How I Killed Pluto and Why It Had It Coming - Mike Brown [43]
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