Synastry — Astrology glossary

Synastry is the comparison of two natal charts to study a relationship, usually romantic but applicable to any pairing. The technique overlays one person's planets and points onto the other's and examines the angles between them, noting where the two charts support, challenge, or ignore each other. It is the most common astrological method for assessing compatibility. In practice, synastry matters because it describes the dynamic between two people rather than either individual alone, showing the specific points of attraction and friction. For example, one person's Venus sitting on the other's Mars is read as strong mutual attraction, while one person's Saturn pressing on the other's Sun suggests a relationship that feels weighty or restrictive, with one partner experiencing the other as a source of limitation or duty.