Got a smart phone? Scroll your calendar to the year 1582, month October! What you see are 10 days missing from the month. October-4 is immediately followed by October-15.
Surprised at this anomaly? Well, actually, this mysterious disappearance is not an abnormality but a precisely planned reform aimed at correcting centuries-old inaccuracies in the Julian calendar.
the Julian calendar, which was in use since its introduction by Julius Caesar in 45 BCE, was increasingly out of sync with the solar year. The Julian system assumed a year was 365.25 days long, but the actual length of the solar year is slightly shorter, about 365.2425 days.
This discrepancy of roughly 11 minutes per year had accumulated over the centuries, causing the calendar dates to drift significantly from the actual seasons.
This growing misalignment, particularly impacted determining the date of Easter. So Pope Gregory XIII initiated a reform in 1582 and introduced a new calendar called the ‘Gregorian calendar’, named after the Pope.
The new calendar aimed to realign the dates with the seasons and to do that 10 days from the calendar that year needed to be deleted.
The Great Adjustment happened on October 4 that year, and therefore after October 4, the next day was October-15.
Initially Roman Catholic countries such as Italy, Spain, and Portugal adopted this calendar, the others were slower to adopt it.
For instance, Great Britain and its colonies didn’t make the switch until 1752, when they had to skip 11 days.
Russia clung to the Julian calendar until after the Bolshevik Revolution in 1918, resulting in a 13-day difference by then
Today, the Gregorian calendar is the internationally accepted civil calendar.
