How Our Ancestors Made The Week
The Astronomical Marker
We often do not give much attention or questioning to every day customary conventions. Perhaps one of those conventions that is looked over the most are the days themselves. It is quite odd, when one thinks of the matter, that we have a convention such as the week. It is easily recognizable why we have a measure for a year or a month, these are astronomical markers. But, does a week represent an astronomical marker, or anything that could give us the measure of a week?
In my research for the reasoning of a week, I have come across many incorrect reports that the week does not represent any astronomical significance. They often cite that the year represents a full revolution of Earth around the Sun, and the month a revolution of the Moon around the Earth. But, then say that the week does not represent some predictable astronomical feature. That is false, and will be expounded on soon.
There is not a perfect indicator of any astronomical event that constitutes a week, but neither is there a perfect indicator for a month or a year. The full cycle of the Moon takes 29 and a half days, and its revolution around the Earth takes 27 and almost a half day. It takes the Earth 365.25 days to make a complete revolution around the Sun. In fact, a day is not even 24 hours, to be precise, it takes the Earth 23 Hours and 56 minutes to rotate on its axis.
The Weekly Indicator: The Moon!
As we have settled that no measure of the calendar so far is perfect, meaning that neither the day, month, or year has a nicely rounded measurement of time associated with it. And once we have eliminated this misconception, that the calendar is represented by some whole or finished cycle, we can more easily see where it is that we created the convention of the week.
It would be helpful if, when constructing the argument for understanding the week, we tried to imagine what it would be like for our ancestors who looked up to the moon with far less advanced instruments of science and far more ignorance than we have. Specifically, if we decided to disregard a few conventions that we have today (the Gibbous waxing and waning Moons) and only focused on a more simple separation of the Moon’s cycle, then the week is revealed to us.
Consider a cycle of the Moon in which we only distinguish between full, half and new Moons. Remember, we must think of these periods of differentiation in a cycle, with special notice to there being two different half Moons being revealed, and the cycle ending where it began (where the natural end to a cycle is considered to be).
Let’s use a real example to demonstrate how the cycle works. On July 23rd 2017 in Los Angeles, CA there was a New Moon (the beginning of our cycle). Then on July 30th, 7 days later, there was a half Moon (commonly called the first quarter). Then on August 7th, 8 days later, there was a full Moon. Then on August 14th, 7 days later, there was another half Moon (this ‘third quarter’ revealed the other half of the Moon not revealed in the ‘first quarter’). Finally, on August 21st, again 7 days later, our cycle ends with another New Moon.

If one observes this chart correctly, along with the data from the example given above, it is apparent that the phases described above follow (sometimes just nearly) a cycle of 7 days. Following this chart, the cycle begins with a New Moon, then 7 days later we have a half Moon, another (approximately) 7 days later we have a full Moon, another 7 days later we have another half Moon, then finally after another (approximately) 7 days we begin our cycle again with a New Moon.
What Our Ancestors Saw
It is easily realized that one must be skeptical when hearing another speculate as to what our ancestors were thinking of when they observed the sky and all its wonders. But, this becomes a much easier and more believable task when our ancestors wrote about it and preserved it in the language we speak today. Then, one need not speculate, but simply observe the evidence and interpret it however one can.
When our ancestors looked up, they noticed a general pattern of 7 day intervals between significant phases of the Moon’s cycle. As has been stated above, the Moon’s cycle does not neatly fall into 7 day intervals. But this small remainder of time did not inhibit our ancestors from creating a 7 day week. Just like the remainders of time, as was stated above, between the year or month did not inhibit our ancestors and does not inhibit us from breaking down the time as we do.
Our ancestors also had another reason for 7 being a significant number and purpose for there being a 7 day week. But once again, we must not only unlearn, but not even know what there was to learn. For to understand what our ancestors looked upon when they looked at the sky, they had yet questions to be formulated. So, imagining them asking questions like, “Does the Sun revolve around the Earth, or the Earth the Sun?”, or “Are the Moon and Sun different from the rest of the physical bodies in the sky?” are already questions that require an incredibly dense and worthy amount of knowledge of the cosmos.
When our ancestors looked up to the skies they did not make the distinction between Sun and Moon, as we can make the distinction between their physical properties etc. They simply saw two large bodies in the sky that had an apparent effect on the Earth they lived. The Moon on the tides, the Sun with the crops, and much more. They also noticed as the year progressed that 5 other bodies in the cosmos seemed to have an effect on the Earth they lived on (or they thought). Mercury, Venus, Mars, Saturn, and Jupiter all show up at different times of the year, during different seasons, and therefore made our ancestors believe that these ‘heavenly’ bodies had an effect on the Earth. These five planets (now we know they are planets) plus the Sun and Moon are all the visible bodies in the ‘heavens’ that behave differently than the other multitude of observable bodies in the cosmos. These significant bodies amount to 7 in total and are another cause for the 7 day week. And unless you believe that this is an arbitrary selection of ‘heavenly’ bodies that cannot possibly be the reason why we have a 7 day week, go no further than the names for those days that constitute a week.
The Day’s Names and Where They Come From
It should be said that the names of the days of the week in English come from Old English, while the names of the plants come from Latin. That accounts for the discrepancy in the names of the days.
Sunday — Not surprisingly, this day is named after the Sun.
Monday — Perhaps slightly less obvious, this day is named after the Moon
Tuesday — The planet which this day is named for is not immediately obvious, perhaps in English. But what about in French: Mardi. Easier? This day is named after Mars.
Wednesday — Like Tuesday, or most of the days in English, this day is not obvious. But again, let’s see in French: Mercredi. Got that one? This day is named after Mercury.
Thursday — I have noticed that many people know which God this day is named after, Thor. But not many know which planet that god corresponds to. French is useful to use, because it is closer to the language which we used to name the planets, Latin. One again in French: Jeudi. This one is named for Jupiter.
Friday — For this day I believe Spanish gives an easier clue than the French Vendredi, in Spanish: Viernes. This day is named for Venus.
Saturday — Perhaps another easy one, this day is named for Saturn.
Thanks For Reading!
