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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 telescopescan 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 forstudying 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