Synodic Astrology
Synodic Cycles and Planetary Retrogrades

Cycles of Growth in Consciousness

Introduction to Synodic Cycles & Synodic Astrology

Planetary Synodic Cycles are cycles that occur between one planet and another. There are many cycles occurring at the same time, all interweaving and nesting in one another. Synodic Astrology explores these planetary cycles, the themes of the cycles, and where we are in the progression of the cycles.

A natal astrology chart (or any astrological chart) is a picture of one moment frozen in time. Looking at the aspects of the chart in the context of the cycles in which they exist is like looking at the movie from which that picture was taken. In doing so we gain far greater understanding of the meaning of the picture and how it fits into a greater evolutionary narrative. Looking at the location of the planets at the start of a cycle, the theme of the cycle defined by the conjoining stars, and where we are in each cycle provides far more insight about the snapshot in time. This embracing context offers a far greater understanding about our opportunity for growth in life and the nature of our life experience.

Planetary Synodic Cycles start when two planets align in their orbits, looking from the Sun (although we can look at cycles relative to other planets as well, and even relative to a location on Earth). "Synod" means place of meeting. Although synods occur with all planets, when we say a Venus synodic cycle or a Mars synodic cycle, we are referring to those cycles that occur with the Earth and the planet. If we are referring to a synodic cycle created by two planets other than Earth, we then clarify that by saying a Mars-Jupiter synodic cycle or a Venus-Jupiter synodic cycle, etc.

The following illustration shows two successive synods between Earth and Venus, which creates one Earth-Venus synodic cycle, and which has a duration of 1.6 Earth years.

Earth-Venus orbits and their 1.6-year synodic cycle

See the Venus web page for more about Earth-Venus synods and their precessional pentagonal pattern.

The Earth-planet star alignments (looking from the Sun / heliocentric view) reveal the nature of the specific synodic cycle theme. That theme will unfold until the two planets align again, marking the completion of the synodic cycle and the beginning of the next one. The synodic theme can be thought of as expressing through the Earth-planet relationship (much like the nature of their conjunction) and then unfolding in a cycle of growth in human consciousness through a progression of aspects.

Because the Earth and each planet orbits the Sun at different rates of speed, the duration of the synodic cycle between the Earth and each planet is unique as is the location in the ecliptic where each synod occurs.

There are many synodic cycles with unique astrological themes occurring simultaneously creating a harmonic symphony of creative unfoldment in consciousness. This synodic symphony provides an underlying astrological context guiding our evolution.

Note to astrologers:

When a planet and the Sun are opposite in a geocentric chart (excluding Mercury or Venus), this is the same as seeing the Earth and the planet conjoined in a heliocentric chart (a chart which views the planets from the Sun's perspective.) This is when the Sun, Earth, and planet align. Thus, the geocentric opposition marks the beginning of the planet's synodic cycle. The star alignments of the planet reveal the planetary theme at the moment, and that of the synodic cycle to follow. The star alignments for the planet in the geocentric chart will be the same as those for the Earth-planet conjunction in the heliocentric chart. When a planet is opposite the Sun in a geocentric chart, think of that planet as conjoined Earth! (There is more on this topic below.)

When Mercury or Venus is involved, because their orbits lie inside that of Earth's, we see the Sun and the retrograde planet conjoined in the geocentric chart. And, we see the Earth and the planet conjoined in the heliocentric chart. But now, in the geocentric chart, the star alignments that lie opposite the planet-Sun conjunction are those that define the new synodic cycle. These will be the same stars of the planet-Earth conjunction as seen in the heliocentric chart. Thus, in the geocentric chart, the stars of a planet-Sun conjunction and those opposite the conjunction are both of significance when we have a retrograde Mercury-Sun conjunction or a retrograde Venus-Sun conjunction.

(Note: Not all astrological programs will generate a sidereal heliocentric chart.)

Planetary Retrogrades in the context of Synodic Cycles

Any Earth-planet synodic cycle begins during a planet's retrograde. A retrograde occurs only looking from Earth's view (geocentric). A retrograde is seen when a faster moving planet catches up to and passes a slower moving planet during their orbits around the Sun. This is when the Sun-Earth-planet alignment occurs that creates the start of the new synodic cycle—as seen from the Sun's view. It is also when Earth and the planet are closest in their orbits, which is also when the planet appears to be the largest in the sky (excepting Mercury and Venus because they lie between the Earth and Sun—thus they are not visible).

Venus retrograde

The Venus Retrograde

The above illustration shows when a Venus retrograde occurs. From Earth's view, planets normally appear to move east to west (right to left in the illustration) in the backdrop of the heavens. When the yellow line tilts left to right, Venus begins to overtake Earth in their respective orbits. This is the time when we experience a Venus retrograde. That is, from Earth's view, it appears that Venus is moving in the opposite direction in the heavens, from west to east (left to right in the illustration).

To learn more about the fundamentals of retrogrades also visit the Venus page.

Thus, a retrograde period of a planet marks the time when we disengage from a planet's previous synodic cycle and engage in its next one. The first part of the retrograde period is a time of disengagement, of letting go of previous cycle of growth (that associated with the previous planetary synodic theme). The second half of the retrograde is when we become conscious of and start to integrate the new cycle of growth (that associated with the new synodic theme). We move forth fully engaged in the new theme when the planet completes its retrograde and returns prograde (direct).

Synodic cycles and retrogrades

Planetary synodic cycles create a continuous spiral of growth, with the retrogrades making the times when we shift from one octave to another within that spiral of growth. Retrograde periods provide the opportunity to redefine the corresponding psychophysiological (mental-emotional-physical) facet of our selves that the planets resonate with. During the retrograde period, lower-order patterns within ourselves can surface to be released so we can then engage in the new octave of growth to follow.

If we have difficulty with a specific planet during its retrograde, it is often because we have resistance to let go, to redefine our lives, a fear of changing, moving on, growing. Mercury retrogrades provide a good example. How many times do you hear someone say: "I hate when Mercury is retrograde." The difficulty with Mercury retrogrades are more obvious because it often involves relinquishing modes of thinking, of how things are or "should" be—something many people have difficulty doing. They can also provide opportunity to change the daily logistics in our lives.

Synodic Astrology in a Natal Chart

Exploration of planetary placements and their aspects in the context of synodic cycles and their themes can reveal a far more embracing astrological context underlying the natal chart since the natal chart is a punctual moment, a snapshot, occurring within the synodic symphony expressing the evolutionary unfoldment of human consciousness, which synodic cycles reveal.

Natal Retrogrades and Synodic Cycles

If there is a retrograde planet in a natal chart, it can be quite revealing to explore the theme of the synod cycle that occurs during that retrograde as well as the previous synodic cycle theme (which started during the previous retrograde). Considering the retrograde planet in the embracing context of the change from one synodic cycle to another can shed light on how a retrograde planet in a natal chart reveals how a person is shifting / redefining the expression of that particular planet / dynamic of self in life.

Since the ecliptical location of the actual synod of the retrograde planet may be different than the location of the retrograde planet at the time of birth, it is well worth exploring where the synod occurs in the chart, especially if it resides at a significant location in the chart; i.e., on an angle or conjoined another natal planet. This type of exploration can bring a far deeper understanding of the nature of a retrograde planet in a natal chart.

Natal Aspects and Synodic Cycles

The planetary placements in a natal sidereal heliocentric chart, their aspects, and the timing of the planetary cycles those aspects reveal, delineate the transcendent evolutionary opportunity for the soul, which articulates through the natal sidereal geocentric chart as soul's manifest experience in form on Earth.

For example, consider that you have Jupiter approaching its first square to Saturn in a geocentric chart. The time leading into a first square in any cycle expresses as "stimulus to action." The Jupiter star alignments and the Saturn star alignments reveal the nature of this stimulus. The Jupiter energetic delineates mobilization and expansion toward a greater truth, expression of your greater wisdom, etc. (all that the Jupiter energetic delineates). The Saturn energetic brings context to Jupiter's stimulus to action, impelling mobilization and expansion from the established conformity and constructions of the past, etc. (all that the Saturn energetic delineates).

Now, if you search back in time to when Jupiter and Saturn conjoined in the heliocentric chart, you will find when and where the Jupiter-Saturn cycle began, which is the Jupiter-Saturn synod. The star alignments of the synod reveal the theme of that specific Jupiter-Saturn cycle. This brings embracing evolutionary context to the "stimulus to action" that your Jupiter-Saturn geocentric square impels.

If for example your Saturn is in sidereal Aquarius and your Jupiter is in sidereal Taurus in your geocentric chart, you would naturally look at those planets in the context of those signs and the stars expressing through their placements in those signs. However, looking back in time to the Jupiter-Saturn synod, you would find it occurred in late sidereal Sagittarius, and of course with entirely different star alignments. Thus the Saturn-Aquarius / Jupiter-Taurus geocentric square nests within the Jupiter-Saturn-Sagittarius cycle and its theme. This brings far greater context to the square, and to your stimulus to action, that you would not even be aware of when looking at your geocentric alignments alone.

Synodic Cycle Durations

Because Mercury orbits the Sun faster than Earth does, the Mercury Synodic cycle is the shortest (averaging 116 Earth days). The orbital rate of Mars is much closer to that of Earth, thus it takes longer for the Earth and Mars to re-align. Slow moving planets like Uranus, Neptune, and Pluto have cycles close to that of Earth's year because Earth catches up to those planets before they have moved very far in their orbits.

Planetary Synodic Cycle Lengths
(Average length in Earth Days)

















A graphic timeline of Planetary Synodic Cycles.
This timeline shows the inter-relationship
between each planetary synodic cycle.

Synodic Tables

Synodic Cycles of the Planets: revealing the dates
of each synodic cycle, their sidereal locations, and links to
monthly Lunar Planners where their themes are presented.

Outer Planet Synodic Timeline

Synodic Cycles of the Outer Planets: Jupiter through Pluto, and Eris: 1940-2040

Synodic Cycles Between Other Planets

Synodic cycles occur not only with the Earth and a planet, but with any set of planets. When we say a "Venus Synodic Cycle," we are referring to a cycle created by Earth and Venus. We can also have a Mars-Saturn Synodic Cycle, or a Venus-Saturn Synodic Cycle, or a Venus-Jupiter Synodic Cycle, and so on. Thus, there are many synodic cycles occurring at the same time, all with different starting times and all with different durations, and all are cycles occurring within our solar system's grand symphony—a divine orchestration of the evolutionary unfoldment of consciousness. Like an Earth-planet synodic cycle, the star alignments, looking from the Sun toward the two conjoining planets (the heliocentric view), set the theme for any synodic cycle.

Although there are many planetary synods occurring regularly, some cycles are less than a year in duration while others take many years. Cycles created by Mercury and another planet occur within one Earth year because Mercury orbits the Sun much faster than Earth, thus conjoining the other planets quite often. Cycles created by very slow movers can take many years, like that of Uranus and Neptune for example, which has a duration of about 172 Earth years. The last Uranus-Neptune synod occurred in 1993, while the next will not occur until 2164.

In the case of Pluto, Quaoar and Ixion, the synods of these planets occur in a very irregular and interrupted fashion. Because of the accentuated elliptical orbits of these planets, their rate of movement changes greatly throughout their orbital periods. When one of these planets is furthest from the Sun in its orbit (at its aphelion), its rate of movement is the slowest. When the planet is closest to the Sun (at its perihelion), the planet moves its fastest—whipping around the Sun as if being hurled like an athlete would throw a discus. Because of the ever-changing orbital rates, one of these planets may overtake another, but then the second planet may speed up while the other slows down, allowing the second planet to overtake the first, similar to horses racing around a track, where each horse may change lead position several times as the make their way around the track. Thus, in the case of these planets, one planet may overtake the other, and vise versa as if they were competing for lead place. Because of this, a synodic cycle never has a chance to finish, bur resynchronizes and changes its theme in mid-stream.

All of the synodic cycles within our solar system created by the planets orbiting our Sun continuously formulate a symphonic expression that drives our evolutionary unfoldment. These (heliocentric-based synodic cycles) can be thought of as the longer-term backdrop themes underlying our more obvious or in-the-moment experience revealed by geocentrically-based planetary conjunctions.

The two following images show the difference between a heliocentric conjunction (synod) and a geocentric conjunction, and the shift in time between the two. In this example, all three planets move a bit further in their orbits after the synod before Mars and Jupiter conjoin from Earth's view. Thus, the synod energetic (created by the heliocentric conjunction) has a time-shifted expression on Earth. It is, however, the heliocentric conjunction that marks the start of the actual synodic cycle.

Synod - Heliocentric Conjunction

The actual synod between Mars and Jupiter.
This is a heliocentric conjunction (looking from the Sun).

Geocentric Conjunction

A Mars-Jupiter geocentric conjunction, looking from Earth.

When a synod occurs between two planets, the planetary conjunction is seen looking from the Sun's perspective. However, the conjunction of those same two planets often occurs at a different time when viewed from the Earth. Depending where Earth resides in its own orbit with respect to the other two planets, the geocentric conjunction can occur before or after the actual heliocentric synod. Thus, we can think of the heliocentric synod expressing on Earth in its own unique way and time. In addition to this different time, the star alignments of the planetary conjunction as seen from the Earth may also be quite different from the heliocentric star alignments that create the primary synodic cycle theme. Further to consider is that the conjunction as seen from Earth may involve planetary retrogrades, thus causing three triggers of the conjunction on Earth, whereas there is but one primary conjunction at the heliocentric level.

The sidereal heliocentric synod star alignments reveal the actual planetary synodic cycle theme—thus revealing the deeper transcendent nature of the cycle of growth occurring in our solar system—relative more to soul-level consciousness. The geocentric conjunction's star alignments reveal more of a surface (incarnate personality) level expression of, or an augmentation upon, the transcendent synodic theme.

Approximate Synodic cycles of Jupiter with Outer planets

Jupiter-Saturn: 20 years (19.859 yrs)
Jupiter-Uranus: 14 years
Jupiter-Neptune: 13 years
Jupiter-Pluto: 12-years

Note: The actual length of a cycle can vary around its average time depending on the eccentricity of a planet's orbit and a planet's changing velocity during its orbit.

Current Jupiter-Saturn Synodic Cycles


Sidereal Heliocentric Location

Influencing Stars

Nov 15, 1940

~18° Aries

Mu Ceti (the head of Cetus), Almach Andromeda, Beta & Gamma Triangulum

April 16, 1961

~29° Sag

Theta Sag, Delta Aquila, Peacock Pavo

April 16, 1981

~13° Virgo

Diadem Coma, Porrima & Vindemiatrix Virgo

June 23, 2000

~27° Aries

Botein Aries, Omi & Xi Taurus, Rana & Zaurak Eridanus

Nov 2, 2020

~7° Cap

Altair Aquila, Alberio Cygnus, etc. (Natal U.S. Pluto)

See 2020: Jupiter, Saturn & Pluto

Dec 7, 2040

~21° Virgo

Theta Virgo and the stars of Corvus, Seginis and Muphrid Bootes

Synods in Your Natal Chart

This is but one consideration in synodic astrology, but one that is fundamental. Note where a synod occurs (in a heliocentric chart). Find this location in your natal (geocentric) chart (or that of a nation, etc.). Note the location (house) where it occurs in your chart. This defines the area of life where this synod most directly effects your life experience. The synod and its entire cycle will be especially significant if it conjoins a planet or personal point. The influence will continue throughout the entire synodic cycle and it may influence major life changes and periods your life.

Synodic Astrology: Think Planetary Cycles not just Aspects
Aspects are Phase Changes occuring in a Synodic Cycle

In conventional astrology, aspects are generally seen as events that come and go (and sometimes considered as either good or bad, malevolent or beneficent). When we look at aspects as harmonic transition points occurring in planetary synodic cycles of growth we see them in a much broader light. Aspects mark the transition from one phase of growth to the following phase of growth, phases occurring in a greater life cycle. It is also important to realize that the characteristic of an approaching aspect is different than the characteristic just after the aspect.

A "NEW" synodic cycle begins when two planets conjoin when looking from the Sun. The cycle continues as the planets orbit the Sun and until the two planets conjoin again. The first quarter (90°) square occurs when the faster moving planet is 90° from the slower moving planet. The synodic opposition occurs when the faster moving planet is 180° from the slower moving planet. At this time the two planets are on opposite sides of the Sun. The last quarter (270°) square occurs when the faster moving planet is 270° from the slower moving planet (90° to the next synod).

Jupiter-Saturn Synodic Cycle

Example of the four primary phase transitions occurring in a synodic cycle.
The Synod, the 90° square, the 180° opposition; and the 270° square.

When a planet (exclude the inner planets, Mercury and Venus for the moment) lies opposite the Sun in a geocentric astrology chart, a new Earth-planet synodic cycle begins. This is because Earth and planet conjoin when looking from the Sun, the time of their synod. This is much like a New Moon in the lunar cycle, where the new cycle's theme begins to emerge and unfold. Thus, think of a Sun-planet opposition (in a geocentric chart) as the "dark time" (like the dark New Moon), when a new theme just begins to emerge regarding that planet's expression in our Earthian experience. The Sun-planet "opposition" can feel like a challenge of opposing forces because it is when an entire cycle ends and a new theme is about to begin in our process of growth, one still unseen. As we approach the geocentric opposition (the new synod), we are letting go of the previous synodic cycle, thus this is a time of surrender, with need to let go. Just after the opposition (synod), we are engaging in the new synodic cycle, thus a time to be open to the new theme, which is just starting to emerge into our awareness.

Harmonic Families

When Earth makes its first (90°) square from the other planet (as seen in the heliocentric chart), this is much like the First Quarter Moon in lunar cycle, which creates an "external stimulus to initiate action" in the context of the original Earth-planet synodic cycle's theme. Note: the time of the squares in the synodic cycle are not obvious in a geocentric chart as they are in the heliocentric chart.

The trine (120°), which had been merely a good or easy aspect, one providing opportunity, now becomes either a portal of coming together, of intermixing, or an opportunity to give away, a time to share. The first trine (120°)—one planet separating from another planet—creates a magnetic attraction, a time of receiving, it is a time of connecting, of coming together in an alchemical mixing to become more than one could be alone.

When Earth and the planet lie opposite in the heliocentric chart (180°) (when the planet and Sun conjoin in the geocentric chart), this is much like the Full Moon in the lunar cycle—the climax in the synodic cycle. The time leading into the opposition is one of vision, enthusiasm and excitement. The time following is one of realization about the meaning of the synodic cycle's theme. This is why a Sun-planet conjunction (in the geocentric chart) is emblazoned, thus realizations about issues we may have surface to consciousness awareness regarding the planet and its current synodic cycle theme.

The second trine in the cycle (240°)—one planet approaching another planet—creates a magnetic release, an opportunistic time of giving forth, of sharing in demonstrable manifestation, marking the birth point in the cycle.

When Earth makes its second (270°) square to the planet (as seen in the heliocentric chart), this is much like the Last Quarter Moon in the lunar cycle, which creates an "inner need to initiate change" in the context of the original Earth-planet synodic cycle's theme. Again, the squares in the synodic cycle are not obvious in a geocentric chart.

These "aspects" (like all astrological aspects) are transition points in unfolding planetary cycles. They mark changes from one phase to another in the greater cycle, with each phase having its unique characteristic in an unfolding cycle of growth in consciousness. When we look at aspects in this way, we can see they are not good or bad, nor something that happens and is gone, but that they mark shifts in ongoing cycles of growth in our lives—cycles we can consciously understand and work with.

Again, an important point to realize (one ignored when thinking in terms of aspects alone and out of the context of the synodic cycle) is that the time immediately before an aspect is quite different than the time immediately after an aspect. The time before marks the ending of one phase in the cycle, the time after marks the beginning of a new phase in the cycle, with each phase having different characteristics in the embracing "cycle of growth." Another example: The time just before the 90° square brings an external stimulus that challenges us to move into action. Here we may deal with fears about acting, or what we are going to do with this stimulus. The time just after the 90° square is about initiating action itself. Thus to merely say an aspect is active in some orb and that it means the same thing independent of whether it is approaching the aspect or leaving the aspect, is to miss what that aspect is asking of ourselves in the context of the greater cycle in which it is occurring.

Harmonic Cycle of Growth

To learn about the changing phase characteristics of a planetary cycle, you can download the Lunar Planner Introduction PDF file. Although different aspects may be emphasized in a planetary cycle compared to the lunar cycle's "octad" (8-fold harmonic division), all cycles progressively unfold in a similar way, They are "cycles of growth in consciousness." Related Material: The Unfoldment of Number

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