How We Can Trace the History of Leap Year Back to a Pope
“Creation proclaims the glory of God” (USCCB, citing Daniel 3:56-82).
This year is a leap year, and articles about it abound, with topics such as how people born on February 29 celebrate their birthday (only every four years, on February 28, or on March 1) or if leap years are even necessary. I’m unable to attest to the former, yet the latter yields many stories to bring to your next standup meeting or networking fun fact.
The History of Leap Year Is Catholic
Some say we’re due for a reevaluation of the leap year system in about 3,300 years, and some say within the next 8,000 years. Either way, we need leap years for at least the next few millennia so that our seasons don’t go off track. Most beautifully, the implementation of the leap year goes back to Pope Gregory XIII.
Earth’s orbit around the sun (a seasonal year) is not a whole number; scientists currently approximate a solar year to 365.2422 days. Sosigenes, Julius Caesar’s astronomer(47-45 BC) established a rudimentary calendar that first introduced leap years to Western civilizations, truncating the solar year to 365.25 days. This Julian calendar was used for more than seven centuries, but it had major inaccuracies.
St. Bede, an English monk, noticed that Sosigenes’ calculation was 11 minutes and 14 seconds too long to keep in time with Earth’s orbit around the sun. Unfortunately, his calculations were not recognized at the time, since they added up to an error of only 24 hours every 128 years. However, as centuries continued, these errors compounded, and by the 16th century, the calendar was really wonky!
In 1582, the calendar fell out of sync with the sun, and Pope Gregory XIII noticed that the spring equinox landed on March 11 rather than March 21. He removed 10 days from October, and that year, the calendar went from October 4, 1582 to October 15, 1582. (Think of the many birthdays that were missed that year—or, the confusion that ensued for harvest season!)
Pope Gregory appointed Jesuit missionary and mathematician Christopher Clavius to do the calculations that would last for several millennia by taking into account that the Earth revolved around the sun every 365.2422 days.
Faith and Reason
Our Catholic faith is rich with history that shows its time-tested grounding in both faith and reason. The leap year is one clear example! So, why are we sometimes reluctant to integrate our rich faith heritage into STEM fields? Why must we keep science to reason alone, when we have clear evidence of how faith inspires reason? By integrating our faith into our work, we apply St. Augustine of Hippo’s analogy of mind: The image of God is fully alive in us when our intellect, memory, and will are ordered to our Triune God! This, in turn benefits others, because we can offer up our interactions for God to pour out His grace grace on them.
Science answers the “what” and the “how,” and faith answers the “who” and the “why.”
For me, the story of leap years demonstrates God’s care that proceeds from the Spirit. We are, after all, His children, who are the body of His one church. Guided by the Holy Spirit, we are given the inspiration we need to always get back on track.
St. Bede, pray for us!
Elisejane Plecnik is an Indiana-based Catholic who is a creative technologist specializing in software development. Outside of code, she contemplates Jesus through Mary. Inside code, she contemplates Jesus through Mary. She hopes to share all things theology and code which keep all members of CWIB resplendent and flourishing. Connect with her on LinkedIn.