Astrology 101
What Is Synastry?
Synastry is the branch of astrology that compares two people’s birth charts side by side — overlaying one person’s planets onto the other’s to see where they align, clash, or complement each other. It’s the traditional astrological approach to reading compatibility between two people.
How Synastry Works
An astrologer takes both people’s birth charts and draws the angles (called aspects) between one person’s planets and the other’s. A tight, harmonious angle between two planets suggests those two placements work well together; a tense angle suggests friction. The overlay also shows which of your houses the other person’s planets land in — which points to which parts of life the relationship is likely to be felt in most.
What Synastry Looks At
A few placement pairs matter more than others in a synastry reading:
- Sun–Moon connections — often considered the core of romantic compatibility: one person’s identity meeting the other’s emotional world.
- Venus–Mars connections — the classic attraction signature, linking how one person loves with how the other pursues.
- Moon–Moon connections — whether two people’s emotional needs and rhythms naturally line up.
- Mercury–Mercury connections — how easily two people communicate and think through problems together.
The Five Core Aspects
- Conjunction (0°)
- Two planets sit in the same spot. Their energies blend and intensify — for better or worse, depending on which planets are involved.
- Sextile (60°)
- An easy, opportunity-based connection. It’s supportive, but tends to need a little initiative from both people to actually use it.
- Square (90°)
- Friction and tension. Square aspects are uncomfortable but often where the most growth in a relationship happens.
- Trine (120°)
- Natural harmony. Things flow easily here — sometimes so easily that the connection is taken for granted.
- Opposition (180°)
- A push-pull polarity. Opposition placements often mean the two people balance or mirror each other, for good and for friction.
The Limits of Synastry
Synastry is one lens, not a verdict. No single aspect makes or breaks a relationship — a chart can point to easy chemistry or to real friction points worth being aware of, but it can’t account for communication, timing, effort, or choice, which shape a relationship at least as much as the sky did on the day either of you was born.
Astrology is a lens for reflection, not a guarantee of outcomes — use it for insight into yourself, not as a substitute for professional advice.