I get it. This whole Pluto thing has been a confusing mess ever since the decision was made to demoted from planet to dwarf planet back in 2006. And people are still talking about it because it's kind of a big deal. I mean, I guess there's a lot of personal investment in the history of Pluto for many astronomers, but also it really gets down to like what is a planet? How do planets form? What does it mean for these objects? Like astronomers really, really care about classifying things because our classification helps us understand things or another way to put it is that by classifying objects, it represents our understanding of an object. And the better we can classify objects into different categories, the more we understand it because now we have a more refined understanding. I mean, like the case in point Pluto way back in like the 1800s, when we first started finding asteroids, they were counted as planets. And then we realized there was like a bajillion asteroids and no one wanted a bajillion planet. So they all got demoted down to asteroid with Pluto. And Pluto was discovered back in 1929 by Clyde Tombow found it. It was just like automatically assumed to be a planet because there aren't a lot of objects that are that big, they're capable of orbiting the Sun. Like so it was just assumed to be a planet. Yeah, it was weird, but you know, everyone has a weird member their family. So, you know, no big deal. But then in the 90s and early 2000s, we started finding more objects out there at the orbit of Pluto. And it looked like we are in a very similar asteroid situation. Like, oh my gosh, are we going to have 10,000 planets? And if we have 10,000 planets, yes, that's a lot to memorize. But also like if we have a single category that contains 10,000 objects, are we sure we understand that object? Like there are 300 billion stars in the Milky Way galaxy, but we know what a star is. It's something that that uses hydrogen in its core. So boom, star, that is something that can label every single object in this class, even though there are hundreds of billions of them. Both we have 10,000 planets. Is there something that we can define that makes sense that is able to accommodate all of these 10,000 members? Debate ensued. And then in 2006, there was a meeting and this is a very, this is a controversial decision. This whole thing about Pluto not being a planet anymore is not widely agreed upon or unanimously agreed upon. It was up for a vote. Back in 2006, at a meeting of the International Astronautical Union, I believe that meeting was in Hawaii. I mean, astronomers are really good at picking a meeting locations. But there were shenanigans like there were there was a proposal like, hey, by the way, maybe we should define the word planet and decide are there going to be a small number of planets? Are there going to be a large number of planets? Like how are we going to shape this definition? There was a proposal to adopt a definition of planet. But apparently this vote came on the very, very last day of the conference. And the International Astronautical Union, like anyone in any astronomy field can be a member. I've been a member. If you're a member, you're allowed to vote on this question of is Pluto a planet or not? But like I'm an astrophysicist. I'm a cosmologist. I don't study the solar system, but I would be given a vote on whether Pluto is a planet or not. Simply because I if I was a member at the time at 2006, I wasn't. But if I was as a cosmologist studying the universe, I would get a vote on this. I mean, okay, I find like I had no personal like knowledge of the situation yet. I would still get a vote. That's one thing. The vote came at the very, very last day. And apparently it was somewhat of a surprise like, hey, by the way, we should all vote. But all the sessions of that were the planetary scientists got to talk. Those were all held earlier in the conference. And so they all went home. They're like, oh, the last day that's just for like supernova people. We're not really interested. We got to go back to work. So many of them left. And we're even present on the last day. And then the last day of a conference is usually a big conference like that is usually half day, not like on on. People are especially in Hawaii. You're probably at the beaches not sitting around in the conference room. So there's shenanigans on that. It was a surprise announcement. It wasn't a part of the program. So like no one knew the vote was coming. And then there happened to be enough people that voted on this and then made it like established international astronomical union rules. Now the international astronomical union is not in charge of anything except I mean, they claim they're in charge of a lot of things. But really their authority is because everyone agrees that they're the authority. But so like the community of a stormers shifted to this definition in 2006. And there's been arguments ever since then. And then the definition of plan goes like this, one year with the sun. Okay, that's like literally everything that orbits the sun, including planets and comments and asteroids and micro meteoroids. Like there's not a very helpful criteria, but we'll start there. Two is it has to be large enough. The object in question has to be large enough that its own gravity makes it round. So this cuts out the asteroids, it cuts out the comments, it cuts out like rinky dinky moons. It's just you have to be big if you want to be a planet. But under this definition Pluto is included, but because Pluto is is round, it's big enough to be round. But then the third definition was explicitly designed to cut out Pluto from the definition of planet. And all of its friends too, because even under this definition with your orbit, the sun, you're big enough to be around, there'll be like 10,000 planets. People were uncomfortable with that for some reason. So they said, okay, where there's going to be a third definition in order to be a planet, you have to quote clear your orbit, which means you have to be the dominant player in your orbit. There can't be any other big junk in your orbit. You have to be in charge. In Pluto has a big moon called Sharon, and there's lots of junk out there in the outer solar system past the orbit of Neptune. So under this definition, Pluto gets cut out. And that gives us eight planets, and then a bunch of dwarf planets and minor planets, and then there's all these sub definitions that have cropped up since 2006. Okay, fair. Like if that's your definition, then Pluto doesn't make the cut. It's not a planet. Other people have argued against that idea. People who weren't there at the vote or who voted against it said, look, look, look, look, look, like you're creating a definition of planet, not based on an intrinsic property of the object itself, but on what's happening in its orbit. Like if you were to swap places, if you were to take Earth and put it in the orbit of Pluto, Earth would all of a sudden lose its status as a planet. If you were to take Pluto and put it in the orbit of Earth, Pluto would become a planet. Like that seems a little bit weird. Like it depends so carefully on where you are in your orbit, and who else is in your orbit. And also there's the argument that like if you look at a picture of Pluto, it looks like a planet. Like it's got cool geographical features. It's like warm on the inside. There's like nitrogen, glaciers, frozen nitrogen, glaciers, super cool. Looks like a planet. Like if you were just to show someone a picture of Pluto, they would say, yeah, looks like a planet, I guess. And that kind of intuitive understanding of what a planet looks like and X like and taste like and smells like should guide us in some sense. So the arguments go back and forth. Is Pluto a planet currently? It's defined to be a dwarf planet and not a full proper planet. We only have eight planets in the solar system. This is what generations of generation of kids ever since 2006 have been learning in their science classes. Could it change back? Yes, absolutely, because as we learn more about the other solar system, we can we might realize that like wow, Pluto isn't much different than say the Earth or Mercury. It's just small and really far out there. So yeah, it should be a planet or we may stick to this definition. There's so many arguments about it because we don't fully understand planet formation, planet dynamics, the structure of planets. Our categories, our classification schemes are shifting around because we are updating our understanding. It could very well be a hundred years from now. We do have 10,000 planets orbiting this sun because we've come to a better understanding. Or it could be a hundred years from now, there are only four planets in the solar system, just the big gassy ones. Like, who cares about these tiny little rocks close to the sun? Or it could be a hundred years from now, we stick to eight and we're answering other questions. If you want, here's my point. This is what the the International Astronomical Union says Pluto isn't a planet because of a vote they made in 2006 based on definition that none everyone agrees about. If you want to think of Pluto as a planet go right ahead, in fact, when planetary scientists start talking about Pluto, they kind of use the word planet already in their papers and in their presentations. So if you want Pluto to be a planet, just go on right ahead. I'm not going to stop you and please go to I won't stop you go from patreon.com slash pmsutter to keep this show going. 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