Compatibility and synastry
Astrological compatibility is not about matching two sun signs. It is read from two whole charts: synastry, the aspects between one person's planets and the other's, and the composite, a single chart for the relationship itself. This guide gathers the terms, the tool and the reading that explain how two charts are compared, as a mirror rather than a verdict.
How does synastry work?
Compatibility here starts with two full birth charts, not two sun signs. Synastry lays them over each other and reads the aspects between them: your Moon to their Venus, their Mars to your Sun, one person's planets angling to the other's. The composite chart takes a different route, building a single chart from the midpoints of the two, read as the relationship itself rather than either person. One shows how you meet day to day; the other shows what the two of you become together. Neither is a verdict on the match: both are simply two charts, read side by side.
The aspects two charts make
The aspects are the angles those planets make, and each has a flavor. A conjunction, zero degrees apart, blends and intensifies two planets. An opposition, across the chart, pulls in two directions and asks for balance. A square, a quarter-circle apart, brings friction that pushes for growth. A trine, a third of the circle, flows easily, sometimes so easily it is taken for granted, and a sextile offers a gentler opening if you take the first step. In a comparison the mix matters more than any single angle: the flowing aspects show where you rest, the hard ones show where you sharpen each other. Count the pattern, not one aspect: a single hard angle rarely decides anything on its own.
The harmony index, and its limits
NovaOracles reads synastry from real astronomy and offers a simple harmony index alongside a warm, honest read of where you flow and where you spark. Treat the number as a summary, not a scorecard: a low one is not a warning, and a high one is not a promise. Every strong pair has its squares, and plenty of easy matches never catch light. The chart describes a dynamic between two people; the two people decide what to do with it. What looks difficult on paper is often the very thing that keeps two people interested.
Where to go next with compatibility
The compatibility calculator compares two sets of birth details and returns the aspects, the harmony index and the reading, with no account and nothing sold as fate. It helps to know each person's own chart first: the birth chart calculator draws either one, and the guide to the big three is a good place to start reading a single person. Nothing here is a prediction about a relationship. It is a language for talking about one, and the point is a better conversation, not a score to pass or fail.
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