The Universal Horoscope:  Astrological Influences of the Zodiac, Sun, Moon and Planets


Has anyone ever told you that your “real” zodiac sun-sign is different than you thought it was? Well, it isn’t!  Please read Tropical Zodiac vs. Sidereal Zodiac below for the reason!

The Zodiac 

     When people hear the word zodiac, many will immediately think of the signs of the zodiac:  Aries, Taurus, Gemini, etc.  But how were these signs established in the first place?  The 12 signs of the zodiac are based on constellations:  patterns and shapes that were identified in the stars and given names by ancient peoples.  To understand what the zodiac is and how certain constellations came to be included, we first need to understand some astronomy.

     Aristotle, the Greek philosopher who lived from 384 to 322 BC believed that the earth was the center of the universe, and that the sun, moon and planets all revolved around the earth.  The so-called fixed stars were thought to be part of a celestial sphere that mirrored the earth’s sphere and contained within it the entire universe.  Today we know that only the moon revolves around the earth, while the earth and the other planets actually revolve around the sun.  However, an earth-centered celestial sphere is still useful for describing the motions and positions of the sun, planets and stars; after all, we are observing them from our perspective here on earth! 

     The celestial equator is the projection of the earth’s equator out onto the imaginary celestial sphere.  The celestial equator allows us to describe the positions of the stars and planets with respect to northern and southern celestial hemispheres and north and south celestial poles.  The earth’s plane of orbit is the plane in which the earth moves as it orbits the sun.   

     If the earth’s axis was at a perfect 90 degree angle from the plane of orbit,   then the plane of orbit would be the same as the celestial equator, and the sun would appear to be directly overhead at the equator throughout the year.  But the earth’s axis is actually tilted 23.5 degrees.  From an  earth-centered observation perspective, the apparent path that the sun follows as it appears to circle around the earth is known as the ecliptic.  An equinox is when the celestial equator intersects the ecliptic:  this happens twice a year, around March 21 (the vernal equinox) and September 23 (the autumnal equinox).  The word equinox is of Latin origin, formed from aequus: equal, and nox: night.  It is at the equinoxes that day and night are the same length.  A solstice is when the celestial equator is the furthest away from the ecliptic: 23.5 degrees. This also happens twice a year, around June 21 and December 21.  It is at these times that the sun appears to be directly overhead at the two tropics of Cancer and Capricorn, respectively.  The solstices are also the times when the lengths of day and night are the most unequal.  At the summer solstice, when the sun appears directly overhead at the tropic of Cancer, the length of the day in the northern hemisphere is the longest of the year, while the length of the night is the shortest; the reverse is true in the southern hemisphere, where the day is shortest and night is longest.  At the winter solstice, the day is shortest in the northern hemisphere and longest in the southern hemisphere.

     The zodiac is a 16 degree-wide band in the celestial sphere through which the ecliptic runs.  The constellations identified within this band make up the signs of the zodiac. The signs of the zodiac are the 12 equal divisions, each 30 degrees long, which are considered to begin with the vernal equinox and progress eastward along the ecliptic.  These divisions are named for the constellations that were located in them around 2000 years ago.

Tropical Zodiac vs. Sidereal Zodiac

     Western astrology is based on what is known as the tropical zodiac.  The tropical zodiac divides the ecliptic into twelve 30 degree divisions, with 0 degrees Aries beginning at the spring equinox.  The name tropical is used because this zodiac is based on the relationship between the sun and the earth, or more specifically the position of the earth with respect to the sun at any given time of year.  The sidereal zodiac is a star-based zodiac that uses  a fixed star as a reference point.  Originally both tropical and sidereal zodiacs were in sync, but due to a phenomenon called the precession of the equinoxes, the apparent position of the sun in the ecliptic at any given time of the year is not the same as it was 2000 years ago.  This is caused by a slight wobbling of the earth as it rotates on its axis, causing a westward shifting of the equinoctial point along the ecliptic.  Since about the 3rd century the tropical and sidereal zodiacs have been moving apart at a rate of about one degree every 72 years. There is now approximately a 24 degree separation between the two, with the spring equinox, 0 degrees Aries in the tropical zodiac, falling at about 6 degrees Pisces in the sidereal zodiac.

      The differences between the tropical and sidereal zodiacs may cause some confusion. For example, if your birthday is on April 30, in tropical astrology this would be about 10 degrees Taurus.  But according to the sidereal zodiac, April 30 would be about 16 degrees Aries.  Does this mean that your “real” sun sign is Aries?  No! Your sun sign is still Taurus.  Here is the reason:  Remember that the twelve 30 degree divisions of the ecliptic are considered to begin at the spring equinox.  These divisions are based on the particular relationship of the earth to the sun at any given time of the year.  The ancient and well-established associations of certain traits, tendencies and characteristics with the signs of the zodiac are really based on the earth/sun relationship, and not on the particular constellation currently identified in that part of the ecliptic.  The signs of the zodiac provide a convenient and colorful way to divide up the sky and indicate the positions of the sun, moon and planets with respect to the earth, but the actual constellations themselves have no other significance in tropical astrology.

     With respect to the sidereal zodiac, it should also be mentioned that there are actually more than 12 constellations in the sun’s ecliptic path.  In addition to the 12 that we commonly recognize, there are also Ophiuchus the Serpent-bearer, Cetus the Whale, and Orion the Hunter.   

Astronomy in Astrology

The signs of the Zodiac, and influences of the Sun, Moon and Planets