Tyson and Sykes Duke Out the Great Planet Debate; Flatow Almost Flattened
Written by Nancy Atkinson
A debate today between astronomer Neil deGrasse Tyson and planetary scientist Mark Sykes, moderated by NPR's Ira Flatow, addressed the issue of Pluto's planetary status. There was lots of arm-waving and finger-pointing, endless interruptions, disagreements on details big and small, and battling one-liners. The two scientists sat at a table with the moderator between them and Flatow was often obscured by Tyson and Sykes getting in each other's faces in eye-to-eye confrontation. At one point, Flatow was hit by Tyson's ebullient arm motions. Yes, it was heated. But it was fun, too. It ended up being not so much a debate between the Pluto-huggers and the Pluto-haters as a disagreement over the lexicon of astronomy and planetary science and, primarily, the definition of a planet. Pluto's planetary status was definitely not decided here, and the debate concluded with an amicable agree-to-disagree concurrence that the scientific process is an ongoing, evolving practice. But it wasn't without fireworks.
At the start of the Great Planet Debate, Flatow laid down the ground rules, which included no throwing of perishable items, but that was about the only rule that didn't get disregarded. Tyson, director of the Hayden Planetarium in New York and host of Nova ScienceNow, and who is in the camp that Pluto is not a planet, began his opening statements with "It's simple. The word 'planet' has lost all scientific value." He went on, saying "planet" doesn't tell you much and you have to ask all sorts of questions such as is it big or small, rocky or gaseous, in the habitable zone or not, etc. "If you have to ask twenty questions after I say I've discovered a planet, the word has lost its utility." Tyson said "planet" had utility far back in time when there wasn't much else we knew about, but we know so much more now. "If we're going rely on one word and put them all in one pot, what are we doing as scientists and educators? The time has come to discard the useless words and invent a whole new system to respect the level of science we have achieved…We're in desperate need of a new lexicon to accommodate this knowledge," he said.
Sykes, director of the Planetary Science Institute, and who believes Pluto should be reinstated as a planet, began, "How we categorize things is part of the science process. It is natural for humans to group things together with common characteristics as a tool to better understand and how they work. This applies to biology and astronomy as well." He continued that we have discovered planets around other stars and continue to find Kuiper Belt objects that will need to be classified, so classifying objects is not a useless task. The IAU (International Astronomical Union) bit the bullet and decided on a classification, but unfortunately, Sykes said, what they came up with was not very useful.
That was the end of decorum, as Tyson interrupted with, "You wanted a definition. They gave you a definition and now you're complaining about it!"
"Absolutely," said Sykes, wanting to continue, but Tyson quickly chimed in, "And let me add…", where Sykes butted in with "You have to let me start before you add!"
Flatow looked around and said, "I think I'm in a danger zone here."
Thus began the debate.
Mark Sykes
Sykes said that any definition has to have a reason, or a purpose. According to the IAU's definition, planets have to orbit the sun, they have to be round, and they have to have cleared their orbits, among other things. There was immediate confusion with this definition, which Sykes said was a little "goofy." In order to be a planet, an object has be bigger the farther away it is from the sun, and it ignores the physical characteristics. He believes it's useful to group things together that are similar and then have subcategories. So, you have planets, under which are terrestrial, gas giants, ice planets, etc.
Tyson said that even for him, the IAU's definition falls short of taking the total amount of information to task. "If you only want to call round things planets, that puts Pluto in the same class as Jupiter. I happen to like round things. But what other lexicon might be available to group similar things together?"
"That's why god made subcategories," said Sykes. "It's good to have a good general starting point for classifying things."
Neil de Grasse Tyson
Tyson humorously pointed out this debate is big only in the US, which he attributed to Disney's creation of the lovable, dimwitted cartoon bloodhound named Pluto. School kids, grownups, op-ed writers all say Pluto is their favorite planet. "I am certain that the word 'plutocracy' is traceable to what Disney has done, so it's hard to extricate the sentiment we have for the planet from the dog."
Sykes said the IAU didn't expand our perspective on planets, but narrow it. "The planet count went down, and what was the justification of that? The proponents have never given a good explanation of what was motivating that perspective."
Tyson said numbers aren't important, but words and definitions are, and we definitely need new ones.
Both scientists gave good arguments for their cause, and since I'm decidedly on the fence with this issue, I found myself leaning towards one option or the other, as each one spoke. Sykes, who wants to see Pluto reinstated as a planet, wants to take what we have and make it better, while Tyson, who thinks Pluto is a comet, wants to start over with new and better words and definitions.
It was an entertaining and educational debate with two well-spoken and intelligent scientists who sometimes weren't very polite, however. (Sykes said, "When were' not fighting we get along fine.") The most important thing, they both agreed though, was that scientists are actually talking about this issue in the public eye and people are interested. But more importantly, the public is seeing the scientific process in action. They said this debate shouldn't be about making things easy, or worrying about "not confusing the public." Learning science shouldn't be rote memorization of lists of objects, but a discussion of how objects are similar and different. "My recommendation to school teachers," said Tyson "is to get the notion of counting things out of your system and comb the solar system for the richness of objects. Ask about different ways to combine the different objects in our solar system and have a discussion about their different properties."
The debate will be available online, and we'll post a link to it here when it is.
Sykes ended with his closing argument: "We both have issues with what happened with the IAU, its part of an ongoing presentation, but the important things is that the public gets to see the debate, and it's not a battle over what list and what numbers you have, but the debate of the issues. That's more important whether either of us have convinced you of one perspective. Science in this country is too much memorizing lists promulgated by those in authority. This is helping to expose the messy side of science. This debate is good and positive."
Tyson ended by saying how charmed he is at the level of public interest in this subject. "How many sciences get to have their issues debated in the op-ed pages and comics?" He said he was happy with the word "planet" until all the data started pouring in from our explorations. "There should be a way to celebrate a new way to think about things. There ought to be a way to capture that" he said.
Obviously, this is not the last word on the subject from either scientist, or either side of the debate.
But that's a good thing.
For more info on the Great Planet Debate.
August 17th, 2008 at 4:49 pm
Well, although it's true that many of the exoplanets discovered so far have quite eccentric orbits (and it's useful to stress out that they are *all* larger than the Earth), I don't think we have any data regarding inclination. Remember that it's not our ecliptic that matters there, but the local orbital plane. And, given what we know about the mechanism of planetary formation and the fact that the protoplanetary disks are *disks*, it's not likely that the variety in inclination will be comparable to the variety in eccentricity we are already seing.
Still, it's perfectly possible that we'll end up finding large planets in high-inclination orbits. Which in my vew means that is quite inadecuate as a limiting factor for what a planet is.
It's time people abandon once and for all the preconception that planets have to be in low-eccentricity orbits, all in the same plane, and spaced regularly. Bode's law is dead, as dead as Kepler's music of the spheres. The Universe is a messy place and does not obey our desire for order. Planets come in all sorts of configurations and sizes, and it's about time we learn to deal with that fact.
August 18th, 2008 at 8:22 pm
About this planets definition - thing … I very much appriciate so many comments on this matter. Not in, or with the purpose, of defining our "planets solar system" - but in order to define 'what is what' - out there.
I appriciate Sykes comment saying that "any definition has to have a reason, or a purpose".
I wouldn't mind if our solar system only contains 8 planets, allthough my emotions bases on my time of historical understanding react against this. I would submit to an eventually clear scientific explanation and purpose of another comprehension of - what and how our solar planet system is, and what belongs to this. But that's onfurtunately not the case with the IAU's definition.
I believe there are three components in our discussion of the planet definition:
1) The scientific … pure knowledge as we by now agree on, to be proved about matters and shapes.
2) The psycological … We want to define things for our own sake - the univers really don't care. The universe in itself doesn't need to be defined - it is what it is - rather chaotic … doing and finding its own possible ways and systems without any purpose defined be humans. .
3) The philosofical … Deals with not a single observation or some restrictive definitions of things, but comprehend a deeper understanding as to the why's and how's things relate and reacts to itself and the surroundings. Allthough philosofical viewpoints are depending on scientifis 'faktums' it goes byon the selective mediate faktums, and trying to define things in longer proposeable terms.
The different viewpoints are more or less inclined to 'either or' to these components.
Let me guess on what's going on psycological in the IAU's way of thinking.
As I beleive, like the rest of us, they have feelt a certain amount of content in the 'Nine planet solar system'. Now, with the latest discoveries - they feel rather unsetled about this 'nine planet solar system' … understandable - and what a disorder - our general understanding of our solar system rattles. Somehow Pluto have allways seems to be a bit different from the other planets, now believed to be a rocky icy planets - possibly a bit similar to asteroids. And now, so many more off these - what a mess - a disorder in our comprehention og what is our 'solar planets system'?. They beleive to have only two choices. Maintaining our present view of the 'nine planets solar system' or an ever changing definition of that … or, withholding the present, due to facts contravicting this.
Between these two unsettled evils - they seems to prefer to give rid of Pluto, in order to get a defininately and long lasting definition of what our solar planets system is. No more disorder.
If this is the case? It's understandable from a psycological point of view. But let us remember - the univers really don't care, (and I don't either). Why not settle on a more comprehensive and futuristic point of understanding? There are other solar systems, and much more to be defined - why not find a definition which is more basic and universal - including what other solar systems definitions of stars/solar planet systems are - and to be defined - and make our own solar systems definiton in accordance with this more universal way of thinking/understanding and definition of matters?
As mentioned before, I beleive the IAU untill now underestimate an importent observation of matters … the ability of the cosmis matters to create spherical shapes - the very first indication of nature to create order in chaos - in a certain sense the essentials for the evolution of organic life.
In astronomical terms physical astronomi explain the achiments of this sphrical shape as due to gravitational forces. I believe this is correct, but I also realise that untill now we don't really know what gravity is. We know quite exactly how it behave, but actually don't know what create gravitation.
I have my own theories, which I can not yet prove. But no matter what is the explanation, I beleive we all should have a deep respect and gratitude that spherical shapes can envolve in this universe, and agree to call this phenomens for planets - then we on a simple term know - what we a talking about. Subsequently we can make all kinds of subclasifications, as to the different kinds of planets. Why not be a bit humble - as to all what we don't know?
Have a nice sol.
Harry
August 20th, 2008 at 12:08 am
When is a dwarf planet not a planet? Why, when it's a DWARF planet, of course. When is a dwarf planet a planet? Why, when it's a dwarf PLANET, of course. Go figure! In any case, good terminology should be a prerequisite for good definitions.
October 9th, 2008 at 4:19 am
Pluto IS a planet.