How Pluto Got Its Name

Back in 2006, Pluto was downgraded to a "dwarf planet" by the International Astronomical Union (via Britannica). The rocky outcropping at the outer regions of our solar system had done nothing wrong, but in a planetary case of "it's not you, it's me," the IAU determined that Pluto didn't meet its standards for what made a planet. For the billions of us here on Earth, that meant ... well, very little, actually, save for some science teachers having to make a few changes to their curricula.

But for seven and a half decades, from its discovery in 1930 to its demotion in 2006, Pluto was the ninth planet from the sun. Three people played a key role in making Pluto what it is today ⁠— or, more accurately, what it was before 2006. One was a scientist who knew it was there but never actually found it, one was a scientist who finally did find it, and the third was a well-read tween girl who named it.

Percival Lowell laid the groundwork

Percival Lowell was quite the man, according to Space. Born to a prominent East Coast family in 1855, he had money, status, name recognition, and intelligence in spades, and he worked in various careers (sometimes at the same time), but astronomy was never far from his mind. Thanks to wishful thinking and/or faulty equipment, he was able to "see" things on Venus and Mars that other astronomers couldn't see, some of which led him to (falsely) conclude that there could be intelligent life on the Red Planet.

By the turn of the century, he'd become convinced that there was a ninth planet (only eight were known at the time) beyond the orbits of Neptune and Venus, exerting its own gravitational influence on the orbits of those two planets. Night after night, for years, Lowell and his team searched the spot in the sky where they thought the ninth planet could be. Unfortunately, Lowell died in 1916 before his team found anything conclusive.

Clyde Tombaugh actually found it

In many ways, Clyde Tombaugh was the opposite of Percival Lowell. The latter was born with a silver spoon in his mouth on the East Coast, the former born to a hardscrabble farm family in the Midwest. Too poor to attend college or purchase telescopes, the young lad with an interest in astronomy simply built his own, according to the Academy of Achievement. In order to mitigate the effects of air currents and humidity on his equipment, Tombaugh hand-dug a ditch and put his telescopes in there, according to the book, "Out of the Darkness, the Planet Pluto." As an added bonus, the family also used the ditch as a root cellar.

By the 1930s, having proved himself as an astronomer and now working for the Lowell Observatory (named for, you guessed it, Percival Lowell), Tombaugh set about to actually finding Pluto, looking in the sky night after night for where Pluto was supposed to be and comparing notes. He found it. "I came to one place where it actually was, turned to the next field, there it was. Instantly, I knew I had a planet beyond the orbit of Neptune. That was the most instantaneous thrill you can imagine. It just electrified me!," he said (per the Academy of Achievement).

A tween girl named it

Nobody specifically asked Venetia Burney to name Pluto, but when she suggested the idea one spring morning, her family — who had the status and wherewithal to make big things happen — got the ball rolling (per NASA).

Venetia was born into a family of prominent British academics, her father a theologian and her grandfather an important figure at Oxford. Not long after the British papers announced that a ninth planet had been discovered, Venetia, at the time 11 years old, suggested Pluto. "For some reason, after a short pause, I said, 'Why not call it Pluto?' I did know, I was fairly familiar with Greek and Roman legends from various children's books that I had read, and of course, I did know about the solar system and the names the other planets have," she said (per NASA).

It might have been an off-the-cuff remark that went nowhere had Venetia been born into any other family. But her grandfather had friends in high places (many were astronomers), and soon, phone calls were made, and eventually, the new planet was named Pluto, and Venetia got the credit. For her efforts, she was given £5 (via EarthSky), which is worth about $6.50 at current exchange rates.

Who was Pluto (the god) anyway?

All of the planets in the solar system (save for Earth), and most of their moons, are named for the Roman gods. Or, more accurately, in English, we're calling them by the English transliteration of a Roman name for a Greek god (more or less; the relationship between ancient Roman and Greek religion is complicated).

Pluto was the Roman version of Hades, according to Mythopedia. Both gods ruled the underworld, but it bears noting that the underworld in this context isn't the equivalent of hell — which is to say, a place of eternal torment — but rather the place where the dead go. Similarly, neither Pluto nor Hades was an evil entity bent on punishing or torturing the people who went there. Pluto was not particularly evil, as gods go, although he did abduct a woman (Proserpina, depicted above), but there's considerably more to the story.

Since Pluto's abode was in the dark and gloom under the ground, it makes sense that he would share the name with a distant planet orbiting the sun, way out in the farthest reaches of the solar system.

What does the Disney dog have to do with any of this?

The Disney character named Pluto first appeared in 1930, according to the official fan club of the Walt Disney Company, D23. The two things can't have been coincidental, right?

Actually, probably not, although it's difficult to say for certain. First, it bears noting that the version of Pluto we all know and love evolved over time. It took a few iterations over a few months until Pluto, who doesn't speak and doesn't wear clothes, became who he is now. As for his name, Disney animator Ben Sharpsteen (via Comic Book Realm) wasn't sure if the newly-discovered planet played a role in naming the character. "We thought the name [Rover] was too common, so we had to look for something else. [...] We changed it to Pluto the Pup, [...] but I don't honestly remember why," he said.

However, Walt Disney himself may have been keen to see the pup named for the newly-discovered planet. According to the book "The Case for Pluto: How a Little Planet Made a Big Difference," it was indeed Walt Disney who saw to it that the dog was named for the planet (via Publishers Weekly).