HOLT, Fla., Feb. 29, 2024—There’s an extra day in the calendar this year.

Almost every four years, an extra day is added to the end of February. This is done to ensure the calendar is in sync with the Earth’s travel around the sun.

It takes the Earth 365.2422 days to orbit the sun (356 days, 5 hours, 48 minutes and 56 seconds to be exact). That .2422 equals about 1/4 of a day, which adds up to 24 hours every four years.

To make matters more fuzzy, leap days are added to centurial years—turn-of-the-century years such as 1900—divisible by 400, unless they’re not divisible 400, in which case, the leap day is skipped.

Huh?

Simply put, the years 1700, 1800 and 1900 were not leap years, but 2000 was because it is divisible by 400.  That means 2100 will NOT be a leap year because it’s not divisible by 400.

Why Leap Days?

So who thought up this “higher” calendar math?

The idea of adding extra days to the calendar began centuries ago among ancient populations such as the Hebrews, Chinese and Buddhists. Roman emperor Julius Caesar, borrowing the idea from the Egyptians, began adding a day every year to his calendar (known as the Julian Calendar) on Jan. 1, 45 B.C. However, that began shifting important days associated with the solar equinox further and further away.

Pope Gregory XIII corrected this in the 16th century by creating the Gregorian Calendar (the one in use today). He added leap days in years divisible by four, as discussed above. This kept the dates in line with the seasons. For instance, (get ready for more calendar math…) Easter falls on the first Sunday after the first full moon following the vernal equinox (aka, first day of spring).

If there was no Leap Day, in the northern hemisphere, by the year 2777, the calendar would show winter during the hot months and summer during the cold months.

Did you know…

More than five million people worldwide were born on Feb. 29, according to information by the History Channel.

The odds of being born on Leap Day are 1 in 1,461 (356.25 times 4—more math).

Those born on Feb. 29 are known as “leaplings” or “leapers.” Some celebrate their birthdays on Feb. 28 or March 1 each year. Some even keep the celebration going for the whole week.

Anthony, Texas, and its partner city, Anthony, New Mexico, are the self-proclaimed Leap Year Capital of the World. They celebrate Leap Day with celebrations and parades.

There’s even an honor society for Leap Year babies.

In Greece, however, it’s considered bad luck to get married on Feb. 29 and the Romans considered February to be an unlucky month.

Regardless of whether you were born on a day that only shows up every four years, or if you’re superstitious about the month of February, enjoy the extra day.