Days of the Week
First published 27 Aug 1993 on Alt.Pagan

There has been some discussion on Alt.Pagan about the origins of the names of the days of the week, and whether of not it was a Church thing or a Jewish thing or what. The Romans traditionally had an 8 day week, ending in a market day. The OT would suggest that the 7 day period is related to the Sabbath. However, there is another explanation, which should at least be considered.

The Roman names of the Gods were assigned to the various days, not specifically because of the Gods, but rather because of the Planets, referring to the Planetary Week.
 
 

  Regent/Saturn's Day Sun's Day Moon's Day Mars's Day Mercury's Day Jupiter's Day Venus's Day
Saturn  1  8 15 22     5 12 19  2  9 16 23     6 13 20  3 10 17 24     7 14 21    4 11 18
Jupiter  2  9 16 23     6 13 20  3 10 17 24     7 14 21   4 11 18   1  8 15 22    5 12 19
Mars  3 10 17 24     7 14 21   4 11 18  1  8 15 22   5 12 19  2  9 16 23    6 13 20
Sun  4 11 18  1  8 15 22   5 12 19  2  9 16 23   6 13 20  3 10 17 24    7 14 21
Venus  5 12 19  2  9 16 23   6 13 20  3 10 17 24   7 14 21  4 11 18 1  8 15 22
Mercury  6 13 20  3 10 17 24   7 14 21  4 11 18  1 8 15 22  5 12 19 2  9 16 23
Moon  7 14 21  4 11 18 1 8 15 22  5 12 19 2 9 16 23  6 13 20 3 10 17 24

The seven planets are, of course, in their traditional positions from the Earth at the center of the Solar system.

The numbers refer to the hours of the day, each of which is asigned to a specific planet. Therefore, the planet which ruled the first hour of the day, ruled the rest of that day.

Note that for traditional astrology, the actual minutes of day light and night time are divided into 12 "hours" each. These will almost never match your actual clock's dial. During much of the medieval period the day began at sunrise, or so it would seem from the sources.

Therefore

  Canonical Hours Hour Hour of the Night
6 am - 7 am Prime "Sunrise" 1 13
7 am - 8 am   2 14
8 am - 9 am Terce, Underne 3 15
9 am - 10 am   4 16
10 am - 11 am   5 17
11 am -12 pm Sexte, "Midday" 6 18
12 pm - 1 pm   7 19
1 pm - 2 pm   8 20
2 pm - 3 pm None 9 21
3 pm - 4 pm   10 22
4 pm - 5 pm   11 23
5 pm - 6 pm   12 24
6 pm - 7 pm Vespers, Evensong. "Sunset" 13 1
7 pm - 8 pm   14 2
8 pm - 9 pm   15 3
9 pm - 10 pm Compline 16 4
10 pm - 11 am   17 5
11 am - 12 am   18 6
12 am - 1 am Matins 19 7
1 am - 2 am   20 8
2 am - 3 am   21 9
3 am - 4 am Lauds 22 10
4 am - 5 am   23 11
5 am - 6 am   24 12

So since this is not yet 11 am on Friday (CST), am writing this in the first Hour of Jupiter on Venus's Day (2d hour of Saturn, GMT)

Sources:
Albertus Magnus. Secrets of Albertus Magnus.
Francis Colson. The Week.
Henry Cornelius Agrippa of Nettesheim.  Three Books of Occult Philosophy.