How I Killed Pluto and Why It Had It Coming - Mike Brown (2010)


The next morning, January 1, 2005, my whole household woke up early to walk down to the Rose Parade, which winds its way through Pasadena every New Year’s Day. In the still-dark early morning I was awake in time to find Jupiter bright in the sky before the sun came up. Jupiter, Saturn, Uranus, Neptune, Pluto. That was it: the end of the planets.


Unbeknownst to anyone—well, except for Diane, to whom I told everything, and my parents, who were visiting, and all of my students, and a few friends here and there—two days after Christmas I had discovered the brightest thing I had yet seen. I didn’t know for sure how big it was, so I was not in time to win my bet, but something that bright might well be a planet. In honor of the season when it was discovered, I called it Santa.

A few years earlier, my first reaction to the discovery of Santa would have been: I bet it’s bigger than Pluto! I’ve finally found the tenth planet! By now, though, I was a bit more skeptical. Quaoar and Sedna had both fooled me with their anomalously frosty surfaces, which made them appear much brighter than I expected. But even if Santa’s surface was as anomalously frosty as Sedna’s, it would still mean that Santa was the size of Pluto. But what if Santa were even frostier? What if Santa was covered in, say, pure ice, which would make it even shinier and brighter than Sedna? I wasn’t going to get my hopes up too much.

I sent e-mails to Chad and David telling them what we had found. I was careful not to definitively declare the discovery as bigger than Pluto, but I did mention that if it had a dark surface—as we had long assumed most objects in the Kuiper belt did—it would have to be almost as big as Mercury.

Over the next week, Chad, David, and I raced to see who could find old pictures of Santa to figure out what kind of orbit around the sun it had. Chad won and declared the orbit thoroughly normal. “Normal” in the case of the Kuiper belt means elliptical and tilted, but still within the swarm of all of the other Kuiper belt objects. After the oddness of Sedna, this normal orbit was almost a relief. At least something about the Kuiper belt was making sense.

Today I know Santa by its official name, chosen by David: Haumea. The mythological Haumea is the Hawaiian goddess of childbirth. Her many children, which compose a large subset of the population of Hawaiian deities, were broken off from different parts of her body. The astronomical Haumea has been equally prolific. In the years since its discovery, we have found many other objects in the outer solar system that we can now trace back to having originally been part of the surface of this object. We think that at one moment early in the history of the solar system, a much larger Haumea was smashed by another icy object in the Kuiper belt traveling at something like ten thousand miles per hour. Luckily for Haumea and for astronomers today, the impact was only a glancing blow. Had it been more head-on, Haumea would have thoroughly shattered and dispersed to the ends of the solar system. Instead, the glancing blow left the center of Haumea mostly intact, but large chunks of the surface went flying into space, while Haumea itself was left spinning faster than almost anything else in the solar system. Some of the chunks that were blasted off the surface didn’t go far; at least two are now in orbit around Haumea as small moons (when we first discovered these we called them Rudolph and Blitzen, but now they are named after children of Haumea: Hi’iaka, the patron of the Big Island of Hawaii and the goddess of hula, and Namaka, a sea spirit). Many more of the chunks were blasted so hard that they escaped Haumea entirely and now form a virtual cloud in orbit around the sun.

It also turned out that I was right not to get my hopes up about the size of Santa/Haumea. We learned that Haumea is covered in pure ice, and it is smaller than Pluto.

None of this was obvious when Santa/Haumea was first discovered. It just looked like a normal, albeit extra-bright, object in the Kuiper belt. David was the first to notice something strange: It got brighter and fainter every two hours, a fact that he quickly surmised was due to the fact that Haumea was oblong and tumbling end over end every four hours.

Huh, we all said.

Next we discovered two moons.

Weird, we all thought.

It wasn’t until eighteen months after the discovery that the final pieces of the puzzle came together. It was around midnight at a beach hotel on the island of Sicily. Kris Barkume, another graduate student of mine, was going to give a presentation the next morning at an international conference on the subject of her Ph.D. thesis, which was a study of the many moderately bright objects that had been discovered by Chad, David, and me. One subset of these objects appeared unusually icy compared to everything else out there. I had asked her to concentrate on trying to understand what might be going on with those objects. By the midnight before her talk she had learned much, but she still didn’t really have an explanation. We sat down on the sofa in the lobby of the hotel so that she could go over her talk with me.

We kept looking at the data on the odd icy objects, and still no obvious explanation came to mind. Finally she said, “Oh, and you know what’s funny? Their orbits around the sun are almost identical.”

They are?

“Yeah, look. And you know what else is funny? Santa has almost the same orbit.”

In my scientific life, most of the discoveries come as the result of seeing something for the first time. A picture appears on my screen and I suddenly know something big is out there. I know no one has ever seen it before, and I feel that little charge. This time it was different. There was no obvious picture on the screen. We were just sitting on the sofa. But instead of a little charge, I felt a full jolt of instant understanding. It all suddenly made sense. Santa’s spin, Santa’s moons, the little icy objects flying around it: They were all caused by that one glancing blow millennia ago; the moons and the strange little icy pieces flying around were all the debris blasted off the surface in what we now know to be the largest impact in the outer part of the solar system. Ah ha!

Kris gave her talk the next day, skillfully laying out all of the pieces of the puzzle that we had just discussed the night before and reassembling them to tell the story of one of the most dramatic events in the known history of the outer solar system. Everyone gasped.

It took us years after the initial discovery of Haumea to find out all of these details. Even today we’re still studying Haumea and learning more and more. In the days following the discovery, back when Haumea was just Santa, I knew little more than that there was a big bright object out there waiting for me to study it in detail at the start of the year.

In addition to studying Santa, I had other things on my mind that New Year. Though I had pushed hard to finish looking at all of the old pictures to find really distant objects before the end of the year, I had not only run out of time, I’d run into distraction. I admit that I spent less time thinking about the science of the outer solar system than I did worrying about the science of embryonic growth and early childhood development. Hours that could have been spent staring at pictures of the night sky were spent, instead, reading about statistics of timing of childbirth and first smiles. I was still obsessed; I had just changed the main object of my obsession.

•   •   •

I had been at work on January 5 for only a few hours when I decided to get up and take a walk. I needed to walk down the street and get some lunch. I had some things to think about. Lunch that day was the same as lunch most every day. I went to the same busy corner just down the road from my office; I ordered the same sandwich from the bagel store; I sat staring into the same steaming cup from the coffee shop next door. I like things that stay the same. The sun was shining and the seats on the outside patio were packed and everyone was emerging for a several-day break in the record-setting rains that were pummelling southern California that winter. From my spot on the patio I could see the temporarily snow-covered peaks of the San Gabriel Mountains just a few miles to the north. To me, there is almost nothing more relaxing and serene than this particular cup of coffee drunk at this particular spot on the planet Earth at this particular moment in the year, when the winter storms have come from across the Pacific Ocean and cleared the skies and coated the mountains, and the sun, low even at high noon in the clear skies just a few days after the winter solstice, is shining on the tables outside and quickly melting the snow on the mountains beyond.

I particularly like the stability and predictability of this spot when I know that everything is about to change. I sat in this same spot staring at these same mountains in the last hour before my wedding, thinking about the future, thinking about the past, suddenly remembering that I had left my bow tie at home. It was the same spot where I sat with Diane for hours on a workday and realized that she was choosing to stay and sit with me rather than going back to work and that I had been stupid all along. Later, I sat in the same spot with Antonin Bouchez as he convinced me not to quit searching the skies. And, though I didn’t know it at the time, six months from now I would momentarily pause at this same spot—no time for sitting now!—as the last stop as I was taking Diane to the hospital for the birth of our Petunia, thinking only about the impending present and how long the night ahead was going to be.

This clear January day, one in which I watched the waterlogged people enjoy the fleeting sun and stared at the snow quickly melting on the mountains, was a day I would remember as well as those other momentous days at this spot. After sitting on the patio, drinking my coffee, and staring one last time at the mountains, I walked back to my office, sat down at my desk, and carefully composed a short e-mail that I knew would set in motion a series of events that would lead to a change in our view of the solar system. Eventually the news would spread across the planet, but, for now, I sent copies to only two people: Chad, 2,500 miles west of me on the Big Island of Hawaii, and David, 2,500 miles east of me at Yale University. They were about to become just the third and fourth people in history to know what I had known for several hours (Diane was, of course, the second) and had been thinking about as I stared at the mountains over lunch: The solar system no longer had nine planets.

When I had left home to go to work that morning, the nine-planet solar system was still intact. Sure, the discovery of Santa was exciting, but given our track record of discovering things that turned out to be smaller than Pluto, I was pretty sure that Santa would be, too. It seemed likely that the solar system would retain nine planets. It seemed likely until I sat down at my desk that morning and discovered the tenth. There it was, moving across the sky, visible on a series of pictures blinking across my computer screen. Two weeks after the discovery of Santa, the almost-planet, I had found the real thing.

There aren’t many chances in life to write an e-mail like the one I sent to Chad and David. I’d thought all through lunch about how exactly I would word it. I went for carefully calculated obscurity:

Subject: why we get up in the morning

And then I went on, staccato style:

new bright object

please sit down and take a deep breath

mag = 18.8, making it brighter than anything out there except Santa

distance = 120 AU

and, by the way, if you moved Pluto to 120 AU it would be about mag 19.7

That’s all they needed to know to understand that the solar system was, from that day on, a different place. To most people, all of this would be more or less nonsense (at least I hoped, in case there were prying eyes; I was, I thought, overly paranoid, but in the end it turned out I was not nearly paranoid enough), yet Chad and David would instantly see the significance of each of the lines.

new bright object

We had just discovered Santa two weeks earlier, and I was sure they would assume that was the object I was referring to. What else would I be writing about? No one expects the next one to come so fast.

please sit down and take a breath

Okay, I have a melodramatic streak.

mag = 18.8, making it brighter than anything out there except Santa

Astronomers describe the brightness of their objects in “magnitudes,” and “mag = 18.8” immediately told Chad and David that the new object was bright, at least for something out there in the region of Pluto. But this was only the second-brightest object we had found to date, and it wasn’t even as bright as Pluto. The next line was designed to get them to fall out of the seats that I had previously asked them to sit in.

distance = 120 AU

The phrase “120 AU” means 120 times the distance from the sun to the earth, or about 12 billion miles. Even to astronomers, the phrase “12 billion miles” generally means nothing other than “really far away.” But 120 times the distance from the sun to the earth is packed with meaning. It is farther than anything that had ever been discovered in orbit around the sun, and almost four times more distant than Pluto. Finding something at this distance was a major discovery, regardless of what it was. But something so far away would be expected to be so faint that it would be just barely visible in our telescope. This object was not just barely visible, it was almost the brightest thing we had ever discovered. The brightness (“mag = 18.8”) combined with the distance (“distance = 120 AU”) meant that I was writing about something that must be larger than anything we had found in all of the previous years of our searching. The next line of the e-mail drove the point home, in a feigned attempt at nonchalance:

and, by the way, if you moved Pluto to 120 AU it would be about mag 19.7

Pluto is much closer to us and to the sun than this newly discovered object, so it appears to be much brighter; but if you moved Pluto out to the same distance as the new object it would be almost three times fainter than the new object (which, in astronomers’ archaic system, would mean that it had a higher magnitude). If you have two objects at the same distance from the sun and one is brighter than the other, chances are that the brighter one is bigger than the fainter one. Chances were that the newly discovered object was bigger than Pluto. Chances were that the nine-planet solar system had just come to an abrupt end on that early January morning.

I pressed the “send” button on the e-mail and sat back to think about the significance. Nothing this large had been found in the solar system in more than 150 years; no person alive today had ever found a planet; history books, textbooks, children’s books would all have to be rewritten. But I don’t remember thinking any of those things. All I can remember thinking is that we were only five days into the New Year and Diane and I had, just a week before, told our parents and friends that we were expecting our first child; a week before that I had discovered Santa, which would eventually spawn the biggest astronomical controversy in years; and now I had found something bigger than Pluto.

Wow, I thought, this sure is going to be a busy year.

•   •   •

I sent one more e-mail that afternoon before diving in to learn what I could about the new object. It was to Sabine, the friend with whom I had made the bet five years earlier.

Would you be willing to grant me a five-day extension on our bet?

She said that she would.

By the end of the week, David had tracked the object down on some recent pictures he had taken, and Chad had followed it into the past for decades. We knew the orbit precisely. The orbit was, like that of Santa, relatively normal. It was scattered. It was so far from the sun right now only because we had caught it at its most distant point. It’s on its way back in but will take a while to get there. The object takes 557 years to go around a full orbit, so it will be half of that—278 years—before it is at its closest point to the sun. When that happens, it will be closer than Pluto and thus, presumably, brighter as seen from the earth. I can’t wait to see it.

Clyde Tombaugh found Pluto in 1930 but spent much of the following decades searching for whatever else might be out there in the distant regions beyond Neptune. He never found anything else. As the story is usually told, this was because he was using the old technology of photographic plates, which were simply not good enough to see what we now know as the myriads of objects out there. But we now know that the story is not quite so simple. If Tombaugh had been looking 278 years earlier or 278 years later, our new object would have been as bright as Pluto, and he would have found both.

It’s interesting to ponder what people would have thought in the 1930s if not just Pluto but also this new object had been found. Both are on crazy elongated orbits. Both appear significantly smaller than the giant planets. And their orbits cross. I’m pretty sure that the similarities to the asteroid belt discoveries 130 years earlier would have led everyone to conclude that these were simply the biggest members of what would turn out to be a huge population of similar objects. And they would have been right. Instead, though, the solar system was arranged such that at the time of the development of large photographic plates and the first major survey of the outer solar system, only Pluto was close enough to be seen. Too bad for us not to have been provided with such obvious clues to the nature of the outer solar system. But good for Pluto, since it got to be everybody’s favorite oddball planet for more than seventy-five years. Though it wouldn’t be for much longer.

We didn’t refer to our discovery as “this new object” for long. We quickly gave it a code name. Unlike Flying Dutchman or Santa, which were inspired by circumstances of the discovery, we had had a name waiting for this one for a long time. Since the earliest days of surveying the outer solar system with the photographic plates, I had always had a well-considered code name for the hypothetical object bigger than Pluto. In coming up with the name, I had thought that it was best to keep the X for the apocryphal Planet X beyond Neptune. And I had thought that Venus shouldn’t remain the only female among the planets. And finally, I thought that the name should be mythological.

With those criteria, I was left, as far as I could tell, with only one choice. We called the new object Xena, after the eponymous heroine of Xena: Warrior Princess, the campy, female-empowered television take on Greek mythology starring Lucy Lawless. It was true that the name Xena was only TV mythology instead of real mythology, but as I liked to point out for the next eighteen months, as the name got more and more widely known, wasn’t Pluto named after a Disney dog? Whenever I made that joke publicly, about half the people in the room actually thought I was serious.

A few weeks after the discovery of Xena, Chad got a chance to swing the giant Gemini telescope, at the summit of Mauna Kea on the Big Island of Hawaii, in its direction. Chad now worked at that telescope, so getting a little time at the discretion of the director to look at something that was clearly bigger than Pluto was no hard task. When he looked at Xena’s surface, we had our first confirmation that Xena was something special. Xena looked like Pluto.

By “looked like Pluto” what I really mean, to be more precise, is that the sunlight bouncing off Xena contained within it the unmistakable signature of a surface covered in solid frozen methane. Nothing else in the Kuiper belt looked like this, with one exception: Pluto.

It was one thing to make the quick calculation to know that Xena was bigger than Pluto. But we had been looking at new Kuiper belt objects for a long time, and we had never seen anything that looked like Pluto.

I went home that night and told Diane about the methane.

“So it’s a planet?” she said.

“No,” I quickly pointed out. “It means Pluto is not a planet.”

“But if there are only two of them out there that look like this, and they both look different from everything else, why not just call them both planets?”

I went over my usual litany: Pluto was simply the largest—now the second largest!—member of a huge population in the Kuiper belt. Singling it out for special planetary status really made no sense at all.

“Okay, but think about your daughter.”


“Having her father discover a planet might mean that someday she’ll be able to afford college.”

Diane was joking. At least mostly.

I remained adamant.

She pressed: “Didn’t you used to joke that your definition of a planet was ‘Pluto is not a planet, but anything that I find that’s bigger is’?”

Yes. I had made that joke. But it was a joke.

Diane was in her energetic superwoman second trimester. If I was working late trying to figure out something about Xena or Santa, she would stay awake even later looking at baby magazines. If I woke up early to try to look at a few pictures of the sky just as they were coming off the telescope, she would already be awake looking at pregnancy books. As long as she was fed, she was unstoppable.

“But really, you are going to have people arguing that it is a planet, and you’re going to stand up and say, ‘No no no no’? If Petunia is a really cute child, will you go around and point out that, really, she is not so cute because, well, her nose is a bit big?”

Well, only if it is big.

“Don’t you think it would overall be better for astronomy to have new planets discovered rather than have old planets killed?”

I think it’s better to get it right.

“But don’t you think the public would be more excited and engaged in astronomy and in science if there were new planets being discovered?”

Enough, woman who needs no sleep! It is past my bedtime! But I will ponder your suggestions in the morning when I wake up, which will be long after you’ve already risen.

As winter waned to spring, three independent trains of thought ran through my mind. If I ever got to spend more than a few hours in a row thinking about one of them, I would suddenly sit up with a start and remember one of the others and start thinking about that one, before I suddenly remembered the third, and then the process would start all over again.

The first ticking calendar was strictly biological. Petunia was getting bigger. Her bones were hardening. Her eyebrows were growing. She had a July 11 due date, and though there was not much I could do to influence anything, I could nonetheless obsess about what, precisely, a due date means. I asked anyone who I thought might have some insight. I know, for example, that due dates are simply calculated by adding forty weeks to the start of the mother’s last menstrual cycle. But how effective is that? How many babies are born on their due dates?

Our child-birthing class teacher: “Oh, only five percent of babies are actually born on their due dates.”

Me: “So are half born before, half after?”

Teacher: “Oh, you can’t know when the baby is going to come.”

Me: “I get it. I just want to know the statistics.”

Teacher: “The baby will come when it is ready.”

I asked an obstetrician.

Doctor: “The due date is just an estimate. There is no way of knowing when the baby will come.”

Me: “But of your patients, what fraction delivers before, and what fraction delivers after the due date?”

Doctor: “I try not to think of it that way.”

I propose a simple experiment for anyone who works in the field of childbirth. Here’s all you have to do. Spend a month in a hospital. Every time a child is born, ask the mother what the original due date was. Determine how many days early or late each child is. Plot these dates on a piece of graph paper. Draw a straight line for the bottom horizontal axis. Label the middle of the axis zero. Each grid point to the left is then the number of days early. Each grid point to the right is the number of days late. Count how many children were born on their precise due dates. Count up that number of points on the vertical axis of your graph and mark the spot at zero. Do the same with the number of children born one day late. Two days late. Three. Four. Keep going. Now do the early kids. When you have finished plotting all of the due dates, label the top of the plot “The distribution of baby delivery dates compared to their due date.” Make a copy. Send it to me in the mail. My guess is that you will have something that looks like a standard bell curve. I would hope that the bell would be more or less centered at zero. It would either be tall and skinny (if most kids are born within a few days of their due dates) or short and fat (if there is quite a wide range around the due dates). One thing I know, though, is that the bell would have a dent on the right side. At least around here, no kids are born more than a week or two after their due dates. Everyone is induced by then.

I am usually capable of allowing myself to give up on trying to get the world to see things in my scientific, statistical, mathematical way. But this mattered to me. If I was at a dinner party with Diane and the subject of due dates was broached, Diane would turn to me with a slightly mortified look in her eyes and whisper, “Please?” I would rant about doctors. About teachers. About lack of curiosity and dearth of scientific insight and fear of math. I would speculate on the bell curve and about how fat or skinny it would be and how much it might be modified by inductions and C-sections, and whether different hospitals had different distributions. Inevitably the people at the dinner party would be friends from Caltech. Most had kids. Most of the fathers were scientists. Most of the mothers were not. (Even today things remain frighteningly skewed, though interestingly, most of my graduate students in recent years have been female. Times have no choice but to change.) As soon as I started my rant, the fathers would all join in: “Yeah! I could never get that question answered, either,” and they would bring up obscure statistical points of their own. The mothers would all roll their eyes, lean in toward Diane, and whisper, “I am so sorry. I know just how you feel,” and inquire as to how she was feeling and sleeping and how Petunia kicked and squirmed. (As an aside, my female graduate students wanted to know the answer to my question, too, and were prepared to rant alongside me. Times have no choice but to change.)

There was another calendar ticking, too. At the moment, the sun was almost directly between the earth and Xena. We knew Xena was out there, but we couldn’t see it. When Chad had looked at the surface of Xena and realized it looked similar to Pluto, he had done so at almost the last possible moment. Xena had been low in the western sky just at sunset. A few weeks later Xena set with the sun, and we couldn’t see it anymore. But slowly, the earth was moving around the sun, and Xena was eventually going to reappear on the other side, this time in the early-morning sky. As desperate as we were to learn more about Xena, we had no choice but to wait. Our first chance to get a good look would not be until September. I made sure that we were scheduled to be at the Keck telescope then. Other than that, there was little we could do except try to keep from telling people. I was looking forward to springing my news on an unsuspecting world.

But another calendar was ticking, too, this one involving two different moons. One of the people I had told about Santa was Antonin Bouchez, the former graduate student of mine who had convinced me not to quit two years earlier. He now worked at the Keck telescope helping to develop a fancy new technologically intensive way to make extra-sharp pictures with the telescope. Usually, when you take a picture of a star or planet or anything else with a telescope, the earth’s atmosphere blurs that object a little bit, preventing you from seeing the smallest details. This blurring was the reason that we were never certain at first how big the things we kept finding were; their little disks were blurred out enough that they all looked the same. Antonin had been hired to work on a project to fix this problem. The trick is to take a powerful laser and shoot it out the front of the telescope into space. The light from this laser traverses the earth’s atmosphere, and then, right when it is about to shoot out the top, it encounters a thin layer of gas that has been burned off from asteroids as they enter the earth’s atmosphere. The laser light is precisely tuned to bounce off the asteroid gas and return back to the earth. If you then take your telescope and point it right at the location of the laser, you see a little spot of light—an artificial star!—in the sky. The real trick then happens. You take that picture of the laser beam, which has been distorted by the earth’s atmosphere, and you bounce it off a fun-house mirror that is warped precisely so that the picture of the laser is as sharp as you know it is supposed to be. And then you do it all over again one-hundredth of a second later, using a different fun-house mirror shape, as the roiling of the earth’s atmosphere distorts the laser beam differently. If you can get all of the laser light going in the right place and the computers calculating fast enough and the fun-house mirrors warping accurately at your command, you can then take a nice long picture of the sky, and you will see a beautiful pinpoint of a laser beam, just as you shot it. That would be a lot of work just to see a laser beam; but if you pointed the laser beam directly at something else in the sky that you really cared to look at, you would also be perfectly correcting the light coming from that object, too.

One of the very first times that Antonin and the rest of the team hard at work at the Keck Observatory got all of the pieces in place and pointed up to the sky to test things out, they looked at Santa—and they found that Santa has a moon. We named it Rudolph.

Discovery of moons is extremely helpful, since it means that you can weigh the object using simple high school physics. Once you know how far away the moon is from the object and how fast it goes around the object, you’ve got all the information you need. Now that we knew that Santa had a moon, we only had to observe it a few more times and we would know how fast it was moving and how far away it was.

For me, all this meant was a lot of waiting. The first ticking clock was, strangely enough, that of our own moon. Because the laser system that Antonin was working on was still experimental, no one wanted to potentially waste the most valuable observing time. The laser was allowed to experiment on the telescope only when the moon was full—when it was bright time and many of the astronomer’s favorite targets in the sky were washed out by the glare of the moon. So though we knew about the moon of Santa quickly, we didn’t get our second look until twenty-nine days later, when the earth’s moon came around full again.

After twenty-nine days Rudolph had moved, but we now had no idea if it had gone around several times and come back or if this was still its first revolution. We had to wait twenty-nine more days to get our next look. At this point it was close to where we had seen it the first time. This would all make sense if the moon took about fifty days to go around Santa, but I couldn’t be certain for twenty-nine more days. The fourth time we saw it, we knew for sure: Rudolph goes around Santa every forty-nine days. It took one final measurement for confirmation to make sure we had the distance down, too. Combining the time period of the orbit with the distance from Rudolph to Santa allowed us to know that Santa weighs only one-third as much as Pluto. It was a relief, almost. We had finally been careful not to get our hopes up too much.

Just because there was Santa’s moon to track and due dates to fret about and Xena to anticipate, it didn’t mean that new pictures weren’t rolling in every night.

The universe speaks to me in strange ways. One day when I was in graduate school, two of my best friends who didn’t know each other separately told me that they were each expecting their first child. Strange, I thought, when the second friend told me. What could this mean? What is the universe telling me? I thought about it for a while and came to the conclusion that, clearly, this meant that my sister, who had been married for several years by this point, must be pregnant. What else could the universe be trying to say? I talked to my mother that very night.

“I think Cammy is pregnant.”

“What?” my mother replied. “Have you just talked to her?”

“No, the universe told me.”

My mother never quite knows how seriously to take me.

When my sister called my mother the very next day and said, “Mom, guess what?” my mother said, “You’re pregnant.” My sister was extra flabbergasted when the answer to “How did you know that?” was “Mike told me.”

When my sister called me, she asked, “Are you studying astronomy or astrology?”

Apparently my communication with the universe is not always so reliable—I just missed the signs this time. Petunia was growing. Rudolph was revolving around Santa. Xena—mighty Xena!—was swinging toward the night sky. The universe was presumably trying to warn me what I didn’t learn until April 3. While sorting through pictures from a few nights earlier I saw the brightest thing on my screen ever. Brighter than Xena. Brighter than Santa.

“Here we go again,” I thought.

The subject line of the e-mail that I sent to Chad and Dave was:

raining = pouring

It was raining so hard that I was in danger of drowning.

We named this new object, found two days after Easter, Easterbunny.

Easterbunny was so bright that it was probably bigger than Pluto, too, or maybe the same size. We quickly took a look at it with the Keck telescope and realized that, like Xena, Easterbunny had a surface that looked like Pluto’s. The solar system had gone from one to two to three Pluto-like objects in just three months.

I almost felt bad. This was too much! How was I going to give everything the attention that it deserved? I needed a plan, now.

Our goal was to follow good scientific practice and announce the existence of these objects to the world with a full scientific account in a scientific journal. But full scientific accounts take time. We had done well with our previous discoveries. Quaoar had taken about four months from discovery to scientific paper. Sedna had taken about the same. We were pretty proud of our speed. But even if we could keep up the fast rate, we suddenly had Santa and Xena and now even Easterbunny to write papers about.

David and Chad and I made a plan. Santa had been discovered first, and we knew the most about it already. We would each write papers on different aspects of it. Whenever the first paper was finished, we would have a low-fanfare announcement. We knew that Santa was smaller than Pluto, and we didn’t yet know all of the details of Santa’s massive collision and debris field, so we thought there would not be too much interest in it for the public. My goal was to get a paper on Santa finished before the birth of Petunia, since I still had a little free time. Her due date was now only three months away.

We would then save the big excitement for Xena and Easterbunny, which were sure to cause a stir. We were scheduled to be at the Keck telescope in September to get a first really good look at Xena. With some intense work we could have a scientific paper ready a month after that (the delusions of first-time parents astound me to this day) and make the announcement around the beginning of October. I liked this back-to-school timing, as I thought having the announcement of one or two new objects bigger than Pluto would be the sort of thing that schoolkids would think was cool to talk about in class.

The plan required writing perhaps the three most important scientific papers of my life in under six months while having my first child. No problem, I thought.

Diane was having that last spurt of energy that comes in the weeks before delivery. The spare bedroom, which for years I had dubbed the “bike and computer room,” was suddenly transformed, with a crib and pale green walls and a collection of infant clothes waiting for an owner. I acquired a bit of sympathetic energy and redoubled my writing efforts so I, too, would be ready for Petunia. We were going to pull it off, as long as everything went as planned.