I should begin by saying that I don’t think the International Astronomical Union should actually change their minds about what qualifies as a planet. I have never been on that side. I have a solution that gets around that problem entirely.
Here’s the conflict as I see it; astronomers and non-astronomers mean different things by the word “planet.” Astronomers have always meant “a large object that directly orbits a star,” but until recently didn’t have a clear dividing line between what is large enough to be considered a planet, and what isn’t. This was actually a big problem, because scientists need precise definitions. When somebody says, “I discovered a new planet,” they need a clear, standardized definition of what that means, so they can make predictions from that statement. They need to be able to apply statements about planets to everything that is called planets. When one scientist says, “I learned this new thing about planets,” the other scientists listening need to know exactly what the first scientist meant, so when they run off to try to disprove the new thing, they are actually disproving the same thing that the first scientist studied.
Non-astronomers, on the other hand, pretty much meant, “one of those things in our Solar System that I care about.” After all, who learns about the dwarf planets in elementary school? How many know the name of an asteroid, or a moon that isn’t ours, or a comet that isn’t Halley’s? How many people know the name of a star? We like outer space, in theory, but we also don’t have much to do with it. The planets were like little glowing ambassadors, close enough to home to be comfortable and familiar but distant and exotic enough to inspire the imagination. Even for people more literate about astronomy, for so many the planets were the first things they learned about, the gateway drug to a world of gloriously unprofitable contemplation of the heavens. We love the planets. Pluto, in particular, got to be the little brother at the end of the line. He’s popular for the same reason that everybody loves the runt in a litter of puppies. He’s a little different and really cute. Being told that he wasn’t a planet felt like being told to forget about him, and we didn’t want to do that.
So how do we reconcile these two different definitions? Simple. We don’t have to. After all, you’ve probably heard that tomatoes are fruit, but do you ever actually call them that? Not unless you’re a botanist talking about them in a scientific context. They are only fruit by the scientific definition, “part of a plant’s reproductive system that includes and contains the seeds.” In everyday English, we don’t care about which part of the plant a tomato is, we care about whether we can eat it and how it tastes, and it doesn’t taste sugary enough for the word fruit, so we call it a vegetable.
That’s not even the beginning of examples. Practically every science has some term that they use in a sense that is either more precise or completely different from how it is used in everyday English. These words are different because they serve different purposes in different contexts. Biology; koalas are marsupials, but sometimes we call them koala bears because they look like teddies, and glass snakes are part of the lizard suborder, but we call them snakes because seriously, they look exactly like snakes. Chemistry; an element is a pure substance made of only one type of atom, but it has half a dozen other everyday definitions, including “a part of something else,” “a natural habitat,” and “something the benders can manipulate on Avatar; the Last Airbender.” Sociology; did you know Americans don’t live in a democracy? A democracy is a system of government where the people directly vote on decisions. We only elect the people who vote on decisions but are rarely directly involved in those decisions themselves. That makes us a republic. Except, once again, everyday language blurs the line between republic and democracy and we use the two interchangeably.
So why is it that when it comes to planets, we are all sitting around waiting for scientists to change their technical language before we adjust our everyday, cultural language? Scientific words aren’t actually any more “real” than other words. They are just words. They are a way to communicate an idea to another person very quickly. Astronomers picked a jargonistic definition that worked for them, and that’s fine, they needed to do that, but we, as a culture, can come to our own decision about what the word means in the world of colloquial language.
I can think of two ways to do this. Number one, we just decide that we will continue to consider Pluto a planet. Pluto is a part of our history. We really like Pluto. Or, if you prefer, Pluto is culturally significant to us; culturally significant is just a way to say “we really like it” but with three extra syllables. This is probably the simplest route. In a sense, people are already doing it, the only change would be that anybody who is writing angry letters to the IAU can stop now.
The second method is a little more complicated, but personally I prefer it and it’s going to be the one I push for. We decide that dwarf planets are still basically planets. Pluto is a planet, and so is Eris, Ceres, Haumea and Makemake. The IAU didn’t subtract a planet, they added four more! I’ve been reading up on the dwarf planets lately, and they’re no less likeable than Mercury, Venus or Neptune. Take Ceres. She’s the only known dwarf planet (or, you know, planet) in the asteroid belt, and also the smallest planet. Back in 1801, she was discovered, labeled a regular planet, and then straddled the line between asteroid and planet for about fifty years, before being officially dropped from textbooks. So if you think Pluto’s story is sad, think about Ceres, forgotten and lonely for over a century and a half.
Ultimately, though, it won’t be me making that decision. Cultural decisions are made collectively. We decide which words we use and how we use them. We create their meanings. If we decide we like a little trans-Neptunian ball of rock and ice enough to call it a planet (colloquially speaking) then we’re the only ones stopping ourselves from doing just that.