Each Zodiac sign meshes differently with and plays to the strengths and weaknesses of each planet. There are 4 major Dignities that we’ll work through here:
Understanding each sign will give you insight into the planet that rules over it, as there’s a reason why they work so well. However, you’re cautioned against simply assuming that the signs and the planets are the same. A planet is always first in a zodiac sign, however, the vessel in which the energy is held remains the same. Mars will always rule action, just as Aries will always rule individuality. Some astrologers view the planets as energy portals, and some view them as the direct will of the deities they’re named.
Later, we’ll discuss how the astrological houses play into the dignities, but until then, let's stay focused on the balance between the planets and signs:
Traditional Dignities of the Planets
Here, we can see each dignity decided by the sign it takes hold of, and each dignity within its own sphere. This, again, is a balancing act.
Cancer and Leo are the Domiciles of the Luminaries; The Moon rules Cancer and the Sun rules Leo. Saturn, known to be the farthest planet from the Sun and Moon, is ruling over Capricorn and Aquarius which are opposite to Cancer and Leo on the zodiacal wheel. Jupiter is the second-farthest planet from the Sun and Moon, so it is placed next to Saturn within Pisces and Sagittarius.
The designation of the rulerships over each zodiac sign looks an awful lot like the true order of the planets within our solar system, with the Sun followed by Mercury and thus Venus and so on. The reason for this is that Mercury is never found more than one sign (28º to be exact) away from the Sun, so it was positioned in Virgo and Gemini to reflect this proximity. The same goes for Venus, as it is never more than 2 signs away from the Sun, and is placed accordingly. Mars is placed in the remaining two signs, Aries and Scorpio, as it finds itself in this natural placement in the Chaldean Order.
Every sign has a ruling planet, the Luminaries each have just one zodiac sign over which they find their domicile, while the traditional planets each have two. Considering the polarity which we discussed earlier, there is one diurnal and one nocturnal sign that is ruled by each planet. For example, Mercury rules over Gemini during the Day, as Gemini is a diurnal (Air) sign and is one of two signs ruled by Mercury. This is the same as Saturn ruling over Capricorn during the Night, as Capricorn is a nocturnal (Earth) sign and is one of two signs ruled by Saturn.
As each planet has two signs which it rules, one in alignment with the Sun and one with the Moon, we can split the zodiacal wheel in half over the cusps of Cancer and Leo as well as Capricorn and Aquarius and follow the same pattern (moving away from the Luminary and towards Saturn). The Luminaries differ here, as there is no reasonable sign for the Sun to rule during the Night, nor the Moon to rule during the Day.
When we dive deeper into the meaning of each planet, we will discover why each planet makes sense to rule over each zodiac sign, and why they find themselves in detriment, fall, and exaltation.
Discovering new planets through the years has left astrologers to assign dignities to each new planet, below are the modern dignities of the modern planets:
Modern dignities of the modern planets
Some zodiac signs find that they’re now ruled by two planets instead of one, those signs are Scorpio (Pluto), Aquarius (Uranus), and Pisces (Neptune). Ceres (domicile in Virgo) and Eris (exaltation in Gemini) are dwarf planets, Ceres is found in the Main Asteroid Belt between Mars and Jupiter, while Eris is a Trans-Neptunic body found at the edge of the Solar System, and is larger than Pluto!