One very common use of astrology is to determine compatibility between people.
Another common use is to help people who are already in a relationship get along with each other.
The technique that is used to accomplish both of these goals is called synastry.
What is synastry and how does it work? Read on to find out.
What is Synastry?
Synasty is a comparison of the birth charts of two people to determine how they naturally interact with each other. This can help to assess compatibility.
It can also help to enhance positive interactions between people and minimize conflict and misunderstanding.
While the most common use of synastry is to assist with romantic relationships, it can also be used for any relationship. Friendships, working relationships, and parent/child relationships can all be enhanced by understanding this technique.
Most Sun Sign compatibility articles use basic synastry principles, but by their nature, they only address one part of the birth chart, the placement of the Sun.
Sun Signs do play a role in this technique, but there are also many other planets and chart points to consider.
A full synastry analysis will consider the entire chart of both people.
Many times, people who are very compatible by Sun Sign will have many problems that will become clear with a full synastry interpretation.
Likewise, people who are not compatible by Sun Sign may find hidden strengths in their relationship.
How to Read a Synastry Chart
Before learning synastry, it is important to understand at least the basics of natal chart interpretation. Once you do that, the basic method of determining compatibility through synastry is to:
- Know yourself and your partner
- Understand how your charts interact with each other using planets, houses, and aspects
Know Yourself and Your Partner
Before you can determine how you will relate to others, you need to understand yourself and your partner as individuals.
There are many things in your own birth chart and the chart of your partner that will give valuable information when it comes to relationships.
The website Astrology Season offers a free natal chart generator and report.
While your entire chart will play a role in your relationships, there are some considerations that specifically apply to synastry.
Read on to learn what these are.
One of the first things to consider when it comes to relationships is your elemental nature and that of your partner.
The elements in astrology are Fire, Earth, Air, and Water.
The simplest way to determine your dominant element is to count the number of personal planets and chart points that you have in each element.
Calculating Your Dominant Element
Different astrologers (and computerized chart generators) use different planets and chart points for this count.
Below are the planets and chart points that I use:
- Part of Fortune
I do not consider the Outer Planets, Uranus, Neptune, and Pluto in this analysis.
There are several reasons for this, but one of them is that all of these planets stay in the same sign for a very long time.
The element of each planet or chart point is determined by the zodiac sign it is in.
- Fire – Aries; Leo; Sagittarius
- Earth – Taurus; Virgo; Capricorn
- Air – Gemini; Libra; Aquarius
- Water – Cancer; Scorpio; Pisces
Once you determine the element of each planet or chart point, the element with the highest count is your dominant element.
The more planets/chart points you have in an element, the more dominant it is.
You may find that you have a tie or a relatively even amount of planets or chart points in each element. In this case, you can relate well to people of all elements.
You might find that you are lacking in an element. This is also significant. This can make it harder to relate to people of that elemental nature.
On the other hand, you might be drawn to this in others to make up for what you lack in yourself.
People with the same dominant element will understand each other very well and will tend to be highly compatible.
Those with Fire as the dominant element in their chart have a very high energy level.
They are passionate and adventurous. They want to be busy all of the time.
The most important thing for them in relationships is a feeling of excitement and chemistry.
They don’t mind conflict in relationships. Indeed, they are often aroused by a good fight.
Those without Fire in their charts will tend to lack energy and passion. They have a low tolerance for drama and can sometimes be seen as lazy.
Fire gets along well with Air. Fire has difficulty with Earth and Water.
Those who have Earth as the dominant element place a great deal of importance on the material side of life. They are practical and sensible.
For them, the romantic can not be separated from the pragmatic. They do not believe in whirlwind romances.
In relationships, security and financial well-being will take precedence.
Even so, they are very sensual and enjoy the physical pleasures of life.
Those without Earth in their chart will tend to have difficulty with practical matters. They have little interest in finances, which can lead to problems.
Earth gets along well with Water and has trouble with Fire and Air.
If Air is dominant in someone’s chart, they will have a strong intellectual curiosity and enjoy social situations. They enjoy meeting many different people.
For them, the most important thing in a relationship is communication.
They find intelligence to be sexy.
In general, they will not find anyone physically attractive who does not stimulate them intellectually.
Those without Air in their charts tend to have difficulty with things that are not concrete or tangible.
Air is compatible with Fire and has difficulty with Earth and Water.
Those whose dominant element is Water tend to be emotional and intuitive.
They feel their way through life, and often these feelings are quite accurate.
They can form very deep bonds with a partner. Trust and emotional connection are the most important things in a relationship.
They may not always express their feelings in words, but they always know if something is wrong in a relationship.
Those without Water in their charts can lack emotional depth and sympathy for the difficulties of others.
Water is compatible with Earth and has trouble with Fire and Air.
After determining the dominant element in your chart and that of your partner, it is important to look at the dominant mode.
While the Elements represent a person’s nature, the Modes represent the way that they respond to change and act in the world.
Use the same chart points that you did to determine your dominant element.
The modes are: Cardinal, Fixed, and Mutable
The modes of the zodiac signs are as follows:
- Cardinal – Aries; Cancer; Libra; Capricorn
- Fixed – Taurus; Leo; Scorpio; Aquarius
- Mutable – Gemini; Virgo; Sagittarius; Pisces
As a general rule, people who have the same dominant Mode have difficult relationships with each other.
Those whose dominant mode is Cardinal will enjoy taking on leadership positions. They enjoy being in control and want to change the world, or at least their surroundings.
Taking the initiative in anything comes easily to them.
People who lack Cardinal signs tend to have trouble getting started with projects or tasks.
When a relationship has two people whose dominant mode is Cardinal, they spend a lot of time vying for control.
People who have mostly Fixed signs in their chart are known for being persistent and disliking change. They can be extremely stubborn.
On the other hand, they always finish what they start.
People who lack Fixed signs have trouble following through with tasks or projects.
When both people in a relationship have mostly Fixed signs, they will both be set in their ways and have difficulty adjusting to each other.
People whose dominant mode is Mutable tend to be easy-going. They are able to adapt to change and do not need to be in control.
They are happy to go along with what someone else wants to do.
People who lack Mutable signs tend to lack flexibility and to resist changes that they did not initiate.
Unlike the other two modes, two people who have mostly Mutable signs can generally get along.
On the other hand, it is hard for them to accomplish anything together.
Planets in Synastry
Once you understand your general nature and that of your partner, it is important to consider the individual planets.
Planets represent the various parts of our personality and each of them has a particular function.
The most important planets in synastry are listed below.
Venus is the most important planet when it comes to relationships. This is the Planet of Love.
Often, Venus’ role is believed to only cover romantic love, but it rules all aspects of love. Friendship, love between a parent and child, and sacrificial love are all governed by Venus.
The placement of Venus will also determine what you want and desire in a partner as well as what you find physically attractive.
Venus is also important when it comes to long-term relationships. This planet determines how you show love and affection and how easy or hard it is to get along with others.
Venus functions the best in Taurus, Libra, and Pisces and is hampered in Aries, Scorpio, and Virgo.
The next most important planet when it comes to a synastry/compatibility analysis is Mars.
Mars governs how you go after what you want and how you take initiative. This planet shows how you assert yourself and how you handle conflict.
Even though Mars governs conflict, this planet also creates sexual chemistry, especially in connection with Venus.
Indeed, Venus/Mars contacts between two people is one of the indicators that a relationship will be a romance rather than a friendship.
Mars is at its best in Aries, Scorpio, and Capricorn and at its worst in Taurus, Libra, and Cancer.
Mercury governs communication, and this is essential to any relationship.
With good communication, even difficult relationships can survive. With bad communication, even the most compatible relationships can fail.
Mercury contacts between people will determine how well they will be able to work through problems and whether they feel like they can talk to each other.
Mercury is strongest in Gemini and Virgo and weakest in Sagittarius and Pisces.
The Sun and Moon
While the Sun and Moon play a large role in one’s natal chart, they play a slightly smaller one when it comes to synastry and compatibility. They are still very important, however.
Sun and Moon contacts between people will determine how much they feel they have in common and how well they understand each other on an intuitive basis.
Jupiter and Saturn
Jupiter and Saturn play a small but significant role in relationships.
On the other hand, Jupiter stays in the same sign for about a year, and Saturn spends around two and a half signs in one year.
Because of this, they become less relevant if you are with someone your own age.
If there is an age gap between you, even a relatively small one, these planets will come into play.
Jupiter governs a feeling of generosity and your ability to have fun together. Jupiter is also the planet that is involved in whether you will be able to forgive each other.
Saturn governs hardships and difficulties. This planet can put a damper on your feelings for each other.
On the other hand, strong Saturn contacts are often found in people who stay together for a long time. This is because Saturn gives the ability to persevere through problems.
The Outer Planets
The role of the Outer Planets, Uranus, Neptune, and Pluto, is variable. A lot will depend on the choices that both of you make.
Any impact that they have will usually be negative.
These planets move very slowly, so unless there is a very wide age gap between you, these planets will be in the same sign in both of your charts.
At most, they will be a sign apart.
Uranus represents the temptation towards hyper-individuality and independence.
This can cause unnecessary dissension in your relationship if you let it.
Neptune represents deception, delusion, and cloudiness of vision. It can be pleasant falling under Neptune’s spell, at least at first.
Sadly, though, doing so usually leads to disappointment and disillusionment.
Pluto signifies darkness and ugly, unpleasant things. More than that, it signifies an attraction to those things and the desire to dig them up.
Giving in to these temptations can cause all manner of difficulties in relationships.
Aspects in Synastry
In the previous section, I discussed connections between planets in the birth charts of two people.
These connections are known as aspects, and they are a key component of a synastry analysis.
The main aspects are the conjunction, the sextile, the square, the trine, and the opposition.
The easiest way to see these aspects is through the elements and modes described above.
Aspects are important in the birth charts of each individual separately and between their charts.
It is very common for there to be strong connections with people who have planets that trigger important aspects in your own chart.
The most powerful aspect is the conjunction (0 degrees). This is when planets are together, usually in the same sign.
This aspect can be easy or difficult depending on the planets involved.
In general, conjunctions with Venus and Jupiter are beneficial. Conjunctions with Mars and Saturn tend to be difficult.
When in conjunction, Mercury tends to blend with the other planet.
Conjunctions with and between the Luminaries, the Sun and Moon, are powerful but complicated. Much will depend on the zodiac sign involved.
Conjunctions with the Outer Planets represent temptations that can lead to disaster if you succumb to them.
The sextile (60 degrees) is a pleasant aspect that tends to energize and excite.
Signs that sextile are are two signs apart.
They are of complementary elements (Fire/Air or Earth/Water), but they have different modes.
In general, planets that are sextile are friendly to one another. They like each other and act as allies. In most cases, sextiles are positive aspects.
The situation is complicated, however, when it comes to the malefics, Mars and Saturn, and to the Outer Planets, particularly when they sextile the Luminaries, the Sun or Moon.
They are still friendly, but they are not necessarily helpful. They can be compared with friends who are a bad influence.
The square (90 degrees) is a tense aspect. The general feeling of a square is of friction and annoyance.
Signs that are square are 3 signs apart.
Signs that are square have the same mode, Cardinal, Fixed, or Mutable, but are of incompatible elements, i.e. Fire and Water.
Planets that are square continually rub each other the wrong way.
That being said, in romantic relationships, the tension from squares can easily turn into sexual chemistry.
A common aspect between people who find each other irresistibly attractive is a square between one person’s Mars and the other person’s Venus.
Also, squares with the benefics, Venus and Jupiter, tend to be much easier than those with other planets.
This is because Venus and Jupiter, by their very nature, want to be helpful. They will not give as much help as they would with an easier aspect, but they will also avoid doing any harm.
The trine (120 degrees) is a lovely aspect. Trines bring harmony and understanding. Signs that are trine have the same element.
In the chart, they are 4 signs apart.
In synastry, trines between the charts of two people will show areas of complete harmony and understanding.
This is where people can complete each other’s sentences, and they feel calm and safe with each other.
In romantic relationships, trines are very helpful.
On other other hand, if two people have too many trines with no squares, they may lack sexual chemistry. Their relationship can seem more like a close friendship than a romance.
Trines are usually helpful even with the malefics, Mars and Saturn.
Trines with Mars tend to give strength and courage, and trines with Saturn give patience, stability, and perseverance.
Oppositions (180 degrees) in a birth chart are tough. They mean exactly what their name implies, the planets oppose one another.
In synastry, however, the situation is a bit more complicated.
When learning astrology, it is very helpful to learn and memorize the opposite sign pairs. These are:
Opposite signs have the same mode, but are of complementary elements (Fire/Air or Earth/Water).
Oppositions are common in relationships, particularly marriages and long-term partnerships.
This is because they bring balance. The other person is strong where you are weak, and vice versa.
Even so, oppositions with the malefics, Mars or Saturn, or with the Outers can be extremely difficult and trying.
In this section, the aspects were described by sign alone.
If you are a beginner, spotting aspects by sign will give you plenty of usuable information.
Many astrologers prefer to be more precise, however, and count aspects by the degree, leaving an allowable margin of error. This margin is known as an orb.
Different branches of astrology determine orbs differently, and individual astrologers will vary in the orbs that they use.
When measuring aspects using exact degrees and orbs, sometimes a chart will have what is known as a “cross-sign” aspect. That is when planets are in aspect by degree, but not by sign.
An example of this would be 29 degrees of Aries and 1 degree of Taurus. Different astrologers treat cross-sign aspects differently.
The most important thing to know as a beginner, however, is that the closer an aspect is by degree, the stronger it will be.
It is fine to ignore cross-sign aspects until you are more experienced and have thought through how you want to deal with them.
Houses in Synastry
Houses in a birth chart signify topics in our lives. Each house governs a general area of influence.
In synastry, it is important to know what houses the planets in the other person’s chart touch to determine what part of your life they will impact.
The Relationship Path (1st, 11th, 5th, 7th)
The most important houses when it comes to romantic relationships are the 1st, 11th, 5th, and 7th.
These houses form a path that tells the iconic story of how relationships progress.
All relationships start off as 1st House relationships.
This is the part that you show to people you do not know and how you act with someone you have just met.
This house also determines whether you or the other person will decide to meet again.
The Ascendant is a special chart point that is a part of your First House. This is the place that was rising in the East at your first breath.
The Ascendant forms aspects just like the planets do, and it relates to your body, your appearance, and how you present yourself in the world.
The 11th House governs friendships. Many romantic relationships start off as friends, and some never go beyond friendship.
In the context of relationships, the 5th House governs dating and romantic relationships.
The 5th House is always the opposite of the 11th House, and for most people, there is a marked difference between friendships and romantic partners.
The 7th House is the house that governs marriage and long-term partnerships.
This house is always the opposite of the 1st House. You can look to your 7th House to determine the qualities of your ideal mate.
The other houses also play a role in relationships, but they usually come into play once a long-term relationship is forged and you decide to spend your lives together.
Analyzing these houses can give an indication of your strengths and challenges in living together.
This is the house of money and possessions.
Issues concerning 2nd House matters can make or break many marriages and long-term partnerships.
This house governs communication, siblings, and short trips. Communication is an important part of any relationship.
This house can also be a trap for romantic relationships if one person starts to see the other as a brother or a sister.
This is the house of the home. It governs domestic matters.
It also governs matters related to your parents, your lineage, and your traditions.
This house governs matters related to illnesses. It also governs the day-to-day chores necessary to run a household.
Your job can also fall under the 6th House, particularly if it is not a career or vocation, but simply a way to pay the bills.
The 8th House represents some of the biggest challenges to marriage and long-term partnerships. This house governs matters such as death and hidden dark secrets.
It also is the house of “other people’s money,” and governs your joint finances.
This house will governs your faith or religion. It also governs higher education and foreign travel.
The 10th House governs your public persona and your reputation.
The 10th House is always the opposite of the 4th, and the 4th/10th axis will show how well you are able to balance your home and your career.
While the 7th House is the House of Marriage, wedding ceremonies are 10th House matters.
The Midheaven is the chart point that represents the place that was the highest in the sky when you were born.
This point will form aspects just like a planet does, and its meaning is intertwined with the 10th House.
This house has complicated significations, but in the context of a relationship, this is your blind spot.
These are the things that your partner will see in you that you cannot see in yourself.
Putting It All Together
A synastry compatibility analysis is complex and involves juggling a lot of information. Some of the information is confusing and may even be contradictory.
This matches life. Relationships are complex as well.
If you are just starting out, take your time. Look at a few considerations and see if they help you understand your relationship better.
If something does not make sense, put it to the side. It may make more sense when you look at other considerations in the synastry analysis. You may also find that there are other things that counterbalance or even contradict it.
Remember that the purpose of a synastry analysis is to help you and your partner understand each other better.
This will make it easier to make decisions about your relationship and will give you guidance to get through rough patches.
Don’t expect to understand everything right away. Just as your relationship, your synastry chart will unfold over time.