Peter Coveney and Roger Highfield contest the characterisation of the week as being linked to celestial movements. Instead they note that the week is contingent upon social norms and contexts, which are distinct from the rhythms and revolutions of the planets.
The week does not have a basis in the motions of the heavens. As Michael Yong, Director of the Institute of Community Studies in London, put it: ‘The Sun has not been the only master. Humans can create their own cycles without having to rely on the ready-made ones. No other creature has demonstrated so much independence from astronomy. No other creatures has the week.’ The week probably arose from the practical need for societies to have a time unit smaller than a month but longer than a day. Communities run more smoothly when there are regular opportunities for laundry, worship and holidays. Ancient Colombia used to have a three-day week. The ancient Greeks favoured ten-day weeks while some primitive tribes today prefer a week of only four days. The seven-day week derived from the Babylonians who in turn influenced the Jews (though the former ended it with an ‘evil day’ rather than a Sabbath, when taboos were enforced to appease the gods – perhaps the origin of the restrictions on Sunday activities). Its popularity has defeated a number of attempts at change. The French tried to decimalise it after the Revolution but their ten-day week was scrapped by Napoleon. In 1929 the Soviets attempted to introduce a few-day week and in 1932 extended it to six, but by 1940 the seven-day week had returned. Just as the week ignores astronomy, so does the modern technology of timekeeping (Coveney and Highfield 1990, 43).
Coveney, Peter, and Highfield, Roger. 1990. The arrow of time: A voyage through science to solve time’s greatest mystery. London: Flamingo.