Angle and Origin

The conjunction is fundamental to the aspect doctrine set out in the Hellenistic tradition and given its lasting theoretical shape by Ptolemy in the second century. Aspect thinking of this kind was not his invention; Dorotheus of Sidon, whose Carmen Astrologicum is usually dated to the first century, already worked with the same angular relationships, so the doctrine Ptolemy systematised had been circulating among Greek astrologers for some generations before he wrote it down.

In chart work the conjunction is written with a small circle carrying a short radial arm or hook, a mark attested alongside the other planetary and aspect signs in the medieval Byzantine codices that preserve so many ancient Greek horoscopes, and later regularised into its familiar printed form as astronomical and astrological tables began to be typeset in the Renaissance. The symbol was given a dedicated place in digital type comparatively early: it appears in the Unicode Standard as CONJUNCTION, U+260C, in the Miscellaneous Symbols block, present since the standard's first release in 1993, one of only a handful of aspect glyphs to receive their own codepoint rather than being built from letters or borrowed geometric shapes.