Re: Guidelines for Practical Use of Synodic Cycles
Good questions Javed. Synodic Astrology really deserves an entire book. I'll do my best to give some insights.
Re: your first question: "...will a synodic cycle (of other planets, centaurs etc.) have significant meaning only if say the synodic conjunction and the subsequent square, opposition etc. fall on important significators in one’s chart? "
I would not say "only," but yes, like a New Moon, eclipse, or other lunar phase changes have extra significance if they conjoin natal planets or personal points, so too will synodic cycles. In addition, much like you might look at where in a natal chart a new lunar cycle, eclipse, etc. begins, so too is the chart location in which the synod occurs of significance, whether conjoining a natal planet or not. For example, consider how a new lunar cycle would express differently for you depending on which house it occurs in your natal chart--how a lunar cycle gets personalized. The same certainly holds true for new synodic cycles (and their phase changes).
So the obvious next question is: "...should we be looking at aspects to heliocentric natal planets? "
Keep in mind our solar system is one evolutionary system--heliocentric and geocentric are not separate, just relative; and astrology works through harmonic resonances in geometry. Let's say for example your natal (geocentric) Sun (or any other planet) is at 15° Scorpio, and there is a new Jupiter-Mars synod (which is only viewable from the Sun's perspective (heliocentric), also occurring at 15° Scorpio. You essentially have a significant point of resonance at this ecliptical longitude to start with, and those star alignments at that ecliptical longitude are principle for you--that is an absolute. So the heliocentric synod occurring at this ecliptical location is of extreme significance. You can consider it as a cross-resonance occurring directly between the heliocentric synod and your natal geocentric Sun. Keep in mind in a situation like this that your Sun stars and the synod stars are the same; thus the theme of the new synodic cycle is one and the same as your solar theme. And the synodic cycle will unfold as if conjunct your Sun--and effecting that area of your life in which your Sun resides. I think this heliocentric synod to geocentric natal resonance is quite significant and quite intriguing to explore. It provides a deeper understanding into the nature of the underlying forces and cycles at work in our personal evolution and driving our life experiences. So here we tie together your first two questions: If a new (heliocentric) synodic cycle starts at the ecliptical location of your DSC or in your 7th house, for example, you can be sure that new synodic cycle is going to unfold in that area of your life; i.e., in your personal and significant relations, how you interact in the world, etc.--DSC themes.
Another area I find quite revealing and certainly intriguing when exploring natal synodic astrology is to look at where natal planets reside in their synodic cycles--looking at both Earth-planet synods and planet-planet synods. This is similar to looking at the New Moon lunar cycle theme immediately before birth and when in that lunar cycle you were born, which is of extreme significance and quite revelatory. A nativity is a snapshot in spacetime of many unfolding and interweaving cycles--a timeline we jump into and participate within as our lives unfold. If I were born immediately following a first quarter moon (Sun 90° square Moon), my life theme (in part), emotional motivation, would be about initiating action, But action in what context? To find out, I would look at the pre-birth New Moon lunar cycle theme. Similarly, if I were born just after last quarter moon (Sun 270° square Moon), my life (in part) would be about initiating change, discarding the past stage setting, facades, etc., associated with the lunar cycle's theme. Synodic cycles are the same, we punctuate into a durative ever-changing harmonic symphony of cycles when we birth and we can look at the synodic cycle themes in which we were born and when in those cycles we were born; i.e., into which phases and their phase characteristics.
Say for example that I have retrograde Jupiter in near opposition to my natal Sun in my natal chart. This means a new Earth-Jupiter synod is about to occur or has just begun. If I were born just before the synod, this would mean I am at the point of surrender and abandonment of the entire previous synodic cycle, a need to surrender to allow a new cycle to emerge. If I were born just after the synod, a new synodic cycle theme would have just started with the new theme emerging. This alone brings great insight into the nature of my Jupiter-related experience. In the first case, I would be quite interested in the previous Earth-Jupiter theme as well as the one about to begin. Exploring the previous cycle would bring insight into that which I am moving from, done with, letting go of; and exploring the new cycle would reveal that which I am moving toward, what I need to be open to embrace to begin a new expression. Looking at this greater context can provide tremendous insight into the nature of not only my Jupiter experience but also that of my Sun and the opposition. Similarly if I were born at another point in the Earth-Jupiter synodic cycle, I would explore the nature of the original pre-birth synodic theme, as well as the phase characteristics, just like those of a lunar cycle. Knowing whether I am in the inspirational first quarter, creatively formulating ideas; in the second action and involvement quarter, in the manifestation quarter, etc. can be very helpful to gain a deeper understanding of my self, how I tick, and of my life experience.
Consider also all of the other planetary relationships in the natal chart as well, not just aspects, but where the planets are in the respective synodic cycles. The more you explore this the more you will come to see the transparency or cross-resonance between the heliocentric and the geocentric. Say you have retrograde Saturn 90° square from Pluto. Most likely you are very near the first heliocentric synodic square. If you are just before the 90° square, you are in the stimulus to action phase characteristic (common to fears surfacing or hesitation to take action). If you are just after the synodic cycle's square you are in the action mode--and again, in the context of the original Saturn-Pluto synodic theme.
You may also find that the ecliptical location of a pre-birth synod is the same as the location of another natal planet, which can also be quite revealing. Exploring natal synodic astrology alone can open an entire new level of self awareness. It adds tremendous depth to the natal chart; it reveals our timeline rather than just a static self. It makes it clear that we have jumped into a wild moving river of life in which we must navigate; and to know from where the currents have come and where they are going can be of great help to gain our bearings and to learn what we are really doing here.
Regarding posting synodic cycle phase changes: You can see the new and full (mid-point) of cycles on the Synodic Cycle Timeline accessible on the Synodic Cycles and Planetary Retrogrades
web page. I will consider adding additional phase changes when time permits.
Notice that whenever you see one planet in its retrograde squaring another planet in a geocentric chart, a heliocentric square is near, which you can see in a heliocentric chart. For example, as presented in the Makemake-Uranus-Saturn 2008-2011
article, the Saturn-Pluto geocentric square runs from November 15, 2009 through August 21, 2010; and the heliocentric 270° square occurs in the midst of this on June 11, 2010. This is the second square in the 37-year Saturn-Pluto synodic cycle that began on December 24, 1982. Thus the Saturn-Pluto synodic theme defined then is of significance when examining the nature of this several month geocentric square, which catalyzes an "inner need to change" regarding this synodic cycle's theme. Similarly, the Jupiter-Pluto geocentric square runs from Jupiter's station in July 2010 through February 25, 2011; and the heliocentric 90° square occurs in the midst of this on December 10, 2010. This is the first square creating an "external stimulus to action" in the 13-year Jupiter-Pluto cycle that began on November 23, 2007. Thus again, the nature of this synodic theme brings insight into the nature of the stimulus to action.
Just a few thoughts. Hope that helps.
Think stars not mere signs. Think cycles not just aspects.