Aspects in astrology: what they are and how to read them

An aspect is an angle between two planets or points of a chart, measured along the ecliptic, that astrology treats as meaningful. Signs and houses describe which functions a person has and where they operate; aspects show how those functions relate to each other: whether they support each other, argue, or fuse into one. Without aspects a chart falls apart into a list of separate placements, which is why they are usually taught right after planets, signs and houses.

Where the idea comes from

The word comes from the Latin aspectus, a look or a gaze. The old metaphor is simple: at certain distances planets "see" each other, at others they do not.

The system astrologers still use was set out by Ptolemy in the Tetrabiblos in the 2nd century. He described four angles produced by dividing the circle into equal parts: into two (the opposition, 180°), three (the trine, 120°), four (the square, 90°) and six (the sextile, 60°). Later tradition added the conjunction as a fifth. Together these five are called the Ptolemaic or major aspects.

Early authors judged aspects mainly by sign: any planet in Aries was in trine to any planet in Leo, whatever the degrees. Later astrologers moved to exact angles with an allowed margin, and that is how modern software calculates aspects.

Major and minor aspects

Beyond the five Ptolemaic aspects there are minor ones. The most common are:

• the semi-sextile, 30°;
• the semi-square, 45°;
• the quintile, 72°;
• the sesquiquadrate (a square and a half), 135°;
• the biquintile, 144°;
• the quincunx or inconjunct, 150°.

Some of these, the quintile among them, were introduced by Johannes Kepler in the early 17th century. Minor aspects are used with a very small margin and read as extra nuance: the five major aspects cover most work, and a minor aspect rarely changes the overall picture of a chart. The quincunx is the usual exception, because it is part of the yod configuration.

Soft and hard: a useful simplification

Aspects are often split into two groups. The sextile and trine are called harmonious or soft: the planets support each other and energy flows easily. The square and opposition are called tense or hard: the planets pull in different directions. The conjunction stands apart, since its character depends on which planets meet in it.

The split is handy for beginners, but it is crude. A soft aspect does not guarantee a good outcome: a trine gives a talent that a person may never use, because nothing pushes them to. A hard aspect does not mean trouble: squares and oppositions often describe the area of life where a person works hardest and achieves the most. Planets also keep their own nature. Mars trine Saturn and Venus trine Jupiter are both soft aspects, yet they read nothing alike.

Orbs: how exact the angle must be

Exact 90° or 120° angles between planets are rare. Astrologers therefore allow a margin around the exact angle, called the orb. A square at 87° or 93° still counts as a square if the deviation fits within the allowed orb. The smaller the actual orb, the stronger the aspect.

There is no single standard for orbs: schools differ, the Sun and Moon usually get more room and minor aspects less. The approaches and typical values are covered on the page about aspect orbs.

Applying and separating aspects

In every pair one planet moves faster than the other. If the faster planet has not yet reached the exact angle and the orb is shrinking, the aspect is applying. If the exact angle has been passed and the orb is growing, the aspect is separating. Tradition treats an applying aspect as stronger: whatever it describes still lies ahead. A separating aspect reads as something already familiar and absorbed.

Retrograde planets complicate this, because they move backwards. It is safer to take the direction from the calculation than to judge it by eye.

Out-of-sign aspects

Sometimes the angle between two planets matches an aspect while the signs do not. A planet at 28° Aries and another at 2° Virgo are 124° apart, a trine by orb. But Aries is fire and Virgo is earth, and by sign the two form a quincunx, not a trine. In the same way 29° Cancer and 2° Leo make a conjunction by degree, even though the planets sit in different signs.

These are called dissociate or out-of-sign aspects. Most astrologers count them but read them more softly: the link between the planets is there, the usual relationship of elements or modalities is not.

How to read an aspect

An aspect is read in three layers.

Planets. Which two functions meet. The Sun stands for will and self-expression, the Moon for needs and emotional responses, Mercury for thinking and speech, Venus for values and relationships, Mars for action, Saturn for limits and responsibility. The first question is always what exactly the aspect connects.

Signs. How each planet acts. The sign sets the style: Mars in Leo acts openly and for an audience, Mars in Virgo carefully and by calculation. The elements and modalities of the signs explain why an aspect works the way it does. In a square both signs share a modality but differ in element; in a trine they share an element.

Houses. Where it plays out. An opposition between planets in the 4th and 10th houses stretches the axis of home and family against career and public role. Without an accurate birth time this layer is not available.

On top of that, weigh the orb, the direction of motion, and whether the aspect is part of a larger figure. Two squares and an opposition can form a T-square, three trines a grand trine. Such configurations are read as a whole.

Example: the aspects in Donald Trump's chart

Here are the major aspects in Donald Trump's chart (14 June 1946, 10:54, New York, Rodden rating AA), sorted by orb:

Aspect	Signs	Orb
Jupiter trine Uranus	Libra, Gemini	0°26′
Sun opposition Moon	Gemini, Sagittarius	1°43′
Venus conjunction Saturn	Cancer, Cancer	1°55′
Mercury square Neptune	Cancer, Libra	3°01′
Moon opposition Uranus	Sagittarius, Gemini	3°18′
Moon sextile Jupiter	Sagittarius, Libra	3°45′
Sun sextile Mars	Gemini, Leo	3°50′
Neptune sextile Pluto	Libra, Leo	4°12′

The first thing to notice is how few there are. Ten planets give 45 possible pairs, and only eight of them form a major aspect within the orbs AstroWay uses. Most real charts look like this.

Second, the aspects differ in weight. The Sun-Moon opposition at 1°43′ links the two lights and is one of the central axes of the chart: Trump was born at a full Moon, on the day of a lunar eclipse. The Sun is in the 10th house and the Moon in the 4th, so the opposition falls exactly on the axis of family against public role. Jupiter trine Uranus is the tightest aspect between planets. Neptune sextile Pluto, with the widest orb, links the two slowest planets and is shared by a whole generation, so it says the least about the individual.

Third, every aspect here is within its signs; none is out of sign. There is only one square, Mercury to Neptune, and it is covered in detail in the article on the square.

How to find the aspects in your own chart

You do not have to measure angles by hand. The AstroWay birth chart calculator builds an aspect table: each row gives the two planets, the type of aspect, the actual orb and whether the aspect is applying or separating. The table is sorted from the tightest aspect to the widest, so it makes sense to start reading from the top.

A practical order of work: first find the aspects of the Sun, the Moon and the ruler of the Ascendant, since they say the most about the person. Then check whether the chart contains any configurations. Only after that turn to aspects between the slow planets.

In this section

• Conjunction, 0°: two planets act together.
• Sextile, 60°: an opportunity that needs a step.
• Square, 90°: friction that demands action.
• Trine, 120°: an easy flow between signs of one element.
• Opposition, 180°: two poles of one axis.
• Minor aspects: semi-sextile, semi-square, quintile, sesquiquadrate, biquintile and quincunx.
• Aspect orbs: how far from the exact angle still counts.
• Configurations: T-square, grand cross, grand trine, kite, mystic rectangle, grand sextile, yod, stellium.

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