Angle and Origin

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.