Ninety-six years ago today, a small, frozen world at the edge of our solar system was given a name that would capture the imagination of generations. The official naming happened on March 24, 1930, though the public announcement came a little later, on May 1 of that year. The story of how Pluto got its name — and everything that followed — is one of the more charming and unexpectedly human tales in the history of astronomy.
A Discovery, and a Deluge of Suggestions
Pluto was discovered earlier that year by a young astronomer named Clyde W. Tombaugh, working at Lowell Observatory in Flagstaff, Arizona. The announcement of his discovery triggered an outpouring of public enthusiasm: over a thousand naming suggestions flooded in from around the world. Three names rose to the top of the list — Minerva, Cronus, and Pluto. Minerva was the staff’s sentimental favorite, but it had already been claimed by an asteroid. Cronus was quietly set aside, in part because it was championed by Thomas Jefferson Jackson See, an astronomer so thoroughly disliked by his peers that his endorsement was apparently more of a liability than an asset.
That left Pluto.
An Eleven-Year-Old’s Idea
Among the roughly 150 letters and telegrams nominating the name Pluto, the very first had come from the most unlikely of sources: Venetia Burney, an eleven-year-old schoolgirl in Oxford, England, who had a keen interest in classical mythology. She mentioned the idea over breakfast to her grandfather, who passed it along to an astronomy professor, who cabled it to the Lowell Observatory. The name stuck.
It was, on reflection, a perfect fit. Pluto was the god of the underworld — one of six surviving children of Saturn — and every one of his siblings had already lent their name to a planet. More poetically, both the god and the distant world he now represented inhabited gloomy, lightless realms, and the god was famously able to make himself invisible, just as the planet had managed to remain hidden from human eyes for so long.
A Name That Rippled Through Culture
The name Pluto quickly escaped astronomy and seeped into the wider world. Later in 1930, Walt Disney reportedly drew inspiration from it when he gave Mickey Mouse a new canine companion — also named Pluto. Then in 1941, the nuclear chemist Glenn T. Seaborg named a newly synthesized element plutonium after the planet, following the longstanding tradition of naming elements after celestial discoveries. Not bad for a frozen rock three and a half billion miles away.
A World Worth Knowing
Pluto is, by any measure, a remarkable place. It’s only about 1,400 miles wide — roughly half the width of the United States — and sits some 3.6 billion miles from the Sun. Its year is so long that it won’t complete a single orbit since its discovery until the year 2178. Its thin atmosphere is a mix of nitrogen, methane, and carbon monoxide, and its surface temperature averages around -387°F (-232°C), making it one of the most hostile environments imaginable.
For most of its known existence, Pluto was little more than a faint smudge of light in a telescope. That changed dramatically in July 2015, when NASA’s New Horizons spacecraft — launched in 2006 and nine years in transit — made the first and so far only close flyby of the planet. The images it returned were astonishing. Pluto turned out to be a geologically active world with a surprisingly young surface, featuring a vast heart-shaped glacier of nitrogen ice, towering water-ice mountains, possible cryovolcanoes, a layered hazy atmosphere, and tantalizing hints of a subsurface ocean. It was not the dead, featureless ball many had expected.
The Demotion Heard Around the World
By then, however, Pluto had already suffered a significant blow to its status. Starting in 1992, astronomers began discovering other objects orbiting in the same distant region of the solar system — a vast ring of icy bodies now known as the Kuiper Belt. It became clear that Pluto wasn’t a lone oddity but a member of a much larger population. In 2006, the International Astronomical Union officially reclassified it as a “dwarf planet,” ruling that it had not cleared its orbital neighborhood of other debris — one of the three criteria required for full planetary status.
The public reaction was, to put it mildly, not indifferent. New Mexico — home to Clyde Tombaugh for much of his life — passed a resolution declaring that Pluto would always be considered a planet in New Mexican skies, and designated March 13, 2007, as Pluto Planet Day. Illinois, where Tombaugh was born, followed with its own resolution in 2009. And in April 2024, Arizona — the state where Pluto was first discovered — went one step further, passing a law officially designating Pluto as the state planet.
Science may have changed Pluto’s classification, but it hasn’t dimmed the world’s affection for it. Ninety-six years after an Oxford schoolgirl suggested the name over breakfast, Pluto remains one of the most talked-about, debated, and beloved objects in the solar system. Not bad for a dwarf planet.