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Transits

The transit system evaluates the effects of current planetary positions on the natal chart. Two modules work together: transits (position mapping) and transit_effects (interpretation).

Overview

Transit analysis compares where planets are now against where they were at birth to derive effects, timing themes, and intensity levels.

Position Mapping (transits module)

get_rasi_index

get_rasi_index(longitude: float) -> int

Converts an ecliptic longitude (0–360°) to a rasi (sign) index (0–11, where 0 = Aries).

get_house_index

get_house_index(longitude: float, lagna_longitude: float) -> int

Computes the house number (1–12) a planet occupies relative to the ascending degree.

build_transit_positions

build_transit_positions(
    current_planets: list[Planet],
    natal_lagna_longitude: float
) -> dict[str, TransitPosition]

Maps each transiting planet to its current house and sign relative to the natal ascendant.

build_house_transits

build_house_transits(
    current_planets: list[Planet],
    natal_lagna_longitude: float
) -> dict[int, list[str]]

Returns a mapping of house number → list of transiting planet codes currently in that house.

calculate_transit_aspects

calculate_transit_aspects(
    current_planets: list[Planet]
) -> list[TransitAspect]

Calculates aspects currently formed between transiting planets.

calculate_aspects_to_natal_planets

calculate_aspects_to_natal_planets(
    current_planets: list[Planet],
    natal_planets: list[Planet]
) -> list[NatalTransitAspect]

Calculates aspects formed between current transiting positions and natal planet positions. Includes special Mars/Jupiter/Saturn aspects.

classify_transit_house

classify_transit_house(house: int) -> TransitHouseClass

Classifies the transit house by its functional category.

TransitHouseClass Values

Value Houses Meaning
KENDRA 1, 4, 7, 10 Angular — strong and immediate effects
TRIKONA 1, 5, 9 Trinal — fortune and dharma
DUSTHANA 6, 8, 12 Difficult — challenges, obstacles, loss
UPACHAYA 3, 6, 10, 11 Growing — beneficial over time
MARAKA 2, 7 Marker of endings and transformation
NORMAL 2, 3, 11 General areas of life

get_house_transit_interpretation

get_house_transit_interpretation(
    planet: str,
    house: int
) -> str

Returns the classical textual interpretation for a planet transiting a given house.

Transit Effects (transit_effects module)

interpret_transit

interpret_transit(
    planet: str,
    house: int,
    *,
    is_retrograde: bool = False
) -> TransitInterpretation

Returns a structured interpretation for a single planet's transit through a given house.

Returns: TransitInterpretation with:

Field Type Description
planet str Planet code
house int Transit house (1–12)
impact TransitImpact Impact level
theme str Life area theme
description str Narrative description
is_retrograde bool Retrograde modifier applied

analyze_transit_effects

analyze_transit_effects(
    transiting_planets: dict[str, int],
    *,
    retrograde_planets: set[str]
) -> list[TransitEffect]

Bulk analysis — evaluates the transit effects of all planets simultaneously.

Parameters:

Parameter Type Description
transiting_planets dict[str, int] Planet code → current house number
retrograde_planets set[str] Set of planet codes currently retrograde

TransitImpact Enum

Value Meaning
VERY_FAVORABLE Major positive outcomes
FAVORABLE Positive, supportive
NEUTRAL Neither positive nor negative
CHALLENGING Obstacles and friction
VERY_CHALLENGING Major disruption or difficulty

House Transit Themes

Each house area of life that transiting planets activate:

House Theme
1 Self, health, new beginnings
2 Finances, speech, family
3 Courage, siblings, communication
4 Home, mother, emotions
5 Children, creativity, education
6 Health, service, enemies
7 Partnerships, marriage, contracts
8 Transformation, longevity, hidden matters
9 Dharma, spirituality, father, travel
10 Career, authority, public reputation
11 Gains, networks, aspirations
12 Losses, liberation, foreign lands

Sample Usage Flow

# 1. Get current planetary positions
current = get_sidereal_planet_positions(lat, lon, now, ayanamsa)

# 2. Map to houses relative to natal lagna
houses = build_transit_positions(current, natal_lagna_longitude=95.3)

# 3. Classify and interpret each
effects = analyze_transit_effects(
    transiting_planets={p.code: p.house for p in current},
    retrograde_planets={p.code for p in current if p.retrograde}
)