Books
How I Killed Pluto and Why It Had It Coming
by Mike Brown
Spiegel & Grau (Random House), 2010
288 pages, $25.00
Mike Brown, Caltech’s Rosenberg Professor and professor of planetary astronomy, reopened the question of what it means to be a planet in 2005, when he and his colleagues discovered an object out beyond Pluto that was bigger than Pluto. Since Pluto was a planet, surely their find—unofficially named Xena in a riff on the traditional Planet X and the Roman numeral for 10, as well as a nod to TV’s imagining of Greek mythology—must be a planet too, right?
Despite the ominous title, there is much more to this thoroughly engaging and vastly entertaining blend of science and autobiography than Pluto’s demise.
In a lovely bit of framing, the book begins in Huntsville, Alabama, with Brown—the son of a rocket scientist—as a first-grader who had a poster of the solar system on his bedroom wall, and ends with him sharing the wonderment and beauty of a moon-Jupiter-Venus conjunction in the evening sky with Lilah, his three-year-old daughter.
The chapters between lead off with a brief history of the solar system, focusing on the 19th-century bout of expansion that began in 1801 when Giuseppe Piazzi discovered Ceres wandering between the orbits of Mars and Jupiter. This era ended sometime around 1900, when Ceres, Pallas, Juno, and Vesta quietly joined dozens of their fellows as members of the asteroid belt.
Later, Brown’s retelling of his early days in the field of planet-hunting includes a description of old-school astronomy, in which the first step in any project was locating one’s quarry in the definitive sky atlas: the wall of filing cabinets holding the 1,200 fourteen-by-fourteen-inch photographic prints that make up the Palomar Observatory Sky Survey. Each print covers a roughly fist-sized patch of sky and contains millions of stars and galaxies. “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),” he writes. After a hunt that might take an hour if the picture had been misfiled, you would hunch over a jeweler’s loupe to find your target and take a Polaroid shot of the postcard-sized region surrounding it to use as a reference.
“For decades,” Brown continues, “astronomers carried those Polaroids with them to telescopes all around the world. . . . 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 combination of directions until the lucky one exclaims, ‘Ah ha!’”
After years of fruitless searching, the discoveries began in 2002—bodies provisionally named Object X (now officially Quaoar), the Flying Dutchman (Sedna), and Santa (Haumea), all of which at first potentially appeared to be bigger than Pluto, followed by Xena (Eris), which actually was. Underlying the cliffhanger—whether Xena/Eris would become the first new planet in 80 years, potentially opening the door of this once-exclusive club to perhaps hundreds of other claimants—was a subplot of foreign intrigue: the “discovery” of Santa/Haumea by a Spanish astronomer, José-Luis Ortiz . . . who, we find out, had been able to download Brown’s unpublished coordinates from the telescope’s pointing logs. (Ortiz, ironically, had earlier been a postdoc at JPL, leaving just before Brown arrived at Caltech as an assistant professor—one wonders what might have happened had the two become colleagues back then.)
The International Astronomical Union (IAU) settled Xena’s hash relatively quickly by chucking Pluto of out of the planetary club at the August 2005 meeting; resolving the question of Santa’s pedigree took until September 2008, when the IAU officially accepted the Brown team’s proposed name, Haumea, but listed the Institute of Astrophysics of Andalusia as the place of discovery—without officially crediting either group for the sighting.
In some ways the best parts of the book are Brown’s unabashed self-descriptions. We see geek love in all its glory, beginning with his non-courtship of Diane Binney, the leader of science-themed travel groups for the Caltech Associates who asked him to give a tour of the Keck telescopes in Hawaii. When a coworker pointed out that she seemed to be paying a lot of attention to him, Brown replied, “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, on the last night of the tour, Brown and Binney found themselves alone on the beach some time after midnight. Brown pointed out the Southern Cross and Saturn, and they talked. Writes Brown, “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.”
The discovery of the potential tenth planet, provisionally named Xena, coincided with Diane’s pregnancy with their daughter, provisionally named Petunia. Xena was discovered in January 2005, just as it was about to go behind the sun, from whose glare it would not reemerge until September. Petunia was scheduled to appear on July 11, and the paper on Santa (discovered on December 27, 2004) was coming due as well. Brown slipped into hyperdrive, with one eye fixed on the calendar. “My goal was to get a paper on Santa finished before the birth of Petunia, since I still had a little free time. Her due date was now only three months away.”
But how accurate are these due dates, really? Nobody he asked knew. “If I was at a dinner party with Diane and the subject of due dates was broached, Diane would turn to me with a slightly mortified look in her eyes and whisper, ‘Please?’ I would rant about doctors. About teachers. About lack of curiosity and dearth of scientific insight. . . . Inevitably the people at the dinner party would be friends from Caltech. Most had kids. . . . As soon as I started my rant, the fathers would all join in: ‘Yeah! I could never get that question answered, either,’ and they would bring up obscure statistical points of their own. The mothers would all roll their eyes, lean in toward Diane, and whisper, ‘I am so sorry. I know just how you feel.’” There’s no gender bias here: “My female graduate students wanted to know the answer to my question, too, and were prepared to rant alongside me.”
Besides appealing to anybody interested in the solar system or astronomy in general, this book should be required reading for all members of the Caltech community, as well as anybody engaged or married to one. —DS
On August 30, 2006, the Hubble Space Telescope took this image of Eris and its moon Dysnomia. By combining this image with another from the Keck Observatory, Brown calculated Dysnomia’s orbit and Eris’s mass, which is 27 percent larger than Pluto’s.
