Synastry: Relationships in Astrology

Synastry consists of comparing the birth charts of two people to assess the compatibility between them, in any area of their personalities and lifestyles.

Synastry consists of comparing the birth charts of two people to assess the compatibility between them, in any area of their personalities and lifestyles. The synastry report is a tool that allows you to reevaluate relationships, if you have difficulties, or deepen the relationship. In this article, we talk about what synastry is and how astrological elements contribute to its definition and analysis.

How Does Synastry Work?

There are specific areas in the birth chart that show how people react in a relationship. This is not limited to emotional relationships, it also encompasses friendship, the professional field or the relationship between parents and children. If you are thinking of opening a business with another person, for example, synastry helps in the study of the personality traits of both, which will result in a greater harmony of the relationship.

The starting point for synastry is the analysis of the birth chart . When trying to study a particular type of relationship, it is necessary to analyze both letters. Otherwise, the report is limited to the characteristics of one part of the equation, which makes it impossible to analyze the result of the interaction between the two personalities.

On the other hand, the complete analysis of synastry implies knowledge of the Ascendant and the Midheaven . When the date of birth is unknown or uncertain, it is not possible to analyze these important data in the characterization of the astrological personality, and the synastry report remains incomplete. Similarly, when there is uncertainty about the time of birth, there may also be doubts about the moon sign, if the Moon has changed the signs at the time of birth.

When looking for information about the compatibility between signs on a website or in a magazine, the analysis you can find is inevitably incomplete and general. As we have seen, the synastry report can only be done in the presence of the birth certificates of the people involved. In most cases, like here in AstroMundus, the compatibility analysis is done based on the Elements of each of the signs .

Although the signs have profiles that allow us to deduce whether they are more or less compatible with others, only through the astral diagram is it possible to make a realistic interpretation and draw true conclusions.

It is also worth noting that relationships can be more or less fluid depending on the assumptions and personal characteristics (such as communication skills, empathy, sympathy, understanding, tolerance, willingness to negotiate a consensus, among others), which constitutes the astrological personality in part.

The synastry report involves the analysis of the various points present in the chart: the positioning of the planets, the aspects that form between them, the Houses , the polarities, the elements , among others.

The Astrological Elements in the Synastry Report

1. The Planets

When comparing two astrological charts with the aim of producing a synastry report, the analysis of the position of the stars and the relationships between them is a fundamental point. The planets and the relationships they establish with each other define an astrological profile that can then be compared to someone else’s.

The Ascendant and the Sun Sign

The Ascendant and the Sun represent our personality. The analysis of the two elements allows evaluating temperament and tolerance, which are essential factors in any type of relationship.


The Moon represents our instincts, reactions and responses to all situations. In synastry, it shows how the person interacts with the partner, which gives clues about how they react to each other in the relationship.


Mercury represents our mind, intellect and the power of communication. In synastry, it reveals the ability to communicate the thoughts, ideas and feelings of each part.


In Astrology, Venus represents love, affection and material goods. These aspects are interrelated, particularly in a synastry analysis. The possession and exchange of material goods can be seen from the analysis of the positioning of this planet.


Mars represents our physical energy, the drive to move forward in the relationship, and sexual desire in love relationships. Mars in evidence can dominate the sexual side of an emotional relationship.


This planet symbolizes expansion. In synastry analysis, Jupiter represents the way in which one partner will help open up the other’s life and the element of challenge in the relationship. This planet also shows enthusiasm and courage in developing the relationship.


Saturn means limitation, control and stability. Your influence can be particularly intense if you create a powerful Aspect with the Sun, the Ascendant, or with the personal planets of the other person under analysis.


Uranus symbolizes breakup and change, and can be present at the beginning or end of a relationship. It can be a source of tension or attraction, depending on your position and interactions on the chart. Like Neptune and Pluto, Uranus stays in each sign for a long time and its influence is likely to be felt on both charts.


Romantic and mystical planet, the influence of Neptune can be the cause of great happiness, but also of disappointment, unbalancing a relationship. Like Uranus and Pluto, Neptune stays in each sign for a long time and its influence is likely to be felt on both charts.


This planet helps us solve psychological problems. When present in the letter, it suggests that the person is willing to solve their problems and invest in the relationship. However, it can also indicate a blockage or difficulty moving forward in relationships. Like Uranus and Neptune, Pluto stays in each sign for a long time and its influence is likely to be felt on both charts.

2. The Astrological Houses

House 7

House 7 (House of marriage or House of declared enemies). Here, “marriage” is understood as any type of relationship that involves a commitment over time, such as marriage, business relationships, partnerships, contracts, negotiations, diplomacy, agreements, and declared enemies. This House is the most relevant in the analysis of synastry. The sign at the top of this House is a good indication, as well as the influence of the planet (s) positioned there. If there is no planet in this House, the analysis is carried out by observing the sign opposite the Ascendant. House 7 refers to the needs and requirements of the person with respect to partners.

House 2

House 2 is traditionally described as the House of “values, possessions, money and resources”. It also gives us a mission to develop a stronger sense of our worth and qualities. In this sense, it influences the attitude of each couple regarding the way they express their emotions and in the sexual sphere. It also provides information on trade associations.

House 4

House 4 offers us the challenge of putting all the pieces together and integrating them into our own value system, which will become the center of our personality, our unique identity. It is the House of the family, the home and the domestic affairs. It shows how much we want to be stable, it reflects our attitude towards family life and our feelings regarding motherhood / fatherhood.

House 5

House 5 highlights our need to be recognized (by our partner, family, in the workplace, in society), to make a difference in someone’s life. This is also the home of romance and emotional risks. Will the relationship evolve? Is one partner more involved than the other? Will the romance last? These are some of the themes of this House. This is also the House of creativity, which can be related to our attitude towards children.

House 8

The 8th House represents the most intimate relationships and the emotional transformations that result from this interaction. It is the House where personal crises occur and where the most profound changes in personality occur. In this sense, it influences the attitude of each couple regarding the way they express their emotions and in the sexual sphere. It also provides information on trade associations.

3. The Polarities

The characteristics of each of us influence the type of relationships we seek and how we behave in the relationships we build throughout our lives.

An extroverted personality (of positive polarity or Yang in Chinese Astrology , which characterizes the signs of Fire and Air ) can be successful in a relationship with an introverted personality (of negative polarity or Yin, and that characterizes the signs of Water and Earth ). .

Remember that relationships are influenced by multiple variables, astrological being one of them. Will, commitment, and free choice really affect how relationships may or may not progress favorably . Any relationship, regardless of the influence of the astral elements, can work as long as there is the will in both parties for it to happen.