Exploration of Heliocentric and the Solar Dimension
by T. Patrick Davis (1927-2001) Heliocentric pioneer

Re-published from the Astrological Journal September/October 1991. (This article has been edited due to length and outdated information)

When I began probing the solar dimension so long ago, I had no clue on whether Mercury in the heliocentric system had an astrological influence, and if so, if it was the same as that associated with it in traditional geocentric astrology or distinctly different. All of the planets were a mysterious unknown quantity in this other dimension. No enlightening references were found. Given the nearly universal absence of comment and astrological use of the heliocentric system, prospects appeared bleak that there would be much of anything interesting to astrologers.

What piqued my Aquarian curiosity originally were some studies rising out of the Space Age, not associated with astrology. There were intriguing findings that the use of heliocentric coordinates for planetary patterns were linked with actual physical effects on our own planet. This indicated a measure of astrological significance! At the time, no daily ephemeris designed for astrologers was available and so my curiosity could not be satisfied until a Digi comp DR-70 computer became available which provided heliocentric positions. My quest was on. From that time to the present it has been one surprise after another. It has been mentally exhilarating. It has also been a can of worms! My approach was to experiment open-mindedly hoping the solar system would tell me how it worked through studying real people's charts and their experiences. Very early in the study some quite unexpected and thoroughly perplexing observations served as warning on the dangers of jumping to conclusions rising out of assumptions based on preconceptions! "Assume nothing when exploring unknown territory" became my watchword in 1979 when the study became a full-time occupation. The first thing to exhume from the mind is that heliocentric astrology is just another technique. It is another dimension. That much is clear, but we are only open the threshold of a full understanding of its role and influence. Heliocentric is not an insignificant element symbolized as a small number to the far right of a decimal. It is a major number to the left of the decimal.

What is Heliocentric?

The word 'helio' is another name for the Sun, so 'heliocentric' means Sun-centred. We are talking of the solar system, with the Sun in the centre and the planets, including Earth, circling around the Sun. When we speak of heliocentric coordinates of the planets, it is their positions in this relationship, they can be quite different from those calculated where the Earth is taken as the centre. The word 'geo' is another name for planet Earth, so the geocentric system of traditional astrology uses Earth as the centre of focus, calculating the positions of the planets as they appear to be circling us. Those who cannot conceive of influences reaching us from the heliocentric system, who repeat the old confusing phrase, "I don't live on the Sun" are reminded that planet Earth moves through the solar wind.

There are no hypothetical planets to deal with when working with the heliocentric system. We have the same familiar planets shifted in position over to their true positions as they circle our central star, the Sun. There is no retrograde motion to consider with heliocentric. Abbreviations to 'geo' and 'helio' will be used freely here as a method of conserving trees being cut to create paper. A 'geo Mercury' will indicate its traditional position in the geocentric system. A 'helio Mercury' will indicate its position in the solar system.

Differences in position

Each planet has its own orbit and distance from the Sun or Earth, so each one will have its own rules. With Mercury and Venus being closer to the Sun than Earth, and moving around the Sun much faster, these two planets can have the widest variations between their geo and helio positions.

Mercury circles the Sun every 88 days, so the widest variations in the shortest time are registered between its geo and helio position. In secondary progressions. Mercury can move around the entire chart in 88 years, now well within the lifetime of many people. Mercury moves fastest through its own sign of Gemini and slowest through its opposite sign of Sagittarius, in the same way Pluto moves fastest through its own sign of Scorpio.

As the distance increases between a planet and the Sun, the differences between their geo and helio positions decrease. The common ground between the two systems is the zodiac of the signs. Michael Erlewine published this list to show the maximum elongation between the two sets of coordinates:

VENUS 180°
EARTH Always opposite Sun.
MARS 47°23'
JUPITER 11°51'
SATURN 6°29'
URANUS 3°11'
PLUTO "About the same as Neptune."

When looking at a traditional geo chart, and seeing Mercury or Venus direct-in-motion and tightly conjunct the Sun, they are circling on the far side of the Sun from us here on Earth. However, if they are retrograde and conjunct the Sun, Mercury or Venus are orbiting between the Sun and Earth, and come closest to Earth at this time. If you draw their heliocentric positions into the chart, they will be shown opposite the Sun and conjunct Earth, or in the sign opposite the Sun and the geo position.

When any of the outer planets. Mars through Pluto, are either exactly conjunct or exactly opposite the Sun, the heliocentric position will be shown alongside the geocentric position.

During a very brief period when Mercury appears to be making its direct or retrograde station in the geo system, the helio position of Mercury will be trine the geo position. Mercury-trine-Mercury? People such as Leonardo da Vinci and Benjamin Franklin were born with Mercury-trine-Mercury, as were inventor-innovators Lawrence Hargrave, George Eastman, Lee de Forest, and Jean Foucault, for example. It is a thought provoking observation.

Heliocentric Planetary Influence

After much experimentation with multiple thousands of charts, there was a recognition that the core influence associated with a planet bore the same characteristics between the systems. However, the heliocentric planets are functioning on a different wave length, so they are not completely interchangeable between the two systems. Maintaining identification of the system is necessary.

Each planet in each system has its own implications, yet within the framework traditionally associated with its influence. For example, both geo and helio Venus are linked with sociability, things valued, and a sense of success, but helio Venus seeks wider recognition than will satisfy geo Venus urges. The romantic implications of geo Venus may lead to a wedding, but the helio Venus becomes prominent if the wedding is a grand ceremony with a large guest list. Helio Venus is not intimately personal like geo Venus, unless one considers it in the light of what the successes and status it seeks does for the ego. And here we return to the significance of the Sun - helio.

The planetary influence from the heliocentric system draws us out to interact with the larger world, to those outside our more intimate circle of family, friends, and co-workers. It represents our status in the community or internationally; it is our public life and career; it is recognition or rejection by the wider world. The geocentric system is more significant of our private lives, although there are some exceptions to be considered when one gets into details.

As an overall concept, one can relate the heliocentric influence to the career and reputation Midheaven of the horoscope, and allocate the geocentric influence to the Ascendant and interests it represents. The divine discontent urging one to seek 'a place in the Sun' varies between individuals, and yet everyone does respond.

Heliocentric Sign Influence

Sign influence is as potent in heliocentric as in geocentric. The same rulership or association of a planet with a particular sign and house is maintained in both systems. The difference is that with heliocentric involvement those matters associated with public or larger world interests rise to the surface, and thereby allow the astrologer to distinguish which is being activated. The need felt to reach out to the world beyond one's well-known associates, in either a minimal or maximum fashion, is indicated by the heliocentric.

When a helio planet progresses into a new sign, the change of interests or experiences can be dramatic for those especially sensitive to this system.

Houses and Heliocentric

Theorists assumed there could be no house influence for helio planets, but apparently never tested their preconceptions. As a result, when I inadvertently began to notice a responsiveness to house placement, it was quite disconcerting. Enormous quantities of time have been spent examining this unexpected development. As of now, no chart has been found where helio planets struck a dumb chord regarding a sensitivity to house placement. This sensitivity to houses of helio planets extends to the Midheaven and Ascendant, the angles, as well as between the progressed angles and helio planets.

Mixing Geo-Helio

The constant interweaving between our public and private lives, as well as in our concepts of recognition or simple involvement with the larger world, defies a neat separation. After working with a dual system chart for years, which originally came about as a solution to enhance a comparison of the systems, and without any idea of the revelations which would ensue, using a combined chart seems to be the only practical method.


A number of aspects between planets are possible only in the heliocentric system, such as Mercury-square-Sun (and Earth), or Mercury-trine-Venus. These 'new' aspects concentrate around Mercury, Venus, and the Sun (or Earth), because the heliocentric system releases Mercury and Venus from the bond to the Sun found in the traditional chart to show their circle around the zodiac and Sun (using an orb of approximately three degrees). It was through my early study of aspects that I began to grasp the enormous significance of heliocentric to every phase of astrology.

Including Earth

The decision to include or exclude Earth's position in a dual system chart is a matter of personal preference. The Earth is always exactly opposite the Sun [in the helio system]. Any aspect to the Sun automatically forms an aspect to Earth. After observing that people responded more as though they were receiving an opposition to the Sun rather than a conjunction with Earth, I decided to simplify the chart, leave Earth out, and keep the primary focus on the Sun. The human quest 'to find our place in the Sun' was the determining factor.

The Moon

As a satellite of planet Earth, logic would declare the Moon nearly invulnerable to heliocentric influence, yet I have not found this to be the case. Exceptionally dramatic examples come to mind, most especially Moon-helio Venus or Mars mixes which were classic. Experiments are urged not to dismiss Moon-helio planet aspects without examination.

The Dual System Chart

Neatness counts when both systems are drawn into the chart circle. It is necessary to really look at the chart, but the rules for finding particular planets are actually quite simple. Locate the Sun first. The geo Mercury or Venus will be close to the Sun. If either are retrograde, look to the other side of the chart for its helio position. With any of the planets, the geocentric position will be closer to the Sun than its counterpart in the heliocentric system. For fast-moving Mercury, its helio position is likely to be considerably farther ahead or behind its geo position.


As these fundamentals have been given, it should be clear that there are some highly significant differences between the systems, [for example] Mercury is Mercury in either system. A square aspect retains its challenging influence. Rulerships are familiar, and so on. The enormous advancement in understanding our role in this universal ecological system and in timing changes makes the effort more than worthwhile.

T. Patrick Davis started her astrological teaching career early in 1960 in St. Louis, MO, continuing it after moving to Peoria, IL . She participated in Recent Advances in Natal Astrology [published by the AA]. T. Pat was Founder and past President of the Illinois Federation of Astrologers and is a past Board Member of both the Academy of Science and the Astronomy Society. She joined the Faculty of AFA in 1972, and shortly thereafter published her first book. Her titles include New Methods of Rectification: Lincoln, Interpreting Geo-Helio Planets, and Revolutionising Astrology with Heliocentric. From 1979 all her efforts became concentrated on grasping the implications of the heliocentric system in practical, down-to-earth astrology.