Introduction to Synastry #
Synastry is the art of relationship astrology—comparing two birth charts to understand the dynamics between two people. Unlike composite charts (which blend two charts into one), synastry examines how one person’s planets interact with another’s.
What Is Synastry? #
When two people meet, their planetary energies interact. Your Sun might conjunct their Moon. Their Venus might square your Mars. These connections—called inter-aspects—describe the felt experience of being together.
Synastry answers questions like:
- Why do I feel so drawn to this person?
- Why do we keep triggering each other?
- What can we learn from this relationship?
- Where is our greatest compatibility? Our greatest challenge?
How Synastry Works #
Planetary Overlays #
Each person’s planets fall somewhere in the other person’s chart. If your Sun falls in their 7th house, you illuminate their partnership sector. If their Saturn falls on your Moon, their structure meets your emotional nature.
Inter-Aspects #
When planets from two charts form aspects (conjunction, square, trine, etc.), specific dynamics activate:
- Conjunctions: Intense merging of energies
- Trines and Sextiles: Easy flow and mutual support
- Squares: Friction that generates growth
- Oppositions: Polarity that creates attraction AND tension
Key Principles #
Every Aspect Has Gifts #
Even challenging aspects offer potential for growth. A square generates energy—the question is whether you use it constructively.
Context Matters #
One aspect doesn’t define a relationship. Look at the whole picture. Many supportive aspects can buffer challenging ones.
Mutual Reception #
Both people feel the aspect, though often differently. Your Sun conjunct their Moon affects both of you—you through solar expression, them through lunar reception.
Growth Orientation #
The best use of synastry is not to predict compatibility, but to understand dynamics that can be worked with consciously.
The Planets in Synastry #
Personal Planets #
- Sun: Identity, ego, vitality
- Moon: Emotions, nurturing, instincts
- Mercury: Communication, thinking
- Venus: Love, values, attraction
- Mars: Desire, action, assertion
Social Planets #
- Jupiter: Expansion, faith, generosity
- Saturn: Structure, commitment, lessons
The Nodes #
- North Node: Karmic direction, growth
- South Node: Past patterns, familiarity
How to Use This Section #
Explore the specific combinations:
- Aspect Articles: Sun to Sun, Venus to Mars, etc.—what each inter-aspect means
- House Overlay Articles: What it means when one person’s planet falls in another’s house
Remember: astrology describes energy patterns, not fate. Every relationship is what you make of it.
Calculate your synastry with our birth chart calculator.