The Gregorian Calendar Home Calendar Gregorian The Gregorian Calendar The Gregorian calendar is today's internationally accepted civil calendar and is also known as the Western or Christian calendar. The Vatican, 'birth place' of the Gregorian calendar. Rome's Vatican City is the 'birth place' of the Gregorian calendar, named after Pope Gregory XIII, who introduced it. ©iStockphoto.com/Antonio Gravante Go to Calendar 12 Irregular Months The Gregorian Calendar is the most widely used calendar in the world today. It is a solar calendar based on a 365-day common year divided into 12 months of irregular lengths. 11 of the months have either 30 or 31 days , while the second month, February , has only 28 days during the common year. However, nearly every four years is a leap year , when one extra – or intercalary – day, is added on 29 February , making the leap year in the Gregorian calendar 366 days long. Replaced Julian Calendar The Gregorian calendar's predecessor, the Julian Calendar , was replaced because it was too inaccurate.

It did not properly reflect the actual time it takes the Earth to circle once around the Sun, known as a tropical year . Realigned With the Sun The Julian calendar's formula to calculate leap years produced a leap year every four years. This is too often, and eventually the Julian calendar was several days out of sync with the fixed dates for astronomical events like equinoxes and solstices . The introduction of the Gregorian calendar allowed for the realignment with events like the vernal equinox and winter solstice . New Leap Year Formula The Gregorian calendar was first adopted in Italy, Poland, Portugal and Spain in 1582 , and included the following changes: New formula for calculating leap years: The year is evenly divisible by 4; If the year can be evenly divided by 100, it is NOT a leap year, unless; The year is also evenly divisible by 400: Then it is a leap year 10 days were dropped in October 1582 New rules for calculating Easter -dates Is Any Calendar Perfect? The more advanced leap year formula makes the Gregorian calendar far more accurate than the Julian. However, it is not perfect either.

Compared to the tropical year, it is off by one day every 3236 years. Who Designed the Calendar? Although the Gregorian calendar is named after Pope Gregory XIII, it is an adaptation of a calendar designed by Italian doctor, astronomer and philosopher Luigi Lilio (also known as Aloysius Lilius). He was born around 1510 and died in 1576, six years before his calendar was officially introduced. The Gregorian Calendar—History Religious and Secular Holidays September 2, 1752, was a great day in the history of sleep. That Wednesday evening, millions of British subjects in England and the colonies went peacefully to sleep and did not wake up until twelve days later. Behind this feat of narcoleptic prowess was not some revolutionary hypnotic technique or miraculous pharmaceutical discovered in the West Indies. It was, rather, the British Calendar Act of 1751, which declared the day after Wednesday the second to be Thursday the fourteenth. Prior to that cataleptic September evening, the official British calendar differed from that of continental Europe by eleven days—that is, September 2 in London was September 13 in Paris, Lisbon, and Berlin.

The discrepancy had sprung from Britain's continued use of the Julian calendar, which had been the official calendar of Europe since its invention by Julius Caesar (after whom it was named) in 45 B.C. Caesar's calendar, which consisted of eleven months of 30 or 31 days and a 28-day February (extended to 29 days every fourth year), was actually quite accurate: it erred from the real solar calendar by only 11½ minutes a year. After centuries, though, even a small inaccuracy like this adds up. By the sixteenth century, it had put the Julian calendar behind the solar one by 10 days. In 1582, Pope Gregory XIII ordered the advancement of the calendar by 10 days and introduced a new corrective device to curb further error: century years such as 1700 or 1800 would no longer be counted as leap years, unless they were (like 1600 or 2000) divisible by 400. If somewhat inelegant, this system is undeniably effective, and is still in official use in the United States.

The Gregorian calendar year differs from the solar year by only 26 seconds—accurate enough for most mortals, since this only adds up to one day's difference every 3,323 years. Despite the prudence of Pope Gregory's correction, many Protestant countries, including England, ignored the papal bull. Germany and the Netherlands agreed to adopt the Gregorian calendar in 1698; Russia only accepted it after the revolution of 1918, and Greece waited until 1923 to follow suit. And currently many Orthodox churches still follow the Julian calendar, which now lags 13 days behind the Gregorian. Since their invention, calendars have been used to reckon time in advance, and to fix the occurrence of events like harvests or religious festivals. Why So Difficult? Since their invention, calendars have been used to reckon time in advance, and to fix the occurrence of events like harvests or religious festivals. Ancient peoples tied their calendars to whatever recurring natural phenomena they could most easily observe. In areas with pronounced seasons, annual weather changes usually fixed the calendar; in warmer climates such as Southern Europe, Africa, and the Middle East, the moon was used to mark time.

Unfortunately, the cycles of the sun and moon do not synchronize well. A lunar year (consisting of 12 lunar cycles, or lunations, each 29½ days long) is only 354 days, 8 hours long; a solar year lasts about 365¼ days. After three years, a strict lunar calendar would have diverged from the solar calendar by 33 days, or more than one lunation. The Muslim calendar is hence the only purely lunar calendar in widespread use today. Its months have no permanent connection to the seasons— Muslim religious celebrations, such as Ramadan , may thus occur at any date of the Gregorian calendar. The phases of the moon have nonetheless remained a popular way to divide the solar year, if only because a 365¼-day year doesn't exactly lend itself to equal subdivision (the 71¼-day month has yet to find favor among menologists). To compensate for the difference in the solar and lunar year, calendar makers introduced the practice of intercalation—the addition of extra days or months to the calendar to make it more accurate.

The semilunar Hebrew calendar, consisting of twelve 29- and 30-day months, adds an intercalary month seven times every 19 years (which explains the sometimes confusing drift of Passover —and consequently Easter — through April and March). Despite its widespread use, the Gregorian calendar has a number of weaknesses. It cannot be divided into equal halves or quarters; the number of days per month is haphazard; and months or even years may begin on any day of the week. Best of All Possible Calendars? Despite its widespread use, the Gregorian calendar has a number of weaknesses. It cannot be divided into equal halves or quarters; the number of days per month is haphazard; and months or even years may begin on any day of the week. Holidays pegged to specific dates may also fall on any day of the week, and vanishingly few Americans can predict when Thanksgiving will occur next year. Since Gregory XIII, many other proposals for calendar reform have been made. In the 1840s, philosopher Auguste Comte suggested that the 365th day of each year be a holiday not assigned a day of the week.

The generic "Year Day" would allow January 1 to fall on a Sunday every year. Needless to say, this clever solution was not widely embraced. The French Revolution also saw an attempt at the introduction of a new calendar . On October 5, 1793, the revolutionary convention decreed that the year (starting on September 22, 1792—the autumnal equinox, and the day after the proclamation of the new republic) would be divided into 12 months of 30 days, named after corresponding seasonal phenomena (e.g. seed, blossom, harvest). The remaining five days of the year, called sans-culottides, were feast days. In leap years, the extra day, Revolution Day, was to be added to the end of the year. The Revolutionary calendar had no week; each month was divided into three decades, with every tenth day to be a day of rest. This straightforward calendar, however, perished with the Republic. Did you know? Old Christmas Day and the Lost 11 Days Back to Facts of the Day Calendar UK Calendar dates british festivals .... folklore ... anniversaries .... on this day Old Christmas Day and the Lost 11 Days Did you know?

Nothing whatsoever happened in British history between 3 and 13 September 1752. The Gregorian calendar The Gregorian calendar is the one most used nowadays. It is named after Pope Gregory Xlll who introduced it in 1582. There is a leap year every four years (or more precisely, 97 leap years every 400 years). This means that the year corresponds closely with the astronomical year (365.24219 days) so that it is just one day out every 3,300 years. The Julian Calendar Up until 1753, the calendar we used in Britain was the Julian Calendar. It was based on the solar year, the time it takes for the Earth to rotate around the Sun, and thus was less accurate than the Gregorian Calendar. The Julian Calendar was 365.25 days long, which was fractionally too long, and the calendar over time fell out of line with the seasons. All change - "Give us back our 11 days!" In 1752 Britain decided to correct this by abandoning the Julian calendar in favour of the Gregorian.

By doing so, 3 September instantly became 14 September - and as a result, nothing whatsoever happened in British history between 3 and 13 September 1752. Many people thought that the government had stolen eleven days of their lives. They protested in the streets, demanding "Give us back our 11 days!" All change for Christmas! Before the calendar was changed, England celebrated Christmas on the equivalent of the 6th of January by our modern, Gregorian reckoning. That is why in some people still call the 6th January, Old Christmas Day. 6 January is also known as Epiphany or Twelfth Day nrich.maths.org/164 Also on this day ... 6 January 1066: The coronation of Harold II, as King of England, succeeding Edward the Confessor. He reigned for ten months before he died at the Battle of Hastings. 6 January 1540: Henry VIII married Anne of Cleves at Greenwich Palace, London. How long did they stay married? What number wife was Anne? Find the answers here 6 January 1412: The birth of St Joan of Arc, the Maid of Orléans.

She was a great heroine of French history and believed that she had a divine mission to drive the British from France. She died at the stake after being captured by the Burgundians and sold to the British. 6 January 1540: King Henry VIII married Anne of Cleves, his fourth wife. 6 January 1916: World War I - The British Government introduced conscription, to replace the many thousands killed in the trenches in France. 6 - 7 January 1928: Four people were drowned, and many paintings in the basement of the Tate Gallery were severely damaged, when the Thames flooded. The water was deep enough to fill the moat of the Tower of London. 6 January 1999: Prince Edward & Sophie Rhys-Jones announced their engagement. Links The Missing Eleven Days! Back to Facts of the Day Calendar UK Calendar dates british festivals .... folklore ... anniversaries .... on this day The Missing Eleven Days! Did you know? Nothing whatsoever happened in British history between 3 and 13 September 1752.

The British Calendar Act of 1751 proclaimed that in Britain (and Americn Colonies) Thursday 3 September 1752 should become Thursday 14 September 1752. The Gregorian calendar The Gregorian calendar is the one most used nowadays. It is named after Pope Gregory Xlll who introduced it in 1582. There is a leap year every four years (or more precisely, 97 leap years every 400 years). This means that the year corresponds closely with the astronomical year (365.24219 days) so that it is just one day out every 3,300 years. The Julian Calendar Up until 1753, the calendar we used in Britain was the Julian Calendar. It was 365.25 days long, which was fractionally too long, and the calendar over time fell out of line with the seasons and thus was less accurate than the Gregorian Calendar. All change - "Give us back our 11 days!" In 1752 Britain decided to abandon the Julian calendar in favour of the Gregorian.

By doing so, 3 September instantly became 14 September - and as a result, nothing whatsoever happened in British history between 3 and 13 September 1752. Many people believed their lives would be shortened. They protested in the streets, demanding "Give us back our 11 days!" Also on this day...... 3 September 1939 - WW2 declared British ultimatum to Germany, demanding halt to invasion of Poland (which started on 1 September 1939), expired at 11am, GMT, 3 September 1939. At 11:15 AM, in a radio broadcast, Prime Minister Neville Chamberlain announced the declaration of war against Germany. 3 September - Cromwell Day Oliver Cromwell died on this day in 1658. The day is commemorated with an open air service in front of his statue outside the Houes of Parliament in London. Cromwell was an English military and political leader best known in England for his involvement in making England into a republican Commonwealth and for his later role as Lord Protector of England, Scotland and Ireland.

3 September - Merchant Navy Day The day remembers the 30,000 men of the British Merchant Navy who were lost between 1939-1945. For almost six years during WW2 barely a day went by without the loss of merchant ships and their crews. The Gregorian calendar The Gregorian calendar The Gregorian calendar is the one used in the western world today. ©iStockphoto.com/ pmphoto The Gregorian calendar is today's internationally accepted civil calendar and is also known as the "Western calendar" or "Christian calendar". It was named after the man who first introduced it in February 1582: Pope Gregory XIII. See the Gregorian calendar Calendar features The calendar is strictly a solar calendar based on a 365-day common year divided into 12 months of irregular lengths. Each month consists of either 30 or 31 days with 1 month consisting of 28 days during the common year. A Leap Year usually occurs every 4 years which adds an extra day to make the second month of February 29 days long rather than 28 days.

Realigned with the equinox The Gregorian calendar reformed the Julian calendar because the Julian calendar introduced an error of 1 day every 128 years. The introduction of the Gregorian calendar allowed for the realignment with the equinox, however a number of days had to be dropped when the change was made. The Gregorian calendar was first adopted in Italy, Poland, Portugal and Spain in 1582 . The Gregorian reform consisted of the following changes: 10 days were dropped in October 1582. New rules were set to determine the date of Easter. The rule for calculating Leap Years was changed to include that a year is a Leap Year if: The year is evenly divisible by 4; If the year can be evenly divided by 100, it is NOT a leap year, unless; The year is also evenly divisible by 400. Then it is a leap year. Is there a perfect calendar? February 30 was a real date For example, the years 1900 , 2100 , and 2200 are not Leap Years.

However, the years 1600 , 2000 , and 2400 are Leap Years. The Julian calendar is currently (between the years 1901 and 2099) 13 days behind the Gregorian calendar because too many Leap Years were added. The Gregorian calendar is off by about 1 day every 3236 years. Switching to the Gregorian calendar The Gregorian calendar would not be adopted until much later in Great Britain and America. It wasn’t until September 1752 that 11 days were dropped to switch to the Gregorian calendar. Sweden and Finland had a "double" Leap Year in 1712 . Two days were added to February – creating a date of February 30, 1712 . This was done because the Leap Year in 1700 was dropped and Sweden's calendar was not synchronized with any other calendar. By adding an extra day in 1712, they were back on the Julian calendar. Japan replaced its lunisolar calendar with the Gregorian calendar in January 1873 , but decided to use the numbered months it had originally used rather than the European names.

The Republic of China originally adopted the Gregorian calendar in January 1912 , but it wasn’t used in China due to warlords using different calendars. However, the Nationalist Government formally decreed the adoption of the Gregorian calendar in China in January 1929. Who designed the Gregorian calendar? Although the Gregorian calendar is named after Pope Gregory XIII, it is an adaptation of a calendar designed by Italian doctor, astronomer and philosopher Luigi Lilio (also known as Aloysius Lilius). He was born around 1510 and died in 1576, six years before his calendar was officially introduced. Advertising The Calendar Question The Calendar Question by Andrew Bond Surely, more nonsense has been written about this subject in Orthodox journals than about almost any other ecclesiastical controversy. This year, another jurisdiction, the "Orthodox Church in America," has introduced a change of calendar, so perhaps this is a convenient moment to re-examine the arguments for and against such a change. The official announcement by the OCA merely stated that the New Calendar would be adopted on the Church's New Year Day (1st Sept.) 1982, but gave no actual reasons for this decision.

However, the official newspaper of the OCA, The Orthodox Church, in its February 1982 issue published a lengthy apologia. The gist of the OCA argument seems to be that, although there is only one Julian Calendar, there are four versions of it that have been used at different times. Thus the impression given is that there is no continuous tradition, and that changes to the calendar have taken place before, and that another is, therefore, quite in order. The article is described as a "Memorandum of Explanation by the Holy Synod," and claims that the "data presented are taken from published documents from Constantinople in 1923 and from Moscow in 1948." Let us examine the data cited in this article. The first item is the "Original Julian Calendar," worked out by the astronomer Sosigenes for Julius Caesar and introduced in 44 B.C. There was an inaccuracy in his calculations of about eleven minutes per year, which nobody disputes. Then we come to something called the "Old Style Julian Calendar." Here it is necessary to quote in full: "The 'Old Style' Julian Calendar dates from A.D. 325.

By the fourth century the spring equinox was arriving on March 21st according to the 'Original' Julian Calendar. When the First Ecumenical Council met in Nicea in 325 to settle the date for celebrating Pascha, the Church adopted the 'Original' Julian Calendar and ruled that Pascha shall be observed on the first Sunday, after the first full moon, after the spring equinox on March 21st and independent of the Jewish Passover. The Council did not correct the calendar, nor did it set the spring equinox date back to March 25th where it was in the first place. By fixing a faulty civil calendar date to a fixed phenomenon in nature, the Church created for herself a calendar problem." [Emphasis mine. A.B.] Having told us that the Council adopted the "Original Julian Calendar" and made no changes, what does the next sentence mean? It says, "The 'Old Style' Julian Calendar dates from A. D. 325 and not from the year B.C. 44, as is commonly believed." Clearly from the evidence given, the "Original" and the "Old Style" are one and the same thing!

In any event, this brings us to the question of authority. In the Orthodox Church we accept infallibility, not in a personal, papal sense, but as the voice of Christ's Church expressed through an Ecumenical Council. Thus, even if a change had been made in A. D. 325, which it was not, it would have been quite legitimate and binding on all Christians, simply because it is only an Ecumenical Council that can order these aspects of the Church's liturgical discipline. This is why Pope Gregory in 1582 and Patriarch Meletios in 1923 acted in defiance of Holy Tradition. They did something they had not the right to do, by usurping and taking to themselves the authority that rightly belongs to a General Council. The next exhibit in the OCA article is called the "New Style Julian Calendar," but is actually the Gregorian Adjustment named after Pope Gregory XIII, introduced in 1582 and commonly called the Gregorian Calendar.

The memorandum notes that this adjustment more or less corrects the eleven minute error, and then goes on to tell us about the "Revised Julian Calendar," which has the curious characteristic that "until about the year 2200 both the 'New Style' and the 'Revised' versions of the Julian Calendar will coincide" (!). These are all false and misleading distinctions. There is only one Julian Calendarnot an "Original, "Old Style," "New Style," or "Revised." No amount of invented distinctions and superfluous information can mask these facts: 1) The Julian Calendar has remained unchanged and in continuous use for over two thousand years; 2) The other church calendar is called the "Gregorian Calendar,"not the "New Style Julian Calendar." + + + One claim often made in favor of "calendar reform" is that it would be more convenient to have the festivals, such as Christmas, at the same time as they are celebrated by everyone else. But where was the Gregorian Adjustment first introduced into the Orthodox Church? Not in the diaspora, but in places like Constantinople, Greece and Romania, where almost all the Christians are Orthodox.

When Pope Gregory XIII introduced his adjustment, he tried to pressure the Orthodox Church into doing the same, but a synod which met in 1583 gave him a very firm reply. Carrying the signatures of Patriarch Jeremias II of Constantinople, Patriarch Sylvester of Alexandria and Patriarch Sophronios of Jerusalem, the document states: "Whosoever does not follow the customs of the Church which the Seven Holy Ecumenical Councils have decreed, and the Holy Pascha and calendar which they enacted well for us to follow, but wants to follow the newly invented Paschalion [method of fixing the date of Easter] and the new calendar of the atheist astronomers of the Pope; and, opposing the Councils, wishes to overthrow and destroy the doctrines and customs of the Church, which we have inherited from our Fathers, let any such have the anathema and let him be outside the Church and the Assembly of the Faithful." A very different spirit prevailed in 1923, when an "Inter-Orthodox Congress" was called together by Patriarch Meletios of Constantinople.

Its agenda also included proposals to allow bishops to be married and to allow a priest to remarry after the death of his first wife. The congress was attended by delegates from Constantinople, Greece, Cyprus, Serbia (which rejected the calendar change) and Romania. The Patriarchs of Antioch and Jerusalem refused to send delegates, the Patriarch of Alexandria did not reply to the invitation and the Church of Bulgaria was not invited. In the diaspora, a certain tension can exist in a mixed marriage, where there may be pressure on the Orthodox partner to conform to the local custom at a time like Christmas. However, domestic convenience is not the criterion for determining liturgical discipline. Every Christmas time in the West there are heard numerous religious voices lamenting the fact that Christmas is so commercialized. We who are Orthodox do not have a commercialized Christmas because we celebrate it on a day that the world around us regards as an ordinary working day. Why give up this advantage? In this respect, the Jewish community sets us an example. They are deeply involved in commerce in Europe, America and elsewhere, but they have not changed the dates of their festivals to coincide with secular holidays, although doubtless their businesses would profit by doing so.

The desire for astronomical accuracy is just a red herring. If it really were an important consideration, surely the advocates of the Gregorian Adjustment would use the Gregorian reckoning for everything, including Easter. By not doing so, they seek to avoid the condemnation of the First Canon of the Synod of Antioch (A.D. 341) which says that if any bishop, priest or deacon disturbs the good order of the Church by "observing Easter (at the same time) with the Jews, the holy Synod decrees that he shall henceforth be an alien from the Church, as one who not only heaps sins upon himself, but who is also the cause of destruction and subversion to many; and it deposes not only such persons themselves from their ministry, but those also who after their deposition shall presume to communicate with them." No room for doubt there about the attitude of the Church to those who celebrate Easter at the same time as the Passover; yet, think how often the Latin West does just that. But in seeking to avoid this transgression, the Orthodox Christians who use the Gregorian Calendar fall into another trap by celebrating Easter sometimes in May, which is also also forbidden.

It is indeed fortunate that the liturgical order of the Church does not depend on astronomical accuracy. Far more important to us is the unbroken unity of the Church. This has several aspects, of which the unbroken cycle of liturgical prayer is one. By dropping thirteen days in making the Gregorian Adjustment, we break this continuous liturgical cycle and thus violently disrupt the unity of the Church, by which we are at one with all our fellow Orthodox believers now and through the centuries. Which is preferable: unity of prayer with the saints and all Orthodox Christians or, by adjusting the liturgical cycle, unity with Pope Gregory and the Latin/Protestant West? The OCA memorandum concludes: "If the Orthodox Church is the Pillar of Truth, it cannot afford to ignore the scientific truths discovered by man. How can we claim: I believe in One God, the Father Almighty, Creator of heaven and earth.... and refuse to accept the truth of the scientific measurements of the length of the year he created?" Yes, the Orthodox Church is the Pillar of Truth, and for this very reason, we must defend the decisions of the Seven Ecumenical Councils as God's revealed and timeless Truth. Scientific truth is much more unreliable.

That everything is,composed of four elements, that the sun revolves around the earth, that the earth is flat, and many other things have, in their time, been regarded as scientific truth, but our saving faith has never depended on such "truths. " Make no mistake, the line of reasoning that advocates the adoption of the Gregorian Adjustment will open the flood gates to other and more serious innovations. The Queen of Feasts, Easter, is already under attack. Already, some Orthodox hierarchs are suggesting that we do not really have any objections to a fixed day for Easter, and that we could fall into line with the suggestion of the Pope and the World Council of Churches on this issue. Sadly, some simple souls will be led into believing that this is true, when in reality any such suggestion is utterly condemned by numerous canons. This whole insidious process leads the faithful, often in trusting naively, further and further away from the Ark of Salvation. First, break the liturgical cycle of the fixed-date festivals, and then settle a fixed date for Easter, all in the name of a spurious unity with those who deny Orthodoxy.

Having detached most of the faithful from any true understanding of Holy Tradition and the nature of the Church, it will be quite a short step to destroy a principle of worship that has always characterized the religion of the True God. This is the seven-day or weekly cycle of prayer. Throughout the time of the Old Covenant, as God Himself commanded Moses, every seventh day was a day of prayer. When almost everything else relating to the Old Covenant was superseded by Christ, the resurrection guaranteed that the seven-day cycle of worship would continue unbroken. This also could soon be under threat by the introduction of the "World-wide Calendar." This anti-Christian abomination has been accepted, in principle, by the governments of the world. The only thing they cannot agree upon is when and how to introduce it. Its basic premise is that commerce would be able to plan production schedules more effectively if all holidays were at the same time each year. In other words, the plan guarantees that Christmas Day would always be a Sunday and New Year's Eve, a Saturday. The odd day each year (a year is 52 weeks and one day long) would be disposed of by adding "World Day" at the end of December.

So the sequence would be "Saturday," December 31; followed by "World Day;" followed by "Sunday,"January 1. In a Leap Year, a second "World Day" would be inserted between the last day of June and the first day of July. In this calendar the day designated as "Sunday" could actually be any day of the week, and the seven day cycle of worship would be disrupted every year, and twice every Leap Year. Doubtless, the Latin/Protestant West will regard this as being of no importance and accept the change with alacrity, when it comes. If the Orthodox Christians who presently use the Gregorian Adjustment continue to do so, their domestic convenience will again be shattered. They will have unity with nobody, neither with their fellow Orthodox nor with the West and the modern world. From The Orthodox Word, Sep.-Oct., 1982, vol. 32, no. 5, 45-48.

6 Things You May Not Know About the Gregorian Calendar - History in the Headlines 6 Things You May Not Know About the Gregorian Calendar September 13, 2012 By Jennie Cohen William Hogarth’s painting “An Election Entertainment,” thought to have sparked rumors that English citizens rioted after the adoption of the Gregorian calendar. Share this: 6 Things You May Not Know About the Gregorian Calendar Author 6 Things You May Not Know About the Gregorian Calendar URL Google If you were living in England or one of the American colonies 260 years ago, this date—September 13, 1752—didn’t exist. Neither did the 10 days preceding it. Instead, you would have gone to bed on the evening of September 2 and woken up on the morning of September 14. Eleven days had been effectively skipped over as part of the parliamentary measure that implemented the Gregorian calendar, aligning Britain and its overseas possessions with the rest of Western Europe. In most of the world today, people continue to track their days, months and years using the centuries-old system, so chances are you’re intimately familiar with its workings.

Still, there are a few things about the Gregorian calendar that might come as a surprise. 1. The original goal of the Gregorian calendar was to change the date of Easter. In 1582, when Pope Gregory XIII introduced his Gregorian calendar, Europe adhered to the Julian calendar, first implemented by Julius Caesar in 46 B.C. Since the Roman emperor’s system miscalculated the length of the solar year by 11 minutes, the calendar had since fallen out of sync with the seasons. This concerned Gregory because it meant that Easter, traditionally observed on March 21, fell further away from the spring equinox with each passing year. 2. Leap years don’t really occur every four years in the Gregorian calendar. The Julian calendar included an extra day in February every four years. But Aloysus Lilius, the Italian scientist who developed the system Pope Gregory would unveil in 1582, realized that the addition of so many days made the calendar slightly too long. He devised a variation that adds leap days in years divisible by four, unless the year is also divisible by 100. If the year is also divisible by 400, a leap day is added regardless.

While this formula may sound confusing, it did resolve the lag created by Caesar’s earlier scheme—almost. 3. The Gregorian calendar differs from the solar year by 26 seconds per year. Despite Lilius’ ingenious method for syncing the calendar with the seasons, his system is still off by 26 seconds. As a result, in the years since Gregory introduced his calendar in 1582, a discrepancy of several hours has arisen. By the year 4909, the Gregorian calendar will be a full day ahead of the solar year. 4. Some Protestants viewed the Gregorian calendar as a Catholic plot. Though Pope Gregory’s papal bull reforming the calendar had no power beyond the Catholic Church, Catholic countries—including Spain, Portugal and Italy—swiftly adopted the new system for their civil affairs. European Protestants, however, largely rejected the change because of its ties to the papacy, fearing it was an attempt to silence their movement. It wasn’t until 1700 that Protestant Germany switched over, and England held out until 1752. Orthodox countries clung to the Julian calendar until even later, and their national churches have never embraced Gregory’s reforms. 5.

Britain’s adoption of the Gregorian calendar sparked riots and protest—maybe. According to some accounts, English citizens did not react kindly after an act of Parliament advanced the calendar overnight from September 2 to September 14, 1752. Rioters supposedly took to the streets, demanding that the government “give us our 11 days.” However, most historians now believe that these protests never occurred or were greatly exaggerated. On the other side of the Atlantic, meanwhile, Benjamin Franklin welcomed the change, writing, “It is pleasant for an old man to be able to go to bed on September 2, and not have to get up until September 14.” 6. Before the Gregorian calendar’s adoption, the English new year began on March 25, or Lady Day. Julius Caesar’s calendar reform of 46 B.C. instituted January 1 as the first of the year. During the Middle Ages, however, European countries replaced it with days that carried greater religious significance, such as December 25 (the anniversary of Jesus’ birth) and March 25 (the Feast of the Annunciation).

The latter, known as Lady Day because it celebrates the Virgin Mary, marked the beginning of the year in Britain until January 1, 1752. Tags Gregorian - Dictionary definition of Gregorian | Encyclopedia.com: FREE online dictionary Gregorian The Oxford Dictionary of Phrase and Fable © The Oxford Dictionary of Phrase and Fable 2006, originally published by Oxford University Press 2006. Gregorian of or pertaining to someone named Gregory. Gregorian calendar the calendar introduced in 1582 by Pope Gregory XIII, as a modification of the Julian calendar. To bring the calendar back into line with the solar year, 10 days were suppressed, and centenary years were only made leap years if they were divisible by 400. Scotland adopted the Gregorian calendar in 1600, but England and Wales did not follow suit until 1752 (by which time 11 days had to be suppressed). At the same time New Year's Day was changed from 25 March to 1 January, and dates using the new calendar were designated ‘New Style’.

Gregorian chant church music sung as a single vocal line in free rhythm and a restricted scale (plainsong), in a style developed for the medieval Latin liturgy, and named after St Gregory the Great, who is said to have standardized it. Cite this article Pick a style below, and copy the text for your bibliography. MLA Gregorian calendar | Calendar Wiki | Fandom powered by Wikia Edit The Gregorian solar calendar is an arithmetical calendar. It counts days as the basic unit of time, grouping them into years of 365 or 366 days. The solar calendar repeats completely every 146,097 days, which fill 400 years, and which also happens to be 20871 seven-day weeks . Of these 400 years, 303 (the "common years") have 365 days, and 97 - the leap years - have 366 days. This gives an average year length of exactly 365.2425 days - or 365 days, 5 hours, 49 minutes and 12 seconds.

A Gregorian year is divided into twelve months of irregular length (but note that there is a period of 153 days divided over 5 months in an alternating pattern from March to July that repeats from August to December): No. December 31 A calendar date is fully specified by the year (numbered by some scheme beyond the scope of the calendar itself), the month (identified by name or number), and the day of the month (numbered sequentially starting at 1). Leap years are all years divisible by 4, with the exception of those divisible by 100, but not by 400. These 366-day years add a 29th day to February, which normally has 28 days. Thus, the essential ongoing differential feature of the Gregorian calendar, as opposed to the Julian calendar, is that the Gregorian omits 3 leap days every 400 years. This difference would have been more noticeable in modern memory, were it not for the fact that the year 2000 was a leap year in both the Julian and Gregorian calendar systems. The intercalary day in a leap year is known as a leap day .

Since Roman times February 24 ( bissextile ) was counted as the leap day (month), but nowadays February 29 is regarded as the leap day in most countries. Although the calendar year runs from January 1 to December 31 , sometimes year numbers were based on a different starting point within the calendar. Confusingly, the term "Anno Domini" is not specific on this point, and actually refers to a family of year numbering systems with different starting points for the years. (See the section below for more on this issue.) History Edit The motivation of the Catholic Church in adjusting the calendar was to celebrate Easter at the time they thought was 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 (computed using the Metonic cycle) that falls on or after the vernal equinox, which they placed on March 21,. However, the Church of Rome still regarded March 25, as the equinox and used a different cycle to compute the day of the Moon.

By the tenth century all churches (except for some on the eastern border of the Byzantine Empire) had adopted the Alexandrian Easter, which still placed the vernal equinox on March 21,, although Bede had already noted its drift in 725—it had drifted even further by the sixteenth century. Worse, the reckoned Moon that was used to compute Easter was fixed to the Julian year by a 19 year cycle. However, that approximation built up an error of one day every 310 years, so by the sixteenth century the lunar calendar was out of phase with the real Moon by four days. for a more consistent and accurate scheduling of the feast of Easter. The fix was to come in two stages. First, it was necessary to approximate the correct length of a solar year. The value in the major astronomical tables of the day.

Although close to the mean tropical year of 365.24219 days, it is even closer to the vernal equinox year of 365.2424 days; this fact made the choice of approximation particularly appropriate as the purpose of creating the calendar was to ensure that the vernal equinox would be near a specific date (March 21). (See Accuracy). The second stage was to devise a model based on the approximation which would provide an accurate yet simple, rule-based calendar. The formula designed by Aloysius Lilius was ultimately successful. It proposed a 10-day correction to revert the drift since Nicaea, and the imposition of a leap day in only 97 years in 400 rather than in 1 year in 4. To implement the model, it was provided that years divisible by 100 would be leap years only if they were divisible by 400 as well.

So, 2000 and 2400 are leap years, but 1700, 1800, 1900, 2100, 2200 and 2300 are non-leap years. This theory was expanded upon by Christopher Clavius in a closely argued, 800 page volume. He would later defend his and Lilius's work against detractors. The 19-year cycle used for the lunar calendar was also to be corrected by one day every 300 or 400 years (8 times in 2500 years) along with corrections for the years (1700, 1800, 1900, 2100, 2200, 2300, 2500, etc.) that are no longer leap years. In fact, a new method for computing the date of Easter was introduced.

Lilius originally proposed that the 10-day correction should be implemented by deleting the Julian leap day on each of its ten occurrences during a period of 40 years, thereby providing for a gradual return of the equinox to March 21,. However, Clavius's opinion was that the correction should take place in one move and it was this advice which prevailed with Gregory. Accordingly, when the new calendar was put in use, the error accumulated in the 13 centuries since the Council of Nicaea was corrected by a deletion of ten days. The last day of the Julian calendar was Thursday October 4, 1582 and this was followed by the first day of the Gregorian calendar, Friday October 15, 1582 (the cycle of weekdays was not affected). Nevertheless, the dates "October 5, 1582" to "October 14, 1582" (inclusive) are still valid in virtually all countries because most non-Catholic countries initially rejected the reform and even most Catholic countries did not adopt the new calendar on the date specified by the bull but only with some delay.

Adaptation Edit Only Spain and her territories, Portugal, the Polish-Lithuanian Commonwealth, and most of Italy implemented the new calendar on Friday, October 15, 1582, following Julian Thursday, October 4, 1582. France adopted the new calendar on Monday, December 20, 1582, following Sunday, December 9, 1582.[1] The Protestant Dutch provinces of Holland and Zeeland also adopted it in December of that year. Most non-Catholic countries initially objected to adopting a Catholic invention. Although Scotland changed the beginning of the year to January 1, in the year 1600, like England and thereby the rest of the British Empire (including the eastern part of what is now the United States), Scotland did not adopt the Gregorian calendar until 1752; by which time it was necessary to correct by eleven days (Wednesday, September 2, 1752 being followed by Thursday, September 14, 1752) to account for February 29, 1700 (Julian).

A few years later, when the son of the Earl of Macclesfield (who had been influential in passing the calendar law) ran for a seat in Parliament in Oxfordshire as a Whig in 1754, dissatisfaction with the calendar reforms was one of a number of issues raised by his Tory opponents. In 1755, William Hogarth made a painting (and an engraved print from the painting) loosely based on these elections, in which the campaign slogan "Give us our Eleven Days" appears (on floor at lower right); this was later misunderstood, giving rise to apocryphal stories of widespread riots at the change-over. Great Britain legislated special provisions to make sure that monthly or yearly payments would not become due until the dates that they originally would have in the Julian calendar. From 1753 until 1799, the tax year in Great Britain began on April 5,, which was the "old style" new year of March 25,. A 12th skipped Julian leap day in 1800 changed its start to April 6,.

It was not changed when a 13th Julian leap day was skipped in 1900, so the tax year in the United Kingdom is still April 6,. "Old Style" (OS) and "New Style" (NS) are sometimes added to dates to identify which system is used in the British Empire and other countries that did not immediately change. In Britain it is usual to map most dates from the Julian year onto the Gregorian year without converting the day and month. But because the start of the year did not change until the same year that the Gregorian calendar was introduced, OS/NS is particularly relevant for dates which fall between January 1, and March 25,.

For example the execution of King Charles I is usually recorded as having taken place on January 30, 1649 (NS), but in contemporary documents it is recorded as having taken place on January 30, 1648.[2] Denmark, Norway and the Protestant states of Germany adopted the solar portion of the new calendar on Monday, March 1, 1700,[3], following Sunday, February 18, 1700, due to the influence of Ole Rømer, but did not adopt the lunar portion. Instead, they decided to calculate the date of Easter astronomically using the instant of the vernal equinox and the full moon according to Kepler's Rudolphine Tables of 1627. They finally adopted the lunar portion of the Gregorian calendar in 1776. The remaining provinces of the Dutch Republic also adopted the Gregorian calendar in 1700. Sweden's relationship with the Gregorian Calendar had a difficult birth.

Sweden started to make the change from the OS calendar and towards the NS calendar in 1700, but it was decided to make the (then 11 day) adjustment gradually, by excluding the leap days (February 29,) from each of 11 successive leap years, 1700 to 1740. In the meantime, not only would the Swedish calendar be out of step with both the Julian calendar and the Gregorian calendar for 40 years, but also the difference would not be static but would change every 4 years. This strange system clearly had great potential for endless confusion when working out the dates of Swedish events in this 40 year period. To make matters worse, the system was poorly administered and the leap days that should have been excluded from 1704 and 1708 were not excluded. The Swedish calendar should by now have been 8 days behind the Gregorian, but it was still in fact 10 days behind. King Charles XII wisely recognised that the gradual change to the new system was not working and he abandoned it.

However, rather than now proceeding directly to the Gregorian calendar (as in hindsight seems to have been the sensible and obvious thing to do), it was decided to revert to the Julian calendar. This was achieved by introducing the unique date February 30, in the year 1712, adjusting the discrepancy in the calendars from 10 back to 11 days. Sweden finally adopted the Gregorian calendar in 1753, when Wednesday, February 17, was followed by Thursday, March 1,.[4] In Alaska, the change took place when Friday, October 6, 1867 was followed again by Friday, October 18 after the US purchase of Alaska from Russia, which was still on the Julian calendar. Instead of 12 days, only 11 were skipped, and the day of the week was repeated on successive days, because the International Date Line was shifted from east of to west of Alaska along with the change to the Gregorian calendar. In Russia the Gregorian calendar was accepted after the October Revolution (so named because it took place in October 1917 in the Julian calendar).

On January 24, 1918 the Council of People's Commissars decreed that Wednesday, January 31, 1918 was to be followed by Thursday, February 14, 1918. The last country of Eastern Orthodox Europe to adopt the Gregorian calendar was Greece on Thursday, March 1, 1923, following Wednesday, February 15, 1923. However, these were all civil adoptions—none of the national churches accepted it. Instead, a Revised Julian calendar was proposed in May 1923 which dropped 13 days in 1923 and adopted a different leap year rule that resulted in no difference between the two calendars until 2800. The Orthodox churches of Constantinople, Alexandria, Antioch, Greece, Cyprus, Romania, Poland, and Bulgaria adopted the Revised Julian calendar, so these New calendarists will celebrate the Nativity along with the Western churches on December 25, in the Gregorian calendar until 2800. The Orthodox churches of Jerusalem, Russia, Serbia, Georgia and the Greek Old Calendarists did not accept the Revised Julian calendar.

These Old Calendarists continue to celebrate the Nativity on December 25, in the Julian calendar, which is January 7, in the Gregorian calendar until 2100. All of the other Eastern churches, the Oriental Orthodox churches (Coptic, Ethiopian, Eritrean, Syrian, Armenian) and the Assyrian Church, continue to use their own calendars, which usually result in fixed dates being celebrated in accordance with the Julian calendar. All Eastern churches continue to use the Julian Easter with the sole exception of the Finnish Orthodox Church, which has adopted the Gregorian Easter. Adoption in East Asia Edit The Republic of China (ROC) formally adopted the Gregorian calendar at its founding on January 1, 1912, but China soon descended into a period of warlordism with different warlords using different calendars. With the unification of China under the Kuomintang in October 1928, the Nationalist Government decreed that effective January 1, 1929 the Gregorian calendar would be used henceforth.

However, China retained the Chinese traditions of numbering the months and a modified Era System, backdating the first year of the ROC to 1912; this system is still in use in Taiwan where this ROC government retains control. Upon its foundation in 1949, the People's Republic of China continued to use the Gregorian calendar with numbered months, but abolished the ROC Era System and adopted the Western fashion of naming years. Japan replaced the traditional lunisolar calendar with the Gregorian calendar on January 1, 1873, but, like China, continued to number the months, and used reign names instead of the Common Era: Meiji 1=1868, Taisho 1=1912, Showa 1=1926, Heisei 1=1989, and so on. The "Western calendar" (西暦, seireki) using western year numbers, is also widely accepted by civilians and to a lesser extent by government agencies. Korea started using the Gregorian calendar on January 1, 1896 due to Japanese influence.

The lunisolar Korean calendar used immediately before that day was based on the lunisolar Chinese calendar . Proleptic Gregorian calendar Edit 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 October 15, 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 October 4, 1582 are a little more contentious. For example, in Great Britain and its overseas possessions (then including the American colonies), the new calendar was not introduced until September 14, 1752. How, then, would people date events occurring in Britain and her possessions in the 170 years between 1582 and 1752? The answer depends very much on the context, but writers who want to avoid confusion make it absolutely clear which calendar is being used.

People have avoided changing historical records in Britain deriving from this period; however, it is often highly desirable to translate particular Old Style dates into their New Style equivalents, such as where the context includes reference to other countries that had already converted to New Style before Britain did. Astronomers avoid this ambiguity by the use of the Julian day number. If comparisons of dates are done using different calendars, we can encounter logical absurdities such as William and Mary of Orange seeming to arrive in London to accept the English crown, a week or so before they left the Netherlands; and Shakespeare and Cervantes apparently dying on exactly the same date (April 23, 1616), when in fact Cervantes predeceased Shakespeare by 10 days in real time. This coincidence however has allowed UNESCO to make April 23 the World Book and Copyright Day. For dates before the year 1, unlike the proleptic Gregorian calendar used in the international standard ISO 8601, the traditional proleptic Gregorian calendar (like the Julian calendar) does not have a year 0 and instead uses the ordinal numbers 1, 2, ..., both for years AD and BC and for CE and BCE.

Thus the traditional timeline is 2 BC, 1 BC, AD 1, and AD 2. ISO 8601 uses astronomical year numbering which includes a year 0 and negative numbers before it. Thus the ISO 8601 timeline is -0001, 0000, 0001, and 0002. Confusion with British versus American usage Edit 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 April 23, (OS), and it is rare to see this converted to May 3, (NS). But while George Washington was born on February 11, (OS), his birthday is now celebrated on February 22, (NS), even though he himself continued to celebrate his birthday on February 11.

However, neither of these practices is universal in either country, so it is sometimes very unclear which calendar is being used, and this can lead to false assumptions, which can lead to dates being inaccurately converted from one calendar to the other. Since the resurgence of interest in the history of the calendar, more information about the real dates (according to various calendars) of events has been forthcoming and many previous errors have been corrected. While these changes are welcome, there is still much scope for confusion; specifically noting the calendar being used can help the reader understand the dates involved. Months of the year English speakers sometimes remember the number of days in each month by the use of the traditional mnemonic verse: [1] Thirty days hath September, February alone don't hold the line, for three years it has twenty-eight, and the fourth year twenty-nine. but February, it is done at twenty-eight, but add one more whenever the year divides by four. A shorter, satirical modern alternate ending is: but silly old February spoils the fun. A language-independent alternative used in many countries is to hold up your two fists with the index knuckle of your left hand against the index knuckle of your right hand.

Then, starting with January from the little knuckle of your left hand, count knuckle, space, knuckle, space through the months. A knuckle represents a month of 31 days, and a space represents a short month (a 28- or 29-day February or any 30-day month). The junction between the hands is not counted, so the two index knuckles represent July and August. This method also works by starting the sequence on the right hand's little knuckle, and continue toward to the left. You can also use just one hand; after counting the fourth knuckle as July, start again counting the first knuckle as August.

The Origins of English naming used by the Gregorian calendar: January: Janus (Roman god of gates, doorways, beginnings and endings) February: Februus] (Etruscan god of death) Februarius (mensis) (Latin for "month of purification (rituals)" it is said to be a Sabine word, the last month of ancient pre-450 BC Roman calendar) March: Mars (Roman god of war) April: Aprilis (mensis) (Latin for "month of Venus," second month of ancient Roman calendar) May: Maia Maiestas (Roman goddess) June: Juno (Roman goddess, wife of Jupiter) July: Julius Caesar] (Roman dictator) August: Augustus (first Roman emperor) September: septem (Latin for seven, the seventh month in the calendar of Romulus and Remus|Romulus) October: octo (Latin for eight, the eighth month in the calendar of Romulus) November: novem (Latin for nine, the ninth month in the calendar of Romulus) December: decem (Latin for ten, the tenth month in the calendar of Romulus) Accuracy Edit The Gregorian calendar improves the approximation made by the Julian calendar

 by skipping three Julian leap days in every 400 years, giving an average year of 365.2425 mean solar days long, which has an error of about one day per 3300 years with respect to the mean tropical year of 365.24219 days but less than half this error with respect to the vernal equinox year of 365.24237 days.

Both are substantially more accurate than the one day in 128 years error of the Julian calendar (average year 365.25 days). In the 19th century, Sir John Herschel proposed a modification to the Gregorian calendar with 969 leap days per 4000 years, instead of 97 leap days per 400 years, thus reducing the average year to 365.24225 days. However, Herschel's proposal was never accepted. On timescales of thousands of years, the Gregorian calendar falls behind the seasons drastically because the slowing down of the Earth's rotation makes each day slightly longer over time (see tidal acceleration and leap second ) while the year maintains a more uniform duration. The equinox will occur earlier than now by a number of days approximately equal to [years into future/5000]2. This is a problem that the Gregorian calendar shares with any fixed rule-based calendar. Numerical facts Edit When leap years and common years are taken into account, there are a total of 14 possible Gregorian calendars.

When the five different weeks in which Easter can fall are also taken into account, there are a total of 70 possible Gregorian calendars. The 70 possible Gregorian calendars have a wide range of frequency of occurrence. The commonest Gregorian calendar is a common year starting on Thursday with Easter in week 5 (April 19) which occurs in 2.93% of all years, or once every 34.1 years on average. This year layout last occurred in 1987 and will next occur in 2071. The rarest year layout is a leap year starting on Wednesday with Easter in week 1 (March 22) which occurs in 0.117% of all years, or on average once every 857 years. This year layout has never occurred since 1583, the first Easter after the Gregorian reform in 1582. It will occur for the first time in 2972, assuming the Gregorian calendar is not reformed before then.

An average year is 365.2425 days = 52.1775 weeks = 8,765.82 hours = 525,949.2 minutes = 31,556,952 seconds. All these numbers are exact, apart from leap 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. Since 1971, some years may also contain one or more leap seconds, to account for cumulative irregularities in the Earth's rotation. So far, these have always been positive and have occurred on average once every 18 months.

The day of the year is somewhat inconvenient to compute, not in the least because of the leap day somewhere in the middle; but the calendar has this repeating pattern for the months March through July and August through December: 31, 30, 31, 30, 31 days, totalling 153 days. In fact, any 5 consecutive months not containing February, count 153 days. 153 happens to be the 17th triangular number, and the sum of the first 5 factorials (among other numerical trivia). The 400-year cycle of the Gregorian calendar has 146,097 days and hence exactly 20,871 weeks. So, for example, the days of the week in Gregorian 1603 were exactly the same as for 2003. This also causes more months to begin on a Sunday (and hence have Friday 13) than any other day of the week (see below for a more detailed explanation of how this happens).

688 out of every 4800 months (or 172/1200) begin on a Sunday, while only 684 out of every 4800 months (171/1200) begin on each of Saturday and Monday, the least common cases. A smaller cycle is 28 years (1,461 weeks), provided that there is no dropped leap year in between. Days of the week in years may also repeat after 6, 11, 12, 28 or 40 years. Intervals of 6 and 11 are only possible with common years, while intervals of 28 and 40 are only possible with leap years. An interval of 12 years only occurs with common years when there is a dropped leap year in between. The Doomsday algorithm is a method by which you can discern which of the 14 calendar variations should be used in any given year (after the Gregorian reformation). It is based on the last day in February, referred to as the Doomsday.

The Gregorian serial date, also called Rata Die, is the number of days from January 1, 1 A.D. (counting that day as day 1). For January 31, 2007, the serial date is 732707. It is 678576 more than the Modified Julian date, and 1721425 less than the Julian date 2454132. Week Edit In conjunction with the system of months there is a system of weeks. A physical or electronic calendar provides conversion from a given date to the weekday, and shows multiple dates for a given weekday and month. Calculating the day of the week is not very simple, because of the irregularities in the Gregorian system. The ISO week date connects Gregorian years and weeks, defining a leap week calendar with so-called "ISO years" deviating at the beginning and end up to 3 days from Gregorian years, and with week numbers by year.

Origins of English naming used by the Gregorian Calendar: Sunday - sun day (celestial) Tuesday - Tyr's day (Old Norse god - Tiw in Old English, Teiw in Proto-Germanic) Wednesday - Woden's day (Old English god - Norse Odin, German Wotan)) Thursday - Thor's day (Old Norse god) Friday - Frigg's day (Old Norse goddess) (Friday is often erroneously associated with Freyja) Saturday - Saturn's day (Roman god) Distribution of dates by day of the week Edit Because there are 97 leap years in every 400 years in the Gregorian Calendar, there are on average 136⁄7 for each starting weekday in each cycle. This already shows that the frequency is not the same for each weekday, which is due to the effects of the "common" centennial years (1700, 1800, 1900, 2100, 2200 etc.).

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 eight years after a "common" centennial year (1708, 1808, 1908, 2108 etc.) starts on the same day of the week as the leap year immediately prior to the "common" centennial year (1696, 1796, 1896, 2096 etc.). Thus, those days of the week on which such leap years begin gain an extra year or two in each cycle.

In each cycle there are: 13 leap years starting on Monday 14 leap years starting on Tuesday 14 leap years starting on Wednesday 13 leap years starting on Thursday 15 leap years starting on Friday 13 leap years starting on Saturday 15 leap years starting on Sunday Note that as a cycle, this pattern is symmetric with respect to the low Saturday value. A leap year starting on Sunday means the next year does not start on Monday, so more leap years starting on Sunday means fewer years starting on Monday, etc. Thus the pattern of number of years starting on each day is inverted and shifted by one weekday: 56, 58, 57, 57, 58, 56, 58 (symmetric with respect to the high Sunday value). The number of common years starting on each day is found by subtraction: 43, 44, 43, 44, 43, 43, 43. The frequency of a particular date being on a particular weekday can easily be derived from the above (for dates in March and later, relate them to the next New Year). See also the cycle of Doomsdays.

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. Trivia Edit The Roman calendar was modified by Julius Caesar when he occupied the office of Pontifex Maximus and the Julian calendar was subsequently modified by Gregory XIII, who, as pope, also held the title Pontifex Maximus. Non-leap years always begin and end on the same day of the week, since 364 (365 - 1) is a multiple of 7, the number of days in a week. For example, 2003 began on a Wednesday and ended on a Wednesday. Leap years end on the next day of the week from which they begin. For example, 2004 began on a Thursday and ended on a Friday. Not counting leap years, any calendar date will move to the next day of the week the following year. For example, if your birthday fell on a Tuesday in 2002, it fell on a Wednesday in 2003. Leap years make things a little more complicated.

2004 was a leap year, so calendar days of March 1 or later in the year, moved two days of the week from 2003. However, calendar days occurring before March 1 do not make the extra day of the week jump until the year following a leap year. So, if your birthday is June 15, then it must have fallen on a Sunday in 2003 and a Tuesday in 2004. If, however, your birthday is February 15, then it must have fallen on a Saturday in 2003, a Sunday in 2004 and a Tuesday in 2005. In any year (even a leap year), July always begins on the same day of the week that April does. Therefore, the only difference between a July calendar page and an April calendar page in the same year is the extra day July has. The same relationship exists between September and December as well as between March and November. Add an extra day to the September page and you've got December. Take a day away from the March page and you've got November.

In non-leap years only, there are additional matches: October duplicates January, and March and November duplicate February in their first 28 days. In leap years only, there is a different set of additional matches: July is a duplicate of January while February is duplicated in the first 29 days of August. Saint Teresa of Ávila died on the night from October 4, to October 15, 1582, that is, exactly when Spain and the Catholic world switched to the Gregorian calendar. References

Question: The Gregorian Calendar, introduced in 1582, is named after Gregory, a?
Answer: Pope