5 Dates You Won't Find on Your Calendar

ThinkStock/Erin McCarthy
ThinkStock/Erin McCarthy

While you may be a bit fuzzy on which months have 30 days and which have 31, it’s safe to say you’re pretty familiar with the months and days of the year. But due to unusual record-keeping practices or because of months that were eliminated over the centuries, there are a few days you’ll never see on your joke-a-day calendar.


At midnight every New Year’s Eve, we go from December 31 to January 1. Simple, right? That’s how it works for everyone ... except astronomers. Each year, astronomers keep track of the movements of various planets and stars, which are compiled into what’s called an ephemeris. While it’s useful for things like space travel and positioning telescopes, GPS systems also use the data to properly function.

The thing about ephemerides (the plural of ephemeris) is that they don’t reference any year other than the one for which they were written. So if you had an ephemeris for the year 2000, you wouldn’t find any mention of 1999 or 2001. Generally speaking, it shouldn’t be necessary, though, since it’s only for that particular year anyway.

Except when you referenced January 1, that is. Because some more detailed ephemerides will list the previous day’s celestial positions for reference purposes, the ephemeris would have to have information for December 31. But, since the ephemeris doesn’t refer to any other year, this date will instead often be called January 0. Going back to our year 2000 example, an ephemeris for that year might list Prince’s favorite day, December 31, 1999, as January 0, 2000 instead.

It’s worth noting that many modern day ephemerides have dropped the use of January 0 entirely, but there are others that still use it.

And back in the 1920s, several groups lobbied for a calendar with 13 months, each with four weeks. To reach 365 days, their plan was to add "January 0."


You may have a friend or relative in your life whose birthday is February 29. Maybe they fudge it and celebrate on February 28 or March 1 every year, or possibly they just have a mega-party every four years. (Or they have a mega-party every year, because why not.) So imagine how frustrating it’d be to have been born in the Swedish Empire on February 30, 1712, the only day of its kind in history.

Naturally, it was a pretty complex set of events that led to February 1712 getting two leap days. Our modern, Western calendar is called the Gregorian calendar, which was developed under Pope Gregory XIII. It’s basically just a series of improvements to the Julian calendar, created by Julius Caesar.

While the Gregorian calendar was completed in 1582, adoption by many countries was slow, so it took over 100 years for the Swedish Empire (which was primarily Protestant and not Catholic) to adopt it. Because the Julian to Gregorian swap included a difference of ten days, many regions simply skipped their calendar ahead a week and a half. The Swedish Empire decided to roll out the difference more gradually, and intended to skip leap days for forty years, starting in 1700, until the calendar was finally correct.

Except that didn’t happen because, shortly afterward, war broke out and everyone forgot about the leap days until 1712, when Sweden’s King, Charles (or Karl) XII, declared that they would forget about the Gregorian calendar and just switch back to the Julian instead. Since they did manage to skip one leap day, in 1700 (which was a leap year under the Julian calendar, but not the Gregorian), they simply decided to add it back onto the calendar that February—meaning that February 1712 had two leap days according to Sweden’s calendar, which gave them the only February 30 in history. (Sweden finally went through with the Gregorian switch in 1753 and just skipped ahead a few days, like everyone else.)

3. MARCH 0

While you could think of February 30 as some weird kind of March 0, they’re not the same thing (though they do both involve leap years). If someone asked you what the day before March 1 is, you’d probably ask them, “What year?” March 0 is, like January 0, simply a reference to the day before it, but it’s useful since March 0 can be either February 28 or 29, depending on the year.

While this is occasionally used in software (some old versions of Microsoft Excel will accept 3/0 as a date and simply plug in the correct day for the particular year, for example), it’s more commonly found in something known as the Doomsday rule.

It sounds fairly ominous, but the Doomsday rule is just a method for calculating what day of the year falls on for any given date. For example, by following the Doomsday rule, you could quickly tell that January 19, 1481 was a Wednesday. How? By figuring out what creator John Conway calls “the Doomsday.” This is the day of the week that certain calendar days will always fall on in a given year. April 4, June 6, and August 8 are just a few days of the year that will always fall on that year’s Doomsday. Another big one? March 0, i.e., the final day of February.

So, using 1481 as our example again, you can use a formula to determine that its Doomsday was Monday. (For the record, 2013’s Doomsday is Thursday.) From there, we could quickly ascertain that March 0 was a Monday, and for that particular year, February only had 28 days (since it was not a leap year), making “March 0” Monday, February 28, 1481. If you’re mathematically-minded, it’s a fun challenge. If you’re not, well, you can always look the day up on the internet or use a Doomsday calculator.


There aren’t just odd and unusual days of the year. There are entire months as well. Remember the episode of The Simpsons where the school ordered faulty calendars with a 13th month (called Smarch)? Well, as it happens, we kind of had that once upon a time—namely, those left over from the days of the Roman calendar, which preceded the aforementioned Julian calendar. Much like how the process of moving from the Julian calendar to the Gregorian calendar left a few odd days out, the move from the Roman calendar to the Julian one actually added some.

These days, 67 in all, were then added into a pair of months between the November and December of 45 BC, and were referred to as intercalaris prior and intercalaris posterior, which are often called Undecimber (pronounced like “oon,” not “uhn”) and Duodecimber in modern days.

These names refer to the fact that December is named after the Latin word for ten (which itself came from the fact that the Roman calendar originally only had ten months and not twelve), while the Latin words for eleven and twelve (or in this case, thirteen and fourteen) are undecim and duodecim.

What’s more, the terms have even come to be used in modern computing. The Java programming language includes support for a 13-month calendar, and it refers to the 13th month as Undecimber.


Speaking of the Roman calendar, by the time Julius Caesar came along, it hadn’t had ten months for quite a while. Nearly 600 years, in fact. The Roman calendar that Caesar reformed was itself a reformed calendar constructed by King (not Emperor) Numa Pompilius sometime in the 7th century BC.

Prior to Pompilius’ changes, the Roman calendar, as we mentioned, had ten months: Martius, Aprilis, Maius, Iunius, Quintilis, Sextilis, September, October, November, and December. (Quintilis was later renamed Julius after Julius Caesar himself, while Sextilis was changed to Augustus in honor of his son/grand-nephew, Caesar Augustus.) King Numa Pompilius added Januarius and Februarius, giving us the twelve months we have today … except he also added another, forgotten month that hasn’t been in use for millennia: Mercedonius.

Mercedonius was a kind of a leap month, situated between Februarius and Martius, and was approximately 27 days. Although there was apparently some kind of formula to determine in which years Mercedonius was used and in which years it wasn’t, the implementation was spotty, since it was up to whoever the current Pontifex Maximus was at the time to decide if the month was used or not.

Since the month was used so sloppily, Julius Caesar simply eliminated it entirely when constructing the Julian calendar, rearranged the days throughout the year, and made a simple, easy-to-follow leap day system.

Looking to Downsize? You Can Buy a 5-Room DIY Cabin on Amazon for Less Than $33,000

Five rooms of one's own.
Five rooms of one's own.

If you’ve already mastered DIY houses for birds and dogs, maybe it’s time you built one for yourself.

As Simplemost reports, there are a number of house kits that you can order on Amazon, and the Allwood Avalon Cabin Kit is one of the quaintest—and, at $32,990, most affordable—options. The 540-square-foot structure has enough space for a kitchen, a bathroom, a bedroom, and a sitting room—and there’s an additional 218-square-foot loft with the potential to be the coziest reading nook of all time.

You can opt for three larger rooms if you're willing to skip the kitchen and bathroom.Allwood/Amazon

The construction process might not be a great idea for someone who’s never picked up a hammer, but you don’t need an architectural degree to tackle it. Step-by-step instructions and all materials are included, so it’s a little like a high-level IKEA project. According to the Amazon listing, it takes two adults about a week to complete. Since the Nordic wood walls are reinforced with steel rods, the house can withstand winds up to 120 mph, and you can pay an extra $1000 to upgrade from double-glass windows and doors to triple-glass for added fortification.

Sadly, the cool ceiling lamp is not included.Allwood/Amazon

Though everything you need for the shell of the house comes in the kit, you will need to purchase whatever goes inside it: toilet, shower, sink, stove, insulation, and all other furnishings. You can also customize the blueprint to fit your own plans for the space; maybe, for example, you’re going to use the house as a small event venue, and you’d rather have two or three large, airy rooms and no kitchen or bedroom.

Intrigued? Find out more here.

[h/t Simplemost]

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10 Facts About Real Genius On Its 35th Anniversary

Val Kilmer stars in Martha Coolidge's Real Genius (1985).
Val Kilmer stars in Martha Coolidge's Real Genius (1985).
Sony Pictures Home Entertainment

In an era where nerd is a nickname given by and to people who have pretty much any passing interest in popular culture, it’s hard to imagine the way old-school nerds—people with serious and socially-debilitating obsessions—were once ostracized. Computers, progressive rock, and role-playing games (among a handful of other 1970s- early '80s developments) created a path from which far too many of the lonely, awkward, and conventionally undateable would never return. But in the 1980s, movies transformed these oddballs into underdogs and antiheroes, pitting them against attractive, moneyed, successful adversaries for the fate of handsome boys and pretty girls, cushy jobs, and first-place trophies.

The 1985 film Real Genius ranked first among equals from that decade for its stellar cast, sensitive direction, and genuine nerd bona fides. Perhaps fittingly, it sometimes feels overshadowed, and even forgotten, next to broader, bawdier (and certainly now, more problematic) films from the era like Revenge of the Nerds and Weird Science. But director Martha Coolidge delivered a classic slobs-versus-snobs adventure that manages to view the academically gifted and socially maladjusted with a greater degree of understanding and compassion while still delivering plenty of good-natured humor.

As the movie commemorates its 35th anniversary, we're looking back at the little details and painstaking efforts that make it such an enduring portrait not just of ‘80s comedy, but of nerdom itself.

1. Producer Brian Grazer wanted Valley Girl director Martha Coolidge to direct Real Genius. She wasn’t sure she wanted to.

Following the commercial success of 1984’s Revenge of the Nerds, there was an influx of bawdy scripts that played upon the same idea, and Real Genius was one of them. In 2011, Coolidge told Kickin’ It Old School that the original script for Real Genius "had a lot of penis and scatological jokes," and she wasn't interested in directing a raunchy Nerds knock-off. So producer Brian Grazer enlisted PJ Torokvei (SCTV) and writing partners Babaloo Mandel and Lowell Ganz (Splash, City Slickers) to refine the original screenplay, and then gave Coolidge herself an opportunity to polish it before production started. “Brian's original goal, and mine, was to make a film that focused on nerds as heroes," Coolidge said. "It was ahead of its time."

2. Martha Coolidge’s priority was getting the science in Real Genius right—or at least as right as possible.

In the film, ambitious professor Jerry Hathaway (William Atherton) recruits high-achieving students at the fictional Pacific Technical University (inspired by Caltech) to design and build a laser capable of hitting a human-sized target from space. Coolidge researched the subject thoroughly, working with academic, scientific, and military technicians to ensure that as many of the script and story's elements were correct. Moreover, she ensured that the dialogue would hold up to some scrutiny, even if building a laser of the film’s dimensions wasn’t realistic (and still isn’t today).

3. One element of Real Genius that Martha Coolidge didn’t base on real events turned out to be truer than expected.

From the beginning, the idea that students were actively being exploited by their teacher to develop government technology was always fictional. But Coolidge learned that art and life share more in common than she knew at the time. “I have had so many letters since I made Real Genius from people who said, 'Yes, I was involved in a program and I didn’t realize I was developing weapons,'" she told Uproxx in 2015. “So it was a good guess and turned out to be quite accurate.”

4. Val Kilmer walked into his Real Genius audition already in character—and it nearly cost him the role.

After playing the lead in Top Secret!, Val Kilmer was firmly on Hollywood’s radar. But when he met Grazer at his audition for Real Genius, Kilmer decided to have some fun at the expense of the guy who would decide whether or not he’d get the part. "The character wasn't polite," Kilmer recalled to Entertainment Weekly in 1995. "So when I shook Grazer's hand and he said, 'Hi, I'm the producer,' I said, 'I'm sorry. You look like you're 12 years old. I like to work with men.'"

5. The filmmakers briefly considered using an actual “real genius” to star in Real Genius.

Among the performers considered to play Mitch, the wunderkind student who sets the movie’s story in motion, was a true genius who graduated college at 14 and was starting law school. Late in the casting process, they found their Mitch in Gabriel Jarrett, who becomes the third generation of overachievers (after Kilmer’s Chris and Jon Gries’s Lazlo Hollyfeld) whose talent Hathaway uses to further his own professional goals.

6. Real Genius's female lead inadvertently created a legacy for her character that would continue in animated form.

Michelle Meyrink, Gabriel Jarret, Val Kilmer, and Mark Kamiyama in Real Genius (1985).Sony Pictures Home Entertainment

Michelle Meyrink was a staple of a number of ‘80s comedies, including Revenge of the Nerds. Playing Jordan in Real Genius, she claims to “never sleep” and offers a delightful portrait of high-functioning attention-deficit disorder with a chipper, erratic personality. Disney’s Chip 'n Dale: Rescue Rangers co-creator Tad Stones has confirmed that her character went on to inspire the character of Gadget Hackwrench.

7. A Real Genius subplot, where a computer programmer is gaming a Frito-Lay contest, was based on real events.

In the film, Jon Gries (Napoleon Dynamite) plays Lazlo Hollyfeld, a reclusive genius from before Chris and Mitch’s time who lives in a bunker beneath their dorm creating entries to a contest with no restrictions where he eventually wins more than 30 percent of the prizes. In 1969, students from Caltech tried a similar tactic with Frito-Lay to game the odds. But in 1975, three computer programmers used an IBM to generate 1.2 million entries in a contest for McDonald’s, where they received 20 percent of the prizes (and a lot of complaints from customers) for their effort.

8. One of Real Genius's cast members went on to write another tribute to nerds a decade later.

Dean Devlin, who co-wrote Stargate and Independence Day with Roland Emmerich, plays Milton, another student at Pacific Tech who experiences a memorable meltdown in the rush up to finals.

9. The popcorn gag that ends Real Genius isn’t really possible, but they used real popcorn to simulate it.

At the end of the film, Chris and Mitch build a giant Jiffy Pop pack that the laser unleashes after they redirect its targeting system. The resulting popcorn fills Professor Hathaway’s house as an act of revenge. MythBusters took pains to recreate this gag in a number of ways, but quickly discovered that it wouldn’t work; even at scale, the popcorn just burns in the heat of a laser.

To pull off the scene in the film, Coolidge said that the production had people popping corn for six weeks of filming in order to get enough for the finale. After that, they had to build a house that they could manipulate with hydraulics so that the popcorn would “explode” out of every doorway and window.

10. Real Genius was the first movie to be promoted on the internet.

A week before Real Genius opened, promoters set up a press conference at a computer store in Westwood, California. Coolidge and members of the cast appeared to field questions from press from across the country—connected via CompuServe. Though the experience was evidently marred by technical problems (this was the mid-1980s, after all), the event marked the debut of what became the online roundtable junket.