Synastry places two natal charts in relationship and measures aspects between factors belonging to different people. Unlike a composite chart, it preserves the identity of each person’s planets and angles, allowing the reader to ask how two distinct styles respond to each other.
What an interchart aspect means
A conjunction, square, trine, sextile or opposition between two people’s positions can be interpreted through the planetary functions involved. Moon–Mercury may suggest ways feelings and communication connect; Venus–Mars may raise questions about attraction and initiative; Saturn contacts can draw attention to expectations and durability. None of these contacts has a universally positive or negative meaning.
Why birth data and context matter
Exact birth time becomes important when comparing angles and houses, although some planetary contacts remain calculable without it. Interpret close aspects first, identify which person’s planet contributes each theme and avoid assuming that both people experience the contact identically. A challenging contact can be constructive with communication; an easy one can be neglected.
From separate charts to a relationship reading
Read each natal chart on its own before the comparison. Then prioritize the luminaries, personal planets, angles and repeated themes, adding house overlays and combined charts only after the basic interchart pattern is clear.
Further relationship techniques
Continue with the Compatibility & Synastry guide, which places zodiac compatibility, interchart aspects and house overlays in a single interpretive framework.