Reading guide
An introduction to synastry: reading two charts laid over each other
Synastry reads a relationship by laying two natal charts over each other. What it shows, and where to start reading.
Yuki 2 min read
Some friends pick up your mood without a word. With others there is real goodwill, yet the conversation never quite meshes. We use the word compatibility all the time, but a concrete way to look inside it is not widely known. Astrology has a method for exactly that: synastry, the technique of laying two charts over each other.
Laying two maps over each other
A natal chart is a map of the sky at the moment you were born. In synastry, two of these maps are placed on one wheel: one person’s planets on the inner ring, the other’s on the outer ring. Then you look at the angles (aspects) their planets form with each other.
Those angles mirror the dynamics that tend to arise between two people. When one person’s Venus sits close to the other’s Mars, a natural pull tends to appear. When one person’s Saturn makes a hard angle to the other’s Moon, being together can start to feel cramped for one of them.
Beyond romance
Synastry tends to call up images of love-compatibility tests, but it works far beyond that. Parent and child, work partners, friends of many years: wherever there are two people, synastry holds.
In a parent–child synastry, for example, the parent’s Saturn sitting on the child’s Sun can show a structure where the parent applies the brakes without noticing. Setting good-or-bad aside, just seeing the structure — “this force is at work here” — changes the texture of the relationship.
What to keep in mind when reading
Synastry does not hand down an answer about compatibility. One easy angle can coexist with a snag somewhere else, and judging a whole relationship from a single placement never works. The sound way to use it is to survey the whole chart and get a sense of where things flow easily and where friction tends to build.
A “difficult” placement does not mean the relationship is doomed, either. The places with friction are often exactly where two people change each other by facing it. The chart shows how the forces are arranged; what to do with them is up to the two of you.
Laying two charts over each other in Hoshidou
In Hoshidou, once two sets of birth data are registered you can display a synastry chart. The planets line up on the inner and outer rings with the aspects drawn as lines between them, so you can see at a glance where the pull is and where the tension sits. Try laying your chart over someone close to you — the texture of the relationship you already feel may find its words.