How is the opposition angle of 180 degrees derived?

180 degrees divides the circle into 2 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 opposition use?

This site uses 8 degrees by default for the opposition. 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 opposition a good or bad aspect?

Classical sources class the opposition as challenging. 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.

Opposition

180°·challenging·major·default orb ±8°

Classical source

Ptolemy lists opposition as one of the five Ptolemaic aspects, formed by the diameter (180°). Classically described as obstructive or confrontational.

Modern Western reading

Modern reading: polarity and projection. The two bodies pull in opposite directions, asking for balance between contrasting principles.

Opposition 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 opposition in astrology?: A major aspect of 180 degrees. Ptolemy lists opposition as one of the five Ptolemaic aspects, formed by the diameter (180°). Classically described as obstructive or confrontational. Modern reading: polarity and projection. The two bodies pull in opposite directions, asking for balance between contrasting principles.
How is the opposition angle of 180 degrees derived?: 180 degrees divides the circle into 2 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 opposition use?: This site uses 8 degrees by default for the opposition. 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 opposition a good or bad aspect?: Classical sources class the opposition as challenging. 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.