Everything Everywhere Daily: History, Science, Geography & More - Leap Years and Leap Day

Episode Date: February 29, 2024

Once every 1461 days, sometimes, we have a day on the calendar that we don’t normally have.  This extra day is a necessity if our calendars are kept in sync with the orbit of the Earth around the Sun, but it also can cause problems with people and computers.  Nonetheless, whatever problems it might cause are far less than some of the alternatives, which would require leap weeks and even leap months.  Learn more about leap years and the significance of February 29 on this episode of Everything Everywhere Daily. Sponsors BetterHelp Visit BetterHelp.com/everywhere today to get 10% off your first month ButcherBox Sign up today at butcherbox.com/daily and use code daily to choose your free steak for a year and get $20 off."  Subscribe to the podcast!  https://link.chtbl.com/EverythingEverywhere?sid=ShowNotes -------------------------------- Executive Producer: Charles Daniel Associate Producers: Peter Bennett & Cameron Kieffer   Become a supporter on Patreon: https://www.patreon.com/everythingeverywhere Update your podcast app at newpodcastapps.com Discord Server: https://discord.gg/UkRUJFh Instagram: https://www.instagram.com/everythingeverywhere/ Facebook Group: https://www.facebook.com/groups/everythingeverywheredaily Twitter: https://twitter.com/everywheretrip Website: https://everything-everywhere.com/ Learn more about your ad choices. Visit megaphone.fm/adchoices

Once every 1,461 days, sometimes, we have a day on the calendar that we don't normally have, leap day. This extra day is a necessity if our calendars are to be kept in sync with the orbit of the Earth around the sun, but it can also cause problems with people and computers. Nonetheless, whatever problems it might cause are far less than some of the alternatives, which would require leap weeks and even leap months. Learn more about leap years and leap day, and the significance of February 29th, on this episode of Everything Everywhere Daily.

What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. If you've listened to this podcast long enough, you know that I have a thing for calendars. I've done episodes on everything from how we got the days of the week to the Gregorian calendar

to the months. So there is no way that I was going to let February 29th go by without doing an episode on it, especially considering that this is the first February 29th that I've experienced since starting this podcast. I've touched on why there is a February 29th in previous episodes, but let me briefly restate the reason for it here. The problem is that our basic units of time, the day in the year, are determined by astronomical events. events, which are not evenly divisible by each other. I've read many different proposals for different calendar systems, and while some of them do have their merits, they can't escape this fundamental problem. Days do not divide evenly into a solar year. Our current calendar, the Gregorian

calendar, is based on a solar year. That means it tries to get the seasons and the solar events, such as the solstices and the equinoxes at the same time each year. However, the Gregorian The Gregorian calendar was a modification of the Julian calendar, and the Julian calendar was designed to replace the Roman calendar, which was truly awful. I've done a lot of episodes on Roman history and how many things in our modern world can be traced back to ancient Rome. However, the original ancient Roman calendar was well and truly one of the dumbest things ever invented.

The original Roman calendar had ten months, the first of which was March and the last of which was December. In fact, the word December means the 10th month, which is now very odd considering it's the 12th months. But between December and March, there was nothing. There were 61 days totally unaccounted for in the calendar. Again, I'm not sure how one develops a calendar and not account for all the days in the year, but the very early Romans did exactly that. Eventually, those 61 days were taken up by two more months, January and February.

but there were still massive problems with the calendar. The calendar didn't correspond to the solar year, and after several centuries, they were celebrating their harvest festival in the spring. This was solved by Julius Caesar, who instituted a new solar calendar that solved the problems of the old Roman calendar. The calendar of Julius Caesar, known as the Julian calendar,

was a pretty good calendar considering what it replaced. The calendar was actually the idea of sociogenesies, of Alexandria. It had been known for centuries that a solar year was approximately 365 and one-quarter days. That quarter-day was resolved in the Julian calendar by adding an additional day every fourth year. There would be 365 days every year, and then on the fourth year there would be 366 to take care of that quarter day that made up a year. I don't want to rip on the Julian calendar too much, because it truly was a revolutionary development. However, the Julian calendar wasn't perfect.

If you listen to what I said before closely, a solar year is approximately 365 and one quarter days long. And the approximately part is key. A more exact value is that a solar year is 365.2422 days long. That might not seem like much of a difference, but it becomes an issue after many centuries. Very slowly, the calendar began to misalign with the solar year. This error was resolved with a calendar which was championed by Pope Gregory the 13th.

He proposed a new calendar that was very close to the Julian calendar, but made a few modifications. To compensate for the errors in the Julian calendar, every year divisible by 100 would not be a leap year. And that would fix most of the problems. but it still left an error so they made an additional change that if the year was divisible by 400, then it would be a leap year. So the year 1900 was not a leap year, but the year 2000 was a leap year. That got the calendar pretty close to the solar year, close enough that it would correspond to the solar year for thousands of years.

And just as an aside, it will probably be necessary to make a change to the calendar before the year 4,000, such that any year evenly divisible by 4,000 would not be a leap year. And if you really want to get pedantic, there will probably also have to make another change such that if the year is evenly divisible by 20,000, then it is a leap year. The point of all this is that the added day once every four years is sort of just a shim on the calendar to make it work. It's technically known as an intercalary day. There have been many proposed calendars, but no matter the system that's been proposed, there has to be some sort of interchillary period somewhere to make the days fit a year

if you want to make the calendar approximate a solar year. For example, a strict lunar calendar like the Islamic calendar has no intercalated period at all, and that's why a holiday like Ramadan can fall on any month over a period of years. The Jewish calendar is a loony solar calendar. It follows the phases of the moon, but also tries to keep the months at roughly the same time of year. And they're able to do this because they have entire leap months to even things out. There are proposed calendar such as the Henke-Henry permanent calendar. This calendar would put the number of days at 364, a number which is nicely divisible by many other numbers.

Under this calendar, every month would have 30 days, save for the last month in each quarter, which would have 31. It would also then allow for every day on the calendar to correspond to the exact same day of the week every year. So in the Hinky Henry Permanent Calendar, January 1st would always be on a Monday every single year. However, this calendar would be off by approximately one and a quarter days every year. To get around this problem, every five or six years, there would be an entire leap week. This leap week wouldn't belong to any month, it would just be its own. thing. So we got an extra day every four years and it's something that we're going to have to deal with. For the most part, adding a day every four years is not a problem for most computers. In fact,

adding one day to an already existing month is computationally much easier than adding a leap week or a leap month that isn't associated with any current month. That being said, every four years, there are computer programs that fail when February 29th arrives. Most programming languages have libraries that you can reference that can handle leapier just fine, but sometimes they're used incorrectly or the programmer just forgets about leapiers. In 2016 alone, a host of bugs were found on many devices. Cars made by the Jeep Corporation had their clocks reset automatically on February 29th because they couldn't handle the date. The Dusseldorf International Airport had a problem with its baggage handling system,

which resulted in 1,200 pieces of luggage, not getting. getting on planes. The United States Postal Service had issues with their website where it couldn't handle February 29th. Apple's iOS and watchOS had an issue where their calendar preview feature didn't work on leap day. These are all pretty minor issues, but it's one of those things that constantly creeps up every single year. One of the longest running leap year bugs in computing has to do with Microsoft Excel. Ever since Excel was released for the Macintosh in 1985, it's had a bug where it thought the year 1900 was a leap year. The reason for the bug is that Excel was designed to be backwards compatible with Lotus

123, which used to be the dominant spreadsheet program at the time, and Lotus 123 had that bug. In the almost 40 years since Excel has been on the market, the bug has never been fixed. Not only has the bug never been fixed, but the bug is now codified in the ECMA Open Office XML-specific. So, if you create a spreadsheet that uses dates from the year 1900, it will create a date February 29, 1900, that never existed. However, to be fair, when I tried doing this on Google sheets, it did not create February 29, 1900. The other big issue with leap years is the reoccurring events that can happen during them. In other words, birthdays. I had an uncle who was born on February 29th, and I have another friend who's a leap year baby as well.

Shout out to Pete Nikolai. The odds of being born on February 29th is won in 1461. Most people with birthdays on February 29th will usually celebrate it on February 28th or March 1st, because that would be approximately when one year has passed. However, they would only have a birthday anniversary once every four years. The issue of leap year birthdays was a significant plot point in the Gilbert and Sullivan musical The Pirates of Panzance. In it, Frederick, the pirate apprentice, discovers that he's bound to serve the pirates until his 21st birthday.

In the play, this is interpreted by the pirates to mean that he is bound to serve until he is 88 years old, since the year 1900 was not a leap year, rather to serve until he was 21. Each legal jurisdiction has different rules for how they handle February 29th. Generally speaking, in the United States, when things are defined in terms of days, February 29th is just treated as a regular day. For example, if you had a non-compete clause that lasted one year and began on March 1st, and the next year was a leap year, that non-compete clause would last for 366 days, not 365 days. However, if things are defined in terms of years, then leap years are usually ignored because they aren't really relevant.

There are a host of cultural traditions associated with February 29th as well. According to tradition, in 5th century Ireland, St. Bridget lamented to St. Patrick that women were not allowed to propose marriage to men. So, St. Patrick allowed February 29th to be the one day when women could propose marriage or ask a man to dance. In some places, February 29th became known as Bachelor's Day for this reason. This tradition was mostly held in Ireland and Scotland, but it was also celebrated in the United States in the early 19th century. February 29th in leap year are necessary to make our country. calendar's function. But this necessity always ends up with computer bugs, misunderstandings, and unique circumstances every four years. The executive producer of Everything Everywhere

Daily is Charles Daniel. The associate producers are Peter Bennett and Cameron Kiefer. Today's review comes from listener D with Atilda over on Apple Podcasts in the United States. They write, Super, I finally did it. I listened to hundreds of episodes on double speed and I met my goal of joining the Completionist Club before the start of the Super Bowl. I love the show. This podcast satisfies my desire to learn something new every day while also not taking too long, as I listen to lots of other podcasts as well. It's one of the few podcasts that I insist on listening to on the day of release. Looking forward to hundreds more episodes, Salud. Well, thanks, D with Atilda, and I would like to formally welcome you to the Completionist Club. As always, please make

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