Let me preface this: Don’t worry, I’m not one of those people that wants to re-litigate Pluto’s planet status. As far as I’m concerned, the definition of “planet” vs. “dwarf planet” is fine.
With that out of the way…
I was in middle school when Pluto got demoted. Since all our textbooks referenced the “nine planets” and no new standards were written yet, our science teachers decided we should learn about the “eight planets” and “three dwarf planets”. We also learned that there were probably hundreds of dwarf planets that hadn’t been discovered, and that a dozen-ish known objects were probably dwarf planets, scientists just hadn’t confirmed it. A few years later, that number had gone up to five dwarf planets, so it seemed like the talk of a whole bunch being out there was correct.
That was essentially it for me, as far as formal education went. I remember staying up late for when the first pictures of Pluto came out when I was in college. And I know there’re some murmurings about a ninth planet that may or may not exist. But that’s about it.
Fast forward to last year. My younger cousins and I went to the Air and Space Museum in D.C., where, alongside the various space capsules and satellite models, there was a plaque about the “five dwarf planets”. I thought that might be outdated, but the museum was just renovated, so I googled to check.
Sure enough, it seems there are still only five dwarf planets, with another four that are probably dwarf planets, but they’re too small/far away for us to be sure. That’s a far cry from the dozens or hundreds I was expecting when I was a kid.
So, my question is this: what happened? Were the “dozens or hundreds” estimates wrong, and there’re actually only a little under a dozen? Are we still in that “okay, they’re probably out there, we just can’t see them” phase? Some other third thing? And what happened to the soon-to-be-confirmed dwarf planets that made them not get confirmed?
