In 2006, in a musty old hall in Prague, Czech Republic, a group of astronomers belonging to the International Astronomical Union voted on the official definition of “planet.” In one fell swoop, the former planet known as Pluto was demoted, sending millions of us who learned about the “nine planets” into paroxysms of confusion.
“This is how science works,” says Dr. Horatio Allan Tibbets, an astronomer at the Cloudy Mountain National Observatory in Utah. “Our knowledge evolves, and we have to adapt the imperfect language that humans use to communicate with. The science hasn’t changed, Nature hasn’t changed, but how we understand Nature is changing. Our old ideas may have been perfectly good for explaining what we knew about the Cosmos; but as we see new things, we have to have new ideas that encompass the old ideas and explain the new ideas at the same time. It’s a tough tightrope to walk.”
The “Pluto debate” is one example of the evolution of scientific understanding, Tibbets says. “We made this big decision to change our taxonomy, demoting Pluto from the lineup of planets. But now, we’re learning some new things and it seems we should revisit this question again.”
Dr. Theo Partido of the Department of Physics and Astronomy at Greater Oklahoma Polytechnic University is a proponent of the Pluto demotion and not changing the current classification. “The simple fact of the matter is that Pluto is different than the other planets. It’s not like Earth; it’s not like Jupiter. It’s been put in its proper place and it should be kept there.”
Tibbets is part of a growing number of voices in the scientific community who disagree with this. Armed with new facts and new observational data, they are attempting to open a new dialogue that will once again change our notion of what it means to be a planet. “The fundamental issue is that we don’t know enough about the Cosmos,” said Tibbets. “This definition of ‘planet’ has been made by looking at only one solar system — ours! We don’t know enough about what other systems might be like, and that can lead to problems.”
By the current definition, a planet is only a planet if it has cleared its orbit of other bodies, like dust and rocks and asteroids. That is a serious flaw in the minds of many astronomers. “Imagine a system that has a planet like Jupiter in an orbit like Pluto’s,” said Tibbets. “In a scenario like this, Jupiter could not have cleared its orbit in the age of the solar system! It would not be considered a planet by the current definition, which is crazy! There are very few people who would argue there are cases where a world like Jupiter should not be considered a planet.”
Astronomers gathered this week at Creeping Ivy State University for a contentious meeting intended to find common ground between the two sides of this debate. While there has been insistence from both sides that they are here to have a discussion, the debate has already become heated and contentious. The rhetoric is vehement and the tension is palpable.
“The Plutoers are out of touch,” claims Partido. “The sooner they accept that they are wrong, the sooner we can move on.”
Tibbets does not mince words about this philosophical battle. “They’re ideologues, and don’t behave rationally. They call me a ‘Plutoer,’ like we’re still juveniles. Should I turn around and call them ‘dwarfers?’ No. Someone has to be a grown up; I’m here to talk about science.” Tibbets and a growing number of colleagues have been arguing to revisit the definition of planet in light of new information that is emerging from exoplanet studies, as well as tantalizing new data from our own solar system. “We can’t ignore that; that’s not how science works.”
“What we’d really like to see is a dialing down of the rhetoric and less clinging to ideology for the sake of ideology,” said Tibbets. “But that message doesn’t seem to be getting through.”
That much is evident when talking to people on the other side of the debate. “The Plutoers seem to think there is something to argue about here, but there isn’t,” insists Partido. “We’re right, and they’re wrong. Plain and simple. It’s water under the bridge, and they should get over it.”
NOTE: I’ve been writing long essays for this writescience experiment; I wanted to see what it would be like to be confined to a smaller space. This is about 25-30 column inches in a newspaper, based on word count. More than would normally be dedicated to a science story?