Why was 11 days removed from the the month of September in 1752?

What could it have felt like, slept September 2nd, to wake on 14th September? This was the experience of over six and a half million Britons who went to bed on September 2, 1752, and woke up on September 14 of the same year. What then happened to the missing 11 days of September 1752?

The 11 lost days of September 1752


This was simply because of 11 minutes difference. Yes you heard right, just 11 minutes lead to the disappearance of 11 days in the September 1752 calendar.

The Julian calendar considered one year is equal to 365 days, 5 hours and 49 minutes (325.25 days) and started adding 1 day for every 4 years.  So every 4th year became leap year.  To make this easier, every year divisible b 4 became leap years.

In 1582, during his 10th year as Pope, Gregory XIII realized a problem with getting the accurate date for Easter. This lead to the discovery that one solar year is equal to 365 days, 5 hours and 49 minutes (365.24217898 days)

The eleven minutes difference between the the Julian calendar and the complete solar year might seem insignificant, but when added up for a period of 1,410 years, we realize it adds up to 11 days.

for example, 365.25 days – 365.24217898 days = 0.00782101999 days. This is obviously insignificant in a year, but then, let’s see the accumulation over 1410 years; 0.00782101999 x 1410 = 11.03 days

This explains why getting the actual Easter date became a problem for Gregory XIII. Other important dates are celebrated later than their actual date, for example, Christmas would be celebrated 11 days later than the actual date after the first 15 centuries and 22 days later after 30 centuries and so on…

What is needed to be done?

To correct this anomaly, Pope Gregory called upon an Italian mathematician and scientist Alosius Lilius and asked him to make a new calendar which addresses the above issue.

Upon completion, Pope Gregory XIII released a papal bull (a declaration from the leader of the Catholic church) decreeing that those under the dominion of his church would have to remove 10 days from October 1582 calendar.

October 1582

So October 1582 contained only 21 days that year. Spain, Italy, Netherlands, France, Portugal, Luxembourg, Poland and Lithuania all adopted Gregory’s bull that year.

50 years later, Austria, Switzerland, Germany, Hungary, and Prussia joined in using the new Gregorian calendar.

September 1752 CalendarSome, especially the protestants didn’t adopt the new calendar because they felt it might be another conspiracy by the Church. But about 200years later, the protestant countries (Britain, Americas and other colonies) realized in other to stay in time, the change was necessary. So, they changed their calendars in 1752 by removing 11 days from September 1752.


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