Tropical Vs. Sidereal Astrology

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Kenneth Bowser answers some frequently asked astrological questions.

What is the difference between tropical and sidereal astrology?

In the sidereal system the positions of celestial bodies are reckoned from the stars—it's a fixed stellar frame of reference. In the tropical system, the positions of celestial bodies are reckoned from the equinoxes and solstices—it's a seasonal frame of reference. The tropical zodiac is known as the "moving zodiac" because the equinox is constantly drifting westward against the background of the stars. The tropical zodiac moves with respect to the stars because it doesn't take into account one of the earth's orbital motions: precession. Precession can be illustrated by looking down at a child's spinning top. The top has a secondary motion inside its spin—it wobbles or precesses about its spin axis—just as the earth's pole describes a complete circle with a radius of 23 and 1/2 degrees in 25,800 years. This means the equinoxes continuously point at different stars over time—not the same star year after year—on the days of the equinoxes. The rate of change between the equinox and the sky is approximately 50.25 seconds of arc per year or about one degree every 71 and 2/3 years. The term "tropical" refers to the tropics of Cancer and Capricorn that describe the limits of the Sun's maximum declination values north and south of the equator. The Sun's declination is zero at the spring and autumnal equinoxes when day and night are equal. Sidereal astrology employs declination to describe positions of bodies but not to define the limits of the zodiac.

How does the actual practice of western sidereal astrology differ from tropical astrology?

The main difference is, of course, the zodiac. Both tropicalists and western siderealists use primary directions, secondary and tertiary progressions, transits, astrocartography and other methods. The are two main points of departure: timing, and the problem of tropical versus sidereal sign meanings. In the first case, because tropical reckoning ignores precession, a timing error accrues with age that becomes an entire degree by age 72. The Sun takes about a day to advance a degree in the zodiac but Saturn can take more than a month to move a full degree. For example, if a transiting planet reaches a natal planet in tropical zodiac reckoning for someone who is 58, President Bush's age, one might assume that the effects will be felt immediately. But generally, nothing happens. By tropical reckoning, transiting Saturn will conjoin Bush's natal Saturn on October 8, 2004. But forty-eight minutes and 58 seconds of precession will have accrued since Mr. Bush's birth by the fall of 2004. In terms of sidereal reckoning, transiting Saturn will conjoin his natal Saturn exact to the second of arc on election day. The sidereal astrologer would say that Mr. Bush will experience transiting Saturn conjoined to its natal place not on October 8, 2004 but on November 2, 2004, almost 25 full days later. In the second case, the problem is legitimacy. The sidereal position is that trait characteristics derive from the archetypal and original zodiac: the zodiac of the stars. An archetype is invested with meaning because it is original and self defining. It exists regardless of our awareness or beliefs. This issue addresses the matter of whether trait characteristics are carried by the sidereal signs or the tropical signs. In other words, which one is invested with legitimacy? They can't both be right. As the tropical signs precess farther and farther away from their sidereal namesakes, the most glaring issue between tropical and sidereal reckoning is thrown into bold relief. The meanings of the tropical signs have evolved to compensate for the problems of precession as the signs have slowly moved out of the territory of the constellations that was their original venue. For example, most of what is called Scorpio in terms of tropical zodiac reckoning is the constellation of Libra. Scorpio is aggressive, insistent, penetrating and intense. It is typically harsh, forceful, intolerant of opposition and will attempt to crush an opponent by any means. Libra is ruled by Venus. It has a tender, artistic, pleasure loving and gentle quality. Libra is clearly a lover—and not a fighter—like Scorpio. The result is that tropical Scorpio is assigned many of Libra’s qualities. It is seen as sensual and erotic. This sort of bleed-over has happened with all the signs. Sidereal astrology restores the crispness of the sign traits to their original venue which was usurped by the adoption of the tropical zodiac in the West. The sidereal position is that if someone has the Sun in tropical Scorpio but sidereal Libra, only the Libran traits are considered valid.