They also find the resemblance between the biblical Sabbath and the Babylonian system weak.Therefore they suggested that the seven-day week may reflect an independent Israelite tradition.The Babylonian system was received by the Greeks in the 4th century BC (notably via Eudoxus of Cnidus).However the designation of the seven days of the week to the seven planets is an innovation introduced in the time of Augustus.This characteristic was apparently discussed in Plutarch in a treatise written in c.AD 100, which is reported to have addressed the question of Why are the days named after the planets reckoned in a different order from the actual order? An ecclesiastical, non-astrological, system of numbering the days of the week was adopted in Late Antiquity.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 remainder after dividing the Julian day number by seven (JD modulo 7 1) yields that date's ISO 8601 day of the week (for example, the Julian day number of 7 November 2017 is 2458065.
Friedrich Delitzsch and others suggested that the seven-day week being approximately a quarter of a lunation is the implicit astronomical origin of the seven-day week According to this theory, the Jewish week was adopted from the Babylonians while removing the moon-dependency. Tigay and others claimed that the sabbath is mentioned as a day of rest in some of the earliest layers of the Pentateuch dated to the 9th century BC at the latest, centuries before Judea's Babylonian exile.
The week is divided into seven days, and each day into 96 puncta (quarter-hours), 240 minuta (tenths of an hour) and 960 momenta (40th parts of an hour). It is the standard time period used for cycles of rest days in most parts of the world, mostly alongside—although not strictly part of—the Gregorian calendar.
ISO 8601 includes the ISO week date system, a numbering system for weeks within a given year – 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).
Calculating (2458065 mod 7 1) yields 2, corresponding to Tuesday.).
The days of the week were originally named for the classical planets.