Planetary Hours And Days
At the first glance, Planetary Hours are similar to the ordinary hours which all of us are used to. A Planetary Day consists of 24 Planetary Hours, and an ordinary day consists of 24 hours. But here similarity ends.
Planetary Day begins at the moment of sunrise in the given place, while ordinary day begins at midnight. Since the moment of sunrise is generally different for different places, every place on the Earth has its own Planetary Day, while ordinary day is the same for all the places in the same time zone.
Ordinary hours always have the same continuity (60 minutes), while the length of Planetary Hours varies around the year, and Day Hour is usually not equal to Night Hour (these are equal to each other, as also to ordinary hour, only twice a year - at the Vernal Equinox, around 21st of March, and at the Autumnal Equinox, around 22nd of September).
How to calculate Planetary Hours
First of all, you don't need to calculate planetary hours by hand. There is a Planetary Hours Calculator that will do the calculation for almost any location and for practically any date. The explanations that follow are written for those who is curious to know the algorithm and who doesn't mind to do some math.
Planetary hours depend on the date and the location. Let the date be the 28th of June and the location - Glasgow, UK. Figures will be different for other places and dates.
On that date, sunrise in Glasgow was at 4:37 am and sunset - at 10:01 pm
The length of day time (from sunrise to sunset) is 17 hours 24 minutes, or 1044 minutes. Let's divide this number by 12. The result is 87 minutes, which is the length of one Day Hour in Glasgow on the 28th of June.
To define the length of one Night Hour we could take the period of time from the sunset to the next sunrise and divide it by 12. But it will be more efficient to use the simple rule: a Day Hour and a Night Hour summed up should always give 120 minutes. Thus the length of one Night Hour in our case is 33 minutes.
You can see that the length of a Day Hour exceeds significantly the length of a Night Hour. You can easily guess that this is typical for summer. In winter this will be vice versa. Around Equinoxes both Day and Night Hours have the length of 60 minutes.
Now that we know the length of a Day Hour and Night Hour for the given date and location, we can draw the table of the Planetary Hours shown below. As for the planetary rulers of the hours, they will be explained in a moment.
|1||Mercury||4:37am - 6:04am||1||Sun||10:01pm - 10:34pm|
|2||Moon||6:04am - 7:31am||2||Venus||10:34pm - 11:07pm|
|3||Saturn||7:31am - 8:58am||3||Mercury||11:07pm - 11:40pm|
|4||Jupiter||8:58am - 10:25am||4||Moon||11:40pm - 12:13am|
|5||Mars||10:25am - 11:52am||5||Saturn||12:13am - 12:46am|
|6||Sun||11:52am - 1:19pm||6||Jupiter||12:46am - 1:19am|
|7||Venus||1:19pm - 2:46pm||7||Mars||1:19am - 1:52am|
|8||Mercury||2:46pm - 4:13pm||8||Sun||1:52am - 2:25am|
|9||Moon||4:13pm - 5:40pm||9||Venus||2:25am - 2:58am|
|10||Saturn||5:40pm - 7:07pm||10||Mercury||2:58am - 3:31am|
|11||Jupiter||7:07pm - 8:34pm||11||Moon||3:31am - 4:04am|
|12||Mars||8:34pm - 10:01pm||12||Saturn||4:04am - 4:37am|
It is not difficult to find out which planet rules the hour. The first hour of any day is always ruled by the planet which rules that Planetary Day. The 28th of June was Wednesday, the day of Mercury, so the first Planetary Hour of that day was ruled by Mercury.
And after this, the cyclical sequence of planets is always the same: ... - Saturn - Jupiter - Mars - Sun - Venus - Mercury - Saturn - ... This sequence is named the Chaldean Sequence and it is deeply rooted in the ancient philosophy. You might notice that in this sequence the planets are ordered by their relative speed as observed from the Earth, the Moon being the fastest and Saturn - the slowest. The easiest way to remember this sequence is to have the Star of the Magi at hand: this is the sequence in which the planets follow around the star.