The Moving Sky: Understanding Secondary Progressions and the Fixed Stars
There is a peculiar tension at the heart of astrology that most people never think about. On the one hand, you have your birth chart: a frozen snapshot of the sky at the moment you drew your first breath. On the other, you have the undeniable fact that you are not the same person at forty that you were at four. The birth chart captures the seed. But what about the tree?
This is where progressions enter the picture. And once you begin to explore them, you inevitably stumble into a much older and more fascinating question: what exactly is the relationship between the zodiac signs we use in astrology and the constellations they were named after? The two topics are more deeply entwined than they might first appear.
A Day for a Year: The Logic Behind Progressions
The technique most commonly referred to as "progressions" is, more precisely, secondary progressions. The principle is elegantly simple. Each day after your birth is taken to symbolically represent one year of your life. So the positions of the planets on your thirtieth day of life correspond to themes and energies unfolding during your thirtieth year. The Sun on your forty-fifth day after birth maps onto your forty-fifth year, and so on.
The idea has a surprisingly ancient pedigree. While secondary progressions are typically attributed to the 17th-century Italian monk and mathematician Placidus de Titis, the concept actually appears in the work of Vettius Valens, a 2nd-century Hellenistic astrologer working in Alexandria. In Book IX of his Anthology, Valens described a method of adding the native's age in days to the birth date and examining the planetary positions on that resulting date. His treatment was brief, and the technique appears not to have been widely adopted in antiquity, but it demonstrates that the symbolic equation of a day with a year was being explored a full 1,500 years before Placidus formalised it.
The older cousin of secondary progressions is primary directions, a technique rooted in the daily rotation of the Earth on its axis. Primary directions were the dominant forecasting method from Ptolemy through to the Renaissance. Their calculations involve spherical trigonometry, which made them laborious before computers, and they gradually fell out of common use in favour of the more accessible secondary progressions. The distinction between "primary" and "secondary" reflects these two fundamental celestial motions: the Earth's daily spin (primary) and the movement of planets through the zodiac over time (secondary).
What Moves, and How Fast?
In a progressed chart, the fast-moving bodies are the ones to watch. The progressed Sun advances at roughly one degree per year, meaning it takes approximately thirty years to traverse a single zodiac sign. Most people will experience their Sun progressing through only two or three signs in an entire lifetime. The progressed Moon, being far quicker, shifts through a sign in about two and a half years and completes a full cycle of the zodiac in roughly twenty-seven to twenty-eight years.
Mercury, Venus, and Mars also move meaningfully in the progressed chart, though their rates vary. The outer planets (Jupiter, Saturn, Uranus, Neptune, and Pluto) are so slow that they barely shift at all by secondary progression in a normal lifespan, which is why astrologers tend to focus their attention on the personal planets and the angles of the chart (particularly the Ascendant and Midheaven).
One of the more striking features of progressions is what happens when a progressed planet changes sign. When your progressed Sun shifts from, say, Virgo into Libra, advocates of this technique describe a tangible reorientation. Priorities that seemed fixed begin to soften or redirect. The American astrologer Steven Forrest has written vividly about his own experience of progressed sign changes, describing how his Sun's move from Aquarius into Pisces in 1992 brought a shift from intellectual defensiveness about astrology to a more relaxed, spiritually open approach to his work.
The Progressed Moon: A Shorter Rhythm
If the progressed Sun tracks the broad arc of your evolving identity, the progressed Moon charts something more immediate and intimate: your shifting emotional needs. Those roughly two-and-a-half-year periods during which the progressed Moon occupies each sign are thought to describe distinct emotional chapters. Moving from a water sign to a fire sign, for instance, might coincide with a shift from introspection to restless action. From earth to air, you might feel a pull away from material concerns toward social or intellectual ones.
The full cycle of the progressed Moon, returning to its natal position after about twenty-seven years, is sometimes called the Progressed Lunar Return. The first return around age twenty-seven or twenty-eight often coincides with a felt sense of entering true adulthood. The second, around age fifty-four, tends to mark a quieter but equally significant turning point, where questions of legacy and deeper purpose come into focus.
The Constellations Behind the Signs
All of this talk about signs progressing through the zodiac raises an important question that sits at the intersection of astronomy and astrological philosophy. When we say the progressed Sun has moved into Libra, what do we actually mean by "Libra"? Are we talking about the constellation, that grouping of stars in the night sky? Or something else entirely?
The answer cuts to the heart of one of the most misunderstood aspects of Western astrology.
The zodiac has its origins in ancient Babylon. By around the end of the 5th century BCE, Babylonian astronomers had divided the ecliptic (the apparent path of the Sun across the sky) into twelve equal segments of thirty degrees each. These segments roughly corresponded to twelve prominent constellations that lay along the ecliptic, and were named for them: the Ram, the Bull, the Twins, and so on. The word "zodiac" itself comes from the Greek zodiakos kyklos, meaning "circle of little animals", reflecting the prevalence of animal imagery among the signs.
Here is the critical point: the constellations themselves are not equal in size. Some span far more than thirty degrees of the ecliptic, others far less. The Babylonians, in creating the zodiac, imposed a mathematical regularity onto an irregular sky. They created an idealised framework, a cosmic ruler, that only approximately lined up with the star patterns it was named for.
The Great Drift
Things get more complicated still. The Earth does not spin perfectly upright. Its axis wobbles slowly, like a top that is starting to wind down. This wobble, known as axial precession, was first observed by the Greek astronomer Hipparchus around 129 BCE. He noticed that the positions of stars had shifted systematically since the Babylonians had catalogued them centuries earlier, and correctly deduced that it was the observing platform, the Earth itself, that was moving.
The full cycle of this precession takes approximately 25,772 years. During that time, the point where the Sun crosses the celestial equator at the March equinox (the vernal point) slowly drifts westward through the background constellations. Roughly 2,000 years ago, the vernal equinox fell in the constellation of Aries. Today, due to precession, it falls in Pisces. The rate of drift is about one degree every seventy-two years, or fifty arc-seconds annually.
This means that the zodiac signs, as used in Western astrology, no longer align with the constellations they were originally named after. A person born when the Sun is said to be "in Aries" by the tropical zodiac (the system used by most Western astrologers) actually has the Sun positioned against the backdrop of the constellation Pisces. The gap between the tropical sign and the sidereal constellation is currently around twenty-four degrees, and it will continue to grow.
Two Zodiacs, Two Philosophies
This discrepancy has given rise to two distinct systems. The tropical zodiac, dominant in Western astrology, anchors its signs to the seasons. Zero degrees Aries always begins at the March equinox, regardless of which constellation the Sun actually appears against. The sidereal zodiac, used primarily in Vedic (Indian) astrology, attempts to maintain alignment with the actual constellations by applying a correction factor called the ayanamsha.
Neither approach is inherently "wrong". They are measuring different things. The tropical zodiac tracks the Sun's relationship to the Earth's seasons. The sidereal zodiac tracks the Sun's position relative to the fixed stars. As the astrologer Robert Hand has argued in his paper "On the Invariance of the Tropical Zodiac", ancient astrologers drew on both tropical and sidereal reasoning, and it was only after Hipparchus publicised the existence of precession that the two approaches began to diverge into distinct traditions.
For progressions, this distinction matters. When your progressed Sun enters Libra in the tropical system, it is entering a segment of the ecliptic defined by its relationship to the autumnal equinox, not by its alignment with the stars of the constellation Libra. The sign's meaning, in this framework, derives from its position in the seasonal cycle: Libra marks the equinox, the balance point between light and dark, which is why it is associated with themes of balance, relationship, and fairness.
The Constellations as Myth
So where do the constellations fit? They are not irrelevant, but their role is different from what many people assume. The constellations provided the original imagery for the zodiac signs. The Babylonians named their twelve ecliptic divisions after the star groupings they saw there, and the Greeks wove those groupings into elaborate mythological narratives. Aries became the Golden Ram whose fleece Jason sought. Cancer was the crab that Hera sent to distract Heracles during his battle with the Hydra. Scorpio was the creature that slew Orion.
These myths gave the signs their symbolic character. But in a tropical framework, the sign's meaning is sustained by its seasonal position, not by the constellation behind it. The qualities attributed to Scorpio, for example, relate to its place in late autumn (in the Northern Hemisphere), a time of decay, depth, and transformation, rather than to the physical stars of the constellation Scorpius.
This is an important nuance for anyone working with progressions. When your progressed Moon moves through Scorpio for two and a half years, the emotional landscape being described draws on the archetypal qualities of that sign as defined by the tropical system: intensity, emotional depth, a pull toward what is hidden or taboo. The constellation Scorpius, meanwhile, continues its slow drift relative to the tropical sign, and in a few thousand years, the stars we know as Scorpius will no longer occupy the section of the ecliptic we call Scorpio at all.
Progressions and the Psychology of Growth
The psychological dimension of progressions is where things become particularly interesting for anyone drawn to the kind of integrated work practised at the Wilfred Hazelwood Clinic. Carl Jung, whose ideas underpin psychological astrology, was deeply interested in the relationship between celestial symbolism and the inner life. He wrote that astrology represents "the sum of all the psychological knowledge of antiquity", and he viewed the zodiac as a symbolic map of what he called the individuation process: the journey toward psychological wholeness.
In Jung's framework, the Sun corresponds to the conscious ego and life direction. The Moon carries the emotional body and instinctual patterns. Saturn embodies the lessons that demand maturity. These correspondences map neatly onto how progressions are interpreted. The progressed Sun, advancing slowly through the signs, can be understood as the evolving expression of the ego as it encounters new archetypal territory. The progressed Moon, cycling through the zodiac every twenty-seven years or so, traces the rhythm of emotional development, the successive chapters of what the heart needs and seeks.
Jung's concept of the shadow, the repressed or denied aspects of the self, is also relevant. When a progressed planet enters a sign whose qualities feel foreign or uncomfortable, this can be understood as an encounter with unfamiliar psychic territory. A person whose natal chart is dominated by fire and air might find the progressed Moon's passage through Cancer or Pisces disorienting, a period where emotional vulnerability and receptivity are called for, qualities that might previously have been avoided or undervalued.
The Tree Rings Analogy
One of the most helpful ways to think about progressions comes from astrologer Ada Pembroke, who compares them to the rings of a tree. Each year of planetary movement by progression adds a new layer to your chart. The earlier layers do not disappear. A person whose Sun has progressed through Capricorn and into Aquarius does not stop being a Capricorn Sun (natally). They gain an additional layer. The Capricorn discipline and structure remain as foundation, while Aquarian independence and intellectual curiosity develop on top.
This additive quality is important. Progressions do not erase the natal chart. They layer new textures and emphases over what was there at the beginning. And this is precisely why they lend themselves so well to a therapeutic context. Understanding your current progressed placements can illuminate why certain themes, emotions, or challenges feel particularly pressing right now, even when they do not obviously connect to what your birth chart alone might suggest.
Putting It All Together
The relationship between progressions and the constellations is, at its core, a relationship between time and meaning. The constellations gave astrology its foundational imagery. The zodiac signs, anchored to the seasonal cycle, gave that imagery a stable interpretive framework. Progressions provided a way to track how an individual moves through that framework across a lifetime. And precession, the slow wobble of the Earth, ensures that the constellations and the signs will continue to drift apart, generation after generation, raising questions about the nature of astrological meaning that practitioners have grappled with for millennia.
For those approaching progressions from a psychological perspective, the practical takeaway is this: the value of the technique does not depend on a literal correspondence between zodiac signs and the star patterns visible in the sky. It depends on the symbolic and seasonal logic of the tropical zodiac, a logic that has proven remarkably durable across more than two thousand years of practice. When your progressed Moon enters Sagittarius and you feel a restless hunger for travel, expansion, or philosophical exploration, you are participating in a symbolic system whose roots stretch back to ancient Babylon, but whose application is thoroughly alive and present.
At the Wilfred Hazelwood Clinic, Martyn J. Shrewsbury draws on his training in both Hellenistic astrology and Jungian psychology to work with techniques like progressions in a way that honours their historical depth while keeping the focus on practical psychological insight. If you are curious about what your progressed chart might reveal about the chapter of life you are currently navigating, get in touch to arrange a consultation.
