September, the ninth month in the year, comes from the Latin sept — seven; and is followed by October, from the Latin octo — eight. November and December are similarly designated in Latin ninth and tenth — so how did they come to be marked two months later? Because sometime around the ninth century A.D. Southern Europe began marking the beginning of the year in March 25th, the date of the “annunciation”, when the Angel Gabriel announced to Mary she would give birth to Christ. That “old-style” Julian calendar was phased out, starting in the 16th century,

On this day, September 14, in 1752 the British Empire switched completely to the Gregorian calendar, named for Pope Gregory XIII. For two centuries prior it had used two different calendars, making a complicated datekeeping system even more confusing by marking two different starts to the year.

Combined with an imprecise measurement of the solar year, the March start to the years made the dates as marked by the Julian push the equinoxes far from their expected time, and some holidays fall on not only the wrong month, but the wrong season. As one of the Protestant countries, Britain ignored the Papal decree for the better part of three centuries; when they finally switched over, some 11 days had to be dropped from September to align it with the new date.