Gregorian calendar

the Gregorian calendar, designated after Pope Gregor XIII., today in most parts of the world valid calendars are.

Table of contents

Gregorian calendar reform

the first council of Nikaia|Nikaia|Nicäa determined in the year 325 that Easter always on first Sunday after the first full moon afterSpring beginning (related to Jerusalem) to be celebrated should. The astronomical event of the prime acre equinox (spring-day-and-night-same of the northern half of our planet) found in the council year 325 to 21. March instead of, and the Julian intercalary day regulation was recognized at that time not yet as in need of improvement. That at that timevalid Julian calendars proceeded from a middle sun year from 365,25 days and adjusted the difference (related to 365 days) of approximately 6 hours every four years by the insertion of an intercalary day. In relation to of the actual course celestial mechanicsastronomically given sun year, that in the year 2000 on 365,242190517 days - thus about 365 days, 5 hours, 48 minutes and 45.25 seconds - was the year of the Julian calendar was determined thus somewhat more than 11 minutes too long. Toin 16. Century, at present Pope Gregors XIII., this error had affected itself in such a way that the prime acre equinox in the year 1582 already at the 11. March took place.

This shift of the calendar had become before obvious however already longer time. Sincethat 14. Century suggestions for a calendar reform were submitted again and again - among other things by Nikolaus of Kues on behalf the council by Basel, Regiomontanus and Nikolaus Kopernikus. These had been however always rejected. Nevertheless Kopernikus' formed work DeRevolutionibus Orbium Coelestium (“of the revolutions of the heavenly bodies”) as well as the prutenischen boards of Erasmus Reinhold the basis for finally of Pope the Gregor XIII. dekretierte reform.

With the mathematical elaboration of the new switching rules in Rome as a mathematician the teaching becameGerman Jesuit Christophorus Clavius already 1579 of the Pope assigns.

Around the spring-day-and-night-same again with that 21. March to harmonize and Easter again on the correct day to celebrate be able, followed the Pope the suggestion of the physician and hobby astronomer Aloisius Lilius and determined that in the year 1582 ten days should be jumped over. Therefore followed in some Roman-catholic countries on the 4. Equal October the 15. October - the succession of the weekdays remained however unchanged thereby. Thus the prime acre equinox foundthere in the subsequent year 1583 again to 21. March instead of; the time calculation within the Christianity was not uniform however any longer. Thus was the initial position, like it at present the council existed, again approximately manufactured.

Around renewed moving away 21. Marchfrom the time of the prime acre equinox for all future to avoid, the new Gregorian calendar specified the duration of the middle sun year on 365,2425 as before on 365,25 days. This Verkürzung took place via the fact that - deviating from the switching rule of the JulianCalendar - which do not have years an intercalary day, whose number can be divided without remainder by 100, not however by 400. In accordance with this rule it gave in the year 2000, whose year both by 100 and 400 divideleaves, 29. February. The year 2100 will have again no intercalary day, just as little 2200 and 2300. Only in the year 2400 the rule will be again fulfilled.

Because up to the first application of this new exception rule in the year 1700 still 117 yearspassed, the calendar in relation to the astronomical event of the prime acre equinox on the average 1 day moved themselves. Since that time it oscillates to 19 between that. and 21. March.

the switching rules

which year is not leap year and which?

See: Leap year, section of Gregorian calendars

introduction of the Gregorian calendar in different countries

only few countries such as Spain or Portugal actually took over the Gregorian calendar to 4./15. October 1582. Most Roman-catholic countries of Europe followed inthe next years, while the Protestant countries rejected the new calendar, because from the Pope dekretiert, first. For example it most catholic cantons of Switzerland introduced 1584 , whale-read however only 1655. There followed at that time on the 28. February the 11. March. The Evangelist territories of the holy Roman realm took over the Gregorian calendar only 1700. On the 18. February followed the 1 there directly. March 1700. Before for example contracts between catholic and Protestant princes had alsoboth data to be provided, approximately as 5. /15. October 1582. Over the turn of the year differed the years between the areas of the old and new calendar. From this time the expression originates” between the years “for the days after Christmas.

The Kingdom of Denmark, to that at that time also Norway, Iceland and Greenland belonged, led the Gregorian calendar likewise of 18. February on the 1. March 1700 . The reformed places of Switzerland followed scarcely one year later, them jumped of 31. December 1700 on the 12. January 1701, however with three exceptions: The Protestant half canton Appenzell Ausserrhoden and the Protestant parts of Glarus followed only 1724, and in grey federations the official transition took place to the new calendar to different datesfrom 1760 to 1812; the old calendar remained however even still longer in the population alive. The Appenzeller Silvesterkläuse becomes still to 31. December after the Julian calendar (13. January after the Gregorian calendar) celebrated. In England(and also in the later USA) the Gregorian calendar became at the night of 2. September on the 14. September 1752 imported.

The orthodox countries of Eastern Europe still kept the Julian calendar to beginning 20. Century. There thoseYears 1700, 1800 and 1900 were in Russia leap years, constituted the deviation from the Gregorian calendar there meanwhile 13 days. The Russian October Revolution 1917 fell therefore after the Gregorian calendar on the 7. November. On this daythe revolution was celebrated also up to the end of the Soviet Union, after Russia 1918 had introduced the new calendar calculation. Some orthodox churches (z. B. in Russia, Serbia and Georgien) its being certain celebrations commit further after the Julian calendar.Their Christmas (25. December) falls therefore at present on the 7. January (greg.). Other orthodox churches (z. B. in Greece and Bulgaria) use for this the neo Julian calendar in such a way specified, that up to the year 2799 the Gregorian calendarwill correspond. All orthodox churches compute Easter and the other mobile celebrations after the Julian spring beginning as well as after the metonischen full moon; the celebration coincides therefore only occasionally with the Osterdatum of the western churches; usually it is one, four, orfive weeks later than in the west.

As last state Turkey the Gregorian calendar took over 1926; there up to then the Islamic calendar had applied. The not contemporaneous introduction of the Gregorian calendar in the different countries provided for confusion, butalso for interesting paradoxes: Like that both William Shakespeare and Miguel de Cervantes are to 23. April 1616 died, although Shakespeare Cervantes survived by 11 days. Also the celebrations of the birthday of George Washington became occasionally at the 11. andto 22. February aligned, up to a federallegal holiday regulation. In (Protestant) Switzerland this very day the chamfering time is temporally shifted celebrated - as an indication not to want to bend itself the dictation of the Pope.


the rulesthe Gregorian calendar lead to an average length of the calendar year of 365,2425 or 365 + 97 400 days.

The so-called tropical year - the period lying between two following each other prime acre equinoxes (spring-day-and-night-same) - is at present in the means 365.24219879 middle sun dayslong. Afterwards thus also the Gregorian calendar is in relation to the astronomical reality somewhat too long, i.e. 0.000301 days (= 26 seconds) per year. That means that after approximately 3320 years the prime acre equinox again in former times occur a whole daybecame. If up to then the Christian annuity is maintained, it would offer itself to leave in all years divisible by 3200 the intercalary day again been void although for that time still the connection of the prime acre equinox at the 21. March desiredbecomes.

The Gregorian calendar has 14 possible yearly calendars - it can begin at each of the seven weekdays and have an intercalary day - and one period of 400 years: After this time do not only repeat themselves the expiration of the intercalary days andthus the daily and monthly payment, but also the associated weekdays. 400 years contain 146097 days, that are exactly 20871 weeks. Thus 71 years with one continue to go after 400 years with the same weekday and in each period give it53. Week.

303 A · 365 d/a + 97 A · 366 d/a = 146097 D
146097 D ÷ 7 d/w = 20871 w = 329 A · 52 w/a + 71 A · 53 w/a
400 A · 12mon/a = 4800 mon

due to this periodicity a certain date (day and month or only day) cannot fall directly frequently on all weekdays. Calculated the 13. any monthly falls more frequently (688mal in 400 years) on one Fridayas on other weekdays (Thursday and Saturday: 684mal, Monday and Tuesday: 685mal, Sunday and Wednesday: 687mal). One month is on the average 30.436875 days or 4.348125 weeks long, i.e. four weeks, two days, ten hours, 29 minutes and six seconds or2.629746 megaseconds (without consideration of switching seconds).

146097 D ÷ 4800 mon = 30.436875 d/mon
20871 w ÷ 4800 mon = 4.348125 w/mon

in the English-language area the additive old Style or O.S. becomes.used, in order to mark that a datethe Julian calendar is meant.New Style or N.S. stands for the Gregorian calendar.

see also

Wikipedia on the left of toGroup of topics calendar and time

Article for the chronology of mankind:
linear units of the time calculation cyclic units of the time calculation
millenium century decade year (calendar) month week day (calendar)
starting from 10. Millenium v. Chr. starting from 40. Century v. Chr. starting from 390er v. Chr. starting from 400 v. Chr. 1. January to 31. December
further articles about time:
An overview of entire geologic history offers the geological time scale.
From the Big Bang to the emergence of the earth see early history of theUniverse.
For the units of time measurement see: Second, minute, hour.

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