What Is Synastry?
Synastry compares two natal charts by looking at the aspects one person's planets make to the other's. Sun–Moon, Venus–Mars and Moon–Moon contacts are especially important for romance; Mercury contacts show communication; Saturn contacts show commitment and lessons.
How to Read Your Results
- Trines and sextiles — natural ease and support.
- Squares and oppositions — attraction, friction and growth.
- Conjunctions — strong bonding; tone depends on the planets.
- The harmony index is a simple ratio — a conversation starter, not a verdict.
Synastry vs Composite Charts
A composite chart blends two charts into one chart for the relationship itself. Synastry, used here, shows how two individual charts interact.
Key Synastry Aspects for Love
| Contact | What it suggests |
|---|---|
| Sun–Moon conjunction or trine | Classic harmony; feeling understood |
| Venus–Mars | Romantic and physical chemistry |
| Moon–Moon | Emotional rhythm and domestic comfort |
| Saturn to personal planets | Commitment, responsibility, sometimes heaviness |
| Mercury–Mercury | How easily you talk and understand each other |
| Outer planets to personal planets | Transformative, intense, unforgettable bonds |
Element Compatibility
Our calculator compares your Sun, Moon and Venus elements. Same or complementary elements (Fire–Air, Earth–Water) tend to flow easily; squares between elements bring spark and friction.
Want a Deeper Compatibility Reading?
An astrologer can look at house overlays, composite charts and timing. See the best astrology reading sites.
Frequently Asked Questions
Does a low harmony index mean we're incompatible?
No. Challenging aspects often create attraction and growth; many lasting couples have plenty of squares.
Do we need birth times?
Not for planet aspects; birth times add house overlays and more precise Moon positions.
What is the most important aspect in synastry?
Sun–Moon, Venus–Mars and Moon–Moon contacts are the classic indicators of romantic compatibility.
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