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


When I first started looking for planets, I lived in a little cabin in the mountains above Pasadena. I have a feeling I was the only professor at Caltech at the time who lacked indoor plumbing and instead used an outhouse on a daily (and nightly) basis. I worked long hours, and it was almost always dark, often past midnight, when I made my way back into the mountains to go home for the night. To get to my cabin, I had to drive up the windy mountain road into the forest, past the national forest parking lot, and down to the end of a dirt road, and finally walk along a poorly maintained trail by the side of a seasonal creek. For some time after I first moved in, I tried to remember to bring a flashlight with me to light my way, but more often than not I forgot. On those nights, I had to navigate the trail by whatever light was available or, sometimes, by no light whatsoever.

The time it took to get from the top of the trail to the bottom, where my cabin was, depended almost entirely on the phase of the moon. When the moon was full, it felt almost like walking in daylight, and I practically skipped down the trail. The darker quarter moon slowed me a bit, but my mind seemed to be able to reconstruct my surroundings from the few glints and outlines that the weak moonlight revealed. I could almost walk the trail with my eyes closed. I had memorized the positions of nearly all the rocks that stuck up and all the trees and branches that hung down. I knew where to avoid the right side of the trail so that I wouldn’t brush against the poison oak bush. I knew where to hug the left side of the trail so that I wouldn’t fall off the twenty-foot embankment called “refrigerator hill,” named after a legendary incident when some previous inhabitants of the same cabin had hauled a refrigerator most of the way down the trail before losing it over the edge and into the creek at that very spot.

I had almost memorized the trail, but every twenty-nine days I was reminded that there is quite a big difference between memorization and near memorization.

Every twenty-nine days the moon became new and entirely disappeared from the sky, and I was almost lost. If by luck there were clouds that night, I might be able to get enough illumination from the reflected lights of Los Angeles, just a few miles away, to help me on my way. But on days with no moon and no clouds and only the stars and planets to light the way, I would shuffle slowly down the trail knowing that over here—somewhere—was a rock that stuck out—there!—and over here I had to reach out to feel a branch—here! It was a good thing that my skin does not react strongly to the touch of poison oak.

These days I live in a more normal suburban setting and drive my car right up to my house. I even have indoor plumbing. The moon has almost no direct effect on my day-to-day life, but still, I consciously track its phases and its location in the sky and try to show my daughter every month when it comes around full. All of this, though, is just because I like the moon and find its motions and shapes fascinating. If I get busy, I can go for weeks without really noticing where it is in the sky. Back when I lived in the cabin, though, the moon mattered, and I couldn’t help but feel its monthly absences and the dark skies and my own slow shuffling down the trail.

Contrary to the way it might sound, however, back then the moon was not my friend. The two-and-a-half-year-old daughter of one of my best friends—a girl who would, a few years later, be the flower girl at my wedding—would say, when asked about the bright object nearly full in the night sky: “That’s the moon. The moon is Mike’s nemesis.” And indeed, the moon was my nemesis, because I was looking for planets. Astronomers build telescopes in the most remote places they can find—the mountains of Chile, volcanoes in Hawaii, the plains of Antarctica, even in outer space—partially in the hope of escaping the city glare that increasingly permeates the skies. For all that effort, though, we can’t hide from the brightest light that illuminates the night skies and washes out the faintest stars: the full moon.

As a new graduate student in astronomy at Berkeley, I had never previously considered the moon to be an obstacle. It was still the world that people had walked on early in my childhood, the scene that I’d drawn picture books of, the thing I’d tried to reproduce in my muddy, rock-splattered backyard; it was not a menace to be avoided. But I soon learned the lingo: Nights when the moon was full or nearly full were called “bright time” and were to be avoided by serious astronomers looking for faint objects in the sky. Times when the quarter moon was out for half of the night were “gray time.” But the coveted nights were those when the moon was new and didn’t disturb the dark sky at all. Only on those nights—“dark time”—do astronomers have a hope of detecting the very faintest blips of light that their telescopes can possibly see. I was now looking for planets, and a distant planet would indeed be a faint blip of light that the full moon would thoroughly overwhelm. So the moon became my nemesis.

I had started looking for planets by accident. In 1997 I began working as an assistant professor at Caltech, and I realized that I didn’t really know what I was doing. Caltech is one of the best places in the world to be an astronomer. The university owns an inordinate number of the largest and best telescopes in the world, so Caltech astronomers are always expected to be—and often are—the leaders in their fields. When I started at Caltech, at the age of thirty-two, I suddenly had access to all of these premier telescopes, and I was told, essentially: Go forth! Use these telescopes to lead your field to new great things!

I had spent most of the six years of my Ph.D. studying Jupiter and its volcanic moon, but it was time to start something new, and here was my chance. Go forth! I thought. Okay. But where? Sure, I knew how to use the telescopes and the instruments and how to point them at the region of the sky in which I was interested, and I knew how to collect and analyze the data. But figuring out where to point the telescopes in the first place and why you’re doing it is much harder. I was thoroughly overwhelmed. But I would not last long as an assistant professor if I didn’t discover something big soon. I took out the list of all of the telescopes with all their capabilities and thought and stared.

It had been five years since that afternoon when Jane Luu had first told me about the Kuiper belt, and by this point almost a hundred small bodies were known in distant orbits beyond Neptune. It was becoming increasingly clear that the study of these very distant, very faint objects was going to be a major new field in astronomy. Big telescopes are particularly good for studying very distant, very faint objects, and I suddenly had big telescopes at my disposal. Go forth! I thought.

I didn’t quite boldly go forth; instead I took a tiny step. I set out to test one of the hypotheses that was floating around in the scientific community at that time: that the objects in the Kuiper belt have mottled surfaces owing to the effects of craters formed by giant impacts, just like those that I could see on the moon. Proving or disproving this hypothesis would not be considered by anyone to be a major scientific advancement, but it was a start, and I needed a start. To test the hypothesis, I was going to spend three nights at the 200-inch Hale Telescope carefully studying a few objects out in the Kuiper belt to see if their surfaces were indeed mottled. The three nights I was scheduled to be at the telescope happened to fall over Thanksgiving, a fate that often befalls the youngest astronomer on the block. But the three nights were dark time. There would be no moon to disturb my view.

A day before Thanksgiving, I took the three-hour drive south from Pasadena, across the farmland (now housing developments) of the Chino Hills, through the dusty Pala reservation (now a multistory casino), and into the forested road (now a road through burned stumps) leading to Mount Palomar. The drive gives ample opportunity to stare at the sky and fret about occasional clouds and potential bad weather. This day there were no occasional clouds or potential bad weather: There was total cloud cover and continuous bad weather. The forecast was bleak. Astronomy is not always about bad weather at telescopes, but when you are young and eager for discovery or even just a few small steps, the nights of bad weather are the ones that seem to stick most in the mind.

The fog settled in thickly around the mountain as I arrived at the top and drove to the ornate old two-story heavy stucco dining and sleeping area known as the Monastery (which was an appropriate image for the earlier days of astronomy, when women were not allowed to stay). I went to the telescope to set up the instruments for the night of work; I spent hours in the windowless dome testing and calibrating and double-checking all of the settings I was going to use. As I finally stepped outside to walk to dinner, a light snow began to fall. After dinner the snow stopped, but a dense fog remained for the night. I stayed awake the whole time, hoping that somehow the fog would lift and I could start working. But it never did. I finally left the telescope to head back to the Monastery as the sun was rising and turning the fog from thick and black to thick and vaguely gray. At the Monastery, I closed the blackout curtains in my tiny room and slept until 2:00 p.m.

Opening the blackout curtains, I was greeted with more fog and now a heavy covering of wet snow. I was informed that the snow meant that there was no chance the telescope would be working that night; the dome enclosing it was frozen shut and would require direct sunlight to get unstuck. The snow also meant that the roads up and down the mountain were impassable in my two-wheel-drive truck. Instead of a quick meal before sunset with the other astronomers so that we could all run to our different telescopes when darkness arrived, we were all stuck at the Monastery for Thanksgiving. There was no television and no Internet connection, so after dinner, the other astronomers and I built a fire and caught up on our scientific reading. I was still scouring everything I could find to help me come up with ideas of what I might do. Every time I had a thought, I would ask the others around the fireplace questions about the local telescopes and how I could use them to help with this problem or that.

“How well does the infrared camera at the Hale Telescope work?” Very well, was the answer. A general conversation would follow. We would all drift back to our reading.

“Is there a long-slit mode for the echelle spectrograph?” I would pipe out. No, was the answer, but we all speculated about how a quick modification would make one possible.

“Does anyone know anything about the new thermal imager that is coming next year?” Yes, indeed.

During the course of the evening, I covered, I thought, every combination of telescope and camera and spectrograph and instrument that was available at Palomar.

Eventually one of the other astronomers asked: “Have you ever thought about the 48-inch Schmidt Telescope?”

No. I hadn’t. In fact, I only vaguely knew where it was. Down one of those side roads I never drove down? That little dome over by the water tower, maybe?

I did know, though, that when astronomers were building the huge 200-inch Hale Telescope more than fifty years ago, they realized that having the biggest telescope in the world didn’t do you much good if you didn’t know where to point it (a dilemma with which I am quite familiar). They decided that they needed to make a detailed atlas of the entire sky—a road map for the big telescope. So they built a smaller telescope, then known simply as the 48-inch Schmidt (after the size of the mirror and the general type of telescope), just down the road. The 48-inch Schmidt took pictures of the sky night after night until finally—for the first time in history—every patch had been photographed. The resulting maps of the skies—the Palomar Observatory Sky Survey—are famous throughout the astronomical world. At one time, all astronomy libraries had a wall full of cabinets containing fourteen-inch-square prints that together made up the complete Palomar Observatory Sky Survey. Each print, when pulled out of its special protective envelope, shows an area of the sky that looks about as big as your fully outstretched hand held at arm’s length. It takes 1,200 of those prints to cover the whole sky, from Polaris, the North Star, all the way down to the Southern Cross.

As a graduate student, I had been instructed in the arcane mysteries of the correct use of the Palomar Observatory Sky Survey, which was simply called POSS by the cognoscenti. First, you go to the astronomy library and open the big cabinets; then, based on the sky coordinates of where you want to be looking, either you find the library ladder and climb to the top (if you’re looking in the far north), or you sit on the floor (for the farthest southern objects), or, if you are fortunate enough to be looking for something directly overhead, you can stand comfortably and look straight ahead. With luck, you will find that the prints are stacked in the order they are supposed to be in, from pictures of the sky farthest to the east to pictures of the sky farthest west. If you’re unlucky, the one picture you’re looking for will be the only one out of place, and your search might take an hour. When you find the picture you want, you pull it out, set it on the large library table, put your face down close to the picture to see the millions and millions of stars and galaxies, and use the jeweler’s loupe to find the precise area of the sky you’re looking for. Finally, you pull out a custom-built Polaroid camera from its case, point it at the spot you’ve identified, and take an instant picture of a postcard-sized section of the sky survey print. That Polaroid print is now your personal road map.

For decades, astronomers carried these Polaroids with them to telescopes all around the world. When you commanded your large telescope to point to the spot in space in which you were interested and you looked at the TV screen, you were usually greeted by a fairly unremarkable field of stars. The Polaroid pictures were the only way to know that the unremarkable field you were looking at was the one in which you could find the galaxy or the nebula or the neutron star you were looking for. In the control room of any telescope at any night of the year, you could find an astronomer or a group of astronomers holding a Polaroid print and staring at the TV screen. Often the actual image of the sky from the telescope was flipped or upside down and no one could ever remember which particular way this combination of instrument and telescope flipped images, so there would always be a time in the night when three or four astronomers would be squinting at a little screen full of stars, holding a little Polaroid picture full of stars, and turning the picture sideways and upside down until someone exclaimed, “Ah ha! This star is here, and that little triangle of stars is here and we’re in just the right place.” These days the technique is mostly simpler—the Palomar Observatory Sky Survey pictures are all quickly available over the Internet, and the cabinets full of prints are gathering dust; but because you can’t take the computer screen and turn it sideways or flip it over, the little group of three or four astronomers is now more often than not standing with their heads cocked in all possible combinations of directions until the lucky one exclaims, “Ah ha!” and then all heads immediately tilt to that direction.

Though the 48-inch Palomar Schmidt was famous to astronomers the world over, I had not even considered it worthy of thought, for one good reason: The telescope still used relatively primitive photographic technology to take pictures. Astronomers a generation before me all learned photographic astronomy: how to load film in the dark, how to ride in a tiny cage suspended at the top of the telescope, how to carefully move the telescope through the sky, how to develop and print. My generation was the first entirely digital generation of astronomers. All telescopes today have digital cameras that use, in only slightly fancier form, the same technology used in everyone’s handheld digital cameras around the world. The change in astronomy is as dramatic as it has been in photography. The ease and speed with which images can be obtained and examined and manipulated and shared has transformed the way that astronomy is done today. So when I overlooked the 48-inch Schmidt Telescope, it was mostly because I considered it a relic from the days of prehistoric astronomy.

But on that snowy, foggy Thanksgiving night at Palomar, I decided that visiting this relic to see how ancient astronomy used to be performed would be an entertaining way to spend a few of the nighttime hours. After making sure I knew exactly which way to go, I walked down the dark, snowy road through the piney woods, past the largest telescope, down a road I had never taken, to where the 48-inch Schmidt resided. Someone was inside, tidying up in the cramped control room that sat underneath the telescope. I introduced myself and met Jean Mueller. She was tidying, in lieu of her usual nighttime job, which was to use the 48-inch Schmidt to once again make a new map of the full sky to compare to the first.

Using the 48-inch Schmidt? It was a fossil. Why would anyone still want to use it and its messy and cumbersome photographic plates? The answer is relatively simple. Even though astronomy has progressed greatly since the days of photographic plates, and even though digital cameras make astronomers’ lives incomparably easier and better, one thing had gotten worse. A Schmidt telescope is designed to look at a huge swath of sky at once. Every time a fourteen-inch-square photographic plate—literally just a piece of glass with photographic emulsion painted on one side of it—is placed at the back of the telescope and exposed to the night sky, an enormous piece of the sky is photographed. Digital cameras on telescopes, in contrast, are much better at seeing faint detail but much worse at seeing large swaths of sky. A typical telescope equipped with a digital camera could, at the time, only see an area of the sky more than one thousand times smaller. The obvious solution would simply be to build a bigger digital camera, but to see as much sky as you could see with the photographic plate you would need a five-hundred-megapixel digital camera. Even today that is a daunting number. At the time, when only high-end photographers had a single megapixel to their name, if you wanted to make a map of the sky, just as the 48-inch Schmidt had done in the 1950s, it made much more sense to accept the hardships of the photographic plate for its unparalleled ability to sweep up the night sky at a fast pace.

Jean explained this latest survey and described how the photographic plates were taken and developed. She talked about how she had come to be working there at Palomar after a few years at another observatory. She then wistfully told me that the days of the 48-inch Schmidt were almost over. This second Palomar Observatory Sky Survey was almost complete, and she didn’t anticipate that anyone else would be using the telescope and its photographic plates after that. All of the fall sky had already been photographed, and no one planned on using the telescope at all during the fall season the following year.

All major telescopes around the world are scheduled to be used every single night of the year, with the occasional exception being Christmas, though I’ve worked at telescopes on Christmas Day plenty of times myself. I find the idea of a telescope not being used almost viscerally painful. It’s bad enough when the reason is technical or simply weather related, but when a telescope is not being used for simple lack of interest it feels worse. Yes, the photographic technology was old and clunky, but clearly the 48-inch Schmidt was one of the best telescopes in the world, at least for imaging wide areas of the sky.

Wide areas of the sky! This was just what I needed! The study of the Kuiper belt, still in its youth, was hampered by the fact that astronomers had been searching for objects in the Kuiper belt with digital cameras that covered only small areas of the sky at once. They were successfully finding objects, but the objects were all small and faint. Imagine being interested in exploring the inhabitants of the ocean but all you have is a small handheld net. If you dip your net in the sea many times, you will certainly find a vast collection of microbes and krill, but you will never know that there are dolphins and sharks and even the occasional whale. In contrast, the photographic plates from the 48-inch Schmidt were not nearly as sensitive as the digital cameras that other astronomers had used—the net was so large that the krill and the microbes would fall right through—but we had a net big enough that we could cover the whole ocean. The big fish would have nowhere to hide.

I thought about the biggest fish.

I had already been thinking by this time that Pluto might not be a solitary planet out there in the Kuiper belt; there might be others still to be found. And using the Schmidt was clearly the way to find them. There was a major problem, though. The last time I had touched real film was when I was in third grade and my father and I had built a little darkroom and developed our pictures from the pinhole cameras we made. There was no way I could carry off this project. I gingerly inquired as to what Jean was doing next fall, when the telescope was to be idle. She didn’t know. She and her coworker would presumably be assigned other tasks around the observatory during that nonworking season. And what if someone else was interested in using the telescope? I asked. Her face lit up as she quickly exclaimed, “I’m sure everyone would be thrilled—we would love to have new projects on the telescope.”

Then she asked: “Do you think we might find a planet?”

•   •   •

And so I came to be looking for planets. A year later I got to know Jean and her coworker Kevin Rykoski extremely well, as every night, except for bright time, when my nemesis interfered, I called in to talk about what section of the sky to photograph that night. Every night, in all possible permutations, we discussed the position and phase of the moon, the possibility of clouds or fog, and the success or failure of the pictures from the night before. Everywhere I went I carried my hardbound notebook containing maps and calendars and records of everything that we had done to date. Every night, no matter what time zone I was in or continent I was on, I called in to the 48-inch Schmidt precisely thirty minutes before the sun set (the time of which was recorded for every night in my black notebook). I remember making the call from a pay phone on a busy evening street in Berkeley, early in the morning from a hotel in northern Italy, well past dark from my mother’s house in Alabama, but most of all from that little cabin in the woods.

I had meticulously worked out the procedure. Every month we would cover fifteen separate fields, or an area that covered a little over 1 percent of the full sky. While that doesn’t sound like much, in just a single month we were going to have covered more sky than all other astronomers searching for Kuiper belt objects had covered in the preceding five years. On a typical night, we would try to cover three or four fields. To do so, Kevin or Jean would walk from the dimly lit control room crammed with computer equipment and go up a winding set of stairs to the floor of the telescope dome. Once inside, all of the lights would be put out as they would unpack one of the photographic plates from where it had been stored in a light-tight box. From my pinhole camera days I remembered that film was developed in red light, which doesn’t affect it. But these photographic plates were designed to be especiallysensitive to red light, as objects in the Kuiper belt tend to be on the red side. All of the work on the plates, then, had to be done with no lights whatsoever. When the plate was unpacked, it would be walked to the telescope and inserted into the base. Only then was the shutter of the telescope opened and the light from the sky allowed to beam onto the plate. Thirty minutes later, someone would again walk to the top of the stairs in the dark, take the plate out of its holder, and then walk to the other side of the dark dome floor and place the plate into a miniature manual elevator and drop it down to the other person who was waiting in the darkroom below. The person on the dome floor would get a new plate and begin looking at a new patch of sky, while the person in the darkroom washed the plate in a succession of developer and fixer fluids until, about the time that the plate was finished, a new plate would appear in the miniature elevator. In the morning, before going to sleep, Jean and Kevin would look at the crop of pictures from the night. Some would be smeared or have defective photographic emulsion and have to be rejected, but the good ones got labeled, put into the cabinet, and filed on my list. The next night we would review what had happened the night before, discuss the weather forecast, curse the encroaching moon, and start over again.

I found this exhausting, and I was the only one of the three of us actually sleeping at night.

The goal was to get three good images of each of the fifteen fields during the course of the month. Ideally they would be taken three nights in a row. My job was to examine each of the images and, as astronomers had been doing for two hundred years, look for the things that move.

Kevin and Jean must have been happy that the moon existed, since bright time was the only time that they got a few days off. But I was no fan of the moon. I became increasingly agitated as the month progressed from gray to dark to gray again and finally the bright approached. Invariably as the month was coming to an end we would be behind schedule owing to problems with the weather or problems with the photographic plates. I would count ahead the number of nights left before bright time commenced and almost always find that everything had to go perfectly or we would lose one of our fields. And every lost field meant that any planets out there in the sky suddenly had a huge place to hide. Our net would have holes. Near the end of the month, Jean and Kevin would invariably work overtime. I could do nothing except sit in Pasadena, stare at the moon, and fret.

Somehow, we managed. In two years of surveying the sky with the 48-inch Schmidt Telescope, we actually managed to get every image of every field we wanted except for one. We mostly beat the moon. Final score: 48-inch Schmidt, 239 fields; moon, only one field. Those 239 fields we had covered were only about 15 percent of the whole sky, but it was, we thought at the time, the right 15 percent. The moon and planets are all strewn across the sky in a giant ring encircling the sun, and we had looked at that ring—as well as a good bit above and below—for a period of about four months, or one-third of the whole ring. So while we had looked at a relatively small fraction of the sky, it was much of the interesting sky, and it was enormous compared to what had been previously examined. We hadn’t taken our net through the entire ocean, but thought we knew one of the whales’ major swimming grounds, and we had trawled it all.

Looking at vastly more sky than anyone else had ever looked at for large objects out in the Kuiper belt was so immensely exciting that I could hardly contain myself. I knew that there would be big discoveries, and having new pictures come in night after night after night with only a break for the full moon kept everything at a constant peak. I talked to my friends about new planets. I thought about names for new planets. I gave lectures about the possibility of new planets. I did everything I could, except find new planets.

Of course, I did more than talk on the phone and make sure that the pictures got taken. After each set of pictures was exposed, the photographic plates would be put into large wooden crates and shipped from the mountaintop down to my office in Pasadena, where my work would begin. I needed to turn those crates full of plates into discoveries of planets.

Seventy years earlier, Clyde Tombaugh found Pluto by doing almost exactly the same thing that I was currently doing, except that he did all of the work himself. He would stay up all night exposing the photographic plates to the sky, and then in the daytime he would look for things that moved. To look, he would take a pair of photographic plates that showed the same region of the sky and then load them into a specially constructed apparatus the size of a large suitcase, called a “blink comparator.” Inside the blink comparator, a light would shine through one of the plates and project an image toward the top, as if the photographic plate were a giant slide. On the outside, Tombaugh could look into the comparator with an eyepiece and have one of the slides projected into his view. The special part, though, was a little mirror inside that could quickly flip back and forth so that Tombaugh could look at one of the photographic plates and then the other in as quick a succession as he wished. All of the stars in the sky, all of the galaxies, all of the nebulae, would appear the same on each of the two plates, but anything that moved or changed or suddenly appeared would jump out as the two photographs were blinked.

Palomar Observatory had had a similar apparatus to Tombaugh’s in its early years, but it had been disassembled a couple of decades earlier. But even if such a thing did still exist, it would have done me no good. Because the telescope that I was using was so much more powerful than the one Tombaugh had used to find Pluto, each of my images showed one hundred times more stars, and thus would have taken one hundred times longer to have gone over by eye. Early on in the project, I calculated that to look at every star on every photographic plate by eye would have taken me forty straight years of staring into the blink comparator and slowly watching pictures of the sky go by.

Not wanting to wait forty years, and it being 1998 instead of 1930, I put the computers to work instead. First, we needed to scan the photographic plates to get them into digital form, and then the computer could do the rest. The scanning was quickly done on a big machine that already existed. Getting the computer to do the rest, though, took longer. There is no software package that looks for planets. I would have to write it myself. Though I knew nothing about emulsion and developer and fixer, this I could do. This I was good at. I had been writing little computer programs to analyze and predict and follow the stars and moons and planets in the night sky since high school. This would be the first program that actually mattered.

I spent most of that year slouched in front of a computer screen in my office, testing, scowling, starting over, typing furiously, and pondering. For someone looking for planets, I spent an awful lot of my time looking at computer code and numeric outputs instead. My nights were spent not outside staring at the sky but inside staring at numbers and computer programs and doing every test conceivable. I needed to make sure the software wasn’t going to make any mistakes. I wanted to make sure that I didn’t do anything stupid that made me miss planets that were right in front of me.

I made the computer begin by looking at a triplet of scanned photographic plates. It examined each of the little blips of light on each of the three images taken over the three nights. All of the stars in the sky, all of the galaxies, all of the nebulae, had the same coordinates on each of the three photographic plates, so the computer quickly identified them as not moving and tossed them aside. Sometimes, though, something appeared at a spot in one image where the other two images showed only blank sky. The computer took note. It could be many things. Sometimes stars in the sky get brighter and suddenly show up where they weren’t seen before. Sometimes satellites in orbit around the earth give a sudden glint that looks like a star. Sometimes dust blowing around at night sifts through the open shutter of the telescope and settles down on the photographic plate, disturbing the precarious emulsion and making something that looks vaguely like a star. But sometimes something appears where it has never appeared before because it is slowly wandering across the sky and that single picture happened to catch it momentarily in one spot. In that case, an image the next night would find it again, only a little displaced from the previous night. I used the third picture as a final check. When the computer found a third object that looked as though it could be connected to the first two, it put that object on a list of potential new wanderers and moved on to the next spot in the sky. All of this takes, of course, about a millisecond. To process our two years’ worth of images took under two hours.

So after Kevin and Jean had spent all of those nights loading and developing plates, and I had spent a year programming the computer, and the computer had spent two hours processing all of the final data, I finally had a list of all of the potential new planets to look at. I had been sustained throughout this time by the thought of this moment. I was going to find a planet, and the solar system would never again be the same. When I first opened up the list on the computer screen and started scrolling down, I must have gasped. The list was 8,761 candidates long.

I knew that the computer would be overzealous in identifying potential planets; in fact, I had written the program to make sure that the computer was overzealous. I had decided early on that I would make the computer find everything even remotely possible, and I would look at each thing the computer picked out by eye to double-check it. But 8,761 objects to check by eye was going to take a long time.

I slowly began to go through the list. I would press a button on my computer, and on my screen three pictures would appear of the three nights of the same small region of the sky, with little arrows showing where the potential planet lay. I saw an amazing number of small glitches that had fooled the computer. Scratches on the photographic plates, of which there were many, would cause a star to disappear one night and so appear as if it were new the next. Anyone looking at the pictures could see that it was just a scratch, but to the computer it appeared as dark sky. Sometimes the light from a particularly bright star would get reflected around in the telescope perhaps dozens of times and give tiny apparent glints all across the sky. By eye, you would notice all of the glints and you’d see the proximity of the bright star, and you would quickly say, “Ah, that’s just a bright star making glints,” but to the computer it was a star never seen before.

The examination took months. On the computer screen, I had a “no,” a “maybe,” and a “YES!” button that I chose from after examining each of the pictures. Had it been a mechanical button instead of a virtual one on the computer screen, I would have worn the “no” button through. The “maybe” button got a little bit of action, too. Sometimes I would look at three pictures and find no obvious problems with what the computer had done, but I still wasn’t entirely convinced that what the computer had picked out was really there at all. The photographic emulsion was sometimes a little uneven, and the computer might have picked out a slightly brighter spot that really was just the sky. A tiny speck might appear that was possibly a faint star, but I was not quite convinced. In all of those not-entirely-sure cases, I would simply press “maybe.”

“YES!” was reserved for the no-questions-no-problems-definitely-really-there-moving-through-the-sky cases. Every day I would come in thinking that perhaps today was the day that I would finally push the “YES!” button. Every day I would spend hours staring at the computer screen, pushing “no,” and occasionally, very occasionally, “maybe.” But the “YES!” button remained untested. After going through the entire set of potential planets that the computer had picked out, I never once used the “YES!” Final score: “no,” 8,734; “maybe,” 27; “YES!” 0.

It was hard not to feel distressed. What if there really were no other planets out there? What if three years of photographing and computing and blinking came down to nothing at all? What if the big project designed to make my splash as a young professor at Caltech disappeared without a ripple? I had been telling everyone for three years now that I was looking for planets, that I was going to find planets. What if there were no planets?

I still had hope, though, in the twenty-seven maybes. I spent much of the fall of 2001 at Palomar Observatory trying to track them down. For a few dark nights every month, I would drive to the mountaintop, arriving early in the day to plan for the night and prepare the telescope, eating dinner before the sun was close to setting, packing up a bag full of truly awful snacks designed to keep me awake throughout the night, and then heading for the control room of the 60-inch telescope.

This telescope had a modern digital camera, which meant that it was quite sensitive but that it covered a tiny area of sky. The nights were carefully choreographed so that I could spend the most time looking at the expected locations of the twenty-seven maybes. Because a full year had passed, they had moved quite a ways, and it was impossible to know precisely where they might be, so I would spend hours scouring large parts of the sky, taking a picture, and coming back to the same spot an hour later and taking another picture. I didn’t even bother writing a computer program for these; I would just look at the blinking images on my computer screen the second that they came down from the computer. All night, every night there, I would take a picture, move the telescope over, immediately start another picture, stare at the last picture while taking the current picture, and continue on until dawn. Then I would slowly and wearily walk the winding road the half mile back to the Monastery, often startling foxes or bobcats out for a dawn hunt. Around noon, I would wake up, have breakfast, and begin the day again.

During those first few months tracking down maybes, I felt excited when the sun went down.

Tonight is the night! I would think.

As the fall progressed, though, I was slowly becoming dejected.

I spent so much of my time at Palomar Observatory that fall that I didn’t have to think twice when I got a request to give a talk at the observatory to a group associated with Caltech. I was going to be there the night before anyway, so I figured I might as well stay one more night to give the talk. On my calendar I just wrote “talk to some group.” The group was to arrive by bus in the late afternoon, take a tour of the massive Hale Telescope, and eat dinner and hear my talk on the floor of the dome with the telescope perched overhead. It sounded fun. I like giving talks to groups like this.

The afternoon the group was to arrive, I waited on the dark ground floor of the observatory until I heard a knock on the door. As I opened it, I was blinded by the afternoon sun. When my eyes adjusted again, I finally saw the organizer of the tour walk in.

“Hi, I’m Diane Binney,” she said.

She was well dressed, poised, glamorous, outgoing, radiant. She was everything that you don’t stereotypically expect to find in someone from Caltech (including, in particular, me). I quickly introduced myself, and I thought: Who is this person?

Diane Binney was the well-loved director of a group whose members attended tours and special talks and traveled to exotic locations, all associated with Caltech and its research. Diane had arranged this trip to Palomar Observatory and had invited me to speak, and, as I learned much later, everyone except for me on the Caltech campus seemed to know precisely who she was and had known for years. I had perhaps been staring into my computer screen too much to have ever looked up and noticed.

I admit that I did not give the people on the tour the full attention that they deserved. I admit to spending more time telling Diane about the telescope and the dome and astronomy than I did everyone else. But I must have given an all-right tour—at least to her—because at some point while walking on a catwalk high above the ground on the outside of the observatory, she said, “Hey, do you ever use the telescopes in Hawaii?”

I do.

“Would you be interested in coming next spring on a travel program where we take people to the volcanoes and then up to the telescopes? Would you be able to talk about the telescopes and give tours?”

Not checking my calendar, I simply said, “Absolutely.”

Dinner soon began. I spoke for an hour and showed pictures of the sky, pictures of telescopes, and graphs of what was to be found out at the edge of the solar system. But mostly I talked about planets. I told the group that there had to be planets out there and that I was going to find them. Even as I said it, though, all I could think of was that I was halfway through my “maybe” list, and still I had found nothing. I could do the song and the dance and put on the excited face, but it was becoming possible that all of my searching would come to nothing.

When the talk was over, the group got on their bus and left. I walked over to the little cottage where Kevin Rykoski lived. I had talked to Kevin and Jean Mueller on the phone every night discussing where to point the telescope, but now I finally had a chance to go sit on Kevin’s sofa and drink a beer. He had been at my talk earlier and had helped with the tour.

Over time, my conversations with Kevin and Jean every night while taking the photographic plates had progressed from simple efficient talk about the sky and the weather to a more general extended chat. Jean would talk about her plans for a dream house on the river, while Kevin told stories about his teenage daughter or described how he would drive directly to the beach on the last morning before bright time started and sleep all day long. Kevin and Jean had also had inadvertent front-row seats to the demise of my long-term relationship from my days in Berkeley and my subsequent retreat from the cabin in the woods that my girlfriend and I had shared, to the death of my father, to the start and end of a new relationship or two; so, as I sat on Kevin’s sofa for the first time, our conversation naturally steered to the personal.

All Kevin wanted to talk about was Diane Binney and why she kept talking to me. I told Kevin about the Hawaii trip and that we were talking logistics. He thought that sounded like an exciting first date. I insisted that it sounded like work, because that was all it was.

Kevin wouldn’t let up. “Yeah, but she was paying you a lot of attention.”

“She runs trips for people; it’s her job to be nice. I’m sure that all of the guys at Caltech that she has to work with get the wrong impression and make idiots of themselves. I’m not going to do anything stupid.”

Six months later, I was in Hawaii with Diane and twenty or thirty people in her group. The group spent an enjoyable week on the lava, at the telescopes, at the beach, learning about geology and listening to me lecture about astronomy. The last night, when she was done with the trip and could finally relax, the two of us found ourselves down on the beach alone sometime after midnight. I pointed out the Southern Cross, just barely visible at the right time of year from Hawaii, and I showed her the paths of the planets and how she could pick out Saturn just setting into the ocean. I told her what it was really like to use the telescopes, and she talked of her nieces back in California. Saturn sank into the Pacific, and we finally walked back to our rooms. I was quite proud of myself for not having done anything stupid.

When we got back to Caltech the following week, I found myself accidentally walking past Diane’s office a few times a day and accidentally running into her and stopping to talk. Every time I did, she was very nice, and I had to remind myself that, truly, it was her job to be nice and to appear happy to see me and that being stupid was the worst thing to do. On accidentally running into her in the early afternoon one pleasant spring workday, I asked if she needed a cup of coffee. She did. We walked down the street, drank coffee, and talked for three hours. Certainly, it was part of her job to be nice to me and cultivate me as a good resource. But it occurred to me that, even accounting for all of that, there was no reason for her to spend three hours in the middle of an afternoon with me when we both had many other things to do. It suddenly occurred to me that, in fact, I had been stupid all along.

Later that summer, when Diane and I went on another trip together, I did no astronomy lecturing, and she brought no group. Instead, the two of us spent a week in a little cabin on a tiny island north of Vancouver. It was the least stupid thing I had ever done.

Sometime during this period it became clear that all of my searching for planets was going to come to nothing, that all of the maybes were turning into definitely nots. Three years of intensive effort to find a planet was leading to the conclusion that nothing was out there to be found. I don’t actually remember when I finally closed the black hardbound notebook for the last time. I don’t know when I really admitted to myself that there was nothing there. In fact, I don’t remember much at all about planets and searching for them around this period. All of the irritation of the quickly dismissed nos and all of the frustration of the maybes that I had spent nights and nights at the telescope trying to track down suddenly seemed much less interesting than trying to figure out the next trip I would be asking Diane to take with me, to which she would inevitably say “YES!”