Opposition

The opposition is an aspect of one hundred and eighty degrees, formed when two planets stand directly across the circle from one another, half its span apart. It is one of the five major, or Ptolemaic, aspects, and with the square one of the two hard aspects. One hundred and eighty degrees sets planets in signs of the same mode and complementary element face to face, and the tradition reads the opposition as confrontation, polarity, and the tension of two forces pulling in contrary directions, often projected onto other people and relationships, where the opposed energies are met in another. Like the full moon, which is an opposition of Moon and Sun, it carries a quality of culmination and awareness. It is given a wide orb. These are the interpretive conventions of the astrological tradition for this angular relation between planets.

Book I.13 of Ptolemy's Tetrabiblos, compiled in Alexandria in the second century CE, names the opposition alongside the trine, quartile and sextile as one of only four figures the earliest systematic source recognises, the conjunction being treated separately as no aspect at all. Hellenistic astrologers read it through the same whole-sign lens Vettius Valens applies throughout his Anthology of around 175 CE, as two planets set at the full stretch of the circle from one another, each looking the other directly in the face with no intervening sign to soften the contact. The now-common psychological reading, that the querent identifies with one end of the axis and meets the other in the people around them, is a reinterpretation dating from the twentieth century; the older texts describe the same geometry as straightforward enmity and confrontation and offer no theory of projection at all.

The opposition is the simplest aspect to find and the hardest to soften. A hundred and eighty degrees halves the circle, and the signs it joins are always of the same modality and of complementary elements: fire opposes air, earth opposes water. Every sign has exactly one opposite, and the pairs are fixed, so the axis a planet stands on can be named before anything else about the chart is known.

Counting it by sign and counting it by degree almost always agree, which is unusual. Because the opposition spans a full six signs, a planet early in one sign and a planet late in its opposite are still within a generous orb of the exact angle in most systems, so the sign-based and degree-based readings rarely part company the way they do for the square or the sextile. The practical disputes about the opposition are therefore not about whether it is present but about what it does.

Traditional sources place it with the square among the configurations of enmity and pair it with obstruction, open conflict and things that come to a person from outside. Modern psychological practice reads the same angle as a demand for integration between two functions that are each incomplete, and treats projection, the attribution of one end of the axis to another person, as its characteristic mechanism. That reading belongs to the twentieth century and to the psychological turn in astrology generally; it is not what an ancient source means by the term. Both are in circulation, and they lead to different advice.

The opposition is fundamental to the Hellenistic aspect doctrine given systematic form by Ptolemy, and like the sextile, square and trine, rather than the conjunction, it belongs among the four configurations he counted as true aspects, since bodies six signs apart look directly across the circle at one another. Its glyph is two small circles joined by a straight line, the pairing of circles standing for the two bodies and the connecting stroke for the diameter between them, a shape distinct enough from the conjunction's single circle and hook that confusion between the two marks was unlikely even in cramped manuscript margins.

The sign is attested with the other aspect glyphs in the medieval Byzantine codices that preserve Greek horoscopes, and it was carried into the standardised printed tables of the Renaissance largely unchanged. Among the aspect marks it is one of the minority to have been given a dedicated Unicode codepoint of its own, OPPOSITION at U+260D in the Miscellaneous Symbols block, encoded since the first release of the Unicode Standard in 1993 rather than left to be improvised from letters or general-purpose geometric characters, as several of the minor aspects still are.