Monday, September 29, 2008

Nine, eight, eleven, thirteen; I'm so confused!

How many planets are there? That's a simple question, right? Everyone knows there are nine planets! Lloyd even has a mnemonic device from school that he made up and still remembers: Most Vampires Eat Moldy Jeans Don't You Know Peter. I get the 'you' for Uranus and the 'know' for Neptune, but I'm not so sure about the 'don't' for Saturn. But wait, didn't they decide that Pluto isn't a planet anymore? So that's eight, right? Yeah, eight. Nine minus one equals eight. No question about it. Eight.

Weston has all these books about space and most of them predate Pluto's demotion, so we have been very careful to tell him that Pluto isn't a planet even if some books show it that way. This made us feel very smug and up to date on the latest planetary happenings.

Yesterday, he was wondering if Phobos has any volcanoes, Phobos being one of Mars' moons. In the course of looking it up, I discovered there are now eleven planets! What, you say?!?!?!? Yeah, me too! What are these extra three planets and how did they get into our solar system?!?!? As luck would have it, I was at the library yesterday afternoon and saw a new book called '11 Planets A New View of the Solar System'. I snapped it up and got the 411 on the planets.

WELL, it turns out that after considerable heated debate in astronomy circles, Pluto, Ceres and Eris are now considered dwarf planets. So eight (regular planets) plus three (dwarf planets) equals eleven planets. What, you never heard of Ceres or Eris? Me neither, but apparently they have been around quite a while. Ceres was actually discovered long ago and considered the fifth planet out for quite some time. Eris was discovered in 2003; you'd think I might have noticed. So that's eleven. For sure. The book says so and everything.

But, wait, that's not the end of the story! You'd think I might have learned not to be smug, but no. I thought I was right on top of it, until I was writing this, and I discovered there are two more dwarf planets: Haumea and Makemake, and to make it more complicated, some of the dwarf planets are considered plutoids. So, let's see: that's eleven plus two, so thirteen. But do I minus the four plutoids, back to nine? I'm so confused; seriously, I would have no idea how to answer if someone asked me how many planets there are. And don't even get me started on how many moons Jupiter has! I guess I will have to wait until Weston is a space scientist to find out for sure.

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