AI Astrology Assistant
Build an astrology assistant that computes birth charts with the same logic as professional tools (e.g. Astro-Seek). Use Swiss Ephemeris (or pyswisseph, swephR, swisseph-js) as the calculation engine.
When to Apply This Skill
- User asks for birth chart calculation, natal chart, or horoscope by birth data
- Building an astrology API, chatbot, or web calculator
- Interpreting planetary positions, houses, or aspects
- Implementing ephemeris-based astrology features
Core Workflow
1. Parse birth data (date, time, location) → validate inputs
2. Convert local time → UTC → Julian Day
3. Compute planetary positions (swe_calc_ut)
4. Compute houses, Ascendant, MC (swe_houses)
5. Assign planets to houses (swe_house_pos)
6. Calculate aspects between all pairs
7. Optionally apply sidereal ayanamsha
8. Format and interpret results
Required Inputs
| Input | Required | Notes |
|---|---|---|
| Date of birth | Yes | Day, month, year |
| Time | No* | Local time (h, m, s). *Required for houses/Ascendant |
| Birth place | Yes | City name or lat/long |
| Timezone | Yes | Auto from location or manual (e.g. UTC+1) |
| DST | Yes | Observed / Not-Observed |
| House system | No | Default: Placidus |
| Zodiac | No | Default: Tropical |
Implementation Checklist
1. Time Conversion
# Local → UTC (apply timezone + DST)
# UTC → Julian Day
jd_ut = swe_utc_to_jd(year, month, day, hour, min, sec, SE_GREG_CAL)
# Returns: dret[0]=JD_TT, dret[1]=JD_UT
2. Planetary Positions
# For each body: Sun(0), Moon(1), Mercury(2)... Pluto(9), Node(10/11), Chiron(12), Lilith(15)
ret, xx = swe_calc_ut(jd_ut, planet_id, SEFLG_SWIEPH)
# xx[0]=longitude, xx[1]=latitude, xx[2]=distance, xx[3]=speed (retrograde if < 0)
3. Houses
# Requires: jd_ut, latitude, longitude, house_system
cusps, ascmc = swe_houses(jd_ut, lat, lon, hsys)
# cusps[1..12] = house cusps, ascmc[0]=Ascendant, ascmc[1]=MC
4. House Assignment
house = swe_house_pos(armc, lat, obliquity, hsys, [lon, lat])
5. Aspects
Compute angular distance between each planet pair. Aspect is valid if |distance - aspect_angle| <= orb.
| Aspect | Angle | Default orb |
|---|---|---|
| Conjunction | 0° | 8° |
| Opposition | 180° | 7° |
| Trine | 120° | 6° |
| Square | 90° | 6° |
| Sextile | 60° | 4° |
6. Sidereal (Optional)
swe_set_sid_mode(ayanamsha_type) # e.g. SE_SIDM_LAHIRI
# Then swe_calc_ut returns sidereal positions
# Or: sidereal_lon = tropical_lon - swe_get_ayanamsa_ut(jd_ut)
Output Format
Present results as:
- Planet table: Planet | Sign | Degree | House | Retrograde
- House cusps: ASC, MC, and houses 1–12
- Aspects list: Planet A – Aspect – Planet B (orb)
- Special points: Part of Fortune, Vertex, Nodes, Lilith (if enabled)
Key Constants
- Planet IDs: Sun=0, Moon=1, Mercury=2, Venus=3, Mars=4, Jupiter=5, Saturn=6, Uranus=7, Neptune=8, Pluto=9, MeanNode=10, TrueNode=11, Chiron=12, MeanLilith=15
- House systems: P=Placidus, K=Koch, R=Regiomontanus, C=Campanus, E=Equal, W=Whole Sign
- Zodiac signs: 0°=Aries, 30°=Taurus, 60°=Gemini... 330°=Pisces
Part of Fortune
Diurnal (Sun above horizon): Fortune = ASC + Moon - Sun
Nocturnal (Sun below horizon): Fortune = ASC + Sun - Moon
Error Handling
- Unknown birth time: Compute chart without houses; use noon or offer "chart for date only"
- Invalid coordinates: Reject or use fallback (e.g. capital city)
- Polar latitudes: Placidus fails; suggest Equal or Whole Sign
- Date out of range: Swiss Ephemeris covers ~13,000 years; validate 1800–2100 for typical use
Dependencies
- Python:
pyswisseph+ ephemeris files (download from astro.com) - Node.js:
swissephorastronomia - R:
swephR
Set ephemeris path: swe_set_ephe_path("/path/to/ephe")
Reference & Examples
- Full API specs, formulas, ayanamshas: reference.md
- User flows, response formats, edge cases: examples.md