How I Killed Pluto and Why It Had It Coming - Mike Brown [89]
I love the Library Fair and—out of sheer exuberance—always buy used books that I would not otherwise even glance at. And then I sit on Diane’s mother’s porch on a midsummer twilight lasting until well past ten o’clock and read.
But during this very first family vacation with Lilah, I had no opportunity to relax and read on the porch. My vacation coincided with the once-every-three-years meeting of the International Astronomical Union, this year in Prague. And at this meeting, for the first time in history, they were finally going to vote on the definition of the word planet.
Why wasn’t I there? Why was I vacationing half a world away from where the astronomical action was?
It’s a good question.
There are four answers to that question. First, I love the Library Fair. Second, it was our first family vacation. Third, no one—not even the astronomers who found themselves in Prague—had been warned that the vote about planets was imminent. I admit, had I known ahead of time that this vote was going to take place, I might have felt obligated to be there rather than to abscond to a small island in the Pacific Northwest. Luckily, I didn’t know. Fourth, and probably most important, I am not a member of the International Astronomical Union. I would have been ineligible to vote. I’m embarrassed to admit that I can’t get myself to fill out the paperwork to join. It’s all because of Question 12 on the form. After the form asks for your academic qualifications and awards, both of which I can handle, it then quizzes you about your miscellaneous special distinctions. And then I stop. Well, I think, I’m no William Herschel (the discoverer of Uranus, which is indisputably a planet). I’m no Adams or Leverrier or even Johann Galle. (Adams and Leverrier predicted the existence of Neptune, and Galle confirmed it.) Really, I wonder, do I have any special distinctions? And each time I get to that spot in the application, I have to stop and put down my pen. There was no reason to bother going to the International Astronomical Union meeting in Prague because I would not have been let in the doors.
• • •
I was sitting in Diane’s mother’s house on Orcas, watching the sailboats navigating Westsound out the window, when an e-mail arrived from the other side of the world telling me the details of what, precisely, the IAU was going to vote on. I read it to Diane in my excitement.
“Diane, Diane, it says right here that the planets are to include the big eight, of course, and then also Pluto and 2003 UB313—that’s Xena—and wait a second, there are a few more.” I was confused. Xena and Pluto were nine and ten. But there was also to be Ceres—the asteroid discovered in 1801 that was declared not-a-planet sometime around 1850. And in a surprise that I had never anticipated, Charon, the moon of Pluto, which was about half the size of Pluto, was to be number twelve. Twelve planets. Not eight, nine, or ten, or even two hundred, which I would have understood. And Charon? The e-mail didn’t make any sense. I didn’t recall any discussion in which naming Pluto’s moon a planet had ever come up before. What was the committee thinking? Who in their right mind would declare Charon a planet?
I reread the e-mail carefully. The committee, which had met in secret, was adhering to the notion that “all round things are planets,” which I had thought was a bad idea to begin with but which I at least understood and could support as a scientifically rational and consistent