Frequently Asked Questions

How were years numbered before the time of Christ?

In many ways. Each nation had its own method of numbering years. Early Romans counted them from the City of Rome’s founding, which corresponds to what we now refer to as 753 B.C. Greeks numbered every four years as one Olympiad, starting with the first Olympic games in 776 B.C. Many other nations started counting years over again with each new ruler, so they would refer to the (n)th year of king whoever. Another widely used method was to count them starting with some important event. For instance, the caliph Omar, who succeeded Mohammed as the leader of Islam, established a year count starting from the time of Mohammed’s migration from Makkah to Medina in A.D. 622.

When did the use of A.D. and B.C. begin?

A.D. is an abbreviation of the term anno Domini, Latin for “in the year of the Lord.” The concept of A.D. is thought to have been first used in the 6th century by Dionysius Exiguus, a monk. This era began with what most people think was the year of Christ’s birth. (Some historians now say that Christ was born from 4 to 7 years earlier.) The term B.C. for “Before Christ” has been in use since the end of the eighteenth century. Neither of these two eras start with a year numbered as zero: 1 B.C. is followed immediately by A.D. 1.
Note that a.d. (in lower case) stands for ante diem, a term once used when naming a day in terms of its relation to either the Calends, Nones or Ides in early Roman calendars. Example: “a.d.VI.Kal.Mar.” referred to the sixth day before the Calends of March.

What were months of September, October, November & December named after?

See the answer to “Why do the 9th thru 12th months have names that mean 7th, 8th, 9th and 10th?” immediately below.

Why does February have only 28 days?

January and February both date from shortly after the time of Rome’s founding. They were added to a calendar that had been divided into ten month-like periods whose lengths varied from 20 to 35 or more days. Those lengths are believed to have been intended to reflect growth stages of crops and cattle. The winter season was not included.
When introduced, January was given 29 days and put at the beginning of the calendar year. February was given 23 days and put at the end. Then, for an undetermined period shortly after Rome’s founding, months were said to have begun when a new moon was first sighted. At some later time, month lengths were separated from lunations and again became fixed. At that time, February’s original length was extended by five days to give it a total of 28. If you would like to read about other nations that also added five days to their calendars close to the same time see my 8th to 4th Century B.C. Calendar Changes.

Did the new millennium begin on January 1 of 2000 or 2001?   

Both! A millennium is any period of one thousand years. One in which all year numbers have a high order (thousands) digit of 2 began with the year 2000 and will end at the close of 2999.
Because the A.D. era’s first year was numbered one, the first thousand years of that millennium ended at the close of year 1000. The next A.D. millennium began with 1001 and ended a thousand years later at the end of 2000. So the third A.D. millennium began at the first moment of 2001.

Will you please tell me (whatever) for my homework?  

If I helped everyone who asked me to provide information for homework I would have time for nothing else. Some time ago I quit responding to all those email requests. (If you are looking for detailed data about Caesar and/or Rome rather than calendars, you should visit both N.S. Gill’s Julius Caesar and Bill Thayer’s RomanSites).

How frequently do dates of a calendar year repeat on the same days of the week?  

In terms of all dates of two calendar years being on corresponding days of the week, identical Gregorian Calendar leap years repeat after every 28 years as long as every fourth one of them includes a 29-day February. Common years are different—they repeat after either six, eleven or 28 years, but these repetitions are broken after a fourth year that is not intercalary. You can check it out using links provided in the following question’s answer.

What formula can be used to associate dates with a day of the week?  

There are several to choose from at Rudy Limeback’s Calendar Links (chlick this link)