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David H. Levy's Evening Stars: Pluto's second chance

October 2010: The planetary scientists of tomorrow choose a definition of planet for today.
David Levy
In 2006, the International Astronomical Union (IAU) voted to demote Pluto to dwarf planet status. Four years later, Pluto reclaimed its status as the ninth planet after a second vote — at least, it did so in the eyes of the unofficial voters.

Although the new vote did not involve members of the professional astronomical community, I say it is just as valid. In my discussions with these second voters about Pluto, I emphasized that my opinion to keep it a major planet had nothing to do with science, despite the scientific reasons that it orbits the Sun and its gravity molded the object into a sphere. In fact, 4 years ago an IAU-appointed committee — headed by the great Harvard astronomer Owen Gingerich and including such notables as Massachusetts Institute of Technology astronomer Rick Binzel and science writer Dava Sobel — cited these same reasons. They unanimously recommended that Pluto, its moon Charon, the asteroid Ceres, and the Kuiper Belt object Eris all be considered major planets.

I agree with the committee and believe they did a superb job. But the full IAU membership ignored their work and voted to demote Pluto, defining "planet" as an object in orbit around the Sun that gravity has transformed into a sphere that has also cleared out its orbit of smaller bodies.

My opinion on the subject stems from my longtime close friendship with Pluto discoverer Clyde Tombaugh (1906-1997). He certainly saw this coming; in his final years, he fretted about the IAU eventually robbing him of his signature discovery.

Some elected officials have already listened to the protests of Plutophiles like me and made changes. The legislatures of Illinois and New Mexico, where Tombaugh was born and where he lived the last 50 years of his life, passed clearly worded resolutions insisting that when elusive Pluto is visible in the skies over these states, it is legally a major planet. Moreover, if you plan to build a home in New Mexico's Pluto Park area, at Rancho Hidalgo, where Tombaugh's 16-inch telescope still points skyward, you must sign a contract supporting Pluto's status as a major planet. I applaud these decisions.
October 2010 Roslyn's campus
Roslyn's campus is not only home to the author's grade school classrooms, but it was also where the recent Pluto vote took place, unofficially reinstating it as a major planet.
David H. Levy
After all, what of the future, when hundreds or thousands of Pluto-sized worlds might turn out to hide in the Kuiper Belt? Are they all demoted to dwarf planet status as well? If you define "planet" simply by using only the characteristics of the world itself (and not the characteristics of its orbit), then the IAU is just plain wrong.

About 4 years after their vote, I thought it was high time to bring it up again and chose the most fitting place I could think of — an elementary school named Roslyn in Westmount, Quebec. The school is special to me because I spent 5 years there beginning in 1956. It is the forum that saw my first lecture in the spring of 1960. Roslyn has something else going for it right now: Roger Pelland, an experienced and truly exceptional science teacher. Because the definition astronomers select today will affect the scientists of tomorrow, why not let children have a role in the decision? After all, it is they who will have to live with the eventual definition of "planet."

The third graders voted unanimously to reinstate Pluto's planetary status, and the fifth graders voted for it 56 to 6, for a total vote of 100 to 6. The results are consistent with those already taken among millions of school children across the world.

I suspect that like many good words, "planet" will one day have several definitions, from which anyone can choose the one most palatable. In the meantime, I believe the children of the world, represented by some very clever young minds from Canada, have spoken clearly. They do not want the politics of a distant organization to dictate rules about the natural world they will enjoy and of which they will someday be in charge. Good work, Roslyn, and vive Pluto!
Read More of David H. Levy's Evening Stars
September 2010: Dr. David Levy-Shakespeare
See an archive of David H. Levy's Evening Stars
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