Changes

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. 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. 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.

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 at a time when the old calendar was still in force.