Trine aspect: the 120° angle and the harmony of elements

In the Tetrabiblos (book I, chapter 13), Ptolemy describes the trine as the interval of four signs, 120°, one and a third right angles. He justifies it by the ratios of music: the ratio of the trine to the square is sesquitertian, that is, 4 to 3, as 120° is to 90°.

He then places the trine and the sextile among the harmonious aspects, because they join signs of the same kind, all masculine or all feminine. The trine goes further than the sextile: its signs also share the element. Aries, Leo and Sagittarius thus form the Fire trine, and each element has its own.

William Lilly, in Christian Astrology (1647, book I, chapter XIX), calls the trine a triangular or trigonal aspect. With the sextile, he makes it an argument of love, unity and friendship, and specifies that the trine is the more forcible of the two: if two significators are in sextile or trine, peace may easily be concluded.

Lilly also distinguishes two degrees of precision. A partile trine is exact to the degree: Mercury at 9° Aries and Jupiter at 9° Leo. A platic trine allows a gap, as long as it stays within half the orbs of the two planets. His example: Venus at 10° Taurus and Saturn at 18° Virgo are 8° from the exact trine, and the aspect holds, since half their orbs come to 4° and 5°, or 9° together.

Finally, he points out a learned word: trigonocrator, the planet that rules a triplicity, that is, a group of three signs of the same element. The trine and the triplicity come from the same division of the zodiac, and AstralPro calculates the triplicity rulers among the dignities of your chart.

The trine lets energy flow between two functions that support each other without resistance. The legend of the aspect table in your report sums it up in one word: harmony. To read it, identify the two functions at stake and see how each makes things easier for the other. With the Sun trine the Moon, what you want and what you feel agree naturally, between inner life and outward expression.

This fluidity is no guarantee. An available resource can go unused, precisely because it demands nothing. The trine describes a starting ease on which you can build your development, and whose ground is specified by the house and sign of each body.

The shared element sets the tone of the agreement. A Fire trine links two functions through drive, an Earth trine through the concrete, an Air trine through the exchange of ideas, a Water trine through sensitivity. And as with any aspect, the Direction column of your grid says whether it is still forming or has already formed, when that direction can be read.

Ptolemy reasons in signs: a trine joins two signs four signs apart. AstralPro measures in degrees: the orb of the trine is 8°, and two bodies 112° to 128° apart are in trine, whatever their signs. The tolerance is the same for all bodies, and the same in the birth chart and in the Book.

The difference is not theoretical. Near sign boundaries, a gap of 113° can join two signs only three signs apart, and therefore of two different elements. This is called an out-of-sign aspect: the trine is counted, but the agreement of elements is missing. To read it, always look at the two signs as well as the orb.

The wheel draws the trine only at 5° or less, the solar return keeps 7° for its internal aspects, and the Book 6° to detect a grand trine, three bodies in trine to one another.

Camille Morel, AstralPro's sample chart (fictional data), has only one trine in her grid of 40 aspects, on line 38: Jupiter trine Saturn, orb 6°57'. Jupiter is at 0°50' Scorpio, Saturn at 23°53' Aquarius. The gap between them is 113°03', 6°57' from the exact trine: the aspect is admitted, just barely.

It is an out-of-sign trine. Scorpio and Aquarius are three signs apart, a square distance, and they share neither element (Water, Air) nor gender. An astrologer counting by signs would see no trine here; AstralPro, which counts in degrees, displays it, and its wide orb says it carries little weight.

In the grid, the name of the aspect appears in green. The Direction column carries a dash: Jupiter and Saturn are both slow bodies, whose mutual direction reverses with their stations and does not describe a tendency of the person. The Reading column also carries a dash, since it only comments on lines up to 3° of orb, the first twenty in this chart.

On the wheel, the line does not appear: 6°57' exceeds the drawing's 5°. The trine is not among the twenty aspects discussed in chapter I, nor in the thirteen sections of Life Domains. It is counted, visible, and left in the background.

This is not a flaw in the chart. A wide, out-of-sign trine between two slow bodies describes a backdrop rather than a living resource, and the selection treats it that way. A few degrees would be enough to change the reading: a Jupiter at 23° Libra, an Air sign, would have formed an almost exact trine with Saturn in the same element, tight enough to rise to the top of the grid with its reading.

Camille's chart carries another trine, outside the grid: Chariklo trine Sun, orb 1°47', among the close contacts of the celestial points, which are kept only as major aspects and at 2° or less.