What planetary hours are
Long before clocks, the day was counted from sunrise to sunset in twelve hours and the night from sunset to sunrise in twelve more. Astrologers gave each of those hours to one of the seven planets they could see: Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon. The planet that owns an hour is its ruler, or lord, and the hour is said to share its nature. A Venus hour is a Venus kind of time and a Saturn hour a Saturn kind of time, in the same way that the planets lend their character to the signs and houses they rule.
The scheme is very old. It was known in the Roman world, Arabic and Persian astrologers handed it on, and al-Biruni sets it out in his Book of Instruction, written in Ghazna in 1029. It also explains the order of the weekdays and the names they carry. The card at the top of this page applies it to today: it finds sunrise and sunset for your city, divides the day and the night into hours, and shows the planet ruling now and the one that comes next. The table below it lists all twenty-four, and you can pick another date.
The Chaldean order
The planets follow one another through the hours in the Chaldean order, which ranks them by how slowly they seem to move against the stars, from the slowest to the fastest: Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon. In the old picture of the cosmos it was also the order of their spheres, from the outermost inwards.
The first hour after sunrise belongs to the ruler of the weekday, and from there the hours run down the order and start again at the top. A day and a night make twenty-four hours, three more than three full rounds of seven, so the first hour of the next day falls three places further down the list. That is where the order of the week comes from. Sunday begins with the Sun; three places on is the Moon, ruler of Monday; three more is Mars, ruler of Tuesday; then come Mercury, Jupiter, Venus and Saturn. The English names keep the pattern openly in Sunday, Monday and Saturday, and the other four through the Germanic gods who were matched with Mars, Mercury, Jupiter and Venus. The Romance languages keep the Latin planets: martes, mercredi, giovedì, viernes.
The night has its own first hour. On Sunday the thirteenth hour, the first after sunset, falls to Jupiter. Al-Biruni gives the shortcut: the lord of the night is the third planet upwards from the lord of the day, counting the day’s lord as the first.
Unequal hours
The hours on this page are unequal hours, also called seasonal or temporal hours. Each day hour is a twelfth of the time between sunrise and sunset, and each night hour a twelfth of the time between sunset and the next sunrise. They stretch and shrink with the seasons: in London at midsummer a day hour lasts well over sixty minutes and a night hour well under, and at midwinter it is the other way round. Near the equator they hardly change at all.
That is why the planetary hours do not begin on the hour by your watch, and why two cities in one time zone have different hours. Sunrise and sunset here are the moments when the upper edge of the Sun touches the horizon, allowing for the bending of light by the air, as in the standard method set out in Jean Meeus’s Astronomical Algorithms; the page works them out for the city you choose, at sea level. Close to the poles, on a day when the Sun does not rise or does not set, there is no sunrise to begin from, and the page says so instead of inventing hours.
The unequal hours were not the only way. Al-Biruni noted that the Hindu astronomers of his time gave a whole day and night to one planet and counted equal hours, which he found the more natural method. The astrologers of his own tradition kept the unequal hours, engraved them on their astrolabes, and passed them on to European astrology.
Choosing an hour by tradition
The practical use of the hours is to choose a time. Each planet signifies certain things, and the tradition suggests beginning a matter in the hour of the planet that signifies it:
- Sun: dealings with people in authority, recognition, matters of honour.
- Moon: journeys, the home, the public, anything meant to move and change.
- Mars: courage, competition, physical effort, cutting through an obstacle.
- Mercury: writing, study, messages, contracts, buying and selling.
- Jupiter: law, money, favours, growth, asking for help.
- Venus: love, friendship, pleasure, art, making peace.
- Saturn: land and buildings, long-term work, patience, endings, what needs to last.
Many people use the list lightly: they send the important email in a Mercury hour or arrange a date in a Venus hour, a small habit that fits the action to its time. The tradition itself treats the hour as a modest help. A fitting hour does not turn a poor plan into a good one, and electional astrologers who choose a moment with care look at the whole chart of that moment, the Moon and the Ascendant above all, and use the hour as a finishing touch.
Planetary hours in horary
In horary astrology the hour has a narrower job. Among his considerations before judgement, the checks an astrologer makes before reading a question, William Lilly calls a horary chart radical, fit to be judged, when the lord of the hour at the time of the question and the lord of the Ascendant are the same planet, or of the same triplicity, or of the same nature. The idea is that the moment and the person asking should agree; when they do, the chart describes the question truly.
Modern horary astrologers differ on how much weight to give this test, and many treat it as a curiosity next to Lilly’s other checks. Either way the hour is a check on the chart, not the answer. The answer comes from the significators: the planets ruling the querent and the matter, the aspects they are making and the Moon’s next move. The horary astrology guide explains them, and the void of course Moon page shows the state of the Moon’s course right now.
Where AstroGPT fits in
The hour describes the time; it says nothing about your particular matter. Whether a job offer comes, whether a message gets a reply, whether a deal goes through: each of these is a question, and horary astrology answers questions with a chart of the moment they are asked. That is the work AstroGPT does. You type the question, and it casts a chart for that minute at your location and reads it, in Western mode with Equal houses and the traditional significators, in Vedic mode as a Prashna. Its reply starts with a verdict and shows the testimony behind it; for the next hour, more questions can go to that same chart.
The planetary hour is not part of an AstroGPT reading. The chart decides the answer, and the hour stays yours, to use as the tradition suggests or to ignore. To see the sky of this minute for yourself, open today’s planetary positions; for the chart of your birth, try the birth chart calculator. Everything here is offered for reflection and entertainment.
The hour sets the tone; a chart answers the question
For a particular question, AstroGPT casts a horary chart for the minute you ask, where you are, and reads the answer from its significators. Start with free trial questions.