Planetary Hours

The planetary hours are not actually one hour long. They will change depending on the date. This is because the daytime hours and nighttime hours are separate groups. So please keep in mind that, outside of calculations, "hour" does not actually mean 60 minutes.

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WARNING: MATH

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To calculate the daytime hours, you want to find out how many minutes are between sunrise and sunset. Then divide that into twelve. For example, today, where I am (because your location will change the times), sunrise is at 6:51 AM. Sunset will be at 20:47  (8:47 PM). That's 13 hours and 56 minutes, which is 836 minutes. (13 x 60 + 56 = 836. Remember PEMDAS? And we thought we'd never use it!) Divide that into 12 to get 69.6, so each daytime planetary hour will be 69 minutes and 40 seconds. (Personally, I don't sweat the seconds, but it is technically the best way to do it since it'll throw your minutes off a tiny bit if you don't take them into account.)

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To make that into simple formulas, for anyone who might want them, it's:

sunset time - sunrise time = X hours and Y minutes

X x 60 + Y = minutes

minutes / 12 = planetary hour duration

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(Remember to use military time format to make this work more easily.)

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Now! To figure out the planets for those hours, you will first need to memorize which planets rule which days. Done? Cool.

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So the first hour of sunrise will always be ruled by that weekday's ruling planet. If it's Sunday, the first hour is the Sun. Always. Monday is the Moon, Tuesday is Mars, etc. Got it? Good.

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Now, to get the second hour, go back two days and use that day's ruling planet. To get the third hour, go back two more days. The fourth hour, two more days. Just keep doing that.

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Example:
Today is Saturday, so the first planetary hour is ruled by Saturn. The second hour will be the planet that rules two days before Saturn. Saturday, Friday, Thursday, so it'll be Jupiter. Two days before Thursday is Tuesday, so the third hour is Mars.

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The nighttime hours... are done exactly the same way. The only difference is that you'll calculate the minutes between sunset and sunrise of the next day. Everything else is exactly the same.

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To get the minutes between sunset and sunrise is a bit trickier, since we can't do simple subtraction like the other. The easiest way to do it is probably like this, using military hours:

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(sunrise + 24 hours) - sunset = minutes

So let's say sunset tonight is 20:47 and sunrise is at 6:50 tomorrow. If we add 24 hours, now we have 30:50 for sunrise.

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30:50 - 20:47 = 10 hours and 3 minutes.

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Everything else will be the same as the daytime formulas.

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Or you could use the planetary hour calculator below to do all that pesky math for you! I just wanted to give an explanation so that you can figure it out on your own if you ever want or need to.