Gregorian Calendar
Contents
General
Greeks Proleptic Gregorian Calendar Change from Julian to Gregorian Calendar Change from Julian to Gregorian Calendar: Special Cases |
General
- proposed by Aloysius Lilius, introduced by Pope Gregory XIII February 24 1582 to replace Julian calendar
- tropical year ~365+(97/400) days; takes 3300 years for the tropical year to shift back 1 day
- 97 leap years every 400 years
- every year divisible by 4 is a leap year except for centurial years which must be exactly divisible by 400 to be leap years
- proposed 4000-year rule: suggested by astronomer John Herschel that better approximation of tropical year would be 365 + (969/4000) days = 365.24225 days
- 969 leap years every 4000 years instead of 970 years
Greeks
- Orthodox church in Greece switched to Gregorian calendar in 1920s
- Tried to improve leap year rule
- Every year which when divided by 900 leaves a remainder of 200 or 600 is a leap year
- Conflicts with rest of world in 2800
- 218 leap years every 900 years: 365 + (218/900) = 365.2425 days
- not official in Greece
Proleptic Gregorian Calendar
- Proleptic calendar: extrapolation of a calendar prior to its date of introduction
- extrapolation uses convention that the year prior to year 1 is year 0
- differs from Julian Calendar (no year 0)
- December 30th, 0 in Gregorian proleptic calendar corresponds to January 1st, 1 in Julian Calendar
Change from Julian to Gregorian Calendar
Albania: December 1912
Austria: Different regions on different dates
Bulgaria: 31 Mar 1916 was followed by 14 Apr 1916
Canada: Different areas changed at different times.
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
Greece: 15 Feb 1923 was followed by 1 Mar 1923
Hungary: 21 Oct 1587 was followed by 1 Nov 1587
Italy: 4 Oct 1582 was followed by 15 Oct 1582
Japan: The Gregorian calendar introduced to supplement 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:
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 [Greek Orthodox parts may have changed later.]
Russia: 31Jan1918 was followed by 14 Feb 1918 [east parts: change may not have occurred until 1920.]
Spain: 4 Oct 1582 was followed by 15 Oct 1582
Sweden (including Finland): 17 Feb 1753 was followed by 1 Mar 1753 (see note below)
Switzerland:
USA: Different areas changed at different times.
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
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
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
- 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)
Greece: 15 Feb 1923 was followed by 1 Mar 1923
Hungary: 21 Oct 1587 was followed by 1 Nov 1587
Italy: 4 Oct 1582 was followed by 15 Oct 1582
Japan: The Gregorian calendar introduced to supplement 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:
- Zeeland, Brabant, 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
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 [Greek Orthodox parts may have changed later.]
Russia: 31Jan1918 was followed by 14 Feb 1918 [east parts: change may not have occurred until 1920.]
Spain: 4 Oct 1582 was followed by 15 Oct 1582
Sweden (including Finland): 17 Feb 1753 was followed by 1 Mar 1753 (see note below)
Switzerland:
- Catholic cantons: 1583, 1584 or 1597
- Protestant cantons: 31 Dec 1700 was followed by 12 Jan 1701
- (Many local variations)
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.
Change from Julian to Gregorian Calendar: Special Cases
Sweden
Sweden decided to make a gradual change from the Julian to the Gregorian calendar. By dropping every leap year from 1700 through 1740 the eleven superfluous days would be omitted and from 1 Mar 1740 they would be in sync with the Gregorian calendar. (But in the meantime they would be in sync with nobody)
Sweden decided to make a gradual change from the Julian to the Gregorian calendar. By dropping every leap year from 1700 through 1740 the eleven superfluous days would be omitted and from 1 Mar 1740 they would be in sync with the Gregorian calendar. (But in the meantime they would be in sync with nobody)
- 1700: (should be leap year in Julian Calendar) not a leap year in Sweden
- by mistake, 1704 and 1708 become leap years
- Sweden out of sync with both Julian an Gregorian calendars
- Went back to Julian Calendar: extra day in 1712 (turned into double leap year, Feb has 30 days)
- 1753: changed to Gregorian Calendar by dropping 11 days
- refers to an act of the British parliament in that year which finally adopted the Gregorian calendar and set the beginning of the (English) year to 1 January, rather than 25 March
- can be some confusion about year, prior to 1752, for dates between January and March
- Scotland’s New Year’s Day had already been set to 1 January since 1600
- Dates in the Julian calendar are usually denoted “Old Style”, with those in the Gregorian “New Style
- Act was passed in 1751 but didn’t come into operation until following year