Remember last week when PopSci told you about a "people's choice" contest to name the planet orbiting the Alpha Centauri star system? And the International Astronomical Union had cried foul, saying the paid contest had no bearing on the names? Well, it's not really that simple. You can call a star or a planet whatever you want, and even pay to nominate your favorite; it just might not matter to anyone else.
Here's the story: Last fall, astronomers spotted a planet orbiting Alpha Centauri B, the nearest star system to our own. This was exciting for a lot of astronomers, fans of science fiction and members of the public, for whom the Alpha Centauri system looms large in the imagination. So this spring, a space education company called Uwingu (it means "sky" in Swahili) started a contest to ask people for a name, something more exciting than Alpha Centauri Bb. You can pay $4.99 to nominate a planetary appellation, or pay $0.99 to vote. The top three are Caleo, Rakhat and Amara - the last of which is the name of some guy's fiance, proposed in her honor.
The thing is, the contest winner will not be the planet's officially recognized astronomical name, used by professional astronomers in their research papers, noted in textbooks and otherwise lofted into the scientific canon. It won't have the weight of an official title like Jupiter, for instance.
There is no official list, book of names or other registry of exoplanet titles and designations. There's not even an official list of star names - there are many celestial catalogs, each recording the same stars and giving them different names. Astronomers use general guidelines according to the catalog they're using, and the IAU unofficially recognizes these.
"There's definitely a place for popular names and informal names; sometimes they can make it into the literature, like maybe a well-known star like Polaris," said astronomer Jason T. Wright of Penn State, an exoplanet researcher and blogger. "I know a lot of people are concerned that opening it up to popular names could lead to more confusion, but I am neutral. I think it's great if people get really interested in exoplanets."
The IAU, which is an international organization of astronomers who agree on things like names of celestial objects, last week pointed out (rather pointedly) that Uwingu's contest is technically meaningless. The IAU said it and its members are the sole arbiters of these things, and Uwingu voters will not christen the planet in the global astronomical record. But neither will the IAU, at least not until it drafts some new rules. That was unclear from their own statement, and Uwingu, Wright and others took issue with that.
The IAU does not even have an officially recognized definition for exoplanets, Wright pointed out. The IAU does define certain things, most famously PLANET - as in one located in this solar system - which led to the demotion of now dwarf planet Pluto. It also operates committees that agree on accepted names for locations on Mars and on the moon.
"The Uwingu project in question does not promise ‘rights to name exoplanets.' It is compiling a database of names that astronomers, including those in charge of nomenclature at the IAU, might use to name exoplanets," Wright wrote on his blog.
Uwingu is operated by several prominent astronomers, including Alan Stern of the Southwest Research Institute, a major proponent of crowdsourcing and also the chief investigator on the New Horizons mission to non-planet Pluto. And although the current contest has no bearing on final names, there is certainly precedent for this sort of thing. In our solar system, planets and their moons are named after Roman and related Greek gods, but not initally: Have you ever heard of George's Star? William Herschel chose this name (the Latin version is Georgium Sidus) for Uranus, after he discovered the planet in 1781. He wanted to honor his patron, King George III. (The name didn't stick.)
Wright said he would prefer the IAU clarify what it has and hasn't done about naming planets, but he doesn't think there's a need for an official exoplanet designation process. Astronomers generally follow an unofficial scheme, recognized by the IAU, of designating planets with an alphabetical system based on the name of their star. The star is technically the first member of the system, so there's no planet "a." For instance, the star Kepler-22 has an Earth-sized planet orbiting it, and its name is Kepler-22b. The star HD40307 is accompanied by planets HD40307 b, c, d (probably e and f) and g, and so on throughout the cosmos.
"A designation follows some scheme to name them all according to a catalog, so that no matter what you find in the future, your designation can accommodate it," Wright explained. "Stars can have names and technical designations."
Like, for instance, Polaris. Everyone has seen the brightest star in the Little Dipper, one of the brightest in the night sky. To most North Americans, it's just the North Star. It's also known as the Lodestar or the Guiding Star. In astronomical catalogs it's HD8890, or FK5 907, or HIP 11767, or a Ursa Minoris, and so on. All of these names refer to the same thing.
And so it could be with Alpha Centauri Bb. If you want to vote, for a lark, you can do it here.