Why We Have 7 Days in a Week

(Photo : Pixabay.com)

People at work and school always look forward to the weekend. But having seven days in a week has been the case for a very long time that no one even asks the reason behind it. Our busy lifestyles prevent contemporary society from thinking, and reflecting life's simplest, particular observations.

The summation of our time is due to the movements of the planets, moon, and stars. A day is completed with one full rotation of the Earth around its axis. The revolution of the Earth across the solar system takes 364 and ¼ days that makes one year.

Most of these divisions of the passage of time make sense based on the movements of the Earth and Sun (days and years), as well as the fluctuations of the moon (months), but what is the real reason behind having 7 days in a week?

A straightforward answer is the Babylonians broke down the lunar month into more manageable chunks of seven days, while the Greeks and Romans made various other changes to arrive at what we have today.

Some experts believe the ancient Babylonians settled on a seven-day week because the ancient Babylonians believed the number seven had a mystical significance to it.

In the first civilizations of the Middle East, Mesopotamian astrologers designated one day for each of the seven most prominent objects in the sky visible to the naked eye. They adopted the number seven because they observed seven celestial bodies - the Sun, the Moon, Mercury, Venus, Mars, Jupiter, and Saturn.

Today's Gregorian calendar is ultimately based on the phases of the Moon and it takes the Moon around 29.5 days to cycle through all Moon phases. It made sense to break it down into smaller segments, so the Babylonians rounded the Moon cycle down to 28 days and divided this time into 4 periods each with 7 days, using leap days to stay in sync with the Moon phases in the long-run.

Moreover, the rituals implemented every seven days may have given rise to the seven-day week.

In a seven-day week, the Babylonians held the seventh day of each week as holy, much like the Jews did and still do today. They held the final seventh day of the month as a day of rest and worship.

The phases of the Moon do not exactly coincide with the solar calendar, with each cycle 27 days and seven hours long, and there are 13 phases of the Moon in each solar year.

Meanwhile, other civilizations selected different numbers -- just like the Egyptians, whose week was 10 days lengthy; or the Romans, whose week lasted eight.

Because of the lunar cycle, the Babylonians would have three seven-day weeks in a row, followed by one week of 8-9 days, to account for the lag.

The Jews also adopted a seven-day cycle, because the Lord took 7 days to create the universe as reported in Genesis.

Then came the Greeks who also used a seven-day week based on celestial bodies, which were then named after their gods (Sun, Moon, Ares, Hermes, Zeus, Aphrodite, and Cronus).