Not 9, not 12, there are 8 planets only

The International Astronomical Union’s General Assembly have been voting, in fact they still are [for now], on the proposals for the definition of a planet listed here. And, as the BBC breaking news report put it “Pluto loses status as a planet” [breaking news? – Ed] and here. I’m trying to confirm the voting, but it seems proposal 5A was passed, and 5B was voted down.. which means, as suggested yesterday, we have lost Pluto.. Updated below Updated againThe definition of a planet

The IAU therefore resolves that planets and other bodies in our Solar System be defined into three distinct categories in the following way:

(1) A planet1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A dwarf planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects3 orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.


1The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
2An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
3These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

They’ve just voted to accept 6A.. 6B to follow has been voted down.

The IAU further resolves:

Pluto is a dwarf planet by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.

The following sentence is added to Resolution 6A:

This category is to be called “plutonian objects.”

Update 6B was voted down which means there is no name at present for the new category of trans-Neptunian objects.

More There’s an interesting aside to note about the voting today, or more particularly who oversaw the proceedings at the General Assembly, as detailed in this report from the Guardian

Jocelyn Bell Burnell, a specialist in neutron stars from Northern Ireland who oversaw the proceedings, urged those who might be “quite disappointed” about Pluto’s diminished status to look on the bright side.

“It could be argued that we are creating an umbrella called ‘planet’ under which the dwarf planets exist,” she said, drawing laughter by waving a stuffed Pluto of Walt Disney fame beneath a real umbrella.

Updated again

As renowned astronomer Jocelyn Bell Burnell, formerly of this parish (Northern Ireland) and currently the house patron of Burnell House at Cambridge House Grammar School in Ballymena, comforts Pluto *ahem* the BBC notes that there could be trouble ahead…

Is this the end of the matter?

Unlikely. The Principal Investigator on Nasa’s $700m New Horizons mission to Pluto has lambasted the decision to demote Pluto. Alan Stern told BBC News the decision was “embarrassing” and the criteria amounted to “sloppy science”. He said like-minded astronomers would try to get Pluto reinstated.

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  • Richard

    How do the Plutonians feel about this? Were they consulted? Outrageous!!!

  • Simon C

    You know, back in 1930, astrologers were falling over themselves to explain why the discovery of a new planet affected them not one whit. I’m really looking forward to seeing the contortions the fraudulent g*bsh*t*s go through to get out of this one…

  • circles

    I just feel sorry for Mickey Mouse!!!

  • SlugFest

    Does this change make us (well, me really) any closer to being the center of the universe?

  • Occasional Commentator

    Why the [breaking news? – Ed] in the post?

    It is breaking news because they’ve only voted for definite on it in the last few hours.

  • Pete Baker


    It’s just a note to signify how most, all I think, of the major media companies have reacted to the story.

  • Billy Pilgrim

    “Northern Ireland “not centre of universe” – scientists”

    Now that’d be controversial. That’d be a debate we Sluggerites could get our teeth into.

    But seriously: who the hell are we, as Earthlings, to start telling the Plutonians that theirs is not really a planet? Where’s the parity of esteem there? Who dares to speak out for the Plutonians?

    How would we like it if some boffins on Jupiter started casting aspersions on our own planetary status? Ah yes, we Earthlings are quite the big fellas, taking potshots at Pluto, when it’s only a little slip of a thing, and far, far away. You never hear scientists getting lippy about Saturn, do you? Hah, they know better.

    And more to the point, would someone please advise, quickly, whether Pluto is a Catholic or a Protestant planet? How the hell are we in NI to know where we stand on this issue otherwise?

  • Pete Baker

    I’ve added a little piece of info that might interest some, on the voting today and the person overseeing the proceedings – Jocelyn Bell Burnell

  • About bloody time is what I say. Pluto has been mascararding as a planet all these years. But now the mask has finally slipped. We now is it and its moon really is. Rocks. Now if we can get mecury’s bald head of the list we can get somewhere on this list business.

    What does this make exoplanets then

  • Rory

    It has nothing whatsoever to do with religious sectarianism, Billy Pilgrim. Pluto refused to rejoin the Commonwealth and accept the Queen as its head. Besides which, they support Arsenal.

  • Pete Baker


    Interesting point, and if you look at the previous post, one that was raised during the earlier debates [the video should still be there].

    In short, it doesn’t affect them. They were excluded from the remit of the definition under discussion.

  • Occasional Commentator

    What about Charon? It’s tempting to think that it’s a satellite of Pluto, and therefore not a dwarf planet. But Charon and Pluto actually orbit a point in between them that isn’t within either object. Therefore they are a pair of dwarf planets.

    Compare this with the Earth and the Moon, where the Moon (and the Earth) each orbit around a point which is close to, but distinct from, the centre of the earth. This point is still within the earth meaning the Moon is a proper satellite of the earth.

  • Keith M

    Do people actually find this kind of stuff interesting? For me it meets every definition of the word “academic”.

  • Crataegus


    Do people actually find this kind of stuff interesting.


    Let’s face it beats Paisley’s position on virtually anything, Jerry Adams’s sanctimonious babble, David Ford on voting systems. Lets face it about the few sparks of interest on the political front..

  • Greenflag

    ‘Let’s face it beats Paisley’s position’

    Now if only Paisley were a trans Neptunian the inner Solar System would be a less cantankerous place

  • Miss Fitz

    I was quite taken aback at the reason given on the news. They said that since Pluto is a dwarf, it doesnt have equal rights.

    Now, this may be a symptom of living here too long, but has anyone spoken to Monica? Not vertically or horizontally challenged, not short, not a ‘little planet’ but a very politically incorrect dwarf.
    On behalf of short people everywhere, I am outraged.

  • Crataegus

    Miss Fitz

    Its rough being a trans Neptunian object always left out in the cold.

  • inuit_goddess

    The Bastards! What right have they got to take away Pluto as a planet?

    Pluto has existed as the 9th Planet in the collective imagination of humanity for so long. Yet this undemocratic conglemoration of scientists now tells us that this beautiful, distant orb in the heavens is no longer worthy of the name Planet.

    Instead, they tell us, she is now merely to be a ‘Dwarf Planet’.

    All who love our friendly neighboring orbs and the sense of our earth, hurtling along through the void, accompanied by her sister planets, must protest.

    Pluto is a planet, and long may she live on in our imaginations, the princess of the furthermost outreaches our solar system.

  • Pete Baker

    Pluto always did seem a bit of a thug to me.. wandering around the solar system, trampling all over Neptune’s turf in his platform boots, pretending to be a planet with his mate Charon close at hand to back him up.. and not one, but two other moons in attendance.

    ’bout time he was taken down a peg or two..

  • inuit_goddess

    I disagree Sir! Would we accept such undemocratically imposed Drarfishness on any other of our friends?

    Let Pluto Live!

  • Pete Baker

    “undemocratically imposed”

    There were several votes taken on this, by the IAU, and they were all overseen by someone who was born here.

    You can call Pluto whatever you like… but the text-books will say it’s not one of the 8 planets of the solar system. ;op

  • Aislingeach

    More importantly, what are we going to teach the children about how to remember the planets? (Someone please think of the children!) I mean, I learned “My Very Educated Mother Just Served Us Nine Pickles” to get the planet names in order and they just destroyed the Pickle!!
    Okay, “…Just Served Us Nectarines.” “Nachos”? “Nothing”?

  • SlugFest

    Pluto will live on, no doubt. Remember when the Catholic church ousted St. Christopher (actually, neither do i … happily before my time … but i was taught so by Sister Ann)? The worldwide congregation simply ignored the church’s ruling on it — his medals are still sold, and you can find him on a number of cheezy cars — the Pinto, especially.

  • SlugFest

    Correction: you won’t actually find St. Christopher ON any car (at least i haven’t, though i lost the faith years ago) — you’d find a replica of him on the dashboard.

  • Pete Baker


    I like ‘Nothing’ as the alternative in that mnemonic.

    Could have been worse, though… you might have had to think up something for Ceres and Charon..


    Oh, Pluto’s still there… it’s just not a planet.

  • Aislingeach


    Being a Very Educated Mother myself, I ALSO prefer the idea that she serves them “nothing”!

    Let’em fetch for themselves…

  • Pete Baker


    Btw I’ve added a little something to the original post.

  • Pete Baker

    For anyone wondering what Russell Grant makes of it all [who would wonder about that? – Ed]

    Reuters has the answer

    “I personally am shaken not stirred,”

    *shakes head*

  • lovelyleitrim

    I’m just glad nobody interfered with Uranus.

  • Aislingeach

    And for those who do care what Russell Grant thinks. I have this to say:
    I’m a sceptical Scorpio; we don’t believe in astrology. Now pass your cuppa and I’ll read the tea leaves.

  • IJP

    A very sensible conclusion, albeit a reluctant one.

    I’d still be interested to know how Pluto ended up where Neptune “should be” according to the Titius-Bode law. There is still a lot to be uncovered out there – and I fear the outcomes will rarely be simple!

  • Pete Baker

    Should be, IJP?!?

    The fact that Neptune – an actual planet – isn’t where it ‘should be’ according to the Titius-Bode Law is fairly damaging to the idea that such a law exists..

    From Wikipedia

    When originally published, the law was satisfied by all the known planets — Mercury through Saturn — with a gap between the fourth and fifth planets. It was regarded as interesting, but of no great importance until the discovery of Uranus in 1781 which fit neatly into the series. Based on its new credibility, Bode urged a search for a fifth planet. Ceres, the largest of the asteroids in the Asteroid Belt, was found at the predicted position of the fifth planet. Bode’s law was then widely accepted until Neptune was discovered in 1846 and found not to satisfy it.

  • Crataegus


    I wouldn’t put too much faith in the Titius-Bode ‘rule’ As far as I remember it doesn’t work if applied to the moons of Uranus or indeed Jupiter.

  • IJP


    Of course, it is more than possible the T-B law is just plain wrong.

    However, it does seem remarkable that Pluto is pretty well exactly where Neptune “should” be.

    Throw in Uranus’ weird rotation and I’d say it’s odd-on you have something chaotic happening there since the formation of the solar system.

    To be honest, though, I was just trying to cheer Pluto up and make it feel important again. And you’ve just ruined it. Poor wee dwarf…

  • inuit_goddess

    BBC are reporting major backlash among scientific community over this! The Save Pluto campaign is barely beginning…

    Clearly such a campaign will need it’s own paramilitary wing to have real teeth, and it surely falls to us, here, in this province to provide such a wing.

    The Pluto Liberation Front anyone?

    The Pluto Peoples Party?

  • Miss Fitz

    Irish Plutonian Liberation Organisation?

  • Miss Fitz

    What got me was the way the scientists viewed this. You know, Pluto is only a dwarf, and if we let all the other dwarfs think that they can be planets, you dont know where it would end! So, the only way we can handle this is to put Pluto in its place, to rid the other pesky planets of any notion of joining the big boys.

    Yes Massah

  • Pete Baker

    “So, the only way we can handle this is to put Pluto in its place, to rid the other pesky planets of any notion of joining the big boys”

    Hmmm… putting Pluto in its place, certainly.

    But because it was never the planet those who discovered it thought it was. What’s happened is the righting of a wrong designation in 1930.

  • Miss Fitz

    Well, Pete, if I got this right, there is still no definitive descriptor of a planet?

    So, its not so much that they got it wrong in 1930, as they cannot allow other ‘lumps of rock and ice’ to be labelled as planets.

  • Pete Baker

    Resolution 5A set out the definition of a planet, Miss Fitz.

    That’s what the debate has been about.

    “(1) A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.”

    Pluto fails the definition on point (c)

  • Pete Baker

    Just to add, they did get it wrong in 1930.

    They were looking for a celestial body with a much larger mass.. and assumed Pluto was it.

  • Miss Fitz

    Thanks Pete. Sorry to make you repeat all that…. I must be a dense body, but I always manage to clear the neighbourhood around my orbit!

  • Pete Baker

    Glad to be able to clear up any confusion, Miss Fitz.

    I see no-one has commented on the local connection in the IAU General Assembly voting, Jocelyn Bell-Burnell.

    It’s only a slight connection but still…

  • DK

    So Pluto was all spin over substance. Or did Ceres and 2003UB313 not get good enough PR?

  • Pete Baker


    Ceres is an interesting case.

    It was originally considered to be a planet, for about 50 years, then reclassified as an asteroid, or minor planet, almost made the full planet league this time, but has been slightly promoted.. to dwarf planet status.

  • An Beirneach

    It is obvious that this is a plutocrat conspiracy by unreformable elements in the International Astronomical Union

  • inuit_goddess

    It’s the worst form of gerrymandering, they deliberately set the definition up to exclude Pluto. What have they got against her? She’s just a wee little spinning thing and all these bearded wonders are just ganging up on her!

    Save Pluto! Hasta la Victoria Siempre!

  • Pete Baker


    Jocelyn Bell-Burnell does not have a beard ;p