The Pluto Files

Review by John C. Snider © 2009

Answer quickly: Pluto – planet or not a planet???  Few questions have so divided America as the decision by astronomers to reclassify our formerly ninth planet as a mere “dwarf planet”.  Now, Dr. Neil deGrasse Tyson (director of the Hayden Planetarium and outspoken rationalist extraordinaire) looks at the controversy, particularly from the “pop culture” angle, and recalls how he (as the foremost Pluto demoter) took withering fire from schoolchildren and fellow astrophysicists alike. 

Americans have an inexplicable fondness for Pluto.  True, it was discovered by an American (Clyde Tombaugh) in 1930, but we know far less about Pluto than any of the other major bodies in our solar system.  For decades it was nothing more than a dot in photographs – even today the best image of Pluto (and its three associated moons) is just a pixellated blur.  Nonetheless, every schoolchild knows there are nine planets in the solar system.  Not eight, not ten, not some number dictated by the vicissitudes of ever-changing scientific knowledge.  No, there are nine – count ’em N-I-N-E – planets orbiting our sun.  Period.  End of story.

Except for the minor detail that, until just a couple of years ago, astronomers had never actually come up with a hard definition for “planet”.  Sure, most folks understood that planets were, generally speaking, big, round things that orbit the sun.  Everything else was a moon, an asteroid, or a comet. 

But Pluto was the platypus of the solar system.  It was big and round like a planet, but it had an odd orbit, that was both askew from the plain of the other planets and highly elliptical, falling partly inside the orbit of Neptune.  A growing consensus among professionals within the astronomical community – including Tyson - was that Pluto was not really a planet.  And so, when making decisions about the design of the new Hayden Planetarium (located on Central Park West), Tyson made the controversial choice to show only eight planets.  Shortly thereafter (and if you’ll pardon the pun) a storm of cosmic proportions began raining down on Tyson’s head.  In The Pluto Files, Tyson details the public and professional outrage, and includes numerous newspaper cartoons, song lyrics and even letters from dissatisfied schoolchildren.

Granted, Tyson may have jumped the gun a little, but six years after the new Hayden opened in 2000 sans Pluto the International Astronomical Union adopted the first-ever official (and more or less objective) definition of a planet that (for now) relegates Pluto to the growing number of “dwarf planets” that exist beyond the orbit of Neptune.

Tyson writes with humor and more than a little sympathy for those who think Pluto got the cosmic shaft.  The Pluto Files (a thin volume published in January 2009 in hardcover by W.W. Norton & Co.) is both a fascinating glimpse into the life of a professional astrophysicist and an indispensable look at the intersection between science and popular culture.

The Pluto Files is available at and

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