Who gets a planet next? (Image: Image Broker/REX)

Planet-lovers, cast your votes. For the first time, the international organisation in charge of naming cosmic objects is asking the public to name planets found outside our solar system.

This week the International Astronomical Union (IAU) announced the NameExoWorlds contest, which will attempt to crowd-source official names for 20 to 30 exoplanets. The winning names will be announced in August 2015.

So far, astronomers have discovered more than 1800 exoplanets, including many that inspire visions of alien landscapes and possibly life. But the formal names for these planets, such as OGLE-05-390L b, HD 69830 d and PSR 1257 12 c, have been less than inspiring, prompting calls from astronomers and the public for more approachable monikers.


Last year, space outreach start-up Uwingu launched a website in which the public could submit names for exoplanets and vote on their favourites – for a fee. Submitting a suggestion costs $4.99 and voting costs 99 cents. Although the money goes towards research and education, the effort ran afoul of the IAU, which said planet names are not for sale.

Xena and Vulcan

Since 1919, the organisation has had the final word on the official names of planets, moons and asteroids in our solar system. The group follows strict rules and has often turned a deaf ear to any whimsical nomenclature scientists have used among themselves. For instance, the dwarf planet famous for ousting Pluto as a planet was initially called Xena by its discoverers, but was formally dubbed Eris by the IAU.

The organisation does accept suggestions from the scientists who discover new objects, but can overrule them. Last year, astronomers who found two new moons around Pluto put their names up to a public vote. The popular choice for one was Vulcan, after the Roman god and fictional Star Trek world. But the IAU vetoed the suggestion, citing a violation of its naming guidelines.

In the wake of a public outcry, the IAU asked the public to submit name ideas for celestial bodies both in our system and in the wider galaxy – although they have to follow a set of rules. Now the group has outlined an official process for naming exoplanets, and has partnered with the citizen science organisation Zooniverse to make it happen.

“We see this as a natural extension of the IAU’s strategy,” says IAU spokesman Lars Lindberg Christensen. “The IAU has supported the contribution of the general public in naming various solar system objects, but it took some time to find out how to deal with the complexity and magnitude of a global naming process.”

No guarantees

To kick things off, the IAU has created a list of 305 well-studied exoplanets. Starting in September, astronomy clubs and non-profit organisations will be able to register at a website and between them select 20 to 30 of these worlds to name. Each group will then be allowed to submit a name for one of these exoplanets, following the IAU’s naming rules. Once the suggestions are collected, they will be open to a public vote. The IAU will still have the final say, and will announce the results at its next general assembly in Hawaii in August 2015.

In case you’re wondering, names must be copyright-free, which may rule out calling a planet Alderaan or Westeros, for example. The IAU guidelines say names must be free for public use and “not subject to copyright royalties, as could be the case for names created in fiction works, like books, plays, movies, etc”.

But not everyone is happy. “To my eye, it’s just more IAU elitism,” says astronomer and Uwingu co-founder Alan Stern. “Uwingu’s model is in our view far superior – people can directly name planets around other stars, with no one having to approve the choices. With 100 billion-plus planets in the galaxy, why bother with committees of elites telling people what they do and don’t approve of?”

There are also questions about the planets the IAU is prioritising. The 305 worlds on the initial list were all discovered before 2009, which means the list excludes all the planets discovered by NASA’s Kepler space telescope. But the list does includes Gliese 581 d, which may not actually exist.

“There are no guarantees that all of the 305 exoplanets in this list will stand the test of time,” says Christensen. “Science changes all the time, and these objects are notoriously hard to detect. So changes to the list at a later stage are not impossible, and possibly Gliese 581 d could be such a case. For now, after careful considerations, it remains on the list although its existence is disputed.”