This is how time was constructed –>

• The DAY – Sun – its obvious how we created the 24 hour day because the Sun comes up ever 24 hours.
• The MONTH – Moon – Ancient people noticed the Moon was in a cycle —waxing, full, waning, disappearing—approximately every 29.5 days. A lunar cycle was one of humanity’s first clocks.
• The YEAR – Sun – Ancient people tracked the Sun’s path and realized the seasons are on a cycle –approximately 365 days. This allowed agriculture to survive on following the Sun’s yearly path, so it became sacred.
• The WEEK is different, though. Humans took the seven planets visible to the naked eye—the Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn—and assigned each one a day. That’s astrology in its original form: a symbolic ordering of time based on celestial planets.

Its the Babylonians who assigned each day to one of the seven visible planets in the sky. The seven-day week likely originates with the Babylonians/Chaldeans (around 6th–5th century BCE). Astronomers and Astrologers associated the seven visible celestial bodies with specific days.

The number 7 also had religious and mystical significance in many ancient cultures, including Judaism (the creation story in Genesis, seven days of creation).

Every time you say a day of the week, you’re actually naming a celestial body.

The Romans originally used an 8-day week (the nundinal cycle) for market days. But, around the 1st century BCE, influenced by Hellenistic astrology (and possibly Babylonian practices via the Greeks), the Romans shifted to a 7-day week and named each day after the seven classical planets, which is the structure we mostly follow today:

Sunday is the Sun’s day.
Monday is the Moon’s day.
Tuesday comes from Mars.
Wednesday from Mercury.
Thursday from Jupiter.
Friday from Venus.
Saturday from Saturn.

So the Babylonians set the astrological/planetary pattern, and the Romans formalized the week in a way that spread throughout Europe.

It took a while for everyone to be on the same page. There was an 8-day week and 7-day week for a while, going at the same time. But, eventually, due to Judaism, Christianity, Astrology, and general cultural mixing — Rome officially adopted the 7-day week.

XOXO Allison