More laughs.

"Wait!" I said, quickly turning the volume down. "This comment is really important. This part is insidious. This is deliberate! 5B, which is an amendment to 5A, is voted on after after 5A. 5A, which says Pluto is not a planet, will have general support, and then 5B will get snuck in to subvert the intentions of 5A. And no one seems to care." 5A. 5A, which says Pluto is not a planet, will have general support, and then 5B will get snuck in to subvert the intentions of 5A. And no one seems to care."

But no one other than me seemed to grasp the enormity of the conspiracy at hand. Sure, perhaps I was a bit on the exhausted side at this point and inclined to believe that the secret committee had also conspired to a.s.sa.s.sinate Abraham Lincoln, Archduke Ferdinand, and Julius Caesar, but just because I was being paranoid didn't mean I was wrong.

I turned the volume back up, and we were back to punctuation: The inverted commas look right when you see them, but you don't speak speak them. Could you not think of a new word which doesn't exist in the dictionary so that it doesn't have any baggage, and instead of calling it "dwarf planet," use some word, since it's an entirely new thing.... What you need is a new word rather than combination of old words; but a planet is a planet and so is a dwarf planet from a schoolmaster point of view. them. Could you not think of a new word which doesn't exist in the dictionary so that it doesn't have any baggage, and instead of calling it "dwarf planet," use some word, since it's an entirely new thing.... What you need is a new word rather than combination of old words; but a planet is a planet and so is a dwarf planet from a schoolmaster point of view.

I was feeling punchy and kept interjecting. "Yeah, he is right," I muttered. "'Dwarf planet' is a dumb phrase. For years we've called things like Pluto and Xena 'planetoids'-planetlike. That was a perfectly good word yesterday. But they're trying to be sneaky, they are. 'Dwarf planet' is dumb, but they need it so Pluto can become a planet with 5B."

The press at this point began to think that I was perhaps as crazy as all of the astronomers arguing over punctuation in Prague.

A question from the astronomical floor: "How does Charon fit?"

Right. At this minute there is confusion about Charon. If we pa.s.s 5A, Charon is not a planet. Right now I think there is confusion.

Someone else interjected: "It's a satellite! As long as it remains a satellite, it's out with this resolution."

Comment: "A point of clarification for me: Is a dwarf planet considered a planet?"

"That is Resolution 5B."

"In 5A a dwarf planet is not a planet?"

"Right."

In perhaps my favorite exchange of the very early morning, the question "Do I understand correctly that we are not anymore ent.i.tled to use the word 'planet' for planets around other stars?" elicited the response: "Are you referring to floaters, sir, or are you talking about extrasolar planets?"

Floaters? All I could think of were those little spots that you can sometimes see floating in your eye. I never heard the answer because I was at this point just shaking and shaking my head wondering how much longer this could possibly go on.

From a pedant: "Last Friday you mentioned we are not voting on the footnotes, but now you are referring to the footnotes. So are we voting on the footnotes or not?"

Response: "We were at one point trying to say that the footnotes are not part of the resolution. I think that position is not tenable; it is a stupid position. Therefore the footnotes are now part of the resolution."

Out of nowhere: "There is so much left in the resolution to common sense that I would propose to drop the entire resolution and leave Footnote One."

That was just about the best comment of the morning. The astronomer was right: The resolution that came up with a definition was so poorly written and vague that it would have been clearer to simply say what Footnote 1 said: The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Ura.n.u.s, and Neptune. Everything else was just an attempt to explain why-and a poor attempt at that.

The commenting went on for another hour before, mercifully, someone called for a vote. Those in favor of Resolution 5A, which would create eight planets and an unspecified number of dwarf planets, were asked to hold a yellow voting card in the air. The room was filled with the color of the sun. There was no need to count. Resolution 5A pa.s.sed with overwhelming support. Pluto was, correctly, no longer to be cla.s.sified with the other eight planets. It was a moment that I never thought I would see in my lifetime.

The press in Pasadena were aghast and astounded and excited. They were ready to hit the "send" b.u.t.ton to upload their stories.

"No no no, wait!" I told them. There was still Resolution 5B! This was where the conspiracy would happen! This was where the secret committee would subvert the will of the astronomical community! "Wait and watch!" I told them.

We watched. And then the most amazing thing happened. In the still-too-early fog of a not-enough-coffee morning in Pasadena, with the press watching astronomers half a world away, awaiting the secret sign to the pro-Pluto brotherhood to emerge to protect the G.o.d of the dead, I saw, instead, the moderator of the meeting stand up and make a few simple statements that put everything in precisely the right place. Where were the conspirators? Where were the daggers? Maybe I was in need of sleep.

Here is what she said: 5B involves inserting one word. Surely not a serious matter. However. For the benefit of non-astronomers present [but, really, isn't she doing this for the astronomers?], I want to do a bit of teaching, which demonstrates that resolutions are non-linear, and small changes have big effects. Excuse me while I dive under the table. [She pulls out a large beach ball, to represent planets, and a stuffed dog-Pluto!-to represent, well, Pluto.]At the moment, right now, having pa.s.sed resolution 5A, we have planets, the eight that are named [points to beach ball], we have dwarf planets [points to stuffed Pluto], and we have small astronomical bodies that are non-spherical. If we reject everything else this afternoon that is what will stand. If, however, we add the word "cla.s.sical" to this group [beach ball], then we have adjective planets [beach ball], different adjective planets [stuffed dog], and it could be argued that what we are doing is creating an umbrella category called planets under which the cla.s.sical planets and the dwarf planets fit. And if we do this then that [pulls out umbrella, puts beach ball and stuffed Pluto under it; audience erupts into applause] pertains.

"Who is is that?" someone in the press asked me. that?" someone in the press asked me.

The speaker was Jocelyn Bell, who was widely considered to have deserved a n.o.bel Prize in 1974 for her discovery of pulsars. I didn't need to speak; I just smiled. No conspiracy was going to happen on her watch. Although I wasn't sure what the outcome would be, astronomers were going to decide based on knowing exactly what they were voting for.

Only two comments were allowed. The first, in favor of the pro-Pluto resolution, was from the member of the once-secret committee who had called and told me that the committee's original definition, now dead, had been a.s.sured of pa.s.sing. Wearing a tie with planets on it, standing in front of the auditorium, he looked tense, angry, and maybe a little sad. He made his case: Using the words "cla.s.sical planets" is a compromise which allows more than one kind of planet in the universe. Yet advocates of the [eight-planet] model have refused this term. They will tell you why. Listen carefully. The word planet is being restricted to just one narrow point of view. Their restriction means that a dwarf planet is not a planet. It would be like saying a dwarf star is not a star. We can fix this. Will we have too many planets? Will we confuse the public? No. The distinction is as simple as an umbrella. Pluto is a planet, but it is in the dwarf planet category. So please pa.s.s 5B. The word planet must be shared.

I almost felt bad enough to want to give in. I didn't object to dwarf planets being considered planets, which was all he was talking about. But I did object to the other planets being termed "cla.s.sical planets."

For the anti-Pluto side, a British astronomer stood up and spoke: The key issue is the definition of the concept planet planet. This is a very important decision to be taken by the IAU; Resolution 5A is very close to the definition that was agreed by consensus at the meeting on Tuesday. There it was made clear that 3 distinct categories were being defined. Planet, dwarf planet, and small solar system body. The amendment [5B] proposes to insert the word "cla.s.sical" in front of the word planet planet. It is inconsistent with the 1st paragraph of Resolution 5A. And it transforms 3 distinct categories into 2, planets and the rest, and that too has been made clear. In answer to the question, how many planets in the solar system? Resolution 5A gives the clear answer: 8. Resolution 5B implies at least 11 and soon several dozen. Both Pluto and Ceres become planets, and probably several main belt asteroids and several Kuiper belt objects as well. Resolution 5B not only removes a fundamental dynamical distinction for a planet, it is confusing and internally inconsistent. In my view it should be rejected.

Sadly, even though I was all in favor of rejecting the resolution, I found almost none of the arguments compelling. Who cared what the consensus was on Tuesday? The final vote was today! And really, if the concepts were significant, wasn't it more important to make sure to get them right than to worry about the precise wording of the resolution? Besides, would it matter if there were eleven or more planets? It wasn't the number that mattered, it was getting the concepts right. I realized that I wouldn't have minded if there were "major planets" and "dwarf planets" instead of "cla.s.sical planets" and "dwarf planets." I guess my own version of pickiness was just as bad as anyone else's.

The vote was called. If the resolution pa.s.sed, Pluto would be a planet again, and Xena would officially be part of the club. Chad, David, and I would be the only living discoverers of a planet in the world. At least for now. And still I didn't want it to happen.

"All in favor of the resolution?"

Astronomers in favor of 5B-in favor of repromoting Pluto-held up their yellow cards. There were many. The counting took a few minutes.

"Mister President, we report ninety-one votes in favor."

That didn't seem like enough, but I couldn't tell from the tiny webcast precisely how many astronomers were there in the auditorium.

"All opposed to the resolution?"

Astronomers opposed to 5B, who wanted to firmly cap the solar system at eight planets, held up their cards. A sea of yellow filled the auditorium, which immediately erupted in applause.

"I think, Mister President, a further count is not honestly needed."

"Then it's clear that Resolution 5B is not pa.s.sed."

At that point it was final. And I said to the a.s.sembled press: "Pluto is dead."

The cameras whirred; correspondents talked into their microphones; on a screen on the other side of the room I could see myself on some local television station repeating, like an echo, "Pluto is dead."

Most of the remainder of the day was a blur of interviews, condolences, and congratulations. That afternoon I made my way to the studio of a radio station, where I was scheduled to be on a call-in program broadcast throughout Los Angeles. When I showed up at the studio, they told me that another astronomer would be calling in as a guest.

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 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 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 cla.s.sification.

Cla.s.sification 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 cla.s.sify. As more and more things are discovered, the cla.s.sifications will then be modified or revised or even discarded to better fit what is being observed and what they are trying to understand. Cla.s.sification 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 cla.s.sify 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 s.p.a.ceship traveling from a distant star to the sun. You don't know that planets exist. You don't even have a word for planet in your language. All you know is your s.p.a.ceship and the stars you can see surrounding you. The sun-which originally looked like any other star-now gets brighter and brighter as your destination nears.

As you start to stare at and wonder about the sun, you suddenly notice that-wait!-the sun is not alone! You see that there is something tiny right next to it. You're excited beyond alien words. As your s.p.a.ceship gets closer and you look even more carefully, you suddenly realize there are two two tiny things next to the sun. No, three. No, four! tiny things next to the sun. No, three. No, four!

You have just found the things that we call Jupiter, Saturn, Ura.n.u.s, and Neptune: the giant planets. From your perspective, still quite far from the solar system, they look tiny and so close to the sun as to be barely distinguishable. You don't have a word to describe them, so you make one up in your alien language: Itgsan.

You keep looking for a fifth Itgsan out beyond that fourth one you found, because it seems logical that there should be more, but even as your s.p.a.ceship gets closer and closer to the system, you don't see anything out there. Trust me, I understand your disappointment.

Finally, as you get close and the four Itgsan get brighter and appear more distinguishable from the sun, you realize you were looking in the wrong place all along. There are are other things next to the sun, but they are other things next to the sun, but they are inside inside the first Itgsan, not outside. There are four of them, but they're much smaller than the first four things you found. So you come up with a new word. You call them Itrrarestles. You don't know it, but you've just found Mercury, Venus, Earth, and Mars. the first Itgsan, not outside. There are four of them, but they're much smaller than the first four things you found. So you come up with a new word. You call them Itrrarestles. You don't know it, but you've just found Mercury, Venus, Earth, and Mars.

For a very long time, as you keep getting closer, there is nothing new. Finally, when you're almost on top of the solar system, you realize that between the small Itrrarestles and the large Itgsan there is a band of millions and millions of tiny things going around the sun. And looking even more carefully, you see that outside the large Itgsan there is another band with even more. You call them something that I can't p.r.o.nounce, but I call them the asteroid belt and the Kuiper belt.

Nowhere in that alien brain of yours would it be likely to occur to you to take one or two or even a few hundred of the things sitting in the Kuiper belt or in the asteroid belt and put them in the same category as the big things, the Itgsan and the Itrrarestles. Instead, you would quite rationally declare that the solar system was best cla.s.sified by four major categories. And you would, I think, be correct.

The only thing wrong with our current cla.s.sification of the solar system as a collection of eight planets and then a swarm of asteroids and a swarm of Kuiper belt objects is that it ignores the fundamental distinction between the terrestrial planets-Mercury, Venus, Earth, Mars-and the giant planets-Jupiter, Saturn, Ura.n.u.s, Neptune. In the cla.s.s on the formation of planetary systems that I teach at Caltech, I try to convince my students that, really, there are only four four planets and that Mercury, Venus, Earth, and Mars shouldn't count. But even students who worry about their grades aren't willing to go that far. So, even though the aliens call them Itgsan and Itrrarestles, we'll lump them together and just call them all Tsapeln. planets and that Mercury, Venus, Earth, and Mars shouldn't count. But even students who worry about their grades aren't willing to go that far. So, even though the aliens call them Itgsan and Itrrarestles, we'll lump them together and just call them all Tsapeln.

You can cla.s.sify anything at all in many different possible ways. If you are studying birds, you might split them into land birds and seabirds; carnivorous birds and seedeaters; red birds, yellow birds, black birds, and brown birds. All of these distinctions can be important to you, depending on what it is you are studying about birds. If you are studying their mating habits, you might cla.s.sify them in categories of monogamous and polygamous. If seasonal migration is your thing, you could cla.s.sify them by those that stay put and those that fly south for the winter.

Things in the solar system can equally well be categorized in many different ways. Things with atmospheres. Things with moons. Things with life. Things with liquids. Things that are big. Things that are small. Things that are bright enough to see in the sky. Things that are so far away that only the biggest telescopes will ever see them. All of these are perfectly valid categories, and they might be of utmost importance to you if you study one specialized type of thing about the solar system. As with birds, your favorite solar system cla.s.sification will depend on your interests.

Most people, though, don't have specialized interests in the solar system. The only cla.s.sification scheme they will ever know is the word planet planet. They will know what a planet is and how many planets there are and what their names are. Their entire mental picture of what the solar system is, of how our local bit of the universe is put together, will be carried in the understanding of that simple word. The definition of the word planet planet, then, had better carry with it the most profound description of the solar system possible in a single word.

If you think of the solar system as a place consisting of eight planets-or, better, four terrestrial planets and four giant planets-and then a swarm of asteroids and a swarm of Kuiper belt objects, you have a profound description of the local universe around us. Understanding how such a solar system came to be is one of the major tasks of a wide range of modern astronomers. If, on the other hand, you think of the solar system as a place with large things that are round and smaller things that are not quite round, you have a relatively trivial description of the universe around us. There is nothing important to study here: We've known for hundreds of years that gravity pulls big things in s.p.a.ce into the shape of a sphere.

Sometimes you don't even have to go through such extensive arguments. If you catch a person early enough, before the idea that Pluto deserves to be a planet has sunk in, you can teach things correctly from the start. Take Lilah, for example. Everywhere I went in the months following the IAU decision, people wanted to know if I thought Pluto had been treated fairly. Did I think Pluto was a planet? After a few weeks, I taught Lilah to answer for me.

"Lilah, is Pluto a planet?" I would ask, beginning our ch.o.r.eographed banter.

She would frown and shake her head.

"No no no no no no no."

As she got older the banter continued: "So what is is Pluto, Lilah?" Pluto, Lilah?"

"He's not a real dog. He's a dwarf dog."

My friends would laugh, and then invariably go out and buy Lilah Pluto toys. She has stuffed dogs, of course, but also a collection of nine-planet memorabilia. Early on she learned to figure out which one of the nine little circles on whatever picture she had was Pluto and then promptly declare, "Pluto is a dwarf dog." The continued laughs from that line were more reinforcement than I could possibly have given.

Another friend was worried how Lilah would react when she got older and discovered that I was a planet killer. "What will Lilah think," the friend said, "when she learns that Pluto is not a planet and that you are to blame?"

"I know what's going to happen," I replied. "In second grade or third grade, when she learns about planets she'll come home and say, 'Daddy, today we learned about the eight planets,' and I'll say, 'Lilah, did you know that when you were born we thought there were nine or even ten planets?' She'll look at me, shake her head, and say, 'You know, adults are so stupid so stupid.'"

Now that Xena, too, was officially called a dwarf planet, it finally got a real name. The possibilities were wide open, but Chad, David, and I had decided that because-at least in our minds-Xena had been the tenth planet in good standing for an entire year, we wanted to give it a Greek or Roman name, like all of the other planets have. The problem was that there were very few left to go around. Back in the 1800s, when asteroids were first being discovered, they were, of course, called planets. And people wanted them to have Greek or Roman names, like the other planets. So they used up almost all of the major G.o.ds and G.o.ddesses and most of the minor ones, too. Every time we found a name we thought might be nice, we had to look it up in the databases of asteroid names to see if it had been used. Usually it had been. Finally, David wrote a quick computer program to correlate all asteroids with all names of Greek and Roman G.o.ds so we could see what-if anything-was left.

There wasn't much, and what there was was hardly recognizable. Obscure demiG.o.ds of long-forgotten activities. Minor protectors of long-gone professions. But one name grabbed my attention. I remembered this name from my high school mythology readings, and I couldn't believe no one had used it before. Here was a major G.o.ddess with a fascinating backstory, overlooked in the solar system for two centuries. I quickly double-checked all of the asteroid databases. I double-checked that my mythological memory was correct. And then I sat down and wondered, for the first time since I had correctly predicted my sister's pregnancy, whether or not there was some sort of cosmic force governing the stars and planets and even the dwarf planets after all. Maybe there was some sort of fate that had kept this name free until now, the perfect time for it to be unveiled. Maybe there was no free will in any of this. That idea is, of course, crazy, but it's hard not to think crazy thoughts now and then.

I quickly e-mailed Chad and David, and we all agreed: the largest dwarf planet, temporarily nicknamed Xena, cause of the largest astronomical showdown in generations and the killer of Pluto, would henceforth be called Eris, after the Greek G.o.ddess of discord and strife.

I love the myth of Eris. As a perpetrator of discord and strife, she was not everyone's favorite G.o.ddess to have around, so when the human Peleus and the sea nymph Thetis decided to wed, they didn't invite her to the wedding. I understand their dilemma. Having gotten married myself, I know that there are always touchy issues involving the invite list. There are A lists and B lists and whole categories where you think, "Well, if I invite one person from this category, I should really invite everyone everyone from this category," and then the bar tab gets out of control. If you find yourself having a wedding and are trying to decide whether or not to invite the G.o.ddess of discord and strife, my only recommendation to you is that if you decide from this category," and then the bar tab gets out of control. If you find yourself having a wedding and are trying to decide whether or not to invite the G.o.ddess of discord and strife, my only recommendation to you is that if you decide not not to invite her, make sure that she is not the to invite her, make sure that she is not the only only G.o.ddess who is not invited, which was the mistake Peleus and Thetis made. G.o.ddess who is not invited, which was the mistake Peleus and Thetis made.

The G.o.ddess of discord and strife doesn't take snubs lightly. She crashed the wedding anyway, and to cause, well, discord and strife, amid the guests she rolled in a golden apple on which she had inscribed "Kallisti," meaning "to the fairest." As Eris had planned, all of the G.o.ddesses at the wedding got into a fight over who was the fairest and most deserving of the apple. They asked Zeus to decide. But Zeus, being no dummy, took the rather dim-witted mortal Paris, put him on the throne, and asked him to decide. The G.o.ddesses, being no dummies either, knew that they had best resort to bribery. Hera offered Paris domination over men. Athena offered Paris victory in battle. Aphrodite offered the love of the most beautiful woman in the world. Paris didn't have to think twice about that one and promptly handed Aphrodite the golden apple. Aphrodite then mentioned the fine print: The most beautiful woman in the world now did indeed love him, but she was married and living in Greece, and the Trojan Paris would have to go abduct her. He did, but the other Greeks didn't take it well. The decadelong Trojan War ensued.

I was sold, but I still had to name the moon of Eris. Gabrielle had been the obvious counterpart to Xena, but who went with Eris? I read through all of the literary mentions of Eris from the past. I pondered geographical considerations. I looked at family ties. I was in search of something very specific; I had a plan that I had told n.o.body. Again, fate intervened, and I found precisely what I was looking for. I sent the proposed name of the moon to the IAU, and I told no one.

At home that night, I told Diane all about Eris. She thought it was a fabulous name. "What about the moon?" she asked.

"It's a surprise," I said. "A surprise for you."

When the name Eris was announced in the press a few weeks later, many people who had been following closely got what they took to be the inside joke on the name of the moon. I had called the moon Dysnomia. Dysnomia was one of the children of Eris, and she was the daemon spirit of lawlessness. Xena on TV had been played by Lucy Lawless. People a.s.sumed that Dysnomia was a sly nod to that original nickname.

I was happy to take credit for the wordplay, but in reality it was an accident that I hadn't even noticed until someone pointed it out to me. I'll just chalk that up, once again, to cosmic fate.

On the day that the names were announced, I couldn't wait to get home to tell Diane.

"I named the moon for you," I told her.

"You named the moon Diane?" she asked.

I explained that since the name Diane had long ago been taken by an obscure asteroid, I had had to be subtle. When Jim Christy discovered Pluto's moon, he took the first syllable of Charlene-his wife's name-and made a name out of it that's found in mythology: Charon. In searching for the perfect name for Eris's moon, I had looked for one that had the first syllable of Diane. Dysnomia is, admittedly, a bit clunkier than Charon, but there, in the first syllable, is my wife, Diane, whose family frequently calls her Di.

"Dysnomia is named for you," I said. "It's my present forever."

"Um, thanks, I think," said Diane.

After some contemplation, she added, "This doesn't excuse you from Christmas presents, you know."