How Are Planetary Hours Calculated?

When I first started working with planetary hours I was a little confused as to how they are calculated. The lengths of each hour vary, and the hours didn't seem to be in any kind of order that I was familiar with. However, after a bit of research, I soon found that planetary hours are easy to calculate.

Before I explain how the hours are calculated, it is necessary that I explain the planetary rulerships for each day. These rulerships are fixed and don't change:

 Monday: Day of the Moon Tuesday: Day of Mars Wednesday: Day of Mercury Thursday: Day of Jupiter Friday: Day of Venus Saturday: Day of Saturn Sunday: Day of the Sun

In the English language, some of the planetary rulerships should be obvious in the name of the days: Saturday, Monday, Sunday. This is true of other languages, too. For example, the Spanish word for Tuesday is "Martes" (Mars.)

Now that we know Monday is the Day of the Moon, we need to know what time the day begins and ends. Is 1:00AM on Monday morning considered to be part of the Day of the Moon? No. The reason is that each planetary day doesn't begin until sunrise, and ends immediately before sunrise the next day. At 1:00AM on Monday morning it is still the Day of the Sun. The Day of the Moon will not begin until sunrise, which as you know changes not only between different locations but also on different days of the year.

Each day is then divided into two parts: day time and night time. Day time is the time between sunrise (when the planetary day begins) and sunset. Night time is the time between sunset and the next day's sunrise (when the planetary day ends, and a new one begins.) Now that we know the day time and night time, we divide these into 12 hours each, for a total of (you guessed it) 24 hours.

Still with me? It gets confusing around this part! Lets re-cap all that we've learned so far with a quick example. Say we live in London, and the date is Monday, June 21st, 2004. The sun rises in London on June 21st at 4:48AM (04:48), and sets at 9:13PM (21:13.) We know that since it is a Monday, the Day of the Moon begins at sunrise that day.

Between 4:48AM and 9:12PM is the day time, and we divide this time by 12 to get the times of the day hours: The first hour is from 4:48AM to 6:09AM, the second hour is from 6:10AM to 7:32AM, and so on. Now we do the same with the night time to get the night hours: Night time lasts from 9:13PM until 4:47AM on Tuesday. By dividing this into 12, we know that the first hour of the night lasts from 9:13PM to 9:49PM, the second hour lasts from 9:50PM to 10:27PM, and so on.

Great, now we know how to figure out the which planet rules which day, when planetary days begin and end, and how to calculate the time that each planetary hour begins. But where do the planetary hour rulerships fit in?

The planet that rules the first hour of each day is always the same as the planet that rules the day. Saturn is always the first planetary hour on the Day of Saturn, Mars is always the first planetary hour of the Day of Mars. At sunrise on Wednesday morning, it will always be the Day of Mercury and Hour of Mercury.

The planetary hours always fall in this order: Venus, Mercury, Moon, Saturn, Jupiter, Mars, Sun... and this order continues infinitely. So if the first hour of the Day of Mercury is the Hour of Mercury, the second hour of this day is the Hour of the Moon.

Lets go back to our London example for a moment. On Monday, June 21st, at 4:48AM the Day of the Moon and Hour of the Moon begin. From 6:10AM to 7:32AM is the Hour of Saturn. Is this not making sense? Just follow the order of the planetary hours: Moon, Saturn, Jupiter, Mars, Sun, Venus, Mercury, and keep repeating that until you know the planet that rules each of the 24 hours of each day.

After the planetary hours started to make sense to me, I began to use them in my day to day life. I hope that you, too, will be able to use them as a tool to improve your life!

Last Updated: 1-19-2005