Century leap year: Difference between revisions
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The Gregorian calendar was introduced in 1582, but was adopted by various countries at different times over several centuries. Dates prior to 1582 are generally recorded using the Julian calendar, and different countries have different conventions about how to record dates between 1582 and their [[adoption of the Gregorian calendar]].{{efn|See, for example, [[Old Style and New Style dates]].}} Consequently, for example, the year 1700 was a leap year in the British and Russian empires but not in most of the rest of Europe; 1800 and 1900 were still leap years in the Russian empire but not generally elsewhere.{{efn|Other exceptions are listed at [[adoption of the Gregorian calendar]].}} |
The Gregorian calendar was introduced in 1582, but was adopted by various countries at different times over several centuries. Dates prior to 1582 are generally recorded using the Julian calendar, and different countries have different conventions about how to record dates between 1582 and their [[adoption of the Gregorian calendar]].{{efn|See, for example, [[Old Style and New Style dates]].}} Consequently, for example, the year 1700 was a leap year in the British and Russian empires but not in most of the rest of Europe; 1800 and 1900 were still leap years in the Russian empire but not generally elsewhere.{{efn|Other exceptions are listed at [[adoption of the Gregorian calendar]].}} |
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The century common year 3100 begins on a Monday and ends on a Monday, but it is followed by the century leap year 3200, as well as the century common years that begin on Friday, Wednesday, and Monday of 3300, 3400 and 3500, and the century leap year 1600, and the century common years that begin on Friday, Wednesday, and Monday, like 3700, 3800, 3900, and the final century leap year 4000 that starts on Saturday and ends on Sunday. The end of 3300, 3400, and 3500 is the same on Friday, Wednesday and Monday. |
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==Notes== |
==Notes== |
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Revision as of 18:53, 5 June 2024
 | This article needs additional citations for verification. (December 2020) |
A century leap year is a leap year in the Gregorian calendar that is evenly divisible by 400.[1]
Like all leap years, it has an extra day in February for a total of 366 days instead of 365. In the obsolete Julian calendar, all years that were divisible by 4, including end-of-century years, were considered leap years. The Julian rule, however, adds too many leap days (about 3 extra leap days in 400 years), which resulted in the calendar drifting gradually with respect to the astronomical seasons. To remedy this, Pope Gregory XIII introduced in 1582 a slightly modified version of the Julian calendar, the Gregorian calendar, where century years are leap years only if they are divisible by 400. This eliminates 3 of the 4 end-of-century years in a 400-year period. For example, the years 1600, 2000, 2400, and 2800 are century leap years since those numbers are evenly divisible by 400, while 1700, 1800, 1900, 2100, 2200, 2300, 2500, 2600, 2700, 2900, and 3000 are common years despite being evenly divisible by 4. This scheme brings the average length of the calendar year significantly closer to the astronomical length of the year, nearly eliminating the drift of the calendar against the seasons.
The Gregorian calendar was introduced in 1582, but was adopted by various countries at different times over several centuries. Dates prior to 1582 are generally recorded using the Julian calendar, and different countries have different conventions about how to record dates between 1582 and their adoption of the Gregorian calendar.[a] Consequently, for example, the year 1700 was a leap year in the British and Russian empires but not in most of the rest of Europe; 1800 and 1900 were still leap years in the Russian empire but not generally elsewhere.[b] The century common year 3100 begins on a Monday and ends on a Monday, but it is followed by the century leap year 3200, as well as the century common years that begin on Friday, Wednesday, and Monday of 3300, 3400 and 3500, and the century leap year 1600, and the century common years that begin on Friday, Wednesday, and Monday, like 3700, 3800, 3900, and the final century leap year 4000 that starts on Saturday and ends on Sunday. The end of 3300, 3400, and 3500 is the same on Friday, Wednesday and Monday.
Notes
- ^ See, for example, Old Style and New Style dates.
- ^ Other exceptions are listed at adoption of the Gregorian calendar.
References
- ^ "Introduction to Calendars". United States Naval Observatory. n.d. Retrieved 9 May 2022.
Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the year 2000 is.
External links
- An Introduction to Calendars courtesy of the United States Naval Observatory Archived 2019-06-13 at the Wayback Machine
- Frequently Asked Questions about Calendars
- History of Gregorian Calendar
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