At a glance
- Identification point
- Actual dated positions and day-for-year mappings are different.
Definition and identification
Transits use actual computed celestial positions for a specified date and compare them with a reference chart. Progressions instead apply a symbolic mapping, such as relating days after birth to years of life, or advance chart points by other rules. Precise algorithms ensure consistency under a convention; they do not make a personal event inevitable.
Structure and reading rules
Secondary progressions commonly use one day for one year, with additional choices about the starting instant and treatment of angles. Solar-arc methods shift points by a common arc instead of moving every body at its real speed. Transit work should likewise state orbs, repeated retrograde contacts and its reference chart. These procedures should not be confused with one another.
Concrete example
Under an illustrative day-for-year rule, age twenty refers to an ephemeris twenty days after birth, not the actual sky on the twentieth birthday. A reference longitude of one hundred degrees and a transit at two hundred twenty are separated by one hundred twenty degrees. Date mapping and angular calculation can be checked without forecasting marriage, unemployment or illness.
Historical context and limits
Modern manuals separate transits from directions or progressions, showing that practitioners distinguish these timing conventions. Ancient directions and modern software defaults are not interchangeable simply because their names resemble each other. Selecting a striking aspect after an event invites selective matching. Predictive evaluation needs predefined periods, outcomes and failures as well as apparent successes.
References & further reading
Historical sources document ideas and rules of their time, not empirical proof of predictive accuracy. Source notes identify the nature and scope of each reference.
- Sepharial, Astrology: How to Make and Read Your Own Horoscope (1920)Primary / tradition source
Modern practitioner manual for chart construction and timing; its scientific and health claims are not endorsed.
- Ptolemy, Tetrabiblos, Book IIIPrimary / tradition source
Ancient natal astrology; editorial notes identify the limited treatment of houses.