LOS ALAMITOS, CA – Approximately every four years, there is an extra day added to the calendar year that seems to have no large impact on people’s daily lives. However, the science behind why leap years exist explains a lot of natural phenomenons that occur worldwide. 

Why do leap years exist? 

Leap years exist because a planet’s orbit around the sun is not perfectly in line with the rotation on its axis. Scientifically speaking, a year is the amount of time it takes a planet to orbit its star one time, and a day is the amount of time it takes a planet to finish one rotation on its axis. This cycle is what keeps the days in a year in balance, and leap years continue to help with maintaining that balance. 

“Leap years [keep] the calendar in sync. If leap years did not exist, the middle of summer would become the middle of winter,” said astronomy expert and scientist, Dr. Stephen Hughes, during an interview with the American Institute of Physics.

According to NASA, it takes Earth approximately 365 days and six hours to orbit the sun, while it takes Earth approximately 24 hours to rotate on its axis. Our year is not an exact number of days, and because of that, most years we round the days in a year down to 365 to be in line with the standard Gregorian calendar. 

However, that leftover piece of a day doesn’t disappear. To make sure we count that extra part of a day, we add one day to the calendar approximately every four years. Because we’ve subtracted approximately six hours — or one quarter of a day — from 2021, 2022 and 2023, we have to make up that time in 2024. 

“In other words, the calendar is out of sync by about one day out every four years,” Hughes said. 

Leap years do not occur every four years 

Because of the fact that the Gregorian calendar does not account for the extra part of the day that the Earth requires to complete its orbit around the sun, it doesn’t completely match with the solar year. We account for the extra time that is added to our calendar during leap year, which leads into why the beginning and end of seasons shift year to year. 

“Because the extra time required for the sun to get back to the same position is just short of one quarter of a day, three Leap Days are missed out every 400 years,” Hughes said during an interview with the American Institute of Physics.

There are two typical rules that allow a year to be a leap year, according to the Smithsonian. The first rule is that a year may be a leap year if it is evenly divisible by four. The second rule is that years divisible by 100, such as century years 1900 or 2000, cannot be leap years unless they are also divisible by 400. This is the main reason why the years 1700, 1800, and 1900 were not leap years, but the years 1600 and 2000 were. 

While these two rules make it easier to predict a leap year’s occurrence, most people do not realize it is a leap year until they see Feb. 29 lighting up their phone screen. 

“I didn’t realize that we haven’t had [a leap year] in a while. Maybe it’s good? It could be a new beginning,” Nina Lynes, senior, said. 

Leap year “babies” 

The idea of celebrating your birthday on a day other than your actual birthday is unappealing to most people, but for those born on Leap Day, it is just another attribute that makes them unique. The weird part is that leaplings, those born on Leap Day, are technically only babies.

“My aunt was actually born on Leap Day. It’s weird to think that she’s technically seven or nine,” Lynes said. 

 For sophomore Abi Seidenberg, who currently majors in journalism at Northern Arizona University in Flagstaff, Arizona, having her birthday on Leap Day is a major benefit. 

“It’s actually kind of awesome being born on Leap Day… you can win so many bets when people can’t guess your birthday, and it’s something unique about myself,” Seidenberg said. 

Seidenberg, who will be turning five this year in leap years, explained that it depends on the year how she celebrates her birthday. Typically, she likes to celebrate with something small in non-leap years and makes sure to plan big in a leap year. 

“Normally, I don’t really throw a party unless its a leap year (with a few exceptions, like my 18th birthday, since that’s a big milestone),” Seidenberg said. “On non-leap years, sometimes I’ll just have a nice dinner and a movie or something! On leap years, we go all out.”

Seidenberg explained that despite the fact that her birthday only appears on a calendar approximately every four years, there is no legal difference between her birthday and any other birthday. All legal documents have her actual birthday, but she isn’t sure how this will change when she turns 21. 

“I’m not sure it will make a difference when people check my ID,” she said. “The only thing that might change is I won’t be able to have a drink on my birthday since I’m not going to have a 21st birthday until 2088, but I should be all set on March 1 of 2025!”

For leaplings, it is common for them to hear the “you are turning four years old” joke very often. Seidenberg, who hears this joke in various forms, is typically the one who makes these jokes and shoves it in everyone’s face.

“Lots of people will say, ‘You’re the smartest/tallest/oldest four -year-old I know’ or something like that. It’s pretty funny the first, second, sometimes even third time,” she said. 

Leap year fun facts 

The peculiarity surrounding leap years and their unusual occurrences have also provided interesting twists to the courses of events and traditions in history. Listed below are some fun facts that are unknown to most people about Leap Days.

1. Leap year proposals

According to an Irish tradition dating back to the fifth century, Feb. 29 is traditionally the day when women can put aside tradition and propose to a man. This custom has been credited to historical figures such as St. Bridget, who is rumored to have complained to St. Patrick that women had to wait too long for their suitor to pop the question. Patrick, who obliged to this suggestion, supposedly gave women a “concrete” day to propose.

2. There is a leap year capital!

On Feb. 29 for leaplings only, there is a four-day festival called the Leap Day Festival held in the twin cities of Anthony, Texas and Anthony, New Mexico in the self-proclaimed “Leap Year Capital of the World.” This festival is a huge birthday celebration for leaplings that requires an ID for entry and plenty of fun festivities. 

3. There is a Leap Day Club

The Honor Society of Leap Year Day Babies is a club for those born on Feb. 29, according to Leap Year Day. This club was started in 1997 when two Leap Day birthday clubs, the Leap Year Honor Society and Leap Year Babies Limited, merged to become a proud society of leaplings. One of their main goals is to promote Leap Year Day Awareness (LYDA) and over 11,000 people all over the world have joined over the years. Because of the rise of the internet and social media, they are a smaller club as of right now. 

These fun facts are a few among the many celebrations seen throughout the world every leap year. While it is easy to forget a leap year, it is not everyday that Feb. 29 is on the calendar, so make sure to take advantage of the moment!