The repeating seven
The Key of Solomon gives the order Saturn → Jupiter → Mars → Sun → Venus → Mercury → Moon, and then returns to Saturn. This is often called the Chaldean order. It descends through the traditional celestial spheres rather than the modern measured distances or orbital periods of the Solar System. The Sun and Moon are included because “planet” in the source follows the seven classical wandering lights. The sequence is a feature of the historical system, not an astronomical finding of influence.
Why Sunday starts with the Sun
At the first planetary hour after Sunday sunrise, begin at the Sun’s position in the order. Continue one step for every interval: Venus at hour two, Mercury at three, Moon at four, Saturn at five, Jupiter at six, Mars at seven, and Sun again at eight. The twelfth day hour is Mercury. The first night hour, hour thirteen, follows as Jupiter. After the twenty-fourth hour, move one more step to the next sunrise: the Moon becomes Monday’s first ruler.
The same step count produces Mars at Tuesday sunrise, Mercury at Wednesday sunrise, Jupiter at Thursday sunrise, Venus at Friday sunrise, and Saturn at Saturday sunrise. This connection between the cycle of seven and twenty-four hours is why the weekday rulers appear in a different order from the underlying seven-planet sequence. Both lists are needed: the weekday fixes the starting place; the Chaldean order advances each subsequent hour.
Read a ruler table carefully
A ruler label is not enough to reconstruct an interval’s clock time. The day hours can be longer or shorter than sixty minutes, as can the night hours. A date, place, horizon convention, and the applied UTC offset are needed. Sources also vary in their treatment of midnight and dawn; when comparing tables, ask whether “day” names the civil midnight-to-midnight date or the sunrise-to-sunrise planetary cycle. This site makes its start and end instants visible alongside each ruler.