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Two of the years burned into our collective memory happened to be leap years: 2016 and 2020. Well, in case you haven’t yet heard, 2024 has something big going for it aside from the upcoming elections: It’s getting a bonus day, too.
This February has 29 days instead of the standard 28, meaning that you can have an entire extra day to try to find a cure for cancer or train for an upcoming marathon – or maybe just binge-watch reality TV. You do you, boo.
Out in West Texas, you’ll find the Leap Year Capital of the World. The small town of Anthony in El Paso County earned its title thanks to a resident who wanted to honor those born on Feb. 29, such as her friend and neighbor Bettie Luis, according to the city’s website.
What Is Leap Year?
Leap day is a pretty simple concept, noted Ohad Shemmer, an astronomer and associate professor in the College of Science at the University of North Texas. During leap years, the month of February gets an extra day added to it. Boom.
It’s like if there were four apples handed out to three people, he said. One day, Peter would receive two apples and the next day, the extra “leap apple” would go to John.
However, leap years get more complicated upon closer examination. The number of days that it takes the Earth to revolve around the sun isn’t whole and round. Rather than being exactly 365 days, Shemmer said, the globe’s journey takes around 365.2422 days or so.
“So what do we do? We can say, ‘Let’s ignore it: just do 365 and see what happens,'” he said. “What’s going to happen is, after a few years, you’re going to start seeing the summer in November, and then the winter in May and all sorts of funny things are going to happen. It’s not going to be aligned with the seasons.”
“Here’s obviously all these political things that are happening today. And what did they trace back to? They trace back to the fact that we have leap years.” – Dr. Marc Hairston, UT Dallas
When Do Leap Years Happen?
Leap years occur once every four years, which is why we also enjoyed a Feb. 29 in 2020, 2016, 2012, 2008 and 2004, to name a few examples. They’re skipped over if the year in question can be divided equally by 100, Shemmer said – except for years that can be divided equally by 400.
This is why 2000, which is divisible by both 100 and 400, was a leap year – and why the same won’t be true for the year 2100, which is divisible by 100 but not 400.
A (Brief) History of Leap Year
The original Roman calendar was just 10 months long, said Marc Hairston, a research scientist in the William B. Hanson Center for Space Sciences at the University of Texas at Dallas, where he also teaches astronomy. That explains, for instance, why September is derived from the Latin term for “seven,” despite being the ninth month.
Eventually, the Julian calendar, named after Julius Caesar, would install a 365-day year with a leap day every fourth year, he said. But there was an issue with this, too: After 128 years, it would get one day out of sync.
Hairston explained that in 1582, a new calendar named after Pope Gregory reset the whole system: “What did the Gregorian calendar do different? Well, basically they said, ‘Look, we’ve got too many leap years.'” And that’s why we now take the additional “divisible by 400” step when looking at century years.
The Gregorian calendar will be A-OK for another couple of thousand years, Hairston added: until around 4800.
Leap Year’s Ties to Ukraine and Russia
Another significant day is happening later this month: the two-year anniversary of Russia’s invasion of Ukraine.
Russia was late to adopt the Gregorian calendar, Hairston said. Still, the Russian Orthodox Church decided to stick with the Julian calendar, which had been used back in biblical times.
Last year, the Ukrainian church broke from its Russian Orthodox counterparts by switching its Christmas to the Gregorian calendar. Russia celebrated Jesus’ birth on Jan. 7 this season, he said, but Ukraine joined the Western world and rang in the holiday on Dec. 25.
“So, here’s all these political things that are happening today,” Hairston said. “And what did they trace back to? They trace back to the fact that we have leap years. And the fact that Julius Caesar set up this calendar that wasn’t quite right back in 46 BC.”
