people act like Pluto was dealt a bad hand bc they thought it was a planet but later classified it as a dwarf but consider this: there are 4 other dwarf planets in the solar system that most people don’t even know the names of so Think Again before you think Pluto is underrepresented
look. look at these precious forgotten siblings
*sighs* why do I ever look at the notes on these posts. okay kiddos buckle up, y’all are in for an impromptu astronomy lesson on…….
THE KUIPER BELT
so here’s the dealio with our planets: the five we can see with our naked eye can only be seen because they’re v close and/or v big. when we found Uranus and Neptune when we started getting p good with telescopes, but we also knew to look for them because calculating planet orbits were inaccurate without also factoring in the possibility that there were more planets beyond them. this is also how we knew to keep looking for the ninth planet (which we still have not found btws) and why we were looking at pictures of the night sky when we found Pluto
But here’s the thing: Pluto is actually one of /thousands/ of icy objects at the edge of our solar system in something known as the Kuiper Belt. think like the asteroid belt, but x200 and snowy. Pluto just happens to be on the inner edge and a liiiiil bigger and shinier than most of the others (this is also why it has the weird tilted oval orbit). However (after much hilarious and wildly innaccurate assumptions about its size), people thought it was the edge of our solar system for decades and everyone grew found of our little oddball “planet”
Enter Mike Brown, early ~2000s
our tech had gotten a lot better by that point and more of the Kuiper Belt was being discovered. a lot of it was small stuff or dust tho and no one wanted to redefine the word “planet” for a bunch of snow. Mike Brown was the astronomer who spent years searching for the next planet, during which he discovered several Kuiper Belt objects, like Sedna and Makemake (who’s named after an Easter Island god btws, stop all the comments on the name /oh my god). ANYWAYS none of the lil snowballs were quite big enough to justify overhauling the planet classification system at the time
But then came Eris.
This lil ice ball is juuuuuust about the size of Pluto (give or take 3%, we don’t have the means to find its mass exactly yet). This sent the entire community into a frenzy for several reasons: there were astronomers who had been arguing that our planet classification system needed to be redifined for ages. Planet only came about because the five we can see with our naked eye were the only objects that “wandered” through the heavens as far as people knew at the time and later on it just kinda, stuck. But as we discovered more about space, things like comets and asteroids and moons could also be called planets and the definition kept shifting until it eventually settled on “big, round, and doesn’t orbit another planet”. By this definition, we have hundreds of potential planets within the Kuiper Belt though. People were content to keep it since none of the objects at the time were bigger than Pluto tho
Eris changed that. What many people don’t realize is how *small* Pluto is. So some astronomers argued why cut off planets at such an aribitrary mass whereas others didn’t want to kick out everyone’s favorite oddball. There were *so many* heated debates and conferences on this (of which planets were almost reclassified in such a way that our moon would become a planet and Jupiter a moon (no, I am not joking)), but eventually it was settled that an object was a planet so long as it
-orbits the sun (✔️)
-is round (✔️)
-clears its neighborhood (❌)
Pluto fails the last classification and is how astronomers finally demoted it. It’s actually a much better system and a lot cleaner than many of the other suggested systems and will cause much less hassle down the line. They created the term “dwarf planet” as a consolation prize in an attempt to sooth everyone who was super salty about this tho, which is how the others got grouped together in it instead of just being called planetoids like they had been for decades (tho the five above are the only recognized dwarf planets from a list of hundreds)
Also, for everyone in the comments who was confused, Ceres is the largest asteroid in the asteroid belt. It was one of the solar system objects up for reclassification when everyone was trying to officially redefine “planet” and still keep Pluto around and that’s why it’s now known as a dwarf planet instead of just “that large rock with all the other rocks between Mars and Jupiter”
Im on my phone rn so no links atm, but I might (probably) add sources when I get back to my computer as I’m v passionate about these snowballs and space. But for everyone who wants to read about the tale of finding Eris from someone with an absolutely fantastic sense of humor, check out Mike Brown’s book “How I Killed Pluto and Why It Had It Coming.” The whole event is a ride start to finish and some of the most entertaining drama ever
ALSO fun fact: Eris was absolutely named after the Greek goddess of discord on purpose. I fucking love Mike Brown y’all
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