Here's Why October 1582 Lost 10 Days in This Fascinating Historical Event

Looking at calendars was pretty easy, as people just checked their phones and opened the apps. But back in 1582, when calendars were the main source of information about events and celebrations, something strange happened. In October of that year, 10 days suddenly disappeared, confusing everyone. People hoped the reason behind this wasn’t some bad omen or unfortunate sign.

Historians credited this mix-up to Julius Caesar and his great-nephew Augustus, as reported by UNILAD . In 46 BC, Julius Caesar tried to fix the calendar, creating the Julian Calendar named after him. According to the Julian calculation, the year was supposed to be 365.25 days long, but it was shorter about 365.2425 days. This small difference of 11 minutes and 14 seconds resulted in a 10-day gap in the calendar by 1582. Additionally, October was chosen to skip days because it had fewer religious holidays, so the ceremonial calendar would not be disrupted.

Knewz.com noted that since the sun didn't follow the calendar's timings, the seasons and dates began to perplex everyone. It became difficult to determine fixed dates for events like Easter and the March Equinox. Puzzled by the situation, the Council of Trent turned to the Pope to address this issue. At that time, Pope Pius IV was supposed to solve it, but he died. Twenty years later, Pope Gregory XIII took over and created a new calendar, naming it the Gregorian Calendar.

Since the dates of Easter were being affected, Pope Gregory XIII skipped ten days, so Thursday, October 4, 1582, was followed by Friday, October 15. People who went to sleep on October 4 woke up on October 15. However, there wasn’t much difference between the two calendar systems; the only variation was in how the leap year was calculated. According to IIFLScience , the Julian Calendar added a day every four years, while the Gregorian Calendar added a day every four years unless the year could be divided by 100 but not by 400. Both calendars had 12 months with 28 to 31 days, including a leap day in February every few years.

Spain, France, and Italy immediately adopted the new reformed calendar. Other countries made the changes later. For example, England switched from the Julian calendar to the Gregorian calendar in 1752, and Sweden made the change in 1753. Japan adopted it in 1873, China in 1912, Greece in 1923, Russia in 1918, and Turkey in 1927. Additionally, many non-Catholic Christian countries still relied on the Julian calendar for their religious dates, meaning that Catholic Easter and Orthodox Easter were not celebrated on the same day.

Several other names were associated with fixing the calendar. In 2012, Dr. Ana María Carabias published a book titled Salamanca and the Measurement of Time , emphasizing the contribution of scientists from the University of Salamanca to the Gregorian calendar. According to her research, reports suggesting ways to fix the misalignment were still kept in the Vatican Apostolic Library.

As of 2023, Ukraine decided to celebrate its holidays according to the Gregorian calendar, moving Christmas from January 7 to December 25. William Shakespeare and Miguel de Cervantes, who wrote Don Quixote , both died on April 23, 1616. However, since Spain used the Gregorian calendar and England did not, Shakespeare's death was recorded 10 days later. Many other countries later switched to the Gregorian calendar, but Ethiopia, Nepal, Iran, and Afghanistan did not adopt it.