Gregorian and Julian calendars

Part of our occasional series, Interesting but useless trivia. Trivia that is certainly interesting, but yeah, pretty useless in the grand scheme of things. Not likely to result in a promotion, raise, or your next big career move.

In this latest installment of "Interesting but useless trivia," we look at the roots of the calendar system that we go by.

Pope Gregory XIII instituted the Gregorian calendar system.

The calendar has its roots deeply planted in Rome. Most of the world uses what's known as the Gregorian calendar. According to Wikipedia, “The Gregorian calendar is internationally the most widely used civil calendar. It is named after Pope Gregory XIII, who introduced it in October 1582.”

Prior to the Gregorian calendar, the Julian calendar, introduced by Julius Caesar in 46 BC, had been the dominant civil calendar used in the world, and, in fact, the Julian calendar was, according to an article on timeanddate.com, “...still used by some countries into the early 1900s. Some Orthodox churches still use it today to calculate the dates of moveable feasts, such as the Orthodox Church in Russia. Others who still use the Julian calendar include the Berber people of North Africa and on Mount Athos.”

Julius Caesar

When looking up the birth dates of certain historic figures, or the dates of certain historic events, you may see two dates given. One is designated as O.S. (for Old Style), and the other as N.S. (New Style). An O.S. date refers to the Julian calendar, while the N.S. date goes by the Gregorian.

Today, the difference between the two calendars is now at 13 days, with the Julian calendar trailing behind the Gregorian. The main difference between the two calendars has to do with calculating leap years. The Julian calendar has too many leap years, and so the goal of the Gregorian is to correct this and provide for a more accurate calendar.

For further information:

https://en.wikipedia.org/wiki/Gregorian_calendar

https://www.timeanddate.com/calendar/julian-calendar.html