This book, the Pluto Files, is an entertaining and informative introduction to the planet Pluto and its fate as a planet. Neil DeGrasse Tyson is not only a famous Astrophysicist but a great populariser of science, and he is carrying on Carl Sagan’s work impressively. I love Dr. Tyson’s Cosmos series and I really hope to see a lot more of it.
As we all know Pluto is no longer considered a planet and Neil DeGrasse Tyson might have helped Pluto’s demise as a planet with the construction of the Hayden Sphere at the Hayden Planetarium. Until recently there was no formal definition of what a planet is and that presented a problem for the involved scientists and for Pluto. The book tells you about how Pluto was conflated with Planet X, how it shrunk in size as more became known about Pluto, how it’s orbit is unusually eccentric, and that it has not sufficiently cleared its orbit of debris, and that it could be considered to be just the largest known Kuiper belt object, and that Pluto was not named after Mickey Mouse’s dog (but rather the other way around). Neil DeGrasse Tyson is of the opinion that Pluto should not be called a planet, but his view is nuanced and based on science, and he is not taking himself too seriously. He is fair, and he tells us about the problem with humor and with respect for all viewpoints. He gives us an overview of the various discussions and opinions that scientists had on the topic, including that of Alan Stern, the man behind the New Horizons project, and a graduate from the school my son just graduated from.
Unlike Dr. Tyson, I am not an expert on the topic, but even after reading this book, I find myself not entirely convinced. What is a Planet is about how to label something. In addition to scientific considerations it is also culture, and therefore the view of the public matters. The alternative definition of a planet as a body circling the sun that is in hydrostatic equilibrium (big enough to squeeze itself into a ball) is also quite intuitive. I don’t think it is bad if Ceres comes back as planet, or if there are dozens of other Kuiper belt objects that will be called planets. That’s just exciting. Then you could actually impress someone by knowing all the planets. One thing that was not discussed in the book was how this is related to exo-planets. What shall we do with large exo-planets that have not cleared their orbit of debris? That’s another reason I think we might not have heard the last of this yet.
In any case, the book has lots of nice pictures, comical anecdotes, lots of interesting information and discussions, and it is a concise and entertaining read. Therefore I recommend this book.