leap day circled on calendar
Why do we have leap day in February? And how are the Catholic Church and Easter involved?

This year, we'll have a February 29th: an elusive 366th "leap day" that comes ‘round every four years to balance the calendar year with the rotation of the earth around the sun.

Years containing this additional day are called leap years – and 2024 is one of those special years!

But… Why February 29th? And did you know the Catholic Church has a part to play in the answer?

This is the secret religious history of leap day.

Today is Leap Day! This peculiar extra day appears every four years to help align our calendar with the Earth's orbit...

Posted by Universal Life Church Ministries on Thursday, February 29, 2024

Making Up For Lost Time

It takes the earth approximately 365.25 days to fully orbit the sun, meaning that if we didn’t account for this somewhere, over time entire seasons would shift due to the subtraction of six hours every year. 

Over any individual’s lifetime, things wouldn’t shift dramatically. But over centuries, entire seasons would shift entirely. 

Astronomers originally discovered this astrological oddity thousands of years ago, and proposed leap days (or leap months) to make up for the lost time.

Many ancient cultures (and some modern ones) used a lunar calendar, necessitating regular additions of an entire 13th lunar month. The Hebrew calendar, for example, added an extra month seven times every 19 years, and the original Roman calendar was 355 days, with an additional 22 or 23 day month every two years.

Origins of Leap Year

Leap years, as we know them today, go back to the time of Julius Caesar, who added another day to the Roman calendar every 4 years to balance the solar books.

Taking inspiration from the solar calendar of Egypt, and under the guidance of a cohort of Greek astronomers, in January 46 BCE, Julius Caesar standardized the Roman calendar, simplifying it to 365 days, with an additional leap day every four years. This became the standard calendar for much of the western world for generations.

Things stayed relatively the same for some 15 centuries, until Pope Gregory XIII was made aware of a little problem: Easter, the Christian holiday celebrating the resurrection of Jesus Christ, was drifting further and further from the spring equinox. Left unchecked, the holiday would careen away from the spring season, like Easter eggs tumbling down a cliff.

Related post: The Real History of Easter: a Pagan Holiday

But how did the Church discover this problem? And what could they do to fix it?

Saving Easter Sunday

The timing of Easter was formally set by the Council of Nicea in 325 as the first Sunday following the first full moon after the spring equinox.

The Julian calendar was designed so that the spring equinox landed on March 21st (or thereabouts). But over the previous 1,500 years, Easter had drifted about ten days away from the spring equinox. How did that happen?

The answer boils down to some complicated math: it actually takes the earth 365.242222 days to orbit the sun, not 365.25. In other words, a leap day every fourth year is actually too many leap years. 

So, Pope Gregory XIII set about developing what came to be known as the Gregorian calendar, adding another day to February on years that are multiples of four – unless the year is evenly divisible by 100, but not by 400.

Problem solved! Holidays are now firmly affixed to their seasons, Easter is safe and sound near the spring equinox where it belongs, and the Gregorian Calendar eventually became the calendar most widely used in the world today.

However, it is not perfect – this new and improved version is still off by one day every 3,236 years. 

But hey, that sounds like a problem for future civilizations.


  1. Joy's Avatar Joy

    Oh I am so glad the Pope was there to fix something that didn't really need a whole lotta fixing just to appease his eggs.

    1. Takaya Kovani Sweeney's Avatar Takaya Kovani Sweeney


  1. Kevin Oconnell's Avatar Kevin Oconnell

    Good story to tell but doesn't affect my breathing.

  1. Russel A. Kester's Avatar Russel A. Kester

    How very interesting. Thank you. One can just imagine how different society can be based on how we tell time and the cycle of the year. I doubt pagan societies that used the sun and moon got to confused, but become "civilized" by using a calendar and look at the challenges! 😊

  1. John Condron's Avatar John Condron

    Umm... there is nothing "secret" about this. I learned this bit of history in fifth grade.

  1. Robert Enge's Avatar Robert Enge

    but is the pope a man of is word he not god is the only person i believe in and trust with my life and my wife

  1. Rev. Klaire ThD, MA's Avatar Rev. Klaire ThD, MA

    Not secret or nefarious but the interesting thing to ponder is that without February 29th every four years, the seasons would be off by one entire season every 120 years!

  1. Takaya Kovani Sweeney's Avatar Takaya Kovani Sweeney

    Soooo, yada yada yada…time isn’t real and everyone has fd with it so no one except the Hebrews even have an INKLING of what year/time we’re ACTUALLY in.

    Okay, thanks for the recap.

  1. Theresa C. Marquess's Avatar Theresa C. Marquess

    In elementary school, we learned the hows and whys of Leap Year. The Gregorian Calendar works for me!

  1. Estrella Ruth Rojas's Avatar Estrella Ruth Rojas

    So every four years was too much but we have a leap year every four years….

  1. David Richard Mumma's Avatar David Richard Mumma

    Let's update your history book. In Old Testament times, the earth had a 360 day year. In that time period the orbits of planet earth and mars were resonate, passing closely by each other every 120 years. In 701 BC that pass by was so close that their orbits were changed, so earth lost energy and its orbit now has a 365.24+ year. It also changed mar's orbit so there were no longer any close incidents.

  1. Brooke Rogers's Avatar Brooke Rogers

    I absolutely love this newsletter!

  1. Amanda Qualls's Avatar Amanda Qualls

    It's all about the numbers

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