Name That Planet!

The naming of planets is informed by specific rules—so if you find a new world out there, here’s a crash course on the process.

If when peering through a telescope (or going over empirical data) you suddenly realize you’re coming upon a planet new to science, the first thing you should know is that you probably won’t be naming it after yourself, your dog or favorite rock star (this isn’t fossil hunting, you know).

Instead, you’ll want to get acquainted with the guidelines put forth by the International Astronomical Union (IAU). Founded in 1919, it has long-been granted charge to “promote and safeguard the science of astronomy in all its aspects through international cooperation.” Consisting of over 12,000 astronomers from 97 different countries, its authority is no joke—for example, all the debating once held about the planetary status of Pluto was ended once the IAU officially downgraded to a dwarf planet in 2006. In other words, the planet game is ruled by the IAU, case closed.

Knowing this, what’s a person to do when coming across an exoplanet? The distant worlds are turning up with frequency these days—so if you manage to find one, here’s some good news: The IAU isn’t going to dog you on the name…sort of.

The IAU site says that it “does not consider itself as having a monopoly on the naming of celestial objects — anyone can in theory adopt names the way they choose.”

But it also says: “However, given the publicity and emotional investment associated with these discoveries, worldwide recognition is important and the IAU offers its unique experience for the benefit of a successful public naming process (which must remain distinct, as in the past, from the scientific designation issues).”

In other words, you’re very welcome to follow their rules, which sticks to a scientific nomenclature consisting of a proper noun or abbreviation (sometimes with associated numbers) to be followed by a lowercase letter. Example: 75 Cet b—it’s a world orbiting the star 75 Ceti. The “b” indicates it’s a companion object (like a sidekick).

Then again, say a planet has been discovered via NASA’s Kepler space telescope—lots of those get named after the machine, like Kepler-30 d. Kepler found the star (it was named “Kepler-30”) and then spotted three planets in its orbit—which became Kepler-30 b, Kepler-30 c and -30 d.

Other suggestions from the IAU include not using “Names of pet animals,” “Names of individuals, places or events principally known for political, military or religious activities” or “Names of a purely or principally commercial nature”—and try to keep your appellations “Pronounceable (in some language)” and “Non-offensive.”

Furthermore, the IAU had recently sanctioned an exoplanet naming contest—and despite any of the names that may or may not have come about in conjunction with the competition, Executive Committee member and former General Secretary Thierry Montmerle recently responded to a Many Worlds column as such:

“We’ll see in the long term whether the names are caught up by the public in general, but in our opinion it will be more a matter of the future scientific interest of the objects themselves (exoplanets and/or stars) than of their public name.”

On the other hand, it gets tougher when finding something closer to home.

Remember when the dwarf planet Eris was known as Xena? A Kuiper-belt object (like Pluto), its discoverers originally named it after the main character of the TV show Xena: Warrior Princess —and its moon was named “Gabrielle,” as TV’s Xena had a sidekick by that moniker. However, the IAU must approve official names, and here the rules get tight. From the IAU website:

“Objects, including dwarf planets, far beyond the orbit of Neptune are expected to be given the name of a deity or figure related to creation; for example Makemake, the Polynesian creator of humanity and god of fertility, and Haumea, the Hawaiian goddess of fertility and childbirth….The IAU finally decides on the assignment of the name, priority given to the ones proposed by the discoverers.”

The finders of Eris (Mike Brown, Chad Trujillo, David Rabinowitz) weren’t being funny when they came up with Xena, as at the time Pluto was still considered the ninth planet—which could have meant Eris was to be designated the tenth planet, and the Roman numeral X means “10”—so they called it “Xena” until the IAU decided its classification. Once categorized as a mere dwarf planet, the discovers stuck to the rules and gave it its current name Eris (after the Greek goddess of chaos) and redubbed its moon Dysnomia (a mythological child of Eris).

Of course, should you somehow find an actual, full planet orbiting our sun, that will probably send the IAU into a tizzy, as it currently states “none appear likely in our Solar System”—but chances are you’d need to stick to Roman and Greek mythology if you did—for all except one (ahem, Earth) follow that theme.