The man who demoted the planet Pluto

An image taken by the Hubble Space Telescope shows Pluto (center) with its newly named moons. An image taken by the Hubble Space Telescope shows Pluto (center) with its newly named moons. (Nasa via Associated Press)
By Chuck Leddy
Globe Correspondent / January 1, 2011

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Mike Brown, a professor of astronomy at the California Institute of Technology, has written the strangest “addiction’’ memoir you may ever read. Brown’s personal narrative doesn’t explore demons like drug or alcohol abuse, nor does he offer any shocking private revelations. Brown’s addictions are twofold: first, finding faraway objects in the sky, and second, understanding the difference between planets and other large objects in space. In his Ahab-like search for a 10th planet, Brown would transform our understanding of what a planet is, thereby triggering a historic reexamination of Pluto’s status as our ninth planet.

Describing Brown as an obsessive researcher is like saying that workaholic New England Patriots’ head coach Bill Belichick is somewhat concerned about winning. It doesn’t begin to tell the story. To gauge Brown’s obsessive style as an astronomer, it helps to see how he acts in his free time. At home, Brown spends hours observing his newborn daughter, pondering big questions like, “Why did she cry? When did she sleep? What made her eat a lot one day and little the next? . . . I recorded data, plotted it, and calculated statistical correlations.’’ Brown even writes a computer software program to generate reports on all aspects of his daughter’s life and maintains a website filled with his observations and theories.

The arduous process Brown uses to find large objects in the sky makes finding a needle in a haystack sound easy. Using massive telescopes, including the Hubble Space Telescope, Brown slowly scans the skies, taking photographs and examining them for moving objects. Brown writes massive computer programs that help him filter the photos, then spends countless hours manually scanning the photos. In one typical instance, Brown spends months examining 8,761 images flagged by the computer as potential finds. After all this work, often staying up deep into the night, Brown discovers exactly nothing. Yet he keeps looking.

Brown’s work ultimately pays off. He finds a massive object he believes is larger than Pluto. “Nothing this large has been found in the solar system in more than 150 years,’’ writes Brown. Should this “bigger-than-Pluto’’ object be classified as a planet, or if not, should Pluto itself be de-classified? The story escalates when Brown discovers other massive objects in the sky. Should they be classified as planets, too? The whole question gets submitted to the International Astronomical Union, which must decide either to classify Brown’s new discoveries as planets or to re-define the term “planet.’’

Brown’s scientific principles far outweigh his desire for personal advancement. When the IAU decided to define “planet’’ to include Brown’s new discoveries, Brown didn’t uncork the champagne but instead became the strongest opponent of the IAU’s position. Brown publicly advocated a more restrictive classification of “planet,’’ one that would exclude both Pluto and his own discoveries. As Brown explains it, “The debate about whether or not Pluto is a planet is critical to our understanding of the solar system. It is not semantics. It is fundamental classification,’’ a core part of science.

In the end, Brown’s restrictive view triumphed. If Pluto had remained a planet, Brown notes, then we would need to declare perhaps a few hundred other planets. The classification of “planet’’ would soon become murky. We’re all better off for this man’s breathtaking commitment to science. So he didn’t discover a new planet after all and may have killed Pluto in the process, but this guy might be the finest scientist alive today.

Chuck Leddy, a freelance writer in Dorchester, can be reached at


By Mike Brown

Spiegel & Grau, 267 pp., $25