Before the Gregorian calendar, most countries relied on the Julian calendar, which was introduced by Julius Caesar in 45 BC. It was in common use until the 1500s. The Julian calendar creates an error of 1 day every 128 years.

 

The Gregorian calendar was proposed by Aloysius Lilius, a physician from Naples, and adopted by Pope Gregory XIII in accordance with the instructions from the Council of Trent (1545-1563) to correct for errors in the older Julian calendar. It was decreed by Pope Gregory XIII in a papal bull on February 24 1582. This bull was named “Inter Gravissimas” after its first two words.

 

It took time to switch to the new calendar. The following list contains the dates for changes in a number of different countries:

 

Albania: December 1912

 

Austria: Different regions on different dates.

               Brixen, Salzburg and Tyrol: 5 Oct 1583 was followed by 16 Oct 1583

               Carinthia and Styria: 14 Dec 1583 was followed by 25 Dec 1583

               See also Czechoslovakia and Hungary

 

Belgium: See the Netherlands

 

Bulgaria: 31 Mar 1916 was followed by 14 Apr 1916

 

Canada: Different areas changed at different times.

               Newfoundland and Hudson Bay coast:  2 Sep 1752 was followed by 14 Sep 1752

               Mainland Nova Scotia: Gregorian 1605 - 13 Oct 1710

                                               Julian 2 Oct 1710 - 2 Sep 1752

                                               Gregorian since 14 Sep 1752

               Rest of Canada: Gregorian from first European settlement

 

China: The Gregorian calendar replaced the Chinese calendar in 1912, but the Gregorian calendar

was not used throughout the country until the communist revolution of 1949.

 

Czechoslovakia (i.e. Bohemia and Moravia): 6 Jan 1584 was followed by 17 Jan 1584

 

Denmark (including Norway): 18 Feb 1700 was followed by 1 Mar 1700

 

Egypt: 1875

 

Estonia: 31 Jan 1918 was followed by 14 Feb 1918

 

Finland: Then part of Sweden. (Note, however, that Finland later became part of Russia, which

then still used the Julian calendar. The Gregorian calendar remained official in Finland, but

some use of the Julian calendar was made.)

 

France: 9 Dec 1582 was followed by 20 Dec 1582

             Alsace: 5 Feb 1682 was followed by 16 Feb 1682

             Lorraine: 16 Feb 1760 was followed by 28 Feb 1760

             Strasbourg: February 1682

 

Germany: Different states on different dates.

                 Catholic states on various dates in 1583-1585

                 Prussia: 22 Aug 1610 was followed by 2 Sep 1610

                 Protestant states: 18 Feb 1700 was followed by 1 Mar 1700

                 (Many local variations)

 

Great Britain and Dominions: 2 Sep 1752 was followed by 14 Sep 1752

 

Greece: 9 Mar 1924 was followed by 23 Mar 1924 (Some sources say 1916 and 1920)

 

Hungary: 21 Oct 1587 was followed by 1 Nov 1587

 

Ireland: See Great Britain

 

Italy: 4 Oct 1582 was followed by 15 Oct 1582

 

Japan: The Gregorian calendar was introduced to supplement the traditional Japanese calendar

on 1 Jan 1873.

 

Latvia: During German occupation 1915 to 1918

 

Lithuania: 1915

 

Luxemburg: 14 Dec 1582 was followed by 25 Dec 1582

 

Netherlands (including Belgium):

         Zeeland, Brabrant, and the “Staten Generaal”: 14 Dec 1582 was followed by 25 Dec 1582

         Holland: 1 Jan 1583 was followed by 12 Jan 1583

         Limburg and the southern provinces (currently Belgium): 20 Dec 1582 was followed by 31 Dec 1582

                                                                                          Or 21 Dec 1582 was followed by 1 Jan 1583

         Groningen: 10 Feb 1583 was followed by 21 Feb 1583

                          Went back to Julian in the summer of 1594

                          31 Dec 1700 was followed by 12 Jan 1701

         Gelderland: 30 Jun 1700 was followed by 12 Jul 1700

         Utrecht and Overijssel: 30 Nov 1700 was followed by 12 Dec 1700

         Friesland: 31 Dec 1700 was followed by 12 Jan 1701

         Drenthe: 30 Apr 1701 was followed by 12 May 1701

 

Norway: Then part of Denmark.

 

Poland: 4 Oct 1582 was followed by 15 Oct 1582

 

Portugal: 4 Oct 1582 was followed by 15 Oct 1582

 

Romania: 31 Mar 1919 was followed by 14 Apr 1919 (The Greek Orthodox parts of the country may have changed later)

 

Russia: 31 Jan 1918 was followed by 14 Feb 1918 (In the eastern parts of the country the change may not have occurred until 1920)

 

Scotland: Much confusion exists regarding Scotland’s change. Different authorities disagree about

whether Scotland changed together with the rest of Great Britain, or if they had changed earlier.

 

Spain: 4 Oct 1582 was followed by 15 Oct 1582

 

Sweden (including Finland): 17 Feb 1753 was followed by 1 Mar 1753

 

Switzerland: Catholic cantons: 1583, 1584 or 1597

                      Protestant cantons: 31 Dec 1700 was followed by 12 Jan 1701 (Many local variations)

 

Turkey: Gregorian calendar introduced 1 Jan 1927

 

USA: Different areas changed at different times.

         Along the Eastern seaboard: With Great Britain in 1752.

         Mississippi valley: With France in 1582.

         Texas, Florida, California, Nevada, Arizona, New Mexico: With Spain in 1582

         Washington, Oregon: With Britain in 1752.

         Alaska: October 1867 when Alaska became part of the USA.

 

Wales: See Great Britain

 

Yugoslavia: 1919

 

Because of this transition, the Gregorian calendar will not calculate dates that are consistent with the Julian calendar prior to the date that Gregorian calendar was introduced.

 

The Julian and later the Gregorian calendars were designed to reflect the motion of the earth around the sun. The year is the actual length of time it takes for the Earth to complete one orbit around the Sun. The Gregorian calendar has a regular years = 365 days and a leap years = 366 days. The leap year (29 days in February) has one more day than a regular year (28 days in February).

 

Leap year rules:

  • Every year divisible by 4 is a leap year

  • However, every year divisible by 100 is not a leap year

  • However, every year divisible by 400 is a leap year after all

 

For people in the northern hemisphere:

  • The shortest day of the year is near December 21

  • The longest day is near June 21

  • The days when day and night have approximately the same length is near March 20 and September 22

 

For people in southern hemisphere these events are shifted half a year.

 

 

The Gregorian calendar today serves as an international standard for civil use, and NaturCalendar™ is based on the Gregorian calendar.

 

 

References:

 

“Frequently Asked Questions about Calendars”, Claus Tøndering, 28 October 2001, Copyright ©2001 by Claus Tøndering.

 

 

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