🌟 Stellium

A modern, extensible Python library for computational astrology

Built on Swiss Ephemeris for NASA-grade astronomical accuracy, Stellium brings professional astrological calculations to Python with a clean, composable architecture that works for everyone, from quick scripts to production applications.

Read the extensive documentation and API autodocs at Read The Docs.

Try out some quick examples immediately, no installation needed:

Stellium The Webapp is live! Visit it here! It represents about 50-60% of the functionality of the full package, but is great for testing out the core capabilities and getting quick chart outputs.

Star the repo if you find it useful! ⭐

Why Stellium?

For Python Developers

• Fully typed with modern type hints for excellent IDE support
• Protocol-driven architecture - extend with custom engines, no inheritance required
• Fluent builder pattern - chainable, readable, intuitive API
• Flexible input formats - accepts datetime strings, city names, or precise coordinates
• Modular & composable - mix and match components as needed
• Production-ready with comprehensive test coverage

If you've used React (composable, plug-and-play components) or PyTorch (sensible defaults, progressive disclosure, lazy .calculate()), the API should feel familiar.

For Astrologers

Western:

• Large-scale data analysis with pandas DataFrames, batch calculation, and statistical tools
• 17 house systems including Placidus, Whole Sign, Koch, Equal, Regiomontanus, and more (see the full list).
• Multiple house systems in a single chart for comparison of traditions and meta-analysis
• Declination calculations with out-of-bounds planet detection and parallel/contraparallel aspects
• Bi-, tri- and quad-wheel charts for synastry, transits, progressions, returns, arc directions, and composite analysis
• Sect-aware calculations with proper day/night chart handling
• Birth-time rectification (sect) — honest, human-in-the-loop recovery of day/night sect (~70%, cross-validated) via a compare-hypothesis workbench; deliberately does not fake minute-level time (it's an ill-posed inverse). Guide
• 25+ Arabic Parts with traditional formulas (see the full list)
• Essential & accidental dignity scoring for both traditional and modern rulerships
• Fixed stars — the four Royal Stars and beyond, by tier or by name (e.g. Regulus, Algol)
• Chart rulership and profections for traditional astrology
• Dispositor graphs for planets and (experimentally) houses in reports
• Aspect pattern detection - Grand Trines, T-Squares, Yods, Stelliums, and more
• Zodiacal Releasing for 25+ lots (including Fortune and Spirit) and optional "fractal" calculation mode
• Firdaria — the Persian time-lord system with day/night sequencing, seven Chaldean sub-periods, and Abu Ma'shar / Bonatti node presets
• Length of life — the classical hyleg → alcocoden years-table (Lilly) with a fully itemized, auditable result, plus a reusable almuten-of-a-degree calculator
• Uranian astrology including Trans-Neptunian Planets and 45/90/360-degree dials with pointers.
• Primary and Zodiacal directions with 3D modeling and and distribution across bounds
• Draconic Charts and Void of Course Moon
• Transit timeline analysis - Calculate transit-to-natal aspect periods with orb entry/exit windows, retrograde multi-pass detection, plain-text list output, and SVG Gantt chart visualization
• Prompt-friendly text export - chart.to_prompt_text() generates clean markdown from any chart type, ready for LLM prompts. Handles single charts, synastry, composites, unknown-time charts, multiple house systems, and all components
• Electional astrology - Find auspicious times with 30+ predicates, interval optimization, and planetary hours
• Heliocentric positions
• Antiscia and contra-antiscia with a dedicated report section
• Beautiful visualizations with professional SVG chart rendering and 14 themes
• Beautiful Composable PDF or CLI reports to show nitty-gritty details of the chart (see this example for a subset of what's available)
• Localized reports — render terminal, Markdown, HTML, and PDF reports in multiple languages (Simplified Chinese included) via with_locale()
• Notable births database for quick exploration and learning. Check out the current list
• Notable life-event & temperament datasets — taxonomy-tagged biographical timelines (888 dated events) and character descriptors for 60+ notables, honestly provenance-graded, via get_notable_life_events() / get_notable_temperament()

Vedic:

• Both tropical and sidereal zodiacs with 9 ayanamsa systems for Vedic astrology
• North Indian and South Indian chart rendering — traditional Vedic/Jyotish chart formats with 3 themes, 4 label styles, degree display, and full native info

Chinese:

• Ba Zi system with Ten Gods and Hidden Stems

Visual Chart Example

Synastry

Report Sample Pages

Vedic Charts (North Indian & South Indian)

Transit Timeline (Gantt Chart)

Graphic Ephemeris Example

What Makes Stellium Different

Unlike other Python astrology libraries, Stellium is designed for extensibility:

# Other libraries: rigid, hard-coded calculations
chart = AstrologyLibrary(date, location)  # That's all you can do

# Stellium: composable, configurable, extensible
chart = (ChartBuilder.from_details("2000-01-06 12:00", "Seattle, WA")
    .with_house_systems([PlacidusHouses(), WholeSignHouses()])  # Multiple systems!
    .with_sidereal("lahiri")                                    # Sidereal zodiac option
    .with_aspects(ModernAspectEngine())                         # Swap aspect engines
    .with_orbs(LuminariesOrbEngine())                          # Custom orb rules
    .add_component(ArabicPartsCalculator())                    # Plugin-style components
    .add_component(MidpointCalculator())                       # Stack as many as you want
    .calculate())                                              # Lazy evaluation

• Performance - A chart builds in ~0.2 ms, with nothing to configure or warm up
• Flexibility - Calculate multiple house systems simultaneously
• Accuracy - Swiss Ephemeris positions, cross-checked against NASA JPL Horizons (every asteroid verified to within 2 arcseconds)
• Portable output - SVG, PDF and PNG that render identically everywhere: every font and glyph the charts need ships inside the package
• Modern Python - Takes full advantage of Python 3.11+ features

Installation

pip install stellium

Requirements

• Python 3.11 or higher
• All dependencies installed automatically (pyswisseph, pytz, geopy, rich, svgwrite)
• Note: On Python 3.12+, installing requires a C toolchain (until pyswisseph ships newer wheels)

Optional Dependencies

# For data analysis with pandas DataFrames
pip install stellium[analysis]

Quick Start

Your First Chart (2 Lines of Code)

from stellium import ChartBuilder

chart = ChartBuilder.from_notable("Albert Einstein").with_aspects().calculate()
chart.draw("einstein.svg").save()

That's it! You now have a beautiful natal chart SVG for Einstein.

The from_notable() factory method uses our curated database of famous births. Other notables include: "Carl Jung", "Frida Kahlo", "Marie Curie", and more. Check out the current list.

Beautiful Visualizations, Zero Config

Want to customize your chart? The fluent .draw() API makes it effortless:

# Apply a preset for instant results
chart.draw("detailed.svg").preset_detailed().save()

# Choose a theme
chart.draw("midnight.svg").with_theme("midnight").save()

# Full customization
chart.draw("custom.svg") \
    .with_theme("celestial") \
    .with_zodiac_palette("rainbow_celestial") \
    .with_moon_phase(position="bottom-left", show_label=True) \
    .with_chart_info(position="top-left") \
    .save()

Discover features through autocomplete! Type chart.draw(). and your IDE will show you everything available.

PNG export, without the tofu

chart.draw("einstein.svg").preset_standard().save_png(scale=2)   # -> einstein.png

Rasterising an astrology SVG usually gives you a wall of tofu boxes, because general rasterisers (rsvg, cairosvg, Inkscape) resolve ♈ ♉ ♊ against the host's fonts — and most machines have no symbol font. Stellium doesn't ask the host: it bundles every font and glyph its charts need and renders with system fonts switched off, so the PNG is identical on your laptop, in CI, and in a bare container.

scale is pixels per SVG unit; the background is transparent by default. Dial charts export too.

📚 See the Visualization Guide for complete documentation, theme gallery, and examples.

Your Own Chart

from stellium import ChartBuilder

# Quick method: just pass datetime string and location
chart = ChartBuilder.from_details(
    "2000-01-06 12:00",  # ISO format, US format, or European format
    "Seattle, WA"        # City name or (lat, lon) tuple
).with_aspects().calculate()

# Access planetary positions
sun = chart.get_object("Sun")
print(sun)

moon = chart.get_object("Moon")
print(moon)
print(moon.phase)

Sun: 15°48' Capricorn (285.81°)
Moon: 16°36' Capricorn (286.61°)
Phase: New (0.0% illuminated)

Sun: 0°0' Libra (180°)
Moon: 0°0' Aries (0°)
Phase: Full (100% illuminated)

Key Features:

• Flexible datetime parsing: ISO 8601, US format, European format, or date-only
• Automatic geocoding: City name → coordinates
• Automatic timezone handling: Naive datetimes converted to UTC
• Smart defaults: Placidus houses, major (Ptolemaic) aspects, tropical zodiac

Progressive Examples

Level 1: Exploring Chart Data

from stellium import ChartBuilder

# Modern convenience method - accepts datetime strings!
chart = ChartBuilder.from_details("2000-01-06 12:00", "Seattle, WA").with_aspects().calculate()

# Get all planets
for planet in chart.get_planets():
    print(f"{planet.name}: {planet.longitude:.2f}° {planet.sign}")

# Get aspects
for aspect in chart.aspects:
    print(f"{aspect.object1.name} {aspect.aspect_name} {aspect.object2.name} (orb: {aspect.orb:.2f}°)")

# Get house cusps
houses = chart.get_houses()  # Returns HouseCusps for default (or first) system
for i, cusp in enumerate(houses.cusps, 1):
    print(f"House {i}: {cusp:.2f}°")

Sun: 285.81° Capricorn
Moon: 286.61° Capricorn
Mercury: 280.27° Capricorn
Venus: 248.03° Sagittarius
Mars: 332.10° Pisces
Jupiter: 25.52° Aries
Saturn: 40.32° Taurus
Uranus: 315.08° Aquarius
Neptune: 303.39° Aquarius
Pluto: 251.64° Sagittarius
Sun Conjunction Moon (orb: 0.80°)
Sun Conjunction Mercury (orb: 5.54°)
Sun Trine Saturn (orb: 5.49°)
Sun Conjunction MC (orb: 3.49°)
Sun Square Vertex (orb: 5.36°)
Moon Conjunction Mercury (orb: 6.34°)
Moon Trine Saturn (orb: 6.30°)
Moon Conjunction MC (orb: 4.30°)
Moon Square Vertex (orb: 6.17°)
Mercury Trine Saturn (orb: 0.05°)
Mercury Conjunction MC (orb: 2.05°)
Mercury Square Vertex (orb: 0.18°)
Venus Square Mars (orb: 5.93°)
Venus Sextile Neptune (orb: 4.64°)
Venus Conjunction Pluto (orb: 3.61°)
Venus Trine True Node (orb: 4.36°)
Venus Conjunction Chiron (orb: 4.19°)
Venus Sextile South Node (orb: 4.36°)
Venus Sextile Vertex (orb: 2.42°)
Mars Sextile ASC (orb: 5.23°)
Jupiter Square Neptune (orb: 7.87°)
Jupiter Trine Mean Apogee (orb: 1.46°)
Jupiter Conjunction ASC (orb: 1.35°)
Saturn Square Uranus (orb: 4.77°)
Saturn Square Neptune (orb: 6.93°)
Saturn Square True Node (orb: 6.65°)
Saturn Square South Node (orb: 6.65°)
Saturn Trine MC (orb: 2.00°)
Uranus Sextile Pluto (orb: 3.45°)
Uranus Sextile Chiron (orb: 2.87°)
Uranus Trine Vertex (orb: 4.64°)
Neptune Opposition True Node (orb: 0.28°)
Neptune Conjunction South Node (orb: 0.28°)
Neptune Square ASC (orb: 6.52°)
Neptune Trine Vertex (orb: 7.06°)
Pluto Trine True Node (orb: 7.97°)
Pluto Conjunction Chiron (orb: 0.58°)
Pluto Sextile Vertex (orb: 1.19°)
True Node Square ASC (orb: 6.80°)
Chiron Sextile Vertex (orb: 1.77°)
Mean Apogee Trine ASC (orb: 2.81°)
South Node Square ASC (orb: 6.80°)
South Node Trine Vertex (orb: 6.78°)
MC Square Vertex (orb: 1.87°)
House 1: 26.87°
House 2: 61.59°
House 3: 83.34°
House 4: 102.31°
House 5: 123.53°
House 6: 154.05°
House 7: 206.87°
House 8: 241.59°
House 9: 263.34°
House 10: 282.31°
House 11: 303.53°
House 12: 334.05°

Level 2: Custom House Systems & Aspects

from stellium import ChartBuilder
from stellium.engines import WholeSignHouses, ModernAspectEngine, SimpleOrbEngine

chart = (ChartBuilder.from_details("2000-01-06 12:00", "Seattle, WA")
    .with_house_systems([WholeSignHouses()])  # Use Whole Sign houses
    .with_aspects(ModernAspectEngine())       # Explicit aspect engine
    .with_orbs(SimpleOrbEngine())             # Simple orb rules
    .calculate())

print(f"House System: {chart.default_house_system}")

# Access house cusps for the specific system
whole_sign_cusps = chart.get_houses("Whole Sign")
print(whole_sign_cusps.get_description(1))  # First House

House System: Whole Sign
House 1: 0°00' Aries (0.00°)

Available House Systems: Placidus (default), Whole Sign, Koch, Equal, Regiomontanus, Campanus, Porphyry, Alcabitius, Equal (MC), Vehlow Equal, Topocentric, Morinus, and 11+ more.

Level 3: Multiple House Systems

from stellium import ChartBuilder
from stellium.engines import PlacidusHouses, WholeSignHouses, KochHouses

chart = (ChartBuilder.from_details("2000-01-06 12:00", "Seattle, WA")
    .with_house_systems([
        PlacidusHouses(),
        WholeSignHouses(),
        KochHouses()
    ])
    .calculate())

# Access each system independently
print(f"Sun in Placidus House: {chart.get_house('Sun', 'Placidus')}")

# House placements are tracked per-system
print(f"Sun in Whole Sign House: {chart.get_house('Sun', 'Whole Sign')}")

print(f"Sun in Koch House: {chart.get_house('Sun', 'Koch')}")

Sun in Placidus House: 10
Sun in Whole Sign House: 10
Sun in Koch House: 10

Level 4: Arabic Parts & Components

from stellium import ChartBuilder
from stellium.components import ArabicPartsCalculator, MidpointCalculator

chart = (ChartBuilder.from_details("2000-01-06 12:00", "Seattle, WA")
    .add_component(ArabicPartsCalculator())
    .add_component(MidpointCalculator())
    .calculate())

# Arabic Parts (automatically sect-aware)
arabic_parts = chart.get_component_result("Arabic Parts")
for part in arabic_parts:
    print(f"{part.name:25} {part.longitude:6.2f}° {part.sign:12} House {chart.get_house(part.name)}")

# Midpoints
midpoints = chart.get_component_result("Midpoints")
for mp in midpoints[:5]:  # First 5 midpoints
    print(f"{mp.object1.name}/{mp.object2.name} midpoint: {mp.longitude:.2f}°")

Part of Fortune            27.67° Aries        House 1
Part of Spirit             26.06° Aries        House 12
Part of Eros (Love)       248.83° Sagittarius  House 8
Part of Eros (Planetary)  349.09° Pisces       House 12
Part of Necessity (Ananke) 279.47° Capricorn    House 9
Part of Courage (Tolma)   331.30° Pisces       House 11
Part of Victory (Nike)     24.71° Aries        House 12
Part of Nemesis            39.51° Taurus       House 1
Part of Father            272.36° Capricorn    House 9
Part of Mother             65.45° Gemini       House 2
Part of Marriage          234.58° Scorpio      House 7
Part of Children           12.07° Aries        House 12
Part of Siblings          266.82° Sagittarius  House 9
Part of Action (Praxis)    73.16° Gemini       House 2
Part of Profession (User)  23.37° Aries        House 12
Part of Passion / Lust    302.80° Aquarius     House 10
Part of Illness / Disease 318.65° Aquarius     House 11
Part of Death             140.57° Leo          House 5
Part of Debt / Bondage    266.82° Sagittarius  House 9
Part of Travel             78.70° Gemini       House 2
Part of Friends / Associates  20.52° Aries        House 12
Part of the Sun (Exaltation) 340.57° Pisces       House 12
Part of the Moon (Exaltation)  65.45° Gemini       House 2
Part of Mercury (Exaltation)  26.87° Aries        House 1
Part of Venus (Exaltation) 249.38° Sagittarius  House 8
Part of Mars (Exaltation) 318.65° Aquarius     House 11
Part of Jupiter (Exaltation) 125.77° Leo          House 5
Part of Saturn (Exaltation) 179.15° Virgo        House 6
Sun/Moon midpoint: 286.21°
Sun/ASC midpoint: 336.34°
Sun/MC midpoint: 284.06°
Moon/ASC midpoint: 336.74°
Moon/MC midpoint: 284.46°

Available Components:

• ArabicPartsCalculator - 25+ traditional lots (Part of Fortune, Spirit, Love, etc.)
• MidpointCalculator - Direct midpoints for all planet pairs
• DignityComponent - Essential dignities (rulership, exaltation, triplicity, etc.)
• AspectPatternAnalyzer - Detect Grand Trines, T-Squares, Yods, Stelliums, etc.

Level 5: Terminal Reports with Rich

from stellium import ChartBuilder, Native, ReportBuilder
from stellium.components import DignityComponent
from stellium.engines.patterns import AspectPatternAnalyzer
from datetime import datetime

native = Native(datetime(2000, 1, 6, 12, 00), "Seattle, WA")
chart = (ChartBuilder.from_native(native)
    .with_aspects()
    .add_component(DignityComponent())
    .add_analyzer(AspectPatternAnalyzer())
    .calculate())

# Build a comprehensive terminal report
report = (ReportBuilder()
    .from_chart(chart)
    .with_chart_overview()                    # Chart metadata (date, location, zodiac system)
    .with_planet_positions(house_systems="all")  # Positions with ALL house systems
    .with_declinations()                      # Declination table with OOB detection
    .with_house_cusps(systems="all")          # House cusps for all systems
    .with_aspects(mode="major")               # Major aspects table
    .with_aspect_patterns()                   # Grand Trines, T-Squares, Yods, etc.
    .with_dignities(essential="both"))        # Essential dignities (traditional + modern)

report.render(format="rich_table")  # Beautiful terminal output

# Export to file
report.render(format="plain_table", file="my_chart.txt")
report.render(format="pdf", file="my_chart.pdf")  # PDF with Typst

Chart Overview
──────────────
Date: January 06, 2000
Time: 12:00 PM
Timezone: America/Los_Angeles
Location: Seattle, King County, Washington, United States
Coordinates: 47.6038°, -122.3301°
House System: Placidus
Zodiac: Tropical
Chart Sect: Day Chart
Chart Ruler: Mars (Aries Rising)

Planet Positions
────────────────
┏━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━┓
┃ Planet              ┃ Position              ┃ House (Pl) ┃
┡━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━┩
│ ☉ Sun               │ ♑︎ Capricorn 15°48'   │ 10         │
│ ☽ Moon              │ ♑︎ Capricorn 16°36'   │ 10         │
│ ☿ Mercury           │ ♑︎ Capricorn 10°16'   │ 9          │
│ ♀ Venus             │ ♐︎ Sagittarius 8°01'  │ 8          │
│ ♂ Mars              │ ♓︎ Pisces 2°06'       │ 11         │
│ ♃ Jupiter           │ ♈︎ Aries 25°31'       │ 12         │
│ ♄ Saturn            │ ♉︎ Taurus 10°18'      │ 1          │
│ ♅ Uranus            │ ♒︎ Aquarius 15°05'    │ 11         │
│ ♆ Neptune           │ ♒︎ Aquarius 3°23'     │ 10         │
│ ♇ Pluto             │ ♐︎ Sagittarius 11°38' │ 8          │
│ ☊ North Node        │ ♌︎ Leo 3°40'          │ 5          │
│ ☋ South Node        │ ♒︎ Aquarius 3°40'     │ 11         │
│ ⚸ Black Moon Lilith │ ♐︎ Sagittarius 24°03' │ 9          │
│ 🜊 Vertex            │ ♎︎ Libra 10°26'       │ 6          │
│ ⚷ Chiron            │ ♐︎ Sagittarius 12°13' │ 8          │
└─────────────────────┴───────────────────────┴────────────┘

Declinations
────────────
┏━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━┓
┃ Planet       ┃ Declination ┃ Direction ┃ Status ┃
┡━━━━━━━━━━━━━━╇━━━━━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━┩
│ ☉ Sun        │ 22°30'      │ South     │        │
│ ☽ Moon       │ 20°52'      │ South     │        │
│ ☿ Mercury    │ 24°30'      │ South     │ OOB ⚠  │
│ ♀ Venus      │ 19°46'      │ South     │        │
│ ♂ Mars       │ 11°39'      │ South     │        │
│ ♃ Jupiter    │ 8°42'       │ North     │        │
│ ♄ Saturn     │ 12°36'      │ North     │        │
│ ♅ Uranus     │ 16°56'      │ South     │        │
│ ♆ Neptune    │ 19°10'      │ South     │        │
│ ♇ Pluto      │ 11°24'      │ South     │        │
│ ☊ North Node │ 19°19'      │ North     │        │
└──────────────┴─────────────┴───────────┴────────┘

House Cusps
───────────
┏━━━━━━━┳━━━━━━━━━━━━┓
┃ House ┃ Cusp (Pl)  ┃
┡━━━━━━━╇━━━━━━━━━━━━┩
│ 1     │ 26° ♈︎ 51' │
│ 2     │ 1° ♊︎ 35'  │
│ 3     │ 23° ♊︎ 20' │
│ 4     │ 12° ♋︎ 18' │
│ 5     │ 3° ♌︎ 31'  │
│ 6     │ 4° ♍︎ 03'  │
│ 7     │ 26° ♎︎ 51' │
│ 8     │ 1° ♐︎ 35'  │
│ 9     │ 23° ♐︎ 20' │
│ 10    │ 12° ♑︎ 18' │
│ 11    │ 3° ♒︎ 31'  │
│ 12    │ 4° ♓︎ 03'  │
└───────┴────────────┘

Major Aspects
─────────────

  Aspectarian
[SVG: 404x404px - use HTML/PDF output to view]

  Aspect List
┏━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━┳━━━━━━━━━━┓
┃ Planet 1            ┃ Aspect        ┃ Planet 2            ┃ Orb   ┃ Applying ┃
┡━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━╇━━━━━━━━━━┩
│ ☿ Mercury           │ △ Trine       │ ♄ Saturn            │ 0.05° │ A→       │
│ ☿ Mercury           │ □ Square      │ 🜊 Vertex            │ 0.18° │ —        │
│ ♆ Neptune           │ ☌ Conjunction │ ☋ South Node        │ 0.28° │ A→       │
│ ♆ Neptune           │ ☍ Opposition  │ ☊ North Node        │ 0.28° │ A→       │
│ ♇ Pluto             │ ☌ Conjunction │ ⚷ Chiron            │ 0.58° │ ←S       │
│ ☉ Sun               │ ☌ Conjunction │ ☽ Moon              │ 0.80° │ ←S       │
│ ♇ Pluto             │ ⚹ Sextile     │ 🜊 Vertex            │ 1.19° │ —        │
│ ♃ Jupiter           │ ☌ Conjunction │ ASC                 │ 1.35° │ —        │
│ ♃ Jupiter           │ △ Trine       │ ⚸ Black Moon Lilith │ 1.46° │ A→       │
│ ⚷ Chiron            │ ⚹ Sextile     │ 🜊 Vertex            │ 1.77° │ —        │
│ MC                  │ □ Square      │ 🜊 Vertex            │ 1.87° │ —        │
│ ♄ Saturn            │ △ Trine       │ MC                  │ 2.00° │ —        │
│ ☿ Mercury           │ ☌ Conjunction │ MC                  │ 2.05° │ —        │
│ ♀ Venus             │ ⚹ Sextile     │ 🜊 Vertex            │ 2.42° │ —        │
│ ⚸ Black Moon Lilith │ △ Trine       │ ASC                 │ 2.81° │ —        │
│ ♅ Uranus            │ ⚹ Sextile     │ ⚷ Chiron            │ 2.87° │ A→       │
│ ♅ Uranus            │ ⚹ Sextile     │ ♇ Pluto             │ 3.45° │ ←S       │
│ ☉ Sun               │ ☌ Conjunction │ MC                  │ 3.49° │ —        │
│ ♀ Venus             │ ☌ Conjunction │ ♇ Pluto             │ 3.61° │ A→       │
│ ♀ Venus             │ ☌ Conjunction │ ⚷ Chiron            │ 4.19° │ A→       │
│ ☽ Moon              │ ☌ Conjunction │ MC                  │ 4.30° │ —        │
│ ♀ Venus             │ ⚹ Sextile     │ ☋ South Node        │ 4.36° │ ←S       │
│ ♀ Venus             │ △ Trine       │ ☊ North Node        │ 4.36° │ ←S       │
│ ♅ Uranus            │ △ Trine       │ 🜊 Vertex            │ 4.64° │ —        │
│ ♀ Venus             │ ⚹ Sextile     │ ♆ Neptune           │ 4.64° │ ←S       │
│ ♄ Saturn            │ □ Square      │ ♅ Uranus            │ 4.77° │ ←S       │
│ ♂ Mars              │ ⚹ Sextile     │ ASC                 │ 5.23° │ —        │
│ ☉ Sun               │ □ Square      │ 🜊 Vertex            │ 5.36° │ —        │
│ ☉ Sun               │ △ Trine       │ ♄ Saturn            │ 5.49° │ ←S       │
│ ☉ Sun               │ ☌ Conjunction │ ☿ Mercury           │ 5.54° │ A→       │
│ ♀ Venus             │ □ Square      │ ♂ Mars              │ 5.93° │ ←S       │
│ ☽ Moon              │ □ Square      │ 🜊 Vertex            │ 6.17° │ —        │
│ ☽ Moon              │ △ Trine       │ ♄ Saturn            │ 6.30° │ ←S       │
│ ☽ Moon              │ ☌ Conjunction │ ☿ Mercury           │ 6.34° │ ←S       │
│ ♆ Neptune           │ □ Square      │ ASC                 │ 6.52° │ —        │
│ ♄ Saturn            │ □ Square      │ ☋ South Node        │ 6.65° │ A→       │
│ ♄ Saturn            │ □ Square      │ ☊ North Node        │ 6.65° │ ←S       │
│ ☋ South Node        │ △ Trine       │ 🜊 Vertex            │ 6.78° │ —        │
│ ☋ South Node        │ □ Square      │ ASC                 │ 6.80° │ —        │
│ ☊ North Node        │ □ Square      │ ASC                 │ 6.80° │ —        │
│ ♄ Saturn            │ □ Square      │ ♆ Neptune           │ 6.93° │ A→       │
│ ♆ Neptune           │ △ Trine       │ 🜊 Vertex            │ 7.06° │ —        │
│ ♃ Jupiter           │ □ Square      │ ♆ Neptune           │ 7.87° │ A→       │
│ ♇ Pluto             │ △ Trine       │ ☊ North Node        │ 7.97° │ ←S       │
└─────────────────────┴───────────────┴─────────────────────┴───────┴──────────┘

Aspect Patterns
───────────────
┏━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Pattern  ┃ Planets                           ┃ Element/Quality  ┃ Details                   ┃
┡━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ Stellium │ ☉ Sun, ☽ Moon, ☿ Mercury, MC      │ Earth / Cardinal │ 4 planets                 │
│ T-Square │ ♆ Neptune, ☊ North Node, ♄ Saturn │ Fixed            │ 3 planets, Apex: ♄ Saturn │
│ T-Square │ ♆ Neptune, ☊ North Node, ASC      │ Mixed            │ 3 planets, Apex: ASC      │
└──────────┴───────────────────────────────────┴──────────────────┴───────────────────────────┘

Essential Dignities
───────────────────
┏━━━━━━━━━━━┳━━━━━━━━━━━━┳━━━━━━━━━━━┓
┃ Planet    ┃ Trad Score ┃ Mod Score ┃
┡━━━━━━━━━━━╇━━━━━━━━━━━━╇━━━━━━━━━━━┩
│ ☉ Sun     │ 0          │ 0         │
│ ☽ Moon    │ -5         │ -5        │
│ ☿ Mercury │ 0          │ 0         │
│ ♀ Venus   │ 0          │ 0         │
│ ♂ Mars    │ 0          │ 0         │
│ ♃ Jupiter │ 0          │ 0         │
│ ♄ Saturn  │ 0          │ 0         │
│ ♅ Uranus  │ 0          │ +6        │
│ ♆ Neptune │ 0          │ -4        │
│ ♇ Pluto   │ 0          │ 0         │
│ ⚷ Chiron  │ 0          │ 0         │
└───────────┴────────────┴───────────┘

Chart Overview
==============
        Date: January 06, 2000
        Time: 12:00 PM
    Timezone: America/Los_Angeles
    Location: Seattle, King County, Washington, United States
 Coordinates: 47.6038°, -122.3301°
House System: Placidus
      Zodiac: Tropical
  Chart Sect: Day Chart
 Chart Ruler: Mars (Aries Rising)


Planet Positions
================
| Planet              | Position              | House (Pl) |
|---------------------|-----------------------|------------|
| ☉ Sun               | ♑︎ Capricorn 15°48'   | 10         |
| ☽ Moon              | ♑︎ Capricorn 16°36'   | 10         |
| ☿ Mercury           | ♑︎ Capricorn 10°16'   | 9          |
| ♀ Venus             | ♐︎ Sagittarius 8°01'  | 8          |
| ♂ Mars              | ♓︎ Pisces 2°06'       | 11         |
| ♃ Jupiter           | ♈︎ Aries 25°31'       | 12         |
| ♄ Saturn            | ♉︎ Taurus 10°18'      | 1          |
| ♅ Uranus            | ♒︎ Aquarius 15°05'    | 11         |
| ♆ Neptune           | ♒︎ Aquarius 3°23'     | 10         |
| ♇ Pluto             | ♐︎ Sagittarius 11°38' | 8          |
| ☊ North Node        | ♌︎ Leo 3°40'          | 5          |
| ☋ South Node        | ♒︎ Aquarius 3°40'     | 11         |
| ⚸ Black Moon Lilith | ♐︎ Sagittarius 24°03' | 9          |
| 🜊 Vertex            | ♎︎ Libra 10°26'       | 6          |
| ⚷ Chiron            | ♐︎ Sagittarius 12°13' | 8          |


Declinations
============
| Planet       | Declination | Direction | Status |
|--------------|-------------|-----------|--------|
| ☉ Sun        | 22°30'      | South     |        |
| ☽ Moon       | 20°52'      | South     |        |
| ☿ Mercury    | 24°30'      | South     | OOB ⚠  |
| ♀ Venus      | 19°46'      | South     |        |
| ♂ Mars       | 11°39'      | South     |        |
| ♃ Jupiter    | 8°42'       | North     |        |
| ♄ Saturn     | 12°36'      | North     |        |
| ♅ Uranus     | 16°56'      | South     |        |
| ♆ Neptune    | 19°10'      | South     |        |
| ♇ Pluto      | 11°24'      | South     |        |
| ☊ North Node | 19°19'      | North     |        |


House Cusps
===========
| House | Cusp (Pl)  |
|-------|------------|
| 1     | 26° ♈︎ 51' |
| 2     | 1° ♊︎ 35'  |
| 3     | 23° ♊︎ 20' |
| 4     | 12° ♋︎ 18' |
| 5     | 3° ♌︎ 31'  |
| 6     | 4° ♍︎ 03'  |
| 7     | 26° ♎︎ 51' |
| 8     | 1° ♐︎ 35'  |
| 9     | 23° ♐︎ 20' |
| 10    | 12° ♑︎ 18' |
| 11    | 3° ♒︎ 31'  |
| 12    | 4° ♓︎ 03'  |


Major Aspects
=============

  Aspectarian
  -----------
  (unknown type svg)

  Aspect List
  -----------
| Planet 1            | Aspect        | Planet 2            | Orb   | Applying |
|---------------------|---------------|---------------------|-------|----------|
| ☿ Mercury           | △ Trine       | ♄ Saturn            | 0.05° | A→       |
| ☿ Mercury           | □ Square      | 🜊 Vertex            | 0.18° | —        |
| ♆ Neptune           | ☌ Conjunction | ☋ South Node        | 0.28° | A→       |
| ♆ Neptune           | ☍ Opposition  | ☊ North Node        | 0.28° | A→       |
| ♇ Pluto             | ☌ Conjunction | ⚷ Chiron            | 0.58° | ←S       |
| ☉ Sun               | ☌ Conjunction | ☽ Moon              | 0.80° | ←S       |
| ♇ Pluto             | ⚹ Sextile     | 🜊 Vertex            | 1.19° | —        |
| ♃ Jupiter           | ☌ Conjunction | ASC                 | 1.35° | —        |
| ♃ Jupiter           | △ Trine       | ⚸ Black Moon Lilith | 1.46° | A→       |
| ⚷ Chiron            | ⚹ Sextile     | 🜊 Vertex            | 1.77° | —        |
| MC                  | □ Square      | 🜊 Vertex            | 1.87° | —        |
| ♄ Saturn            | △ Trine       | MC                  | 2.00° | —        |
| ☿ Mercury           | ☌ Conjunction | MC                  | 2.05° | —        |
| ♀ Venus             | ⚹ Sextile     | 🜊 Vertex            | 2.42° | —        |
| ⚸ Black Moon Lilith | △ Trine       | ASC                 | 2.81° | —        |
| ♅ Uranus            | ⚹ Sextile     | ⚷ Chiron            | 2.87° | A→       |
| ♅ Uranus            | ⚹ Sextile     | ♇ Pluto             | 3.45° | ←S       |
| ☉ Sun               | ☌ Conjunction | MC                  | 3.49° | —        |
| ♀ Venus             | ☌ Conjunction | ♇ Pluto             | 3.61° | A→       |
| ♀ Venus             | ☌ Conjunction | ⚷ Chiron            | 4.19° | A→       |
| ☽ Moon              | ☌ Conjunction | MC                  | 4.30° | —        |
| ♀ Venus             | ⚹ Sextile     | ☋ South Node        | 4.36° | ←S       |
| ♀ Venus             | △ Trine       | ☊ North Node        | 4.36° | ←S       |
| ♅ Uranus            | △ Trine       | 🜊 Vertex            | 4.64° | —        |
| ♀ Venus             | ⚹ Sextile     | ♆ Neptune           | 4.64° | ←S       |
| ♄ Saturn            | □ Square      | ♅ Uranus            | 4.77° | ←S       |
| ♂ Mars              | ⚹ Sextile     | ASC                 | 5.23° | —        |
| ☉ Sun               | □ Square      | 🜊 Vertex            | 5.36° | —        |
| ☉ Sun               | △ Trine       | ♄ Saturn            | 5.49° | ←S       |
| ☉ Sun               | ☌ Conjunction | ☿ Mercury           | 5.54° | A→       |
| ♀ Venus             | □ Square      | ♂ Mars              | 5.93° | ←S       |
| ☽ Moon              | □ Square      | 🜊 Vertex            | 6.17° | —        |
| ☽ Moon              | △ Trine       | ♄ Saturn            | 6.30° | ←S       |
| ☽ Moon              | ☌ Conjunction | ☿ Mercury           | 6.34° | ←S       |
| ♆ Neptune           | □ Square      | ASC                 | 6.52° | —        |
| ♄ Saturn            | □ Square      | ☋ South Node        | 6.65° | A→       |
| ♄ Saturn            | □ Square      | ☊ North Node        | 6.65° | ←S       |
| ☋ South Node        | △ Trine       | 🜊 Vertex            | 6.78° | —        |
| ☋ South Node        | □ Square      | ASC                 | 6.80° | —        |
| ☊ North Node        | □ Square      | ASC                 | 6.80° | —        |
| ♄ Saturn            | □ Square      | ♆ Neptune           | 6.93° | A→       |
| ♆ Neptune           | △ Trine       | 🜊 Vertex            | 7.06° | —        |
| ♃ Jupiter           | □ Square      | ♆ Neptune           | 7.87° | A→       |
| ♇ Pluto             | △ Trine       | ☊ North Node        | 7.97° | ←S       |


Aspect Patterns
===============
| Pattern  | Planets                           | Element/Quality  | Details                   |
|----------|-----------------------------------|------------------|---------------------------|
| Stellium | ☉ Sun, ☽ Moon, ☿ Mercury, MC      | Earth / Cardinal | 4 planets                 |
| T-Square | ♆ Neptune, ☊ North Node, ♄ Saturn | Fixed            | 3 planets, Apex: ♄ Saturn |
| T-Square | ♆ Neptune, ☊ North Node, ASC      | Mixed            | 3 planets, Apex: ASC      |


Essential Dignities
===================
| Planet    | Trad Score | Mod Score |
|-----------|------------|-----------|
| ☉ Sun     | 0          | 0         |
| ☽ Moon    | -5         | -5        |
| ☿ Mercury | 0          | 0         |
| ♀ Venus   | 0          | 0         |
| ♂ Mars    | 0          | 0         |
| ♃ Jupiter | 0          | 0         |
| ♄ Saturn  | 0          | 0         |
| ♅ Uranus  | 0          | +6        |
| ♆ Neptune | 0          | -4        |
| ♇ Pluto   | 0          | 0         |
| ⚷ Chiron  | 0          | 0         |

Level 6: Advanced - Bi-Wheel Charts

from stellium import MultiChartBuilder

# Synastry chart (relationship analysis)
synastry = MultiChartBuilder.synastry(
    ("1994-01-06 11:47", "Palo Alto, CA"),
    ("1995-06-15 14:30", "Seattle, WA"),
    label1="Kate",
    label2="Alex",
).calculate()

# Draw bi-wheel with both charts
synastry.draw("synastry_biwheel.svg") \
    .preset_detailed() \
    .save()

# Access inner and outer charts separately
inner_chart = synastry.inner
outer_chart = synastry.outer

# Get cross-chart aspects
cross_aspects = synastry.get_cross_aspects()
for aspect in cross_aspects[:10]:
    print(f"{aspect.object1.name} ({synastry.labels[0]}) "
          f"{aspect.aspect_name} "
          f"{aspect.object2.name} ({synastry.labels[1]})")

Sun (Kate) Trine Mars (Alex)
Sun (Kate) Trine Chiron (Alex)
Sun (Kate) Opposition MC (Alex)
Sun (Kate) Conjunction IC (Alex)
Moon (Kate) Sextile Mars (Alex)
Moon (Kate) Conjunction True Node (Alex)
Moon (Kate) Opposition South Node (Alex)
Moon (Kate) Trine MC (Alex)
Moon (Kate) Sextile IC (Alex)
Mercury (Kate) Trine Chiron (Alex)

Comparison Chart Types:

• Synastry: Relationship compatibility and dynamics
• Transit: Current planetary influences on natal chart
• Progression: Secondary progressions for timing
• Composite: Relationship midpoint chart (synthesis)
• Davison: Relationship chart with actual location

Command-Line Interface

Stellium includes a CLI for quick chart generation:

# Generate a chart from the notable database
stellium chart notable "Albert Einstein" --output einstein.svg

# Manage ephemeris data
stellium ephemeris download --years 1000-3000

# Clear calculation cache
stellium cache clear

See stellium --help for full CLI documentation.

Where Stellium Reads and Writes

Stellium touches exactly two directories, and they get opposite treatment:

Enough Swiss Ephemeris data to cover 1800–2999 CE is bundled and unpacked on first use, so most users never need to download anything. To see where both directories actually resolved — and whether a variable or the default put them there — run stellium cache info.

📍 docs/LOCATIONS.md — custom ephemeris folders, portable and read-only-$HOME installs (Docker, Lambda, Windows embedded Python on a D: drive), what is safe to delete, and troubleshooting.

Feature Highlights

Zodiac Systems

• Tropical Zodiac (Western astrology) - default
• Sidereal Zodiac (Vedic/Hindu astrology) with 9 ayanamsa systems:
  • Lahiri (default for sidereal)
  • Fagan-Bradley
  • Raman
  • Krishnamurti
  • Yukteshwar
  • J.N. Bhasin
  • True Chitrapaksha
  • True Revati
  • De Luce

# Tropical (default)
chart = ChartBuilder.from_native(native).calculate()

# Sidereal with Lahiri ayanamsa
chart = ChartBuilder.from_native(native).with_sidereal("lahiri").calculate()

# Sidereal with custom ayanamsa
chart = ChartBuilder.from_native(native).with_sidereal("fagan_bradley").calculate()

Celestial Objects

Calculate positions for 50+ celestial objects:

• Planets: Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
• Asteroids: Chiron, Ceres, Pallas, Juno, Vesta
• Lunar Nodes: North Node, South Node, True Node, Mean Node
• Lunar Apogee: Lilith (Mean, True, Osculating, Interpolated)
• Chart Points: Ascendant, Midheaven, Descendant, IC, Vertex, East Point

Coordinate Systems

• Ecliptic Coordinates: Longitude, latitude (distance from ecliptic)
• Equatorial Coordinates: Right ascension, declination (distance from celestial equator)
• Out-of-Bounds Detection: Automatically identifies planets with extreme declinations (>23°27')

sun = chart.get_object("Sun")
print(f"Ecliptic: {sun.longitude:.2f}° longitude, {sun.latitude:.2f}° latitude")
print(f"Equatorial: {sun.right_ascension:.2f}° RA, {sun.declination:.2f}° declination")
if sun.is_out_of_bounds:
    print(f"⚠ Sun is out of bounds!")

Aspect Calculations

• Major Aspects (Ptolemaic): Conjunction (0°), Opposition (180°), Square (90°), Trine (120°), Sextile (60°)
• Minor Aspects: Semi-sextile (30°), Semi-square (45°), Sesquiquadrate (135°), Quincunx (150°)
• Harmonic Aspects: Quintile (72°), Bi-quintile (144°), Septile (51.43°), Novile (40°), and more
• Configurable Orbs: Simple, Luminaries-specific, or Complex (aspect-and-planet-pair-specific) orb engines

Dignities

• Essential Dignities: Ruler, Exaltation, Triplicity (by sect), Bound, Decan, Detriment, Fall
• Accidental Dignities: House placement, angular/succedent/cadent, joy
• Both Traditional & Modern rulerships supported

Comparison Charts (Bi-Wheels)

Create relationship, timing, and synthesis charts:

from stellium import MultiChartBuilder, Native, SynthesisBuilder

# Synastry (relationship analysis)
synastry = MultiChartBuilder.synastry(
    ("1994-01-06 11:47", "Palo Alto, CA"),
    ("1995-06-15 14:30", "Seattle, WA"),
    label1="Person A",
    label2="Person B",
).calculate()
synastry.draw("synastry.svg").save()

# Transits (timing analysis)
transits = MultiChartBuilder.transit(
    natal_data=("1994-01-06 11:47", "Palo Alto, CA"),
    transit_data=("2025-11-26 12:00", "Palo Alto, CA"),
).calculate()

# Composite (relationship midpoint chart)
native_a = Native("1994-01-06 11:47", "Palo Alto, CA")
native_b = Native("1995-06-15 14:30", "Seattle, WA")
composite = SynthesisBuilder.composite(native_a, native_b).calculate()

# Davison (relationship midpoint chart with actual location)
davison = SynthesisBuilder.davison(native_a, native_b).calculate()

Comparison Types:

• Synastry: Two natal charts overlaid (bi-wheel)
• Transit: Natal chart + current/future planets
• Progression: Natal chart + progressed positions
• Composite: Midpoint chart (mathematical average)
• Davison: Midpoint chart with actual geographic location

Unknown Birth Time Charts

Handle charts when birth time is unknown:

# Create chart with unknown time (defaults to noon, skips houses/angles)
chart = ChartBuilder.from_details(
    "1994-01-06",  # Date only
    "Palo Alto, CA",
    time_unknown=True
).calculate()

# Visualize with Moon's daily arc
chart.draw("unknown_time.svg").save()  # Shows Moon's possible range

Birth-Time Rectification (Sect)

Recover the one thing that is recoverable from an unknown birth time — sect (day vs night) — at ~70% accuracy (cross-validated). It's a single honest call, and an indicator, not an oracle: Stellium deliberately refuses to invent a minute-level time (the inverse is ill-posed). See the Rectification Guide for what it does, and — importantly — how not to use it.

from stellium import ChartBuilder, analyze_sect

chart = ChartBuilder.from_notable("Frida Kahlo").calculate()
a = analyze_sect(chart)                       # events auto-looked-up for notables
print(f"{a.p_day:.2f} → {a.leans}")           # 0.80 → day

# Or as a report section (renders in every format):
from stellium import ReportBuilder
ReportBuilder().from_chart(chart).with_sect_rectification().render(format="markdown")

0.80 → day
## Sect Rectification

### Anchor

**Chart sect (as given):** Day  
**Daylight prior P(day):** 0.55  (geometry, the base rate)  
**Calibrated P(day):** 0.80  → leans DAY (80% conf)  
**Reading:** indicator, not oracle — adjudicate with real knowledge  
**⚠ Moon band:** Moon crosses Taurus → Gemini within the 24h — its sign (and anything it rules) is a band, not a point.  

### Day vs Night hypotheses

|                     | IF DAY (above horizon)                                    | IF NIGHT (below horizon)                                     |
| ------------------- | --------------------------------------------------------- | ------------------------------------------------------------ |
| Sect light          | Sun in Cancer (peregrine)                                 | Moon in Taurus (exalted)                                     |
| Out-of-sect malefic | Mars in Capricorn (exalted)                               | Saturn in Pisces (peregrine)                                 |
|   → hardship reads  | hot, sharp, sudden — accidents, violence, fever, conflict | cold, slow, chronic — illness, poverty, confinement, decline |
| In-sect benefic     | Jupiter in Cancer (exalted)                               | Venus in Gemini (peregrine)                                  |
|   → fortune reads   | Jupiter-toned — honour, wealth, law, faith, expansion     | Venus-toned — love, art, beauty, pleasure, music             |

### Evidence & convergence

Evidence alignment — does the life match each hypothesis?
  hardship flavour (malefic-of-sect, VALIDATED +0.35): leans DAY  (4.0 day / 2.0 night)
  fortune flavour  (benefic-of-sect): leans NIGHT  (0.6 day / 7.6 night)
  firdaria time-lord fit: day-hits 9 / night-hits 8 → favours day

Soft signals (⚠ ~null on strangers — high value only with real first-hand knowledge):
  malefic-of-temperament (Mars-hot − Saturn-cold) = +0 → —
  sect-light temperament (Solar − Lunar)        = +1 → DAY

Convergence (counted, never summed): DAY 3 · NIGHT 1 (of 4 techniques)
→ SECT: trust this anchor — it is the only cross-validated signal (~70%). The soft/timing rows routinely point the wrong way; when they fight the anchor on sect, the anchor wins. TIME-within-sect is where your own knowledge decides.

Data Export

# Export to dictionary for JSON serialization
data = chart.to_dict()

# Includes:
# - All planetary positions with coordinates
# - House cusps for all calculated systems
# - All aspects with orbs
# - Component results (Arabic Parts, midpoints, etc.)
# - Chart metadata (date, location, timezone)

PDF Planner Generation

Generate a personalized year-long astrological planner as a PDF:

from stellium import Native, PlannerBuilder

native = Native("1990-05-15 14:30", "San Francisco, CA")

planner = (
    PlannerBuilder.for_native(native)
    .year(2026)
    .timezone("America/Los_Angeles")
    .theme("house")          # or sepia / celestial / blues / greyscale
    .page_size("letter")
    .generate("my_planner.pdf")
)

The front matter is curated on by default, so that's already a complete planner. Drop any page with the matching .without_*() call.

The reference section (front matter). A planner isn't a report — you don't read it once, you consult it all year with a pen in hand. So its front matter answers the questions the daily pages provoke:

• The Year at a Glance — Lord of the Year, the solar return, eclipses placed in your houses, every retrograde window, and the slow transits that shape the year
• A year overview — twelve mini-months with eclipse and station days marked
• Your natal chart as a lookup — the positions table leads (when a daily page says Moon □ natal Mercury, this is where you find out where natal Mercury is), with the wheel following
• The year's transit map, solar return and profections
• The progressed Moon — its dated exact aspects to your natal planets
• Zodiacal releasing, scoped to this year
• A glyph legend for reading the daily pages

The year itself. Monthly calendar grids with every event packed into the day cells, then weekly pages of day boxes with room to write.

Themed. All five design-system themes apply — chart wheels, aspect colours and table shading stay coordinated with the page. Use greyscale if you're printing at home; it swaps ink fills for outlines. Fonts are bundled, so the PDF renders identically on any machine.

Requires the typst binary.

See the planner cookbook for detailed recipes, and an example planner for the output.

Chart Atlas PDF Generation

Generate multi-page PDF documents with one chart per page, like an old-school astrologer's chart atlas:

from stellium.visualization.atlas import AtlasBuilder
from stellium.core.native import Native
from datetime import datetime

# Create an atlas from notables
(AtlasBuilder()
    .add_notable("Albert Einstein")
    .add_notable("Marie Curie")
    .add_notable("Isaac Newton")
    .with_title_page("Famous Scientists")
    .with_header()
    .with_theme("midnight")
    .save("scientists_atlas.pdf"))

# Or with Uranian dials
native1 = Native(datetime(1994, 1, 6, 11, 47), "Palo Alto, CA")
native2 = Native(datetime(1995, 6, 15, 14, 30), "Seattle, WA")
native3 = Native(datetime(2000, 3, 20, 8, 0), "Portland, OR")
(AtlasBuilder()
    .add_natives([native1, native2, native3])
    .with_chart_type("dial", degrees=90)
    .save("uranian_atlas.pdf"))

# Generate atlas from entire notables database
AtlasBuilder.from_all_notables().save("complete_atlas.pdf")

# Filter by category and sort by birth date
AtlasBuilder.from_all_notables(category="scientist", sort_by="date").save("scientists.pdf")

Atlas Features:

• Multiple input methods: Add natives directly, look up notables by name, or use from_all_notables() for the entire database
• Category filtering: Filter notables by category (scientist, artist, etc.) and sort by name or date
• Chart types: Natal wheels or Uranian dials (90°, 45°, 360°)
• Configurable: Headers, themes, page sizes (Letter, A4, half-letter)
• Title page: Optional title page for the atlas

Requires: pip install typst

Data Analysis (pandas Integration)

Batch calculate charts and analyze with pandas DataFrames:

from stellium.analysis import BatchCalculator, ChartStats, charts_to_dataframe

# Calculate 100s of charts from the notables database
charts = BatchCalculator.from_registry(category="scientist").calculate_all()

# Convert to pandas DataFrame
df = charts_to_dataframe(charts)
print(df['sun_sign'].value_counts())

# Statistical analysis
stats = ChartStats(charts)
print(stats.element_distribution())
print(stats.sign_distribution("Sun"))

sun_sign
Pisces         3
Capricorn      3
Scorpio        2
Cancer         2
Aquarius       2
Taurus         2
Sagittarius    2
Leo            2
Gemini         2
Name: count, dtype: int64
{'fire': 0.24, 'earth': 0.23, 'air': 0.215, 'water': 0.315}
{'Aries': 0, 'Taurus': 2, 'Gemini': 2, 'Cancer': 2, 'Leo': 2, 'Virgo': 0, 'Libra': 0, 'Scorpio': 2, 'Sagittarius': 2, 'Capricorn': 3, 'Aquarius': 2, 'Pisces': 3}

Requires: pip install stellium[analysis]

See the analysis cookbook for comprehensive examples.

Performance

A chart builds in about 0.2 ms. There is nothing to configure and nothing to warm up.

from stellium import ChartBuilder, Native

native = Native("2000-01-06 12:00", "Seattle, WA")
chart = ChartBuilder.from_native(native).calculate()   # ~0.2 ms

Chart calculation is not cached — recomputing is faster than reading a cache. Geocoding is cached, since that one is a network call; it lives in ~/.cache/stellium/ (see docs/LOCATIONS.md).

Documentation & Learning

Example Cookbooks

📖 Read the cookbooks on the docs site: stellium.readthedocs.io → Cookbooks

367 runnable recipes across 21 cookbooks — each rendered with its real output: the tables it prints and the charts it draws, captured by running the code when the docs are built. Same recipes as examples/, but you can see what they produce without running anything.

The examples/ directory is the source those pages are generated from — every recipe on the site is literalincluded from a real function in a real script, so the two can never disagree.

# Or run any of them yourself
python examples/chart_cookbook.py

User Guides

Visual Galleries

Lists of Implemented Options

• See the full documentation list

Quick Start

# Clone and install
git clone https://github.com/katelouie/stellium.git
cd stellium
pip install -e .

# Run example cookbooks
python examples/chart_cookbook.py      # Generate chart SVGs
python examples/report_cookbook.py     # Generate PDF reports
python examples/comparison_cookbook.py # Generate synastry charts

Roadmap

• See TODO.md for the full development roadmap.
• See CHANGELOG.md for a detailed changelog by version.

Contributing

I welcome contributions from both Python developers and astrologers! Whether you want to:

• Add new calculation engines
• Improve documentation
• Fix bugs
• Add new features
• Share examples

Please see CONTRIBUTING.md for detailed guidelines and an overview of the architecture philosophy and testing.

License

Stellium is released under the AGPLv3.0 License. See LICENSE for details. This is primarily because the core dependency pyswisseph uses AGPLv3 and the even-more-core-dependency Swiss Ephemeris has the dual licensing situation seen below.

Note on Swiss Ephemeris: This library uses the Swiss Ephemeris, which has its own licensing terms for commercial use. See the Swiss Ephemeris website for details.

Acknowledgments

• Swiss Ephemeris - Astronomical calculations of exceptional accuracy
• Astro.com - Ephemeris data and astrological resources
• PySwissEph - Python bindings for Swiss Ephemeris
• Zhanran Astrology / 湛然星座 for Chinese localization.

Community & Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions

Built with precision, designed for everyone

Whether you're building a professional astrology application, researching astrological patterns, or learning computational astrology: Stellium provides the tools you need with a modern, extensible architecture.