The Pluto Files, by Neal deGrasse Tyson

This was a really interesting read. Although you might find that Tyson deals more with personal mail he has received and some of the discussions with other astronomers takes a large chunk of the book. But with that said the book is very informative.

The main controversy came when a new Planetarium that Tyson was working with decided to not include Pluto in their displays of the "planets" of our solar system. The main reason was because they were not convinced that Pluto can hold planetary status.

Our solar system has four Terrestrial planets, Mercury, Venus, Earth and Mars. Then it has what are classified as Jovian (gas giants) planets, Jupiter, Saturn, Uranus and Neptune. That left Pluto out on it's own as an Ice Ball in space, not fitting with either of the two main classifications of planets.

There is a good discussion about how Pluto was originally discovered and then excellent material describing how with increasing sophistication of equipment that Pluto was downgraded in size several times, taking it from a large planet to a small "ice rock" in space.

Then the discovery of the Kuipter belt of asteroids sent another frenzy through the astronomy community. There were items out there as big as Pluto that also had a somewhat regular orbit around the sun. So what to do?

The answer is very interesting and I am particularly interested in their diagram of figure 4.9 on page 91 which shows 8 "dwarf" planets (including Pluto). One is larger than Pluto and six are smaller. But they are all past Neptune and have orbits.

So, I was left with do we have 8 planets in our solar system or do we have 16 planets? That is an interesting question.

You'll need to read to find out the answer.

Taken all together this was a very fascinating book.