We’ve all scrolled back through the calendars on our phones to look up interesting dates.
It’s one way to find out which day of the week you were born, for example, or just to double check the dates of past events.
But if you scroll back far enough – and we mean really, really far – you’ll come across something a bit unusual.
October 1582 isn’t exactly a year which went down in history. It certainly doesn’t have the same familiarity as 1066 (the Battle of Hastings), 1969 (the US moon landing) or 1914 (the start of World War I).
But one historical event, decided in February of that year and coming into effect on October 5, completely changed the way we recognise dates.
This was when Pope Gregory XIII decided to implement a new, reformed calendar – known as the Gregorian calendar in his honour.
But what calendar was used before this and why did the church decided to make the change? Metro has the answers.
The Gregorian calendar we still use today was preceded by the Julian calendar, which in turn was preceded by the Roman republican calendar.
The Julian calendar was used for the first millennium and part of the second millennium – but it featured an error which, though it seems small in hindsight, added up over time.
It was 11 minutes and 14 seconds than the tropical year, which is the time it takes for the sun to return to the same position, as seen from earth.
This meant the calendar drifted by about one day for every 314 years.
For the church, one of the most pressing issues caused by this was the difficulty in calculating the date of Easter each year.
The Council of Nicaea decreed in 325 that it should fall on the first Sunday following the first full moon after the vernal equinox – which at that time, fell on March 21.
So, the shifting Julian calendar meant the gap between the date set by the council and the actual vernal equinox began to grow, and a number of ideas to fix this problem were presented to various popes throughout the Middle Ages.
No action was taken, however, with the Julian calendar continuing to be used until 1562-63. The Council of Trent passed a decree calling for the pope to fix the calendar – but it took another two decades for a solution to be found.
The reforms were based on suggestions from Italian scientist Luigi Lilio, which were modified by Jesuit mathematician and astronomer Christopher Clavius.
Following 20 years of research and consultation, Pope Gregory XIII signed a papal bull in February 1582, ordering that the new calendar would be brought into effect on October 5 of that year.
Dropping 10 days from the calendar moved the vernal equinox from March 11 to March 21, and the move was done in October to ensure no major Christian festivals were skipped.
The Gregorian calendar wasn’t immediately adopted across the globe, however, as Protestant and Orthodox countries didn’t want to take orders from the pope.
Catholic countries including Austria, Spain, Portugal, Italy, Poland, and Germany’s Catholic states, jumped ahead of the rest of Europe by 10 days – meaning crossing borders often meant travelling back or forwards in time.
But eventually, non-Catholic countries started adopting the Gregorian calendar.
The Protestant regions of Germany and the Netherlands made the switch in the 17th century, and Britain and the territories of the British Empire followed suit in 1752, spreading the calendar around the world.
So, if you’ve ever been bored enough to scroll that far back in your phone’s calendar and wondered where those 10 missing days went, there’s your answer.
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