Astrological compatibility is not a ranking of which Sun signs belong together. It is the study of how two complete natal charts interact—where connection feels natural, where differences require translation and what each person awakens in the other.
What is synastry?
Synastry compares the planets and angles in one birth chart with those in another. An astrologer looks at cross-chart aspects, house overlays and repeated themes. The goal is not to produce a percentage score, but to describe the relationship’s patterns.
A strong connection can contain both ease and tension. Harmonious aspects may support affection and understanding; challenging aspects can create attraction, growth or recurring conflict. Context, maturity and choice determine how a pattern is lived.
Emotional compatibility: Moon to Moon
The Moon describes instinctive needs, habits and ways of finding safety. Moon connections often show whether two people naturally understand each other’s emotional rhythm. Compatible elements can make support feel intuitive, while contrasting Moons may need clearer language and more deliberate care.
Difference is not incompatibility. A fire Moon may process feelings through direct action while a water Moon needs privacy and emotional depth. The relationship becomes stronger when each person recognizes that the other regulates experience differently.
Communication: Mercury connections
Mercury aspects describe how two people exchange ideas, interpret language and resolve misunderstandings. Flowing Mercury contacts can make conversation easy. Squares or oppositions may produce stimulating debate, but can also create repeated friction if each person assumes their own communication style is universal.
Connections between Mercury and the Moon matter because thoughts and feelings must reach one another. Mercury–Saturn contacts can bring seriousness and reliability, yet may require care around criticism. Mercury–Uranus can feel exciting and inventive while needing room for unpredictability.
Attraction: Venus and Mars
Venus shows what a person values, enjoys and receives; Mars describes pursuit, desire and assertion. Contacts between them can create chemistry, but attraction alone does not guarantee emotional security or long-term ease.
Venus connections also describe affection, taste and shared pleasure. Mars connections show how two people energize or provoke one another. Their signs, houses and other aspects explain whether intensity becomes cooperation, play, competition or conflict.
Commitment and longevity
Saturn is often prominent in lasting relationships because it symbolizes time, responsibility, boundaries and commitment. Supportive Saturn contacts can create reliability and the willingness to build. Difficult contacts may feel restrictive or critical unless both people handle responsibility consciously.
Long-term potential is never shown by Saturn alone. Emotional responsiveness, communication, values, life circumstances and mutual effort all matter. Astrology can describe the structure of a bond; it cannot replace consent, respect or real-world compatibility.
House overlays: where someone enters your life
When another person’s planets fall into your houses, they activate those life areas. A partner’s Sun in your 4th house may highlight home and belonging. Venus in your 5th can emphasize pleasure and romance. Saturn in your 10th may bring seriousness to vocation or public direction.
Overlays are experienced from each chart’s perspective, so the relationship can feel different to each person. Both directions must be read.
Common compatibility myths
“Matching elements guarantee a good relationship.”
Shared elements may create familiarity, but they do not guarantee aligned values, healthy behavior or emotional skill.
“One difficult aspect means the relationship will fail.”
No single aspect decides the outcome. Repetition, the rest of both charts and how people respond to the pattern are more important.
“No major aspects means no connection.”
House overlays, angles, rulers and subtler contacts may still be meaningful. The real relationship also exists beyond astrology.
How to read compatibility responsibly
Begin with each natal chart separately. Then compare the Moon, Mercury, Venus and Mars, followed by the Sun, angles and Saturn. Look for repeated themes across aspects and overlays. Describe needs and dynamics in neutral language rather than predicting certainty.
Asteria’s Compatibility Report compares two complete charts across emotional connection, communication, attraction, strengths, challenges and long-term themes. Explore the Compatibility Report →