The days of the week are named after the stars. There are many, many translations of this in different languages, but here, for my purposes, I will use the rough Latin translation:
Sunday: Dies Solis = The Day of the Sun
Monday: Dies Lunae = The Day of the Moon -- me, being born on a Moonday, or a Moodday, this is a very special day for me.
Tuesday: Dies Martis = The Day of Mars
Wednesday: Dies Mercurii = The Day of Mercury
Thursday: Dies Iovis = The Day of Jupiter -- me, being a Sagittarius and my ruling planet being Jupiter, this is a very special day for me.
Friday: Dies Veneris = The Day of Venus
Saturday: Dies Saturni = The Day of Venus
Now, that was fun!
Do you also know why the days are named in that particular order? They are not in the same order in which the planets are found. Incidentally the method was given first by an Indian sage/mathematician called Parashar.
No, I do not know why. Why?
Parashar (circa 1600 BCE) had a fairly good idea about the location of the planets except for one mistake. He placed Venus nearest to the sun instead of Mercury. He proceeded to divide a day into 24 equal parts, each one called a Hora. Thereafter he proceeded to arrange the planets in a circular formation having Sun and Saturn at the two ends with Jupiter and mars on one side and Venus, mercury and Moon on the other. I have gven a rough diagram below:
Sun ..................................... Saturn
Starting from Sun, a Hora is allotted to each planet continuously. So on day One, the First Hora belongs to the Sun, the second one to Venus, third to mercury and so on. This is Sunday. This way the first, eighth, fifteenth and 22nd hora would belong to the sun. 23rd and 24th would belong to venus and mercury at which point Day One will end. Therefore the first Hora of Day Two would then belong to the Moon. That will be Monday or the day of the Moon. On this day the the first, eighth, fifteenth and 22nd hora would belong to the moon and the 23rd and 24th would belong to Saturn and Jupiter. Day 3 will then begin with Mars which is Tuesday and so on.
PS: I use the terms Day and Planets (Graha) in the sense in which they are understood in Indian astronomy. Accordingly a day is always the time from sunrise to sunrise and not midnight to midnight as is the modern practice. Again a Graha (planet) is a heavenly body whose movements/change in position vis-a-vis the earth is discernible. It may be a planet or a star or a satellite according to modern science.