In the horoscope, each planet represents an acting force, either internally in a person or externally in the world. The planets are the only active components in the horoscope. The Zodiac signs, the Houses and the aspects, give character and settings to them, or links them together - but what generate action, activity, are the planets. The planets express what happens, the Houses where it happens, the aspects why, and the Zodiac signs how.
     Not all of those objects that group as planets in astrology, are actual planets in an astronomical mea­ning. The sun and moon are included. Also included are the Ascendant and the Medium Coeli, although they are no celestial bodies at all.
     The Ascendant (AC) is the rising point of the Zodiac on the eastern horizon, which is why it is also called Rising, and Medium Coeli (MC) is the highest point of the Zodiac, therefore also called Midheaven. They have their counterparts in the Descendant (DC) and the Imum Coeli (IC) - at exact opposite sides of the Zodiac. There are also the moon nodes, called the Dragon's Head and the Dragon's Tail, exactly opposite one another in the horoscope.
     Since the above components are all dealt with similarly in astrology and the horoscope, I allow myself to group them as planets.
     Some astrologers include additional points and celestial bodies. Anyway, the twelve most important planets and the characters of their forces are:

    Sun   basic drive
    Moon   longing
    Mercury   curiosity
    Venus   affection
    Mars   aggression
    Jupiter   luck
    Saturn   duty
    Uranus   contemplation
    Neptune   fantasy
    Pluto   catharsis
    Ascendant, AC   attitude
    Medium Coeli, MC   self-image



Velocity
Some of the planets move as fast as one full rotation around the Zodiac in a day, and the slowest one needs almost 250 years to do the same. This is important to consider in the interpretation of a horoscope. The positions of the slower planets are shared almost by a whole generation of people, which is why they are called generation planets. The quicker ones can be said to be more personal, since they move significantly in a matter of days, in some cases hours.
     Here are the times it takes for them to make one rotation around the Zodiac, in round numbers - from a geocentric perspective, ie. as seen from the earth.

    Sun   1 year
    Moon   1 month
    Mercury   1 year
    Venus   1 year
    Mars   2 years
    Jupiter   12 years
    Saturn   29 years
    Uranus   84 years
    Neptune   164 years
    Pluto   248 years
    Ascendant, AC   1 day
    Medium Coeli, MC   1 day

     When interpreting a generation planet in the horo­scope, it is more important what House it is in, than what Zodiac sign, since the latter is shared by all peo­ple born around that time.

Retrograde
Because the perspecitve in astrology is geocentric - seen from earth - planets do at times seem to move backwards in the sky. This movement is called retrograde, and is the result of earth's own movement. In the horoscope, planets that are in retrograde are marked out as such, since this is taken into consideration in the interpretation of the horoscope.
     Generally speaking, retrograde planets are weakened and their force becomes more subtle and complex.

Astrological characters
In reality more than in astrology, the sun and moon stand out from the other planets. In the horoscope, all planets are significant and active in their separate ways - not at all shaded by sun and moon, the way they are in the sky to the naked eye.
     How the planets were given their respective astro­logical characters (as listed above) is buried in the past. Any astrologer would like to regard it as a development of trial and error - that experience taught astrology the meanings of the planets.
     Seven of the planets are visible to the naked eye - the sun, the moon, Mercury, Venus, Mars, Jupiter and Saturn. The outer planets were only discovered after the invention of the telescope, and quite late at that - Uranus in the 18th century, Neptune in the 19th and Pluto in the 20th. The meanings of these planets in the horoscope have largely been deducted from the times of their discoveries.


The heavenly spheres. Illustration from a 16th century book by Bovillus.

Rulers
Planets are traditionally said to rule over Zodiac signs, in which they are enforced by the character the sign gives them. A planet rules over the Zodiac sign where it fits better than other planets do. It should not be stressed too much in horoscope interpretation, since that enforcement is evident in itself, when the planet's kind of force and the Zodiac sign's character are combined.
     Only true celestial bodies can be rulers of Zodiac signs. Since there are just ten of them, and the Zodiac contains twelve signs, two planets rule two signs each. Astrologers agree on most, but not all, of the rulers. Here are the planets and the signs where I would say they rule:

    Sun   Leo
    Moon   Cancer
    Mercury   Gemini and Virgo
    Venus   Taurus and Libra
    Mars   Aries
    Jupiter   Sagittarius
    Saturn   Capricorn
    Uranus   Aquarius
    Neptune   Pisces
    Pluto   Scorpio

Exalting
The planets are also said to exalt in Zodiac signs - that is where they are enforced, but not to the extent they are in the signs they rule. Again, this should not be emphasized in horoscope reading, and again astro­logers are of slightly differing opinions. Here are the signs in which I would say the planets exalt:

    Sun   Aries
    Moon   Taurus
    Mercury   Libra and Pisces
    Venus   Cancer and Virgo
    Mars   Capricorn
    Jupiter   Gemini
    Saturn   Aquarius
    Uranus   Sagittarius
    Neptune   Scorpio
    Pluto   Leo

Symbols
The symbols used for the planets are the same in astrology and astronomy. I have made ink brush ver­sions of those symbols, just for fun. Here is a more strict rendering of them:


Planet symbols. From left to right: sun, moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, Ascendant, Medium Coeli, moon node.


© Stefan Stenudd, February 19, 2006
Horoscope Basics
Zodiac
Planets
Houses
Aspects