Week

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(Redirected from
Seven-day week
)

A week is a unit of time equal to seven days. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days of worship. Weeks are often mapped against yearly calendars, but are typically not the basis for them, as weeks are not based on astronomy.

Ancient cultures had different "week" lengths, including ten in Egypt and an eight-day week for

Emperor Constantine officially decreed a seven-day week in the Roman Empire, including making Sunday a public holiday.[1][2]
This later spread across Europe, then the rest of the world.

World map showing the first day of the week used in different countries according to the Common Locale Data Repository[3]
  Monday
  Friday
  Saturday
  Sunday

In English, the

awareness weeks, which are designed to draw attention to a certain subject or cause. The term "week" may also be used to refer to a sub-section of the week, such as the workweek and weekend
.

Cultures vary in which days of the week are designated the first and the last, though virtually all have Saturday, Sunday or Monday as the first day. The Geneva-based ISO standards organization uses Monday as the first day of the week in its ISO week date system through the international ISO 8601 standard.[a] Most of Europe and China consider Monday the first day of the (work) week, while North America, Israel, South Asia, and many Catholic and Protestant countries, consider Sunday the first day of the week, while Saturday is judged as the first day of the week in much of the Middle East (Israel excepted) and North Africa due to the Islamic influence. Other regions are mixed, but typically observe either Sunday or Monday as the first day.[5]

The three

jum`ah, on Friday because it was described as a sacred day of congregational worship in the Quran.[6]

Name

The English word

Common Germanic *wikōn-, from a root *wik- "turn, move, change". The Germanic word probably had a wider meaning prior to the adoption of the Roman calendar, perhaps "succession series", as suggested by Gothic wikō translating taxis "order" in Luke
1:8.

The seven-day week is named in many languages by a word derived from "seven". The archaism sennight ("seven-night") preserves the old Germanic practice of reckoning time by nights, as in the more common fortnight ("fourteen-night").[7] Hebdomad and hebdomadal week both derive from the Greek hebdomás (ἑβδομάς, "a seven"). Septimana is cognate with the Romance terms derived from Latin septimana ("seven mornings").

Slavic has a formation *tъ(žь)dьnь (Serbian тједан, tjedan, Croatian tjedan, Ukrainian тиждень, tyzhden, Czech týden, Polish tydzień), from *tъ "this" + *dьnь "day". Chinese has 星期, as it were "planetary time unit". An older Chinese form is 禮拜, meaning "week, religious ceremony."

Definition and duration

A week is defined as an interval of exactly seven days,[b] so that, except when passing through daylight saving time transitions or leap seconds,

1 week = 7 days = 168 hours = 10,080 minutes = 604,800 seconds.

With respect to the Gregorian calendar:

  • 1 Gregorian calendar year = 52 weeks + 1 day (2 days in a leap year)
  • 1 week = 16006957 ≈ 22.9984% of an average Gregorian month

In a

Julian year
of 365.25 days or 52+528 ≈ 52.1786 weeks, which cannot be represented by a finite decimal expansion). There are exactly 20,871 weeks in 400 Gregorian years, so 18 April 1624 was a Thursday just as was 18 April 2024.

Relative to the path of the

lunation
or 94.637% of an average quarter lunation.

Historically, the system of dominical letters (letters A to G identifying the weekday of the first day of a given year) has been used to facilitate calculation of the day of week. The day of the week can be easily calculated given a date's

Julian day number (JD, i.e. the integer value at noon UT
): Adding one to the
modulo 7 + 1) yields that date's ISO 8601 day of the week. For example, the Julian day number of 18 April 2024 is 2460419. Calculating 2460419 mod 7 + 1 yields 4, corresponding to Thursday.[8] In 1973, John Conway devised the Doomsday rule
for mental calculation of the weekday of any date in any year.

Days of the week

An Italian cameo bracelet representing the days of the week by their eponymous deities (mid-19th century, Walters Art Museum)
Schematic comparison of the ordering of the classical planets (arranged in a circle) and the sequence of days in the week (forming a {7/3} heptagram within the circle).

The days of the week were named for the seven classical planets, which included the Sun and Moon. This naming system persisted alongside an "ecclesiastical" tradition of numbering the days in ecclesiastical Latin beginning with Dominica (the Lord's Day) as the first day. The Greco-Roman gods associated with the classical planets were rendered in their interpretatio germanica at some point during the late Roman Empire, yielding the Germanic tradition of names based on indigenous deities.

The ordering of the weekday names is not the classical order of the planets (by distance in the

Dio Cassius (early 3rd century) gives two explanations in a section of his Historia Romana after mentioning the Jewish practice of sanctifying the day called the day of Kronos (Saturday).[10]

Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Planet Sun
Moon
Mars
Mercury
Jupiter
Venus
Saturn
Greco-Roman deity Helios-Sol Selene-Luna Ares-Mars Hermes-Mercury
Jupiter
Aphrodite-Venus Cronus-Saturn
Greek:[10] ἡμέρα Ἡλίου ἡμέρα Σελήνης ἡμέρα Ἄρεως ἡμέρα Ἑρμοῦ ἡμέρα Διός ἡμέρα Ἀφροδίτης ἡμέρα Κρόνου
Latin: dies Sōlis dies Lūnae dies Martis dies Mercuriī dies Iovis dies Veneris dies Saturnī
interpretatio germanica
Sun
Moon Tiwaz
Wodanaz
Þunraz
Frige
Old English sunnandæg mōnandæg tiwesdæg wōdnesdæg þunresdæg frīgedæg sæterndæg
Indian Navagraha Suryavāra/

Bhānuvāsara/Ādityavāra

Chandravāra/

Somavāra/

Induvāsara

Mangalavāra/ Bhaumavāsara Budhavāra/

Saumyavāsara

Bṛhaspativ
āsara
Bhṛguvāsara
Shanivāra/

Sthiravāsara

An ecclesiastical, non-astrological, system of numbering the days of the week was adopted in Late Antiquity. This model also seems to have influenced (presumably via

Latin West it remains extant only in modern Icelandic, Galician, and Portuguese.[12]

"First Day" or
"Lord's Day"
(Sunday)
"Second Day"
(Monday)
"Third Day"
(Tuesday)
"Fourth Day"
(Wednesday)
"Fifth Day"
(Thursday)
"Sixth Day"
(Friday)
"Seventh Day" or
"Sabbath"
(Saturday)
Greek
Κυριακὴ ἡμέρα
/kiriaki iméra/
Δευτέρα ἡμέρα
/devtéra iméra/
Τρίτη ἡμέρα
/tríti iméra/
Τετάρτη ἡμέρα
/tetárti iméra/
Πέμπτη ἡμέρα
/pémpti iméra/
Παρασκευὴ ἡμέρα
/paraskevi iméra/[13]
Σάββατον
/sáb:aton/
Latin [dies] dominica;
rarely feria prima, feria dominica
feria secunda feria tertia feria quarta;
rarely media septimana
feria quinta feria sexta Sabbatum; dies sabbatinus, dies Sabbati;
rarely feria septima, feria Sabbati
Hebrew Hebrew: יום ראשון, romanizedYom rishon, lit.'first day' Hebrew: יום שני, romanizedYom sheni, lit.'second day' Hebrew: יום שלישי, romanizedYom shlishi, lit.'third day' Hebrew: יום רביעי, romanizedYom revi'i, lit.'fourth day' Hebrew: יום חמישי, romanizedYom chamishi, lit.'fifth day' Hebrew: יום שישי, romanizedYom shishi, lit.'sixth day' Hebrew: שבת, romanizedShabbat, lit.'Rest/cessation'

History

St. Emmeram Abbey. The week is divided into seven days, and each day into 24 hours, 96 puncta (quarter-hours), 240 minuta (tenths of an hour) and 960 momenta
(40th parts of an hour).

Ancient Near East

The earliest evidence of an astrological significance of a seven-day period is connected to

Gutian dynasty (about 2100 BCE), who built a seven-room temple, which he dedicated with a seven-day festival. In the flood story of the Assyro-Babylonian Epic of Gilgamesh, the storm lasts for seven days, the dove is sent out after seven days (similarly to Genesis), and the Noah-like character of Utnapishtim leaves the ark seven days after it reaches the firm ground.[c]

Counting from the new moon, the Babylonians celebrated the 7th, 14th, 21st and 28th of the approximately 29- or 30-day lunar month as "holy days", also called "evil days" (meaning inauspicious for certain 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".[17] On each of them, offerings were made to a different god and goddess. Though similar, the later practice of associating days of the week with deities or planets is not due to the Babylonians.[18]

Judaism

A continuous seven-day cycle that runs throughout history without reference to the phases of the moon was first practiced in Judaism, dated to the 6th century BCE at the latest.[19][20]

There are several hypotheses concerning the origin of the biblical seven-day cycle.

lunation is the implicit astronomical origin of the seven-day week,[21] and indeed the Babylonian calendar used intercalary days to synchronize the last week of a month with the new moon.[22]
According to this theory, the Jewish week was adopted from the Babylonians while removing the moon-dependency.

Enûma Eliš, which is recorded on seven tablets.[23]

In a frequently-quoted suggestion going back to the early 20th century,

Enûma Eliš, tentatively reconstructed [according to whom?] "[Sa]bbath shalt thou then encounter, mid[month]ly".[17]

However,

Babylonian exile of Judah. They also find the resemblance between the Biblical Sabbath and the Babylonian system to be weak. Therefore, they suggest that the seven-day week may reflect an independent Israelite tradition.[25][26][27][28]
Tigay writes:

It is clear that among neighboring nations that were in position to have an influence over Israel – and in fact which did influence it in various matters – there is no precise parallel to the Israelite Sabbatical week. This leads to the conclusion that the Sabbatical week, which is as unique to Israel as the Sabbath from which it flows, is an independent Israelite creation.[27][29]

The seven-day week seems to have been adopted, at different stages, by the

Tang China.[d][citation needed
] The Babylonian system was received by the Greeks in the 4th century BCE (notably via Eudoxus of Cnidus). Although some sources, such as the Encyclopædia Britannica,[31] state that the Babylonians named the days of the week after the five planets, the sun, and the moon, many scholars disagree. Eviatar Zerubavel says, "the establishment of a seven-day week based on the regular observance of the Sabbath is a distinctively Jewish contribution to civilization. The choice of the number 7 as the basis for the Jewish week might have had an Assyrian or Babylonian origin, yet it is crucial to remember that the ancient dwellers of Mesopotamia themselves did not have a seven-day week."[32] The astrological concept of planetary hours is an innovation of Hellenistic astrology, probably first conceived in the 2nd century BCE.[33]

The seven-day week was widely known throughout the

nundinal system.[36] The nundinal system had probably fallen out of use by the time Emperor Constantine adopted the seven-day week for official use in CE 321, making the Day of the Sun (dies Solis) a legal holiday.[37]

Achaemenid period

The Zoroastrian calendar follows the Babylonian in relating the 7th, 14th, 21st, and 28th of the 29- or 30-day lunar month to Ahura Mazda.[38] The forerunner of all modern Zoroastrian calendars is the system used to determine dates in the Persian Empire, adopted from the Babylonian calendar by the 4th century BCE.

Temple of Solomon
. While the seven-day week in Judaism is tied to Creation account in the Book of Genesis in the Hebrew Bible (where God creates the heavens and the earth in six days and rests on the seventh; Genesis 1:1-2:3,[39] in the Book of Exodus, the fourth of the Ten Commandments is to rest on the seventh day, Shabbat, which can be seen as implying a socially instituted seven-day week), it is not clear whether the Genesis narrative predates the Babylonian captivity of the Jews in the 6th century BCE. At least since the Second Temple period under Persian rule, Judaism relied on the seven-day cycle of recurring Sabbaths.[20]

Tablets[

lunation of 29 or 30 days basically contained three seven-day weeks, and a final week of eight or nine days inclusive, breaking the continuous seven-day cycle.[17]
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.[17]

Difficulties with

lunar cycle[40] include reconciling the differences between an unbroken week and a lunar week, and explaining the absence of texts naming the lunar week as Shabbat in any language.[41]

Hellenistic and Roman era

In Jewish sources by the time of the Septuagint, the term "Sabbath" (Greek: Σάββατον, romanizedSábbaton) by synecdoche also came to refer to an entire seven-day week,[42] the interval between two weekly Sabbaths. Jesus's parable of the Pharisee and the Publican (Luke 18:12) describes the Pharisee as fasting "twice in the week" (Greek: δὶς τοῦ σαββάτου, romanizeddis tou sabbatou). In the account of the women finding the tomb empty, they are described as coming there "toward the one of the sabbaths" (Greek: εἰς μίαν σαββάτων, τῇ μιᾷ τῶν σαββάτων);[43] translations substitute "week" for "sabbaths".

The ancient Romans traditionally used the eight-day

Roman era (2nd century).[44][20]

The continuous seven-day cycle of the days of the week can be traced back to the reign of

day of the week is 6 February 60 CE, identified as a "Sunday" (as viii idus Februarius dies solis "eighth day before the ides of February, day of the Sun") in a Pompeiian graffito. According to the (contemporary) Julian calendar, 6 February 60 was, however, a Wednesday. This is explained by the existence of two conventions of naming days of the weeks based on the planetary hours system: 6 February was a "Sunday" based on the sunset naming convention, and a "Wednesday" based on the sunrise naming convention.[45]

Islamic concept

According to Islamic beliefs, the seven-day a week concept started with the creation of the universe by Allah. Abu Huraira reported that Muhammad said: Allah, the Exalted and Glorious, created the clay on Saturday and He created the mountains on Sunday and He created the trees on Monday and He created the things entailing labour on Tuesday and created light on Wednesday and He caused the animals to spread on Thursday and created Adam after 'Asr on Friday; the last creation at the last hour of the hours of Friday, i. e. between afternoon and night.[46]

Adoption in Asia

China and Japan

The earliest known reference in Chinese writings to a seven-day week is attributed to Fan Ning, who lived in the late 4th century in the

Yi Jing and the Ceylonese or Central Asian Buddhist monk Bu Kong of the 7th century (Tang dynasty
).

The Chinese variant of the planetary system was brought to Japan by the Japanese monk

Meiji Period
(1868–1912).

India

The seven-day week was known in India by the 6th century, referenced in the

terminus ad quem (viz. 1st century) The terminus a quo cannot be stated with certainty".[47][48]

Christian Europe

The seven-day weekly cycle has remained unbroken in

computistic tables to an Ethiopic copy of an early Alexandrian table beginning with the Easter of 311 CE.[49][50]

A tradition of divinations arranged for the days of the week on which certain feast days occur develops in the Early Medieval period. There are many later variants of this, including the German Bauern-Praktik and the versions of Erra Pater published in 16th to 17th century England, mocked in Samuel Butler's Hudibras. South and East Slavic versions are known as koliadniki (from koliada, a loan of Latin calendae), with Bulgarian copies dating from the 13th century, and Serbian versions from the 14th century.[51]

Medieval Christian traditions associated with the lucky or unlucky nature of certain days of the week survived into the modern period. This concerns primarily Friday, associated with the crucifixion of Jesus. Sunday, sometimes personified as Saint Anastasia, was itself an object of worship in Russia, a practice denounced in a sermon extant in copies going back to the 14th century.[52]

eighth day", and has occasionally been so called in Christian liturgy.[e]

Justin Martyr wrote: "the first day after the Sabbath, remaining the first of all the days, is called, however, the eighth, according to the number of all the days of the cycle, and [yet] remains the first."[53]

A period of eight days, usually (but not always, mainly because of Christmas Day) starting and ending on a Sunday, is called an

Roman Catholic liturgy
. In German, the phrase heute in acht Tagen (literally "today in eight days") can also mean one week from today (i.e. on the same weekday). The same is true of the Italian phrase oggi otto (literally "today eight"), the French à huitaine, and the Spanish de hoy en ocho.

Numbering

Weeks in a Gregorian calendar year can be numbered for each year. This style of numbering is often used in European and Asian countries. It is less common in the U.S. and elsewhere.

The ISO week date system

The system for numbering weeks is the ISO week date system, which is included in ISO 8601. This system dictates that each week begins on a Monday and is associated with the year that contains that week's Thursday.

Determining Week 1

In practice week 1 (W01 in ISO notation) of any year can be determined as follows:

  • If 1 January falls on a Monday, Tuesday, Wednesday or Thursday, then the week of 1 January is Week 1. Except in the case of 1 January falling on a Monday, this Week 1 includes the last day(s) of the previous year.
  • If 1 January falls on a Friday, Saturday, or Sunday, then 1 January is considered to be part of the last week of the previous year. Week 1 will begin on the first Monday after 1 January.

Examples:

  • Week 1 of 2015 (2015W01 in ISO notation) started on Monday, 29 December 2014 and ended on Sunday, 4 January 2015, because 1 January 2015 fell on Thursday.
  • Week 1 of 2021 (2021W01 in ISO notation) started on Monday, 4 January 2021 and ended on Sunday, 10 January 2021, because 1 January 2021 fell on Friday.

Week 52 and 53

It is also possible to determine if the last week of the previous year was Week 52 or Week 53 as follows:

  • If 1 January falls on a Friday, then it is part of Week 53 of the previous year (W53-5).
  • If 1 January falls on a Saturday,
    • then it is part of Week 53 of the previous year if that is a leap year (W53-6),
    • and part of Week 52 otherwise (W52-6), i.e. if the previous year is a common year.
  • If 1 January falls on a Sunday, then it is part of Week 52 of the previous year (W52-7).

Schematic representation of ISO week date

Dominical letter(s) plus weekdays, dates and week numbers at the beginning and end of a year
Dominical
letter(s)1
Days at the start of January Effect1,2 Days at the end of December1
1
Mon
2
Tue
3
Wed
4
Thu
5
Fri
6
Sat
7
Sun
W01-13 01 Jan week ... 31 Dec week 1
Mon4
2
Tue
3
Wed
4
Thu
5
Fri
6
Sat
7
Sun
G(F) 01 02 03 04 05 06 07 01 Jan W01 ... W01 31 (30) (31)
F(E) 01 02 03 04 05 06 31 Dec W01 ... W01 30 (29) 31 (30) (31)
E(D) 01 02 03 04 05 30 Dec W01 ... W01 (W53) 29 (28) 30 (29) 31 (30) (31)
D(C) 01 02 03 04 29 Dec W01 ... W53 28 (27) 29 (28) 30 (29) 31 (30) (31)
C(B) 01 02 03 04 Jan W53 ... W52 27 (26) 28 (27) 29 (28) 30 (29) 31 (30) (31)
B(A) 01 02 03 Jan W52 (W53) ... W52 26 (25) 27 (26) 28 (27) 29 (28) 30 (29) 31 (30) (31)
A(G) 01 02 Jan W52 ... W52 (W01) 25 (31) 26 (25) 27 (26) 28 (27) 29 (28) 30 (29) 31 (30)

Notes
1. Numbers and letters in parentheses, ( ), apply to March − December in leap years.
2. Underlined numbers and letters belong to previous year or next year.
3. First date of the first week in the year.
4. First date of the last week in the year.

Other week numbering systems

In some countries, though, the numbering system is different from the ISO standard. At least six numberings are in use:[54][55] [dubious ]

System First day of week First week of year contains Can be last week of previous year Used by or in
ISO 8601 Monday 4 January 1st Thursday 4–7 days of year yes EU (exc. Portugal) and most of other European countries, most of Asia and Oceania
Middle Eastern Saturday 1 January 1st Friday 1–7 days of year yes Much of the Middle East
Western traditional Sunday 1 January 1st Saturday 1–7 days of year yes Canada, United States, Iceland, Portugal, Japan, Taiwan, Thailand, Hong Kong, Macau, Israel, Egypt, South Africa, the Philippines, and most of Latin America
Broadcast Calendar
Monday 1 January 1st Sunday 1–7 days of year yes Broadcast services in the United States[56]

Because the week starts on either Saturday, Sunday, or Monday in all these systems, the days in a

workweek
, Monday through Friday, will always have the same week number within a calendar week system. Quite often, these systems will agree on the week number for each day in a workweek:

Note that this agreement occurs only for the week number of each day in a work week, not for the day number within the week, nor the week number of the weekends.

The epi week (epidemiological week) is used to report healthcare statistics, as with COVID-19 cases:[57]

The epidemiological week begins on Sunday and ends on Saturday. The first epidemiological week of the year ends on the first Saturday of January, provided that it falls at least four or more days into the month. Therefore, the first epidemiological week may actually begin in December of the previous year.

Uses

The semiconductor package date code is often a 4 digit date code YYWW where the first two digits YY are the last 2 digits of the calendar year and the last two digits WW are the two-digit week number.[58][59]

The tire date code mandated by the US DOT is a 4 digit date code WWYY with two digits of the week number WW followed by the last two digits of the calendar year YY.[60]

"Weeks" in other calendars

The term "week" is sometimes expanded to refer to other time units comprising a few days. Such "weeks" of between four and ten days have been used historically in various places.[61] Intervals longer than 10 days are not usually termed "weeks" as they are closer in length to the fortnight or the month than to the seven-day week.

Pre-modern

Calendars unrelated to the Chaldean, Hellenistic, Christian, or Jewish traditions often have time cycles between the day and the month of varying lengths, sometimes also called "weeks".

An

French Republican Calendar
, dividing its 30-day months into thirds).

A six-day week is found in the

Guipuscoan Basque.[62]

The Aztecs and Mayas used the

Yucatec Maya) into 20 weeks of 13 days (known in Spanish as trecenas). They also divided the solar year into 18 periods (winal) of 20 days and five nameless days (wayebʼ), creating a 20-day month divided into four five-day weeks. The end of each five-day week was a market day.[63][64]

The Balinese

Pawukon
is a 210-day calendar consisting of 10 different simultaneously running weeks of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 days, of which the weeks of 4, 8, and 9 days are interrupted to fit into the 210-day cycle.

Modern reforms

The

Eastman Kodak Company
for decades.

A 10-day week, called a décade, was used in France for nine and a half years from October 1793 to April 1802; furthermore, the Paris Commune adopted the Revolutionary Calendar for 18 days in 1871.

The Bahá'í calendar features a 19-day period which some classify as a month and others classify as a week.[65]

Soviet

Soviet calendar, 1930.
Five colors of five-day work week repeat.
Soviet calendar, 1933.
Rest day of six-day work week in blue.
Days of each Gregorian month in both calendars are grouped vertically into seven-day weeks.

In the Soviet Union between 1929 and 1940, most factory and enterprise workers, but not collective farm workers, used five and six day work weeks while the country as a whole continued to use the traditional seven day week.[66][67][68]

From 1929 to 1951, five national holidays were days of rest (22 January, 1–2 May, 7–8 November). From autumn 1929 to summer 1931, the remaining 360 days of the year were subdivided into 72 five day work weeks beginning on 1 January. Workers were assigned any one of the five days as their day off, even if their spouse or friends might be assigned a different day off. Peak use of the five day work week occurred on 1 October 1930 at 72% of industrial workers. From summer 1931 until 26 June 1940, each Gregorian month was subdivided into five six day work weeks, more-or-less, beginning with the first day of each month. The sixth day of each six day work week was a uniform day of rest. On 1 July 1935 74.2% of industrial workers were on non-continuous schedules, mostly six day work weeks, while 25.8% were still on continuous schedules, mostly five day work weeks. The Gregorian calendar with its irregular month lengths and the traditional seven day week were used in the Soviet Union during its entire existence, including 1929–1940; for example, in the masthead of Pravda, the official Communist newspaper, and in both Soviet calendars displayed here. The traditional names of the seven day week continued to be used, including "Resurrection" (Воскресенье) for Sunday and "Sabbath" (Суббота) for Saturday, despite the government's official atheism.

See also

Notes

  1. ^ "ISO 8601 Data elements and interchange formats – Information interchange – Representation of dates and times" is an international standard covering the exchange of date- and time-related data.
  2. ^ In pre-modern times, days were measured either from sunset to sunset, or from sunrise to sunrise so that the length of the week (and the day) would be subject to slight variations depending upon the time of year and the observer's geographical latitude.
  3. short chronology places Gudea in the 22nd century BCE. By contrast, Anthony R. Michaelis claims that "the first great empire builder, King Sargon I of Akkad ([ruled] 2335 to 2279 BCE [viz., middle chronology]), decreed a seven-day week in his empire. He lived for 56 years, established the first Semitic Dynasty, and defeated the Sumerian City-States. Thus the Akkadian language spread, it was adopted by the Babylonians, and the seven-day week was similarly inherited from him."[15] The number seven is significant in Sumerian mythology.[16]
  4. ^ It was transmitted to China in the 8th century by Manichaeans, via the country of Kang (a Central Asian polity near Samarkand). Tang-era adoption is documented in the writings of the Chinese Buddhist monk
    Yi Jing and the Ceylonese Buddhist monk Bu Kong
    . According to the Chinese encyclopedia
    Jin dynasty
    ), based on a reference by a Jin era astrologer, Fan Ning (范寧 / 范宁). The Cihai under the entry for "seven luminaries calendar" (七曜曆 / 七曜历, qī yào lì) has: "method of recording days according to the seven luminaries [七曜 qī yào]. China normally observes the following order: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. Seven days make one week, which is repeated in a cycle. Originated in ancient Babylon (or ancient Egypt according to one theory). Used by the Romans at the time of the 1st century CE, later transmitted to other countries. This method existed in China in the 4th century. It was also transmitted to China by Manichaeans in the 8th century from the country of Kang () in Central Asia."
    [30]
  5. nundinal cycle (literally "nine-days" cycle, describing an eight-day week) of the Roman calendar, or the Resurrection of Jesus
    (after a period of less than 48 hours) being described (in texts derived from Latin) as happening on the "third day".

References

  1. ^ Ring, Rosanna (22 January 2021). "A history of time – the story behind our days, weeks, and months St Neots Museum". St Neots Museum. Retrieved 6 January 2023.
  2. ^ Why Are There Seven Days in a Week?. Discover (15 January 2020). Retrieved 2022-10-22.
  3. ^ "Territory Information". www.unicode.org. Retrieved 23 August 2023.
  4. ^ Lagasse, Paul (2018). "Week". The Columbia Encyclopedia. Columbia University Press.
  5. ^ "Territory Information". www.unicode.org. Retrieved 6 November 2020.
  6. ^ Aslan, Rose (19 March 2019). "What is the significance of Friday prayers in Islam?". The Conversation. Retrieved 10 March 2023.
  7. ^ sennight at worldwidewords.org (retrieved 12 January 2017)
  8. ^ Richards, E. G. (2013). "Calendars". In S. E. Urban & P. K. Seidelmann, eds. Explanatory Supplement to the Astronomical Almanac, 3rd ed. (pp. 585–624). Mill Valley, Calif.: University Science Books. 2013, pp. 592, 618. This is equivalent to saying that JD0, i.e. 1 January 4713 BCE of the proleptic Julian calendar, was a Monday.
  9. ^ E. G. Richards, Mapping Time, the Calendar and History, Oxford 1999. p. 269.
  10. ^ a b Dio Cassius. Ῥωμαϊκὴ Ἱστορία. Book 37, Sections 16-19. English translation.
  11. ^ Max Vasmer, Russisches etymologisches Wörterbuch, s.v. понедельник; however, the Slavic languages later introduced a secondary numbering system that names Tuesday as the "second day".
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  62. ^ Astronomy and Basque Language, Henrike Knörr, Oxford VI and SEAC 99 "Astronomy and Cultural Diversity", La Laguna, June 1999. It references Alessandro Bausani, 1982, The prehistoric Basque week of three days: archaeoastronomical notes, The Bulletin of the Center for Archaeoastronomy (Maryland), v. 2, 16–22. 1. astelehena ("week-first", Monday), 2. asteartea ("week-between", Tuesday), 3. asteazkena ("week-last", Wednesday).
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Further reading