Why we have leap years

Invented over 2,000 years ago, leap years are a necessary need for the internationally used Georgian calendar. Without it, seasons would be traditionally indistinguishable.

2020 is special because it’s a leap year and possesses an extra day. Occurring almost every four years, Feb. 29 is recognized as a leap day and possesses a more complicated backstory than one might think.

Leap days keep the Gregorian calendar aligned with Earth’s revolutions around the Sun, which takes approximately 365.242189 days, or 365 days, 5 hours, 48 minutes, and 45 seconds and that number continually shrinks on a minuscule scale with each passing year. This is recognized as a tropical year and it starts on the March equinox.

The Gregorian calendar only possesses 365 days and replaced its predecessor, the Julian calendar nearly 1,500 years ago. If we didn’t add a leap day on Feb. 29 almost every four years, each calendar year would begin about 6 hours before the Earth completes its revolution around the Sun.


 Winter 2019-2020

Winter 2019-2020

Start (December Solstice)
Dec. 21, 2019 11:19 pm
Duration 88 days, 23 hours, 30 minutes
 Spring 2020

Spring 2020

Start (March Equinox)
Mar. 19 11:49 pm
Duration 92 days, 17 hours, 54 minutes
 Summer 2020

Summer 2020

Start (June Solstice)
Jun. 20 5:43 pm
Duration 93 days, 15 hours, 46 minutes
 Autumn 2020

Autumn 2020

Start (September Equinox)
Sep. 22 9:30 am

Duration 89 days, 20 hours, 31 minutes


Without our leap years, our understanding of time and recognition of traditional seasons would drift out of sync. With a deviation of approximately 6 hours per year, the seasons would shift by about 24 calendar days within 100 years. If this were allowed to happen those who reside within the Northern Hemisphere would be celebrating Christmas in the middle of summer after the course of a few centuries.

According to timeanddate.com, leap days fix that error by giving Earth the additional time it needs to complete a full circle around the Sun.

Forecasting leap years

In order to be identifiable as a leap year, the year must pass a series of necessary criteria.

  • The year must be evenly divisible by four.
  • The year must be divisible by 400
    • If the year can also be divisible by 100, it is not a leap year
Screen Shot 2020-02-28 at 7.13.22 PM
Graphic by Daily Planet

If leap years were never created the weather and overall recognition of the climate would remain the same, but the month and year would be starkly different.


Coincidently, in DC Comic’s continuity, Superman’s birthday falls on the leap day of every leap year, but that’s a story for tomorrow. Unmarked graphics are courtesy timeanddate.com

 

 

Zack Benz

Zack Benz has been a fan of the Daily Planet since he was eight years old. The Daily Planet has always been a beacon of hope for him and it’s his life’s mission to make it shine in a similar light to so many around the world. Zack graduated with a degree in journalism and art from the University of Minnesota Duluth in 2019.

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