Pluto: A Planet or Not

Pluto: A Planet or Not

By Bobby Neal Winters

Is Pluto really a planet or not?  We are going to discuss that, but first a tangent.

I think I was in about the 5th grade--certainly no older--when my teacher started a discussion in my class about whether school buses were yellow or orange.  I don’t know if there was an educational point she was trying to make or whether she was just bored, but we argued over the question like hungry dogs fighting over the body of a squirrel.

At the time, we had neither the linguistic skills nor the intellectual framework to discuss the matter which is kind of complicated.  First is to say that the perception of color is subjective.  We perceive color through structures in our eyes called cones.  There are different types of cones that give different singles to the visual cortex of our brains.  There is a certain amount of variation in the relative number of cones everybody has, so there is variation in what we perceive.

In addition to this, I can’t see through your eyes and you can’t see through mine, so when we see orange we might be--and I would say probably are--having completely different experiences.  I point at something and say “orange” and you nod in agreement we’ve created a word in the common language between us.  This agreement is pretty solid on the color of pumpkins, but it gets wobbly when we get to 5th graders discussing school busses. 

Let me stop before I start talking about wavelengths of photons and how Chickasaw and Scotts Gaelic will use a single for green and blue.  How boring I can be is unbounded below.

Because I am here to talk about whether Pluto is a planet. 

First off, this isn’t really a scientific question.  It is a fight over nomenclature where science speech meets the world of popular speech.

We get the word “planet” itself from the Greeks.  With TV thousands of years in the future, they sat staring at the sky and looking at the stars.  Most of the stars stayed put in relation to each other from night to night, but they noticed that some of them moved slowly with respect to the others.  They called these “wanderers,” but because they were Greek they used their own language and called them “planetes.”  The Greeks named the following as planets in this sense: Mercury, Venus, Mars, Jupiter, and Saturn.  

This definition of planet worked for a long time.  Then the telescope was invented and over the course of time astronomers discovered Uranus, Neptune, bunches and bunches of asteroids, and our little friend, Pluto.

We can start talking about composition, shape, whether an object has “swept out its orbit,’ and so on, but before we do, let us make note of the fact we have gone a huge distance from the Greeks.  They were looking at the skies with their bare eyes and noticed something.  We’ve brought in lenses, mirrors, radar, and robotic spacecraft.  

We’ve seen the things the Greeks called planets and can talk with much more nuance about what they are.  Mercury and Mars are balls of rock almost devoid of atmosphere, relative to earth.  Venus is a bigger ball of rock with a hellish atmosphere.  Jupiter and Saturn are huge balls of gas that have balls of rock circling them; some of the things circling Jupiter and Saturn wouldn’t be out of place in a line up with Mars and Mercury. 

Of the stuff we’ve found and catalogued since the Greeks, Uranus and Neptune are like Jupiter and Saturn, and the rest of it is just rocks of various sizes.  Earth is the biggest of these rocks (we’ve started thinking of our home as just another astronomical object!) and the rocks go down in size to specks of dust.  

The argument wound down to where do you draw a line between Earth and a grain of sand on the beach to planets on one side and non planets on the other.

Some of us are sad that Pluto wound up on the wrong side of the line.  This is because Pluto was discovered by an American and that makes it special to us. But, you know what, it can still be special to us regardless of what name is slapped on it.  We’ve sent the New Horizons probe by it and took some awesome pictures in 2015. It’s quite a place.

Whatever it is called.

Bobby Winters, a native of Harden City, Oklahoma, blogs at redneckmath.blogspot.com and okieinexile.blogspot.com. He invites you to “like” the National Association of Lawn Mowers on Facebook. )