Who invented our time system?
Where and when did weeks and months as we know them originate?
Our time system has been adjusted over thousands of years. Some 4,000 years ago, the Babylonians in what is now Iraq introduced a calendar that divided time into years, months, and weeks. The Babylonians based their calendar on the motions of major heavenly bodies. A year was the time it took Earth to orbit the Sun once, and a month was the time it took the Moon to complete one orbit around Earth. The Babylonians knew the Sun and six "planets" – the Moon, Mars, Jupiter, Mercury, Venus, and Saturn. Although the week has nothing to do with astronomical phenomena, the seven "heavenly bodies" probably formed the basis of the seven day week.
In Ancient Egypt, daytime was divided into 12 hours by using sundials. Twelve is a very flexible number for time, because unlike the number ten, it can be divided into thirds, quarters, sixths and twelfths.