YORK, Pa. — This week, we officially recognize that 2024 is a Leap Year by adding an extra day to the month of February.
Here's why we have Leap Years and other fun facts and trivia about the quirky calendar event.
Why We Have Leap Years
To put it in its simplest terms, a Leap Year is when we add an extra day (Feb. 29) to the calendar year ever four years.
According to the Old Farmer's Almanac, adding an extra day to the calendar every four years keeps it correctly aligned with the astronomical seasons.
Why is it necessary? Because centuries ago, people kept track of the sun's position — such as for a solstice or the longest day of the year — to know when to do things like plant and harvest.
The Gregorian calendar used by most of the world since its introduction by Pope Gregory in the 16th century is based on the length of time it takes the Earth to orbit around the sun (365 days).
The problem is that Gregory's math was a little off; it actually takes approximately 365.25 days for the Earth to complete its orbit.
To make up for the extra time, the Gregorian calendar adds a day every four years. So, in 2024, there are actually 366 days on the calendar, not 365.
Without this extra day, our calendars and the seasons would gradually fall out of sync. If we didn't add a leap day every four years, the calendar would be off by 5 hours, 48 minutes, and 45 seconds more each year.
Why we add the extra day in February
OK, so we agree there needs to be an extra day added to the calendar every four years. Why can't we add one to the end of June or some other fair-weather month?
According to NPR, it's because the Romans considered February to be an unlucky month.
Leap Year Rules
It's a bit of an over-simplification to say that leap years occur every four years. There's a little more to it than that.
Here are the rules, according to the Old Farmer's Almanac:
- A year may be a leap year if it is evenly divisible by 4.
- Years divisible by 100 (century years such as 1900 or 2000) cannot be leap years unless they are also divisible by 400. (For this reason, the years 1700, 1800, and 1900 were not leap years, but the years 1600 and 2000 were.)
If a year satisfies both the rules above, it is a leap year.
What if you're born on Leap Day?
The extra day added in February every four years -- Feb. 29 -- is called "leap day."
A “leapling” is a person born on a leap day. Leap Day is the rarest birthday in the Gregorian calendar.
There are about 5 million people worldwide with a Feb. 29 birthday, according to the History Channel. Some famous "leaplings" include rapper Ja Rule and motivational speaker Tony Robbins.
Those who are born on a Leap Day might want to consider playing the lottery sometime; there's only a 1 and 1,461 chance of being born on Feb. 29.
That's why in many cultures, being born on a Leap Day is a sign of good luck.
Are Leap Years Good Luck or Bad Luck?
The Old Farmer's Almanac has found evidence supporting both theories.
Some notable disasters that occurred during leap years include the burning of Rome (AD 64) sinking of the RMS Titanic (1912).
On the other hand, the Pilgrims landed in Plymouth, Massachusetts during a leap year (1620), Benjamin Franklin proved lightning is electricity (1752), and gold was first discovered in California (1848).