Breakdown: Why we have a leap year (2024)

FAQs

Breakdown: Why we have a leap year? ›

The necessity for leap years arises from the fact that Earth's orbit around the Sun takes approximately 365.2425 days. To accommodate this slight discrepancy, we add an extra day every four years to keep our calendar aligned with the astronomical year.

The necessity for leap years arises from the fact that Earth's orbit around the Sun takes approximately 365.2425 days. To accommodate this slight discrepancy, we add an extra day every four years to keep our calendar aligned with the astronomical year.

It makes sense that such a jam-packed year should get an extra day. The simple explanation for why we have leap days is that it takes 365.2422 days for our planet to complete one revolution around the sun. That means each typical 365-day year ends a quarter day's worth short of the complete orbit.

A leap year (also known as an intercalary year or bissextile year) is a calendar year that contains an additional day (or, in the case of a lunisolar calendar, a month) compared to a common year. The 366th day (or 13th month) is added to keep the calendar year synchronised with the astronomical year or seasonal year.

But it actually takes Earth 365.242190 days to orbit the sun, says Jackie Faherty, an astronomer at the American Museum of Natural History in New York. "And that . 242190 days to go around the sun is the entire reason why we have a leap year," she explained.

This means that when the Roman calendar added an extra day in February, they were in fact adding a day at the end of their year. So the simple answer is that we put the leap day at the end of February because the Romans did.

When it comes to legal documents, such as obtaining a passport or driver's license, the date February 29th is recognized as the official birthday for leaplings in most countries. However, some states in the U.S. allow the leapling to celebrate their birthday on either February 28th or March 1st on non-leap years.

In the Gregorian calendar, a normal year consists of 365 days. Because the actual length of a sidereal year (the time required for the Earth to revolve once about the Sun) is actually 365.2425 days, a "leap year" of 366 days is used once every four years to eliminate the error caused by three normal (but short) years.

Who decided we needed a leap year? ›

To fix his culture's calendar, Roman emperor Julius Caesar created the Year of Confusion when he decided that the year 46 B.C. was going to be 445 days long instead of 365 days long. He then made a 365.25-day year—a tiny bit longer than the 365.2422 solar year—that added a leap day every fourth year.

Yes, 2024 is a leap year. For the first time since 2020, we have an extra day in February. This year, Leap Day falls on Thursday, February 29, 2024. The next time the shortest month of the year will get an extra day will be in 2028, so make sure to savor the extra day while we've got it!

2024, 2028, 2032 and 2036 are all leap years.

To check if a year is a leap year, divide the year by 4. If it is fully divisible by 4, it is a leap year. For example, the year 2016 is divisible 4, so it is a leap year, whereas, 2015 is not. However, Century years like 300, 700, 1900, 2000 need to be divided by 400 to check whether they are leap years or not.

A Leap Century Year is one that is easily divisible by 400. If it divisible by 4 but not divisible by 400 then it never considers a Leap Century Year. Here, 800, 1600 and 2000 easily divisible by 400. So, These are Leap Century Year.

The Gregorian calendar omits three leap days every 400 years which is the length of its leap cycle. This is done by omitting February 29 in the three century years (multiples of 100) that are not multiples of 400. The graphic below paints a good picture as to why we have them and what would it do if we didn't.