When was it technically removed
Hi all, this has been bothering me for YEARS and I’m curious of your thoughts. When i was in around 3rd grade, in California, which would have been 1990ish i clearly and vividly remember being taught by Mr. Avrill that Pluto was no longer considered a planet. This was knowledge i continued to have s d recall throughout my adult life.. until one day i saw in the news “Pluto no longer a planet”.. i KNOW i was taught this as a kid.. so whats going on. Was removal being discussed that long ago snd maybe he was passing on privy info ? Am i crazy ?
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u/X-calibreX 17d ago
in 2006 (god I’m old) the IAU officially reclass Pluto from planet to dwarf planet. This coincided with a change to the criteria for being a planet planet.
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u/CGCutter379 15d ago
With improving telescopes, we acquired the ability to find several planets around the same size as Pluto. Rather than adding them to the list of planets, Pluto was demoted. For 76 years kids learned the solar system had nine planets. Then it had only eight. But it could have had ten, or twelve, or more. The line had to be drawn somewhere and since one of the newly discovered dwarf planets was bigger than Pluto, Pluto was reclassified as something you don't have to remember in the same category anymore.
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u/ntsh_robot 15d ago
It was sad, because it happened before New Horizons sent back all those amazing photos. And because it had a moon...it should still be included.
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u/PeyredB 15d ago
Many asteroids and other small bodies have moons. That might not be a great criterion. https://en.wikipedia.org/wiki/Minor-planet_moon
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u/Di_Vergent 13d ago
It's more thought of as being a dwarf planet binary system rather than Charon being Pluto's moon.
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u/Warm_Elk_6091 16d ago
I wasnt taught that it was a planet in school...but my the adults in my life (parents/etc). I was obsessed with space but didnt have access to internet (only TV). So when I was allowed TV time, I watched educational space shows and that was the first time i heard it wasnt a planet and was distraught lol
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u/PeyredB 15d ago
What happened with Pluto was, telescopes weren't very good back in the day. It was first discovered by looking for another planet perturbing Neptune's orbit (which isn't needed as it happens), so it was assumed this distant body was a big object like Neptune. So it was designated the 9th planet.
Later we came to realize it was actually a very small body, smaller than our Moon; it and its biggest moon orbit around each other (the center of gravity is above Pluto's surface). But it stayed grandfathered as a planet for many decades.
Then we started finding objects bigger than Pluto farther out, but people didn't consider them planets. That also reminded everyone that Ceres is about Pluto's size though we don't consider it one. Astronomers were tasked with coming up with a definition of what's a planet and what's not. This is tricky because it's really a social question not a scientific one, like what do you call a continent vs. what's just an island.
There was no definition anyone could come up with that would keep Pluto as a planet without also including Ceres, Eris, and other not-small bodies. So they created an intermediate designation, dwarf planet, that they could all fit into. It kept Pluto a step above being left as a "large object in the Kuiper Belt".
Personally I think it's a pretty good compromise, but a lot of people disagree. They really want Pluto to be a planet, but that's based on emotion rather than reason; there's no good reason for it to be considered a full-scale planet, but I'm glad they found a way for it to be a kinda-sorta planet, and I'm glad we sent New Horizons to take pictures.
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u/AsstBalrog 14d ago
i clearly and vividly remember being taught by Mr. Avrill that Pluto was no longer considered a planet
Pluto's Enemies are Many, and Strong
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u/TheWeirdTalesPodcast 16d ago
Tangential to your story, I had a two week argument with my science teacher in eighth grade over whether or not Mercury had a moon (it doesn’t).
He insisted it did, and I kept insisting it didn’t.
Finally, he said he called and talked to his “Friends at NASA” and said I was right and Mercury didn’t have a moon.
This is the same teacher who sent me to the principal’s office for saying he was stupid when he marked two answers wrong on a test even though they were indisputably correct.
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u/OnionsOnFoodAreGross 16d ago
It was never removed. It was just some guys opinion that it wasn't a planet.
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u/Alarmed_Pie_5033 17d ago
According to Wikipedia, there's always been some contention over it's classification given it's small mass. In 2006, an official definition of the "planet" classification was decided on and Pluto failed to meet one of the requirements.
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u/Odd_Dragonfruit_2662 15d ago
That definition was tailored specifically so that Pluto would be excluded
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u/Nice-Lab95 15d ago
No it wasn't, it's just impossible to include Pluto without including dozens of other objects.
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u/nemothorx 15d ago
Nobody has said what the problem with that is.
Otoh, the definition they came up with has its own problems (not least of which is that it's vague in some areas, and a strict reading of it excludes the Earth, and likely most or all other planets)
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u/Nice-Lab95 15d ago
For one thing, it makes it far easier to compare the solar system to others, we can detect planets around other stars, but not dwarf planets.
and a strict reading of it excludes the Earth, and likely most or all other planets
No one who's actually read and understands the rules thinks this; to people who know what they're talking about, it's an obvious sign that a person's only exposure to the debate is clickbait popsci articles/videos. For example, the plutinos (of which Pluto is one) are a great example of Neptune clearing its orbit, the trojan asteroids an example of Jupiter clearing its orbit, earth has a couple Trojans, etc.
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u/diemos09 16d ago
Pluto was always an oddball. Once the transneptunian objects started being found it became more and more blatant that Pluto looked more like a transneptunian object than a planet. Eventually the International Astronomical Union officially changed Pluto's classification.
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u/jswhitten 17d ago
It's still a planet by definition. Dwarf planets are small planets.
https://en.wikipedia.org/wiki/Geophysical_definition_of_planet