How did the days of the week get their names, and how was the order of the days established?

The English day names are Old English adaptations of ancient Roman day names, which themselves may have been adaptations of even more ancient systems of naming and ordering days, dating back to the ancient Babylonians or even earlier. But no one knows for sure who established the original naming system or why.

The following chart shows how our day names correspond to the day names of our French and Norwegian brother and sister cultures, and to our parent Latin culture:

The most likely explanation for this system of naming is that the day names have astrological associations, being named after the Sun (Sunday), the Moon (Monday), and the planets. In order to understand more fully why the days are named the way they are, and why they come in the order they come in, it is necessary to understand a bit more about how astrology was practiced in ancient times.

Today, scientists tell us that there are eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune, and Uranus. They used to say nine planets and included Pluto, but recently the International Astronomical Union decided that Pluto no longer counts as a planet. Some astronomers think this was a bad decision and may try to reverse it, but that is another story. In ancient times, people who studied the heavens counted seven planets. Ancient peoples did not yet know of the existence of Neptune, Uranus, or Pluto, because telescopes had not been invented and these bodies cannot be seen with the naked eye. Most ancients also believed the Earth to be the center of the Universe, and they did not count it as a planet either. On the other hand, because the Sun and the Moon moved through the heavens independently of the seemingly fixed stars, these were counted as planets. Our word "planet" comes from the ancients, and means simply "wanderer." Thus, for the ancients, the seven planets were Mercury, Venus, Mars, Jupiter, Saturn, the Sun and the Moon.

Ancient astrologers, like modern astronomers, studied the movements of the celestial bodies very carefully. But the ancients believed the movements of the stars and the planets to reflect much more than mere physical laws. The movements of the celestial bodies reflected a grand order which ruled everything under the stars. Only by understanding the order of the heavens, would it be possible for humans to align themselves with that divine pattern and thus hope to achieve prosperity, health, and wisdom. The ancients saw divine significance and divine correspondences in all things, and they used mathematics and numbers as tools to understand the interrelationships between the bodies of the heavens and life down here on earth.

In ancient Europe the movements of the stars and planets were attributed to a series of spheres surrounding the earth and rotating at different speeds. The first sphere was the sphere furthest from Earth, the one closest to God, and was believed to be responsible for setting all the other spheres in motion. This sphere was invisible, and it was referred to as the "Primum Mobile" or "First Mover." The second sphere, just beneath the Primum Mobile, was the sphere of the fixed stars, the sphere belonging to the constellations. The seven spheres below the second sphere belonged to the seven planets. Because Saturn was the slowest moving of the planets, it was believed to belong to the planetary sphere closest to the fixed stars and the Primum Mobile, so Saturn belonged to the third sphere. Jupiter, the next slowest moving planet after Saturn belonged to the fourth sphere. Mars, the next slowest, belonged to the fifth sphere, and so on down to the Moon, the fastest moving celestial body, which occupied the ninth and lowest sphere, closest to the Earth. To summarize, the planetary spheres were ordered as follows:

sphere	planet	symbol
3rd	Saturn
4th	Jupiter
5th	Mars
6th	Sun
7th	Venus
8th	Mercury
9th	Moon

A diagram of how the ancients imagined the cosmos to be organized looks something like this:

Each of the planets was named after and believed to correspond to a god who ruled various aspects of life here below on Earth. For example, Venus ruled over love, Mars ruled over war, Jupiter over the search for wisdom, and so on. The phases of the moon were very important to the ancients, who observed that the moon went through roughly twelve complete cycles in the course of a year. The fixed stars were thus divided into twelve regions known as the "zodiac," through which the movements of the planets were charted (Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces). Each of these twelve regions was also believed to correspond to certain elements or aspects of life down here below. For instance, the region of the zodiac assigned to the constellation Virgo was believed to influence illness and health, the region of the zodiac assigned to the constellation Cancer to influence hearth and home, etc. Particularly important to know, if we wish to understand the day names, is the ancient idea that each region of the zodiac was ruled by one of the seven planets. For example, Saturn ruled Capricorn and Aquarius, Jupiter ruled Sagittarius and Pisces, Mars ruled Aries and Scorpio, and so on.

Because the ancients saw all aspects of life here below on Earth as having a direct correspondence to the divine laws governing the movements of the stars, the units by which time on Earth was measured were deliberately divided and ordered so as to correspond to the order observed in the Heavens. Just as the zodiac was divided into twelve distinct regions through which the sun travelled in the course of a year, each day -- the period of time in which the sun travelled from the eastern horizon to the western horizon -- was also divided into twelve periods or hours. The night was similarly divided into twelve hours. Just as each of the twelve signs of the zodiac was ruled by one of the seven planets, so each of the twelve hours of the day and the twelve hours of the night was assigned to one of the seven planets. The order in which hours were assigned to the planets was the same as the order of the heavenly spheres. Thus, the hour of Saturn was followed by the hour of Jupiter, the hour of Jupiter was followed by the hour of Mars, the hour of Mars was followed by the hour of the Sun, etc.

Now suppose that the first hour of a given day -- the first hour after dawn -- is the hour assigned to Saturn. With each night and each day divided into twelve hours, and with each hour ruled by one of the seven planets in the order of the seven planetary spheres, how many days will it take before the hour of Saturn is the first hour of the day again? The answer is seven days, as the following table should make clear:

The first hour after dawn was considered the ruling hour of the day, and was the hour after which each day was named. When one compares the planetary order of the days in the above chart to the English day names, it should become obvious that the standard order of the days of the week is not random at all, but follows from the very ancient astrological practice of naming hours after planets in the order of the planetary spheres. The movement of the planets thus literally determined the order of the days.

Most people today simply take the names of the days for granted, and very few have any idea how these names might relate to astral phenomena. After all, in our world the main significance of the weekly calendar is for business, law, and finance, which need not consider what a day is named or why, but simply whether banks and government offices are open or closed on that day. We no longer track the astrological correspondences of the hours, so the obvious connection between the order of the day names and the order of the heavens is all but forgotten. Most people who are aware of the astrological correspondences of the day names tend to think of astrology as a pagan fortune-telling system having little relevance today. But a deeper understanding of the likely connection between the names of the days of the week and ancient belief systems might remind us of an ancient religious sensibility that does bear resemblance to a basic principle of most of today's world religions. Namely, that the order of the days should be established so as to enable humans better to emulate here below the divine order established above. "To every thing there is a season and a time to every purpose under the heaven." And "Thy will be done, on earth as it is in heaven."