Meaning
An opposition puts two bodies on opposite sides of the zodiac, six signs apart. Opposite signs share their modality and their kind in Ptolemy's scheme, both masculine or both feminine, and their elements are partners, fire facing air and earth facing water: Aries faces Libra, Taurus faces Scorpio. Ptolemy still classes the opposition with the square as discordant, the two bodies looking straight at each other across the chart.
The tradition reads it as tension, confrontation and the need to balance two ends of one axis, an aspect often lived out through other people, who seem to carry the other end. Modern astrology calls it a hard aspect; our readings call it tension and balance, never misfortune.
A full moon is the Sun and the Moon in opposition. Our chart names the Moon's phase in Rudhyar's scheme; for a birth with the Moon within 10° either side of the Sun's opposite point, the luminaries are also in this aspect. In the sample chart on our system page the closest aspect of all is an opposition: the Moon in Cancer and Saturn in Capricorn, about a hundredth of a degree from exact.
Our orbs
We allow 10° when the Sun or Moon is in the pair and 8° otherwise, and half that to Chiron, the North Node and the angles. Within a quarter of a degree it is marked exact. Our chart draws oppositions, like squares, as solid lines.
The North and South Nodes are always exactly opposite, by definition. Until October 2026 our chart listed "North Node opposition South Node, exact" in every chart; it told no one anything, so we now give the South Node no aspects at all. The Ascendant and Descendant, and the Midheaven and IC, are likewise opposite in every chart and are not listed.
Other schools
astro.com's default and ours agree on 10° for the luminaries; its classical style scales the orb by planet, as Lilly did, and CHANI counts by sign. In Jyotisha every graha casts its aspect on the seventh sign from itself, the opposition counted by sign.
Correspondences
Each item with how it stands: “sourced” is in the work cited, “our construction” is EsoTerrier’s own, and “disputed” means the sources disagree.
- Angle (Ptolemy)
- 180° sourced
- Class (Ptolemy, in Ashmand)
- disharmonious sourced
- Modern class
- hard or challenging sourced
- A musical interval
- A modern table; Kepler built aspects on harmonic ratios in 1619, Ptolemy on halves and thirds of the circle disputed
- Invented by Ptolemy
- No: in use before him; "Ptolemaic" records his later authority disputed
- One standard orb
- No: orbs differ by school disputed
- Our orbs
- 10° with the Sun or Moon, 8° otherwise, half to the points our construction
How the schools read it
- Ptolemy (2nd century CE)
- Disharmonious: the two ends of one axis, facing each other.
- astro.com default
- 10° for every pair, points at half.
- astro.com classical style
- Orbs by planet: luminaries 9°, Mercury, Venus and Mars 7°, the outer planets 5°.
- CHANI
- Aspects counted by whole sign, not by degree.
- Kepler (1619)
- Built the aspects on harmonic ratios and added the quintile, biquintile and sesquiquadrate.
- Jyotisha
- No aspects by degree: each graha aspects the seventh sign from it, and Mars, Jupiter and Saturn further signs.
- EsoTerrier
- 10° with a luminary, 8° otherwise; applying or separating; called tense.
Claims about it
-
Ptolemy invented the five major aspects, which is why they are called Ptolemaic.
disputedWhat the record shows: He lists the configurations, but the aspects were in use before him and Valens uses them without crediting him; "Ptolemaic" records his later authority, not an invention.
-
One set of orbs, such as 10° for every aspect, is the standard.
disputedWhat the record shows: Orbs differ by school: Lilly gave each planet its own; astro.com's default is a flat 10°, 6° for the sextile; others scale by planet; CHANI counts by sign. Ours are printed with every chart.
