Trine in astrology

The four trines, one per element

A trine is the aspect between any two of the three signs that share an element. Because the zodiac has four elements and twelve signs, there are exactly four trine families, and each sign belongs to one.

Why 120 degrees means the same element

The elements repeat every fourth sign: fire, earth, air, water, then fire again. Four signs is 120 degrees, so any two planets that meet the angle are in signs of one element. The signs are always in different modalities, which means a trine pairs a cardinal sign with a fixed one and a mutable one. This is why the contact feels familiar: the two planets speak the same temperamental language, but each expresses it in its own way.

At the commonly used orb of up to 8 degrees, a trine covers 112 to 128 degrees. The glyph △︎ is a triangle, which is also where the name comes from, as the three trine signs of an element form an equilateral triangle when drawn on the circle.

A worked example by hand

You can test a trine without software. Count each planet's position in degrees from the start of Aries.

1. 1. Convert to a position on the circle

   Venus at 12 degrees of Aries is at 12. Mars at 14 degrees of Leo is at 134, because Leo begins at 120.

2. 2. Subtract

   134 minus 12 is 122 degrees. If the answer is above 180, subtract it from 360 first.

3. 3. Compare with 120

   122 is 2 degrees from exact, inside any commonly used orb, so Venus is trine Mars. Both signs, Aries and Leo, are fire.

The catch with an easy aspect

The traditional reading is that a trine is a gift, but a gift can sit unopened. Because nothing resists, the ability may never be developed. Astrologers often point out that the people who use a trine well are the ones who also have a square or opposition pushing the same planets into action. Alone, a trine is described as comfortable and a little passive.

Patterns built from trines

• A grand trine is three planets each 120 degrees from the next, all in one element. It is the closed loop of the aspect, read as self-sufficient energy that can turn inward.
• A kite adds a fourth planet in opposition to one corner of a grand trine, which gives the loop an outlet.
• A mystic rectangle is two oppositions joined by two trines and two sextiles, and it is rarer.
• Out-of-sign trines, such as 28 degrees of Aries with 2 degrees of Virgo (124 degrees apart), are inside the orb but sit in different elements, fire and earth, so the tradition weights them lower.

Trines between fast planets and slow ones

How long a trine lasts depends on the speed of the planets. The Moon moves about 13 degrees a day, so a trine from the Moon to another planet is exact for a matter of hours. A trine between two outer planets can stay within orb for years and is shared by everyone born in that stretch, which is why astrologers call those generational aspects. Personal trines, those that involve the Sun, Moon, Mercury, Venus or Mars with a slower planet, are the ones that tell one chart from another.

The same difference applies to transits. A planet passing through a trine to your natal Sun for a day or two is a short mark on the calendar, while a slow planet making the same trine can run for several months.