Saturday, June 13, 2009

The Pluto Files (Neil deGrasse Tyson)

The day after the International Astronomical Union voted to demote Pluto's status to a "dwarf planet," my friend and coworker Jenn printed out "I Heart Pluto" stickers for many in our office to wear in defiance. What? You didn't do this at your work on that day? Hmmm, then maybe you don't work in science. We felt compelled to stand up for Pluto, the underdog of the nine planets, probably because that's all we remember about the Solar System in elementary school science. How can you forget Pluto? It's the furthest away and the smallest. And it has the same name as Mickey Mouse's dog.

Neil deGrasse Tyson knows Pluto all too well for an astrophysicist whose specialty is not planetary bodies. As director of the Hayden Planetarium, in 2000 he was involved in the planning of the American Museum of Natural History's new Rose Center for Earth and Space. After much discussion about Pluto, they decided to side-step the issue by not talking about the nine planets as a whole and instead grouped items with other like items. The gas giants together, the terrestrial planets together, and then Pluto together with members of the Kuiper belt (in another area of the center).

Now, I can see how as scientists this grouping like-with-like made perfect sense to them, and how they could believe that this would resolve the issue, no problem, with no questions. But soon after opening day, although the media was not discussing it yet, some of their smallest critics saw right away that Pluto was missing from their Scales of the Universe display. All the other planets were there. Where was Pluto?

The Pluto Files: The Rise and Fall of America's Favorite Planet discusses the history of Pluto, the media storm around Pluto that began with the Rose Center's new design, and deGrasse Tyson's own personal history with Pluto (including just a few examples of the many, many letters he received some school children, along with letters and emails from working scientists and the general public). The book is engaging, written for a general audience, and brings up lots of great points: 1) We probably wouldn't have had this kind of public reaction to Pluto's reclassification if Pluto hadn't been discovered by an American, 2) There actually isn't an exact definition for what makes a planet a planet, and 3) Pluto does not care what we call it. It just goes on being Pluto.

The letters and emails contained in the book are great, and I want to highlight a couple here. Here's an email, accusing deGrasse Tyson of cultural insensitivity:

Would you say a small child or midget wasn't a person? Of course you wouldn't, although they are a different versions of the normal standard that is set as what a person would like, but they are still classified as people. By saying that Pluto is not a planet, is like saying a midget or a small child is not a person.
I'll end with a letter from Madeline Trost, an example of what deGrasse Tyson calls the "angry-kid genre." "After addressing the envelope to me personally, she bluntly addresses her letter 'Dear Scientest,' and she can't contain her flurry of assaults on my integrity, ending with an appeal to accommodate a shortcoming of her own":
Dear Scientest,
What do you call Pluto if its not a planet anymore? If you make it a planet agian all the science books will be right. Do poeple live on Pluto? If there are poeple who live there they won't exists. Why can't Pluto be a planet? If it's small doesn't meant that it doen't have to be a planet anymore. Some poeple like Pluto. If it doen't exist then they don't have a favorite planet. Please write back, but not in cursive because I can't read in cursive.


Laurel Kornfeld said...

Your initial instincts were right. There are strong scientific reasons for keeping Pluto classified as a planet. It is important to note that Tyson has distanced himself from the controversial 2006 IAU decision, which he himself admits is flawed. At this point, he even admits that the debate is not over, that it might be too early in the study of planetary scientists for anyone to be defining what a planet is in the first place. This was pretty much his message at the Isaac Asimov Memorial Debate, which he moderated at the American Museum of Natural History on March 10, 2009.

Significantly, only four percent of the IAU voted on Pluto's demotion, and most are not planetary scientists. Their decision was immediately rejected by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA's New Horizons mission to Pluto.

Stern and like-minded scientists favor a broader planet definition that includes any non-self-luminous spheroidal body in orbit around a star. The spherical part is important because objects become spherical when they attain a state known as hydrostatic equilibrium, meaning they are large enough for their own gravity to pull them into a round shape. This is a characteristic of planets and not of shapeless asteroids and Kuiper Belt Objects. Pluto meets this criterion and is therefore a planet, as are Haumea, Makemake and Eris in the Kuiper Belt and Ceres in the asteroid belt. This characteristic differentiates these bodies from the many others in those belts.

This debate is far from over. For another perspective, anyone interested in this topic should read "Is Pluto A Planet" by Dr. David Weintraub. Also, please visit my Pluto blog, which discusses the scientific reasons for Pluto maintaining its planet status and chronicles worldwide efforts to overturn the demotion, at

Alan Boyle is writing a book "The Case for Pluto," which will be out in October 2009, and I also plan on writing a book about Pluto, which will be out sometime in the next few years. Please make sure to consider both sides before taking a stand on this issue.

Unknown said...

If you ask me, and I realize nobody actually did ask me, demoting Pluto could be pretty dangerous. After all Pluto was in charge of Hades. I don't think we should mess with him by dissing his planet. All hell could break loose, assuming it hasn't frozen over since Pluto is so far from the sun.

If Pluto isn't a planet any longer does that mean we have to rename Plutonium?