Synastry aspects are perhaps the most important factors in horoscope matching. Use this free synastry aspects guide as a starting point in compatibility reading. Aspects with the planets, sun, moon, ascendant and midheaven are briefly interpreted. Don’t miss the birth chart compatibility guide for a quick overview of compYou might also want to check out how to do synastry with a step-by-step walkthrough.

Most Important Aspects in Synastry

To be able to make a meaningful analysis of two charts, focus on those aspects that have the strongest influence.  Some of the most important synastry aspects are:

  • Sun and moon aspects (any combination)
  • Ruling planet aspects (ruler of the ascendant)
  • Aspects with the angles (ascendant, midheaven and their opposite angles)
  • Aspects with Venus
  • Aspects with Saturn to the luminaries or an important planet like Venus
  • Aspects with the ruling planet
  • Aspects between the angles

It’s a common mistake to over-emphasize unimportant or weak aspects.  Avoid this. Likewise, don’t make too big a deal out of even strong aspects, lest you alarm the subject(s) unnecessarily.

Synastry Aspects As Transits

When a mother gives birth to her child, the birth chart of that child is the same as the transits to the mother’s chart on that day.  Think of synastry aspects as like that.  Synastry aspects are like long-lasting — even permanent — transits to one’s natal chart.  They cause change in our lives, awaken certain potential in us and reveal sides of ourselves that might otherwise remain hidden.

This is meant as a general guide only. For a clear and practical guide to horoscope matching, see Synastry: Understanding the Astrology of Relationships by the South African astrologer Rod Suskin.  Also good reading is Parkers’ Astrology by Derek and Julia Parker. The latter is a comprehensive introduction to natal astrology with sections devoted to synastry. The interpretations below are based in part on the Parkers’ treatment, along with personal experience. Look for the revised and updated edition.

Ascendant Synastry Aspects

The ascendant is not a planet; it is the first degree of the first house. When one partner’s ascendant makes an aspect to a planet in the other partner’s chart, it does not generate the same energy or tension that a planet-to-planet aspect does. But it is always important. What is more, aspects to the ascendant cannot be separated from the house the aspecting planet is in. For example, a Partner A’s Uranus in a square to Partner B’s ascendant will have a different effect depending on whether it is from around the midheaven or medium coeli (tenth to ninth house) or the immum coeli (fourth house).

Ascendant-Ascendant. Similarity of personalities, vitality and approach to life.  Peace and contentment, or strong attraction or rivalry.

Ascendant to Midheaven. Shared goals and career objectives. Rivals or teammates.

Ascendant to Sun. Intellectual and physical compatibility. The sun person energizes the ASC person. Hard aspects strengthen the sun person’s influence in key areas of the ASC person’s life.

Ascendant to Moon. Familiarity and a sense of security. Both partners feel comfortable in each other’s presence. If negative: emotional clashes.

Ascendant-Mercury. Excellent communication. Mercury opens the ASC person to change and new ideas.

Ascendant to Venus. Mutual attraction, love and friendliness. Comfort and luxury. Fond of good times together.

Ascendant to Mars. Strong motivation. Heightened sexual energy. Rivalry and quarrels. The negative aspects cause disruption in the house involved.

Ascendant to Jupiter. Drama, humor and confidence. Blowing things out of proportion or taking foolish risks. Jupiter boosts the ASC person’s faith in him- or herself.

Ascendant to Saturn. A mature, committed partnership. Stability and structure. If negative, Saturn can severely limit ASC’s self-expression. Also restrictions in the house occupied by Saturn in the ASC person’s chart.

Ascendant to Uranus. A dynamic, earth-shaking influence. Uranus knocks ASC off his or her feet, but craves freedom. An exciting but short-lived affair, but look to other aspects.

Ascendant to Neptune. Deception or confusion between the partners. One puts the other on a pedestal. Romance and over-idealism.

Ascendant to Pluto. Compulsive, controlling behavior. Pluto is jealous, domineering and perhaps manipulative.

Midheaven Synastry Aspects

These aspects affect the career, ambition and public life of the person whose midheaven is aspected by the other person’s planet(s). Midheaven inter-aspects are especially important for business relationships. But they are important for all kinds of relationships. If you are a very career-oriented person, consider these aspects to see how your partner can impact your work and goals.  Midheaven aspects affect our lives beyond career as well. The MC shows what one aspires to.  When your partner aspects your midheaven, it has an effect on your aspirations and sense of direction in life.

Midheaven to Sun. Shared ambitions and career objectives. The sun person supports the MC person in their pursuit of their goals – or opposes it. The sun’s influence in its house position is strengthened.

Midheaven to Moon. Similar aspirations. The moon person is attached to the MC person’s work and public life. May draw attention to the couple or bring their private affairs out into the open.

Midheaven to Mercury. Helpful and active.  May encourage frequent change of direction in work and relationships.

Midheaven to Venus. Good for business and public relations. The Venus person can help enhance the MC person’s public image. Can attract good friends.

Midheaven to Mars. Leadership. Mars will encourage the MC person to achieve career goals – or stand in the way.

Midheaven to Jupiter. Ambition. Jupiter helps the MC person realize his or her career goals. May bring positive influences.

Midheaven to Saturn. Dedication to hard work. Saturn makes the partner work hard for everything. Success comes to the MC person through persistence and determination. Saturn gives solid support.

Midheaven to Uranus. A radical change in career objectives. Uranus can open new doors of opportunity that MC never thought of as possible. But Uranus’ erratic behavior can cause problems for MC.

Midheaven to Neptune. Idealism. Neptune may bring uncertainty to MC, causing the latter to question his or her purpose in life. Good for spiritually minded people although there is danger of deception and lack of focus.

Midheaven to Pluto. Shared love of power and control. These two will plan for world conquest. There is danger of trying to manipulate each other and others to get them out of the way.

Sun Synastry Aspects

Synastry aspects with the sun affect the sun person’s sense of well-being.  Easy or harmonious aspects make one feel content and fulfilled in the relationship; whereas hard aspects present conflicts that make it difficult to realize that well-being.

Sun to Sun. Similar goals and aspirations. A sense of well-being. Positive reinforcement. Otherwise rivals.

Sun to Moon. All Sun and Moon synastry aspects are important. Exchange of yin and yang energies. Mutual attraction. Moon depends on sun for strength and motivation. Sun thrives on moon’s attention. If negative: a clash of the rational and the emotional.

Sun to Mercury. Intellectual rapport. Good for communication in all kinds of relationships. If negative: debate and disagreements.

Sun to Venus. Mutual love, affection and appreciation. Easygoing spirit. Venus’ social graces and creative gifts reinforce the sun’s well-being.

Sun to Mars. A Sun and Mars synastry means ego support or conflict, depending on the aspects. Powerfully ambitious and a hardworking tandem. Sun and Mars energize each other, or if negative: always at each other’s throats.

Sun to Jupiter. Boost in self-confidence for both partners. Jupiter encourages sun to be his or her best self. Much good humor.

Sun to Saturn. A serious, perhaps lifelong commitment.  Saturn creates structure and permanence to support the sun’s hopes and aspirations. But if negative, Saturn can make life a prison for the sun person. An ambitious couple.

Sun to Uranus. A dynamic twist. Uranus challenges the sun to look at life and self in new ways. New opportunities and sudden changes. Freedom and unpredictability. Look to other aspects for stability.

Sun to Neptune. Spirituality and idealism. Neptune can either inspire the sun person or cause self-doubt and confusion about one’s true motives. Deception – whether deliberate or unwitting – is a strong possibility. Openness and honesty a must.

Sun to Pluto. Obsession and jealousy. There can be a powerful attraction and a strong drive to succeed together. But Pluto can be controlling and compulsive. If positive: has the ability to make great changes in their lives and others.’

Moon Synastry Aspects

Aspects to the moon affect us deeply, especially in personal relationships. Because the moon governs emotions, lunar inter-aspects affect how we feel about ourselves in a relationship. Easy aspects make both partners feel comfortable about themselves and each other. Hard aspects can make you feel rejected or bad about yourself, but they can also act as a restraint or anchor for people who tend to go to extremes.

Moon to Moon. Similar moods and temperaments. Can support each other through emotional ups and downs, or else counter each other’s instincts.

Moon to Mercury. Emotional and intellectual rapport. Intuitive understanding of each other. If negative: petty arguments.

Moon to Venus. Love and friendship. Comfort and familiarity. Can be demonstrative depending on the zodiac signs.

Moon to Mars. Moon and Mars in synastry is emotional strength or domestic quarrels. Increased passion and attachment. Mars brings vigor to the moon or causes restlessness and anger.

Moon to Jupiter. Emotional well-being and support. Can exaggerate matters. Because the moon is subjective and Jupiter is apt to dramatize, these aspects can make it hard for a couple to put things into the right perspective.

Moon to Saturn. Emotional stability and security if positive. If negative: loneliness and feelings of rejection on the part of the moon. Saturn may think moon is too emotional. Inability to show true feelings. Frustration.

Moon to Uranus. Restlessness and excitement. Difficulty relaxing. Emotional detachment. Moon is baffled by Uranus’ ability to look at things differently, objectively.

Moon to Neptune. Both partners idealize each other, perhaps to the point that the relationship stays platonic. Selflessness. Perhaps a telepathic connection. If negative: deception or delusion.

Moon to Pluto. A strong emotional bond that can be hard to get out of. Can be stifling for the moon person. Emotional blockage.

Mercury Synastry Aspects

Mercury deals with communication, which is undeniably important in all kinds of relationships. Aspects with Mercury affect how you and your partner share thoughts and feelings with each other. A strong Mercury helps you open up and speak your mind to each other. It also helps you develop and realize your plans as a couple.

Mercury to Mercury. A pair of chatterboxes when together. Many shared interests. Talking, writing and other mercurial activities have above-average importance. An intellectual couple.

Mercury to Venus. Good for all manner of communication and social activities. Great friends. A creative tandem. Both partners benefit by an exchange of thoughts and opinions.

Mercury to Mars. Increased mental and verbal activity. Argumentative.  One is a planner and the other is a doer. An active couple.

Mercury to Jupiter. Two great minds united. A balance between small and great. Jupiter focus on the big picture, Mercury tackles the details.

Mercury to Saturn. A Mercury and Saturn synastry shows solid mental connection if positive. Mercury helps Saturn express him- or herself better. Saturn makes sure Mercury’s ideas will stand the test of time. But if negative, Saturn can dampen the spirit and creativity of Mercury.

Mercury to Uranus. Openness to the strange and unusual. Much can be learned from each other. Uranus can be impatient with Mercury.

Mercury to Neptune. An intuitive, perhaps telepathic connection. Neptune can tune in to what Mercury is thinking. But Neptune can confuse Mercury.

Mercury to Pluto. These aspects encourage secretiveness. Pluto controls the outflow of thoughts and ideas from Mercury, or else help transform their ideas into something great. Mercury can pick up Pluto’s inner thoughts and motives.

Venus Synastry Aspects

Aspects to Venus reveal how well a person can express love and affection. Harmonious aspects to Venus help you show the more pleasant side of your personality. Because Venus is also the planet of entertainment and leisure, its inter-aspects affect how you can give and receive pleasure in the relationship.

Venus to Venus. Strong emotional bond if positive. Can be friends or lovers. Each person reinforces positive feeling in the other. Encourages open display of affection. If negative: can inhibit the expression of love.

Venus to Mars. Strong sexual attraction and compatibility. Venus is the tender side of love, Mars is the passionate and forceful one.  If Mars is too strong, the Venus person may be overwhelmed. All aspects are important for romance and marriage.

Venus to Jupiter. Love of luxury and pleasure. Generous toward each other. Can over-indulge each other’s whims.

Venus to Saturn. Restrained affections. These two planets do not get along easily. Venus is warm and kind, Saturn is cold and detached. Prudent with money, responsible and dutiful toward each other if positive. If negative, Saturn suppresses Venus’ fun-loving and affectionate nature. Possible disagreements over money and material issues.

Venus to Uranus. An exciting love affair. But without aspects that show permanence, it may be short-lived or unstable. Once the novelty wears off, Uranus wants his or her freedom back. May have a taste for the unusual as a couple.

Venus to Neptune. A Venus and Neptune synastry aspect is romance fit for a novel. Both partners idealize each other and their relationship. But disillusionment can set in once the truth comes out.

Venus to Pluto. Strong emotional ties. Pluto creates an intense, passionate atmosphere around Venus, who may either get turned on or feel suffocated. Sexual encounters can be transforming.

Mars Synastry Aspects

Aspects to Mars energize a relationship. Hard aspects mean you need to overcome your differences in order to use your energies for your benefit as a couple; otherwise it can be destructive for you two. The softer aspects are easier to deal with and allow the Mars person to support the other person’s endeavors or needs (as shown by the other planet).

Mars to Mars. A highly charged partnership. If positive: the partners drive each other to succeed. If negative: lots of disagreements and tempers flaring. An active sex life where the partners try to outdo each other.

Mars-Jupiter. Confidence. Jupiter encourages Mars to take positive action. Mars has the ability and drive to realize Jupiter’s ideals. Can be foolhardy and careless.

Mars to Saturn. Disciplined action. Can be constructive and steadily productive. Together they work hard to build things that will last. If negative, Saturn will frustrate Mars, while Saturn sees Mars as a rule-breaker.””

Mars to Uranus. Excitement. This combination stimulates both partners to try new things. Never static for too long. Together they are not afraid to be different from others. Uranus rebels against the willful Mars. Angry outbursts.

Mars to Neptune. Deceptiveness in action. Neptune wants to take the easy way out of things, while Mars wants to tackle them head on. Good for creative work and romance but dangerous for business and relationships.

Mars to Pluto. Compulsive action. When positive, the couple have the power to make sweeping changes in their lives. Their actions will have far-reaching consequences for better or worse. Negatively, one tries to control the other. A power struggle.

Jupiter Synastry Aspects

These aspects influence your views on yourself, the relationship and life. Jupiter will tend to dramatize or exaggerate the influences of the other planet. It brings confidence, faith and benevolence.

Jupiter to Jupiter. Sense of humor, optimism and tolerance. None of these aspects are hard. But they can make the partners too optimistic sometimes. Good for intellectual and philosophically minded people.

Jupiter to Saturn. A blending of opposite impulses. Jupiter is the optimist, Saturn is the pessimist. One partner’s exuberance and self-confidence are balanced by the other’s caution. A safeguard for people who are apt to go to extremes.

Jupiter to Uranus. Brews new ideas and challenges.  One encourages the other to be open-minded and to see different points of view.

Jupiter to Neptune. Idealistic and spiritual. Encourages generosity and helpfulness in each other. Good for charity, religious activities, astrology and mystical practices. Negatively, it causes delusion and blind optimism and trust.

Jupiter to Pluto. Cunning and the ability to formulate plans together.  The ability to see both the light and dark sides of things. Good for business and work. Negatively, Pluto may hinder Jupiter.

Saturn Synastry Aspects

Saturn has a negative reputation in astrology because its aspects are often inhibiting. In relationships, Saturn aspects bring stability, commitment and a sense of responsibility. It also denotes fear and a tendency to stand in the way of the nature shown by the other planet.

Saturn to Uranus. A struggle for control. The Uranus person wants freedom while the Saturn person wants to restrict it. Look to the houses involved. If positive: there is balance between the old and the new, change and habit.

Saturn to Neptune. A need to be secure in beliefs and ideals. If positive, Saturn helps Neptune to realize its dreams and inspirations. If negative: Saturn is skeptical toward Neptune, causing worry and lack of self-confidence.

Saturn to Pluto. A power struggle. Both partners are eager for control of the houses involved. Pluto threatens to destroy what Saturn builds, if negative.

See also which planets show compatibility and how to check horoscope matching between partners.

More on Horoscope Matching and Synastry Aspects

For astrology books that deal specifically with the topic of synastry, I refer you to Rod Suskin’s Synastry.

Also see Do It Yourself Relationship Astrology.  It’s not a spectacular work but it is notable for its lengthy treatment of synastry aspects and zodiac sign matching.  It’s a good read so long as you don’t believe everything you find in it, and you keep in mind it lacks synthesis. The author does make an attempt to make it as easy as a DIY as possible. Even fairly experienced hobbyists will find it useful when they get stuck with something.

Want to study aspects in-depth?  You might want to check out Aspects in Astrology: Understanding Relationships in the Horoscope by British astrologer Sue Tompkins. This book is packed with information and insights about the aspects in natal charts. If we consider that, to a large extent, synastry is the study of aspects between two charts, we can see how relevant such a book really is to the astrology of relationships. And Tompkins’ book is one of the best out there.

Another good book on aspects is Dynamics of Aspect Analysis: New Perceptions in Astrology by Bill Tierney.  This volume discusses various topics that are not dealt with in many books. You might not agree with everything in it, but there is a lot of useful information about aspect patterns, retrogade planets and more.