Relationships
Synastry
Synastry is the practice of reading two natal charts against each other to see how two people interact. It lays one chart over the other and looks at the aspects between them: your Venus to their Mars, your Moon to their Sun, and so on. A trine or sextile between the two tends to feel easy, a square or opposition more charged, and the mix is what gives a connection its character.
Synastry is the astrology of two. Instead of reading one chart on its own, you lay two natal charts side by side and study how they touch, which of your planets reach out to which of another person's. It is the technique most people mean when they ask whether two charts are compatible.
Cross-measuring two charts: aspects and house overlays
Both charts are ordinary birth charts, computed from two real births. Synastry adds no new astronomy; it cross-measures the angles between them. You look at the aspects one person's planets make to the other's, so your Venus to their Mars, your Moon to their Sun, and note which are close and which are wide. You also see which of their houses your planets fall into, which shows where you tend to activate their life. Those two layers, the planet-to-planet aspects and the house overlays, make up a synastry reading.
Venus, Mars, Sun, Moon and Saturn contacts
Tradition assigns meaning to the pairings. Venus and Mars contacts are read as attraction, Sun and Moon contacts as a feeling of home, Saturn contacts as commitment and weight, and the outer planets as fascination or upheaval. Soft aspects between two charts are read as ease and flow, hard ones as friction that can be either exciting or wearing. No single contact is taken to make or break a match; the pattern across the whole comparison is what counts.
One person's Venus on the other's Sun
Suppose one person's Venus sits right on the other's Sun. That contact is read as warm and affectionate, the Venus person delighting in the Sun person and the Sun person feeling appreciated. Add a Mars square between them and you get attraction with an edge, a spark that can tip into friction, which is why readers weigh the whole set of contacts rather than any one.
Synastry, composite and sun-sign matching
Synastry is not the same as a composite chart; synastry compares two separate charts, while a composite merges them into one. It is also far more than sun-sign compatibility, since it uses every planet and point in both charts, not just the two Suns. And a difficult aspect or two does not doom a relationship, because context decides how a contact actually plays out.
Two charts compared side by side
The NovaOracles compatibility tool compares two charts and finds the aspects between them, the compatibility guide explains how to weigh them, and compatibility and synastry explained goes deeper.
FAQ
Frequently asked questions
What is synastry in astrology?
The technique of comparing two birth charts to see how two people connect. It looks at the aspects between one person's planets and the other's, and at whose houses each activates.
What is the difference between synastry and a composite chart?
Synastry keeps two separate charts and studies the contacts between them. A composite merges the two into one chart that stands for the relationship itself.
What are the most important aspects in synastry?
Contacts between the Sun, Moon, Venus and Mars carry the most weight, read for warmth, ease and attraction. Saturn contacts add commitment and staying power.
Sources
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The Journal
Compatibility and synastry, explainedRead the guide
Compatibility and synastrySee how this shows up in your own chart.
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