Jupiter = Zeus-pater = gods' father, english language days of week and month names etymology

god is from deus/dios and deus is from Zeus day/sky. Jupiter is Zeus-pater = gods' father. (So I guess Saturn is the grandad! :) ).

Love how miscellaneous the naming of the days and months is! :) A facebook comment thread with computer programmers not surprised how messy the naming scheme got! E.g. november, the ninth month is now the 11th month, mix of old gods and roman emperors and numbers in the day and month names.

I found the Zeus-pater = Jupiter recently in the cartoon history of the universe II by Larry Gonick.

https://www.penguinrandomhouse.com/books/69151/the-cartoon-history-of-the-universe-ii-by-larry-gonick/9780385420938/

https://www.amazon.com/Cartoon-History-Universe-Volumes-8-13/dp/0385420935

TLDrR; summary from Dave Neary on the facebooks "Sun day, Moon day, Tiwe's Day (also, in latin languages, Mars's day), Wodin's Day (Mercury's Day in Latin languages), Thor's Day (Jupiter's Day), Freia's Day (Venus's Day), Saturn's Day; Janus's month, purification month, Mars's month, April's month (origin uncertain?), Maia's month, Juno's month, Julius's month, Augustus's month, the seventh month, the eight month, the ninth month, the tenth month. Pretty varied bunch."
Janus is Roman god of beginnings. Februa is a purification feast.

https://en.m.wikipedia.org/wiki/Jupiter_(mythology)
https://en.m.wikipedia.org/wiki/Saturn_(mythology)

https://en.m.wikipedia.org/wiki/Mars_(mythology)

https://en.m.wikipedia.org/wiki/Mercury_(mythology)

https://en.m.wikipedia.org/wiki/Janus
https://en.m.wikipedia.org/wiki/January
https://en.m.wikipedia.org/wiki/Februa
https://en.m.wikipedia.org/wiki/February
https://en.m.wikipedia.org/wiki/Mars
https://en.m.wikipedia.org/wiki/March
https://en.m.wikipedia.org/wiki/April
https://en.m.wikipedia.org/wiki/Maia
https://en.m.wikipedia.org/wiki/May
https://en.m.wikipedia.org/wiki/Juno
https://en.m.wikipedia.org/wiki/June
https://en.m.wikipedia.org/wiki/Julius_Caesar
https://en.m.wikipedia.org/wiki/Augustus_Caesar
https://en.m.wikipedia.org/wiki/August
https://en.m.wikipedia.org/wiki/September

Octavius ?

https://en.m.wikipedia.org/wiki/October

https://en.m.wikipedia.org/wiki/November

https://en.m.wikipedia.org/wiki/December

http://www.calendar-origins.com/calendar-name-origins.html

"Calendar - from Middle English calender, Latin calendarium (account book). The Romans called the first day of each month Kalendae, or calends. Debts were due on this day, so books to track payments were called calendarium from which we get our modern day calendar."

Calendar Name Origins - Names of Months

January - ME Januari(us), OE Januarius, translation of Latin Januarius, named after JANUS, god of beginnings.
February - ME OE Februarius from Latin Februarius, named for Februa, the feast of purification.
March - ME March(e), from Latin Martius, (month of) Mars.
April - ME Averil, OF Avril, Latin Aprilis mensis (month). The name may derive from the Greek goddess of love, Aphrodite.
May - ME OE Maius, Latin Maius mensis (month), from the Greek Maia, goddess of spring (growth).
June - ME Jun(e), OE Iunius, from Latin mensis Junius, named after the goddess Juno, Queen of the gods.
July - ME Julie, OE Julius, from Latin Julius (Caesar) after whom it was named in 44 BC. The original name was quintilis, fifth month in the early Roman calendar.August - ME OE Agustus from Latin Augustus (Caesar) 8 BC. The original name was sextilis, sixth month in the early Roman calendar.
September - ME Septembre from Latin September, seventh month in the early Roman calendar
October - ME OE from Latin October, eighth month in the early Roman calendar
November - ME OE from Latin November, ninth month of the early Roman calendar, from novem NINE
December - ME Decembre from OF and Latin December, tenth month of the early Roman calendar (decem TEN + membri from mens MONTH + ri suffix).

ME = Middle English
OE = Old English
OF = Old French
OHG = Old High German

This has more good info: (text below from here)

https://www.google.com/amp/s/amp.livescience.com/45432-days-of-the-week.html

Why 7 days a week? The Babylonians again :)

(Babylonians with segsagecimal 60 based counting systems, 360 degrees in a circle, 60 seconds in a minute, 60 minutes in hour, 12*2=24 hours in day)

The seven-day week originates from the calendar of the Babylonians, which in turn is based on a Sumerian calendar dated to 21st-century B.C. Seven days corresponds to the time it takes for a moon to transition between each phase: full, waning half, new and waxing half. Because the moon cycle is 29.53 days long, the Babylonians would insert one or two days into the final week of each month.

Jewish tradition also observes a seven-day week. The book of Genesis (and hence the seven-day account of creation) was likely written around 500 B.C. during the Jewish exile to Babylon. Assyriologists such as Friedrich Delitzsch and Marcello Craveri have suggested that the Jews inherited the cycle of seven days from the Babylonian calendar.

The Romans also inherited this system from Babylonian tradition, though they didn’t begin using it until the instatement of the Julian Calendar in the first-century B.C. Up until this point the Romans had used the “nundinal cycle,” a system they inherited from the Etruscans. This was a market cycle of eight days labeled A-H. On market day, country folk would come to the city and city dwellers would buy eight days' worth of groceries. By the time the seven-day week was officially adopted by Constantine in A.D. 321, the nundinal cycle had fallen out of use.

The Romans named the days of the week after their gods and corresponded to the five known planets plus the sun and moon (which the Romans also considered planets). To this day, all Romance languages (most familiarly Spanish, French, and Italian) still bear the mark of Roman day names, the exception being Sunday, which now translates to “Lord’s Day” and Saturday, which translates to "Sabbath."

Day	Planet	Latin	Spanish	French	Italian
Monday	Moon	Dies Lunae	lunes	lundi	lunedi
Tuesday	Mars	Dies Martis	martes	mardi	martedi
Wednesday	Mercury	Dies Mercurii	miércoles	mercredi	mercoledì
Thursday	Jupiter	Dies Jovis	jueves	jeudi	giovedi
Friday	Venus	Dies Veneris	viernes	vendredi	venerdì
Saturday	Saturn	Dies Saturni	sábado	samedi	sabato
Sunday	Sun	Dies Solis	domingo	dimanche	domenica

Germanic adaptations

The English words for each day bear remnants of Roman tradition, but they have been filtered through centuries of Germanic and Norse mythos. The Germanic people adapted the Roman system by identifying Roman gods with their own deities.

Sunday comes from Old English “Sunnandæg," which is derived from a Germanic interpretation of the Latin dies solis, "sun's day." Germanic and Norse mythology personify the sun as a goddess named Sunna or Sól.

Monday likewise comes from Old English “Mōnandæg,” named after Máni, the Norse personification of the moon (and Sól's brother).

Tuesday comes from Old English “Tīwesdæg,” after Tiw, or Tyr, a one-handed Norse god of dueling. He is equated with Mars, the Roman war god.

Wednesday is "Wōden's day." Wōden, or Odin, was the ruler of the Norse gods' realm and associated with wisdom, magic, victory and death. The Romans connected Wōden to Mercury because they were both guides of souls after death. “Wednesday” comes from Old English “Wōdnesdæg.”

Thursday, "Thor's day," gets its English name after the hammer-wielding Norse god of thunder, strength and protection. The Roman god Jupiter, as well as being the king of gods, was the god of the sky and thunder. “Thursday” comes from Old English “Þūnresdæg.”

Friday is named after the wife of Odin. Some scholars say her name was Frigg; others say it was Freya; other scholars say Frigg and Freya were two separate goddesses. Whatever her name, she was often associated with Venus, the Roman goddess of love, beauty and fertility. “Friday” comes from Old English “Frīgedæg.”

As for Saturday, Germanic and Norse traditions didn’t assign any of their gods to this day of the week. They retained the Roman name instead. The English word “Saturday” comes from the Anglo-Saxon word “Sæturnesdæg,” which translates to “Saturn’s day.”