1. How Did the Planets End Up Naming the Days of the Week?
The seven days of the week were once tied to seven bright objects that move across the sky: the Sun, the Moon, and five planets that can be seen without a telescope. Friday's object is Venus, which can shine as the bright "evening star" or "morning star" at different times of the year. In Latin, Friday was dies Veneris, the "day of Venus," and the Romans connected the planet with their goddess of love. [6] The French vendredi, the Italian venerdì and the Spanish viernes are still close relatives of that Latin phrase. [3]
Nobody knows exactly where the planet-day idea began. It took shape in Hellenistic astrology, and it may have older roots in Babylonia. [4] The Roman Empire gradually adopted the seven-day week during the first to third centuries CE, and by the fourth century it was in wide use. [6]
English once listed the planet-days too. An Old English handbook, Byrhtferth's Enchiridion, says that the Romans and the English each gave the days the names of the planets, and that the sixth day went to Venus. [1] So the question for this article is a sharp one: if English speakers once knew Friday as Venus's day, where did Venus go?
2. How Did Venus's Day Become Frigg's Day in English?
The usual explanation is that people translated the day's name, and in doing so replaced the goddess. Speakers of the early Germanic languages, the ancestors of English, German, Dutch and the Scandinavian languages, matched Roman gods with gods of their own who seemed to play a similar role. Scholars call this habit interpretatio germanica, the "Germanic interpretation." [2] [3]
For Venus, the Germanic match was Frigg, a goddess linked with marriage, motherhood and foresight. Her name appears in several early Germanic languages, and the name is traced to the Proto-Germanic word for "free," which in a clan society could also mean "related." [3] The Old English phrase Frīġedæġ, "Frigg's day," was a word-for-word copy, or "calque," of the Latin dies Veneris. It later turned into Middle English Friday. [2] [3]
The same swap shows up all over the Germanic family: Dutch vrijdag, German Freitag and Danish fredag are cousins of Friday. [2] English Tuesday, Wednesday and Thursday went through similar swaps, with Germanic gods standing in for Mars, Mercury and Jupiter. [5]
We can't say exactly when this happened. The swap came after the Germanic peoples met the Roman week and before they converted to Christianity, a span of several centuries, and no single year can be named. That is a historian's estimate, not a recorded date.
3. Was Friday's Goddess Frigg or Freyja?
You may have seen Friday explained as "Freya's day." Freyja is a goddess in Norse mythology, and her name is easy to mix up with Frigg's. The two are often confused for a good reason: scholars still debate whether they were once the same goddess. Frigg is known from several West Germanic peoples, but Freyja is attested only in Scandinavia, and the surviving evidence from before the Viking Age is thin. [3]
For English, the standard explanation is Frigg: Old English Frīġedæġ goes back to the Germanic form of her name. [2] [3] Old Norse did have a rare name, Freyjudagr ("Freyja's day"), which replaced the first part of the older word. [3] So both goddesses turn up in the story of Friday, but in different places. That is why some sources say Friday honors Frigg and others name Freyja. Whenever you read one of these claims, check which language the writer means.
4. Why Does Venus's Day Come Sixth in the Week?
The week's order isn't the order of the planets in the sky, and it isn't a ranking by brightness either. In the ancient Greek and Roman model, the seven objects were arranged from farthest to nearest: Saturn, Jupiter, Mars, the Sun, Venus, Mercury, the Moon. [4] Ancient writers, including a Roman historian named Cassius Dio, explained the week with an astrological rule: each of the 24 hours of a day was "ruled" by the next object on that list, round and round. The object ruling a day's first hour gave the day its name. [4] [5]
Because 24 divided by 7 leaves a remainder of 3, each new day's first hour lands three places further along the list. Starting with the Sun, you get the Moon, Mars, Mercury, Jupiter, Venus, Saturn, and back to the Sun. That is exactly Sunday to Saturday, and it puts Venus's day on Friday. [4] A Japanese university lecture note adds a neat detail: any number that leaves a remainder of 3 when divided by 7 would do, and 10 is the smallest. [5]
This is a story from ancient astrology, and it explains the order well. It doesn't explain why people chose a seven-day week in the first place. That part of the history is still debated. [6]
5. How Did Japan End Up with a Venus Friday Too?
Japan reached the same idea by a completely different road. Japanese weekday names use characters for the Sun, the Moon and five classical planets, so Friday is 金曜日 and Venus itself is 金星. According to a lecture note from Kyoto College of Graduate Studies for Informatics, the seven-day week did not come to Japan from Europe: the monk Kūkai (774–835) brought it back from Tang China in the early 9th century, and the weekdays are written in an astrological text. [5]
The result is a nice comparison. Both day names are tied to Venus, by different routes. English replaced the planet with a goddess, while Japanese kept the planet in the character 金. [2] [5]
6. Can You Rebuild the Order of the Week with Pencil and Paper?
You can check the "24 hours" rule yourself. Write the seven objects in a circle: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon. Say the first hour of Saturday belongs to Saturn. Count 24 places around the circle, one per hour, and see where you land. That object rules the first hour of the next day. Repeat it for seven days and compare your list with the calendar on your wall.
Then try the language side: look up the word for Friday in another language. Does it contain a planet, a goddess, or a number? If you want to go deeper, the Oxford English Dictionary entry for Friday and the Kyoto lecture note listed below are good places to start.