Bye, Bye Pluto - We Hardly Knew Ye at All

Here’s a quick trivia question for ya: How many planets are in our Solar System? A couple weeks ago the correct answer would have been nine. Now, it’s eight. Or 11, if you count Dwarf Planets. What? And you thought this was an article about only computer stuff. Usually it is, but I couldn’t pass up the opportunity to talk about this major milestone in Astronomy: we finally know what a planet is. And Pluto isn’t one.

So, what is a planet? Is it just any old big rock circling the sun? Were that the case, then there would be many more than just nine planets. Maybe a planet is a big rock that circles the sun and has an atmosphere? Nope. Hmmm… Is a planet a big rock circling the sun that someone arbitrarily decided to call a planet? Yes, that’s it! Until just a few days ago the term ‘planet’ meant, essentially, nothing.

Well, enough is enough. The International Astronomical Union decided to get together and have a vote to decide once and for all what it takes to be called a planet. I can only imagine the scene: hundreds of white coated, eyeglass-wearing nerds arguing over fine details and drawing huge equations on a large row of whiteboards. I bet more than a few pocket protectors were emptied that day. Man, I would have loved to be there…

After the dust settled, Pluto was demoted to Dwarf Planet status. Two other celestial bodies (Xena and Ceres) were moved into the same category, making the number of dwarf planets three. All of a sudden, textbooks, posters and science fair projects the world over were rendered obsolete—there were now only eight planets in our little corner of the Universe.

I remember how I was taught to remember the planets in order: My Very Educated Mother Just Sent Us Nine Pepsis. The first letter of each word in that sentence serves as a reminder for the planet in that position: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Thanks to the IAU, now we gotta come up with a whole new way to remember the planet names in order. Oh well, how about this: My Very Educated Mother Just Sent Us Nothing.

As always, if you have any questions or suggestions for future articles, please email me at mike@MikeBryant.com.