Why Is October Missing 10 Days in the Year 1582? — Here’s What Historians Discovered

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Imagine sleeping in one day of the calendar only to wake up 10 days after it. That’s exactly what happened in different parts of Europe in the year 1582. There were literally no people who were recorded to be born on those missing days, and no significant events were officially written.

However, this strange jump from October 4, 1582, to October 15, 1582 was not a mistake. It was purposely done to fix a problem that has been growing for nearly a thousand years. This may seem like it was not a big issue, but the errors it would result in could compile over time to be a much larger trouble.

The Problem with the Old Julian Calendar

How 10 Days Were Deleted… Literally! | Obscure Curiosities
How 10 Days Were Deleted… Literally! | Obscure Curiosities

Before 1582, most European countries were using the Julian Calendar set by Julius Caesar in 46 B.C.E. At first glance, it would sound simple and right, as it follows a year that has 365.25 days, with a leap day being added to the calendar every 4 years. However, the real length of the year is about 365.2422 days.

In other words, every year, the calendar is being pushed slowly by about 11 minutes and 14 seconds. At first, that error was tolerable, but after nearly a thousand years or so, the Christian Church began to face some problems. The easter and other holidays were slipping away from the seasons of the year that they are supposed to happen in. This prompted the Pope to decide on a fix.

Read more: Wikipedia

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How Pope Gregory XIII Decided to Fix the Calendar

Why October of 1582 is Missing 10 Days
Why October of 1582 is Missing 10 Days

To solve their problem, Pope Gregory XIII commissioned the astronomers and mathematicians to come up with a better calendar system. They created the Gregorian calendar, which states that centuries not divisible by 400 will not be leap years. This meant that 1600 or 2000 were leap years, but 1700, 1800, and 1900 were not. This new system fixed the problem, as the average year was now 365.2425 days, which is very close to the real solar year, matching the holidays and the seasons.

But, there is one more problem left. Changing the calendar should fix the future issues. However, it would not do the same for the 10 days that have already built up over the years. So, catholic countries such as Spain, Portugal, Italy, and Poland followed the reformers and skipped 10 days. They selected October due to its low major religious festivals, and it also did not disrupt the winter and spring seasons in the calendar.

Author's Final Thoughts

October 1582 did not lose 10 days because of an accident or some horrible disaster. Instead, it was purposely reformed in order to prevent the slow mistakes that were accumulating from the old Julian calendar.

By dropping those 10 days, Pope Gregory XIII and his people were able to align our calendar system closer to the Sun and the seasons. So, today, almost every country uses the Gregorian calendar, and most people will still be shocked to find out the hidden history behind it.

Read next: Why Do People Tend to Wake Up Earlier as They Age? — Here’s the Science Behind It

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Christian Ashford

Christian Ashford is a writer and researcher at Webpreneurships.com, a tech, information, and media company dedicated to publishing educational, informational, and curiosity-driven content. With a Bachelor of Science in Computer Science degree and experience in academic research, he combines technical expertise with a passion for exploring knowledge about the world and beyond. For over 13 years, Christian has researched, written, and edited hundreds of articles on science, history, business, technology, human origins, and more.