Leap day and leap year: Everything you need to know

Do you know why you get an extra 24 hours this year? 2024 is a leap year. Want to know why we get this bonus day, AKA leap day? TAG24 has you covered.

Here's everything you need to know about leap years like 2024!
Here's everything you need to know about leap years like 2024!  © Collage: 123rf/potjanun & 123rf/bbbrrn

Calendars and time are tricky business.

A year is defined by the amount of time it takes a planet to go around its sun once. A day, on the other hand, is the amount of time it takes our planet to rotate on its own axis.

We tend to think that a year has exactly 356 days, but that's not the whole truth.

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It actually takes our blue planet a tad more than 365 days to orbit the Sun – at 365.242190 days. To make up for this missing bit of time, we add one day or our calendars approximately every four years, and voilà, you have a leap year!

A leap year like 2024 has 366 days, with an extra leap day on February 29.

While a leap year may seem silly, it's vital for keeping our calendars in line.

Why do we have leap years?

Leap years ensure consistency with the astronomical year by making up for lost time, allowing our seasons to remain in sync.
Leap years ensure consistency with the astronomical year by making up for lost time, allowing our seasons to remain in sync.  © 123RF/liudmilachernetska

Leap years keep our seasons from drifting.

By adding a day nearly every four years, we keep our human calendar in line with the Earth's movement around the sun.

If we didn't have leap years, the extra hours would add up over time, and our calendar and the seasons would no longer be in sync.

You'd end up with a July full of snow in the Northern Hemisphere!

In other words, leap years ensure consistency with the astronomical year by making up for lost time.

How often do leap years occur?

We still use the Gregorian Calendar today.
We still use the Gregorian Calendar today.  © 123RF/ra2studio

Julius Caesar introduced leap years in 45BCE with an edict and kept things simple. He wanted a bonus day every four years, and decided to add it to the shortest roman month, February.

The only issue was Caesar's math didn't quite add up.

As a year is actually 365.242190 days, adding an extra day every four years ends up making the calendar longer by 44 minutes. Caesar's rounding up actually ended up creating a problem.

Scholars in the 16th century noticed that time was still out of joint, and the Catholic Church wasn't happy about the traditional date of Easter drifting. That's why Pope Gregory XIII commissioned a calendar modification of the Gregorian Calendar, which we still follow today.

Long story short: leap years occur nearly every four years, but only approximately, or things would still be wonky.

"The rule," per the National Air and Space Museum's website, "is that if the year is divisible by 100 and not divisible by 400, leap year is skipped. The year 2000 was a leap year, for example, but the years 1700, 1800, and 1900 were not. The next time a leap year will be skipped is the year 2100."

This year 2024 is a leap year and so are 2028, 2036, 2040, and so on.

Leap years may be the result of calendar calculations meant to keep our seasons from drifting, but they are also special for other reasons. After all, there's only a February 29 every four years!

What do you call someone born on a leap day?

As leap years only happen around once every four years, having a birthday on February 29 is pretty special. In fact, it's the rarest birthday of them all.

There are only about 5 million people in the whole world born on a leap day! Those born on this special day are called "leapers," leaplings," or leap day babies. It's a pretty elite group that even includes hip hop artist Ja Rule.

The real question is: what are you going to do with your extra 24 hours this year?

Cover photo: Collage: 123rf/potjanun & 123rf/bbbrrn

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