What a transit is, and why today is not your chart

By Ines Vasquez

A transit is where a planet actually is in the sky right now, measured against where the planets were when you were born. Your birth chart never changes. The sky keeps moving. A transit is the angle between the two — today's Mars arriving at the degree your natal Venus has occupied since the day you arrived. Astrology reads the meeting, not either half alone.

What is a transit in astrology?

A transit is the current position of a planet compared to a fixed point in a birth chart. The word comes from the Latin transitus, a crossing over: the planet crosses a degree of the zodiac that already means something to you personally.

Two charts are involved, always. The first is the natal chart, a map of where the planets stood at the moment and place of your birth, which is fixed permanently and does not update. The second is the sky as it is at this moment, sometimes called the transiting chart or simply the ephemeris positions — an ephemeris being a table of planetary positions by date, the same kind of table navigators once used.

When astrologers say "Saturn is transiting your Moon", they mean Saturn's current position in the zodiac has arrived at the same degree where your natal Moon sits. The natal Moon has not moved. Saturn has. Everything a transit is held to describe comes from that arrival, and from the particular character the tradition assigns to the arriving planet.

Why isn't my horoscope just my birth chart?

Because a birth chart describes a pattern and a horoscope describes a moment, and the two answer different questions.

The natal chart is read as the standing shape of a person: the disposition, the recurring preoccupations, the way somebody tends to go about things. It is the same at forty as it was at four. Nothing in it expires.

A transit is weather passing over that landscape. The same rainfall does very different things to a floodplain and to a hillside. This is the distinction most daily horoscopes lose entirely, because a sun-sign column has access to only one piece of your natal chart — the sign your Sun was in — and has to write as though that single fact were the whole map. It cannot know where your Moon is, where your Saturn is, or what house the transiting planet has walked into for you specifically.

A serious transit reading needs both halves. Without the natal chart, a transit is a weather report for nobody in particular.

How do astrologers say transits work?

Astrologers hold that a transiting planet activates the natal point it contacts — that the natal placement describes a standing theme and the transit describes a period when the theme becomes loud. The mechanism claimed is symbolic correspondence rather than physical influence, and no physical mechanism has been demonstrated. Ptolemy in the second century attempted a physical account in the Tetrabiblos, arguing from heat and moisture; almost no practising astrologer defends that account now.

What is astronomically true, and can be stated flatly:

The planets are where the tables say they are, to a high precision, and have been calculable for centuries.
A transit is a matter of geometry — the angular distance between a moving body and a fixed degree.
The speed of each planet determines how long a transit lasts, and that is arithmetic, not opinion.

What is interpretation, and should be held as such:

That a Saturn transit correlates with a period of pressure, consolidation or reckoning.
That a Jupiter transit correlates with expansion or the loosening of a constraint.
That the natal placement receiving the transit shapes what the pressure or the loosening is about.

The humanistic school, which Dane Rudhyar began building in the 1930s and which the evolutionary astrologers extended from the 1970s and later Jeffrey Wolf Green, adds a further claim: that the same transit recurring across a life tends to find the person at the same unfinished piece of business. That claim about recurrence is where the tradition is most interesting and least testable.

How long does a transit last?

Length depends entirely on the planet's orbital speed and on whether it turns retrograde, appearing from Earth to move backwards against the stars. Faster planets produce brief transits; the outer planets can hold a single natal degree for a year or more.

Planet	Full circuit of the zodiac	Typical transit to one natal point
Moon	about 27.3 days	a few hours
Sun	one year	about two days
Mercury	about one year (orbits in 88 days)	days, longer if it stations retrograde
Venus	about one year (orbits in 225 days)	days to a week
Mars	about two years	a week, or months if retrograde
Jupiter	about twelve years	two to four weeks per pass
Saturn	about 29.5 years	several weeks, repeated over a year if retrograde
Uranus	about 84 years	months, often three passes across a year
Neptune	about 165 years	a year or more
Pluto	about 248 years	one to two years, sometimes longer

Mercury and Venus never stray far from the Sun as seen from Earth — Mercury a maximum of about 28 degrees, Venus about 47 — which is why they always transit in the Sun's rough vicinity.

The triple-pass pattern matters. An outer planet frequently crosses a natal degree, turns retrograde and crosses back, then turns direct and crosses a third time. Astrologers read the three passes as one extended episode rather than three unrelated ones: the first pass raising the matter, the retrograde pass revisiting it, the direct pass settling it. The three-pass structure is astronomy. The narrative arc laid over it is interpretation, and a twentieth-century one.

Which transits are considered important?

Transits are ranked by three things: the speed of the transiting planet, the angle it makes, and what it lands on.

Speed. The slow planets — Saturn, Uranus, Neptune, Pluto — are treated as the significant ones, because they stay long enough for something to develop. The Moon transits every degree of your chart every month and is read as passing mood, emotional weather rather than climate. Nobody's life turns on a Moon transit.

Angle. The classical aspects, set out in their essentials by Ptolemy and standard in the tradition ever since:

Aspect	Angle	How it is read
Conjunction	0°	fusion; the transit's most direct contact
Sextile	60°	opportunity requiring participation
Square	90°	friction, the classical "hard" aspect
Trine	120°	ease, sometimes read as too easy to notice
Opposition	180°	tension held between two poles

The orb — the margin of error allowed around an exact angle — is disputed. Traditional practice allowed generous orbs; a good deal of modern practice tightens them to a degree or two for transits, on the grounds that a transit felt within eight degrees is a transit felt all the time.

What it lands on. A transit to the Sun, Moon or Ascendant is read as more personal than a transit to a slow natal planet, because those three describe the identity, the emotional life and the way you meet the world. A transit to an angle — the Ascendant, Descendant, Midheaven or Imum Coeli — is likewise treated as prominent. Note that angles and houses depend on the exact birth time, and that house positions shift depending on which house system is used, so a transit reported as "entering your seventh house" may be a tenth-house transit under a different system.

Do transits mean the same thing for everybody?

No, and the belief that they do is the single largest distortion in popular astrology. A transit's meaning depends on what it contacts in the individual chart.

Saturn reaching 15 degrees of Libra is one event in the sky. For a person with the natal Moon at 15 Libra it is read as a Saturn transit to the Moon — a contact with the emotional life. For a person with nothing near that degree it is read as barely anything, or only as a house transit with no planet involved. Same sky, different chart, different reading.

The one genuine exception is a transit that happens on roughly the same schedule for everyone, because it is keyed to orbital period rather than to natal position. The Saturn return, when transiting Saturn comes back to its natal degree, arrives at about 29 for everybody, and again near 59. The Jupiter return recurs every twelve years. Some of the nodal cycle works the same way: the lunar nodes, the two points where the Moon's orbit crosses the ecliptic, complete a circuit in about 18.6 years, which puts the nodal return at roughly 19, 37 and 56 regardless of who you are.

Those age-keyed transits are the reason certain ages feel collectively significant. They are not the reason a Tuesday feels the way it does. For that, the tradition asks you to know where the sky is standing in relation to your own chart, which is a different question from where the sky is standing.