Re: Why do Oracle dates go only up to 4712 A.D. is there some technical reason for such a specific date

The Julian day number system is sometimes (erroneously) said to have been invented by Joseph Justus Scaliger (born 1540-08-05 J in Agen, France, died

     1609-01-21 J in Leiden, Holland), who during his life immersed himself in Greek, Latin, Persian and Jewish literature, and who was one of the founders of the

     science of chronology. Scaliger's invention was not the system of Julian days, but rather the so-called Julian period.

     Scaliger combined three traditionally recognized temporal cycles of 28, 19 and 15 years to obtain a great cycle, the Scaliger cycle, or Julian period, of

     7980 years (7980 is the least common multiple of 28, 19 and 15). According to the Encyclopedia Brittanica:

          "The length of 7,980 years was chosen as the product of 28 times 19 times 15; these, respectively, are the numbers of years in the so-called

          solar cycle of the Julian calendar in which dates recur on the same days of the week; the lunar or Metonic cycle, after which the phases of the

          Moon recur on a particular day in the solar year, or year of the seasons; and the cycle of indiction, originally a schedule of periodic taxes or

          government requisitions in ancient Rome."

     According to some accounts Scaliger named his Julian period after his father, Julius Scaliger. However in his De Emandatione Temporum (Geneva, 1629)

     Scaliger says: "Julianam vocauimus, quia ad annum Julianum accommodata ..." (translated by R. L. Reese et al. (3) as "We have termed it Julian because it

     fits the Julian year ...").

     Regarding the Julian period the U.S. Naval Observatory has this to say:

          "In the 16th century Joseph Justus Scaliger tried to resolve the patchwork of historical eras by placing everything on a single system. Not being

          ready to deal with negative year counts, he sought an initial epoch in advance of any historical record. His approach was numerological and

          utilized three calendrical cycles: the 28-year solar cycle, the 19-year cycle of Golden Numbers, and the 15-year indiction cycle. The solar cycle

          is the period after which week days and calendar dates repeat in the Julian calendar. The cycle of Golden Numbers is the period after which

          moon phases repeat (approximately) on the same calendar dates. The indiction cycle was a Roman tax cycle of unknown origin. Therefore,

          Scaliger could characterize a year by the combination of numbers (S,G,I), where S runs from 1 through 28, G from 1 through 19, and I from 1

          through 15. Scaliger first stated that a given combination would recur after 7980 (= 28 x 19 x 15) years. He called this a Julian cycle because it

          was based on the Julian calendar. Scaliger knew that the year of Christ's birth (as determined by Dionysius Exiguus) was characterized by the

          number 9 of the solar cycle, by Golden Number 1, and by number 3 of the indiction cycle, or (9,1,3). Then Scaliger chose as this initial epoch

          the year characterized by (1,1,1) and determined that (9,1,3) was year 4713 of his chronological era [and thus that year (1,1,1) was 4713 B.C].

          Scaliger's initial epoch was later to be adopted as the initial epoch for the Julian day numbers." — The 21st Century and the 3rd Millennium

     It turns out, however, that the Julian period was discovered by others before Scaliger. Roger, Bishop of Hereford, discusses the three cycles used by Scaliger

     in his Compotus (written in 1176 CE) and states that "these three ... do not come together at one point for 7980 years" (see (5)), although he does not

     identify the year (4713 B.C.) of their coincidence. Furthermore, according to R. L. Reese et al. (6):

          "A 12th-century manuscript indicates that the 7980-year period was used explicitly for calendrical purposes by an earlier Bishop of Hereford,

          Robert de Losinga, in the year A.D. 1086, almost a century before the Bishop of Hereford named Roger. ... Robert de Losinga combines the

          solar, lunar and indiction cycles into a "great cycle [magnum ciclum]" of 7980 years ... Thus the manuscript by Robert de Losinga places the

          earliest known use of the Julian period in the year A.D. 1086."

     The first Julian period began with Year 1 on -4712-01-01 (Julian) and will end after 7980 years on 3267-12-31 (Julian), which is 3268-01-22 (Gregorian).

     3268-01-01 J is the first day of Year 1 of the next Julian period Cheers,

        Fred

RyuO wrote:
>
> Actually, in 8.1.5 the date limitation was changed to +- 9999. In any
> earlier release it is +- 4712.
>
> I think the reason for the change is to give Oracle Consulting enough
> time to finish some government projects :)
>
> In article <38398C06.B680B340_at_mahindrabt.com>,
> Deepak Surana <dsurana_at_mahindrabt.com> wrote:
> > the limit is 9999 not 4712 (must be a documentation bug ?)
> >
> > mosene wrote:
> >
> > > why 4712 and not something else?
> >
> > --
> > Deepak Surana, BT Plc.
> > Direct : + 44-181-5876433 GMT
> > e-mail : deepak.surana_at_bt.com
> >
> >
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.

Received on Thu Nov 25 1999 - 06:36:38 CST