Almost every best and worst synastry aspect list is ranked by how the contact feels. Trines at the top. Squares at the bottom. Saturn somewhere near the fire exit.
The astrologers who wrote the source material do not rank them that way. They rank by how much weight a contact carries, which is a completely different question, and it produces a list that is going to irritate somebody.
Start with the part nobody puts in the listicle. March and McEvers say that without some strong Saturn contacts, any union rarely lasts. They call Saturn contacts among the most binding in any serious commitment. Then, on trines and sextiles, the aspects every list crowns, they say those show harmony but not necessarily longevity.
Read that twice. The contacts the internet tells you to dread are the ones the literature names as the requirement for duration. The contacts everyone hopes for are the ones described as lovely and non-committal. Both statements are in print, from the same authors, in the same book.
Here is what the sources actually say, in the order they say to read it.
Read The Two Charts First
This is not preamble. It is rule one in two separate books.
Arroyo opens his synastry outline with it. The individual chart comes first, and his reason is blunt: a person may be compatible with nobody, and no comparison means anything until you know that. Steven and Jodie Forrest arrive at the same rule independently in Skymates, saying the process starts with a long hard look at the two birth charts, separately.
So before you compare anything, read each person's capacity for relationship: the seventh house, the aspects to the Sun and the Moon, and the sign and aspects of Venus. That is the full list, and it is worked through in capacity for relationship in a birth chart.
Skipping this is the single most common way a synastry reading goes wrong. Two charts can show beautiful contacts between two people, one of whom is not currently able to be in a relationship, and the contacts will not tell you that. The individual chart will.
What Actually Makes A Contact Strong
Four factors, and aspect type is only one of them.
1. Tightness. Arroyo singles out interaspects within about 2 degrees, and his reason is mechanical rather than aesthetic: a contact that tight will be simultaneously activated by a single transit in both charts. Both people get hit at once. He calls this shared experience. Contacts within about 4 degrees are the ones he says to look at first.
Forrest treats orb differently, as a strength dial rather than a cutoff. An eleven degree sextile is still real, just quieter. Nothing gets excluded, things get turned down.
2. Whether a personal planet or angle is involved. This is Arroyo's own emphasis. Any close interaspect involving at least one personal planet, or the Ascendant or Descendant, is most important. Burk goes further and does not count the outer planets at all in a comparison.
The practical version: Pluto square Pluto between two people born in the same decade is not a fact about their relationship. It is a fact about their birth years.
3. Repetition. A contact that appears in both directions is what Arroyo calls a major type of energy exchange, and what most people know as a double whammy. Her Venus to his Mars and his Venus to her Mars is structurally different from either one on its own.
4. Concentration. Where one planet collects a large number of contacts, Arroyo says that planet's tone colours the entire relationship. If eight of the eleven contacts in a comparison touch one person's Saturn, the relationship has a Saturn flavour regardless of what else is in the grid.
The Contacts That Carry The Most Weight
Sun And Moon Between The Two Charts
March and McEvers call these among the most vital links in synastry, and their rule on aspect type is worth quoting for how flatly it contradicts the usual ranking: any aspect is better than none.
The conjunction they call the most fulfilling and the classic bond in a union. But an opposition implies attraction, and a square also draws, adding a contest over authority. What is not good is the absence of any Sun and Moon contact at all.
Saturn Contacts, Especially To The Personal Planets
This is where the standard best and worst list goes most badly wrong.
March and McEvers: without some strong Saturn contacts, any union rarely lasts. They call Saturn contacts among the most binding in any serious commitment, and say all Saturn contacts are noteworthy, especially those to the personal planets.
Saturn contacts get listed as the worst aspects in synastry constantly, and they are the ones the literature names as the requirement for durability. Both things are true at the same time. Saturn contacts are heavy, they involve obligation and limitation, and they are what turns a relationship into a structure rather than an episode.
If you are looking at a comparison with no Saturn in it anywhere, that is information.
Moon And Venus
March and McEvers: the most amicable lunar interrelation is to Venus. This is the contact most associated with ordinary daily ease, which is a different thing from intensity and a different thing again from durability.
Angle And Ruler Conjunctions
Arroyo gives a specific and narrow rule here. A conjunction from either person's Ascendant, Descendant, or first or seventh house ruler to one of the other's planets sets the overall long term tone.
He names the conjunction and no other aspect, which is unusual for him, and the narrowness is worth respecting rather than quietly widening to all aspects because it would give you more to say.
Arroyo's Named Pairs
After the close contacts, he says to read elemental harmony and specifically these pairings: Sun to Sun, Moon to Moon, Mercury to Mercury, Venus to Venus, Mars to Mars, Venus to Mars, Venus to Moon, and Sun to Mars.
So What Are The Worst Ones
The honest answer is that the sources are far less interested in this question than the internet is, and the reason is that they are not sorting by comfort in the first place.
What the material actually supports:
Hard aspects are not the problem. Squares and oppositions between charts are contacts. March and McEvers describe both as producing attraction. A square adds a contest over authority, which is a describable dynamic, not a defect.
Easy aspects are not the reward. Their line is direct: trines and sextiles show harmony but not necessarily longevity. A comparison built entirely on trines can describe two people who get along beautifully and never quite commit to anything.
Outer planet contacts to personal planets are the ones to handle carefully, and the caution is about weight rather than harm. Arroyo treats houses receiving the outer three planets as not usually important, with three exceptions: a close conjunction to a planet, a close conjunction to an angle, or a large age gap between the two people. When one of those fires, the contact is not merely admitted. By his own construction it is one worth reading closely.
The genuinely bad sign is absence. No Sun or Moon contact, no Saturn anywhere, nothing tight enough to be activated together. That describes a comparison where two charts are simply not talking to each other, and it is a more meaningful negative finding than any individual hard aspect you could name.
The Order To Read Them In
Put the source rules together and you get this sequence.
- Each chart alone. Capacity for relationship, from the seventh house, the aspects to the Sun and Moon, and Venus. Then emotional and sexual needs from Mars, Venus and the Moon, against the chart's elemental balance.
- The close interaspects. Within about 4 degrees first, then flag anything within 2 degrees as shared experience.
- Contacts involving a personal planet or an angle. These outrank contacts between two slow planets regardless of how tight the slow ones are.
- Repetitions and concentrations. Anything appearing in both directions, and any planet collecting an unusual number of contacts.
- The house overlays. Which area of each person's life the other's planets land in. See synastry house overlays.
- Elemental and modal texture. See element compatibility and cardinal, fixed and mutable.
Notice that the famous aspect list arrives at step three of six, and that three of those six steps happen before you get to it. Most of the internet starts at step three and stops there.
Why We Do Not Publish A Compatibility Score
Because every one of the rules above is a weighting judgement made by a named author, several of those authors disagree with each other, and adding them into a single number hides all of it.
Arroyo and Forrest disagree about whether orb is a cutoff or a dial. Burk excludes the outer planets entirely and Arroyo admits them under three specific conditions. Those are real disagreements between serious practitioners, and a percentage on a screen would quietly resolve them without telling you it had done so, or on whose authority.
A reading that shows you which contacts are strong, why they are strong, and which author's rule made them strong is more useful than a number. It is also the only version you can argue with.
What To Actually Go Do
Pull up a comparison you already know, ideally one whose ending you know.
Then run one search and one search only. Find every Saturn contact between the two charts, in both directions, out to about 4 degrees. Write down which planet Saturn touched and how tight it was.
Then do the same for Sun and Moon contacts, any aspect, because any aspect beats none.
Two pieces of information come out of that. Whether the comparison had the binding contacts the literature says duration needs, and whether it had the vital Sun and Moon links at all. Neither one is a verdict, and you should resist writing one. But if you have been carrying around a story where Saturn was the villain, the exercise tends to rearrange it.
Frequently Asked Questions
What Is The Single Best Synastry Aspect?
The sources do not name one. If forced, the Sun and Moon conjunction between charts, which March and McEvers call the classic bond in a union. Their more important statement is that any Sun and Moon aspect beats none.
Are Saturn Contacts Bad?
They are heavy, and they are what the literature says a lasting union requires. Difficult and necessary are not opposites here. A comparison with no Saturn contact tends to describe something intense that never develops obligations.
Do Squares Mean The Relationship Will Fail?
No. A square between charts describes friction with a specific shape, usually a contest over authority in whatever those two planets govern. It draws people together. Whether it is workable depends on which planets, how tight, and what else is in the comparison.
What About Pluto, Uranus And Neptune Contacts?
Weight them down unless one of three conditions applies: a close conjunction to a planet, a close conjunction to an angle, or a significant age gap between the two people. Between people of the same generation, outer to outer contacts are usually a fact about the generation rather than about the pair.
How Tight Does An Aspect Need To Be?
Under 4 degrees to be read early, under 2 degrees to count as shared experience in Arroyo's sense. Wider aspects still count, they are simply weaker.
Recommended Reading
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- Stephen Arroyo, Relationships and Life Cycles, "Systematic Outline of Synastry," parts I and II, for the reading order, the orb thresholds, the personal planet emphasis, the repetition rule, and the concentration rule.
- Marion March and Joan McEvers, The Only Way to Learn About Relationships, Vol. 5, on Sun and Moon links, aspect type, and Saturn as the binding factor.
- Kevin Burk, Astrological Relationship Handbook, on weighting the inner planets and beginning from elemental balance and dignity.
- Steven and Jodie Forrest, Skymates, on reading the charts separately, orb as a strength modifier rather than a gate, and entering each contact twice.
Continue Learning
Next: how to read a synastry chart and synastry house overlays.