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


Even today I spend much of my time exploring the outer edges of the solar system, looking for little worlds that have never before been seen, wondering what else is out there on the outskirts of our solar system. Someday I will have looked everywhere that the telescopes I have are capable of seeing, and then I guess I will have to declare that my days of exploring are finished.

It will be nice to finally stop fretting every night when I see a few clouds in the sky as the sun goes down, or when the moon is nearing full and I know that the section of sky we wanted to cover this month is not quite done. It might be nice to wake up in the morning and see red-tinged cumulus clouds beautifully strewn across the L.A. basin and not have to wonder what we missed last night. And even though the computer does most of the hard work of looking at all of the data and finding the things that move, something always goes a bit wrong and I am always fixing a little bit of computer code or making slight improvements. The computer even sends me text messages on my cell phone when something goes really wrong. More often than not, it seems, trouble occurs on Saturday mornings while I am sitting drinking my coffee.

Still, the fact that on any morning I might walk into my office and see something moving across the sky that no one has ever seen before, something bigger than anything found in perhaps a hundred years, adds an element of excitement to my life. I will be sad to be done, and what will I do after that?

I did almost quit once, a little more than a year after the announcement of Quaoar. I thought, at the time, that we had reached the end of the solar system.

Chad had moved back to Hawaii by then, eventually to marry, buy a house on the rainy, steamy, jungly northeast side of the Big Island, and work on telescopes. He and I (though, really, mostly he) had spent two long years staring at the sky night after night, and by the end of the two years we had covered 12 percent of the whole sky. While this might not seem like a huge amount, this time we really had covered a wide swath of the parts of the sky where we expected anything big to be. If we looked farther north or farther south, we would be looking away from the region where all of the planets are. The only things that we would find in the regions farther north and south would be things that went around the sun in orbits even more tilted than Pluto’s. The chances that something like that was out there seemed remote.

I don’t mind taking bets on remote chances. Perhaps you could have said that our chances of finding something as big as Quaoar were remote, too, but there it was. The chances I would meet the person that I was going to marry in the basement of the 200-inch Hale Telescope were even more remote, but by now Diane and I had been married almost six months. Remote chances lead to good things, as far as I can tell.

So in the fall of 2003, just as Chad was leaving and our two-year project to use the little telescope at Palomar to scan the skies for planets was ending, I began a new project about which I was quite excited. I was going to use the same telescope to scan the skies for planets. For the third time. This time, though, I wasn’t going to concentrate on the most probable places, I was going to concentrate on some of the least probable. The project was going to be even better than before, too, because other astronomers had become interested in using the telescope to look at vast areas of the sky for very rare quasars flickering at the edge of the universe, and they had built an even bigger camera—the biggest astronomical camera in the entire world!—to look at even bigger areas of the sky at once. This seemed, at least at first, like great news for us. We would sweep through the unsearched regions of sky faster than ever before.

Right before Chad moved back to Hawaii, he modified all of the computer programs he had written over the previous three years so that they would work with this new supercamera. He automated everything as much as possible so that the project could continue in his absence. I was a little nervous about this, because it meant that I was stepping in to be the one in charge of the night-to-night workings of the project. I had been letting Chad take all of the major responsibility for years now, and in that time, I’d had many other projects going on to worry about and spend my time on. But things looked good. It looked as though with just a little bit of babysitting from me everything would run smoothly, the skies would be ours, and I could keep my day job.

The new camera arrived about a month after Chad left, and it spent its first night taking pictures of the sky. At the end of the night, I set Chad’s computer programs to search once again for distant planets, for things that were moving in the sky. The computer worked all day long, as I carried on with all of the nonplanet-searching projects that were supposed to be occupying my time. Finally an automated e-mail informed me that the program was done. I opened up the file to see if the program had found anything. It had! Not only had it found things moving in the sky, it had found thirty-seven thousand of them!

My heart sank.

There could not possibly be thirty-seven thousand real moving objects in pictures from that night. In fact, I now know that there was precisely one.

The computer was confused. But it was not Chad’s program that was the problem, it was the fancy new camera. To make the biggest astronomical camera in the entire world at a price that was not astronomical, the builders had had to compromise a bit on quality. One of those compromises had led to an incredible number of smeared spots, dark blemishes, light dots, black streaks, and bright blots showing up in each and every picture of the sky. The computer doesn’t do a good job of distinguishing between bright blots or light dots caused by the camera and those caused by something actually in the sky. Those thirty-seven thousand moving objects were almost all camera junk.

I had not expected the computer or the camera to be perfect. I had anticipated that every morning I would have to look through some of the pictures to sort out the real objects from the fake ones. I had even taken the time to write a quick computer program to make this sorting extremely efficient; I could simply sit at my computer, press a single button, and a little postage-stamp-sized bit of the pictures from the previous night would appear on my screen. Three images would blink through in succession, and by eye, I would quickly be able to see what the computer had thought was moving. The eye is really good at finding the computer’s mistakes or verifying true finds. After some practice, I could look at perhaps as many as twenty different candidate objects in a minute. But to look at thirty-seven thousand would take me thirty hours straight for every one night’s worth of data. This was potentially a disaster.

I sent an e-mail to David Rabinowitz, an astronomer at Yale University, describing the problems. David had helped build the new camera and had joined Chad and me as the third member of our planet search team; if anyone knew any clever solutions to the problem, it would be David. He quickly responded: There was nothing that could be done to fix the camera’s problem.

The only plausible solution I could think of was to somehow make the computer program much, much smarter. But Chad was on to a new job and new responsibilities and couldn’t spend the next two years writing new computer programs the way he had for the previous camera. And even if he was working on this project, I couldn’t think of an obvious way to make the computer program smarter. Everything that I could think of doing to get rid of the thirty-seven thousand camera-junk objects had a chance of getting rid of the real objects, too.

There was one solution: I could quit. Shut the project down. Declare an end to the solar system. In fact, it almost seemed like a good idea. Our chances of finding new objects were remote. The effort to find them was going to be extreme, if not impossible. If ever there was a time to cut our losses, now was it.

I needed a second opinion. I walked up the road to my favorite café with Antonin Bouchez, one of my graduate students at the time and someone whose opinion I greatly trusted.

“I’m done,” I told him. “We’ve looked at enough sky; if there was anything else out there, we would have seen it by now. The new camera is low quality, and I don’t think there is really any way to move forward.”

I laid out all of my reasoning. I outlined the regions of the sky we had covered. I talked to him about the very slim probability of finding anything else. I showed him data on the new camera.

“You’re crazy,” he said.

“No no no,” I told him. I went through the arguments again. Look at the problems with the camera! Look at how well we’ve already done with the sky!

“No, really, you’re crazy.”

We drank more coffee. I described how I believed the solar system was laid out and why it now seemed clear that there was nothing larger than Pluto out there to be seen. And thirty-seven thousand moving things to look at in one night? Impossible!

“Do you really believe there’s nothing else out there?” he asked.

“I do,” I said.

“So how are you going to feel when you pick up a newspaper one morning and read about someone discovering something right where you didn’t look?”

I was reaching for the coffee again but stopped short. “Uhhhhhh. But it’s not going to happen since we’ve reached the end of the solar system.”

“What if you’re wrong?”

What, indeed? Ten years earlier almost no one had thought that there was anything to be found beyond Pluto at all and that anyone spending all of his time looking was crazy. Even just two years earlier almost no one had thought that something as big as Quaoar would be found and that anyone spending all of his time looking was crazy. I hadn’t bothered believing what most people thought back then, so why was I bothering to believe what most people thought now?

“Do you really know there is nothing else out there?” Antonin asked again.

Well. Okay. No. I really didn’t.

“Then why exactly do you want to quit?”

Because it was going to be hard work. Because I didn’t have help anymore. Because I wasn’t certain I’d be able to pull it off alone. Because I had been working on it for a couple of weeks and had hit what felt like insurmountable roadblocks.

Looking back from a perspective of more than half a decade later, I think of this conversation as being as momentous as the moment when Diane walked through the door of the 200-inch Hale Telescope that first time that I saw her and my life irrevocably changed. A decade of floundering had ended that moment. This time the floundering had been for only a few months, but I had been floundering nonetheless. I can now even identify what the problem was, though I couldn’t have done so at the time. My biggest problem was not that the camera had specks or that the software was not up to the task. My biggest problem was that I had let myself become a normal person instead of an astronomer. I was believing what most people thought, because “most people” now included me.

When I hired Chad and set him to work, he was so good at it that I had spent most of the previous year or so enjoying my life. Most nights I even left work at an almost reasonable hour and went home and made dinner for Diane—and the nights I didn’t were usually because she was working late, not me. In the year before the new camera had been connected, Diane and I had married, gone on a monthlong honeymoon to South America, been on vacations, fixed up our little house. In short, we were behaving like normal people. I had never quite behaved like a normal person before.

I could do all of this because Chad was hard at work every night scanning the skies. And he periodically let me know how it was going. But, really, I didn’t know much about the details of what he was doing.

Now Chad had moved on to a new job, and I was left with a big complicated system that was suddenly mine alone. And a major component of the system had just changed, and everything needed to be fixed, and no one knew how to do it.

Antonin and I were still drinking our coffee. “Keep looking,” Antonin said. “How could there be nothing left to find?”

I had used that same argument myself. How could there be nothing left to find? How could this really be the end of the solar system?

I drank more coffee. I stared into space. How would I do it? There was no way I could get someone up to speed quickly enough to keep going. We were still scanning the skies every single night. I didn’t have the time to wait months or years for someone new to come on board to get things going. I needed someone right now.

And then I thought of someone who was actually pretty good at this sort of thing and even knew a bit about it already. Me. It would mean an end to being normal, to going home most nights and cooking dinner, but it would mean that the solar system didn’t have to end.

I finished my coffee, and Antonin and I headed back toward campus, but I took a quick detour to Diane’s office. She was between meetings. I told her about the problems and the 37,000 objects and about the solar system that I didn’t want to end and how the only solution was to start doing all the work myself. She looked at me, smiled, and said, “Go find a planet.”

In the end, the solution to what to do with 37,000 objects in one night turned out to be deceptively simple: I let it go. After a few more nights of collecting data and finding 33,000, 50,000, 20,000, and 42,000 objects, patterns began to emerge. Almost all of the camera junk turned out to be in a few places on the images. If I just threw some parts of the pictures away, ignoring what was there, then everything else was suddenly manageable. That meant, of course, that if something real was there I had to throw it away, too. But it was a price I was willing to pay. I finally settled on throwing away about 10 percent of the sky to get rid of 99.7 percent of the camera junk. For the first night’s worth of data, I went from 37,000 potential objects to look at to about one hundred. I could handle one hundred.

I spent a couple of long days and nights at my computer going through the two months’ worth of pictures that had accumulated while I had been figuring out what to do. Of that very first night’s one hundred objects, one turned out to be a real object out there in the Kuiper belt. It wasn’t the biggest we had ever seen—it was only about one-third the size of Pluto—nor did it really distinguish itself in any other major way, but there it was, a tiny little needle that I had found by throwing away only 10 percent of the haystack.

On one of those late nights when I was sorting through recent data, I found a bright Kuiper belt object; and then five minutes later, one more; and then five minutes later, a third. Again, they were not the biggest or the brightest objects, but it was clear we were in business. I let out a little shriek, which caused Emily Schaller—my graduate student who was working on Titan’s methane clouds—to stick her head in my office to see if everything was okay.

The objects I found didn’t look that special—the postage-stamp-sized picture just showed a single faint point of light moving slowly across a patch of sky full of stars. I don’t know if it was the fact that no one had ever seen this little world before, that something in the sky was moving, or that this thing I was seeing was near the edge of the solar system, but each discovery of one of those moving dots on my screen gave me a charge of adrenaline and a jolt of excitement. Even today, when I see one I want to grab whoever is in the hallway and sit him or her down in my chair and point. Look!

Over the next months, I barely kept my head above water. I was refining the software, making sure the telescope looked in the right places, flipping through a hundred or more images every morning, and still spending most of my time on the class I was teaching. My class that fall was called The Formation and Evolution of Planetary Systems, which taught graduate students current thinking on how the solar system is constructed. A lot of the time, the lectures focused as much on what we don’t know as on what we do. One of my favorite lectures was titled “The End of the Solar System”; it was where I got to talk about my own work in relation to the rest of the solar system. One of the mysteries I had been working hard on for the past few years was why the solar system seemed to end so abruptly. Yes, it continued on farther past Pluto than anyone had initially guessed, but about 50 percent farther than Pluto’s current distance from the sun everything came to an exceedingly abrupt end. Nothing had ever been found beyond this distance, and no one knew why. It is a mystery that still dogs and excites me today. I’ve gotten pretty good at ruling out almost any idea that anyone ever has. But I am just as good at ruling out my own ideas.

I’d prepared my lecture more quickly than usual the morning of November 15, 2004, since I knew the subject intimately. I had a few extra minutes before class, so I decided to look at the images from the night before. As usual, almost everything that showed up on my screen was an obvious mistake the computer had made. But after a few minutes, I stopped my quick flipping through images, because I had found one that confused me. A faint object moving slowly across my screen—more slowly, in fact, than anything I had ever seen before.

The speed with which an object moves in our pictures is directly related to how far away it is, in precisely the same way that when you’re looking sideways out the window of a speeding car, the things nearby zoom by quickly while the mountains in the distance appear to be just barely crawling along. The fact that this thing that I was looking at was moving at about half the speed of anything else I had ever seen meant that, if it was real, it would have to be twice as far away as anything anyone had ever found.

Most of the time when I find a real object, I know it right away. Most of the time, the thing that I see moving across the screen is unmistakably real. But this one was moving so slowly and was so faint that I couldn’t decide whether or not it was real. It could have been just a series of slight smudges that had coincidentally lined up but meant nothing. If you look at the sky for long enough, you’re bound to find such things. But what if it was real? What would it mean to find something so far away? I didn’t have any more time to think, because it was time for my class.

I gave my normal lecture. But at the end I couldn’t resist. After I told my students all about what we understood to be the edge of the solar system, I stopped, looked up, and added, “Maybe.” I told them that I had perhaps just found something that had changed all of that. But I wasn’t sure. And I would keep them posted.

I went back to my office and sent an e-mail to Chad and David. I tried to downplay the potential discovery:

Subject: amusement

I just found something that, if real, is at 100 AU. Wouldn’t that be fun?

Something at 100 AU—a hundred times the distance from the earth to the sun—would be more than three times the distance of Pluto and well beyond anything ever found in the Kuiper belt. Chad wrote back almost immediately:

If that one is real I’ll be buying the champagne.

Chad and I eventually drank that champagne. We were sitting on a beach on the Big Island of Hawaii, with the sun setting over the ocean in front of us, a pig roasting in a pit behind us. By entirely appropriate chance, Antonin, who had convinced me not to quit my search for a new planet, was there, too. We raised our plastic cups to an unending solar system.

•   •   •

This was it; something so far away that we could nonetheless see had to be big—almost certainly bigger than Pluto. It’s true we had been fooled by Quaoar at first—since it had had a much shinier surface than we had anticipated and was thus unusually bright without being as large as Pluto—but even if this new object had a surface as shiny as Quaoar, it would still have to be bigger than Pluto. Because it had been so elusive, we gave this new object the code name Flying Dutchman. The Flying Dutchman is, of course, the ghost ship of folklore that can never go home and is instead destined to sail the seas forever. We had no idea at the time what an appropriate name this was.

Since the Flying Dutchman—or Dutch, for short—was farther away than anything anyone had ever seen before, it certainly seemed to be part of a new, previously undiscovered part of the solar system. But I knew that there was another possibility. Even though Dutch was currently far beyond the Kuiper belt, it could still really be part of it. Sometimes objects in the Kuiper belt come a little too close to Neptune and get flung out onto long, looping orbits.

We do the same sort of flinging whenever we want a spacecraft to get somewhere in a hurry; we send it by Jupiter first to get a slingshot off the planet. The trick is to aim the spacecraft almost at Jupiter. The spacecraft gets closer and closer to Jupiter and is pulled faster and faster by the gravity of the giant planet, and then it just misses, skims the clouds, and now zips along at high speed toward its final destination. Jupiter is so massive that it has enough gravity to give an object a slingshot that will take it clear out of the solar system. The Pioneer and Voyager spacecraft went past Jupiter, took pictures, got the slingshot, and will never be seen again. Neptune, however, is too small to give a strong enough slingshot to propel something out of the solar system, so when it tries, the objects always come back. Many objects in the Kuiper belt thus have orbits that take them close to the orbit of Neptune but then much, much farther away from the sun. These objects have been called “scattered” Kuiper belt objects, as Neptune appears to have scattered them to those looping orbits.

Only small things get scattered. The large planets are on nice circular orbits because there is nothing big enough to kick them around. The objects in the Kuiper belt—including Pluto—have tilted, elongated orbits because they are too small to resist the bullying of Neptune. Dutch could well have been a scattered Kuiper belt object rather than something on a circular orbit like a planet. Maybe we just happened to be seeing it so far away because it was at the most distant point in its scattered orbit and would soon be making its way back toward the sun to show that it really belonged to the Kuiper belt region. Its orbit would be a clue to its potential planethood.

As we had with Quaoar before, we eagerly looked for pictures of Dutch that had been inadvertently taken by previous astronomers. Dutch was much fainter than Quaoar had been, so there weren’t nearly as many on which it showed up, but after a few days of careful searching we found it back a few years, which was enough to calculate what sort of orbit it had.

What was it going to look like? Circular, the way the orbits of massive planets should be? Scattered, like the orbits of many of the other smaller objects in the Kuiper belt? At first it was hard to tell. Although it is true that you need to figure out only where an object is and how fast it is moving to know an orbit, Dutch was so far away and moving so slowly that every time we measured it we came up with a slightly different answer. First we thought its orbit was circular; then we thought it was moving in a straight line and not even in orbit around the sun (that would be a first!). But after more care and measurement, we finally got the answer: Dutch was definitely not moving in a circular orbit, and it was definitely not moving in a straight line. The orbit was extremely elongated. So was Dutch at its farthest point in its orbit and moving inward like a normal scattered object would? No: just the opposite. It turned out that Dutch was at almost its closest point and moving outward. And its orbit around the sun appeared so elongated that it was going to take eleven thousand years to go all the way out and come back in again. It was the most distant object that humans had ever seen in the solar system, but it was eventually going to be even ten times farther away. Nothing was supposed to act like this in the solar system. It was neither a normal-seeming planet nor a normal scattered Kuiper belt object. There was nothing like it known anywhere else in the universe.

It’s sometimes hard to picture all of these orbits and what they mean. So try this. Take a sheet of copy paper, a pencil, and a quarter (or just follow along on the diagram on the next page). Put the quarter in the middle of the paper, trace its outline, and put a little dot at the center of the circle you have just drawn. This little dot is the position of the sun, while the outline of the quarter is the nice circular orbit of Neptune. Inside this circle is everything in the solar system that was known until the moment that Pluto was discovered in 1930. If you would like to put Pluto on your drawing, put your pencil at the four o’clock position of the circle of Neptune’s orbit and now draw an oval that starts and ends there, but while it goes all the way around the sun it reaches a distance almost but not quite twice the diameter of Neptune’s circle from the sun at the ten o’clock position (okay, if you’re being precise, get out your ruler and make Pluto go 19/16 inches from the center of your circle). Now you can draw the outer edge of the Kuiper belt: Sketch a rough circle all the way around the sun at the farthest distance of Pluto. Finally, shade in all of the space between Neptune and this outer circle. Now it is time to add a few scattered objects. Place your pencil at, say, a point halfway inside your Kuiper belt at the eight o’clock position. Now draw an oval all the way around the sun that starts and ends here but gets to a distance two or three times farther by the two o’clock position. Feel free to draw as many scattered objects as you like, just always make sure to start and end in the middle of the Kuiper belt before zipping off to the edges of the solar system.

Now you will need to draw Dutch. Draw a little dot about three times as far from the sun as the orbit of Neptune at, say, the one o’clock position (again, you precision freaks, put that dot precisely 2⅜ of an inch from the sun). You’re forgiven if, at this point, you would like to now draw an oval around the sun by coming into the Kuiper belt before going back out to your one o’clock position. But don’t do it. Dutch never gets much closer to the sun than where you drew it. Instead, take your pencil and draw an oval around the sun that starts and ends at the position of Dutch; but at its most distant point, at the seven o’clock position, the oval needs to be farther away. How much farther? Almost 33 inches—three times the full length of your 8½-by-11-inch paper! Dutch never touches the Kuiper belt. It never comes close to Neptune. And it spends most of the time so far away from the comparatively tiny region that is the Kuiper belt that from Dutch, the sun would be just an extrabright star in the sky. There is nothing else like Dutch.

Now take your paper and put it in a safe place for later study. It will be on the final exam.

Even though nothing like Dutch had ever been seen before, I had an idea about what it was immediately.

One of the benefits and joys of teaching a comprehensive class on something like The Formation and Evolution of Planetary Systems is that you learn an awful lot about the formation and evolution of planetary systems. Much of my day (and late nights and early mornings) is spent with the concepts that I want to teach spinning in my mind. I see and continuously rearrange the outline for whatever is my next lecture as I am lying in bed or driving home or cooking dinner or eating breakfast. I mentally go through all of the connections and logic and calculations to make sure they make sense.

On the very day I realized that Dutch was unlike anything else known in the universe, I was mulling over my next class lecture, which was about the origin of comets. Dutch had an orbit almost like that of a comet. Comets are tiny balls of dirty ice that come from far out in the solar system, quickly swing by the sun, and return again. Dutch did the same, but it never came nearly as close to the sun as a comet, nor did it go nearly as far away from the sun as a comet. Comets acquire their distinct orbits through a complicated dance with giant planets and passing stars, and—I quickly calculated—Dutch never comes close enough to any of the planets to be a partner in any such dance. But while working on my lecture for the day, I quickly realized that Dutch could have acquired its odd orbit if, when the sun was born 4.5 billion years ago, the sun was not an only child but, rather, simply one in a litter of many stars. Before all the other stars went their own ways, they could have pushed Dutch around and put it exactly where it is now. Astronomers had speculated about such things for decades and had argued back and forth about whether it was true, and I had just found the thing that was going to answer all of those questions for good.

Discovery is exciting, no matter how big or small or close or distant. But in the end, even better is discovering something that is capable of transforming our entire view of the sun and the solar system. Dutch was not just a chunk of ice and rock at the edge of the solar system. It was a fossil left over from the birth of the sun. And as surely as a paleontologist can take a fossilized bone of a T. rex and learn what the earth was like 70 million years ago, I was pretty sure that we could examine this fossil in space—this object that could have been put in place only near the very moment of the sun’s birth—and learn more about the sun’s earliest childhood than ever before.

That class was the most astounding I have ever taught. I carefully explained the steps and the calculations that show why comets are where they are and why something like Dutch—which they still didn’t know about—could not possibly exist, at least given the standard picture of the formation of the solar system. And then I showed them Dutch. Finally, I went through the same calculations but now with different conditions 4.5 billion years ago and showed that it would lead precisely to things like Dutch. QED. The students in the classroom dutifully took their notes, probably thinking nothing more profound than whether or not this would be on the final exam. Of course it was.

After Quaoar, I learned an important lesson. Names should be pronounceable. In the end, when it was time for a real name for Dutch, I settled on Sedna. Sedna is simple and easily pronounced, and has a serene sound to it.

The name Sedna comes from Inuit mythology. Since Dutch was so far away from the sun and was the coldest object anyone had ever seen in the solar system, I was looking for a name from an appropriately cold region. I quickly settled on Inuit as the closest polar mythology to my home in Pasadena. Sedna is the goddess of the sea. She lives in an ice cave at the bottom of the ocean, which seemed pretty cold to me. Plus the name has only two vowels—and they are not in a row. She does not, however, have a pleasant backstory.

In Inuit mythology, Sedna was a young girl who refused to marry any of her many suitors. Her father finally forced her to marry a mysterious stranger who couldn’t be seen beneath his cloak. The stranger was a raven, who took the girl back to his nest. Her father finally heard his daughter’s screams and, filled with remorse, crossed the sea in his kayak to rescue her. As he was paddling her away, the raven appeared and caused a great storm.

A typical story line in mythology goes as follows: The father sees the error of his ways and saves his daughter; the evil suitor attempts to take her back; the father vanquishes the suitor. In the Inuit myth, however, things go slightly differently.

The father, fearing for his own life, throws his daughter overboard into the storm and back to the raven. The girl begins to sink. She grabs the side of the boat to hang on to. The father takes out his knife and cuts off her fingers to keep her from climbing aboard. The girl sinks and becomes the goddess of the sea. Her fingers and thumbs become the seals and whales of the ocean. She is angry much of the time—understandably so—and causes storms to thwart the hunters. But she is soothed when a shaman swims to the bottom of the ocean and brushes her hair (having no fingers, she can’t hold a brush), and then she relents and lets hunters safely venture again. I hope Sedna is happier now, at the bottom of the ocean, and, especially, up in the sky, than she was with her creepy father or raven husband.

Contemporary Inuits make fantastical carvings of their mythological figures. The weekend before the press conference at which I was going to reveal Sedna to an unsuspecting world, I signed on to eBay and found that Sedna carvings could be had for a few hundred to a few thousand dollars. To celebrate the discovery, I bought what to me was a particularly nice—and particularly affordable—carving in which Sedna has the body of a seal, the arms of a woman, hands with no fingers, and a mermaidlike face. The Sedna carving sits in the center of my desk to this day, surrounded by other mementos of planetary discovery. The eBay bidding on the Sedna carving closed on Sunday night. The press conference was on Monday. By the end of the day on Monday, I checked and saw that prices of Sedna carvings had gone up by a factor of two. Yes! Maybe I had a future in Wall Street insider trading when discoveries in the solar system finally came to an end.

The name was a hit. I was surprised to discover that a good name with an interesting story behind it could lead people to have an emotional connection with an unseen object in space, though perhaps it shouldn’t have been such a revelation to me, given people’s attachment to Pluto. Quaoar never really caught on, but Sedna struck a nerve. Newspaper headlines proclaimed, “Welcome Sedna!” My mailbox began to be flooded with drawings from schoolkids who crayoned in nice red Sedna in the solar system right after Pluto. Astrologers quickly hit on the story of Sedna to declare that Sedna would herald a new feminine influence over environmental stewardship. Or awareness of child abuse. Though none of the astrologers agreed with one another, they certainly found the name and the story compelling.

The only problem with the name was that I had jumped the gun and broken the astronomical naming rules.

This was not the first time I had broken the rules. When I announced the discovery and name of Quaoar, it turned out that I had not sought approval through the proper channels in the International Astronomical Union. I didn’t realize that I was supposed to have tracked down the Committee on Small Body Nomenclature of the International Astronomical Union and proposed the name, allowing the august committee to deliberate and declare whether or not my name was appropriate. Luckily, the name Quaoar was perfectly appropriate, so the CSBN of the IAU promptly approved the name without my having gone through the channels, though eventually it did make me fill out the official form.

No harm done, and it seemed to me that nobody cared much. At least, that’s what I thought.

Unknown to me there was a group who cared a lot. Somewhere in the far corner of the Internet was a chat group composed of astronomy enthusiasts who had appointed themselves the celestial police. I didn’t know they existed until one day a student of mine pointed me to their chat site with the comment “Wow, they really hate you, don’t they?” And it did seem as if they hated me, or at least felt that antagonistic indignation that can be pulled off particularly well on the Internet.

They were angry because with Sedna, I had not only broken the rules, I had done so on purpose. At the time of the announcement of Sedna’s existence, we didn’t quite have enough data for Sedna to officially qualify for a name—it would take us another few months to have what we needed. The rules on when an object qualifies for a name are obscure, uninteresting, and designed to keep names from being given to insignificant asteroids that are seen a few times, then never again. Nonetheless, they are the rules, and to the zealous enthusiasts, they must be followed at all cost to prevent astronomical chaos from breaking out.

I admit that in the week before the announcement, even I worried a bit about breaking the rules. I am, by nature, a rule follower. But I really wanted Dutch to be Sedna in time for the announcement. I thought it mattered—and, it turned out, based on those crayon drawings, it did. Finally I decided I would buck the rules, though politely. I called Brian Marsden, an astronomer at Harvard University who was, in my opinion, the gatekeeper of the solar system. He was the person to whom you sent the very first announcements of discoveries. He checked that your calculations were right. He put your discovery on the official list. And he was always the first to be amazed and say, “Wow!What a great discovery.” Brian was also the secretary of the Committee on Small Body Nomenclature. I told him what I was planning to do. He asked if he could tell the chair of the committee ahead of time. Of course, I said. Everyone agreed that a name was a good thing and that Sedna was a good name.

To the chat group, though, I was a rule breaker in need of punishment. One particularly agitated enthusiast tried very hard to prevent me from officially naming Sedna Sedna. Before Sedna was quite eligible for an official name, he proposed, through the official channels, that an unremarkable, hitherto anonymous asteroid—which was nonetheless eligible for a name—be named Sedna, after the Inuit goddess of the sea. No two things in the solar system can have the same name, so my Sedna would have had to get a different name.

“Rejected,” declared Brian Marsden. Names of important mythological figures would be used only for important astronomical objects.

The enthusiast next proposed to name the unremarkable asteroid after Kathy Sedna, a Canadian singer.

“Clever,” responded Brian Marsden, who, being in charge also of when things are eligible for names, quickly realized that my Sedna was now eligible and made sure the name became official.

I found all of this pretty amusing at the time. It was proof to me that names do, in fact, matter, and I even found it moving that there were people who cared so much about the details of scientific naming. I didn’t know that in just eighteen months some of these very people would have a hand in almost stealing the most important discovery I had ever made.

Sedna remained Sedna. And with all of the crayon drawings showing Sedna’s rightful place in the solar system, Sedna was surely a planet, right? It’s true that I had argued against Quaoar and Pluto being planets on the basis of their being in the middle of swarms of similar objects. To me, it made no sense to pull one or even a few objects out of the swarm and call them something other than part of the swarm. But Sedna was, as far as we knew, all by itself. There was no swarm of objects out in the region of space where nothing was supposed to be found. Couldn’t it be called a planet? That, too, made no sense. Sedna would eventually be found to be part of a swarm, too. If we called Sedna a planet now, when that swarm was finally found, we would have to go through the process of planetary argument all over again. It seemed better to put Sedna in the right place to begin with.

Besides, Sedna was smaller than Pluto. In the beginning, we had been certain that Sedna would be bigger than Pluto. It was so bright! But when we finally got a chance to look at it with the Hubble Space Telescope, thinking we would get to see a little disk of a planet, all we saw was a tiny point of light, and that tiny point of light told us that Sedna was no more than about three-quarters the size of Pluto. How could that be? The answer is always the same: albedo. Sedna has an even more reflective surface than Quaoar, so part of the reason it is so bright is simply that reflectivity. Still, three-quarters the size of Pluto is big! No one else alive had ever found anything bigger in the solar system. But finding bright things that are almost certainly bigger than Pluto only to realize that, well, no, they aren’t actually bigger after all, gets old.

I hadn’t thought about it for a while, but it had been four years since my bet that someone would find something bright enough to be called a planet within five years. Much had happened since that bet. We had found Quaoar, at half the size of Pluto; Sedna out where the solar system was supposed to end; and dozens of other smaller objects that were nonetheless among the biggest things anyone else had ever seen. But we hadn’t found anything yet that would qualify for the bet to be won.

We announced the discovery of Sedna in February 2004. My bet ended on December 31. I had a little more than ten months to find something truly large, or I was going to lose.

I hate to lose.

And even worse than losing, I hate being stupid.

One thing nagged at me. I had almost missed Sedna. Sedna is so far away and therefore moves so slowly that the computer program I had written had almost ignored it. If Sedna had been just a little farther away and therefore moving just a little more slowly, we would never have found it. My computer program would have declared it to be a stationary star and kept searching. If Sedna was there and had been almost ignored, couldn’t there be something far out there that had been ignored? Finding such distant things would be crucial for testing my hypothesis about the birth of the sun and the odd population of distant objects that would have been created. But also, if we can see things that far away, they have to be big. It occurred to me that one of the best places to look for planets might not be in the remaining unexplored parts of the sky but in the many, many pictures I had already taken. If there was a planet already there that I had missed the first time around, I would, indeed, feel I had been stupid. But as I had learned earlier, the trick was not to figure out how not to be stupid, the trick was to be smart instead.

I spent most of that summer in my office slouched in front of my computer screen, writing, testing, and rewriting software. About halfway through the summer, one of the other professors on my hallway started commenting.

“You never move,” he said.

“My fingers move.”

In fact, my fingers moved a lot. I had thoroughly rewritten all of the computer software. Chad had written the first version without the benefit of having any of the data at the time. With the luxury of data, I could rewrite it to work better, run faster, search farther, and see fainter objects. I was ready. I started spending my days not just looking at the new pictures coming from the telescope the night before but also scanning the thousands of pictures that I had stored on the disk drives of my computer.

Someone watching over my shoulder that summer would have seen an incredibly monotonous sight: Mike presses a button; a new series of images begins blinking on his screen; he stares for three seconds; he presses a button marked “no”; new images appear.

I did this for hours a day. My posture got even worse. My back ached. But I was discovering things in the old pictures. The first time around, we had missed a lot. This time, I didn’t want to miss anything.

I think of this period in the fall of 2004 as one of the most fertile in my life. Still, though, there were no planets, and I was losing my bet. I was working longer hours, sleeping less, all in the hope of getting through all of the data before the end of the year. I really did not want to lose the bet. If there was something to be found in the old pictures, there was nothing, absolutely nothing, that would stop me from finding it. Well, almost nothing.

At the beginning of December, taking a rare break from looking at my old pictures, someone else showed me a picture of something I had never seen before. The moment I saw it, my mind flashed back to images I remembered having seen in high school. In 1982, a Russian Venera spacecraft sent back the first—and still only—color pictures from the surface of Venus. Venus is a tough place to take pictures from. The surface has an atmospheric pressure ninety times higher than the earth’s and a temperature of more than eight hundred degrees, which would melt the lens of any camera. The Russians therefore built the camera inside a giant can to keep the extreme pressures and heat out as long as they could. To see Venus, a periscope popped out of the can and scanned around. Even so, the whole contraption lasted only two hours before it died.

The pictures that the Russians sent back from Venus have a peculiar characteristic to them. Because of the periscope, they are oddly distorted, as if they had been taken by a fish-eye lens. Because of the thick clouds of sulfuric acid that cover Venus, among other things, the color pictures have an oddish orange glow and appear almost to be black and white. They are hard to mistake for almost anything else.

I had been spending most of my time those past few months staring at a huge computer screen hoping to be the first person ever to see a new big thing moving through the distant regions of space. That morning, I stared at a smaller screen and examined a black-and-white image with an orange tint to it and an oddly distorted view like that through a fish-eye lens. It wasn’t Venus. In the middle of the oddly distorted view was a little bean-sized object. Looking at the sonogram, Diane and I, along with our doctor, were the first people to see the tiny movements of a little heart beating.

“Hey!” I said. “It looks like the Venera lander pictures of the surface of Venus.”

“You’re insane,” Diane said.

We told our families on New Year’s Eve. Mine were visiting from Alabama. Diane’s lived in town. Everyone sat down to dinner.

I began: “Before dinner, I’d like to make an announcement.”

I had been saying this at every family dinner since Diane and I had been married. I usually then proceeded to say, “It’s time to eat.” People who are regulars at our dinners barely look up while awaiting the now-tedious punch line.

My family, however, had never heard the joke. They gasped slightly. Diane’s father quickly interjected, “He says this every time, just ignore him.”

Everyone calmed down and ignored me, until I said, “We’re expecting a baby girl in July. Her real name will come later, but her current code name is Petunia.”

That night, as the clock struck twelve, my five-year bet came to an end. I lost the bet, but I didn’t feel so bad. Instead of seeing the end of the solar system, I saw that everything was just beginning.