Discovery and Glyph

Pluto was discovered by Clyde Tombaugh in 1930. Its glyph is a monogram of the letters P and L, which also stand for the initials of the astronomer Percival Lowell, whose observatory sought it. The double meaning was almost certainly intentional: Lowell had predicted a ninth planet from irregularities he believed he saw in the orbits of Uranus and Neptune and spent years searching for it before his death, and the monogram let the new planet's sign honour both its mythological namesake and the astronomer whose observatory, and whose initials, made the discovery possible. Since the 2006 reclassification, many astrologers and even NASA itself have shifted toward a different glyph, a bident topped by a small circle or orb, distancing Pluto's symbol from the original PL monogram without abandoning the planet's place in practice. Unicode encoded the original monogram with the rest of the astrological set in 1991 and has since fielded several later proposals for alternative Pluto glyphs reflecting this divided modern usage, though none of the alternatives has yet been formally added to the standard alongside the original sign. Pluto's short, crowded symbolic history, a schoolgirl's suggested name, an astronomer's memorialised initials, and now a second, unofficial glyph competing with the first, compresses into under a century a dispute over meaning and representation that took the seven classical planets the better part of two millennia to work through.