The Pluto Files

November 3, 2008
From Pluto's 1930 discovery to the emotional reaction worldwide to its demotion from planetary status, astrophysicist, science popularizer and Hayden Planetarium director deGrasse Tyson (Death by Black Hole
) offers a lighthearted look at the planet. Astronomical calculations predicted the presence of a “mysterious and distant Planet X” decades before Clyde Tombaugh spotted it in 1930. DeGrasse Tyson speculates on why straw polls show Pluto to be the favorite planet of American elementary school students (for one, “Pluto sounds the most like a punch line to a hilarious joke”). But Pluto's rock and ice composition, backward rotation and problematic orbit raised suspicions. As the question of Pluto's nature was being debated by scientists, the newly constructed Rose Center for Earth and Space at the Hayden Planetarium quietly but definitively relegated Pluto to the icy realm of Kuiper Belt Objects (cold, distant leftovers from the solar system's formation), raising a firestorm. Astronomers discussed and argued and finally created an official definition of what makes a planet. This account, if a bit Tyson-centric, presents the medicine of hard science with a sugarcoating of lightness and humor. 35 color and 10 b&w illus.