Pluto, Little Pluto

The Pluto Files

Once upon a time in our solar system, couldn’t make do without 9. But Pluto’s not a planet now, so 8’ll do fine.”

-from the Barenaked Ladies song, 789

I’ll admit that I was with America in its indignant reaction to Pluto’s demotion to dwarf planet back in 2006. The decision, made official by a vote of the International Astronomical Union’s members, was preceded by a quietly bubbling controversy surrounding the redesign of the Hayden Planetarium in New York City’s American Museum of Natural History in 2000.

The museum’s then-new Scales of the Universe exhibit grouped Mercury, Venus, Earth, and Mars as terrestrial planets, and Jupiter, Saturn, Neptune, and Uranus as gas giant or Jovian planets. But, over the course of a year, astute visitors, many of them children, would count up the planets and come up with only 8, leading them to make the observation, “Did they forget about Pluto?”

In his surprisingly light and lively book, The Pluto Files: The Rise and Fall of America’s Favorite Planet, Neil DeGrasse Tyson, an astrophysicist and director of the Hayden Planetarium, recounts the science that left dwarf planet Pluto in a class, it would seem, by itself. By reviewing Pluto’s ups and downs, from its discovery back in 1930 to its entrenchment in pop culture, and, ultimately, to its central role in the first major cosmic recategorization dustup of the 21st century, Tyson explores the powerful forces exerted on space science by tradition, sentiment, enculturation, and even universally memorized solar system mnemonics.

What I love about this book is that it’s full of factoids (like these—By mass, Pluto is mostly rock, but by volume, it’s mostly ice; and, after the discovery of the planet qua asteroid Ceres back in 1801, the planetary count skyrocketed to 23, only to be knocked back down to 8 when all the asteroids in the belt between Mars and Jupiter were deleted from the planetary roster). It also weaves in fun tidbits (Like in 2006, the seven dwarves invited Pluto to join them, making the count of both dwarves and the planets an even 8; and, in the midst of the controversy, Stephen Colbert gave this shout-out to Pluto’s fellow Kuiper belt object 2003 UB313, which is now known as the dwarf planet Eris: “Hey 2003 UB313, if that is your real name, you’re not a planet you’re just a lazy comet. Your mama’s so ugly, she named you 2003 UB313!”).

For me, the thought-provoking part of the book came when it shed light on revolutions in science. When Copernicus proposed that the Earth revolved around the Sun, for example, he was changing a long-held paradigm. Art, literature, commercial branding, and even the religion of the time might have held on to the “Earth is the center” model, but that wasn’t going to change the fact that the paradigm was wrong. The same is true of Pluto. We can think what we will about its planethood (and grieve that “My Very Elegant Mother Just Sent Us Nothing” doesn’t have the ring of its former 9 word incarnation), but none of that changes the fact that Pluto is more like the other icy objects in the Kuiper belt that lies beyond Neptune than it is like its former planetary colleagues.

Tyson doesn’t come out and say this, but the way I look at it we’re Americans (those of us who live in America, at least), and if we can recast used cars as “pre-owned,” garbage men as “sanitation engineers,” and the artist currently known as “Prince” as the successor to the artist formerly known as “Prince,” then I’m sure that we can get the hang of this dwarf planet thing.

Just don’t ask me to call the Lehigh Engineers the “Brown and White.” That was just wrong.



  1. Lorraine said,

    May 8, 2009 at 10:26 am

    My class and I are studying the Solar System this term. Many of my students are convinced that someone was being mean to Pluto so one team is investigating how and why it’s been demoted!
    The students are looking forward to visiting our little local planetarium on excursion. It’s at the Uni campus at Mawson Lakes. I’m a little intrigued as we are doing a session in the animal centre on “How the Solar System affects animal behaviour”. (Wonder if will give me any insights to use in class?)

    • scheirmad said,

      May 9, 2009 at 10:44 am

      I wonder whether your students will come up with some of the points in the next comment, from Laurel. Read on…

  2. May 9, 2009 at 12:07 am

    Eight will NOT do fine, as the controversial demotion of Pluto in 2006 was simply wrong. The fact that four percent of the IAU, most of whom are not planetary scientists, voted on this demotion does not change reality. In fact, their vote was immediately opposed by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto. There is no need to change the paradigm of including Pluto as a planet because that paradigm is not wrong. Unlike most of its fellow Kuiper Belt Objects, Pluto is in a state known as hydrostatic equilibrium, meaning it is large enough for its own gravity to have pulled it into a round shape. This is a characteristic of planets and not of shapeless asteroids and Kuiper Belt Objects.

    The petition of astronomers who oppose the demotion can be found here:

    A conference held at the Johns Hopkins University Applied Physics Lab in August 2008 in response to the IAU decision, titled the Great Planet Debate, did a far better job in presenting both sides of this ongoing debate. Audio and video transcripts of the conference can be found here:

    The IAU definition makes no linguistic sense, as it states that dwarf planets are not planets at all. That’s like saying a grizzly bear is not a bear. Second, it defines objects solely by where they are while ignoring what they are. If Earth were placed in Pluto’s orbit, by the IAU definition, it would not be a planet. That is because the further away an object is from its parent star, the more difficulty it will have in clearing its orbit.

    A second reason the IAU definition makes no sense is that it defines objects solely by where they are while ignoring what they are. If Earth were in Pluto’s orbit, according to the IAU definition, it would not be a planet either. A definition that takes the same object and makes it a planet in one location and not a planet in another is essentially useless. These reasons are why many scientists and lay people are working behind the scenes to get the demotion overturned.

    The well-justified rejection of Pluto’s demotion was not limited just to the US and not confined to 2006. Both astronomers and lay people are working today to overturn the demotion, while others are ignoring it entirely.

    For more on why Pluto is a planet, read Dr. David Weintraub’s excellent book “Is Pluto A Planet” and feel free to visit my Pluto blog at . I plan to write my own book about Pluto, which should be out in a few years. I hope you will look for it and read it too. Everyone deserves to know there are two sides to this ongoing debate.

  3. scheirmad said,

    May 9, 2009 at 10:50 am

    Hi Laurel. Thanks for the other side of the story!

    I hope that it’s clear from my piece that it was a review of the book, with a presentation of my own conclusions (and a splash of humor), rather than a definitive answer to all things Pluto. I am by no means an expert, but I found many of DeGrasse’s arguments persuasive. He, as I’m sure you know, is not alone on his side of the debate either.

    It certainly is exciting to see such lively interaction among scientists about something that is at the same time very concrete and awfully abstract. I have to say that regardless of where science eventually lands on this subject, my knowledge base has benefited from the debate.

    Good luck with your book! Please drop me a line when it comes out!

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