Year zero

the year zero does not give it in the Christian calendar and thus also in our present time calculation .

The Roman numbers do not have a symbol for the zero, the so-called Arabic numerals however already. The latters became toward end of the 5. Century in India develops and thus about at the same time to Dionysius Exiguus, which calculated the beginning of the Christian era in the year 525 for the year 754 after the establishment of Rome, the alleged year of the birth Christi. It lastedbut about five centuries (cf. Gerbert of Aurillac ), until one took knowledge in Europe of the “concept of the number zero” at all - and only in the Renaissance the Arabic numerals in Europe found general acknowledgment, spreading and use.

Thereforethere is no year in the time calculation of the historians zero. That has the consequence that between that 1. June 500 v. Chr. and that 1. June 500 n. Chr. surprisingly only 999 years lie. This arithmetically precarious result arranged those Astronomer 18. Century to an own, modified time calculation. (Cf. Epoch jump.)

with Cassini is itself the modern science today in the fact united that a correct chronology actually requires a yearly zero. In the antique chronicles the ruler years became however traditional,e.g. the Caesaren counted, using ordinal numbers. Thus the years of the Christian era justify, the years after Christ - logically correct without year zero - evenly also the “Christian chronicle”. The years before Christ, the “chronicle of the pre-ChristianTime ". Both together result in however no chronology, but two separate chronicles.

Two different years zero were so far defined and suggested. At present however only the “Julian leap year zero” is actually used.

the Julian leap year zero (= 1 v. Chr.)

the astronomers count since 1740 on one Leap year zero (= 1 v. Chr.), whose definition is generally assigned to Jacques Cassini; but might some decades in former times its colleague Philippe de la Hire in its astronomical boards with one year zero have counted. Now one had a chronology, also its name earns, with a logically compelling year zero. This astronomical chronology is “ kalendarisch unkorrekt” nevertheless. First of all it defines the year zero as a leap year, secondly counts it for the time before that 15. October 1582 in Julian years, but after that 4. October 1582 in Gregorian data (cf. of Mädler). Thus an astronomical calendar mistake comes off , which can achieve a whole month for the far past, and plus nevertheless minus one day for thoserecent past and the near future.

comparative table to the Cassini chronology

the traditional historical time calculation corresponds to the Roman calendar of Christian time calculation, however despite missing year the Arab number system uses zero. The traditional astronomical chronology possesses this year zero. ThatYear 1 v. Chr. the year corresponds to 753 since the establishment of Rome.

Note:The above-mentioned tableshows the theoretical, correctly used Julian calendar. Caesar led its new calendar at the 1. January DCC.IX a.u.c. (709 = 45 v. Chr. ). This year was equal one leap year. The year before is called Verworrenes year(because it had 445 days). After Caesars death, was used however 36 years long a wrong, misunderstood switching mode. The year 709 a.u.c. equal again as a first year was understood and inserted in the “fourth” year 712 again one leap year, thus alreadyafter three years. Like that the Roman years were 715, 718, 721 etc. to including 745 a.u.c. (IX v. Chr.) all actually leap years. 36/3 = 12, but 36/4 = 9.
The year 745 would be also with correctly used switching rules Roman leap yearbeen. The actual leap years 749 a.u.c. (= V v. Chr.), 753 a.u.c. (= I v. Chr.) and 757 a.u.c. (= IV n. Chr.) fell however out were thus common years - around the calendar to correct.

Further should still consideredit becomes that, although the New Year of Caesar clearly on the 1. January was specified, dates like “pridie Kal. Ian. “with the following year differently to be interpreted, there the Romans can do 14 starting from that. Decembers backwards counted (XIX Kal ante. Ian.). That30. December is the third [sic] day before the Calenden, the 31. December the Vortag (pridie Kal. Ian.) the Calenden of the coming new yearly is.

the Gregorian leap year zero (≈ 1 v. Chr.)

onedisputed definition created the international standard organization with its standard ISO 8601: 1988, taken over 1992 of the EN 28,601. This world-wide valid, but - at least in this part - also world-wide ignored standard offizialisiert a “proleptischen (retroactively valid) GregorianCalendar ", to which it assigns one leap year zero. This year zero begins at the 3. January 1 forwards and ends to 2. January 1 after Christ. The actual Gregorian calendar does not understand itself however, contrary to the Julian ones, as expressly proleptisch.
Also from the year 2000 one year zero and annual details with minus sign plans the ISO 8601 in the version .

criticism of the standard ISO 8601

• for astronomers is unfavorable the Gregorian 400-Jahre-Zyklus, within its centuries unequal lengths have. Astronomical computations need a homogeneous timing, why astronomers count today first and always in Julian centuries (see Julian date JD) and only at the end of the computations all data after that 4. October 1582 into Gregorian datecorrect. They will also in the future hardly use therefore the standard ISO 8601 = EN 28,601.

• The science of history never used the Julian year zero. It uses the long-known, proleptischen, Julian calendar of the Christian era for this time, thus withoutYear zero. Thus it is also not to be expected that the historians convert the ISO standard 8601 ever. A Umdatierung of all historical events, according to which about Gaius Julius Caesar instead of to 15. March 44 v. Chr. now suddenly at the 1 3. March of the yearly -4 3 (in ISO way of writing: -0043-03-13) was murdered, only welfareless confusion would donate.

• In the computer range formats of date are always converted regarding a certain time. Today that is mostly the 1. January 1970, 00H00 UTC (see Unixzeit). Therefore also computer science does not have need at a “proleptischen Gregorian calendar with one year zero”.

see also:

Yearly calendar: 1. Jhdt. v. Chr. & 1. Jhdt. n. Chr.
Decades: 0er years v. Chr. & 0er years n. Chr.
Years: Year 1 v. Chr. & year 1 n. Chr.

• Epoch jump - annuity at the zero point of the chronology
• turn of an era - selecting points of the chronology
• fence stake problem - to general problems with points of zero
• calendars:
  • Christian time calculation
  • Julian calendar
  • calendar (Roman realm)