Amidst all the excitement of seeing Pluto’s unique features for the first time, NASA researchers have been using unofficial names to talk science until official terms come down the pipeline.

On July 8th we showed you a picture of Pluto’s odd equator, containing two features that NASA scientists at the time had dubbed “the whale” and “the donut.” Here is the same image again, but this time with some more plausible (but still preliminary) names that Mark Showalter (SETI), organizer of the OurPluto campaign to solicit Pluto-feature names from the public, put together for a July 14th science presentation. (Most of these names were captured in a photo taken by Emily Lakdawalla and posted to Twitter.) Instead of “the whale,” it’s Cthulhu that’s lurking at Pluto’s equator, with a Balrog and a gaggle of underworld gods and beings as neighbors.

Preliminary names for Pluto features
Preliminary names shown on the pre-flyby map of Pluto. (Later image releases will result in sharper maps and more precise feature classifications and names.)

The center of the image shows Pluto’s “heart” and the names that have been informally attached to that region. The photo below reveals a close-up of the Sputnik Planum taken during the flyby.

Broad plain dubbed Sputnik Planum
This captivating photo of the vast, craterless plain that lies in the center-left of Pluto’s heart has been informally named the Sputnik Planum. The heart itself has also been unofficially named Tombaugh Regio, to honor Pluto's discoverer, Clyde Tombaugh.

Here is a close-up of the Norgay Montes region:


These preliminary names come from the list compiled during the OurPluto naming campaign, but so far the International Astronomical Union (IAU) has not approved them (or any others).

The IAU is very precise about how they name planetary features. Similar to how biological beings are divided into kingdoms, classes, and species, so too are solar system features (along with stars and galaxies) grouped and classified, then named according to an overarching theme. For example, craters 60 km or greater on Mars are named after deceased scientists and explorers, as well as writers who wrote about the Martian planet. Smaller Martian craters are named after cities with populations less than 100,000. Here's the full list of the IAU’s themes and conventions.

As such, until those studying Pluto can understand and classify Pluto’s features, the IAU will have to wait to properly group and approve names. However, according to Rita Schulz, chair of the IAU’s Working Group on Planetary System Nomenclature, the first name likely to come down the Pluto-naming pipeline will be the Tombaugh Regio — and it seems fitting to name Pluto’s heart after the world’s discoverer.


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