How did they know it was BC before Christ was born?
We come to the annual Christmas query, sent in this year by the Managing Editor himself, Billy Sheahan. To wit: "Speaking of Christ, how in the name of Christ did they know what year it was before 0 BC? How did they know when it was 10 BC?" Hardy Har, Billy. If you imagine that there was some toga-laden Casey Kasem, keeping track of the King of Kings Kountdown, it’s time to put a lock on your room. From the outside.
Peter Meyer’s marvelous website about the Julian and the Gregorian Calendars, explains that, "The system of numbering years AD (for Anno Domini, "in the year of Our Lord") was instituted in the year 525 by the Roman abbot Dionysus Exiguus, and endured for more than a millennium. Because of its specifically Christian meaning this designation is now often replaced by the more neutral C.E. (for Common Era), and BC is now often written B.C.E. (for Before Common Era)."
Meyers also explains that, "Originally the Romans numbered years ab urbe condita, that is, "from the founding of the city" (of Rome)…Had this old calendar remained in use, 1996-01-14 would have been New Years Day in the year 2749 a.u.c"
Julius Caesar, recognizing that the a.u.c. calendar of his time was woefully inaccurate, consulted with an Alexandrian astronomer named Sosigenes and established a solar calendar of twelve months and 365 days, with an extra day every fourth year. Rome was almost two hundred years behind the Alexandrians in recognizing the inadequacy of the lunar calendar, but what the hey! All it took was one year that was sixty-seven days longer than normal, and wham, the beginning of March turned into January 1 of the Julian Calendar. This process started in what we now know as the year 46 B.C.E. At that time, however, the Romans were in the year 709 a.u.c. This suggests that 10 B.C.E., the year mentioned in Billy’s question, was perceived by contemporaries as 745 a.u.c.
Man oh Manichewitz, I’m think I’m ready to adopt Dan Akroyd’s metric week!