“Is Pluto a planet?”, David Weintraub

No, apparently. Or at least there isn’t a meaningful definition in sight that will make Pluto a planet without also including about 15 other objects in our solar system. Although Weintraub eventually comes down on this inclusionist side, the overall taste the book left in my mind was: No, Pluto is just a large Kuiper Belt object.

“Pluto earned its status as a planet by accident”, we learn, because the people who happened to find it were really wanting to find one to explain the supposed differences in Uranus’ and Neptune’s predicted and observed orbits by the new planet’s gravitational tug. They saw Pluto, called it a planet and the name stuck.

This book raised more questions for me than it provided answers, which I really enjoyed. For example: Could you measure the parallax of a train that looks like it is moving when you are on the one pulling away? How come I didn’t know that the Moon does not actually orbit the Earth but they both orbit a point very close to the centre of the Earth? Who named Pluto? Can you observe the change in planets from prograde to retrograde motion or is it theoretic? Why were the moons of Mars called Fear (Phobos) and Panic (Deimos)? Answers, anyone?

Weintraub takes the reader on a tour through astronomy’s history and while he is very thorough I was hoping for a style slightly more awe-inspiring, given the suitable topic. Thinking about Pluto’s moon Chiron and its likely fate of a change in orbit, “perhaps directly into the Sun or onto a collision course with Earth or Jupiter or Saturn” – this is the kind of spine-tingling sense of foreboding you can only really get from astronomy and I love it.