The Pluto Files: the Rise and Fall of America’s Favorite PlanetBy Neil deGrasse TysonW.W. Norton, 2009It was a dark day for astronomy when the International Astronomical Union got together in Prague in 2006 and officially declared that Pluto was not, in fact, a real planet. The Union’s declaration talked about hydrostatic equilibrium and such arcana, but ever since hominid life first looked to the heavens, the planets have represented far more than repositories of astrophysical data. They’re embodied dreams, wandering across the night sky.Pluto, back when it was a theorized but unseen ‘Planet X,’ captivated the dreams of a 24-year-old kid named Clyde Tombaugh, who in 1930 combed the night sky with his telescope until he found the fabled ninth planet in Earth’s solar system. Tombaugh lived long enough to hear talk of possibly upgrading large solar objects – including some in the far-distant Kuiper belt of asteroids – to planetary status. Neil deGrasse Tyson, in The Pluto Files, his utterly winning biography of a planetary underdog, tells the story:

Clyde Tombaugh was still alive in the early 1990s. He saw the Kuiper belt omens, but fought them tooth and nail with cane in hand, using his cane not only as a walking aid but also as punctuation for the aggressive arguments he would make. Tombaugh had the most to lose if Pluto were classified as anything other than a full, red-blooded planet. In a December, 1994 letter to the editor of Sky & Telescope magazine (the monthly bible for amateur astronomers), Tombaugh declared: I’m fascinated by the relatively small “ice balls” in the very outer part of the solar system. I have often wondered what bodies lay out there fainter than 17th magnitude, the limit of the photographic [plates] I took at Lowell Observatory. May I suggest we call this new class of object “Kuiperoids”?Not knowing that objects larger than Pluto awaited discovery in the Kuiper belt, Tombaugh was unwittingly suggesting that Pluto become a Kuiperoid as well. In any case, astronomers are not likely to adopt a word that sounds like a contagious skin disease.

Tyson, the director of the Hayden Planetarium at the American Museum of Natural History, is a wonderful, witty guide for every stage of Pluto’s century of celebrity, although he’s far too indulgent of those anti-American exclusionists who’ve succeeded – temporarily – in ousting Pluto from its rightful place on millions of those concentric-circle solar system models in millions of kids’ rooms around the world. The Pluto Files is a fantastic book for enthusiasts of all ages, but I’m one person (and for obvious reasons, I suspect Mickey Mouse is another) who hopes Pluto’s final chapter has yet to be written.