AT THE SMITHSONIAN

Astronomer Mike Brown Is the Guy Who Killed Pluto

Senior Editor

January 7, 2011

On the California Institute of Technology's Web site, a biography of Mike Brown ever-so-casually states that the planetary astronomy professor "specializes in the discovery and study of bodies at the edge of the solar system," as if he were making sandwiches. But, just think about it, what a job!

Since the 1990s, Brown has been studying slowly-moving objects in the outer solar system in hopes of discovering a new planet. When he and his team discovered Eris, the largest object identified in the solar system in 150 years, in January 2005, he thought his dream had come true. But the finding sparked a debate over the meaning of the term "planet" and the decided-upon definition—"a round object, orbiting the sun, that is gravitationally dominant within its own orbital zone"—not only excluded Eris but also demoted Pluto from "planet" to "dwarf object."

Brown writes about the experience in his ravely reviewed book How I Killed Pluto and Why It Had It Coming, released in December. I emailed with the astronomer in advance of his book signings at the National Air and Space Museum's main store this Sunday, January 9, from 2 to 4 PM, and at the Steven F. Udvar-Hazy Center's store in Chantilly, Virginia, on January 10, from 2 to 4 PM.

"Killed" is a strong word. Have people made you feel like a planet murderer?

It is supposed to be sort of a pun on Pluto, god of the dead, being killed. But my 5-year-old daughter knows that I killed Pluto and is mad at me. She has a solution, though. She told me if I find a new planet and name it Pluto then everything is okay.

How do you feel about the current definition of a planet?

Acknowledging that the eight planets are—by a huge margin—the most massive and dominant parts of the solar system and are the backbone on which the entire solar is constructed is good. Pluto only makes sense as a planet in the cartoon pictures on my daughter's lunchbox.

What did you enjoy most about the writing process?

I truly enjoyed getting to go back and piece together the way the science and my own personal life were evolving at the same time.

What do you hope readers take away from the book?

I, of course, want readers to understand why Pluto really did have it coming, but more than that I want them to come away with a little of the joy and fascination that there is in everything in the universe, from planets and galaxies and stars, to the development of language, to the history of understanding of our place in the universe.