The Great Planet Debate - August 14, 2008
It just won't end. Two years after the International Astronomical Union demoted Pluto from a planet to a dwarf, the bickering goes on.
I'm here at the “Great Planet Debate”, an event put on by the John Hopkins University's Applied Physics Laboratory in Laurel, Maryland, where several hundred scientists, teachers and members of the public have shown up to watch two scientists duke it out over definitions. The organizers say a Internet video stream of the debate will be posted here soon.
On one side, they've got Mark Sykes, director of the Planetary Science Institute in Tucson, Arizona, a Pluto proponent full of good-natured bluster. And on the other is Neil deGrasse Tyson, the hyperarticulate director of the Hayden Planetarium in New York City, who famously pushed Pluto out of its customary box as the ninth planet in his museum's exhibits. It was supposed to be a debate about planetary definitions -- but it quickly became all about that attention-seeking Pluto. The two clearly were having fun as they milked it for all it was worth.
“The word 'planet' has lost all scientific value,” says Tyson. “We're in desperate need of a new lexicon to accommodate our new knowledge.”
Tysons point is that subcategories and new terms should be developed as scientists discover new things -- and that strict categories only limit thinking. William Herschel, the discoverer of Uranus, thought he had found a comet. The first asteroids were called planets until it was realized that a huge population of objects sat between Mars and Jupiter. Now, Tyson argues, Kuiper belt object is a good new term for things like Pluto -- or dwarf planet.
Sykes is in favor of a more inclusive definition -- based on “roundness” -- that would include as planets big asteroids such as Ceres. His main problem of the IAU decision was the vagueness of a secondary part of the definition -- that a planet must be able to “clear” its neighborhood of other bodies. Sykes says that part of the reason for the IAU decision was a fear that, under a more inclusive rule, the solar system would eventually contain hundreds of planets. “My God, we can't have more than 10 planets,” he said earlier in the day, holding up his hands in mock horror. “We're out of fingers!”
But really, this whole event -- three days of presentations, posters and panel discussions -- has less to do with science and more to do with a debate about how science is taught. (The event also probably had a little to do with maintaining status for NASA's New Horizons mission to Pluto. And maybe a little to do with making money -- think of all the books, T-shirts and bumper stickers that this ongoing debate has spawned and sustained.)
Several generations of people grew up with nine planets, memorizing them in order. Tyson said he got emails that, in the wake of the Pluto demotion, would say: “My Very Energetic Mother Just Served Us Nine Pizzas. 'I just learned this mnemonic. Now what am I going to do?'”
Sara Seager, an exoplanet astronomer at the Massachusetts Institute of Technology, saw firsthand how the issue still resonates with the general public. On the shuttle ride from her hotel to APL this morning, her driver asked if she was going to the Pluto debate. She said yes. “And he looked at us very sadly and said, 'Please, please bring Pluto back.'”
Comments
I am a third grade teacher who teaches science. Please correct me if I am not understanding your article. Pluto as has been said keeps with the first two criteria for planethood-roundness-orbiting the sun. With the third criteria from what I understand of your article, Pluto and Charon share being dominate in their space. It therefore follows that their label should be double or binary planets. To simplify it for education, they should both be termed as planets.
I don't think that entry within Neptunes orbit should be taken into account since it happens only for a very small percentage of the total orbit. Pluto is a planet most of the time and not for a very small percentage. With the length of Pluto's orbit it must be inconsequential. So I would summarize that Pluto should be renamed as a planet.
Posted by: Kathy Wilmouth | August 15, 2008 02:18 AM
And it shouldn't end. We are continually discovering new data about Pluto, the Kuiper Belt, Ceres, Vesta, exoplanets, etc., all of which must go into informing our concept of what makes something a planet. I cannot understand this need to artificially end what is clearly an open discussion, largely because we just don't have sufficient data yet about some of these bodies to draw firm conclusions. What the IAU did was horrible--a linguistically nonsensical definition brought about through a highly flawed process that did not even adhere to the recommendations of its own committee. Should we just leave things in this mess because "the IAU has spoken" (well, four percent of them, anyway). What about the fact that most planetary scientists, those whose expertise and research specifically deals with planets, are not IAU members? Shouldn't these be the people making such a decision if it is made at all? There is a very real dichotomy between two strains of thought--dynamicists, who look at where objects are, and planetary scientists, who look at what they are. In an age where new knowledge is constantly pouring in, of course such definitions will be in flux. As for education, what is wrong with teaching that there are two schools of thought and both are equally valid? What is wrong with discussing something that excites people about astronomy?
What if we had decided to "cut off debate" and end discussion of what a planet is after the discoveries of Uranus and Neptune or after the 17th century revolution in which we realized the sun is the center of the solar system? How would we incorporate new information? What's wrong with the debate being ongoing???
Posted by: Laurel Kornfeld | August 17, 2008 05:31 AM
From what I understood of one report I read of the original IAU debate, a good proportion of attendees actually left before the vote deciding Pluto's fate was cast. Is this true?
Posted by: N | August 17, 2008 09:23 AM
And it shouldn't end. We are continually discovering new data about Pluto, the Kuiper Belt, Ceres, Vesta, exoplanets, etc., all of which must go into informing our concept of what makes something a planet. I cannot understand this need to artificially end what is clearly an open discussion, largely because we just don't have sufficient data yet about some of these bodies to draw firm conclusions. What the IAU did was horrible--a linguistically nonsensical definition brought about through a highly flawed process that did not even adhere to the recommendations of its own committee. Should we just leave things in this mess because "the IAU has spoken" (well, four percent of them, anyway). What about the fact that most planetary scientists, those whose expertise and research specifically deals with planets, are not IAU members? Shouldn't these be the people making such a decision if it is made at all? There is a very real dichotomy between two strains of thought--dynamicists, who look at where objects are, and planetary scientists, who look at what they are. In an age where new knowledge is constantly pouring in, of course such definitions will be in flux. As for education, what is wrong with teaching that there are two schools of thought and both are equally valid? What is wrong with discussing something that excites people about astronomy?
What if we had decided to "cut off debate" and end discussion of what a planet is after the discoveries of Uranus and Neptune or after the 17th century revolution in which we realized the sun is the center of the solar system? How would we incorporate new information? What's wrong with the debate being ongoing???
Posted by: Laurel Kornfeld | August 18, 2008 06:15 AM
Well I went to this debate this August and one thing stands out. Scientist are looking like fools in the eyes of the public.
Posted by: Gil. Knight | November 15, 2008 01:04 AM