The moving sky
Planetary Transits in Astrology
A transit compares a planet's current zodiacal position with a natal position or house. Begin by naming the moving planet, the natal point it contacts and the angle between them. Those are three different pieces of information.
Understand the idea
Transits: comparing the moving sky with a birth chart
A birth chart records positions for a particular moment; a transit reading compares that fixed reference with the sky at another time. The moving planet can pass through a natal house or form an aspect to a natal planet or angle. This is why a transit needs both a date and a specific birth-chart reference to be meaningful.
Astrologers use the comparison to explore themes that may be worth attending to during a period. Saturn contacting Mercury might prompt reflection on commitments, study or careful communication; Jupiter contacting Venus might prompt questions about enjoyment, generosity and expectations. These are interpretive topics, not a timetable of events that every person with the contact will experience.
Separate the moving planet's role from the natal point it meets. Then check the angle, orb and dates of exact contact. A repeated pass can give a reading a beginning, middle and later review, but the practical story comes from what is happening in your life. A transit is most useful as a way to organise reflection alongside real plans and circumstances.
An illustrative example
A worked example: transiting Saturn at 15° Pisces opposite natal Mercury at 15° Virgo
This is an exact 180° contact. An astrologer might discuss reviewing commitments, concentrating on study or being more careful with words. Those are possible themes to reflect on, not predictions of bad news.
This is a fictional example to explain the idea, not a prediction or a client case study.Put it into practice
A question to take with you
Choose one transit and record its exact dates from an ephemeris. Keep notes on ordinary events as well as striking ones, so you do not only notice what matches the interpretation.
Frequently asked questions
Why can the same transit happen more than once?+
Apparent retrograde motion can carry a planet back across a natal degree before it moves forward over it again. Check the actual path: not every transit has three passes.
How do I identify the moving planet and the natal planet in a transit description?+
In transiting Saturn opposite natal Mercury, Saturn supplies the current position and Mercury supplies the fixed birth position. Write both degrees and the aspect angle. Reversing the roles describes a different transit.
Why can a slow-planet transit stay relevant longer than a Moon transit?+
Apparent speed determines how long a planet remains near the chosen aspect orb. Slow planets can spend more time near a natal degree and may revisit it. A timing window is not a promise of continuous events.
How can I find out whether a transit will make one pass or several?+
Check an ephemeris across the full relevant period, including stations and retrograde motion. List each exact crossing of the natal degree. Do not assume that every transit has a standard three-pass sequence.
Can I interpret transits to houses if my birth time is uncertain?+
Be cautious because house boundaries and angles depend on birth time. You may be able to examine contacts to some natal planets, while treating house-based timing as uncertain. Check the possible birth-time range rather than selecting one convenient version.
Reading notes
These guides use Western astrological symbolism, with tropical signs and a distinction between traditional rulerships and modern associations. Interpretations vary between schools. A calculated position is an astronomical measurement; its suggested personal meaning is an interpretation.
Further reading: Astrodienst on aspects and NASA's illustration of apparent retrograde motion. These explain different subjects: astrological angles and observed planetary motion.
Explore more aspects & transits
Try it with your chart
Find the placements you have been reading about.
Keep this guide nearby as you explore your own signs, houses and aspects.