Epoch (chronology)

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Under epoch ( Greek Εποχή within the meaning of dt. Breakpoint ) is in the chronology of a new beginning of the era in each era understood.


The time of the epoch is usually a single day (epoch day ) that reflects a historical or fictional event, e.g. B. the beginning of a royal rule, the foundation of a city or the creation of the world. Only modern time systems also specify the time of the epoch.

The individual calendar systems deal with dates before their epoch in different ways: calendars that have calculated since the assumed creation of the world were initially not proleptic , that is, they knew no dates before the epoch. In the Gregorian calendar , the dates of the proleptic Julian calendar are used: Before January 1, 1 AD, this is December 31, 1 BC. Chr. In principle, based on epochs all dynastic calendar systems that start a new year count at the start of a new ruler or dynasty.

A calendar can be used with different epochs. For example, North Korea has a different era than most other countries that use the Gregorian calendar. Conversely, an epoch and the associated era can also be used by different calendars (such as Anno Hegirae ). There are also eras with several possible epochs. An example of this is ab origine mundi . It counts from the presumed creation of the world, which was dated to different points in time. An epoch can also apply to several eras. The North Korean Juche and Taiwanese Minguo calendars, for example, refer to different events, but have identical dates , since both events took place in 1912 AD.

Some epochs in chronological order

In addition to important epochs of historical chronology and the calendar , some epochs of astronomical chronology are also included, and in particular the Julian date JD, which provides the basis for converting the calendar systems, as well as contemporary dating epochs in data processing. In addition, the astronomical year count , which has some special features (e.g. year zero , sign) is shown.

Calendar eruptions

(dates BC)
Astronomical year count JD
Era / epoch Calendar / time system event
January 17, 998038 −998037 Years after the art Julian calendar , Gregorian calendar fictional first birthday of art set by the French artist Robert Filliou in 1963 AD (1,000,000 years before 1963)
January 1, 10000 0−9999 Holocene era / human era Holocene Calendar , Davidian Martian Calendar Approximate beginning of the Holocene
September 1, 5508 0−5507 .−290.130 Byzantine era
Annus Mundi
Julian calendar Creation of the world according to the genealogy of the Greek Bible Septuagint
January 1, 4713 0−4712 0.000.000 Julian day count chronological Julian date Beginning of the Julian period
January 1, 4000 0−3999 0.260.424 Anno Lucis Julian / Gregorian calendar Creation of the world according to the Masonic tradition
October 7, 3761 0−3760 0.347.998 Jewish era Anno Mundi Jewish calendar Creation of the world according to the Mosaic tradition
September 6, 3114 0−3113 0.584.283 Long count Mayan Calendar According to the Thompson correlation
January 1, 2333 0−2332 0.869.315 Dangun era Korean lunisolar calendar, Julian / Gregorian calendar Founding of Go-Joseon and Pyongyang on October 3rd, 2333 BC Chr .; used in South Korea from 1945 to 1961
March 21, 1738 0−1737 1,086,698 Zarathustra era Zoroastrian calendar Legendary birth of Zoroaster
January 1, 1166 0−1165 1,295,542 "Years of Our Lady of Discord " Discordian calendar Synchronization of the Discordian year with the founding year of Discordianism (1959 AD) through consistent application of the Law of Five (1959 - 5 5 = −1166)
July 1, 0776 00−775 1,438,171 Olympic era some greek calendars 1. Olympic Games
April 21, 0753 00−752 1,446,501 Varronic era Roman calendar ,
Julian calendar
Founding of the city of Rome , from the urbe condita counting
April 21, 0752 00−751 1,446,866 Catonian / Capitoline count
February 26, 0747 00−746 1,448,638 Nabonassar era Egyptian change year The Babylonian king Nabû-naṣir takes office
February 11, 0660 00−659 1,480,400 Jimmu era Gregorian calendar , Kōki Japanese forging of an empire
January 1, 0544 00−543 1,522,728 Buddhist calendar various calendars, e.g. B. Gregorian calendar, Chinese calendar , Thai lunar calendar , Suriyakati calendar or Tibetan calendar presumed year of death of Siddhartha Gautama
April 3, 0311 00−310 1,607,923 Seleucid era Macedonian calendar Conquest of Babylon by Seleucus I.
January 1, 3800 000−37 1,707,544 Spanish era era Julian calendar unknown event, presumably the subjugation of Spain by the Romans; according to Isidore of Seville, however, a census by the emperor Augustus
January 1st000 0000± 0 1,721,058 Cassini chronology Julian / Gregorian calendar Year zero according to ISO 8601 and the astronomical year count
(dates AD)
Astronomical year count JD
Era / epoch Calendar / time system event
0January 1st000 0000+1 1,721,424 Christian calendar
Anno Domini / Anno Salutis
Julian calendar,
Gregorian calendar
Birth of christ
29 August 8000 0000+8 1,724,221 Ethiopian calendar
August 29, 2840 00+284 1,825,030 Diocletian era ,
era of martyrs
Julian calendar,
Coptic calendar
Diocletian becomes emperor; under his rule the last persecutions of Christians take place
July 11, 5520 00+552 1,922,868 Old Armenian era Armenian calendar Foundation of the Armenian Apostolic Church
March 1, 6220 00+622 1,948,303 hijri shamsi (sun hijra) Rumi calendar Hijra
March 19, 6220 1,948,321 Iranian calendar
July 16, 0622 1,948,440 hijri qamari (moon hijra) Islamic calendar
June 16, 6320 00+632 1,952,063 Yazdgard era Zoroastrian calendar Accession to the throne of Yazdegerd III.
January 28, 1611 0+1611 2,309,493 Mars Daric year Darian calendar Development of Kepler's laws by Johannes Kepler and first observations of Mars with the help of a telescope by Galileo Galilei
January 1,  1789 0+1789 2,374,480 Années de la liberté Positivist Calendar , French Revolution Calendar Storming of the Bastille on July 14, 1789
September 22,  1792 0+1792 2,375,840 Années de la République Française French revolutionary calendar Proclamation of the First French Republic
March 21, 1844 0+1844 2,394,647 Badiʿ Era or Baha'i Era (B. E.) Baha'i Calendar Establishment of Babism in Shiraz (Iran) by the Bab (Seyyed ʿAli Muhammad Schirazi); the Baha'i later emerged from the Babitum
January 1, 1912 0+1912 2,419,403 Minguo era Gregorian calendar Xinhai Revolution
Chuch'e era Year of birth of Kim Il-sung
October 29, 1922 0+1922 2,423,357 Era fascista Mussolini is sworn in as President of the Council of Ministers after the march on Rome
January 1, 1950 0+1950 2,433,283 Before Present (cannot be converted directly into calendar years) Timescale for dating past events with dates from radiocarbon dating
1st May 2019 0+2019 2,447,535 Reiwa time Gregorian calendar Accession of the Tennō Naruhito , current era of the dynastic system of Japan
*While the astronomical Julian date counts the time since January 1st −4712 (4713 BC) 12 noon in days and fractions of days, only the integer day number (chronological Julian date) is required for the chronology. The 1st of January −4712 has the day number 0.

Time-accurate epochs

(dates BC)
Astronomical year count JD
Era / epoch Calendar / time system event
January 1, 4713
12:00:00  TT
−4712 Julian day count Julian date Beginning of the Julian period
(dates AD)
Astronomical year count JD
Era / epoch Calendar / time system event
January 1, 1601 +1601 2,305,824.0 Windows era Microsoft Windows time Start of time counting in Windows operating systems; was chosen because this date marks the start of the first 400 year cycle of the Gregorian calendar .
November 17,  1858
00:00:00 UT
+1 858 2,400,000.5 Era of MJD Modified Julian date  
January 1, 1970
00:00:00  UTC
+1970 2,440,587.5 UNIX epoch Unix time Beginning of Unix time counting (from UNIX version 6) - internal date widely used today in computer systems
January 6, 1980
00:00:00 UTC
+1980 2,444,243.5 GPS week 0 GPS time scale Beginning of the GPS time system
*The astronomical Julian date counts the time in days and fractions of days that has passed since 12 noon on January 1st −4712 (4713 BC). For time specifications that are precise to the second or even more precise, a time scale must also be specified . Without such an indication, the terrestrial time TT is meant in astronomy .

See also


  • Andreas Kamp: From Paleolithic to Postmodern - The genesis of our epoch system. Vol. I: From the beginning to the end of the 17th century. Amsterdam / Philadelphia 2010, ISBN 978-90-272-8736-6 .

Web links

  • Heinrich's homepage calendar converter , website with calendar converter (Julian & Gregorian calendar, Jewish calendar, Islamic calendar, French revolution calendar, Julian date)
  • Calendar calculator by Nikolaus A. Bär: conversion between dates of several ancient and modern calendars (Occident, Middle East, Iran) with output of JD for 12 o'clock; can also be run offline

Individual evidence

  1. Duden: The dictionary of origin. Etymology of the German language. Mannheim 2007, Lemma epoch.
  2. Why is the Win32 epoch January 1, 1601?