Seven-day week: Wikis


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The seven-day week is used by the majority of the world and is the international standard as specified in ISO 8601.





All early cultures were exposed to the night sky. The seven celestial objects that are visible to the naked eye and moved in a way that clearly indicated they were not stars were hence known as "planets," or "wandering stars," in the ancient world, and they worked their way into the myths and legends of most early cultures. Time was and still is easily measured by celestial events; the spring equinox for example, occurs approximately every 365 days. It was easy to adapt the other 7 objects clearly seen floating about in the sky to measure the passage of time. The Sun, Moon and five visible planets gave their names to the weekly cycle of days.

Celestial Object Sumerian Babylonian Greek Latin Sanskrit Week Day
Sun Utu Shamash Helios Sol Ravi Sunday
Moon Nanna Sin Selenê Luna Som Monday
Mars Gugalanna Nergal Ares Mars Mangala Tuesday
Mercury Enki Nabû Hermes Mercurius Budha Wednesday
Jupiter Enlil Marduk Zeus Iuppiter Brihaspati Thursday
Venus Inanna Ishtar Aphrodite Venus Shukra Friday
Saturn Ninurta Ninurta Kronos Saturnus Shani Saturday

This pattern lent itself to early religious teachings (Greek mythology for example) for most all knowledge—astronomy, reading and writing, and most forms of education—came from religious centers. Two in particular—astronomy and religion—often went hand in hand.

The Lebombo bone suggests people have been counting days using the lunation since at least 35000 BC. Though the lunar month lasts 29.53059 days, the lunar cycle can be approximated as lasting 29 or 30 days. Periods of seven days divide the month into four, roughly corresponding to the quarters of the moon. In addition to conveniently marking the new and full moon, groups of seven may have been preferred because seven figures prominently in astronomy. There are the seven famous stars of the Pleiades constellation, and the seven wanderers—the Sun, the Moon, Mars, Mercury, Jupiter, Venus and Saturn—that move relative to the background stars. More esoterically, seven also appears in the relationship between solar and lunar cycles. The Sumerians had calculated that there were 235 lunar cycles equaling nearly 19 solar cycles, we call the Metonic cycle, requiring seven leap months to keep the lunar year in line with the solar year.


The Babylonian Imago Mundi, dated to the 6th century BC (Neo-Babylonian Empire).[1] The map shows Babylon on the Euphrates, surrounded by a circular landmass showing Assyria, Armenia and several cities, in turn surrounded by a "bitter river" (Oceanus), with seven islands arranged around it so as to form a seven-pointed star.

Counting from the new moon, the Babylonians celebrated the 7th, 14th, 21st, and 28th as "holy-days", also called "evil days" (meaning "unsuitable" for prohibited activities). On these days officials were prohibited from various activities and common men were forbidden to "make a wish", and at least the 28th was known as a "rest-day". On each of them, offerings were made to a different god and goddess. Tablets from the sixth-century B.C. reigns of Cyrus the Great and Cambyses indicate these dates were sometimes approximate. The lunation of 29 or 30 days basically contained three seven-day weeks, and a final week of nine or ten days inclusive, breaking the continuous seven-day cycle. The Babylonians additionally celebrated the 19th as a special "evil day", the "day of anger", because it was roughly the 49th day of the (preceding) month, completing a "week of weeks", also with sacrifices and prohibitions. Further, reconstruction of a broken tablet seems to define the rarely attested Sapattum or Sabattum as the 15th day of the lunation: this word is cognate with Hebrew Shabbat, but is monthly rather than weekly; it is regarded as a form of Sumerian sa-bat ("mid-rest"), attested in Akkadian as um nuh libbi ("day of mid-repose").[2]


The earliest evidence of continuous use of a seven-day week appears with the Jews during the Babylonian Captivity in 586 BCE[3], after the destruction of the first Temple.

A seven-day week is mentioned in the Creation story contained in the Book of Genesis, in the Hebrew Bible, where God is said to have created the heavens and the earth in six days and rested on the seventh (Genesis 1:1-2:3). Also, in the Book of Exodus, the fourth of the ten commandments is to rest on the seventh day, the Sabbath, which can be seen as implicating a seven-day week social institution (Exodus 20:8-11).

Pre-Christian Europe

The ancient Romans traditionally used the eight-day nundinal cycle, but after the adoption of the Julian calendar, in the time of Augustus, the seven-day week came into use. For a while, the week and the nundinal cycle coexisted, but by the time the week was officially adopted by Constantine in AD 321[4] the nundinal cycle had fallen out of use.

One Roman date with an associated day of the week exists from the 1st century and it agrees with the modern sequence, if properly interpreted.

Christian Europe

The seven-day weekly cycle is known to have remained unbroken in Europe for almost two millennia, despite changes to the Alexandrian, Julian, and Gregorian calendars.

The date of Easter Sunday can be traced back through numerous computistic tables to an Ethiopic copy of an early Alexandrian table beginning with the Easter of 311 CE[5]

Replacement for earlier 7-day week by later 7-day week


Prior to the Akkadian adoption of a 7-day week based on the names of major deities (identified with planets) of the pantheon, there had been in use a system of 7 days based on the 7 "Protective Spirits" (each clad in a uniform of a particular color, and each assigned to a particular city), thus[6] :-

  • "first" "day of life, offspring of UNUG (Uruk)" -- "clad in red"
  • "second" "day of plenty, son of Nippur" -- "clad in white"
  • "third" "day of splendor, who grew up in Eri-dùg" -- "clad in white ... with black"
  • "fourth" "good day, who appeared in Kul-lab" -- "clad in black"
  • "fifth" "fair-faced day, brought up in Ki-si (Keš)" -- "clad in yellow"
  • "sixth" "righteous day, exalted judge of La-gaš" -- "clad in blue"
  • "seventh" "day that gives life to the slain, shade of Šu-rup-pa-ak" -- "clad in orange"


Prior to the Hellenistic adoption of a 7-day week based mainly on the names of the Olympian deities, there had been in use a cycle of "the seven days of the sacred planetary week"[7] based entirely on the names of the Titans (as married couples), thus[8] :-

  1. (Sunday :) Theiā & Hyperiōn
  2. (Monday :) Phoibē & Atlas
  3. (Tuesday :) Dionē & Krios
  4. (Wednesday :) Mētis & Koios
  5. (Thursday :) Themis & Eurymedōn
  6. (Friday :) Tēthys & Ōkeanos
  7. (Saturday :) Rheiā & Kronos


Prior to their adoption from the Spanish conquistadores of the modern European 7-day week, the Maya made use of "Glyph Y of the Supplementary Series where it is governed by a seven-day cycle that may be a "planetary week" (Yasugi and Saito 1991)"[9].

"Thomas Barthel was the first to recognize that seven of the symbols in the so-called "planetary band" ... were the symbols of the planets in their weekday order."[10] These are :-

  1. "stylized head of the Sun god"
  2. "crescent moon"
  3. "patron god of the month Zip, the Mars deity"
  4. "The crossbands ... refer to a Mercury marker of ... the cross ... as a symbol of Quetzalcoatl, whom Kelley has identified as Mercury."
  5. (planet Jupiter)
  6. "The "star" glyph used for Venus"
  7. "the "night" glyph ... as "pseudo-Sun" may refer to the Saturnian"

Adoption after other systems


The earliest known reference in Chinese writings to a seven-day week is attributed to Fan Ning, who lived in the late 4th century of the Jin Dynasty, while diffusions from the Manichaeans are documented with the writings of the Chinese Buddhist monk Yi Jing and the Ceylonese or Central Asian Buddhist monk Bu Kong of the 7th century (Tang Dynasty).


France discontinued the seven-day week for a ten-day week with the introduction of the republican calendar in 1793. The Concordat of 1801, which re-established the Roman Catholic Church in France, also restored the seven-day week, beginning with Easter Sunday, 18 April 1802.


The Chinese transliteration of the planetary system was soon brought to Japan by the Japanese monk Kobo Daishi. Surviving diaries of the Japanese statesman Fujiwara Michinaga show the seven-day system in use in Heian Period Japan as early as 1007. In Japan, the seven-day system was kept in use for astrological purposes until its promotion to a full-fledged Western-style calendrical basis during the Meiji era.


The seven-day week may have been in use during the Vedic Period, although according to Pandurang Vaman Kane author of History of Dharmasastra "this is not conclusive".

The Pañcasiddhāntikā mentions 'Monday'. The Garga dated 1st Century BCE, refers to the seven-day week, Sunday to Saturday.

He concludes "the above references furnish a terminus ad quem (viz. 1st century BCE–1st century CE) The terminus a quo cannot be stated with certainty".[11][12]

Soviet Union

In 1929 USSR discontinued the seven-day week for a five-day week, then a six-day week. They reintroduced the seven-day week on 27 June 1940.

Week numbering

Weeks in a Gregorian calendar year can be numbered for each year. This style of numbering is commonly used (for example, by schools and businesses) in some European and Asian countries, but rare elsewhere.

ISO 8601 includes the ISO week date system, a numbering system for weeks – each week begins on a Monday and is associated with the year that contains that week's Thursday (so that if a year starts in a long weekend Friday–Sunday, week number one of the year will start after that). For example, week 1 of 2004 (2004W01) ran from Monday 29 December 2003 to Sunday, 4 January 2004, because its Thursday was 1 January 2004, whereas week 1 of 2005 (2005W01) ran from Monday 3 January 2005 to Sunday 9 January 2005, because its Thursday was 6 January 2005 and so the first Thursday of 2005. The highest week number in a year is either 52 or 53 (it was 53 for year 2004).

The numbering system in different countries may deviate from the international ISO standard. There are at least six possibilities:[13][14]

First day of week First week of year contains Weeks assigned twice Used by/in
Monday 1 January 1st Sunday 1–7 days of year yes UK (also uses Sunday)
Monday 4 January 1st Thursday 4–7 days of year no Most of Europe ISO 8601(1988) except UK, European Norm EN 28601 (1992)
Monday 7 January 1st Monday 7 days of year no
Wednesday 1 January 1st Tuesday 1–7 days of year yes
Saturday 1 January 1st Friday 1–7 days of year yes Most of the Gulf Cooperation Council countries
Sunday 1 January 1st Saturday 1–7 days of year yes UK, Australia, Canada, New Zealand, USA

Facts and figures

  • 1 week = 7 days = 168 hours = 10,080 minutes = 604,800 seconds (except at daylight saving time transitions or leap seconds)
  • 1 Gregorian calendar year = 52 weeks + 1 day (2 days in a leap year)
  • 1 week = 23.01% of an average month

In a Gregorian mean year there are approximately 365.2425 days, and thus approximately 52.1775 weeks (unlike the Julian year of 365.25 days or 52+528 weeks, which cannot be represented by a finite decimal expansion). There are exactly 20871 weeks in 400 Gregorian years, so 10 April 1605 was a Sunday just like 10 April 2005.

A system of Dominical letters has been used to determine the day of week in the Gregorian or the Julian calendar.

See also


  1. ^ Siebold, Jim. "Slide 103". Retrieved 2009-01-21.  
  2. ^ Pinches, T.G. (2003). "Sabbath (Babylonian)". in Hastings, James. Encyclopedia of Religion and Ethics. 20. Selbie, John A., contrib. Kessinger Publishing. pp. 889–891. ISBN 9780766136984. Retrieved 2009-03-17.  
  3. ^ Senn, Frank C. (1997). Christian Liturgy: Catholic and Evangelical. Fortress Press. ISBN 0800627261, 9780800627263.  
  4. ^ Zerubavel, Eviatar (1989). The Seven Day Circle: The History and Meaning of the Week. University of Chicago Press. pp. 45. ISBN 0226981657, 9780226981659.  
  5. ^ Neugebauer, Otto (1979). Ethiopic astronomy and computus. Verl. d. Österr. Akad. d. Wiss. ISBN 3700102895, 9783700102892.  
  6. ^ Wiggermann 1992, pp. 8 & 9
  7. ^ Graves 1955, §1.3
  8. ^ Graves 1955, §1.d
  9. ^ Milbrath 2002, p. 128
  10. ^ Kelley 2005, p. 362a
  11. ^ Shashi, Shyam Singh (2000). Encyclopaedia Indica India, Pakistan, Bangladesh Vol. 76 Major dynasties of ancient Orissa: India, Pakistan, Bangladesh. Anmol Publications PVT. LTD. pp. 114–115. ISBN 8170418593, 9788170418597.  
  12. ^ Kane, Dr. Pandurang Vaman (1930-1962). History of Dharmasastra.  
  13. ^ Weeknumber sorted by definition
  14. ^ Calendar Weeks


  • Robert Graves : The Greek Myths. 1955.
  • David H. Kelley : "Mesoamerica". In :- Exploring Ancient Skies : an Encyclopedic Survey of Archaeoastronomy. Springer Verlag, 2005.
  • Susan Milbrath : "The Planet of Kings : Jupiter in Maya Cosmology". In :- Heart of Creation : the Mesoamerican World and Legacy of Linda Schele. University of Alabama Press, 2002. pp. 118-142
  • CUNEIFORM MONOGRAPHS, 1 = F. A. M. Wiggermann : Mesopotamian Protective Spirits. Styx & PP Publications, Groningen, 1992.
  • RESEARCH REPORTS ON ANCIENT MAYA WRITING, 34 = Yoshiho Yasugi & Kenji Saito : Glyph Y of the Maya Supplementary Series. Center for Maya Research, Washington (DC), 1991.

External links

  • Week Wheel for Children


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