What are you looking at in a synastry?
Synastry compares two natal charts and examines relationships between their placements. It is often shown as two wheels or a contact matrix. Astrology interprets these contacts as possible themes of interaction: communication, care, attraction, boundaries or shared projects. They are not objective measurements of love or evidence of someone’s feelings.
First distinguish sign compatibility from synastry. A general compatibility may compare two Sun signs as an introductory exercise. A synastry tool uses both sets of birth details to examine specific placements. Even with more detail, the reading remains interpretive and cannot guarantee a relationship’s future.
Before starting, define the relationship you want to explore. Friendship, partnership, family ties and professional collaboration raise different questions. A Venus–Mars contact need not imply romance when you are studying how two colleagues coordinate a project. Context belongs in the reading from the start.
Check both people’s details
Check each birth date, local time and location separately. Use clear labels such as person A and person B to avoid swapping placements. If one time is documented and the other approximate, note the difference. A calculator accepting both forms does not mean the data has the same certainty.
Uncertainty is asymmetric. If A’s time is known but B’s is not, A’s natal houses can be calculated while B’s remain unknown. Some of B’s planetary placements can cautiously be explored over A’s chart. B’s unknown angles must not appear as confirmed contacts.
Take particular care with the Moon when the birth time is missing. Its motion can change degrees, aspects and, on some days, its sign. Ignoring this could give false precision to a contact whose existence is uncertain. See the guide to chart without a birth time and keep the warnings in your comparison notes.
Read each chart separately first
Before examining lines between wheels, identify what belongs to each chart. Note Sun, Moon, Mercury, Venus and Mars; add the Ascendant and houses only when the data supports them. The aim is not two fixed psychological profiles, but familiarity with the vocabulary used in the contacts.
The same crossed aspect is not interpreted in isolation from the rest of the map. If a reading highlights Saturn in relation to the Moon, it is worth checking what specific positions are involved and what question you want to explore. It is not enough to read one alarming description and apply it to the entire relationship. General interpretations need nuance and may not be helpful for that link.
The guide of reading a natal chart reviews signs, houses, degrees and aspects. Synastry uses the same language with one decisive difference: one placement belongs to A and the other to B. Keeping these labels visible prevents natal aspects from being mixed with contacts between people.
Recognizing a cross-chart aspect
A cross-chart aspect is an angular relationship between a point in one chart and a point in the other. Identify both bodies, the angle and orb before interpreting. Two planets being in signs considered compatible is not enough: geometry is calculated from specific degrees.
Fictional example: A’s Mercury is at 8° Gemini and B’s Saturn at 10° Virgo. Their longitudes are 68° and 160°. The separation is 92°: a square with a two-degree orb. This verifies the geometry without inferring any personal story from it.
| Comparison data | What to record | What to avoid |
|---|---|---|
| A’s planet | Name and degree | Confusing it with B’s same planet |
| B’s planet | Name and degree | Assuming the reverse contact is identical |
| Aspect | Reference angle | Reading only a line’s color |
| Orb | Distance from the exact aspect | Mix tolerances of different tools |
| Uncertain time | Which placements may vary | Presenting a hypothesis as a confirmed contact |
The astrological aspects provide a vocabulary for comparison. A conjunction is not universally favorable and a square does not prove conflict. Interpretation depends on the symbolic functions involved and should be checked against how people actually relate.
Organize the reading around questions
Group contacts around your question. For everyday care, consider lunar themes; for exchanging ideas, Mercury; for preferences and agreements, Venus; for initiative and disagreement, Mars. These associations are not rigid divisions of a relationship, but they help avoid an endless list of aspects without context.
Contacts need not all carry equal weight. Studying two or three clear geometric relationships and discussing a real situation is more useful than reading twenty contradictory phrases. You may discard a description that does not fit instead of seeking another placement to justify it at any cost.
The next question should be practical: “When is it easy for us to discuss this?” or “What agreement would help us coordinate?” Not “Which planet is to blame?” People remain responsible for their behavior. Symbolic language loses usefulness when it avoids a necessary conversation or excuses unacceptable treatment.
Moon, Mercury, Venus, Mars and Saturn
Lunar contacts are often explored through care and living habits. Ask which forms of support each person understands and which need explaining. Do not infer family history or emotional wounds from a placement. If someone does not wish to share their history, the chart does not override their words.
Mercury opens questions about conversation, learning and disagreement. Venus may help explore preferences and reciprocity. Mars introduces initiative, desire and action. None establishes consent or actual attraction: those are known through communication and behavior, not an angle calculation.
Traditionally, Saturn is associated with boundaries, time and commitment. It can frame a discussion of responsibilities and expectations. Check that agreements are clear and freely chosen, rather than making the symbol an obligation to stay together.
House overlays differ in each direction
A house overlay examines where A’s placement falls in B’s houses. It needs B’s houses and therefore a sufficiently reliable birth time for B. The reverse procedure examines B’s placement in A’s houses. These are different questions and need not give the same result.
Imagine A’s Mercury in B’s ninth house. Within astrological symbolism, you might explore conversations about study, travel or ways of thinking. This does not place B’s Mercury in the same house of A’s chart or imply identical experiences. Keep the direction explicit.
The house system matters too. Comparing whole sign with another method may change some placements. Do not combine their interpretations as cumulative facts. Choose a setting and record its limits. The guide to astrological houses explains why wheels with identical planets can divide areas of life differently.
A practical example of reading together
Take up the fictional example of A's Mercury square B's Saturn. One possible interpretation could open questions about spontaneity in speaking and the need for precision. It does not prove that A is dispersed or that B is critical. To give context, imagine a scene: A quickly proposes ideas and B asks to define deadlines before committing.
Both people may feel misunderstood if they turn their preferences into judgments. A may hear the questions as rejection and B may perceive the proposals as lacking concreteness. The useful conversation would be to distinguish an exploration stage from a planning stage. They could agree to first gather ideas and then evaluate resources, without attributing intentions that the other person did not express.
Record the opposite situation too: B improvises and A asks for structure. This reminds you that roles are not permanent identities. A symbolic reading can offer an opening question, but agreements should meet real needs and may change with time.
What a compatibility percentage does not mean
Some tools summarize aspects as a score. This depends on a formula: included bodies, weighted contacts and assigned values. It is not a scientific probability of relationship success. Different services can give different percentages for the same births because their criteria differ.
If you see a score, ask what it summarizes. It may help navigation in an interface, but cannot replace contact details or justify a relationship decision. A high number does not erase value differences; a low one does not doom a respectful relationship.
Synastry cannot confirm faithfulness, duration, marriage or secret feelings either. Such promises exceed what the calculation can verify. Keeping this boundary makes room for questions open to conversation instead of definitive answers about another person’s freedom.
From a result to a conversation
Choose a theme and write a first-person question. For example: “When we plan, I need to know the timing; what works for you?” Share an interpretation as a possibility, not an explanation the other person must accept. If it does not resonate, leave it and explore another question.
A free synastry lets you start with the data. To explore contacts in your own context, continue to your relationships in My Universe. Keep the context and review what information you share. Knowing someone’s birth details does not authorize publishing their chart or personal information.
Frequently asked questions
Are synastry and composite charts the same?
No. Synastry compares two charts. A composite chart builds a map from midpoints of both charts’ placements using another technique. Do not mix their aspects or houses. If a tool displays one wheel, check its calculation type before interpreting.
Does an opposition mean we are incompatible?
No. Opposition is an angular relationship often read astrologically as polarity. It is not an objective measure of incompatibility. It can help explore differences, but relationship quality depends on factors an isolated aspect cannot describe.
Can I use synastry for a friendship?
Yes, with questions suited to the relationship. Communication, shared interests and everyday coordination may be useful themes. Avoid automatically applying romantic or sexual interpretations to contacts that can appear in any chart comparison.
Can I read it if someone does not know their birth time?
Yes, partially. Omit angles and houses that depend on the unknown time and treat lunar contacts cautiously. State what belongs to each person. The comparison should show uncertainty, rather than fill it with an invented time.