Astronomy’s roots in human culture run deep, and rarely more so than with nomenclature for our days of the week. Origins of the days of the week date to Sumerians around 5,000 B.C. The Romans revised them in A. D. 321. The Romans named weekdays after the “wandering stars” that moved through the sky and were thus “alive,” becoming candidates for worship as gods. At the time, seven such gods were known, which by coincidence matched the Biblical seven days of creation. Numerologists also favored the choice, pointing out that knowledge enters the head through seven openings. All seemed to be coming together with the number seven, as artists had seven primary colors and scientists seven metals.
The Sun gives us our day on which many of us relax and get ready for lots of work to come. Credit: NASA/Solar Dynamics Observatory
The seven days of the week, as defined in the ancient world, stacked up like this:
1. Sunday. Named for the Sun and associated with the Greek god Helios and the Roman god Solis. These were the gods of the daytime. Sunday was identified with the color yellow, the heart in the body, and the metal gold (aurum), with the chemical symbol Au.
2. Monday. Named for the Moon and associated with the Greek goddess Selene and the Roman goddess Luna. These were goddesses of the nighttime. Monday relates to the color blue, the brain in the body, and the metal silver (argentum), with the chemical symbol Ag.
3. Tuesday. Named for Mars and associated with the Greek god Ares and the Roman god Martis. (The word Tuesday comes from the Old English translation of the Latin Martis.) These were the gods of war. Tuesday correlated with the color red, the gall bladder in the body, and the metal iron (ferrum), with the chemical symbol Fe.
4. Wednesday. Named for Mercury and associated with the Greek god Hermes and the Roman god Mercuris. (The word Wednesday comes from the Old English translation of the Latin Mercurii.) These were gods of wisdom. Wednesday related to the color green, the lungs in the body, and the metal mercury (hydragyrum), with the chemical symbol Hg.
5. Thursday. Named for Jupiter and associated with the Greek god Dios and the Roman god Jovis. (The word Thursday comes from the Old English Thunor, an analog to the Roman and Greek gods.) These were gods of thunder. Thursday was identified with the color white, the liver in the body, and the metal tin (stannum), with the chemical symbol Sn.
6. Friday. Named for Venus and associated with the Greek goddess Aphrodite and the Roman goddess Veneris. (The word Friday comes from the Old English Frijjo, an analog to the Roman and Greek goddesses.) These were goddesses of love. Friday related to the color orange, the kidneys in the body, and the metal copper (cuprum), with the chemical symbol Cu.
7. Saturday. Named for Saturn and associated with the Greek god Kronou and the Roman god Saturni. These were gods of the harvest. Saturday correlated with the color violet, the spleen in the body, and the metal lead (plumbum), with the chemical symbol Pb.
Unfortunately, we never made it to my ultimate goal, the decimetric, or 10-day week. This would allow for a day of rest, a day of play, and a day of shopping, in addition to the 7 days we already have. And there would be three 10-day weeks per month. Somehow, though, I think I’m a little late in suggesting this.