Every four years, the calendar makes room for an extra day, creating what is known as a leap year – a phenomenon that is intriguing, puzzling, and practical. Today, at the end of February, the world is celebrating this unique occurrence, which adds a touch of novelty and an extra 24 hours to our usual month.

Leap years, marked by the addition of an extra day to the month of February, are necessary to keep our calendar in sync with the Earth’s revolutions around the sun. While a year is traditionally defined as 365 days, it actually takes approximately 365.24 days for the Earth to complete its orbit. Without the adjustment provided by leap years, our calendar would gradually fall out of alignment with the seasons.

According to Alexander Boxer on NPR, “it’s an ‘awkward calendar hack’ aimed at making up for the fact that a year isn’t a flat number of days, but more like 365 and a quarter. But there’s more to it than that […] I think the significance of the leap year is that it’s a great reminder that the universe is really good at defying our attempts to devise nice and pretty and aesthetically pleasing systems to fit it in.”

“This extra day ensures that our calendar stays accurate over time,” explains Boxer. “By adding a leap day every four years, we compensate for the slight discrepancy between the calendar year and the astronomical year, keeping our seasons in sync with the natural cycles of the Earth.”

The tradition of leap years date back to ancient times, with the ancient Egyptians being among the first to develop a calendar based on the solar year. Julius Caesar borrowed the idea of leap year from Egypt, though it had been around longer than that in many other cultures.

It was Caesar who introduced the leap year system as part of the Julian calendar reform in 45 BCE. This calendar, which included a leap day every four years, served as the basis for the modern Gregorian calendar that we use today.

Unfortunately, “Caesar overestimated the solar year by about 11 minutes, leading to an overcorrection by about eight days each millennium. That explains why Easter, for example, fell further and further away from the spring equinox over time,” according to NPR.

Though most people probably don’t think too much about leap year, there are a few things that really stand out. For one thing, the month of February is the shortest month in the year, and even though it doesn’t give away that title even once every four years, it does bulk the month up edging it much closer to 30. 

Next, we may consider the way it moves the calendar the entire year, pushing every day one day ahead. If your birthday was on a Saturday last year, bad news – it’ll be on a Monday this year. 

Speaking of birthdays, Leap Day birthdays are here at last! If you were born on Feb. 29, congratulations you are one of the approximately 5 million people who get this same birthday once every four years. Also, a very happy birthday to you!

Some believe that babies born on Feb. 29, known as “leaplings” or “leapers,” possess special talents or luck. The big rip-off is that leapers only get to truly celebrate their birthday every four years, typically having to choose to celebrate it a day early, on Feb. 28, or a day late, on March 1.

Leap years have also given rise to various customs and traditions around the world. In many cultures, leap day is considered a time for unconventional activities, such as women proposing marriage to men – a tradition that dates back to the fifth century in Ireland when St. Bridget supposedly struck a deal with St. Patrick to allow women to propose on this special day.

Leap year proposals have become a fun and lighthearted tradition for many couples. It’s a chance to break free from traditional gender roles and embrace spontaneity and romance. Others consider Leap Day to be a time for taking risks and making bold decisions, symbolizing the leap into the unknown.

Whether through birthdays, celebrations, proposals, or simply enjoying the rarity of the occasion, Leap Day serves as a reminder of the traditions and customs that connect us across cultures. It is also a testament to the great lengths we have taken to bring order to the chaos of the universe, and the ways in which we have to adapt to allow us to mark and track the passage of time with something as seemingly simple as a calendar.

 So, whether you’re a leapling happy to celebrate your fourth birthday at age 16, your fifth at 20 (or any other multiple of four), or you’re just curious about what Leap Year is or why it happens, do something a little special today – afterall, it’s the rarest day in the calendar.