Is 2024 a leap year? It sure is and this is what it means for your calendar

If you’ve turned the calendar already to take a peek at February, you may have noticed there’s a day you don’t normally see — Feb. 29. That’s because almost every four years, we declare a leap year, adding an extra day in February, or else we risk throwing our sense of time off whack.

This year, 2024, is a leap year. Here’s how it came to be and what it means, especially for those born on the extra day.

What is a leap year?

A leap year is a year that is one day longer than a regular calendar year. This happens almost every four years to ensure the calendar is aligned with Earth’s solar rotation. In 2024, February will have 29 days, rather than 28.

Earth technically takes 365 days, 5 hours, 48 minutes and 56 seconds to orbit the Sun, according to airandspace.si.edu. But the fraction of time left over needs to be accounted for since it amounts to 23.2 hours every four years – almost a whole day, airandspace.si.edu said.

This is why our culture tacks an extra day to the end of February almost every four years.

Without a leap year, months and seasons would occur at different times throughout the year. The summer might begin in March, while winter might occur in June or July, for example.

But technically, 23.2 hours isn’t a full day. If we leap exactly every four years, this would present another problem. We would over-correct, and an extra 44 minutes would be added to our yearly calendar, shifting the months and seasons again, according to airandspace.si.edu.

Scientists have pointed to a common rule to align our calendar year with Earth’s rotation: If the year is divisible by 100, but not divisible by 400, a leap year is skipped, according to airandspace.si.edu.

The year 2000 was a leap year, for example, airandspace.si.edu said. But the years 1700, 1800 and 1900 weren’t. The next time a leap year will be skipped will be the next century, in the year 2100.

What is the history of leap years?

The origin of the leap year can be traced back to 45 B.C., when Roman emperor Julius Ceasar added an extra 24 hours to Feb. 24 every four years, making one long 48-hour day, to align the seasons with the astronomical year, according to leapyearday.com.

But this 48-hour day was not a perfect solution since a year is not 365.25 days long, leapyearday.com said. Eventually, the seasons would be shifted — but not during a lifetime.

By 1582, the misalignment in the Julian calendar would amount to 10 extra days, according to CNN.

To correct this mistake, Pope Gregory XIII made several calculations to eliminate the seasonal shift in the Julian calendar, according to leapyearday.com. Gregory XIII moved the end of the year – which was Feb. 28 – to Dec. 31.

Several days were also “skipped” to make up for the extra leap days that occurred since Caesar’s rule, leapyearday.com said. The pope is also credited for the creation of the common rule scientists use to align our calendar year with the Earth’s rotation.

When will the next leap years be?

According to scienceworld.wolfram.com, the next few leap years will happen in:

What happens if you were born on a leap year?

If you are born on a leap year, it means your birthday falls on Feb. 29. Most “leap babies” or “leaplings” decide for themselves which day to celebrate non-leap years, either Feb. 28 or March 1.

Many also like to joke about their age, since they can either count all of the years they’ve been alive or just the leap years. For instance, someone born on Feb. 29, 2012 can either say they’re turning 12 this year or 3, since there have been three leap years since they were born.

But, legally there is a bit of a challenge regarding how the government counts leap year birthdays. Counting the day someone is born is called the “common law rule,” while not counting the day is called the “birthday rule,” according to a 2016 blog entry by the Executive Office of the Trial Court posted on Massachusetts’ website.

Most sources say the Bay State follows the “birthday rule,” meaning someone born on Feb. 29 would turn a year older on March 1, according to the post. But, there’ve been several cases where the Commonwealth has counted a birthday the day before or the day of someone’s birthday.

“Sadly, we are left unable to clarify the issue for leapers out there,” the blog post concluded.

How does a leap year change the calendar?

Leap years sort of throw off how many otherwise do the easy mental math of figuring out when something will be the following year. If a date fell on a Monday one year, you can usually count on it being on a Tuesday the next year and a Wednesday the year after that. But a leap year throws that off, at least after Feb. 29.

For instance, Christmas was celebrated on a Monday in 2023, but because of the leap day this year, the holiday will be on Wednesday, Dec. 25. If 2024 wasn’t a leap year, Dec. 25 would be on a Tuesday.

Celebrities born on a leap day

Being born on a leap day is incredibly rare. Fewer than 0.07% of human beings will ever be born on Feb. 29, according to thoughtco.com. Even rarer are the chances of becoming a celebrity or famous figure. But believe it or not, there’s a good handful of notable figures who were born on a Feb. 29. Check it out:

Tony Robbins, 63 (or “turning” 16 this year), author and inspirational speakerJa Rule, 47 (or 12 this year), American rapperClark Kent, fictitious journalist and comic book superhero known as “Superman.”Mark Foster, 39 (or 10 this year), lead singer of the band Foster the PeopleJessie Usher, 31 (or 8 this year), the actor known for his role as “A-train” in “The Boys”