Pluto, we have a problem: Some geographical names may not fly on official maps

Pluto, we have a problem: Some geographical names may not fly on official maps
The heart-shaped area that’s prominent in this New Horizons picture of Pluto is known as Tombaugh Regio. (Credit: NASA / JHUAPL / SwRI)

Some of the best-known names on Pluto — ranging from the Sputnik plains to the Hillary and Norgay mountains and the dark Cthulhu Regio — may never appear on the International Astronomical Union’s maps, due to a tiff over terminology.

Those are just a few of the informal names that have raised questions from members of the IAU panel charged with approving the nomenclature for the dwarf planet’s geographical features. The names were selected by the team behind NASA’s New Horizons mission to Pluto after a months-long online naming campaign at

The group’s chair, Rita Schulz of the European Space Agency, said the New Horizons team has not yet submitted a formal proposal for naming features on Pluto and its moons.

“Usually, there are always some features for which this process goes rather fast, some for which more checks and balances are required (which then takes a bit longer) and there are usually also some names or descriptors that cannot be approved and need to be replaced by others,” she told GeekWire in an email.

On the other side of the net, Mark Showalter of the SETI Institute, who headed up the campaign and is a member of the New Horizons team, said he was looking for additional guidance from the IAU.

“We haven’t gotten any official response yet,” Showalter told GeekWire. He said the informal labels were “great names, and we’ll do whatever we can to encourage them.”

A close-up of Pluto’s surface shows a dark area called Cthulhu Regio at left, mountains that have been nicknamed Hillary Montes at center, and a flat region unofficially known as Sputnik Planum at right. Members of an IAU panel have raised questions about those names. (Credit: NASA / JHUAPL / SwRI)

One sure winner is Tombaugh Regio, the bright heart-shaped region that dominates the best pictures taken by the New Horizons probe during its July 14 flyby. The name pays tribute to Clyde Tombaugh, the Illinois-born astronomer who discovered Pluto in 1930. Schulz said her working group “could approve this name right away, as we have pre-discussed it.”

Other names will face tougher sledding. Months ago, the IAU said it would not consider the suggestions that were inspired by historic spacecraft or space missions; or by explorers of the Earth, air and seas; or by authors, artists, directors and producers of exploration fiction. Such names should be excluded because “these themes have already been used on Mercury, Venus and Mars,” the IAU said.

That could rule out Viking Terra, Columbia Colles, Challenger Colles and Soyuz Colles, Sputnik Planum, Hillary Montes and Norgay Montes (touted as the first extraterrestrial feature bearing the name of a Nepali). Clarke Mons and Kubrick Mons might have to be crossed off the maps of Charon, Pluto’s biggest moon.

This annotated map shows the initial, informal names being used by the New Horizons team for features and regions on Pluto’s surface. For a larger version, visit (Credit:

The categories that have been cleared for takeoff include mythological names for the underworld and its denizens (including dwarfs), as well as writers, scientists and engineers associated with Pluto and the Kuiper Belt. For Charon, fictional people, places and vessels associated with exploration and space would be OK. There are also pre-approved categories for Pluto’s smaller moons: river gods for Styx, deities of the night for Nix, famous dog names for Kerberos, and legendary serpents and dragons for Hydra.

Within those categories, the IAU might still pick and choose: For example, some of the working group’s members have raised questions about Cthulhu Regio, the New Horizons team’s nickname for a dark whale-shaped region along Pluto’s equator. That’s because the fictional monster known as Cthulhu was created by H.P. Lovecraft, who espoused racist and anti-Semitic views in some of his other writings.

Showalter acknowledged that he had heard about the pushback over Cthulhu, but pointed out that the IAU already approved naming a crater on Mercury after Lovecraft. He also argued that the character has transcended its creator.

“It’s a literary icon from the world of horror fiction, and it’s moved beyond Lovecraft himself,” Showalter said. “Fictional creations are not the same thing as the horrible things that may have been done by the people who created them.”

This map shows the informal names used by the New Horizons team for features on Charon, Pluto’s largest moon. Check for larger versions of the map. (Credit:

Spock, Kirk and Vader Crater also could be controversial, even though those science-fiction icons fit nicely within the IAU’s categories for features on Charon. During a series of interviews over the past month, Schulz voiced concern that some names may not be enduring enough to merit recognition. “We must be sure that a few generations after us, no one asks, ‘How could they name it for somebody no one knows?’” the Berliner Morgenpost quoted her as saying last week.

The IAU also wants to make sure the names on Pluto and its moons reflect a wide variety of the planet’s cultures, and not just Hollywood icons.

Does it matter what the IAU thinks? New Horizons’ principal investigator, Alan Stern, doesn’t think so. He has lambasted the organization for the way it treated Pluto, and got under the IAU’s skin by setting up informal naming systems for extrasolar planets and Martian craters. By some accounts, those dust-ups have added to the friction over New Horizons’ nicknames.

It’s not unprecedented to see nicknames take more of the spotlight than the IAU’s approved names. For example, the mountain being explored by the Curiosity rover on Mars is known more widely as Mount Sharp (NASA’s unofficial name) than as Aeolis Mons (the IAU’s official name). And the features on Curiosity’s route, such as Yellowknife Bay and Marias Pass, are routinely nicknamed without consulting the IAU. So who knows? Maybe someday we’ll be skating over Pluto’s Sputnik Plain after all.

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