On this day of Winter Solstice it seems appropriate to say something about the heavens and how we interact with them. If you already know why the days of the week are named what they are and why they appear in the order they do, I suppose you could skip this post. I knew for years that the days were named after planets, but never once wondered, for example, why Tuesday follows Monday. There are two separate though related explanations for the order of the days in the week, one far more interesting than the other. I'll cover both of them in this post. If I hadn't found it exciting at one point in my life to learn these things, I wouldn't bother you with them now. I hope to write more about them in the days or weeks to come. What I cover today is the ticket to things far more interesting. But, first we must know the days of the week.

Sunday is the easiest to start with. Sun + day = Sunday. Monday is Moonday. Tuesday… Here the problems begin. What possible connection could there be between Sun, Moon and Tuesday? Tuesday is named after the Norse god Tyr, but before that will make sense, we must know something about the classical planets.

Before the invention of the telescope — Galileo made the first scientific use of the telescope, but its fairly certain he did not invent it — there were seven visible objects that moved among the stars. These were the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. No Uranus, no Neptune. These are visible only through telescopes more powerful than Galileo's. No Pluto. Poor Pluto is no longer considered to be a planet. Of course, there were comets, but these were more like occasional intruders. So, while it may seem strange to call the Sun and Moon planets, they are exactly that — things that move (from an Earth-centered perspective) against the background of the stars.

The names Mercury, Venus, Mars, Jupiter, and Saturn should sound familiar. They are the names of Roman gods, or the Latinized versions of Greek gods. You learned about them in elementary school. The Latin for sun and moon, by the way, is sol and luna . The Romance languages, the languages that grew out of Latin, make it much easier to see the planets, or their names, in the names of the days of the week. Everyone knows Mardi Gras (Fat Tuesday). In Latin, Tuesday is dies martii, the day of Mars, which is easily seen in the French word mardi. There are similar derivations for the other days. But to get from mardi to Tuesday takes one additional step. The Roman historian Tacitus, in his Germania, provided a list of correspondences between the Norse gods and those that evolved nearer the Mediterranean. He did so in the belief or knowledge that the same principles that caused one also caused the other. He determined that the Norse god Tyr, a god of combat, was the equivalent of Mars. In Old English, Tyr was Tiw. From Tiw comes Tuesday. Thus, Tuesday is Mars day. That's a long way around, but that's how it is.

In the same manner, Wednesday is Norse Oðinsdagr, which in Old English became Wōdensdæg and is therefore, following Tacitus, Mercury's day. Thursday is Thor's day, Thor being Jove or Jupiter. Friday comes from Freyjudagr, by way of frīgdæg, Freyja and/or Frige being Venus. Which brings us back to Latin. Saturday is Saturn's day. So, even if it's no longer apparent, even in English the days are named after the planets.

The next order of business is the order of the planets, not the order of the days, but the classical order of the planets themselves. This seems tedious, but first we must know the planets and then the days. In school, I learned that the order of the planets was Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. I'm sure you learned exactly the same. Of course, that's their order from the Sun. It also neglects the Moon. In ancient times, distance from the Sun was poorly understood, if understood at all. Once we accept the Sun as planet, it's difficult to imagine it not being the first planet on the list. It's certainly the most prominent. But, the planets were listed by speed, not prominence. Not speed in the sense of velocity, exactly, but by the quickness of their cycles.

The Moon in this system is the fastest thing in the Universe. It completes one lunar cycle in only twenty-eight days. It returns to the same place in the heavens after passing through all the constellations in roughly twenty-eight days, or the same place plus one twelfth, give or take. It's the roughly and the give or take that keep things interesting. If you object that the Sun goes around the Earth in a single day, you're neglecting to realize that the Sun and everything else goes around in the same period. The Sun's cycle is one year. It takes a year to move through the months and finally return to its starting place.

Mercury is very difficult to observe because of its proximity to the Sun. It appears somewhat randomly at sunset or sunrise close to the horizon and then disappears into the light or sinks out of sight. Still, it was very well known even in prehistoric times. It's cycle is a hundred and some days. Because it's an interior planet, i.e. between us and the Sun, its cycle is defined as returning to the same place in relation to the sun, not the same place in relation to the stars. Mercury is the second fastest.

Venus, also an interior planet, is perhaps the most spectacular of the bunch. It alternates between morning and night star. At it's brightest, only the Sun and Moon rival it. It rises inconspicuously into the evening sky near sunset over a period of months. Eventually, it shines very brightly. It's the star people normally wish upon. Then, in a period of days, it falls from the sky and is seen no more. Its fall is the source of many myths. After passing near the Sun, it makes an equally spectacular rise into the morning sky where, over a period of months, it gradually disappears. It goes behind the Sun. Although its velocity is greater than the Earth's, the Earth is racing around in the same direction, so the apparent cycle of Venus is greater than one year. Venus is the third fastest.

We skip the Earth, because the Earth is the center of everything. It stays put while all else revolves, rotates or retrogrades. The periods of the outer planets, Mars, Jupiter and Saturn, are very roughly two, twelve and twenty-eight years. If the skies were clear tonight — it's raining at this particular center of the universe — I could admire the conjunction of the crescent Moon and Jupiter. Something's always going on up there. So, we now have our corrected list of planets. It reads, Moon, Mercury, Venus, Sun, Mars, Jupiter, and Saturn. If we place them on the Wheel of the Planets, they should look something like this:

Starting with the moon on the bottom left and moving clockwise, each planet in succession is "slower" than the one preceding it — until the jump from Saturn to Moon where the wheel starts over again. Now, replacing the signs with the days of the week that represent them and connecting the dots to form a seven pointed star, we end up with the following:


Long before you learned the names of the gods in elementary school, you learned to make five-pointed stars without lifting the point of your pencil. Seven-pointed stars are the same thing with different angles. Starting from the Sun, or Sunday, draw a line to Monday. From Monday, continue the line to Tuesday, then Wednesday, Thursday, Friday, Saturday, and back again to Sunday. You have just drawn a seven pointed star. You have also discovered, whether you yet realize it or not, the secret to the order of the days of the week. What seemed random and meaningless turns out to be complicated, but precisely ordered. You can do the same thing in a very laborious and uninteresting way. You can start with the first hour of the day and call it Moon. After that, you can work your way through the planets three times and then add three more. You will have managed to go from Sunday to Monday and can continue in this manner throughout the week. The Babylonians did something like this to determine which planet ruled each hour, but if elegance has anything to do with truth, they discovered the seven-pointed star first and then copied out the rest.

There it is, the answer to why Tuesday follows Monday. I hope this will be helpful. I hope it will prompt you to see things somewhat differently. It's a truism that the marvelous lies behind and below the surface of everyday things. It's always there, always waiting. I would only add that if you know how and where look, even Mondays can be delightful.

Happy Winter Solstice

May your days grow longer and your heart be full.