According to Wikipedia, "On 20 January 2016, researchers Konstantin Batygin and Michael E. Brown at Caltech announced calculation-based evidence of a massive ninth planet in the Solar System."

If visual evidence or another researcher confirms the existence of Planet Nine, does the actual discovery warrant naming rights, or would this go to our Caltech friends?

I know from this question's answer, that:

"Since the beginning of the 20th century the IAU is setting the standards for naming celestial bodies including planets. However, the IAU doesn't set the names, it only sets the standards."

Does the 'discoverer,' or the 'confirmer' get to name (theoretical) Planet Nine?

  • 1
    $\begingroup$ But can there even be a ninth "planet"? It's not going to have cleared it's orbital. $\endgroup$ Mar 4, 2016 at 3:04
  • $\begingroup$ @LorenPechtel - I don't know; I am only going from what I can find. It appears to have an enormous orbit, and dimensions about the size of 2x Earth - speculatively. $\endgroup$
    – Mikey
    Mar 4, 2016 at 4:41
  • $\begingroup$ @LorenPechtel - I just don't know what "it's not going to have cleared it's orbital," means. What I'm reading is that this calculation-based possible planet orbits, although mostly beyond the Kuiper belt. Not trying to be argumentative, just trying to see what you mean $\endgroup$
    – Mikey
    Mar 4, 2016 at 4:45
  • $\begingroup$ Planets are bodies massive enough to be round, orbit the sun and have cleared the other material from their orbit. (This is why Pluto got demoted--it's orbit isn't cleared, it's really just one of the bigger bodies in the orbit.) Something far beyond Pluto can't possibly have cleared it's orbit even if it's far more massive than Pluto--and hence can't be a planet. $\endgroup$ Mar 4, 2016 at 4:53
  • $\begingroup$ The discovery of something like a super earth in the outer Solar System that has not cleared its orbit will reopen the planet definition argument. There will be a strong case that a substantial body qualifies as something other than a dwarf planet. So it will have to be in a new category of its own or the definition of planet will have to change again. $\endgroup$ Mar 4, 2016 at 20:16

3 Answers 3


The cited answer is correct insofar as the IAU is not the body that makes names of celestial bodies official. However, it's authority is implicit because it is recognized by the astronomical community and the public as the foremost authority on astronomical naming, and thus the names the IAU adopts are the ones most commonly used in the scientific community (excluding objects referred to by their catalog numbers).

From one of their information pdfs:

The IAU has been the official arbiter of planetary and satellite naming since its inception in 1919. The IAU’s decisions are officially adopted by the nearly 11 000 professional astronomers who are its members, coming from more than 90 countries.

. . .

The IAU does not consider itself as having a monopoly on the naming of celestial objects — anyone can in theory adopt names the way they choose. 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).

The IAU may reach out to the public for naming suggestions, or it may taken case-by-case suggestions by individuals. So while Batygin and Brown can call the ninth planet whatever they want - they've informally referred to it as "Phattie" - public consensus will largely rest on the results of the IAU's decision, which could, of course, end up taking a suggestion of the pair.

Anyone can come up with a suggestion, although sometimes that's a terrible idea.

  • $\begingroup$ That it is called Phattie is sweet, but that it was mistaken by the NY Times as "Fatty," also makes me laugh <- but not in a mean-spirited way. $\endgroup$
    – Mikey
    Mar 4, 2016 at 1:57
  • $\begingroup$ "Fattie" is my nickname :) $\endgroup$
    – Fattie
    Nov 5, 2016 at 17:00

This would probably be a unique situation. Never in the era of the IAU has the existence of a space body been predicted prior to discovery.

The standard rule is that priority in naming goes to the team that discovers an object. In the scenario you describe, discovery would mean locating the object and determining its orbit. The statistical evidence for a planet nine is interesting, but far from overwhelming, and the team cannot be said to have discovered a planet.

However as this would be a unique situation, the IAU may choose to ignore its own protocols, and to consult more widely than normal, to seek a consensus among astronomers on the name.

  • 2
    $\begingroup$ "Never in the era of the IAU has the existence of a space body been predicted prior to discovery." The IAU was founded before the discovery of Pluto. All kinds of people had predicted that Pluto should exist -- perhaps not precisely enough? $\endgroup$ Mar 4, 2016 at 3:21
  • $\begingroup$ I would disagree. There was a prediction of a "planet X" that was causing perturbations of the orbits of Uranus and Neptune. But this was not a prediction of the existence of Pluto, which is much to small to have been planet X, and more accurate analysis of the orbit of Uranus shows that there is no anomaly. $\endgroup$
    – James K
    Mar 5, 2016 at 17:15
  • $\begingroup$ That's what I meant by "perhaps not precisely enough?" $\endgroup$ Mar 5, 2016 at 17:19

There will be a complex system of voting to decide on the best name, and the suggestions will come from worldwide sources amidst a media frenzy for a while, the media will sensationalize the naming of the planet.

It may be a 9 year old girl from a school than names a new planet if it is found.

Planet nine will probably be the place holder name for a while because it sounds ok, unless the media quotes another famous source who suggests a good name. The media will play a large part on publicising all the suggested names and the naming competition, so it's very much an astronomy PR game.

Probably the name of another planet would not become official for a good many years after it's discovery.

the story will perhaps be similar to the naming of Pluto:



You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .