Chiron was discovered by Charles Kowal in 1977 and entered astrological practice in the decades that followed. Its glyph is a key-like figure, a circle beneath the letter K, proposed by the American astrologer Al H. Morrison, who is credited with designing the symbol specifically for astrological use rather than adapting an existing astronomical mark. The form reads two ways at once, as a key, evoking Chiron's mythic role as the one who unlocks healing and hidden wisdom, and as a monogram of the letters O and K, standing for Object Kowal, the provisional name under which the discovery was first announced before Chiron received its formal designation.
Unlike the sickle, spear, scepter and hearth of the four asteroids, which trace to nineteenth-century astronomical convention later revived by astrologers, Chiron's glyph was devised for astrology from the outset, and it has remained close to Morrison's original design across the various typefaces used in later astrological software, though later type designers have varied small details, especially the shape of the oval forming the key's bow, without altering the basic circle-and-K composition Morrison established. Morrison introduced the glyph through the astrological press of the period, and because Chiron's discovery fell so soon after Eleanor Bach's asteroid ephemeris had already accustomed astrologers to adopting new symbols for newly catalogued minor bodies, the key glyph found a receptive audience and spread quickly through the emerging literature on Chiron as a distinct chart factor.