Conjunction aspect: the 0° angle in a birth chart

A conjunction is an aspect in which two points of a chart stand next to each other on the ecliptic, so the angle between them is close to 0°. It counts as one of the five major aspects and is often called the strongest of them: the two planets do not act on each other across a distance, they act together, as a single unit. A conjunction has no fixed character of its own. Its meaning depends entirely on which planets meet and in which sign.

Geometry: the 0° angle

Every other aspect describes a distance between planets: 60°, 90°, 120°, 180°. The conjunction describes the absence of one. Two planets are conjunct when they occupy the same point of the zodiac or sit close to it, and on the chart wheel they are drawn side by side, often as a single cluster of glyphs.

That makes the conjunction behave differently from the other aspects. In a square or a trine the planets stay separate: one in one sign, the other in another, each with its own element. In a conjunction they usually share a sign and a house, so they take on the same colouring and show up in the same area of life. A conjunction is therefore read as a merger of two functions rather than a conversation between them.

Was the conjunction an aspect at all?

The word "aspect" comes from the Latin for "looking at": planets in aspect see each other across the zodiac. In the Hellenistic tradition that kind of looking was a relationship between different signs. In the Tetrabiblos, Ptolemy describes four configurations of signs: the opposition, the trine, the square and the sextile. Planets in the same sign were not thought of as regarding each other but as being together, sharing one place.

Later tradition added the conjunction to the list, and today the five Ptolemaic aspects are usually given with the conjunction included. In practice the distinction changes little. Every school uses the conjunction, and it is among the first things an astrologer notices in a chart.

The orb of a conjunction

An exact conjunction, with both planets on the same degree and minute, is rare, so astrologers allow a margin called the orb. The conjunction usually gets one of the widest orbs: about 7-8° between personal planets and 8-10° with the Sun or Moon. Slow planets that stay close to each other for months get a narrower orb, otherwise one conjunction would cover half a generation.

The closer the planets, the stronger the conjunction. Within 1-2° they act almost as one; within 7-8° the link is clear, but each planet keeps more of its independence. The norms and the disagreements between schools are covered in aspect orbs.

Like any aspect, a conjunction is either applying or separating. If the faster planet is still catching up with the slower one, the aspect is applying, and tradition considers it stronger. Once the faster planet has passed, the conjunction is separating.

Same-sign and out-of-sign conjunctions

Most conjunct planets share a sign. Some cases sit on the boundary. A planet at 28° Taurus and another at 2° Gemini are only 4° apart, which makes them conjunct by orb. Their signs, however, differ completely: Taurus is earth and fixed, Gemini is air and mutable.

This is called an out-of-sign or dissociate conjunction. Most astrologers count it, while recognising that the merger is incomplete: the planets are close, but each works in its own manner and they often fall in different houses. Chart software lists it as an ordinary conjunction.

When three or more planets gather in one sign, many astrologers call the group a stellium. There the weight shifts from individual pairs to the whole group and the sign it fills.

Conjunctions with the Sun: combustion and cazimi

The oldest special rules concern conjunctions with the Sun. A planet that comes close to the Sun disappears from the night sky in its glare, and traditional astrology described this as stages of weakening.

• Under the beams. The planet is within roughly 15-17° of the Sun. Its influence is muted but still noticeable.
• Combust. The planet is within about 8° of the Sun. Tradition treated it as most weakened: the planet's function is burned up, overpowered by the Sun's will.
• Cazimi. The planet sits almost at the Sun's centre, within roughly 17 minutes of arc. Here the rule reverses, and the planet was considered strengthened, like an adviser received at the throne.

Modern psychological astrologers treat these rules in different ways. Many read a conjunction with the Sun more simply: the planet's function is tightly bound to how the person sees themselves, which makes it hard for them to look at it from the outside. Mercury never moves more than about 28° from the Sun, so a Sun-Mercury conjunction is very common and on its own signals nothing rare.

How to read a conjunction

Because the conjunction has no character of its own, reading it always starts with the planets. Three questions help.

First, are the planets compatible in nature? Venus and Jupiter are both traditionally benefic, and their conjunction pushes in one direction, each amplifying the other. Mars and Saturn pull toward different things, so a conjunction between them describes action that caution keeps restraining, and the person has to find a working rhythm between the two.

Second, which planet is stronger in this sign? If one is in its domicile or exaltation and the other in detriment, the conjunction is not an equal partnership: the first sets the tone and the second adapts to it.

Third, where does it happen? The house holding the conjunction becomes the area of life where both functions converge. The same pair in the 2nd house speaks about money and values; in the 10th, about work and public standing.

Precision matters too. A conjunction within a degree is usually one of the most visible features of a chart, even when the planets involved are otherwise unremarkable.

Conjunctions with the lunar nodes

The lunar nodes are not planets but the two points where the Moon's orbit crosses the ecliptic. The North and South Nodes always stand exactly opposite each other, so a conjunction with one node is automatically an opposition to the other, and the two are read together.

A planet conjunct the North Node is traditionally tied to the direction of growth: its theme expands in the person's life, draws attention and often moves to the foreground. A planet near the South Node reads as something long familiar, a resource the person relies on that no longer takes effort. The nodes move slowly, so the orb used here is small, usually a few degrees.

Example: conjunctions in Donald Trump's chart

In Donald Trump's chart the most prominent conjunction is in Cancer. Venus is at 25°44′, Saturn at 23°48′, an orb of 1°55′. Venus is the faster planet and has already passed Saturn, so the aspect is separating. Both planets share a sign and a house, the 11th, which makes it a clean conjunction with no sign boundary in between. Mercury is in Cancer too, but far back at 8°51′, so it does not join the pair.

How tradition reads the combination: Venus describes affection, taste and what a person values, Saturn describes limits, duration and duty. Together they suggest a serious attitude toward feelings and possessions, respect for what has stood the test of time, and caution in closeness. Cancer adds the themes of family, home and one's own circle.

The same chart has a nodal conjunction as well. The Sun at 22°55′ Gemini stands next to the true North Node at 20°48′ Gemini, an orb of 2°07′. Read traditionally, this amplifies the visibility of solar themes: the way the person presents himself tends to move to the front of the stage.

The conjunction and other aspects

A conjunction rarely stands alone. If one of two conjunct planets aspects a third, the other almost always does too, and the aspect is read to the pair as a whole. The conjunction's counterpart is the opposition: there the two planets do not merge but face each other, and each sees in the other what it lacks itself.

In celebrity charts

The tightest examples among the published charts.

• Kylian Mbappé: Moon conjunction Venus, orb 0°05′
• Narendra Modi: Sun conjunction Mercury, orb 0°06′
• Beyoncé: Moon conjunction Uranus, orb 0°15′

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