Pluto : My part in its downfall

January 10, 2007

OK. I confess. It was me. I killed Pluto. Well, it was me and about four hundred other random astronomers at the IAU General Assembly. As we sat there in the Grand Conference Hall, and slowly raised our pale yellow voting cards, Pluto’s fate was sealed.

I was reminded of that summer afternoon in Prague when I saw a recent news item about “plutoed” being the word of the year according to the American Dialect Society. Apparently to be pluto’ed means to be demoted in stature or value. The Pluto episode taught me two lessons; the first was about science and human culture; the second was about democracy.

But first, lets get one thing straight. Is Pluto’s change of status of scientific importance ? Nope. When Pluto stopped being a planet, did it fly out of its orbit ? Did its material composition suddenly change ? Did the known facts about the solar system alter ? Did theorists have to throw their pet models out the window ? Should we stop Pluto Express and bring it back ? Lift-off to PlutoNo, no, no, no and no. I find myself remembering the gag about how you tell the difference between a physicist and an astronomer. You show them both a scatterplot of random points. The physicist draws a curve through the points and claims that her model fits the data. The astronomer draws two vertical lines and labels the diagram Class I, Class II, Class III. (Where did I hear this joke ?)

Most of the two thousand astronomers at the meeting were not solar system types. Through the fortnight we were getting fed up with all this pointless stuff about Pluto, and worried that we would be looking foolish in the eyes of the world, debating how many angels fit on the head of a pin. By the time of the assembly on the last day, there were only 4-500 of us left, but again nearly all these were not planetary astronomers. Basically we looked at the resolutions and said right, does one of these look vaguely reasonable ? Yup, that one, ok right. Yes we agree. Next ? Can we do something serious now ?

Then something strange, magical, and twenty first century happened. The hall had wireless and many of us were on our laptops web browsing, checking email, etc as per normal. Within one minute of the vote, I heard somebody say “wow ! the news is on the BBC web site already !” To my left, Francoise Genova confirmed that the news had hit France too. I left the hall and spotted several colleagues on their mobiles to journalists. I got the subway back to my hotel, turned on the TV, and there was the story on CNN, complete with a grainy video of people voting with their yellow cards, that someone had taken inside the Hall on their mobile phone. A day later I was back in Edinburgh and my secretary was asking what Pluto had done to me and my daughter was frosting me for doing something so horrible.

I gradually realised this wasn’t just a big jokey thing. People actually cared. Furthermore, by and large the stories were fairly accurate. People were interested in the science – discovering lots of objects past Neptune, what this meant for the history of the solar system – but really it was a cultural thing. The planets are in movies, novels, school posters, TV quizzes, people’s dreams. Too often we take a patronising attitude to communicating science ; we know what is important, and try to explain it patiently to hoi polloi because it is good for them. But we are not priests holding sacred truth; we are technical experts. What matters and what does not is decided by human culture, owned by us all. Pluto belongs to the people.

Which brings me to Lesson B. The fateful vote on the last day was not the first Pluto vote. Some days earlier, a motion proposed by the Executive had been roundly rejected, partly because it was a daft idea, opening the floodgates to thousands of planets, and partly because it was felt to be foisted upon us by the Executive without adequate discussion. On the final day, Michael Rowan-Robinson, currently president of the RAS, made a beautiful speech. It had been necessary, he explained, to give the Executive a bloody nose; but now that open discussion had been had, and a reasonable proposition placed before us, the wise course of action was to close the issue. And so we did.

In the modern West, we are used to the idea that “democracy” means only picking a representative. The government makes all the decisions. At its root in fifth century Athens, it meant debate and decision by the Assembly of all citizens. (Not slaves of course…) Mostly, this ain’t workable. But every so often – the velvet revolution, the Pluto vote – the idea of mass democracy re-emerges. This is confusing for scientists. Truth cannot be decided by voting (whatever Paul Feyerabend says), but it cannot be decided by authority either. What is the right social organisation for science ?