Pluto

Also called the PL monogram, ♇

Found 18 February 1930; dwarf planet from 24 August 2006

Pluto meaning

Pluto was found by Clyde Tombaugh on 18 February 1930 at Lowell Observatory. The sign ♇ is a monogram of P and L for Percival Lowell. On 24 August 2006 the International Astronomical Union classed it as a dwarf planet. The character did not get retired.

♇U+2647

A monogram for Percival Lowell that outlived the category the planet was put in.

The name. Pluto is the Roman name of the god of the underworld. Venetia Burney, an eleven-year-old in Oxford, suggested it. The initials P and L also honored Percival Lowell. The glyph is that coincidence made into a picture.

Download drawing

Where it comes from

Percival Lowell had searched for a planet beyond Neptune and died in 1916 without a confirmed find. Clyde Tombaugh, hired at Lowell Observatory, found the moving point on plates compared in 1930. The announcement was 13 March, the anniversary of Herschel’s Uranus and of Lowell’s birth. The name came from outside the observatory. Venetia Burney proposed Pluto. The P and L served the god and the patron at once, which is why the glyph is a monogram and not a divine attribute in the way Neptune’s is a trident. Unicode encodes it as PLUTO, U+2647, ♇. For most of the twentieth century schoolbooks counted nine planets. On 24 August 2006 the IAU, meeting in Prague, defined a planet in a way Pluto does not meet. It is a dwarf planet. The vote changed a category. It did not delete a character, and it did not unsay the 1930 plates. Astrology had already assigned the body a set of meanings, underworld and transformation among them, in the decades after the find. Those meanings do not depend on the IAU’s noun. They also do not become older than 1930. A chart that treats ♇ as an ancient underworld rune is skipping the monogram. It is Lowell’s initials before it is a theology.

Astrology

A late god for a late light

The underworld reading follows the name. Pluto the god is old. Pluto the planet is 1930. Modern astrology needed a body for what Saturn and Neptune were said not to cover, and it used the new one. That is a school making room. It is not a recovery of a sign that medieval astrologers had misplaced. There was no sign to misplace. The monogram is the whole of the authentic glyph. Anything more elaborate is decoration.

Modern

The category moved

Eight planets is the count after 2006. Nine was the count in the books Tombaugh’s discovery rewrote. Seven was the count the metals were built on. All three sentences can be true if you date them. The glyph is indifferent to the vote. Fonts still have ♇. A lexicon that deleted the page because of a definition would be confusing a noun with a mark. The page stays. It says dwarf planet when it is talking about 2006, and it says planet when it is talking about the announcement in 1930.

In popular culture

tv · 1992

Sailor Moon (Sailor Pluto)

Setsuna Meiou's dark-red ♇ monogram marks the Guardian of Spacetime; read as time, isolation and death.

The anime borrows the astronomical glyph as a character badge that appears on the forehead at awakening.

Source

film · 1931

Pluto (Disney)

Mickey's dog was named Pluto in 1931, a year after Lowell Observatory announced the planet's name.

The dog took the name, not the glyph.

Source

other · 2015

NASA/JPL Dawn dwarf-planet poster

Used the bident form ⯓ among symbols assigned to the five dwarf planets.

An astronomy use of the astrological variant.

Source

Worth knowing

♇ is a PL monogram: Pluto's first letters and Percival Lowell's initials. U+2647. Source
The orb-over-bident astrological symbol dates to the early 1930s; the orb may be Pluto's cap of invisibility. Source
The IAU style manual discourages planet symbols in journals, preferring letter abbreviations (Me, V, E, Ma, J, S, U, N). Source

Questions

What does the Pluto mean?

How do I type the Pluto?

The character is ♇ (U+2647).

Why does Sailor Moon use Pluto?

Setsuna Meiou's dark-red ♇ monogram marks the Guardian of Spacetime; read as time, isolation and death. The anime borrows the astronomical glyph as a character badge that appears on the forehead at awakening.

Why does Pluto use Pluto?

Mickey's dog was named Pluto in 1931, a year after Lowell Observatory announced the planet's name. The dog took the name, not the glyph.

Near this

Sources

Named when the entry depends on a text, a date, or a standard. Catalog numbers are not invented.

Your margin

Private. It stays in this browser and never joins the canon.

symbol.wiki, edited as Sigilla. Last reviewed 20 October 2026. A reading of public tradition, not a ruling.