The Case for Pluto covers essentially the same material as The Pluto Files but in much greater depth on the personal side and a little more detail on the scientific side. I liked this book better because of that greater depth, but it was still a pretty dry read and had very few funny bits to lighten things up. The author makes two basic arguments for considering Pluto a planet. The scientific argument is that all objects with enough gravity to become round should be planets, because this is a non-arbitrary physical property. And of course the second argument is a sentimental look at Pluto’s historical significance. While the sphere argument is somewhat compelling, it does have the unfortunate problem of creating tons of planets (many asteroids and Kuiper belt objects meet this criteria, as do many moons), making planet a large enough category it’s useless without sub-categories. Although unconvinced by the main point of this book, it was an interesting read and I very much enjoyed the final chapter describing future research directions. I would recommend it to anyone just looking to learn some more facts about Pluto.