Friday, October 15, 1582 was the first day of the modern Gregorian calendar. The previous day was Thursday, October 4, 1582 of the Julian calendar.
While very similar to the Gregorian calendar, the Julian calendar contained 365 days a year, and added a leap day in February every four years. Unfortunately, a solar year is actually 365.2422 (mean tropical year) to 365.2424 (vernal equinox year) days long. With the Julian calendar assuming it was 365.25 days long, every 128 to 131 years, the calendar would gain an extra day. After several centuries of use, it became noticeable that the seasons were getting out of sync with the calendar. The Roman Catholic Church was especially troubled that Easter was occurring at the wrong time of year.
To solve this problem, Pope Paul III enlisted the aid of several astronomers including Christopher Clavius to try and solve this problem. Built upon the ideas of the deceased physician and astronomer Luigi Lilio and later enacted under the next leader of the church, Pope Gregory XIII, the new Gregorian system made the following changes:
- Ten days were removed from the calendar, and it was decreed that the day following Thursday, October 4, 1582 (i.e., October 5, 1582 of the Julian calendar) would be known as Friday, October 15, 1582.
- Instead of a simply determining a year was a leap year if it was divisible by four, in the Gregorian calendar a year is a leap year if either:
- it is divisible by 4 but not by 100
or
- it is divisible by 400.
Thus the years 1600 and 2000 are leap years, but 1700, 1800, 1900 and 2100 are not.
- New rules for determining the date of Easter were adopted.
- The position of the extra day in a leap year was moved from the day before February 25th to the day following February 28th.
The Catholic countries of Italy, Spain, Portugal, Poland, France, and Luxembourg quickly made the switch to the new calendar, other Catholic countries followed within the next several years. Since this change was created by the Roman Catholic Church, numerous Protestant and Greek Orthodox countries did not make the switch for several decades or even centuries. This causes some serious confusion for historians and genealogists including simple things like calculating the day of the week for a certain date. Below is a chart listing the dates that several nations officially adopted the new calendar system.
Country End Julian Calendar Begin Gregorian Calendar
Albania Dec 1912 Dec 1912
Austria
Tyrol Oct 5, 1583 Oct 16, 1583
Carinthia, Styria Dec 14, 1583 Dec 25, 1583
Belgium
Spanish Provinces Dec 21, 1582 Jan 1, 1583
Liège Feb 10, 1583 Feb 21, 1583
Bohemia (Czech Republic) Jan 6, 1584 Jan 17, 1584
Bulgaria Nov 1, 1915 Nov 14, 1915
China Dec 18, 1911 Jan 1, 1912
Canada Sep 2, 1752 Sep 14, 1752
Denmark Feb 18, 1700 Mar 1, 1700
Færø Islands Nov 16, 1700 Nov 28, 1700
Egypt 1875 1875
Estonia Feb 1, 1819 Feb 15, 1819
Finland Feb 17, 1753 Mar 1, 1753
France Dec 9, 1582 Dec 20, 1582
Alsace 1648 1648
Strasbourg Feb 5, 1682 Feb 16, 1682
Germany, Catholic Regions
Augsburg Feb 13, 1583 Feb 24, 1583
Baden Nov 16, 1583 Nov 27, 1583
Bavaria Oct 5, 1583 Nov 16, 1583
Cologne Nov 3, 1583 Nov 14, 1583
Jülich Nov 2, 1583 Nov 13, 1583
Mainz Nov 11, 1583 Nov 22, 1583
Münster, Strasbourg Nov 16, 1583 Nov 27, 1583
Trier Oct 4, 1583 Oct 15, 1583
Würzburg Nov 4, 1583 Nov 15, 1583
Germany, Protestant Regions
Hildesheim Mar 15, 1631 Mar 26, 1631
Kurland 1617 1617
Minden Feb 1, 1668 Feb 12, 1668
Neuburg Dec 13, 1615 Dec 24, 1615
Osnabrück 1624 1624
Paderborn Jun 16, 1585 Jul 27, 1585
Prussia Aug 22, 1610 Sep 2, 1610
Westphalia Jul 1, 1584 Jul 12, 1584
All Others Feb 18, 1700 Mar 1, 1700
Great Britain Sep 2, 1752 Sep 14, 1752
& American colonies
Greece Sep 14, 1916 Sep 28, 1916
Holy Roman Empire Jan 6, 1584 Jan 17, 1584
Hungary Oct 21, 1587 Nov 1, 1587
Transylvania Dec 14, 1590 Dec 25, 1590
Iceland Nov 16, 1700 Nov 28, 1700
Italy Oct 4, 1582 Oct 15, 1582
Japan 1873 1873
Latvia Feb 1, 1918 Feb 15, 1819
Lithuania Feb 1, 1918 Feb 15, 1819
Moravia (Czech Republic) Jan 6, 1584 Jan 17, 1584
The Netherlands
Holland, North Brabant Dec 21, 1582 Jan 1, 1583
Gelderland, Zutphen Jun 30, 1700 Jul 7, 1700
Utrecht, Overijssel Nov 30, 1700 Dec 12, 1700
Friesland, Groningen Dec 31, 1700 Jan 12, 1701
Drente Apr 30, 1701 May 12, 1701
Norway Feb 18, 1700 Mar 1, 1700
Poland Oct 4, 1582 Oct 15, 1582
Silesia Jan 12, 1584 Jan 23, 1584
Portugal Oct 4, 1582 Oct 15, 1582
Romania Mar 31, 1919 Apr 14, 1919
Transylvania Dec 14, 1590 Dec 25, 1590
Russia Jan 31, 1918 Feb 14, 1918
Spain Oct 4, 1582 Oct 15, 1582
American Colonies 1584 1584
Sweden Feb 17, 1753 Mar 1, 1753
Switzerland
Lucern, Uri, Schwyz, Jan 11, 1584 Jan 22, 1584
Zug, Freiburg,
Solothurn
Wallis Feb 28, 1655 Mar 11, 1655
Zürich, Bern, Basel, Dec 31, 1700 Jan 12, 1701
Schaffhouse, Geneva,
Thurgovia
Appenzell, Glarus, 1724 1724
St. Gallen
Turkey 1927 1927
United States
British Colonies Sep 2, 1752 Sep 14, 1752
Alaska Oct 5, 1867 Oct 18, 1867
Yugoslavia Mar 4, 1919 Mar 18, 1919
See also:
References
- http://www.searchforancestors.com/utility/gregorian.html
- http://serendipity.magnet.ch/hermetic/cal_stud/cal_art.htm