Synastry — the Astrology of Relationships

SYNASTRY means “together with the stars”. It is the art of analysing a relationship of two or more people — for instance, a couple planning to marry, parent/child relationships, business relationships, student/teacher relationships. The individual natal charts are compared and from this can be gauged the degree of compatibility or incompatibility and where areas of conflict or misunderstanding are likely to arise.   

I am often asked questions like “I’m a Virgo and my partner is an Aries – that’s not right is it?” My answer to this is that you can be compatible with whomsoever you wish to be compatible with!

In this article I hope to finally put to rest “all that Sun-sign stuff” you may read about that “Aquarians are only compatible with Geminis or Librans” (all sharing the Air element, so forming a harmonious trine), “Taurus and Leo (with the Fixed quality in common forming the difficult square aspect) are incompatible, avoid these relationships”, “Scorpio male seeks Pisces female with view to long lasting relationship”, etc, etc.

Aquarians may well be extremely compatible with their Gemini and Libran counterparts, on a very superficial or mental level, but for long-lasting, enduring, relationships there has to be more to it than that! Taurus and Leo are indeed two very fixed signs and their fixity may lead to a bit of head bashing (figuratively speaking) at times, but the Leo with his Moon in Taurus, conjunct her Sun in Taurus would tell you that the contact and the attraction is strong.

And what about those people we meet for the first time, and “just can’t stand”, their very presence rubs us up the wrong way. These people have links, astrological ties, with us too and by finding out what they are can be a learning experience for us all. Often we see in others what we don’t like about ourselves, won’t even admit to in ourselves, so we dislike that person for making us aware of these personal shortcomings. In the majority of these instances you will find a contact to your Moon.

She brings out the worst in me!” is another cry from the heart so often heard. What is it in her chart that makes such a close contact in mine that does that? Or on the other hand you meet someone for the first time and suddenly you find yourself talking non-stop and know more about that person in the next half-hour than you do about your best friend? Definitely an agreeable astrological contact between your two charts there. Or the student whose Saturn contacts my Mercury — for sure I will have to work hard with that one! Or those people you feel you’ve know before, and know well — maybe you will find that their Mercury is in the same degree and sign as your ascendant, for what is being brought out is what you subconsciously know so well about yourself, what you have lived with since the moment you were born, so feeling you have known this “stranger” all your life.

In this article we will concentrate on personal relationships, those one-to-one relationships that involve the union of two people whether by marriage or by their stating a commitment to each other.

The only way to assess charts for the purpose of Synastry is to thoroughly understand the natal chart first. After knowing what each individual needs, the inter-relation of one chart with the other becomes possible.

The 7th House shows what we look for in a partner, it shows those qualities which we feel may be lacking in ourselves so we look for a partner to supply them. The partner is a mirror of what we need to become whole, to complement what we lack. This may be represented by planets in the 7th House or ruler of the 7th. The sign on the 7th House cusp, as well as the sign any planet/s either in or ruling the house of course also needs to be considered.

Sun in 7th House

This may indicate someone who “puts their sense of identity in the partner’s hands”, the partner takes all the limelight, while the other basks in their glow. Their life revolves around the partner (Sun as the centre of the chart). It is important for the Sun in the 7th person to be aware of themselves as an individual, to shine in his or her own light, to learn to be a mutual admiration society, to take turns at being the “star performer”.

Moon in 7th House

The “mother” in us — often with the Moon in the 7th you find the “mother/baby” dilemma — either a mother looking for a child to take care of, or a child looking for a mother to take care of them. Seeking the “mother image” through the partner. Here, nurturing and caring for one another on an equal basis is necessary. Learning to care for one’s one self and self-nurturing also needs to be brought into perspective.

Mercury in 7th House

Mercury wants a partner on the mental level, someone to communicate with, someone who is into varied interests and idea orientated — a meeting of the minds. The Gemini side of Mercury wants variety and could attract partners who are superficial and off in all directions. The Virgo side of Mercury is a critic who needs practicality and discrimination. Mercury in the 7th needs to be aware of their own communicative skills and intellect, to learn to be able to express their own ideas rather than letting the partner do it for them.

Venus in 7th House

Venus the planet of relationships in the relationship sector of the chart, is naturally drawn towards cooperation with others (although sign and aspect may modify this). They desire to make a social and beautiful relationship where both partners are equally supportive in creating a harmonious and aesthetic environment.

Can be inclined to attracting “nice” people; sweet, charming, gracious, who may never express an opinion for fear of disrupting the harmony. Or on a more superficial level, may just desire someone “nice to look at”; or may indicate high expectations of being taken care of with comfort and ease “in the style to which they have been (or would like to be!) accustomed”. Venus in the 7th needs to be aware of their own beauty, to be aware of their physical attractiveness rather than looking for it in a partner.

Mars in 7th House

Often attracts very competitive, independent people, supplying the energy they feel may be lacking in themselves. They may feel they lack self-assertion so look for the partner to supply it for them, which if exaggerated could result in some form of violent behaviour. Or attracting someone who is seen to be constantly competing with them. Mars in the 7th needs to be aware of their own strengths, their own sense of competitiveness; being involved in healthy competition where either partner can win some or lose some — the winning or losing is not unbalanced yet the competitive streak is alive.

 Jupiter in 7th House

Truth and philosophy play an important part in their development with a partner, and Jupiter in the 7th could look for “God” or a guru in the partner, someone who will supply them with all the answers. Jupiter needs freedom, needs space. In the 7th, could attract the free soul who is always off in a quest for truth; or may dodge the serious relationship in an exaggerated desire to be free.

 Jupiter often aims for the unobtainable, in search of an ideal, something bigger and better around the corner or across the sea. They need to be aware that the truth is to be found within themselves. To respect each other’s need to have their own space; to learn to grow together, through each other.

Saturn in 7th House

Saturn is the “father figure” and could indicate a “father/child” situation. Attracting a partner who may seem authoritative, limiting, cold and too responsible; feeling restricted or limited by the partner. Saturn is responsibility and in the 7th demands they take charge of their side of the relationship — a need for a mutual sharing of responsibilities so that the partner is not seen in such a limiting or restricting light.

Commonly found with Saturn in the 7th is an age difference between the partners (say 7 years or more) or either getting married very early in life (say before 20) or later in life (around 30 or later). An excellent example of this is with Lesson 12’s homework chart: this lady with Saturn in the 7th married at 19 years of age to a man 10 years her senior. She married again some years later at age 45 to a man five years her junior!

Uranus in 7th House

Uranus is a freedom symbol with the urge to be different and liberated — in the 7th may end up attracting unusual and liberated people; exaggerated may attract the eccentrics, the rebels. There is a restlessness and need for excitement in the marriage — which explains why many astrological textbooks state categorically that  "Uranus in 7th = divorce”. Obviously, the need for Uranus in the 7th is to be aware of their own uniqueness while accepting the partner’s; getting in touch with the fact that they are unusual, different and highly individualised — then they have less need for those qualities in a partner.  Balancing this in the relationship means two individuals accepting each other’s uniqueness.

Neptune in 7th House

Neptune searches for the infinite love, often dreaming and make-believing of the romantic hero. They look at their partner through rose-coloured glasses and when in time they turn out to be only human after all, the “perfect” mate winds up far from its ideal.  The Neptune idealism may also extend to the saviour / victim situation — attracting those people who they can “save”: the alcoholic, the handicapped, or just someone extremely timid, who will give them the opportunity to save them. The “sacrifice everything for a partner” is another side of, the situation where they feel they must suffer and be self denying to deserve their idealistic love.

Neptune in the 7th needs to be aware they glamorise people so that they can be more realistic in their expectations. They need to be idolised so the partnership needs mutual idealisation. The relationship wants romance but not the unhappy endings. The perfection they seek is within; not out there on a movie screen, in a bottle, or their dreams.

Pluto in 7th House

Often the Plutonian person holds on to their deep feelings, reluctant to express them.  Pluto is power, and manipulation, and often in the 7th attracts those people who make them feel they are constantly “in their power” and there is no way out but death (to take it to extreme). These power struggles within the relationship can turn into deep, intense emotion, possessiveness or obsession. Pluto in the 7th often indicates a partner who is “abnormal “or “special” in some way, where the healing side of Pluto is used to transform, regenerate — to heal — the partner. This of course can be used in a very positive sense. Self-empowerment is the key for Pluto in the 7th.


·       The lack of a Quality or an Element

It is fascinating to see the charts of two people, where one makes up for the lack in the other. For instance where one has an absence of Air in his chart, attracting (or being attracted to) the person with a predominance of Air in her chart: looking for the quality in the partner that they feel is lacking within themselves. I have found this factor to be so common when comparing the charts of two people, that I feel I can almost state categorically that when one chart lacks an Element or a Quality they will seek a partner who supplies that missing factor.

Another instance along these lines is with the Overloaded House* charts, with the natural ruler of the Overloaded House being strongly represented in the partner’s chart. An excellent example of this is shown in the charts for Prince Charles and Princess Diana. He has an Overloaded 4th House, bringing out the Cancerian influence. Diana’s Sun and Mercury are in Cancer. Interestingly, Charles’ long-time lover and now wife, Camilla Parker-Bowles is also Cancerian.

Chart 1
Inner wheel & house cusps: Prince Charles
Outer wheel: Princess Diana


Chart 2
Inner wheel & house cusps: Princess Diana
Outer wheel: Prince Charles

Interesting to note too, that his Overload does not “overload” her in any way. The four planets in his Overload are distributed through her 9th, 10th and 11th houses. Often when comparing two charts in this way, you will find one’s overload filling up an entire house of the partner, which would indicate a feeling of the partner’s not being able to handle an area of life that previously had caused no problems.

 ·       See if one person’s planet/s fills the partner’s empty house

By filling somebody’s empty House, a new dimension of understanding is brought to that area. To Diana, Charles brought the meaning of friendship (his Sun falling in her empty 11th House), love of family, emotional security and stability (his Moon in Taurus falls in her empty 4th House). By marrying him a fairytale fantasy was woven around her, sparking the imagination and romance of millions of people around the world — his Venus / Neptune in Libra fills her empty 9th House.

She brought to him added responsibilities as far as his work or sense of duty is concerned: her Saturn falls in his empty 6th house. Jupiter is also in the 6th but only minutes away from the 7th cusp. Looking at this is a positive light this has the potential to bring growth, understanding and development, for the marriage to be of great benefit to him as a person. This would certainly appear to have been so in the early days. With her Sun in Cancer filling his empty 12th House this may indicate her desire to take him out of the limelight, to insist on a need for privacy in their personal lives — or her sense of isolation with him literally putting her in the background of his life. With her Moon falling in his empty 8th, she brings him the potential for emotional understanding where shared resources are concerned. Her need for emotional satisfaction is very much centred around joint financial issues. If we are to believe the many reports about this famous relationship, these needs appeared to have been denied her — and a consideration of the planetary aspects below attests to this.

 House positions are very revealing. The cross placements of planets can stimulate or stifle the area in question.

 ·       Look for new configurations when merging the two charts

This is one of the most effective says of judging compatibility. You will find instances where the planet in one chart makes a major configuration in the other’s. This can represent stimulation or irritation, willingness to work on a relationship and much more. By merging two charts, a square can become a T-square, creating a new stress point not always easy to handle; unless the couple are very easy-going and need a good push or shove, then a T-square is the ideal solution. One person’s T-square can become a Grand Cross — now there are two oppositions instead of just one. Looking at this positively, it could be seen as giving better direction and balance, and could be easier to handle than the T-square. Charles’ Sun at 22oScorpio creates a Grand Cross in Diana’s chart, filling in her T-square between the Moon at 25oAquarius, Venus at 24oTaurus and Uranus at 23oLeo. Being in the fixed signs, it could also indicate that he has made her all the more determined to get her own way!  Looking at this powerful pattern, one can understand the reports or her constant frustration, her emotional outbursts and mood swings, as it accentuated her natal Moon opposition Uranus.

When one person’s trine becomes a Grand Trine through joining two charts, more harmony and flow is created. This can be very helpful and inspirational but does not necessarily guarantee a good or long-lasting partnership. More binding would be the formation of a Yod from the simple quincunx in one chart to a sextile and/or quincunx in the other. This could indicate that those couples are willing and ready to work out their differences and learn to adjust to each other — the sextile makes them willing and gives them the opportunity to handle the necessary adjustments.

Note: the above is an excerpt from Carol's Astrology by Correspondence Intermediate course. Also covered in this lesson is the instruction of the synastry aspect grid and interpretation of the planetary contacts between both charts.

*Overloaded Houses: where four or more planets are contained within a house. This fascinating subject is covered in the Astrology by Correspondence Intermediate course.


© Carol Squires, 2018
kaza's web design