Names of the weekdays

In Cecil’s column explaining why there are seven days to a week, Cecil claims the following:

Does Cecil mean to say that the seven days of the week in ancient times were named after the planets? Or does he mean to say that that the seven days of the week are named after planets of ancient times.

If the second example is what he meant, I just want to point out that today only the Sunday and the Monday could possibly fall under this criteria. As for the other five days, although Saturn is a planet, it is more likely that Saturday was named after the Roman god. Tuesday, Wednesday, Thursday and Friday were named after Tir, Odin, Thor and Frey; gods of Norse mythology.

Could Cecil have been wrong? Shocking!


English           Latin            named for
Sunday          Solis dies         the sun
Monday          Lunae dies         the moon
Tuesday         Martis dies        Mars
Wednesday       Mercurii dies      Mercury
Thursday        Jovis dies         Jupiter
Friday          Veneris dies       Venus
Saturday        Saturni dies       Saturn

The New Shorter Oxford English Dictionary says that Saturni dies was named for the planet Saturn, not the god. I extrapolate from that the other days of the week in Latin were probably also named for the planets.

The days were named after the planets for astrological reasons. The Greeks were probably the first to name the days of the week after the planets, which in turn were named after gods. The Romans adopted the system and changed the names to those of their corresponding gods. See The Seven-Day Week and the Meanings of the Names of the Days

OP: Right – in ancient times the planets were named after the gods, and the days after the seven classical god/planets (incl. sun and moon in the geocentric universe); and “ancient times” for our Western Civilization, means Greece and Rome when there was no English language so Cecil is not wrong…

BTW – Spanish: domingo (Dominis Dies, Lord’s Day) lunes(Luna, Moon), martes (Mars), miércoles (Mercury), jueves (Jove), viernes (Venus), sábado (Shabbas[!!!])
The OP however does raise another question (Probably to GQ): how culturally universal is a seven-day week? And if so does it have a common origin or was it arrived at separately I mean, it does tend to roughly match the phases of the moon, an observable recurring phenomenon, but that does not necessarily mean it becomes a standard cyclical component of the calendar (e.g. the Maya, who clearly knew and understood the phases of the Moon)

Actually one could argue that your question is very suited to this forum. :slight_smile:
Why are there seven days in a week? Cecil says

Yep and in French: dimanche (dominis), lundi (lunae), mardi (martis), mercredi (mercurii), jeudi (jovis), vendredi (veneris), samedi (saturni).

Interstingly, in Iran the first day of the work week starts on Sunday=yekshanbeh (yek=one), Monday=dohshanbeh (doh=two), … Thursday=panjshanbeh (panj=five), Friday=jom-eh, and Saturday=shanbeh. The first five days of the week are simply the day number followed by the phrase “shanbeh” (don’t know what that means).

And Protuguese seems to have a mix of both: Sunday=domingo, Monday=segunda (second), Tuesday=terca (third), … Friday=seixta (sixth), and Saturday=sabado. [I only have basic knowledge of Farsi and Portuguese, so correct me if I’m wrong in any of the above.]

It’ll be intersting to know where these naming conventions come from: is the number-based system from Islam/Arabs, or is it just a result of Western civilizations imposing the 7-day week on these cultures?

The seven-day week is as Islamic as it is Christian.

Some Jews/Christians/Moslems have, over the years, objected to the pagan/planetary names, and attempted to substitute others. “The Lord’s Day” replaced “Sunday” in most non-Germanic Christian countries, but never became standard in English. The Puritans (and, I believe, the Quakers) attempted to introduce numeric designations for the remainder, too.

The Babylonians were the first to name days of the week after planets/gods. The Romans replaced the names with their own gods when Constantine borrowed the idea of a week. The idea of a week didn’t make it to Britain until the time of the Anglo-Saxon conquests, who took up some old Roman customs but kept their own religion and gods.


Planet             Ancient Planet-gods           Day Name
          Babylonian    Roman      Anglo-Saxon   (English)
Sun       Shamash       Sol        Sun           Sunday
Moon      Sin           Luna       Moon          Monday
Mars      Nergal        Mars       Tiw           Tuesday
Mercury   Nabu          Mercurius  Woden         Wednesday
Jupiter   Marduk        Jupiter    Thor          Thursday
Venus     Ishtar        Venus      Freya         Friday
Saturn    Ninurta       Saturnus   Saturn        Saturday

Source: Calendar: Humanity’s Epic Struggle to Determine a True and Accurate Year, by David Ewing Duncan (p. 56)

I believe this has been discussed before–to me, the most interesting thing is how the particular planets were assigned to particular days. Why Sun, moon, Mars, Mercury, Jupiter, Venus, Saturn?

If you order the planets (and sun and moon) in descending order of their (apparent) length of time of motion through the heavens, you get Saturn (29 years), Jupiter (12 years), Mars (almost 2 years), Sun (one year!), Venus (224 days), Mercury (88 days), moon (a month). Then, if you assign each planet to an hour, starting with the first hour of the day, and repeating the pattern for an entire week, you find that the first hour of each day is a different planet.

And, ta-da, they go like this: Saturn, Sun, moon, Mars, Mercury, Jupiter, Venus.

Actually, John W. Kennedy, in Judaism, the days of the week do not have names. They are simply called Yom Rishon (first day), Yom Sheini (second day) … Yom Shishi (sixth day). The seventh day (being Shabbos [Sabbath]) is the only one with a name.

Zev Steinhardt

Quite right. I had been thinking in general terms and forgot that this particular point doesn’t apply to Jews.

Although I wonder… What’s the current state of the matter in Israel?

In Israel, you can use either the Hebrew method (numbering), or you can refer to the days by their English names (Sunday, Monday, etc.) If you used the Arabic names you’d probably be understood as well.

Zev Steinhardt

One thing I’m still wondering–why did Saturn’s day keep its Roman name after all the other days got Germanic names? Did the Norse adopt Saturn as their own?