How is the semisextile angle of 30 degrees derived?

30 degrees divides the circle into 12 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 semisextile use?

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

Neither by itself. The semisextile is classed as neutral: its effect follows the bodies involved rather than the angle, so the same aspect reads very differently between, say, two benefics and two malefics.

Semisextile

30°·neutral·minor·default orb ±2°

Classical source

Adjacent-sign aspect (30°). Classical sources treat it as minor and somewhat dissonant due to lack of shared element or modality.

Modern Western reading

Modern reading: subtle adjustment. Two principles in adjacent signs requiring small course corrections to integrate.

Semisextile 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 semisextile in astrology?: A minor aspect of 30 degrees. Adjacent-sign aspect (30°). Classical sources treat it as minor and somewhat dissonant due to lack of shared element or modality. Modern reading: subtle adjustment. Two principles in adjacent signs requiring small course corrections to integrate.
How is the semisextile angle of 30 degrees derived?: 30 degrees divides the circle into 12 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 semisextile use?: This site uses 2 degrees by default for the semisextile. 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 semisextile a good or bad aspect?: Neither by itself. The semisextile is classed as neutral: its effect follows the bodies involved rather than the angle, so the same aspect reads very differently between, say, two benefics and two malefics.

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.