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Leap year (symbolic image).
© Bihlmayerfotografie/Imago
Every four years February gets a leap day, but why?
Otherwise the entire calendar would shift over the years.
Without leap years, the Fourth of July would be sometime in winter.
The leap days, added to the end of February every four years, keep our calendars in sync with Earth's orbit, says Shauna Edson, an astronomy educator at the National Air and Space Museum.
Our standard calendar year has 365 days - but Earth actually takes 365,256 days to orbit the sun, she said.
If you add February 29th to the calendar every four years, you make up for that quarter day.
Without this addition, our calendars would be one day ahead of Earth's orbit every four years, which works out to 24 days per century, Edson said.
This means that our seasons and solstices would slowly but surely occur at very different times than we are used to.
“We might not notice it at first,” Edson said.
“But at some point we would celebrate the Fourth of July and it would snow.
Halloween would no longer be a fall festival and Easter would no longer take place in spring.
And it would take centuries for the seasons to return to what we expect.
“The way we humans measure time doesn’t exactly match the orbit around the sun,” Edson said.
“We like things to be presented in nice, clean numbers.
Nature doesn’t really work that way.”
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Are leap years the solution?
Not everyone believes that
Not everyone believes that adding an extra day every fourth of February is the solution.
In 2020, two scientists proposed abolishing leap years and creating a new annual schedule: one that is 364 days long, with the year always starting on a Monday and most months being 30 days long.
Instead of leap years, scientists suggested adding an additional week to the calendar every five or six years “in which to celebrate.”
(That didn `t work.)
As the
Washington Post
reports, managing our man-made calendar is a practice dating back thousands of years, with variations spanning the globe.
Drawing inspiration from the Egyptian solar calendar, which included 365 days and occasionally an additional month, Julius Caesar reorganized the Roman calendar to include 365 days and add a day to the second month of the year every four years, the Post
reports
.
This calendar appeared around 46 BC.
In force.
However, there were some discrepancies.
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Since Earth's orbit around the sun is not exactly 365.25 days, but rather about 365.25 days, adding an extra day every four years still isn't quite right, Edson said.
This was a particular concern for the Catholic Church in the 1500s,
The Post
reported.
Gregorian calendar excludes leap days in years with two zeros
The date of Easter had strayed too far from its traditional time, so Pope Gregory XIII.
commissioned a calendar in the 1580s that excluded the addition of leap days in centennial years - years ending with two zeros - unless the centennial year is divisible by 400.
This means that the years 1700, 1800 and 1900 were not leap years, but the year 2000 was.
Before the year 2000, the last centennial leap year was the year 1600, Edson said.
This adjustment brings the modern Gregorian calendar into close alignment with Earth's actual orbit around the sun - although it does make leap years a little strange to track.
For Americans, there's usually a simple trick to knowing when a leap year is, Edson added.
“Leap years coincide with presidential election years.
Maybe that's why the campaign season feels so long.
About the author
Anumita Kaur
works as a reporter for The Washington Post, where she covers breaking news and writes stories that affect the moment.
She previously reported for the Los Angeles Times and the Guam Pacific Daily News.
We are currently testing machine translations. This article was automatically translated from English into German.
This article was first published in English on February 27, 2024 at the “Washingtonpost.com” - as part of a cooperation, it is now also available in translation to readers of the IPPEN.MEDIA portals.