What Is a Synastry Chart?

A synastry chart works like a “compatibility map.” It compares the natal charts of two people to identify how each person’s planetary positions interact with the other’s. By analyzing planetary aspects and angles, it reveals areas of harmony, tension, and growth potential within the relationship.

What Synastry Reveals

Planetary Aspects:

For example, if one person’s Venus forms a trine (a fluid and cooperative aspect) with the other’s Mars, this may indicate strong romantic and sexual compatibility. On the other hand, if there’s a square (a tense aspect) between one person’s Mercury and the other’s Saturn, challenges may arise around open and honest communication. These aspects are key in evaluating compatibility.

House Overlays:

This refers to where one person’s planets fall in the other person’s chart. It shows which areas of one’s life are activated by the other’s presence. Example: if your partner’s Sun falls in your 7th house (the house of relationships), and harmonious aspects are present, you may see them as an ideal partner or even a future spouse. If the aspects are challenging, they might feel like a rival — after all, the 7th house also represents “open enemies.”

Individual Impact:

Synastry shows how each person’s cosmic energies affect the other. This chart illustrates how two individuals coexist as separate, yet interconnected entities.

Why Use Synastry:

To understand attraction and compatibility
To identify areas of ease and challenge
To recognize opportunities for individual growth within the relationship

What Is a Composite Chart?

The composite chart represents the relationship as its own entity. It’s created from the mathematical midpoints between the planets of two people, generating a new chart — the “birth chart” of the relationship itself. Example: the composite Sun is the midpoint between both people’s Suns.

What the Composite Chart Reveals

Relationship Personality:

It offers insight into the essence of the relationship’s soul. It can indicate the purpose of the bond and how it is perceived by the outside world.

House Emphasis:

It shows where the couple’s energy is most focused. For instance, a concentration of planets in the 10th house may suggest a public or career-focused relationship, such as couples who work together — the so-called “power couples.”

Strengths and Challenges as a Unit:

Unlike synastry, the composite chart reflects how the relationship functions as an integrated system. It shows where the couple naturally thrives and where conscious effort will be needed for harmony.

Why Use a Composite Chart:

To explore the dynamic and purpose of the relationship
To understand how the relationship evolves over time
To observe external influences and challenges that affect the couple

Using Both Together

To fully understand a relationship, it’s best to analyze both the synastry and the composite chart.

Start with synastry, observing how the planets interact. This helps to understand mutual attraction, affinities, and friction points — showing how each person influences the other.

Then, analyze the composite chart to grasp the bigger picture of the relationship. Questions like: “What is the purpose of this relationship?”, “Where does it thrive?”, or “What are its greatest challenges?” begin to make more sense here.

Combine Both Charts:

Use the strengths shown in synastry to work through the challenges revealed in the composite chart — and vice versa.

Example: if synastry shows communication difficulties, the composite chart might have a crowded 3rd house (ruled by Mercury) with tense aspects, suggesting that the couple needs to make extra efforts to communicate clearly and empathetically.

Important: No chart determines the fate of a relationship. Couples with “difficult” charts can have incredible relationships — and the reverse is also true. What matters most is emotional maturity and the commitment to grow together.

Astrology is a tool for awareness, not a sentence. We always have free will to turn challenges into opportunities and evolve — or to let unconscious patterns weaken the relationship. The choice is always ours.

Flavia da Matta

Flavia da Matta is a psychotherapist specializing in psychological astrology and mindfulness. With certifications in Thetahealing therapy and membership in the Academy of Kabbalistic Astrology, her approach is unique and compelling.

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