Calendar era

From Academic Kids

A calendar era is the year numbering system used by a calendar. For example, the Gregorian calendar numbers its years in the Western Christian era (the Coptic and Ethiopic churches have their own Christian eras, see below). The instant, date, or year from which time is marked is called the epoch of the era. There are many different calendar eras. Some are listed below along with their abbreviations (if any).

  • A.D. (or AD) — for the Latin Anno Domini, meaning in the year of the Lord. Years are counted from the beginning of the dominant or Western Christian Era. AD is used in the Gregorian calendar. The years are equivalent to years in the Common Era (CE).
    • Note: AD was also used in the medieval Julian Calendar as well, but the calendars are not identical. To distinguish between them, O.S. and N.S. were often added to the date, especially during the 17th and 18th centuries, when both calendars were in common use. O.S. or Old Style was used for the Julian calendar. N.S. or New Style was used for the Gregorian calendar.
  • C.E. (or CE) — meaning Common Era, which is used with the Gregorian calendar and coincides exactly with the Christian Era.
  • A.C., B.C. (or BC), and B.C.E. (or BCE) — for the Latin Ante Christum, the English Before Christ, and Before the Common Era, respectively. In all cases, years count backward from the year AD 1 or, equivalently, 1 CE. Note that there is no year 0 in the Julian or Gregorian calendars, but there is in astronomical year numbering, as well as in the Hindu and Buddhist calendars.
  • A.U.C. (or AUC) — for the Latin Ab Urbe Condita, meaning from the founding of the city (of Rome). The first day of its year was Founder's Day (April 21), although most modern historians assume that it coincides with the modern historical year (January 1 to December 31). It was rarely used in the Roman calendar and in the early Julian calendar — naming the two consuls that held office in a particular year was dominant. Dionysius Exiguus implied, but did not explicitly state, that AD 1 was 754 AUC, so that the year 2005 is the same as the year 2758 AUC (2005 + 753).
  • A.M. (or AM) — for the Latin Anno Mundi, meaning in the year of the world. This is used in the Hebrew calendar which counts years from the creation of the world, which is assumed to have taken place in the year 3761 BC. AM was also used for all first millennium world eras of the early Christian chronographers. Related to this are the Anno Lucis of Freemasonry, which adds 4000 years to the AD date, and the Aetos Kosmou of the Byzantine Greek Calendar (in which the year 7514 begins in September 2005 AD), both of which claim to date from Creation.
  • A.M. (or AM) — from the Latin Anno Martyrum (in the year of the martyrs). Used in the Coptic calendar, which counts from 284 CE.
  • A.H. (or AH) — for the Latinized Anno Hegirae, meaning in the year of the Hijra, Prophet Muhammad's migration from Mecca to Medina in September 622, which is taken to be the beginning of the Muslim era. This is used in the Islamic calendar. (Note that, since the Islamic calendar is a lunar calendar, years are shorter than years in solar calendars.)
  • B.E. — for the Bahá'í Era beginning 21 March AD 1844. See Bahá'í calendar for more details.
  • B.E. — for the Buddhist Era, which has an epoch (origin) of 545 BC, but with an offset of one year from this zero year the difference BE − AD is 543 in Thailand.
  • B.P. — for Before Present, specifically, the number of radiocarbon years before 1950, used in radiocarbon dating.
  • Era of Martyrs — used by the Coptic Church. Its epoch is August 29/30, AD 284 in the Julian calendar.
  • Incarnation Era — used by Ethiopia. Its epoch is August 29/30, 8 in the Julian calendar.
  • Japanese eras began with the ascension of an emperor. The most recent eras are:
  • Chinese eras or Nian Hao were traditionally counted from the ascension of an emperor, or the beginning of a new reign title. This practice has been discontinued in the People's Republic of China.
    • The Republic of China continues to count years starting with the founding of the republic in 1912, which is regarded as year one. So 2004 is the 93rd year of the Republican Era.
    • A small number of Chinese use a continuous count of years from the reign of the legendary Yellow Emperor, with different sources using the epochs 2637 BC, 2697 BC, or 2698 BC. See Chinese calendar for more information.
  • The Republican Era of the French Republican Calendar was dated from 22 September 1792, the day of the proclamation of the French First Republic.
  • The Seleucid Era, formerly used in much of the Middle East, uses the epoch 312 BC, the year when Seleucus I Nicator captured Babylon and began his reign over the Asian portions of Alexander the Great's empire.

See also

nl:Jaartelling pl:Era kalendarzowa sl:koledarska doba


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