rest of the world to catch on. The British Empire (which at the time included the colonies that would eventually become America) followed Wednesday, September 2, 1752 with Thursday, September 14. Alaska, which was under Russia’s domain until 1867, didn’t shift over until then. At the same time, the International Date Line was shifted from Alaska’s eastern border to its western one, so they only had to shift eleven days instead of the requisite twelve by that time (thanks to February 29, 1800). Friday, October 6 was followed by another Friday, October 18. Might have been kinder to do that on a weekend.

Russia’s famous October Revolution of 1917 actually took place on November 7-8, but was given that title because it happened in October according to the Julian calendar. Russia slipped into Gregorian mode in January of the following year, skipping 13 days. Bulgaria made the switch in 1916 (a good way to speed up the World War, I guess), and finally Greece changed over in February of 1923. The Orthodox religions of Eastern Europe – who don’t give two shits about Pope Gregory or his calendarian madness – never changed.

Fortunately, we probably won’t see another calendar shift anytime soon. Where the Julian calendar would lose a day of accuracy every 128 years, we’re now good with only losing a day every 3300 years. Of course, eventually we’ll need to account for that…

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s