Synastry is the astrological technique of comparing two birth charts to see how two people interact — where they feel naturally in tune, where there is attraction, and where they might clash. It goes much further than "are our sun signs compatible?", because it looks at every planet in both charts.
What you need for a synastry reading
For each person: date of birth, place of birth and — ideally — time of birth. Without birth times an astrologer can still compare most planets, but not the rising sign or the houses, which add a lot of detail.
What astrologers look at
- Sun and Moon. How your core selves and emotional needs fit together. Moon contacts are often read as a sign of emotional comfort (see moon sign compatibility).
- Venus and Mars. Romance and attraction. Venus describes how you love, Mars how you pursue and assert yourself. Contacts between one person's Venus and the other's Mars are classic signs of chemistry.
- Mercury. How easily you understand each other in conversation.
- Saturn. Commitment and responsibility — and sometimes a feeling of heaviness. Saturn contacts are often present in long-lasting relationships.
- Aspects. The angles between planets in the two charts. Harmonious angles (trines, sextiles) suggest ease; tense angles (squares, oppositions) suggest friction that can also create growth and attraction.
Easy vs challenging connections
A chart comparison full of easy contacts can feel comfortable but sometimes lacks spark. A comparison with some tension can feel exciting but needs more effort. Most real relationships have both — and astrologers generally read challenging contacts as areas to understand, not as reasons a relationship can't work.
Synastry vs sun-sign compatibility
Sun-sign compatibility (like the matches on our zodiac pages) is a quick snapshot based on one placement. Synastry looks at the whole picture. Two people whose sun signs are "incompatible" can have a very harmonious synastry, and the opposite is also true.
What synastry can't tell you
A chart comparison describes potential and dynamics, not destiny. It cannot tell you whether someone will commit, cheat or come back — those depend on people's choices. A good astrologer uses synastry to help you understand the relationship, not to pass a verdict on it. Readings on Vaelory are for entertainment and self-reflection.
Frequently asked questions
Is synastry accurate?
Synastry is a descriptive tool, not a scientific test. Many people find it a helpful way to talk about their relationship and understand differences, which is how astrologers on Vaelory use it.
What is the difference between synastry and a composite chart?
Synastry compares two charts side by side. A composite chart blends them into one chart that represents the relationship itself. Many astrologers use both.
Can I do synastry without my partner's birth time?
Yes, partially. Most planets can be compared with just the birth date, but the rising sign and houses will be missing.