The Timblog: "Death" to Pluto

When I was a kid in school I learned about the nine planets in the solar system. They didn't make much of an impact on me, so as an adult I couldn't tell you much about them. I knew Venus and Mercury were closer to the sun, Mars was our neighbor who kept invading, Jupiter was the big one, Saturn was the one with rings, and Uranus was a gold mine of juvenile jokes. (Q: How is the Starship Enterprise like toilet paper? A: They both fly around Uranus and pick up Klingons.)

Pluto wasn't really on my radar. It was just one of the planets. I didn't pay attention to the fact it was the smallest, or the most distant, or the "newest" (in terms of our discovery of it), or the only one discovered by an American.

So when I heard in the news a few years back that Pluto was no longer a planet, it didn't much bother me. Oh, isn't that interesting, I thought. They found things bigger than Pluto out beyond it, so they either had to include those new objects as new planets or demote Pluto. That's only fair. Scientific progress and all. When my mom was born there were only 48 states. Now there are 50. Things change.

But people were really, really upset when the astronomers in the International Astronomical Union (IAU) voted to demote Pluto to the status of a "dwarf planet." They didn't understand how scientists could just "kill" Pluto like that. Who gave them that power?

Science isn't about emotion or tradition or protecting those cherished memories from your school days. It's about cold hard facts, and changing those facts based on new evidence. But people really don't seem to like that aspect of science.

Seriously? A protest for the classification of a celestial object? It's not like baby asteroids are being clubbed to death.

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I was reminded of the whole Pluto controversy by an awesome book I just read, How I Killed Pluto and Why It Had It Coming by Mike Brown.

Brown is the astronomer who discovered Eris, the planet-like thing out beyond Pluto that was larger than our ninth planet. He also discovered a lot of other objects about the same size. It was these discoveries that led to Pluto's "death" as a planet. As the blurb on the book jacket says:

Mike Brown is the funniest, smartest, and most surprisingly poetic Caltech astronomer who ever made my daughters cry. Certainly their happy nine-planet childhoods were worth sacrificing for this truly fascinating and engaging read.

I couldn't agree more, although it stuns me that someone would actually cry over Pluto's fate. Although the book is funny and liberally uses the metaphor of Pluto dying or being killed, Pluto is no more dead or alive than it ever was. It was just re-classified based on new data. No one "killed" it.

The book is indeed a fascinating read. It mixes discussions of planets and our solar system (I should have been an astronomer!) with Brown's own life-- the sweet courtship of his wife, the amazing birth of their daughter, and the professional triumphs and setbacks that accompanied his planetary research. He tells a good story. There's even controversy and intrigue and-- get this-- an evil astronomer nemesis from Spain who tries to steal credit for Brown's discoveries!

The idea that there's an evil astronomer is as funny as the idea that there are evil cartographers or meteorologists.

The book is the perfect mix of science, human experience, and controversy.

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Brown spends a lot of time in the book trying to define what a planet is. Most of us probably couldn't give a precise definition of a planet. At the end of the book Brown says that planets are a concept, not a definition: "when people say 'planet,' they mean, I believe, 'one of a small number of large important things in our solar system.' "

In the early 19th century, a few new planets were discovered between Mars and Jupiter. For a while the solar system had 12 planets. But when 15 more of these planet-like objects were found in rapid succession, astronomers realized they couldn't all be planets. It turned out that scientists had simply discovered an asteroid belt between Mars and Jupiter. (This must be why Martians always attack Earth instead of Jupiter-- no asteroid belt to get in the way.)

So after they sorted out the whole asteroid belt thing, scientific progress required that they re-classify the solar system based on new knowledge. The same thing has happened with Pluto. When we thought Pluto was just a lone object at the edge of our solar system, perhaps it made sense to think of it as the ninth planet. But now that we know there are a lot of Pluto-like objects out beyond it, that it is merely a part of a larger belt of objects (known as the Kuiper Belt) on the rim of the solar system, it makes sense to re-classify it.

As Brown says, "Going from nine planets to eight planets would be scientific progress."

As kids learning about the solar system, we like to have simple facts. The Earth is the third planet from the sun. The sun is 93,000,000 miles away. There are nine planets in the solar system. But after reading this book I realize it's much more complicated than that. The solar system, as we now understand it, is broken down into terrestrial planets (Mercury, Venus, Earth, Mars), the asteroid belt, giant planets (Jupiter, Saturn, Neptune, Uranus), and the Kuiper Belt (Pluto, Eris, and dozens other "dwarf planets.")

Ironically, Brown had as much to lose as anyone by "killing" Pluto. Since he was the one who had discovered the "tenth planet," he could have received much fame and notoriety for that honor. Instead, he chose scientific logic over personal gain. He did the right thing, and for that I am deeply impressed.