The Lingo of Pluto: New Horizons, New Words

When the space probe New Horizons was launched from Cape Canaveral on January 19, 2006, Pluto was still classified as our solar system's ninth planet, and our clearest picture of it was a blurry blob. Nine and a half years and three billion miles later, Pluto—now demoted to "dwarf planet" status—has come into startlingly sharp focus, thanks to the first images and data received from the probe last week. As we learn more about this distant cousin of Earth, we're also expanding our linguistic horizons. Here's a closer look at some of the words and names in the Plutonian news.

Pluto. The most distant planet-like object in our solar system—called "Planet X" when its existence was only speculative—was discovered on February 18, 1930, by Clyde Tombaugh, a 23-year-old amateur astronomer using the telescope at the Lowell Observatory in Flagstaff, Arizona. The observatory, founded by Percival Lowell (of the patrician Boston Lowells) and later run by his widow, Constance Lowell, had the right to name the new celestial object; it received more than 1,000 suggestions, including several from Constance Lowell herself. ("Percival" and "Constance" were high on her list.) The winning submission came from an 11-year-old English girl, Venetia Burney, who was interested in classical mythology: Pluto is the name of the Greek god of the underworld, an apt association for a planet (or dwarf planet) in near-perpetual shade. It probably pleased Mrs. Lowell that the first two letters of "Pluto" were the initials of her late husband.

Young Venetia was awarded £5—the equivalent of today's $450—for her winning submission.

In keeping with a tradition of naming elements after newly discovered planets, Pluto lent its name in 1941 to the element plutonium. (New Horizons ' electricity source is 24 pounds of plutonium pellets.) The planet may also have inspired Walt Disney when he named Mickey Mouse's pet dog, who made his debut as Pluto the Pup in Moose Hunt, a cartoon released in 1931, when the world was still captivated by Pluto-mania. However, Disney animators never officially confirmed this theory.

These Plutos are only tangentially related to the pluto- in plutocracy (government by the wealthy). The confusion is easy to understand: as etymology blogger John Kelly points out, Ploutōn is the name of the Greek god of the underworld, and Ploutos is the name of the Greek god of wealth.

"Pluto" has been imported into many non-English languages, but not all. Japanese, Chinese, Korean, Vietnamese, Hindi, and Maori are among the languages that substitute names of indigenous gods of the underworld—for example, "Yama" in Hindi.

Charon. Pluto's primary moon shares a name with the ferryman to the underworld of Greek myth, but that's a lucky coincidence. The moon was discovered in 1978 by an American astronomer, James Christy, who proposed a scientific-sounding version of his wife Charlene's nickname, "Char." Partly out of respect for Christy and partly as an in-joke among space scientists, Pluto's moon is pronounced with an initial sh sound: Sharon. The Greek pronunciation, with an initial k sound, is often preferred by scientists outside the U.S.

Plutoed. In August 2006, the International Astronomical Union (IAU) passed a resolution that effectively demoted Pluto because it does not "clear the neighborhood" around its orbit. (Its mass is too small.) In January 2007, the American Dialect Society (ADS) chose plutoed as its word of the year for 2006. "To pluto is to demote or devalue something," declared the society's press release. CNN called the ADS vote "Pluto's revenge." But this month's new information about Pluto has "resurrected the debate" about Pluto's status, reported The Guardian. Charles Bolden, NASA's chief administrator, told the paper "he hoped the official classification would be reconsidered. 'I call it a planet, but I'm not the rule maker,' he said."

Flyby (also fly-by). New Horizons' route past Pluto was universally dubbed a flyby. The word, a shorter and catchier way of expressing "flight past," first appeared in the pre-spaceflight year 1953, when an issue of a helicopter manufacturer's journal referred to "spectacular aerial flybys by jet planes." Since then, the word has mostly been associated with space flight; the OED defines it as "a close approach to a celestial body for the purpose of observation" or "a spacecraft that makes such an approach."

Ralph, Alice, REX, SWAP, LORRI, and PEPSSI. There are seven scientific instruments on board New Horizons. Ralph is the visible and infrared imager/spectrometer; it's coupled with an ultraviolet imaging spectrometer dubbed Alice. The names are a nod to the 1950s television sitcom "The Honeymooners," in which Ralph Gleason's character, Ralph Kramden, frequently mock-threatened his wife by saying "To the moon, Alice!" ("Our principal investigator has a great sense of humor," Lisa Hardaway, the engineer who led the development of Ralph, told a reporter for Space News.) Four of the other instruments have acronym names: REX (Radio science Experiment), LORRI (Long Range Reconnaissance Imager), SWAP (Solar Wind Around Pluto), and PEPSSI (Pluto Energetic Particle Spectrometer Science Investigation).

Until recently, the seventh instrument had a merely descriptive name—Student Dust Counter—but it's been renamed Venetia in honor of the English schoolgirl who named Pluto.

Mordor, Cthuhlu, Meng-Po'o, and Tombaugh Regio. What sounds like the title of a Jorge Luis Borges short story is in fact a partial list of informal names for newly discovered features on Pluto and Charon. (Formal names must be approved by the IAU, but as one project scientist tweeted, "Cannot just say 'that dark spot.' 'No I meant that dark spot.'") Many of them are drawn from "your darkest imaginings," as the science blog io9 put it—and consistent with the established names of Pluto's moons, including Styx (in Greek myth, the river of death), Cerberus (the three-headed hellhound that guards the underworld), and Nix (the Greek goddess of night). The new names depart from classical mythology and enter fictional realms: The dark area at Charon's polar region, for example, has been tagged Mordor, from the wasteland in J.R.R. Tolkien's Lord of the Rings trilogy. On Pluto itself, an area originally dubbed "the whale" is now called Cthuhlu, after the fictional deity invented by H.P. Lovecraft; and Meng Po'o is the Buddhist "lady of forgetfulness." An exception to the pattern is the Tombaugh Regio—literally "region of Tombaugh"—which honors Pluto's discoverer, Clyde Tombaugh. For a long list of Plutonian names suggested by the public, see the Our Pluto discussion forum.

Pluto Pals (or Plutokids): Membership in this group—officially, the New Horizons Kids Club—is restricted to kids who were born on January 19, 2006 (the day of the New Horizons launch) or who celebrated their tenth birthday on that day. The search for eligible kids was announced by New Horizons principal investigator Dr. Alan Sterns, of the Johns Hopkins Applied Physics Laboratory, in January 2007, afterNew Horizons passed Jupiter. Some Pluto Pals traveled with their families to Maryland last week, to watch the flyby from the mission's home base.

After passing within 7,800 miles of Pluto's surface on July 14, New Horizons is already two million miles beyond it, headed for the Kuiper belt, a distant region of small, icy bodies. Meanwhile, data and images from the Pluto flyby will continue to pulse earthward for the next 16 months. By the end of 2016, we may be contemplating an entirely new nomenclature and vocabulary for this remote yet increasingly familiar and fascinating neighbor.