Seven day weeks have been around for over thousands of years ago
The movement of the moon is a month, the sun is a year, and the earth on the axis makes a day but we don't have an exact explanation on the week
Many calendars say that Sunday is the first day of the week and Saturday is the last, however, people believe that Monday is the first day and Sunday is the last
There might be a week because the ancient Babylonian thought the number seven was a significant number
A theory is that it Babylonians marked after the moon's cycles. Like on the 1st day is a crescent, on about the seventh day there is a waxing moon and on about the 14th day you can see a full moon, the 21st, a waning half moon, 28th is a waning crescent
Since the moon phases weren’t exactly 7 days, the Babylonians had three 7 day weeks and then an 8 or 9 day week to match up with the moon phases
To the Babylonians, the last day of the week was considered unlucky so there were restrictions on what you could and couldn’t do to stay safe
Ancient Jewish Theories
It can be traced to the bible too. The bible says that god made the world in six days and rested on the seventh. Cultures believed they should work for six days and rest on the seventh too.
The Jews saw the last day of the week as holy and to rest
Ancient Roman Theories
Ancient Romans used 8 day weeks
On the last day of the week for Romans, they went shopping for goods such as food and clothing
The Romans used letters instead of numbers to mark the days of the week
Soon the Julian calendar came and there was no 8th day of the week, the calendar soon became popular and 8 days in the week was gone after a century
In 1793 France favored 10 days of the week and switched to that, however, 9 years later it was changed back to 7 days of the week
Sunday is a work day in Muslim countries and in Israel
Here in the Us, Labor day. Memorial day, Columbus day, and Veterans day are always on Monday
In Australia, Thursday is the day stores stay open later. Thursday is also the day were Australians make the most money
"Why We Have a Seven Day Week and the Origin of the Names of the Days of the Week." Today I Found Out. N.p., 09 Apr. 2013. Web. 11 May 2016.
"Why Are There Seven Days in a Week?" Wonderopolis. N.p., n.d. Web. 11 May 2016.
Lutwyche, Jayne. "Why Are There Seven Days in a Week?" BBC News. BBC, 22 Jan. 2013. Web. 12 May 2016.