What is synastry? How to read a relationship analysis

Looking at two people's signs and calling them "compatible" or "incompatible" is quick, but it often falls short. That's because the Sun sign is only one part of a person's chart. The way to explore relationships astrologically in more depth is synastry. Synastry lays two people's birth charts on top of each other and looks at how the planets speak to one another. Let's look together at how synastry works, and what it can and cannot show. To see your own synastry, you can use the synastry tool.

What is synastry?

Synastry is the comparison of two people's birth charts. It examines the aspects one person's planets make to the other's planets, and which of the other person's houses those planets fall into. This shows in which areas two people touch each other's lives, and where they are likely to experience flow or friction.

Sign compatibility usually compares only the two Sun signs. Synastry, by contrast, considers all ten planets, the houses and the aspects together. Two people whose Sun signs look incompatible can be very compatible thanks to their Moon and Venus connections, and the reverse is also possible. For a general overview based on Sun signs, the sign compatibility page is a good fit; for depth, synastry is the right tool.

The data you need for synastry

You need the date, time and place of birth for both people. Without the birth time, the rising sign and house placements are not reliable, and since a large part of synastry rests on the houses, the time is especially valuable here. If the time is unknown, it is safer to focus on the aspects between the planets.

How is synastry read?

Cross-aspects

The heart of synastry is the cross-aspects: one person's Sun looks at the other's Moon, one person's Venus looks at the other's Mars. The connections that receive the most attention are these:

Sun and Moon: When one person's identity matches the other's emotional needs, a sense of "I'm home" develops in the relationship. Many astrologers say they often see this connection in long-lasting relationships.
Venus and Mars: The meeting of love and desire shows attraction and chemistry.
Moon and Moon: The harmony of emotional reactions and needs. The same sign or harmonious aspects bring ease to daily life.
Mercury and Mercury: The harmony of communication styles. How well you understand each other and can talk things through depends on this.
Saturn connections: Responsibility, continuity and boundaries. They can be challenging, but they can also add stability to the relationship.

For how aspects are interpreted, the aspects guide offers a starting point.

House placements

Which houses one person's planets fall into in the other's chart shows which area of life the relationship affects. If your partner's Venus falls in your seventh house, this person may be a "relationship" figure for you. Someone whose Saturn falls in your fourth house may bring responsibility around home and family. The meanings of the houses are covered in the houses guide.

Lunar nodes

Some astrologers also examine the connections between the lunar nodes in the two charts. Aspects involving the nodes are interpreted as a bond that makes the relationship feel "fated". This interpretation carries different weight in traditional and modern schools of astrology, so it should be treated as a possibility.

A short example

One person's Venus is in Aries and the other's Mars is in Leo; both are fire signs, and the planets form a trine. For this couple, attraction develops easily and the relationship moves along in a fluid, cheerful way. If, in the same couple, one person's Moon is in Taurus, the other's Saturn is in Leo, and these two planets square each other, the Moon person may at times feel criticised or restricted. So the same synastry shows both ease and an area that needs work. In real charts, examples like these are read alongside many more connections.

Synastry and the composite chart

Synastry compares two separate charts. A composite chart, on the other hand, creates a third chart from the midpoints of the two charts and reads the relationship itself as a separate entity. Synastry asks "what do you do to each other?", while the composite chart asks "what does this relationship say in its own right?" Reading the two together gives the most complete picture. You can create a composite chart on the composite chart page.

Are challenging aspects bad?

No. Squares and oppositions create friction, but that friction is often what keeps a relationship moving. A synastry with no tension at all can lead to a relationship that stagnates. What matters is being aware of the challenging aspects and being able to talk about these issues openly. In the same way, harmonious aspects don't mean no problems will arise; in a relationship that is too comfortable, the drive to grow can fade.

How should synastry be used?

Synastry is not a verdict but a conversation starter that helps two people understand each other. Many astrologers recommend using synastry not with the question "will this relationship last?" but with "how can we understand each other better?" The lifespan or quality of a relationship doesn't depend on any single astrological indicator. Communication, shared values, mutual effort and timing are far more decisive.

Is it only for romantic relationships?

Synastry isn't limited to romantic relationships. The same method can be used to explore friendships, family ties, business partnerships and parent-child relationships. Moon connections between a mother and child, or Mercury and Saturn aspects between two business partners, can offer clues about how the relationship works day to day. Which planets come to the fore changes with each type of relationship: in a romantic relationship Venus and Mars may be more decisive, in a working relationship Mercury and Saturn.

A simple reading order

Note the Sun, Moon and rising sign of both people. Then look at the aspects between one person's Sun and Moon and the other's Sun and Moon.
Look at the Venus and Mars connections; attraction and love language show up here.
Assess the harmony of communication styles through the Mercury aspects.
Pay attention to hard aspects from Saturn and the outer planets to the personal planets; these describe the relationship's tests.
Check the house placements: which area of your life does your partner set in motion?
Sum up your findings in two sentences: what does it strengthen, and what does it challenge?

Synastry and timing

A relationship between two people changes over time. Synastry shows the placements at the moment of birth; today and in the future, the planets trigger both charts in different ways. To understand the phase your relationship is in, you can look at the transit chart and review each person's chart separately. To get started, all you need is to cast your own chart on the birth chart page.

Frequently asked questions

What is the difference between synastry and sign compatibility?

Sign compatibility mostly compares the two Sun signs. Synastry, by contrast, considers all of both people's planets, their houses and the aspects between them, so it gives a much more detailed picture.

Is a birth time required for synastry?

It isn't essential, but if the time is known, the rising sign and house placements can be read too. If the time is unknown, it is safer to focus on the aspects between the planets.

Do challenging aspects in synastry mean the relationship will end?

No. Challenging aspects create friction, but they can also be dynamics that help the relationship grow. Whether a relationship lasts depends far more on communication and mutual effort.

synastry
relationship analysis
cross-aspects
composite chart
sign compatibility

Comments

No comments yet. Be the first to share your thoughts.

Reading your relationship through synastry