What is a ruling planet?
A ruling planet is the planet astrology traditionally pairs with a sign, as if the sign were its home. Mars goes with Aries, Venus with Taurus and Libra, the Moon with Cancer, and the Sun with Leo. The pairings are tradition, not calculation, and the machine's card doesn't compute them yet.
A home for each planet
Ptolemy called a sign a planet's house; later writers used domicile, from the Latin for a place to live. A planet in its own sign is said to be at home and at its strongest: Venus in Taurus or Libra, for example. 1,2
The traditional scheme is neat once you see it. The Sun and Moon take the two warmest signs, Leo and Cancer, which sit at the top of the northern summer sky. Then, working outwards from them in both directions, each planet takes one sign on either side in order of its distance: Mercury Gemini and Virgo, Venus Taurus and Libra, Mars Aries and Scorpio, Jupiter Pisces and Sagittarius, and Saturn, the slowest and coldest, the two signs opposite the lights, Capricorn and Aquarius. 1
The modern rulers
Ptolemy's seven bodies were all anyone could see. When Uranus was found in 1781, Neptune in 1846 and Pluto in 1930, modern astrologers gave them signs too: Uranus to Aquarius, Neptune to Pisces and Pluto to Scorpio. Traditional astrologers still use only the seven, so most books list both. 3,4,5
A chart ruler is a different idea from a sign ruler. It is the planet that rules the rising sign, and many astrologers treat it as the most personal planet in the chart.
The pairings
Calculated facts only, worked out the same way the machine does it.
- Tradition, not a calculation. The usual modern pairings: Aries, Mars; Taurus, Venus; Gemini, Mercury; Cancer, the Moon; Leo, the Sun; Virgo, Mercury; Libra, Venus; Scorpio, Pluto (traditionally Mars); Sagittarius, Jupiter; Capricorn, Saturn; Aquarius, Uranus (traditionally Saturn); Pisces, Neptune (traditionally Jupiter).
- The machine does compute where the planets were on your birth date. It uses the slow outer planets (Uranus, Neptune, Pluto) for your generation, and checks which planets appeared to move backwards (retrograde) on your birth date.
Where the idea comes from
Era by era, with sources. More in the Reading Room.
- Classical2nd century CEPtolemy's Tetrabiblos sets out the houses of the planets and the reasoning behind them. 1
- 1700s1781William Herschel finds Uranus; astrologers later give it Aquarius. 3
- 1800s1846Neptune is found by calculation; it later takes Pisces in modern astrology. 4
- 1930s1930Pluto is found at Lowell Observatory; modern astrologers pair it with Scorpio. 5
Common misconceptions
“The ruling planet was where that planet was when you were born.” Rulership is a fixed pairing between a planet and a sign; it doesn't change from chart to chart.
“Traditional and modern rulers contradict each other.” Most astrologers treat the modern rulers as co-rulers and keep the old ones alongside. 1
Questions people ask
What is my ruling planet?
The planet paired with your sun sign, or, for many astrologers, with your rising sign. That second one is your chart ruler.
Why do Venus and Mercury rule two signs each?
In Ptolemy's scheme the five planets each took one sign on each side of the Sun and Moon's pair. 1
Does Pluto still rule Scorpio now that it is a dwarf planet?
Astrologers who used it still do. The astronomers' label never entered the astrological tradition either way.
Sources
- Ptolemy, Tetrabiblos, Book I, chapters 10–19 (aspects, houses of the planets, triplicities), LacusCurtius, University of Chicago (Loeb Classical Library translation by F. E. Robbins, 1940). Read on .
- Domicile, Skyscript, Glossary of Astrological Terms (Deborah Houlding). Read on .
- Uranus: Facts, NASA Science. Read on .
- Neptune: Facts, NASA Science. Read on .
- Pluto Discovery Dome, Lowell Observatory, Flagstaff. Read on .