♇ and are the astronomical and astrological symbols representing Pluto. This celestial body was named after Pluto (Πλούτων), the Greek and Roman god of the underworld, whose earlier Greek name was Hades (ᾍδης).
Pluto is not a classical planet and was unknown to alchemists. It was discovered in 1930 by Clyde Tombaugh after almost a year of systematic search for trans-Neptunian “Planet X” predicted by Percival Lowell and William Pickering. Pluto was enjoying the status of planet until 2006 when it was reclassified (or “plutoed”) as a dwarf planet by International Astronomical Union (IAU).
The astronomical symbol for Pluto, ♇, which looks like a flipped and flopped Cyrillic letter Б, is a monogram of the letters “P” and “L” which could be interpreted as the initials of Percival Lowell or “Pickering—Lowell”.
The astrological symbol for Pluto, , is more in line with other planetary symbols. According to Wikipedia, the circle represents Pluto’s Cap of Invisibility and the arc under the circle represents bident (not to be confused with bidet). Also, it could be thought of as a symbol of Mercury, ☿, with circle and arc swapped. I like this latter symbol more because it looks like a flower.
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