How I Killed Pluto and Why It Had It Coming - Mike Brown [79]
I went back and checked the e-mails recently. It is true that Ortiz never publicly denied having used the data, even in the early days. He just never answered the question. All of the denial came from his German friend, who, I still believe, had been equally duped. I wonder if he secretly suspected that something was amiss or if he was simply as trusting and naïve as I used to be.
Chapter Eleven
PLANET OR NOT
On that Friday morning in late July, I made the instant decision to announce to the media that Xena was the tenth planet. I had been swayed in part by Diane’s arguments and in part by the urgings of the media relations person to whom I spoke that morning. But even though I was a bit blindsided that morning, all spring I had been trying hard to understand how we should define the word planet.
I asked an old college friend with a Ph.D. in philosophy: What does a word mean when you say it?
“Words mean what people think they mean” was his smoothly philosophical reply. “So when you say ‘planet’ it means what you are thinking when you say it.”
I probably should have known better than to ask him. I remembered that in college he had told me that he woke up every morning surprised that reality was still reality.
Still, maybe there was something to it. Maybe words do just mean what we think they mean.
Perhaps it is wrong for astronomers to attempt to redefine a word when people already know what it means when they say it. Perhaps the job of astronomers is, instead, to discover the definition of the word planet as people use it. After all, the word planet has been around much longer than, well, our understanding of planets.
So what do people mean when they say the word planet? That spring, well before anyone knew that the world was about to be handed a tenth planet, I started asking everyone I saw. The answers were diverse and, more often than not, scientifically misguided: large rocky bodies in the solar system (well, no, there are gas giants), things with moons (not Mercury or Venus!), things that are big enough to see with your eye (Uranus, Neptune, and Pluto are out), things that pull the earth around in its orbit (that’s just the sun). But when I then asked people to name the planets, everyone had exactly the same answer, starting with Mercury and ending with Pluto. People who felt themselves quite up to date and informed would then explain that maybe Pluto shouldn’t be called a planet, but they certainly knew that it currently was one.
So, again, I ask: What do people mean when they say the word planet? They mean a slew of unscientific clutter. And then they mean nine specific objects in the solar system.
I always pressed people further: How would you know if something new was a planet? The answer was always the same: If it was as big as the other planets. Or, as I interpreted it, according to my unscientific springtime poll, everything the size of Pluto and larger that orbits around the sun is a planet.
Isn’t that the real definition, then? Shouldn’t astronomers leave the word alone if it already has a meaning?
I remained torn. If Pluto was a planet, why were the many things just a little smaller than Pluto not considered planets? It made no scientific sense at all. Why draw such an arbitrary line right around the size of Pluto? Isn’t the job of scientists to guide the public’s understanding of nature rather than acquiesce to unscientific views?
In addition to everything else happening that spring, while Xena and Santa and Easterbunny were just being found and studied, and Lilah—still known as Petunia—was growing and beginning to kick inside Diane’s stomach, I was teaching introductory geology at Caltech for the first time. I’m not a geologist. I’ve never taken a single class in geology. If you gave me a handful of different types