How is the trine angle of 120 degrees derived?

120 degrees divides the circle into 3 equal parts. Aspects are ratios of the circle rather than arbitrary distances, which is why the major set is small: the major aspects come from the simplest divisions, and each further subdivision produces a narrower, more contested aspect.

What orb should a trine use?

This site uses 7 degrees by default for the trine. Orb is a convention, not a measured quantity: there is no agreed value, practitioners commonly tighten orbs for minor aspects and for slow-moving bodies, and some assign orb to the planets involved rather than to the aspect. Widen the orb and more aspects appear; narrow it and the same chart looks sparse. Any aspect list is therefore only comparable to another when both state the orb used.

Is the trine a good or bad aspect?

Classical sources class the trine as harmonious, meaning the two bodies cooperate easily. Ease is not the same as benefit - an easy aspect between difficult bodies simply makes that difficulty flow without resistance.

Trine

120°·harmonious·major·default orb ±7°

Classical source

Ptolemy classifies the trine as one of the harmonious aspects, formed by signs of the same triplicity (element). Considered fortunate.

Modern Western reading

Modern reading: effortless flow between two principles. Often described as flowing, supportive, sometimes complacent.

Trine between two planets

Cited reference for this aspect between each pair of planets. Inner-planet pairs only list aspects their orbits can actually form.

Other aspects

Questions

What is a trine in astrology?: A major aspect of 120 degrees. Ptolemy classifies the trine as one of the harmonious aspects, formed by signs of the same triplicity (element). Considered fortunate. Modern reading: effortless flow between two principles. Often described as flowing, supportive, sometimes complacent.
How is the trine angle of 120 degrees derived?: 120 degrees divides the circle into 3 equal parts. Aspects are ratios of the circle rather than arbitrary distances, which is why the major set is small: the major aspects come from the simplest divisions, and each further subdivision produces a narrower, more contested aspect.
What orb should a trine use?: This site uses 7 degrees by default for the trine. Orb is a convention, not a measured quantity: there is no agreed value, practitioners commonly tighten orbs for minor aspects and for slow-moving bodies, and some assign orb to the planets involved rather than to the aspect. Widen the orb and more aspects appear; narrow it and the same chart looks sparse. Any aspect list is therefore only comparable to another when both state the orb used.
Is the trine a good or bad aspect?: Classical sources class the trine as harmonious, meaning the two bodies cooperate easily. Ease is not the same as benefit - an easy aspect between difficult bodies simply makes that difficulty flow without resistance.

Reference, not advice

This is cultural and astronomical reference, not personal prediction or advice.

Aspect classifications follow classical Western convention. Different traditions assign slightly different orb budgets - the values shown are conservative defaults used throughout this site.

Sources

Ptolemy, Tetrabiblos

Last reviewed 2026-05-28.