What do the names of the days of the week in Spanish mean?

Lunes (Monday) I get, Luna being the word for Moon
Martes (Tuesday)??
Miercoles (Wednesday)??
Jueves (Thursday)??
Viernes (Friday)??
Sabado (Saturday) = Sabbath
Domingo (Sunday) = [something akin to] Lord’s Day

Martes : Mars’ Day
Miercoles : Mercury’s Day
Jueves : Jupiter’s Day
Viernes : Venus’s Day
Sabado : Sabbath

It’s basically the planets (as understood way back) and the same as French (more or less)

SP/FR/Meaning/
Lunes/Lunedi/Moonday
Martes/Mardi/Marsday
Miercoles/Nercredi/Mercuryday
Jueves/Jeudi/Jupiterday
Viernes/Vendredi/Venusday

It splits for the weekend:
Sabado/Samedi
Domingo/Dimanche

English picks up the rest of the planets Saturnday and Sunday.

We might as well do German:
Montag, Dienstag, Mittwoch, Donnerstag, Freitag, Samstag or Sonnabend, Sonntag.

It’s based on deities. The Romance languages, such as French and Spanish, use the Latin names of Roman gods for the days of the week; the Germanic languages, such as English and German, use the Germanic, i.e. Norse, equivalents for these Roman gods. For instance, Jupiter, the supreme god, is identified with the Norse Thor (aka Donar), and that gives you Thursday and Donnerstag.

Sábado and Domingo are exceptions. Sábado is the Hebrew sabbath, and domingo is the Lord’s day.

The English names have the same derivation, except that we use the “equivalent” Germanic gods for some of them:

Tuesday = Tiw’s day
Wednesday = Woden’s (or Odin’s) day
Thursday = Thor’s day
Friday = Frig’s day

See the Wikipedia article:

From the dative declensions, Martis, Mercurii, Jovis and Veneris, filtered through various drifts in prounciation and dropping the “day” designation which other languages do keep.

That Spanish did not borrow any Arabic or Berber names for our calendar designations in spite of 700 years of presence or contact may have been helped by how it was the Church that kept up the calendar during that time for the Romance-speakers.

In Japanese they are all based on the solar system:

Sunday/nichiyobi (日曜日=太陽/←”taiyo”/”sun”)
Monday/getsuyobi (月曜日=月/←”tsuki”/“moon”)
Tuesday/kayobi(火曜日=火星/←”kasei”/”mars”)
Wednesday/suiyobi (水曜日=水星/←”suisei”/“mercury”)
Thursday/mokuyobi(木曜日=木星/←”mokusei”/jupiter”)
Friday/kinyobi (金曜日=金星/←”kinsei”/“venus”)
Saturday/doyobi (土曜日=土星/←”dosei”/“saturn”)

(listed with Sunday first as is commonly done in Japan.)

Are the planets assigned to deities in the Japanese language? Or are they just the names the Japanese came up with for the dots in the sky, irrespective of any connection to gods/goddesses?

According to this Japanese website, they are assigned/based on the deities.

At the bottom of that site’s page, they give a link that refers to the Latin origin of the names:

https://eco.mtk.nao.ac.jp/koyomi/wiki/CDD7C1C72F1BDB5B4D6A4C8A4CFA1A92FCDCBC6FCA4CECCBEC1B0.html

Even though I’m basically fully fluent in Japanese, both pages are a bit more detailed than I’d like to translate for SDMB. If you are interested enough, maybe you can use a site or ChatGPT to translate it for you,

N/M  

In Polish, Sunday is niedziela which translates to “no work.” (Nie is no, dziala connotes a bit more like functioning.)
Remember, it’s a very Catholic country, and working on the Lord’s day is forbidden by a certain big, thick book.

Monday is poniedzialek which quite literally translates to … “after no work.” Pretty straightforward.

Wednesday is sroda which comes from the word for “middle.” Makes sense.

Thursday is "czwartek* which comes from the word for “four” or “fourth.” Okay.
Friday is “piatek” which comes from the word for … you guessed it, “five” or “fifth.” Pretty predictable!

When salt-of-the-earth peasants who adhere strictly to Catholicism do, well, language things, that’s what you’re gonna get!

P.S. apologies that certain special characters are missing, Polish has letters (well, marks added to letters that English readers would recognize) that are not included in the above post.

Portuguese, otherwise often quite similar to Spanish, also has sábado and domingo like Spanish but follows a simple numbering of the days, counting from Sunday: Monday is second-day, Tuesday is third-day etc, all the way through Friday, sixth-day.

What’re Tuesday and Saturday in Polish?

I’d think it can’t be a coincidence that those are the same planets/gods assigned in English and for the most part French and Spanish. Even the German names that are planets/gods match.

Because they all ultimately got them from the Romans. The Romans started adopting the seven-day week from the Jews around the time of the early Empire (long before Christianity, BTW), and from there the concept spread slowly to much of the rest of the world over the next 1000 years.

Incidentally, in Hebrew the days of the week are named after what’s they’re called in the Bible, in Genesis Chapter 1: First Day, Second Day, Third Day, Fourth Day, Fifth Day, Sixth Day, Sabbath.

According to Wikipedia, Japan got its days of the week from China, which adopted the western naming scheme from the Manicheans in the 8th century.

(Now that the question has been answered…)

Thanks for making me learn a little about Manichaeism. Fascinating! Founded by an Iranian Jew (probably) around 250 BC…briefly a rival to Christianity as polytheism declined in the late Roman Empire (so it’s ironic it later brought the Roman gods as days/planets to China)…flourished among the Uighurs of western China (who are today persecuted for their Muslim faith), and regarded by many Han Chinese as a weird form of Buddhism (and brutally suppressed, along with Buddhism, for a period in the 800s AD…)

I had no idea.

Tuesday = Wtorek. Which means ‘second’, but an ancient form of second that isn’t used anymore except in words that relate to ‘repeat’

Saturday = Sobota. I think you can work this one out.

And isn’t “Sabbath”, itself, derived from a word for “Seventh”?