← Encyclopedia of Astrology · lesson 211/235
Planetary hours
What it is
Planetary hours are astrology's everyday clock. The time from sunrise to sunset is divided into twelve "hours of the day", and the time from sunset to the next sunrise into twelve "hours of the night". Each of the twenty-four is ruled by one of the seven classical planets — Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon — taken in a fixed rotation. The planet ruling the first hour after sunrise also rules the whole day.
Unequal hours
These are not clock hours. Because daylight is longer in summer and shorter in winter, a daytime planetary hour in June is well over sixty minutes in northern latitudes and a night hour correspondingly shorter; in December it is the other way round. Only near the equinoxes are they close to sixty minutes each. Lilly notes that some of the ancients used equal hours, but that astrologers follow the motion of the Sun summer and winter — these are sometimes called temporal or unequal hours. The planetary day therefore begins at local sunrise, not at midnight, and the hours change with where you stand: two towns on the same day have different hours.
The Chaldean order
The planets follow the Chaldean order, from slowest to fastest as they appear from Earth:
Saturn → Jupiter → Mars → Sun → Venus → Mercury → Moon → (Saturn again)
The first hour of the day belongs to the day's ruler, and the sequence then runs round the seven planets through all twenty-four hours. Because 24 leaves a remainder of 3 when divided by 7, the first hour of the next day falls three steps further along the order — and that is how the rulers of the days come out:
- Sunday — Sun
- Monday — Moon
- Tuesday — Mars (French mardi)
- Wednesday — Mercury (mercredi)
- Thursday — Jupiter (jeudi, from Jove)
- Friday — Venus (vendredi)
- Saturday — Saturn
The English names keep the Sun, Moon and Saturn and swap in Germanic gods for the rest; the French and Italian names keep the planets almost intact. The week itself is a fossil of this scheme.
How it is used
Planetary hours belong mostly to electional astrology — choosing a moment to begin something — and to horary astrology.
- Choosing a moment. The tradition matches the hour to the business: a Venus hour for love, art and reconciliation; a Mercury hour for writing, contracts and messages; a Jupiter hour for growth and generous requests; a Mars hour for bold or cutting work; a Saturn hour for discipline, endings and patient, structural tasks; the Sun's hour for authority and visibility; the Moon's for home, the everyday and the public. On its own an hour is a light testimony; serious elections weigh it beside the condition of the Moon and the angles.
- Horary. Lilly treats the lord of the hour as one of the considerations before judgement: a question is judged with more confidence when the lord of the hour agrees with the lord of the Ascendant by being the same planet, of the same triplicity, or of the same nature.
Read as tradition intends, an hour is a gentle nudge about timing, not an instruction.
In a reading here
The Almanac, on the web and in the app, computes the planetary hours for the place it is set to — local sunrise and sunset, in the Chaldean order, with the day's ruler, the hour you are in, and a table of all twenty-four hours, day and night. Electional readings use the actual planetary hours when refining the moments they suggest, and favour an hour whose planet fits the activity; horary readings check whether the lord of the hour agrees with the lord of the Ascendant.