Glyph and Origin

Its glyph is a circle topped by a crescent and set above a small cross, often read as the winged cap or caduceus of the god. Mercury is one of the seven classical planets of Mesopotamian and Hellenistic astrology. In the parallel language of alchemy the same sign denoted quicksilver, the liquid metal that shares the planet's Latin name and its associations of swiftness and changeability, and the Romance-language weekday descended from the planet, mercredi in French, is among the clearest surviving traces of the old planetary week in ordinary speech (English Wednesday instead preserves the Germanic god Woden, substituted for Mercury by early translators who judged the two figures comparable).

Alongside the rest of the classical seven, Mercury's sign was encoded in the Miscellaneous Symbols block when Unicode fixed the standard astrological and astronomical glyphs in its 1991 release, giving a symbol assembled piecemeal across more than a thousand years of manuscript copying a single, stable digital identity. Because Mercury shares its rulership between Gemini and Virgo, its glyph is also one of the more frequently printed of the seven in any traditional almanac or ephemeris, appearing wherever the fast-moving planet's shifting position through the signs needs to be tracked in detail.