Synastry & Compatibility
The Astrology of Relationships · Western Astrology
Synastry is the branch of Western astrology dedicated to relationship analysis. The word comes from the Greek "syn" (together) and "astron" (star): the reading of two charts together, overlaying them to see where one person's planetary placements make connections — harmonious or challenging — with the other's. Synastry is one of the oldest applications of astrology; its principles have been documented since at least the Hellenistic period and remain among the most consulted astrological techniques in the modern world.
What It Reveals
A synastry reading examines the aspects formed between one person's planets and the other's: where Person A's Venus falls in relation to Person B's Mars, where their Moons connect or conflict, how their Saturns interact (usually a key indicator of commitment and longevity), and whether their Suns are in natural harmony or tension. Key synastry indicators for romantic relationships include Venus–Mars contacts (physical attraction and desire), Moon–Moon and Moon–Sun aspects (emotional attunement and core compatibility), Venus–Venus and Moon–Venus contacts (shared values and pleasure), and Sun–Moon contacts (the classic indicator of deep complementarity). Saturn contacts are double-edged: they can indicate a serious, committed bond with a sense of destiny, but also restriction and a feeling of one person holding the other back. Jupiter contacts bring expansion, generosity, and optimism to the areas they touch. The North Node connections — when one person's planets conjunct the other's nodal axis — carry a strong sense of karmic significance, as if the two people have unfinished business from a previous chapter. The composite chart (a derived chart representing the relationship itself as a third entity) is often read alongside synastry for a complete picture.
How It Works
Both individuals provide their date, time, and place of birth. The two charts are overlaid and the inter-aspects are calculated. The reading focuses first on the most significant connections (conjunctions, oppositions, trines, squares), then on the house overlays (which houses each person's planets fall in the other's chart), and finally on the overall balance and dominant themes of the relationship dynamic.
Who It's For
Synastry is for anyone who wants to understand the astrological dynamics of an important relationship — romantic, professional, or familial. It is most commonly sought for romantic partnerships, but it is equally illuminating for business partnerships, parent-child relationships, and close friendships. Synastry does not predict whether a relationship will work — it maps the terrain. What you do with that terrain is always a matter of choice and consciousness.