Western Astrology Suite

Six Charts. One Complete System.

From natal birth chart to synastry, progressions, and solar return — powered by VSOP87B and verified against NASA JPL Horizons.

☿︎ VSOP87B Engine 🛰 NASA JPL Verified ⌂ Placidus Houses
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Sub-arcsecond precision  ·  Sun–Neptune within 0.01° of NASA JPL

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All Six Chart Types

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NATAL

Natal Chart

Your complete birth chart — the foundation of Western astrology. Shows planets, houses, and aspects at the exact moment of your birth. The essential starting point.

BIG 3

The Big Three

Your Sun, Moon, and Rising signs — the three pillars of your personality in Western astrology. The fastest way to understand your core nature.

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TRANSIT

Transit Chart

Current sky planets overlaid on your natal chart. See which areas of life are activated right now and what cosmic weather you’re navigating today.

SYNASTRY

Synastry Chart

Two natal charts overlaid to reveal planetary connections between two people. See harmonies, tensions, and the energetic dynamic of any relationship.

COMPOSITE

Composite Chart

The midpoint chart of two people — a single chart representing the relationship itself. Shows the relationship’s purpose, strengths, and challenges.

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SOLAR RETURN

Solar Return Chart

A full chart cast for the exact moment the Sun returns to your natal position each year. Your personal new year chart — themes, opportunities, and focus areas for the coming 12 months.

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PROGRESSED

Progressed Chart

Secondary progressions — 1 day after birth symbolizes 1 year of life. Shows the slow inner evolution of personality and life themes over time.

Chart Comparison

Feature Natal Transit Synastry Composite Solar Return Progressed
People needed 112211
Time sensitivity BirthLiveBirth ×2Birth ×2AnnualAge-based
House system A onlyComposite
Aspects shown NatalCrossCrossCompositeSRProgressed
Tier 2 2 3 3 3 3
Best for Self Now Partners Couple Year ahead Growth

Frequently Asked Questions

Everything you need to know about Western astrology charts.

Start with the Natal Chart — it’s the foundation. Once you understand your natal chart, the others (transit, progressed, etc.) all reference it.
Synastry overlays two charts to show how planets interact between two people. Composite creates a new single chart from the midpoints — it represents the relationship itself as an entity.
Sub-arcsecond accurate. We use the full VSOP87B series for Sun–Neptune, Meeus Chapter 47 (60 terms) for the Moon, and Meeus Chapter 37 for Pluto. Cross-checked live against NASA JPL Horizons.
Placidus is the default — the most widely used system in Western astrology. Equal houses and Whole Sign houses are also available via the API.
Transit planet positions are cached hourly. Each time you open the transit chart, it shows the current sky at that hour overlaid on your natal chart.
The Solar Return is cast for the exact moment the Sun returns to its natal longitude each year — precise to within seconds. It changes annually and is used to forecast themes for the coming 12 months.
Progressions use symbolic time (1 day = 1 year) to show how your inner nature evolves. While the natal chart is fixed, your progressed chart moves slowly — the progressed Moon changes sign every 2.5 years, for example.
All Western charts use the tropical zodiac (based on the seasons, not fixed stars). For sidereal astrology (Vedic/Jyotish), see the Vedic chart suite — coming soon.

Sun, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune: VSOP87B full series (Bretagnon & Francou 1987)

Moon: Meeus Astronomical Algorithms Chapter 47 — full 60-term series

Pluto: Meeus Chapter 37 — trigonometric series (43 terms) + IAU 1976 precession

Transneptunian planets: Hamburg School mean motion from J2000 epoch

Ascendant & MC: GAST → LMST → atan2 quadrant-safe formula

House cusps: Placidus iterative (default), Whole Sign, Equal

Aspects: Major (conjunction 0°±8°, sextile 60°±6°, square 90°±8°, trine 120°±8°, opposition 180°±8°) + minor set

Solar Return: Newton–Raphson iteration on Sun longitude, converges in 3–5 iterations, precision <0.001°

Progressions: Secondary (1 day = 1 year), chart cast at progressed date with birth time and location

How This Works: Full engine breakdown + NASA JPL accuracy verification →

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