What is a semisquare in astrology?

A minor aspect of 45 degrees. Half-square (45°), introduced as a minor aspect in Renaissance European astrology. Classified as mildly inharmonious. Modern reading: irritating friction. A weaker echo of the square - small persistent challenges between the two principles.

How is the semisquare angle of 45 degrees derived?

45 degrees divides the circle into 8 equal parts. Aspects are ratios of the circle rather than arbitrary distances, which is why the minor set is small: the minor aspects come from the simplest divisions, and each further subdivision produces a narrower, more contested aspect.

What orb should a semisquare use?

This site uses 2 degrees by default for the semisquare. 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 semisquare a good or bad aspect?

Classical sources class the semisquare as tense. That describes friction between the two bodies, not a verdict: tense aspects are where most sources locate motivation and development, and a chart with none is not a better chart.

Semisquare

45°·tense·minor·default orb ±2°

Classical source

Half-square (45°), introduced as a minor aspect in Renaissance European astrology. Classified as mildly inharmonious.

Modern Western reading

Modern reading: irritating friction. A weaker echo of the square - small persistent challenges between the two principles.

Semisquare 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 semisquare in astrology?: A minor aspect of 45 degrees. Half-square (45°), introduced as a minor aspect in Renaissance European astrology. Classified as mildly inharmonious. Modern reading: irritating friction. A weaker echo of the square - small persistent challenges between the two principles.
How is the semisquare angle of 45 degrees derived?: 45 degrees divides the circle into 8 equal parts. Aspects are ratios of the circle rather than arbitrary distances, which is why the minor set is small: the minor aspects come from the simplest divisions, and each further subdivision produces a narrower, more contested aspect.
What orb should a semisquare use?: This site uses 2 degrees by default for the semisquare. 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 semisquare a good or bad aspect?: Classical sources class the semisquare as tense. That describes friction between the two bodies, not a verdict: tense aspects are where most sources locate motivation and development, and a chart with none is not a better chart.

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.