4 ms·

> Your point is valid - we do need to classify things for our own mental convenience - but I don't think the Pluto case is an example of it. Obsessing over the

> Your point is valid - we do need to classify things for our own mental convenience - but I don't think the Pluto case is an example of it. Obsessing over the definition of "planet" to that degree doesn't actually achieve anything useful There are people who feel that it's worth classifying all the objects in our solar system and that doing so is useful. It's pretty much always been that way. The original definition of "planet" was used to classify things visible in the sky and the criteria was simply "stars that moved". The Sun and Moon were "planets". Asteroids were "planets". We've been constantly updating our classifications ever since as new information became available (see https://en.wikipedia.org/wiki/List_of_former_planets https://en.wikipedia.org/wiki/List_of_former_planets). Pluto was discovered in 1930 after a pair of photographs showed another light in the sky had moved. Until the 1990s we thought Pluto was alone out there at the edge of our solar system, but then we discovered 15760 Albion, followed by another new "planet" named (181708) 1993 FW followed by the discovery of hundreds of other tiny objects until it was realized that Pluto wasn't alone at all. There was a massive belt containing a vast number of small objects past Neptune and Pluto was just one of those small objects (see https://upload.wikimedia.org/wikipedia/commons/5/5b/Kuiper_belt_plot_objects_of_outer_solar_system.png?utm_source=en.wikipedia.org https://upload.wikimedia.org/wikipedia/commons/5/5b/Kuiper_b...). The discovery of a bunch of objects of similar size and composition to Pluto, Eris in particular, made it clear that Pluto just wasn't like the other planets in our system. We had 8 large planets that acted similarly and one tiny planet that was unlike the others because it was just part of a much larger system of smaller objects. It made perfect sense to refine our definition of what a planet was taking our new understanding into account. It's also reasonable that the job of doing that wouldn't fall to one person to decide on their own. The International Astronomical Union was already responsible for maintaining a set of astronomical naming conventions from the names of stars to the names of specific planetary features like craters. Since we wanted to have a standardized distinction between planets, moons, asteroids and comets and all the other objects in space who else do you think should do that? Having a committee of experts from all over the world seems as close to an ideal as you can get. As for the definition they settled on being "bad science", it was debated and voted on. There were alternatives proposed, but none of them won out. If somebody ever comes up with something that is clearly better, especially as we learn more about objects outside of our solar system, that option can also be considered and voted on. What other process should we have for those kinds of decisions?

antonvs 1mo ago
> There are people who feel that it's worth classifying all the objects in our solar system and that doing so is useful. Up to a point. Part of my point is that the specificity of the new definition of "planet" is a bit silly. It's completely arbitrary. It's certainly not uniquely correct in any sense. It's also a kind of post-hoc definition which assumes our specific Solar System. For example, let's say you had a rocky body, around the size of Mercury, that had a very eccentric orbit that only reached the Kuiper Belt every few hundred years, at its apoapsis. Would this object "clear its orbit"? Hard to say - the IAU definition isn't precise enough to answer this. The IAU definition is basically the answer to the question: how do we label the closest eight planets to the Sun as planets without saying that's what we're doing, because we don't want to have to add a whole bunch of KBOs to the list of planets? None of what the IAU did here constitutes anything resembling real science.

antonvs 1mo ago

> There are people who feel that it's worth classifying all the objects in our solar system and that doing so is useful. Up to a point. Part of my point is that the specificity of the new definition of "planet" is a bit silly. It's completely arbitrary. It's certainly not uniquely correct in any sense. It's also a kind of post-hoc definition which assumes our specific Solar System. For example, let's say you had a rocky body, around the size of Mercury, that had a very eccentric orbit that only reached the Kuiper Belt every few hundred years, at its apoapsis. Would this object "clear its orbit"? Hard to say - the IAU definition isn't precise enough to answer this. The IAU definition is basically the answer to the question: how do we label the closest eight planets to the Sun as planets without saying that's what we're doing, because we don't want to have to add a whole bunch of KBOs to the list of planets? None of what the IAU did here constitutes anything resembling real science.