What would happen without a Leap Day? More than you might think

NEW YORK — Leap year. It’s a delight for the calendar and math nerds among us. So how did it all start and why?

Take a look at some of the numbers, history, and lore behind the (not quite) every-four-year phenomenon that adds a 29th day to February.

The math is mind-boggling to a layman and down to fractions of days and minutes. Occasionally there’s even a leap second, but there’s no noise when that happens.

The thing to know is that a leap year exists in large part to keep the months in sync with annual events, including equinoxes and solstices, according to the California Institute of Technology’s Jet Propulsion Laboratory.

It is a correction to account for the fact that the Earth’s orbit is not exactly 365 days per year. The journey takes about six hours longer than that, NASA says.

However, contrary to what some may think, every four years is not a leap of faith. According to National Air, adding a leap day every four years would lengthen the calendar by more than 44 minutes & Space Museum.

Later, in a calendar yet to come (we’re getting there), it was decreed that years divisible by 100 do not follow the four-year leap day rule unless they are also divisible by 400, the JPL notes. In the last 500 years there was no leap day in 1700, 1800 and 1900, but there was in 2000. If practice is followed, there will be no leap day in 2100, 2200, 2300 and 2500 for the next 500 years.

Still with us?

The next leap years are 2028, 2032 and 2036.

Ultimately, there is no good when it comes to when major events happen, when farmers plant, and how the seasons correspond with the sun and moon.

“Without leap years, we will have summer in November after a few hundred years,” said Younas Khan, a physics instructor at the University of Alabama at Birmingham. “Christmas will be in the summer. There will be no snow. There will be no Christmas feeling.”

The short answer: it evolved.

Ancient civilizations used the cosmos to plan their lives, and there are calendars dating back to the Bronze Age. They were based on the phases of the moon or sun, as are various calendars today. Usually they were ‘lunisolar’ and used both.

Now move on to the Roman Empire and Julius Caesar. He was experiencing large seasonal deviations in the calendars used in his forest area. They handled drift poorly by adding months. He also navigated a wide range of calendars, starting in a wide variety of ways across the vast Roman Empire.

He introduced his Julian calendar in 46 BCE. It was purely solar and made a year of 365.25 days, so an extra day was added every four years. Previously, the Romans counted a year as 355 days, at least for a certain time.

But under Julius there was still drift. There were too many leap years! The solar year does not last exactly 365.25 days! It’s 365.242 days, says Nick Eakes, an astronomy lecturer at the University of North Carolina’s Morehead Planetarium and Science Center at Chapel Hill.

Thomas Palaima, a professor of classical languages ​​at the University of Texas at Austin, said adding time periods to a year to reflect variations in the lunar and solar cycles was done by the ancients. The Athenian calendar, he said, was used in the fourth, fifth and sixth centuries with twelve lunar months.

That didn’t work for seasonal religious rituals. The drift problem led to the periodic “insertion” of an extra month to readjust to the lunar and solar cycles, Palaima said.

The Julian calendar was 0.0078 days (11 minutes and 14 seconds) longer than the tropical year, so timekeeping errors continued to accumulate gradually, according to NASA. But stability increased, Palaima said.

The Julian calendar was the model used by the Western world for hundreds of years. Then Pope Gregory XIII comes in, who has further calibrated. His Gregorian calendar came into effect in the late 16th century. It is still used and is clearly not perfect, otherwise there would be no need for a leap year. But it was a big improvement, cutting the drift to just a few seconds.

Why did he get in? Well, Easter. It came later in the year, and he was concerned that events associated with Easter, such as Pentecost, might clash with pagan celebrations. The Pope wanted Easter to remain in the spring.

He deleted some extra days that had accumulated on the Julian calendar and adjusted the rules for leap day. It is Pope Gregory and his advisors who came up with the complicated calculation about when there should or should not be a leap year.

“If the solar year were a perfect 365.25, we wouldn’t have to worry about the tricky math involved,” Eakes said.

Oddly enough, Leap Day comes with stories of women putting the question of marriage to men. It was mostly good-natured fun, but it came with a bite that reinforced gender roles.

There is distant European folklore. One story places the idea of ​​women proposing in fifth-century Ireland, with St. Bridget calling on St. Patrick to allow women to propose to men, according to historian Katherine Parkin in an article from 2012 in the Journal of Family History.

No one actually knows where it all started.

In 1904, syndicated columnist Elizabeth Meriwether Gilmer, alias Dorothy Dix, summarized the tradition this way: “Of course people will say… that a woman’s leap year privilege, like most of her liberties, is but a brilliant mockery.”

The pre-Sadie Hawkins tradition, no matter how serious or ironic, could have empowered women but only perpetuated stereotypes. The proposals were supposed to be via a postcard, but many such cards turned the tables and poked fun at women instead.

Advertising perpetuated the leap year wedding game. A 1916 advertisement from the American Industrial Bank and Trust Co. read as follows: “Since it is a leap year day, we recommend every girl to suggest to her father that she open a savings account in her name at our own bank.”

There was no breath of independence for women because of the leap day.

Being born in a leap year on a leap day is certainly a talking point. But from a paperwork perspective, it can be quite tricky. Some governments and others requiring forms to be filled out and birthdays to be noted intervened to specify which date was used by leaplings for things like driver’s licenses, whether it was February 28 or March 1.

Technology has made it much easier for jump babies to write down their February 29 milestones, although problems can arise in healthcare, insurance policies, and other businesses and organizations that don’t have that date built in.

There are approximately 5 million people worldwide who share the leap birthday, out of approximately 8 billion people on this planet. Shelley Dean, 23, in Seattle, Washington, takes a rosy attitude toward a jump. Growing up, she had normal birthday parties every year, but an extra special one when leap years came around. Because as an adult, she marks that non-leap period between February 28 and March 1 with a quiet “whew.”

This year is different.

“It will be the first birthday I’ll celebrate with my family in eight years, which is super exciting because the last leap day I was on the other side of the country in New York studying,” she said. “It is a very important year.”