Welcome to the excellently weird world of informal naming systems: here’s how we’re naming all the newly-discovered places on Pluto after Cthulhu, Balrog, Meng-p’o, and other dwellers from the underworld.


When exploring a whole new world, it’s important to come up with a shared vocabulary for naming the new geography. As mission scientist and (“wow^wow” image-teaser) Kimberly EnnicoSmith explains:


While the always-enchanting Randall Munroe of xkcd has his own naming suggestions, NASA had a different idea. After opening the naming scheme to a public vote earlier this year, the features on Pluto are all being informally named for preliminary discussions after creatures related to underworld mythologies. The names are somewhat following the popular vote, although the scientists are certainly sneaking in a few of their favourite dark lords to label locations.

Names we’ve used so far:

Meng-p’o : Buddhist goddess of forgetfulness and amnesia, tasked in the underworld with ensuring reincarnated souls will not remember their previous lives.

: Buddhist goddess of forgetfulness and amnesia, tasked in the underworld with ensuring reincarnated souls will not remember their previous lives. Cthulhu : an elder god from HP Lovecraft mixing features of man, octopus, and dragon.



: an elder god from HP Lovecraft mixing features of man, octopus, and dragon. Krun : one of five Mandaean lords of the underworld, nicknamed “Mountain-of-Flesh”



: one of five Mandaean lords of the underworld, nicknamed “Mountain-of-Flesh” Ala : Odianai goddess of earth, morality, fertility, and creativity.



: Odianai goddess of earth, morality, fertility, and creativity. Balrog : monster able to shroud itself in fire, darkness, and shadow, and the apparent killer of Gandalf the Grey in the Lord of the Rings.

: monster able to shroud itself in fire, darkness, and shadow, and the apparent killer of Gandalf the Grey in the Lord of the Rings. Vucub-Came and Hun-Came: Mayan hero-twins and death gods

You can check out the full list of yet-to-be-assigned names here.

This is far more badass than the naming scheme foisted on this summer’s other dwarf planet: all new features on Ceres are related to agriculture. However, it does lead to a few interesting crossovers: a surprising number of agricultural goddesses also dabble in death.

Meanwhile, objects in the rest of the system each get their own themes. The theme of the largest moon, Charon, are still to be announced. The ferryman for the dead will carry features having something to do with exploration, although it’s still to be announced if that will be exploration destinations (which could get confusingly meta if we name locations after the Pluto flyby!), exploration vessels, or the explorers themselves.

Each of the mini-moons have their own already-announced themes. Styx, river the dead cross into the underworld, will be collecting river gods. Nix, personification of the night itself, will take on all the other night deities. Kerbeos, the hellhound of Hades, will be collecting canines from literature, mythology, and history. Finally, the many-headed Hydra will take on legendary serpents and dragons for its naming scheme.


As for making these names official, that’s up to Pluto’s nemesis, the International Astronomical Union (IAU). Now that a (dwarf) planetary theme has been selected, all proposed names go through an IAU task group for approval. Hopefully, they won’t kill all our fun and soon Cthulu will find his way into the official list of formal planetary features.

The New Horizons probe completed its closest approach of the Pluto-Charon system early this morning. Join us on io9 at 8:30pm ET/5:30pm PT tonight as we live-blog the wait for the daring probe’s first call home after the encounter.


Updates on July 15, 2015:

The now-iconic heart of Pluto has an official informal name, Tombaugh Regio after Clyde Tombaugh, the discoverer of Pluto. Admittedly, its new name only matches the theme in that its namesake is dead.


Mordor, the dark polar area, is the first named location on Charon. Mordor is a location in the fantasy series The Lord of the Rings, a place significant for its trio of encompassing mountain ranges that both protected the region from invasion and kept those within from escaping, and for housing the One-Ring-destroying volcano Orodruin. I’m not quite sure what that makes the theme from the three options — places you don’t want to explore?


Between Balrog on Pluto and Mordor on Charon, I’m wondering who the massive Lord of the Rings fan is on the Geology and Geophysics science team!

Updates on July 19, 2015:


Landforms in Tombaugh Regio are earning names: the Norgay mountains and Sputnick plains. Image credit: NASA/JHUAPL/SwRI annotated by Mika McKinnon

The Tombaugh Regio is getting more detailed placenames, this time with an explorers theme. The tall icy mountains in the southwest are now Norgay Montes, named for sherpa Tenzing Norgay, who summited Mount Everest with Edmund Hillary in 1953. The oddly-textured plains extending from the south into the interior are Sputnik Planum, named for the original space explorer and first artificial satellite, Sputnik 1.


Top image: Informal names on Pluto as of July 14, 2015 Base image: Björn Jónsson using dating from NASA/JHU-APL/SwRI, Annotated by Mika McKinnon using data from Emily Lakdawalla