Pluto Should Never Have Been a Planet

I just finished reading Mike Brown's How I Killed Pluto and Why it had it Coming, and it was a fantastic read.  It got me thinking of so many things; scientific progress and history, how the public perceives scientific ideas, becoming entrenched in a way of thinking, distress over change, and how so much of education seems to be storing data in memory rather than learning algorithms (and man for some reason I've really been connecting with my inner computer scientist lately) are just some of the highlights.  It's amazing how much depth there is to the trivial or technical classification details of a rock out there past Neptune.  There's one more aspect of the book that I loved, Mike Brown's humanity in his love for his wife, his daughter, and the sky, but I think I'll write about that in detail later.

I remember when Pluto was reclassified.  Many jokingly consoled forlorn Pluto, kicked out of the planet club by the big boys.  After reading the book I find it odd, why did no one talk about Eris (the Kuiper belt object actually larger than Pluto which theoretically could have been the tenth planet)?  Why did no one bring up Charon, Pluto's moon which is almost as large as Pluto?  Why did no one discuss what exactly it meant to be a planet, and how exciting it was that we were learning more about our solar system in finding so much out there in a whole new asteroid belt out beyond the gas giants, the aforementioned Kuiper belt?

I've groused before on this blog about the dreadful way mathematics is taught, perhaps it's time to get some of that ire up for science as well.  One thing the book made clear is that we all learned that the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and (as we learned at least) Pluto.  Did any of us ever learn what a planet is?  I think the 'Pluto controversy' pretty clearly indicates no, we didn't.  If we had we would have always found Pluto's planethood a little odd.

Pluto's moon doesn't orbit around it, they orbit around each other.  Pluto's orbit is eccentric from the other planets.  Pluto is smaller than many planet's moons, including Earth's.  To kids and creatives that might make Pluto mysterious and fascinating (it did to Mike Brown as a child), but to scientists and logical thinkers it seems misplaced in the solar system.  And indeed it was.

But no one really seemed to feel that way.  We all sort of felt bad for Pluto, and some people might have even been upset.  I think there's two major components why.  The first is, as I alluded to, the way we learn science.  The next is our unwillingness to accept change.

Thinking about the Pluto controversy I am brought to worry that we are often taught 'the way things are'.  Mike Brown talks about trying to get students out of the mindset of, "Give me the answers I need to know for the test".  The unfortunate implication is that something gets them into this mindset in the first place.  Standardized testing is a convenient and popular target for modern problems in education, but I'd feel remiss if I didn't mention that of necessity it requires students to memorize and later regurgitate facts, and testing any deeper thought processes is at the very least much more difficult.

I read a NYT article that talked about why teaching the difference between fact and opinion like we currently do in schools is morally perilous, as well as simply fundamentally misguided.  It points out interesting ideas, like how teaching children that facts are provable and true causes them to equate truth with provability, even though they're very different things.  I think a focus on 'facts' in science class also carries a dogmatic implication for young students.  Science is always true because we collected evidence for our ideas.  Here's where the distress comes up; Pluto no longer being a planet means facts can change as our understanding does.

And that opens up a whole new can of worms in our minds.  It forces introspection and meta-cognition, in which sadly most of us are loath to participate.  It creates a crisis of certainty, because after all if Pluto being a planet isn't true what other tidbits we learned might not be true?  Doubt is, unfortunately, scary to many.  We're unwilling to change our thinking, to update our knowledge, to print retractions or errata for our memories.  This is why teachings of humility are so important.  They allow us to maintain our sense of self and identity even when we're forced to change our thinking, context, or experience.

A great idea that came together for me when I read The Island of Knowledge is that science must necessarily be the least sure of itself of all human endeavors or reservoirs of understanding.  It must be forever willing to except new evidence or observation which proves previous ideas wrong, and moreover perhaps must forever be seeking these out.  No less than the well known and liked Neil DeGrasse Tyson recently said in a podcast I listened to that the greatest problem is always dogmatism, because it ends a conversation and makes learning from others difficult or impossible.  Let's take this to heart, accept that Pluto should never have been a planet, and rejoice in the fascinating newly unfolding mysteries of that Kuiper belt.