On this day, February 24, 1582, Pope Gregory XIII announced the Gregorian calendar with the papal bull (public decree) Inter gravissimas. The primary reason for this reform was to address the calendar's drift concerning the equinoxes and solstices.
Before the Gregorian calendar, the Julian calendar, introduced by Julius Caesar in 46 BC, counted a year as 365.25 days, with an extra day added every four years for leap years. However, this calculation was slightly off, leading to a cumulative drift of approximately 11 minutes per year. By the 16th century, the calendar had drifted significantly; the spring equinox had moved from March 21 to around March 11. Pope Gregory XIII decided to implement a reform to realign the calendar with the seasons.
The Gregorian calendar was first implemented in October 1582 in Catholic countries such as Italy, Spain, Portugal, Austria, and Poland. The day after October 4, 1582, became October 15, 1582, skipping 10 days to correct the drift. At first, Protestant and Orthodox nations refused to adopt it, unwilling to follow the Pope's direction. This most certainly caused problems and headaches, to be sure! Consequently, crossing a border meant traveling backward and forward on a calendar. Talk about time travel. That’s enough to make Marty McFly’s head spin!
Others were also slow to join the party. Great Britain and its colonies transitioned in 1752, skipping 11 days (September 2 was succeeded by September 14). Russia did not adopt the calendar until 1918, following the Bolshevik Revolution, which led to the calendar change that year, where January 31 was succeeded by February 14. However, over the following centuries, the Gregorian calendar became the worldwide standard, and today, it is widely used for civil purposes.
The featured images come from:
Wisconsin Artists Calendar published in Milwaukee, WI by Wisconsin Printmakers, 1936.
A Calendar: Twelve Poems by Robert Creeley. It was published in
West Branch, Iowa byCoffee House Press, 1984.
Wisconsin Poets' Calendar published in Fairwater, WI by Midwestern Writers' Publishing House, 1983.
The Cynic's Calendar of Revised Wisdom for 1904 by Oliver Herford, Ethel Watts Mumford, and Addison Mizner. It was published in San Francisco by Paul Elder and Company, 1903.
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--Melissa, Special Collections Library Assistant