Astrology as a System
Build a clear mental model of zodiacs, planets, stars, houses, charts, and timing before comparing traditions.
Astrology is not one universal technique. It is a family of traditions that map astronomical positions into symbolic frameworks. A useful chart reading therefore starts by naming its coordinate system, house system, interpretive rules, and timing method. Mixing those layers without saying so makes a reading difficult to reproduce.
This guide teaches the layers in that order. It describes astrology as a historical and interpretive practice; it does not present astrological prediction as scientifically established fact.
The six layers of a reading
- Astronomical data — a time, location, planetary longitude, and reference frame.
- Zodiac — tropical or sidereal longitudes divided into twelve signs.
- Houses — twelve areas anchored to the local horizon and meridian, or to the rising sign in Whole Sign houses.
- Symbolic factors — planets or grahas, signs, nakshatras, aspects, dignities, house lordships, and combinations.
- Derived charts and points — vargas, lots, arudhas, cuspal sub-lords, or other constructs defined by a tradition.
- Timing — transits, planetary periods, sign periods, directions, or other time-lord methods.
The same sky can produce different chart structures when two practitioners use different zodiacs or house systems. The calculation choice must be settled before interpretation begins. Swiss Ephemeris describes the underlying sidereal conversion and ayanamsa model and its independent house calculation methods.
Western, Indian, tropical, and sidereal
“Western” and “tropical” are not synonyms. Modern Western astrology commonly uses a tropical zodiac, but Western sidereal schools also exist. Indian astrology commonly uses a sidereal zodiac, while its texts and practices contain several distinct interpretive systems. Tradition describes a body of methods; zodiac describes a coordinate convention.
Start with Tropical and sidereal zodiacs, then learn the structure of Western astrology and how planets, stars, and nakshatras occupy houses and divisional charts.
Natal promise and timing
In the workflow documented here, the natal chart describes the underlying pattern and a timing method describes when parts of that pattern become relevant. A transit or dasha should not silently invent a result that has no foundation in the natal analysis. See Timing and dashas.
Compare the major systems
| System | Main emphasis | Typical timing tools |
|---|---|---|
| Parashari | Planets, house lords, dignities, aspects, yogas, and vargas | Vimshottari and other dashas, transits |
| Jaimini | Sign aspects, variable karakas, arudhas, and sign-based rules | Chara and other rashi dashas |
| KP | Cusps, star lords, sub-lords, significators, and ruling planets | Periods plus cuspal and ruling-planet judgment |
These systems share vocabulary but do not make every decision in the same way. For example, selecting Krishnamurti ayanamsa changes a coordinate setting; a KP judgment additionally requires KP's cuspal, star-lord, sub-lord, and significator rules.
What Ascendant implements
The Python library calculates sidereal charts, divisional charts, Vimshottari
periods, yogas, Ashtakavarga, and Swiss Ephemeris cusps for its supported
house-system codes. The current public chart result remains sign-based and does
not expose cusp membership. The library also exposes
jaimini_srao_7_core_v1: seven Chara Karakas, Rashi Drishti, Karakamsha,
Arudha Padas, Upapada, and raw Argala. The packaged skills use the
parashari_raman_jaimini_v3 hierarchy, comparing selected Parashari and
Jaimini natal factors before varga, Vimshottari, transit, and SAV layers.
The skills do not implement Chara Dasha, every Jaimini lineage, or a KP interpreter. The exact supported Jaimini core is described on the Jaimini page; other material remains educational.