Why Were The Days of the Week Named After The Solar System?

A long time ago in human history, people thought that Earth was flat, and at the universe's center. They believed that seven members of the solar system forever circled around us—see graphic to the right, or view one from Censorinus - Sur le jour natal.

Some Mediterranian peoples also believed that each hour of the day was ruled by either the Sun, Moon or one of five then-known planets, all of which were thought of as gods. The sequence in which they thought hours were governed was the inverse order of distance they believed those solar system objects to be from Earth.

During this time, Egyptians thought that the most distant was Saturn, shown at the bottom of the graphic above. They thought that the order of closer members (shown counterclockwise following Saturn) was Jupiter, Mars, Sun, Venus, Mercury and closest, the Moon. So they believed that the first hour was ruled by Saturn, the second by Jupiter and so on.

Egyptians also believed that after each seven hours the order in which these objects ruled was repeated, so it started again with Saturn.

According to those ancient Egyptians, the planet that ruled the first hour also governed the entire twenty-four hour period, and gave its name to that day. The first (and also the 8th, 15th and 22nd) hours of the first day were sacred to Saturn, the 23rd to Jupiter, the 24th to Mars and the first hour of the next day to the Sun. Therefore, they believed that the first day was ruled by and named after Saturn (Saturday) and the second was ruled by (and named after) the Sun (Sunday).

Egyptians once divided all twelve 30-day months (of their 360-day calendar year) into three 10-day weeks in the same manner as Greeks of the same period. The epoch at which planet worship caused them to change its length to seven days is not known, but it must have been over twenty-five hundred years ago because Herodotus, writing in his History during the 5th century B.C. said: "Here are some other discoveries of the Egyptians. They find...each day belongs to a god..."

Adherents of the cult of Sin at Harran, who were known as Harranians or Sabeans by Arabic and Syrian authors, named their days after the same solar system members as Egyptians and Persians. Like Hebrews and many other peoples, they considered the one named after Saturn to be the seventh day, so they began their week with a day named after the Sun. All seven days were named after solar system members in the same order as they were in Egypt.

It is interesting to note that these exact same solar system objects, and in the same sequence, were also used to name days in ancient India, Tibet and Burma. This is also true of names for Japanese days of the week, but the custom there has been traced back only a thousand years.

Roman soldiers stationed in Egypt became accustomed to the pagan seven-day week and began to introduce it into their own homeland to replace their eight-day marketing week. Octavian (Caesar Augustus) and succeeding Roman rulers permitted this practice but it wasn't made official until the emperor Constantine took that step in A.D. 321.

English names for days of the week are derived from Anglo-Saxon names for those same seven heavenly bodies that were revered by ancient peoples. Compare those English and Anglo-Saxon day names in the table below. Other similarities between day and "planet" names in various countries can be observed there.

I thought the days of the week were named after some of the members of the Norse pantheon. well, I suppose it must vary by culture.