How I Killed Pluto and Why It Had It Coming - Mike Brown [99]
Great, I thought. Another guest would help me to stay focused and coherent.
When we went live on air, I suddenly realized that the astronomer was none other than the member of the once-secret planet-definition committee, live from Prague! It had been an even longer day for him than it had been for me.
He seemed tired, and he definitely didn’t seem happy. He talked about how he thought the vote had done a disservice to astronomy. I said I thought astronomy had done a great service to the world.
He said that he was sad that no one would ever again be able to discover a new solar system planet under the current definition.
“You know,” I said, over the radio to him half a world away, “when you tell me that no one will ever discover a planet again, I just take that as a challenge.”
Over the course of the radio show, we both answered questions from callers. It was becoming clear that the idea that Pluto was no longer a planet was not going to be an easy sell.
Throughout the hour, the host collected suggestions for a new mnemonic for remembering the order of the planets. Some gave a slight modification of the previous standard—My Very Educated Mother Just Served Us Nine Pizzas—by turning “Nine Pizzas” into “Nachos” or into “Nothing,” which was a bit funnier. But the best mnemonic, and the one that I still tell people to use to this day, sent in by an anonymous listener, sums up the feelings that would envelop much of the world over the next days, weeks, and months:
Mean Very Evil Men Just Shortened Up Nature.
Chapter Thirteen
DISCORD AND STRIFE
Keeping Pluto dead has taken a lot of work.
In the days, months, and years since the decision was made, I’ve been accosted on the street, cornered on airplanes, harangued by e-mail, with everyone wanting to know: Why did poor Pluto have to get the boot? What did Pluto ever do to you?
It is at these moments that I am most happy that astronomers ignored my initial advice to simply keep Pluto and add Xena and forget about a scientific definition. I am thrilled that astronomers instead chose to put a scientific foundation behind what most people think they mean when they say the word planet. They don’t mean “everything the size of Pluto and larger,” and they certainly don’t mean “everything round.” Instead, when people say “planet,” they mean, I believe, “one of a small number of large important things in our solar system.”
My job is just to explain the solar system as it actually is. People, I think, will then realize themselves that Pluto is not one of these large important things in our solar system.
Here is what I say to people:
Many astronomers, tired of the endless debates before and after the demotion of Pluto, will tell you that, in the end, none of this matters. Whether Pluto is a planet or not is simply a question of semantics. Definitions like this are unimportant, they will say. I, however, will tell you the opposite. The debate about whether or not Pluto is a planet is critical to our understanding of the solar system. It is not semantics. It is fundamental classification.
Classification is one of the first processes in understanding something scientifically. Whenever scientists are confronted with a new set of phenomena, they will inevitably, even subconsciously, begin to classify. As more and more things are discovered, the classifications will then be modified or revised or even discarded to better fit what is being observed and what they are trying to understand. Classification is the way that we take the infinite variability of the natural world and break it down into smaller chunks that we can ultimately understand.
So how should we classify the solar system? It’s hard, because we are sitting in the middle of it and have known planets our whole lives. But let’s try to do it from the perspective of someone who has never seen a planet before. Imagine that you are an alien who has lived your whole life on a spaceship traveling from a distant star to the sun. You don’t know that planets exist.