I’ve referred a couple times now to planetary hours, or doing a working “in the day and hour” of a particular planetary power. What is a planetary hour, and how do we find them? In short, a planetary hour is a particular time that is viewed as having a special affinity for some celestial power. This post discusses a number of considerations for computing planetary hours, culminating with the system that I prefer.
Timing is an important element in ritual magic. Some grimoires, most notably the Heptameron, use different circles and names of power depending on the day, time, and season. Other workings are timed by the moon – with certain work performed during the waxing or waning moon, or while the moon is in a certain lunar mansion. In each of these cases, the time when a ritual is performed impacts its success or failure as much as the structure of the ritual itself.
This idea is influenced in large part by astrological magic – particularly from pre-Islamic Arabic traditions. Astrology is the idea that certain stars and planets exert influences over world events – the way these influences interact and aspect each other can give us a great deal of information about the character of a particular time.1 Astrological magic takes this idea a step further. By creating tools or talismans at moments when the “astrological weather” is favorable, the influences of those moments can be locked into a physical object, preserving them for future use.
Astrological magic is a rich tradition, worth exploring in its own right, but it requires – especially before the advent of computers – a high degree of technical understanding of both astronomy and math. The ability to compute star charts for particular times was by no means a common skill. Planetary days and hours evolved as a way to simplify this effort – a straightforward system to link celestial powers to certain times.
The Classical Planets
Planetary days and hours deal only with the seven classical planets – those heavenly bodies visible to the naked eye. This group includes both the sun and moon. While neither is a “planet” under the modern definition, both are celestial spheres that appear to orbit the earth.
The classical planets are placed into a standard order, arranged by the speed of their apparent motion through the signs of the zodiac. This order has its roots among the Chaldeans, so it is often referred to as Chaldean order, though it was formally set forth by Ptolemy. It begins with the Moon – the nearest and most rapidly changing body – and ascends thence through Mercury, Venus, the Sun, Mars, and Jupiter, before concluding with the slow and distant Saturn.
These planets were assigned to the days of the week by the Romans as follows:2
- Monday to the Moon
- Tuesday to Mars
- Wednesday to Mercury
- Thursday to Jupiter
- Friday to Venus
- Saturday to Saturn, and
- Sunday (naturally) to the Sun
Computing Hours
Thus far most sources agree. But there are nearly a dozen different systems for actually computing planetary hours within a particular day.
Let us start with one of the simpler systems, and one that cleaves closest to astrological magic. It comes from The Sacred Book of Abramelin the Mage: 3
Know then that each planet hath only an hour during which it is very powerful, being over your head and above your head, that is to say when it is in the meridian. Then, naturally, will sometimes arrive the hours of two planets together…
Here the hour of a planet is when it reaches its zenith above the horizon – irrespective of phase or visibility. The hour of Mars is thus when mars is highest in the sky. This is conceptually simple, but still requires us to compute the motion of celestial bodies, something that planetary hours were intended to avoid.
Instead, most systems cut up the day into some number of divisions, and assign those pieces to planets – the first hour of the day assigned to the planet of the day, and proceeding from there in descending Chaldean order, wrapping as needed.
There still remain two questions to be answered: when is the first hour in the day? And how many hours should the day be divided into?
The former is easier to answer. The first hour of the day traditionally begins at sunrise on the day of the planet in question. Thus on Monday (the day of the Moon), the first hour – also attributed to the Moon – would begin at sunrise on that day. The day of the Moon would last until sunrise on Tuesday. When in doubt, working at sunrise on the day of the desired planet is always acceptable.4
So we begin assigning planetary hours at sunrise, how long does each one last? There are three competing schools of thought here. The simplest way is to divide the whole day and night into seven equal “hours”, each approximately three hours and twenty-five minutes long.5 These hours are assigned to the planets, such that each planet has a single hour before beginning the next day. The down side of this system is that it doesn’t wrap neatly. The final hour of Sunday, for example, is attributed to Mars, the first hour of Monday to the Moon (when the natural order would be for it to wrap back around to the Sun again). This leads to strange discontinuities in the ordering of hours from one day to the next.
The next school of thought is to start at sunrise, and then divide the day and night into 24 equal hours, each 60 minutes long. The assignment of hours begins with the planet of the day (directly after sunrise), and proceeds through all planets in descending order, wrapping as needed. This has the advantage that the order of hours is continuous from day to day: the final hour of Sunday is attributed to Mercury and the first hour of Monday to the Moon, just as one would expect. The drawback of this system is messiness in the timing right around the start of the day. Since the exact timing of sunrise is rarely consistent day to day, your final hour needs to be a few minutes longer or shorter than the others, such that it ends on sunrise of the next day.6
The final method, and the one I prefer, factors in both sunrise and sunset. The number of minutes between sunrise and sunset are divided into twelve equal parts: your daytime “hours”. Then the number of minutes between sunset and the following sunrise are also divided into twelve parts as well: your nighttime “hours.” Note that the duration of the “hours” is different between the day and night; daytime hours being longer in the summer and nighttime hours longer in the winter. Planetary assignments are made exactly as in the previous case, wrapping neatly into the next day at sunrise.7 The planet of the day rules the first hour of the day (directly after sunrise), the eighth hour of the day, and the third hour of the night.
Regardless of how we choose to calculate them, utilizing planetary days and hours gives us a structured way to tie our magical efforts back to celestial powers. It gives us some of the richness of the astrological tradition without needing to consult complex tables of celestial motion. While I prefer to follow the final method – with twelve daytime hours and twelve nighttime hours – ultimately the best system for you to use is the one that integrates most naturally into your own personal practice. The way to find out what works for you is the same in this as in anything else. Experimentation.
- For example, the field of natal astrology makes inferences about the personality and proclivities of an individual by studying the arrangement of the stars and planets at the moment of their birth. ↩︎
- Our modern English names being derived by mapping the names of Germanic gods onto the Roman system, using their closest analogs: Tîwaz to Mars, Wōden to Mercury, etc. ↩︎
- Mathers, S. (1900).The Sacred Magic of Abramelin the Mage. Troy Books. ↩︎
- Some modern systems instead begin the day at midnight or at 6:00am – this latter simply being a consistent approximation of sunrise. Some traditional Kabbalistic systems use sunset. But the vast majority of traditional systems use sunrise. ↩︎
- Junius, M. (2007). Spagyrics. Healing Arts Press. ↩︎
- Alternatively, all your hours could be slightly tweaked, to maintain an equal length. ↩︎
- This final method seems to align well with the Heptameron, where the hours of the day and the hours of the night are assigned to the governance of different spirits. ↩︎
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