It’s been four years since the International Astronomical Union kicked Pluto out of the Planet Club. Most people may be too busy reading their horoscopes to care about actual planets, but for the rest of us, this Pluto thing isn’t over yet. Why do we care about a speck of light four billion miles away? Principle, mostly. The big and powerful are picking on the small and weak. Also, Pluto has a name. You don’t start calling your cow Millie and then send her to the slaughterhouse, do you? (Well, I wouldn’t.)
Feelings aside, the reasons for Pluto’s demotion to dwarf planet are unsound. The IAU issued three criteria for qualification as a planet: (1) The object must be massive enough to form a sphere. (2) It must circle the Sun. (3) It must have succeeded in “dominating the neighborhood” by clearing its orbit of debris. I’ll address these, but first let me state the obvious. Pluto is tiny and that’s really what this is about. Put Uranus into Pluto’s orbit and Uranus would still be a planet.
When astronomers try to demonstrate the absurdity of including Pluto, they invariably resort to visual comparisons, representing Jupiter as a beachball, for example, and Pluto as a poppy seed. But could we apply this logic to anything else? Alaska is 572,000 square miles. Rhode Island is 1,545. Should we decide, by a show of hands, that Rhode Island is now just a dwarf state? The largest mammal, the Blue Whale, is 110 feet long and weighs 190 tons. The smallest, the Hog-nosed Bat, is 1.3 inches and 0.07 ounces. The ratio of Jupiter’s diameter to that of Pluto is 63 to 1. The ratio of the whale’s length to the bat’s is much larger. Yet they’re in the same class and no one’s been expelled.
Some scientists argue that we can’t call Pluto a planet because it’s smaller than several of the Solar System’s moons, including ours. But this comparison, too, is weak. Vancouver Island, with an area of 12,000 square miles, isn’t a Canadian province, but rather a part of British Columbia. Prince Edward Island, at 2,200 square miles, is a province. To take the point to the ridiculous, Vatican City is a country, yet it measures less than one square mile. The bat previously mentioned is smaller than many insects.
What makes the decision especially irritating is that they changed the rules in the middle of the game. It seems sneaky. I had never thought of astronomers that way before. I bet Galileo wasn’t sneaky.
The rule that a planet should be spherical makes sense, but if something were to crash into Mercury, leaving it shaped like the letter D, would Mercury no longer be a planet? Besides, Pluto is spherical.
The second rule says the object must orbit the sun. Pluto orbits the sun. Okay, its orbit is a little wacky, but maybe it was involved in some sort of collision. Maybe whatever knocked Pluto off course was headed for Earth, and we were saved by the little guy. Is this how we show our appreciation?
Rule number three seems to have been the clincher. But I think they dreamed it up just so they could give Pluto the boot. A planet must dominate the neighborhood and clear its orbit of debris. There are street gangs that dominate their neighborhoods; that doesn’t make them good citizens. And what about Saturn? It hasn’t cleared its orbit. In fact, Saturn drags debris around with it. Now I like Saturn as much as anybody, but it shouldn’t get special treatment just because it’s big.
I think the IAU is really trying to say that Pluto is too odd. Well that’s not good enough. I know plenty of people (a few in my own family) who would be banished from the human race if that were a valid reason. Hawaii is the only state that’s an island; isn’t that odd? The nation of Lesotho is completely inside of South Africa. Pretty weird. And the city of Istanbul is on two different continents.
If you wanted to, you could come up with a rule that eliminates any planet. Mars is orange. Jupiter has no solid surface. Venus is too hot. Neptune is the only planet that was discovered on a Wednesday. Earth is the only one that allows furniture store owners to star in their own television commercials.
Astronomers respond by saying they have discovered objects similar to Pluto, some even larger, orbiting in its vicinity. If Pluto is allowed to stay, don’t we have to let those others in, too? No. They missed the deadline. Sometimes you show up late and lose your chance. Is it silly to describe objects that are billions of years old as being late? No sillier than mentioning a Blue Whale and a Hog-nosed Bat in the same sentence.
Mostly Bright Ideas 
Marie M
May 18, 2010
This issue didn’t bother me much before, but now you’ve made me feel really bad for poor little Pluto.
I’d like to see you submit this entry to an astronomy journal or at least an astronomy association’s newsletter. I’m loving your blog and want more people to read it–whether or not they can solve all your world’s problems, they’ll surely be amused to see them through your eyes–and maybe recognize an issue or two in their own world. Thanks for sharing!
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bronxboy55
May 18, 2010
Thanks, Marie. I did send it to Smithsonian Magazine, waited three months, then got a polite no thank you. I’m kind of liking this blog thing — I decide it’s going to be published and ten seconds later, it is. Also, as the posts accumulate, the collection takes on the appearance of a portfolio, with everything in one place. I think you’d be a great blogger, by the way.
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Margaret Reyes Dempsey
February 7, 2011
This Pluto thing made me crazy. My Very Educated Mother Just Served Us Nine…
Nine what?
No more Pies. They didn’t have to be pumpkin.
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bronxboy55
February 7, 2011
You’re really into some ancient history here, Margaret. I think this was one of my very first posts.
Did the Pluto thing really upset you? I haven’t heard much about it lately, so I guess the controversy has died down.
My Very Educated Mother Just Served Us…… Nothing.
Which, in one sense, is better than Pumpkin.
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Margaret Reyes Dempsey
February 7, 2011
It did bother me. Once a mnemonic device has been invented for something, you can’t go and ruin it. Even my son, who is only eleven, is annoyed by it. His early planet kits/toys came with Pluto. Then, at some point in elementary school, he was taught it wasn’t a planet. I guess I would have been one of the crazies screaming, “Whaddaya mean the earth’s not flat?”
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Wyrd Smythe
January 22, 2013
It was a sad day, indeed, but over time I’ve accepted it. The real clincher in my mind is that, IF Pluto is a planet, so are a whole bunch of other objects out there that have the same basic stats as #9 (a few are even bigger).
So look at it this way: one less planet to memorize versus having to memorize a whole crapload more.
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bronxboy55
January 23, 2013
But I’d already memorized it. Now I have to remember that Pluto isn’t a planet. What’s the mnemonic for that?
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Wyrd Smythe
January 23, 2013
The IAU revised the old one to: “My Very Excellent Mother Just Served Us Nachos” (used to end “Nine Pizzas”).
Counter-reaction from angry Plutonians provided, “Many Very Educated Men Just Screwed Up Nature.”
My little contribution: “Planet Lost Under Traitorous Observations.”
I never really grokked mnemonics… I found them harder to remember than the thing they were supposedly making it easy for me to remember. Roy G. Biv? Huh?? Red, Orange, Yellow, Green, Blue, Indigo, Violet. Easy.
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bronxboy55
January 24, 2013
I guess you haven’t heard: Martha Stewart recently announced that violet is no longer a color. Apparently, it’s too similar to indigo, and has such a short wavelength. Well, Martha didn’t actually mention the wavelength, but she did say that violet tends to clash with too many fabrics, and doesn’t work well with hardwood floors.
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Wyrd Smythe
January 24, 2013
Yeah, but I don’t take advice from convicted criminals.
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