Era
An era is a span of time defined for the purposes of
Comparable terms are
Etymology
The word has been in use in English since 1615,[4] and is derived from Late Latin aera "an era or epoch from which time is reckoned," probably identical to Latin æra "counters used for calculation," plural of æs "brass, money".[5][6]
The Latin word use in chronology seems to have begun in 5th century Visigothic Spain, where it appears in the History of Isidore of Seville,[7] and in later texts. The Spanish era is calculated from 38 BC, Before Christ,[8][9] perhaps because of a tax (cfr. indiction) levied in that year, or due to a miscalculation of the Battle of Actium, which occurred in 31 BC.[10]
Like epoch, "era" in English originally meant "the starting point of an age"; the meaning "system of chronological notation" is c. 1646; that of "historical period" is 1741.[11]
Use in chronology
In
Geological era
In large-scale natural science, there is need for another time perspective, independent from human activity, and indeed spanning a far longer period (mainly prehistoric), where "
Era[16][17] | Beginning (millions of years BP) | End (millions of years BP) |
---|---|---|
Cenozoic | 66.038 | N/A |
Mesozoic | 252.17 | 66.038 |
Paleozoic | 542 | 252.17 |
The older Proterozoic and Archean eons are also divided into eras.[18][19]
Cosmological era
For periods in the
Calendar eras
Calendar eras count the years since a particular date (epoch), often one with religious significance.
The
For a time ranging from 1872 to the Second World War, the Japanese used the imperial year system (kōki),[27] counting from the year when the legendary Emperor Jimmu founded Japan, which occurred in 660 BC.[28]
Many
Other calendar eras of the past counted from political events, such as the Seleucid era[30] and the Ancient Roman ab urbe condita ("AUC"), counting from the foundation of the city.[31]
Regnal eras
The word era also denotes the units used under a different, more arbitrary system where time is not represented as an endless continuum with a single reference year, but each unit starts counting from one again as if time starts again.
In East Asia, each emperor's reign may be subdivided into several reign periods, each being treated as a new era.[33] The name of each was a motto or slogan chosen by the emperor. Different East Asian countries utilized slightly different systems, notably:
A similar practice survived in the United Kingdom until quite recently, but only for formal official writings: in daily life the ordinary year A.D. has been used for a long time, but
Historiography
"Era" can be used to refer to well-defined periods in historiography, such as the
Use of the term for more recent periods or topical history might includeSee also
- Periodization
- List of time periods
- List of archaeological periods
- Epoch – Reference point from which time is measured
References
- ^ "Era | definition in the Cambridge English Dictionary". Cambridge Dictionary. Retrieved 11 December 2023.
- ^ "Thesaurus.com - The world's favorite online thesaurus!". Thesaurus.com. 6 December 2023. Retrieved 11 December 2023.
- ^ "Yuga". Dictionary.com Unabridged (Online). n.d. Retrieved 11 December 2023.
- ^ "Time Traveler by Merriam-Webster: Words from 1615". www.merriam-webster.com. Retrieved 11 December 2023.
- ^ Peón, Baltasar (1863). Estudios de cronología universal (in Spanish). Imprenta Nacional.
- JSTOR 593870.
- ^ Hispalensis, Isidorus (1773). Isidori Hispalensis Historia de regibus Gothorum, Vandalorum et Suevorum (in Latin).
- ^ Cheney, Carl D.; Jones, Michael (2000). A Handbook of Dates: For Students of British History (Rev. ed.). Cambridge University Press. p. 2.
- ISBN 978-0-415-93918-8.
- ^ "Actium, 31 BC: the beginning of the end for Mark Antony and Cleopatra". HistoryExtra. Retrieved 11 December 2023.
- ^ "Definition of EPOCH". www.merriam-webster.com. 22 November 2023. Retrieved 11 December 2023.
- ISBN 978-1-891389-85-6.
- ^ a b "The Geological Society of London - How are Geological Periods Determined?". www.geolsoc.org.uk. Retrieved 11 December 2023.
- ISBN 3-540-96683-8. p. 4.
- ^ Short, N.M. (2009). "Geologic Time" Archived 2005-04-18 at the Wayback Machine in Remote Sensing Tutorial Archived 2009-10-27 at the Wayback Machine. NASA.
- ^ Lide, D. R. (1990). Handbook of Chemistry and Physics. Boca Raton: CRC Press. pp. 14–16.
- ^ "International Stratigraphic Chart". International Commission on Stratigraphy. Archived from the original on 30 May 2014.
- ^ "Proterozoic Eon | Oxygen Crisis, Animals, & Facts | Britannica". www.britannica.com. Retrieved 11 December 2023.
- ^ "Archean Eon | Atmosphere, Timeline, and Facts | Britannica". www.britannica.com. Retrieved 11 December 2023.
- ^ "Big Bang Timeline- The Big Bang and the Big Crunch - The Physics of the Universe". www.physicsoftheuniverse.com. Retrieved 11 December 2023.
- ^ "Anno mundi | Jewish Calendar, History & Origins | Britannica". www.britannica.com. Retrieved 11 December 2023.
- ^ "Hebrew Date Converter - September 28, 2011 after sunset / 1st of Tishrei, 5772". www.hebcal.com. Retrieved 11 December 2023.
- ^ "Hebrew Date Converter - September 16, 2012 after sunset / 1st of Tishrei, 5773". www.hebcal.com. Retrieved 11 December 2023.
- ^ "Chronology - Christian History, Dates, Events | Britannica". www.britannica.com. Retrieved 11 December 2023.
- ^ "Islamic calendar | Months, Definition, & Facts | Britannica". www.britannica.com. 14 November 2023. Retrieved 11 December 2023.
- ^ "Hijri to Gregorian Date Converter - Islamic Date Converter". IslamicFinder. Retrieved 11 December 2023.
- ISBN 978-0-674-01753-5.
- ^ Gubbins, John Harrington. (1922). The Making of Modern Japan, p. 71; Mossman, Samuel. (1873). New Japan, the Land of the Rising Sun, p. 462.
- ^ a b "Calendar systems and their role in patent documentation | Epo.org". www.epo.org. Retrieved 11 December 2023.
- ^ Denis C. Feeney, Caesar's Calendar, University of California Press, Berkeley 2007, p. 139.
- ^ ISBN 978-0-521-48366-7.
- ^ "Regnal Years - The University of Nottingham". www.nottingham.ac.uk. Retrieved 11 December 2023.
- ^ "Calendar systems and their role in patent documentation | Epo.org". www.epo.org. Retrieved 11 December 2023.
- ISBN 0-571-09267-5.
- ^ "Chapter Five: Table of regnal year of English Sovereigns". Sweet & Maxwell's Guide to Law Reports and Statutes (Fourth ed.). London: Sweet & Maxwell's Guide. 1962. pp. 20–33.
- ^ "Historiography | NMU Writing Center". nmu.edu. Retrieved 11 December 2023.
- ^ "Big Bands and the Swing Era". Acoustic Music. Retrieved 11 December 2023.
- ^ "Disco | Origins, Genres & Cultural Impact | Britannica". www.britannica.com. 9 December 2023. Retrieved 11 December 2023.