Julian Calendar

The Julian Calendar, named after Julius Caesar who instituted it in 45 BC, is the basis of the calendar that we still use today. The calendar is a solar reckoning, with the months bearing no relation to the moon. The months, with their lengths, are as follows.

• January, 31 days
• February, 28 days (29 in leap years)
• March, 31 days
• April, 30 days
• May, 31 days
• June, 30 days
• July, 31 days
• August, 31 days
• September, 30 days
• October, 31 days
• November, 30 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 accomodate 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. 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.

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, 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.