Changes

*December, 31 days

*December, 31 days

Julius Caesar had held the office of [[Pontifex Maximus]] in Rome since 60 BC. One of the duties of this office was the regulation of the Roman calendar. The old [[Roman]] calendar was a complicated system that attempted to accommodate both a solar and lunar reckoning, but required regular adjustment and during the civil wars of the mid first century BC fell into complete disarray, with months occuring some 90 days before they were supposed to in seasonal terms. Julius Caesar employed an Egyptian astrologer named [[Soseniges]] to devise a completely new system, and although the old Roman month names were retained, most of them had extra days added. Soseniges, who had a good notion of the true length of the year (which was actually a few seconds longer in those days than it is now), calculated that an extra day should be added every four years because he believed that a full year lasted 365¼ days. After Caesar was assassinated in 44 BC, the Romans mistakenly added a leap year every three years insttead of every four, but the Emperor [[Augustus]] corrected this mistake and from 1 AD the calendar ran smoothly.

Julius Caesar had held the office of [[Pontifex Maximus]] in Rome since 60 BC. One of the duties of this office was the regulation of the Roman calendar. The old [[Roman]] calendar was a complicated system that attempted to accommodate both a solar and lunar reckoning, but required regular adjustment and during the civil wars of the mid first century BC fell into complete disarray, with months occuring some 90 days before they were supposed to in seasonal terms. Julius Caesar employed an Egyptian astrologer named [[Soseniges]] to devise a completely new system, and although the old Roman month names were retained, most of them had extra days added. Soseniges, who had a good notion of the true length of the year (which was actually a few seconds longer in those days than it is now), calculated that an extra day should be added every four years because he believed that a full year lasted 365¼ days. After Caesar was assassinated in 44 BC, the Romans mistakenly added a leap year every three years instead of every four, but the Emperor [[Augustus]] corrected this mistake and from 1 AD the calendar ran smoothly.

By the [[Middle Ages]] it had become apparent that the calendar was not precisely accurate. Caesar had arranged it so that the winter solstice occurred on December 25, the traditional date of the rebirth of the sun, but by the 16th century AD it was falling around December 11. This had happened because in reality a year lasts slightly less than 365¼ days and so leap years need to occur slightly less often than once every four years in order for the solstice to remain at a constant point in the calendar.  Pope [[Gregory XIII]], in his capacity as Pontifex Maximus (which the popes had inherited from the Roman emperors after the fall of the Roman Empire), instituted a change, and this revised calendar is known as the [[Gregorian Calendar]]. First of all, ten days were removed from the year 1582, bringing the winter solstice to December 21 (not quite where it was in Caesar's time), and then it was decreed that leap years should be dropped from every year ending in double zero, unless it was also divisible by 400. So, 1600 and 2000 were leap years, but 1700, 1800, and 1900 were not.

By the [[Middle Ages]] it had become apparent that the calendar was not precisely accurate. Caesar had arranged it so that the winter solstice occurred on December 25, the traditional date of the rebirth of the sun, but by the 16th century AD it was falling around December 11. This had happened because in reality a year lasts slightly less than 365¼ days and so leap years need to occur slightly less often than once every four years in order for the solstice to remain at a constant point in the calendar.  Pope [[Gregory XIII]], in his capacity as Pontifex Maximus (which the popes had inherited from the Roman emperors after the fall of the Roman Empire), instituted a change, and this revised calendar is known as the [[Gregorian Calendar]]. First of all, ten days were removed from the year 1582, bringing the winter solstice to December 21 (not quite where it was in Caesar's time), and then it was decreed that leap years should be dropped from every year ending in double zero, unless it was also divisible by 400. So, 1600 and 2000 were leap years, but 1700, 1800, and 1900 were not.

In 1582, however, the pope's writ no longer ran all over Europe, because of the [[Reformation]]. Protestant countries were very slow to adopt this new papal calendar, and [[Great Britain]] and its colonies did not adopt the new calendar until 1752, by which time the difference between the two calendars had risen to eleven days. The Act of Parliament that instituted the new calendar stipulated that all birthdays should be expressed on the new calendar. This is why, for example, that [[George Washington]]'s birthday is celebrated on February 22, when he was actually born on February 11 {{fact}} at a time when the old calendar was still in force.

In 1582, however, the pope's writ no longer ran all over Europe, because of the [[Reformation]]. [[Protestant]] countries were very slow to adopt this new papal calendar, and [[Great Britain]] and its colonies did not adopt the new calendar until 1752, by which time the difference between the two calendars had risen to eleven days. The Act of Parliament that instituted the new calendar stipulated that all birthdays should be expressed on the new calendar. This is why, for example, that [[George Washington]]'s birthday is celebrated on February 22, when he was actually born on February 11 {{fact}} at a time when the old calendar was still in force.

==See also==

==See also==

*[[Mayan calendar]]

*[[Mayan calendar]]

*[[Chinese calendar]]

*[[Chinese calendar]]