The Gregorian calendar can, for certain purposes, be extended backwards to dates preceding its official introduction, producing the proleptic Gregorian Calendar. However, this proleptic calendar should be used with great caution. For ordinary purposes, the dates of events occurring prior to 15 October 1582 are generally shown as they appeared in the Julian calendar, and not converted into their Gregorian equivalents. However, events occurring in countries where the Gregorian calendar was introduced later than 4 October 1 ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

Read more here: » Gregorian calendar: Encyclopedia II - Gregorian calendar - Proleptic Gregorian calendar

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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This image shows the difference between the Gregorian calendar and the seasons. The Y axis is "days error" and the X axis is Gregorian calendar years. Each point represents a single date on a given year. The error shifts by about 1/4 day per year. Years that are multiples of 100 but not 400 are NOT leap years. This causes a correction on years 1700, 1800, 1900, 2100, 2200, and 2300. For instance, these corrections cause 23 December 1903 to be the latest December solstice, and 20 December 2096 to be the earliest solst ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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The Gregorian calendar is the calendar that is used nearly everywhere in the world. A modification of the Julian calendar, it was first proposed by the Neapolitan doctor Aloysius Lilius, and was decreed by Pope Gregory XIII, for whom it was named, on 24 February 1582 (Note: The papal bull Inter gravissimas was signed in the year 1581 for unknown reasons, but printed on 1 March 1582. Although the use of the date 1581 is often attributed to the supposed adoption by the papacy of a reckoning by which the year began on 25 March, other contemporaneous papal bulls have years that do not agree with March years, let alo ...

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Gregorian calendar - History
Gregorian calendar - Invention Gregorian calendar - Beginning of the year Gregorian calendar - Adoption outside of Roman Catholic nations
Gregorian calendar - Proleptic Gregorian calendar Gregorian calendar - Confusion with British vs. American usage Gregorian calendar - Difference between Gregorian and Julian calendar dates Gregorian calendar - Months of the year Gregorian calendar - Accuracy Gregorian calendar - Calendar seasonal error Gregorian calendar - Numerical facts Gregorian calendar - Number of leap years starting on a given day of the week Gregorian calendar - Days of the week Gregorian calendar - Reference

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August 12 is the 224th day of the year (225th in leap years) in the Gregorian Calendar. There are 141 days remaining. It is the peak of the Perseid meteor shower. It is also known as the "Glorious Twelfth" in the UK, as it marks the traditional start of the grouse shooting season. August 12 - Events. 490 BC - the Battle of Marathon, in which Athens defeated an invasion army of Persians, may have been fought on this date in the proleptic Julian calendar - but see 12 Septe ...

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August 12 - Events August 12 - Births August 12 - Deaths August 12 - Holidays and observations

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Centuries: 1st century BC - 1st century - 2nd century Decades: 40s BC 30s BC 20s BC 10s BC 0s BC - 0s - 10s 20s 30s 40s 50s Years: 1 2 3 4 5 6 7 8 9 Because of the nonexistence of the "year 0", this "decade" and its predecessor have only nine years each. (Year 0 does not exist in either the proleptic Gregorian calendar or Julian calendar) 0s - Events and trends. 0s - Significant people. Caesar Augustus, Roman Emperor (27 BC - 14 AD).Including:

0s - Events and trends 0s - Significant people

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Centuries: 2nd century BC - 1st century BC - 1st century Decades: 50s BC 40s BC 30s BC 20s BC 10s BC - 0s BC - 0s 10s 20s 30s 40s Years: 9 BC 8 BC 7 BC 6 BC 5 BC 4 BC 3 BC 2 BC 1 BC Because of the nonexistence of the "year 0", this "decade" and its successor have only nine years each. (Year 0 does not exist in either the proleptic Gregorian calendar or Julian calendar) 0s BC - Events and trends. circa 4 BC - Jesus is born in Bethlehem. 0 ...

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0s BC - Events and trends 0s BC - Significant people

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Gregorian calendar - Invention. The motivation of the Catholic Church in adjusting the calendar was to have Easter celebrated at the time that they thought had been agreed to at the First Council of Nicaea in 325. Although a canon of the council implies that all churches used the same Easter, they did not. The Church of Alexandria celebrated Easter on the Sunday after the 14th day of the Moon that falls on or after the vernal equinox, which they placed on 21 March. However, the Church of Rome still regarded 25 Ma ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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January 1 of any year whose number is a multiple of 400 is a Saturday. From this you can work out the day of the week of any date. See also: Days of the week Calculating the day of the week ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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Dates of events in Britain prior to 1752 are usually now shown in their original Old Style form, whereas dates of events in (then British) America prior to 1752 are usually now shown in the New Style form. For example, Shakespeare died on 23 April (OS), and it is rare to see this converted to 3 May (NS). But while George Washington was born on 11 February (OS), his birthday is now celebrated on 22 February (N ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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When leap years and common years are taken into account, there are a total of 14 possible Gregorian calendars. When different dates of Easter are also taken into account, there are a total of 70 possible Gregorian calendars. An average year is 365.2425 days = 52.1775 weeks = 8,765.82 hours = 525,949.2 minutes = 31,556,952 seconds. A common year is 365 days = 8,760 hours = 525,600 minutes = 31,536,000 seconds. A leap year is 366 days = 8,784 hours = 527,040 minutes = 31,622,400 seconds. (Some years may also contain one or two leap seconds which can be positive or negative.) See als ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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The Gregorian calendar's year is divided into 12 months: English speakers sometimes remember the number of days in each month by the use of the traditional mnemonic verse: Thirty days hath September / April, June and November / All the rest have thirty-one / Excepting February alone / Which has but twenty-eight, in fine / Till leap year gives it twenty-nine. Alternate endings are: Which has eight and a score / Until leap year gives it one day more, or Which hath twenty-eight days clear / And twenty-nine in each leap year. or When ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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Because there are 97 leap years in every 400 in the Gregorian Calendar, there should, in each "cycle", be either 13 or 14 leap years starting on each day of the week. However, the effects of the "common" centennial years (1700, 1800, 1900, 2100, 2200 etc.) cause major alterations. This is because the absence of an extra day in such years causes the following leap year (1704, 1804, 1904, 2104 etc.) to start on the same day of the week as the leap year twelve years before (1692, 1792, 1892, 2092 etc.). Similarly, the leap year ei ...

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Gregorian calendar, Gregorian calendar - History, Gregorian calendar - Invention, Gregorian calendar - Beginning of the year, Gregorian calendar - Adoption outside of Roman Catholic nations, Gregorian calendar - Proleptic Gregorian calendar, Gregorian calendar - Confusion with British vs. American usage, Gregorian calendar - Difference between Gregorian and Julian calendar dates, Gregorian calendar - Months of the year, Gregorian calendar - Accuracy, Gregorian calendar - Calendar seasonal error, Gregorian calendar - Numerical facts, Gregorian calendar - Number of leap years starting on a given day of the week, Gregorian calendar - Days of the week, Gregorian calendar - Reference

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The ordinary year in the previous Roman calendar consisted of 12 months, for a total of 355 days. In addition, an intercalary month, the Mensis Intercalaris, was sometimes inserted between February and March. This intercalary month was formed by inserting 22 days before the last five days of February, creating a 27-day month. It began after a truncated February having 23 or 24 days, so that it had the effect of adding 22 or 23 days to t ...

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Julian calendar, Julian calendar - From Roman to Julian, Julian calendar - Leap years error, Julian calendar - Naming of the months, Julian calendar - Lengths of the months, Julian calendar - Year numbering, Julian calendar - From Julian to Gregorian

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Despite the new calendar being much simpler than the Roman calendar, the pontifices apparently misunderstood the algorithm. They added a leap day every three years, instead of every four years. According to Macrobius, the error was the result of counting inclusively, so that the four year cycle was considered as including both the first and fourth years. This resulted in too many leap days. Caesar Augustus remedied this discrepancy by restoring the correct frequency after 36 years of this mistake. He also ski ...

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Julian calendar, Julian calendar - From Roman to Julian, Julian calendar - Leap years error, Julian calendar - Naming of the months, Julian calendar - Lengths of the months, Julian calendar - Year numbering, Julian calendar - From Julian to Gregorian

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Hebrew calendar - Epoch. The epoch of the modern Hebrew calendar is 1 Tishri AM 1 (AM = anno mundi = in the year of the world), which in the proleptic Julian calendar is Monday, October 7, 3761 BCE, the equivalent tabular date (same daylight period). This date is about one year before the traditional Jewish date of Creation on 25 Elul AM 1. A minority place Creation on 25 Adar AM 1, six months earlier, or six months after the modern epoch. Thus adding 3760 to any Julian/Gregorian year number after 1 ...

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Hebrew calendar, Hebrew calendar - History, Hebrew calendar - Biblical period, Hebrew calendar - Babylonian exile, Hebrew calendar - Second Temple era, Hebrew calendar - Roman Era, Hebrew calendar - Alexandrian Jewish calendar, Hebrew calendar - Transition period, Hebrew calendar - When does the year begin?, Hebrew calendar - Modern calendar, Hebrew calendar - Epoch, Hebrew calendar - Measurement of the month, Hebrew calendar - Pattern of calendar years, Hebrew calendar - Measurement of hours, Hebrew calendar - Measurement of lunar conjunctions/molads, Hebrew calendar - Metonic cycle, Hebrew calendar - Special holiday rules, Hebrew calendar - Karaite interpretation, Hebrew calendar - Accuracy

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Immediately after the Julian reform, the twelve months of the Roman calendar were named Ianuarius, Februarius, Martius, Aprilis, Maius, Iunius, Quintilis, Sextilis, September, October, November, and December, just as they were before the reform. Their lengths were set to their modern values. The old intercalary month, the Mensis Intercalaris, was abolished and replaced with a single intercalary day at the same point (i.e. five days before the end of Februarius). The first month of the year ...

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Julian calendar, Julian calendar - From Roman to Julian, Julian calendar - Leap years error, Julian calendar - Naming of the months, Julian calendar - Lengths of the months, Julian calendar - Year numbering, Julian calendar - From Julian to Gregorian

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According to the 13th century scholar Sacrobosco, the original scheme for the months in the Julian Calendar was very regular, alternately long and short. From January through December, the month lengths according to Sacrobosco for the Roman Republican calendar were: 30, 29, 30, 29, 30, 29, 30, 29, 30, 29, 30, and 29, totaling 354 days. He then thought that Julius Caesar added one day to every month except February, a total of 11 more days, giving the year 365 days. A leap day could now be added to the extra short February: 31, 2 ...

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Julian calendar, Julian calendar - From Roman to Julian, Julian calendar - Leap years error, Julian calendar - Naming of the months, Julian calendar - Lengths of the months, Julian calendar - Year numbering, Julian calendar - From Julian to Gregorian

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The dominant method that the Romans used to identify a year for dating purposes was to name it after the two consuls who took office in it. Since 153 BC, they had taken office on 1 January, and Julius Caesar did not change the beginning of the year. Thus this consular year was an eponymous or named year. Roman years were named this way until the last consul was appointed in 541. Only rarely did the Romans number the year from the founding of the city (of Rome), ab urbe condita (AUC). This method was used by Roman historians to determi ...

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Julian calendar, Julian calendar - From Roman to Julian, Julian calendar - Leap years error, Julian calendar - Naming of the months, Julian calendar - Lengths of the months, Julian calendar - Year numbering, Julian calendar - From Julian to Gregorian

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The Julian calendar was in general use in Europe from the times of the Roman Empire until 1582, when Pope Gregory XIII promulgated the Gregorian Calendar, which was soon adopted by most Catholic countries. The Protestant countries followed later, and the countries of Eastern Europe even later. Great Britain had Thursday 14 September 1752 follow Wednesday 2 September 1752. Sweden adopted the new style calendar in 1753, but also for a twelve-year period starting in 1700 used a modified Julian Calendar. Russia remained on the Julian calendar un ...

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Julian calendar, Julian calendar - From Roman to Julian, Julian calendar - Leap years error, Julian calendar - Naming of the months, Julian calendar - Lengths of the months, Julian calendar - Year numbering, Julian calendar - From Julian to Gregorian

Read more here: » Julian calendar: Encyclopedia II - Julian calendar - From Julian to Gregorian