Is Pluto a Planet?

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You know what a planet is, right? A big round thing that orbits a star. Uh, not so fast. The surprisingly vicious debate over the planetary status of Pluto has given us a fascinating glimpse into what a scientific definition really is. And perhaps the word planet is too vague to be used as a scientific definition at all.
Hosted by Matt O'Dowd
Written by Drew Rosen and Matt O'Dowd
Graphics by Leonardo Scholzer
Directed by: Andrew Kornhaber
Produced By: Kornhaber Brown
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We love to classify things. Labels help us keep stuff organized in our heads. In science, categorization provides a fast and easy way to know the properties of a member of the group just by knowing what group it belongs to. Chemists group elements on the periodic table, those groups exhibit similar chemical behavior that reflect outer-shell electron number. Biologists group organisms by similar physical characteristics, and this taxonomy reflects genetic relationships. Astronomers are all about space taxonomy. We classify galaxies based on their shape, black holes based on how they feed, stars based on their colour and brightness, and planets by… well, by a set of criteria that has caused more tension and heartbreak than any made-up grouping scheme really should. Because a change in that scheme demoted Pluto from planet to not-planet. Today we’re going to settle whether this was reasonable, and whether we should keep the word “planet” at all.
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[@EldafoMadrengo397]

Around two years ago I found this channel, and was so engrossed that I promised I'd go back to education. Today I started my first day at university to do astrophysics. Thanks so much to Matt and the spacetime team for being such an inspiration! Keep up the good work!

[@DaleBEATBOX]

Im a year behind you but feel im falling down that rabbit whole too! I think you know when you pause and realize your jotting down geometric theorems and delving deep into algebraic equasions like never before just to sharpen the mind and prepare yourself for a higher education. :)

[@speedball1919]

I’d love to do the same but the math is just too scary for me. Good luck man!

[@IAMSTEVIERAYBITCH]

@@speedball1919 don't worry about the math it's all made up anyways! The fact is nobody has ever been to a star, touch the star Tasted a star, is able to manipulate a star, do I need to go on about how fake it is. Yes I know some people still believe in Santa Claus.

[@warwolf715]

Incredibly jealous! Have fun!

[@peeftribos]

If is in the internet it must me truth

[@xFirebird925x]

"We anthropomorphize everything" The single most important message from this video.

[@ajdefault01]

Yes, a scientific definition needn't have an anthropomorphic name tag like "dwarf". Why not micro/nano or something else more neutral? All of the inner planets are dwarfs compared to the gas giants.

[@anarchyantz1564]

Neil DeGrasse Tyson was right to kick off the request to getting Pluto stripped of its term. They should all just keep them named as asteroids rather than Dwarf Planet as its still then a "planet"

[@karlkutac1800]

Matt's comment on Pluto's "feelings" about be reclassified reminded me of a joke I once saw - "Don't anthropomorphize computers .. they hate it when you do that."

[@srpenguinbr]

When I was a kid, I asked someone why Pluto was not a planet anymore and they replied it didn't exist anymore because it had exploded I believed this for a while lol

[@stephenbrand5661]

If you’re that young then you’re still a kid

[@dontbotherreading]

For me one day I was in school and there was actually an announcement made on the PA system telling everyone about the de-planetary status

[@Pyxis10]

@@stephenbrand5661 And you're a jerk.

[@rx7racerca]

It was your dad who told you that, wasn't it? Total dad-joke move. Said as a dad.

[@secretagent0280]

@@stephenbrand5661 No. It stopped being called a planet when I was a kid as well.

[@Byronjesk6004]

Most pbs spacetimes = way over my head This pbs spacetime = more my speed

[@Kevin_Street]

I love all of them. The ones that are over my head are a lot harder to understand, but that's not a bad thing. The moment of realization when everything finally makes sense is awesome.

[@AgentJRock805]

right there with you!

[@theconstantchange]

@@Kevin_Street that's so true. It's the realization of it. It's not the destination it's the journey....

[@Skylancer727]

Then you go back to their videos of before the big bang and inflation and realize you're way behind the curve when they bring up the inflaton field and scalar fields. XD

[@zeon_zaku]

I have a physics degree, and they even fly over my head. :p

[@raneemacintosh6842]

I particularly enjoy the fact that this video about Pluto not being a planet was uploaded on Neptune's birthday. 'Who's the furthest planet now!?'

[@backpacker3421]

I'm quite certain you mean the anniversary of its discovery.

[@raneemacintosh6842]

No he didn't exist til the guy that wasn't William hershel found him, Big Blue himself, on 09.23.1846. Just like how your birthday is the day your mom discovered that a baby came out of her.

[@Enourmousletters]

@@backpacker3421 No. He meant its birthday.

[@backpacker3421]

I love how many people rushed to defend the notion that planets have birthdays, on a science based educational channel. You guys sure showed me.

[@Enourmousletters]

@@backpacker3421 all planets *do* have birthdays

[@arborinfelix]

Can't we just give Pluto a life time achievement award, just to say that "you didn't make the list but we still love you"

[@EnderCrypt]

pluto: an honorary planet

[@d.sm.4146]

Astronomical Participation Trophy?

[@dhardy9296]

Pluto's like.. "I'm 4.6 Billion years old, do I care what you puny humans call me."

[@rickrobitaille8809]

Thank you...

[@MrToastercide]

Also Pluto.. Whilst I dont officially care, referring to me as anything but a god or a planet will incur my icy wrath

[@tavusion]

We don't even know what its parents named it, so its like: Who's this Pluto kid? I'm ê8%0fji#2 Jr.

[@pierfrancescopeperoni]

Even assuming plants think, big objects think slower (because the information needs more time to pass from one point to the other), so he perceives less time.

[@tiretalks]

@@LucasFerreira-gx9yh qee re the tree tree tree a tree tree tree tree tree q r r ah ah em he Tom he tho he a add he at ya tho is ah he asks as gd a a a

[@ZappaBlues]

I hope the planet club still occasionally allows Pluto in for drink.

[@lonestarr1490]

Pluto yes, but not Earth. Because Earth has homo sapiens and that might be contagious. It's not a permant ban, though.

[@ZappaBlues]

@@lonestarr1490 Jupiter to Earth, "Well little sister, I see you still have those pesky little parasites scurrying around on your surface. I could a send comet or meteor or two your way. That should help"

[@robinchesterfield42]

I mean, it's not as if it's not old enough to drink. It's over 4.5 billion! :P

[@MarkHobbes]

What about Ceres, Haumea, Makemake and Eris... It's not only Pluto the dwarf planet

[@FutureDeep]

Pour one out for Pluto.

[@SoleaGalilei]

As a linguist, I would add that scientific definitions of words aren't always strictly adhered to among laypeople, who may have very different priorities in what and how they're communicating. I can easily see "planet" becoming one of the many, many words that has both technical and nontechnical senses. If "thing that goes around the sun" is a useful sense of the word for nonprofessionals, they will probably continue to use it no matter what authority figures have to say about it. Historically, such tends to be the case. Thanks for the video and for highlighting the changing usage of the word! Finally, a Space Time video that relates to my field. :)

[@RedRocket4000]

We can get them to learn round and goes around the Sun

[@K1lostream]

If you're a linguist can you explain why so many people use the word 'literally' when they absolutely do not mean literally?! i.e. 'That Ricky Gervais show was soooo funny; I was literally pissing myself laughing'!

[@BrittneyLynne]

@@K1lostream As a linguist, I can weigh in on this. Words shift meanings or add definitions all the time (semantics is a field of study in linguistics devoted to studying these changes and why they occur). For over 300 years (at least since 1760), "literally" has had a second meaning as an intensifier/a synonym for "completely, utterly, absolutely" and honestly, it's probably used more in the second definition than the first that some people get all up in arms about. "Literally" is a perfect example of a semantic phenomenon called hyperbole, which is the changing of a word due to exaggeration or overstatement. It is also an example of a word that has an opposing definition of the original one. There are many words like this in the English language, but literally began to undergo this shift far more recently than other examples (awful, bully, artificial, villain, harlot, resentment, and egregious, to name a few) so both of the definitions are still in use, which is what causes the contention.

[@K1lostream]

Brittney Koza Thanks for the reply! In that case I must say I find the wilful misuse of the word 'literally' an awfully egregious transgression!

[@fuzzblightyear145]

then you can imagine our pain trying to explain a scientist's definition of "theory" compared to the general definition of the word.

[@kainotachi]

Don't think of it as Pluto getting demoted, but as Pluto finding a new group of friends that it has more in common with, and thus gets along with much better.

[@rafaelsierra7287]

That whole video sounds like "NO" with extra steps

[@jasonpatterson8091]

9:33 I'm beginning to think that you're not really floating in deep space...

[@Random3r]

how?

[@SamBellows]

@@Random3r minor clipping when he doe his air quotes, half his hand goes away. Jason has a scary good eye. :D

[@fvckyoutubescensorshipandt2718]

I though that was obvious from day 1. It's a green screen like everything else not made by a 5yo in the past 30 years.

[@koolkyle1420]

WomenAreJust DumpstersForBabyGravy its a joke

[@r011ing_thunder6]

He has no legs... like the Swede

[@kylehazachode]

I like how Star Trek designates planets by a class type. Pluto is a class C planet, Earth is a class M. If we do it like that then it can cut down on the bickering.

[@liamscienceguy8153]

I highly agree. If it looks like a planet, it’s A planet!

[@drjojo5551]

star trek huh??? are you an infant??

[@vladdrakul7851]

@@drjojo5551 Are you stupid?? Star Trek was founded by a NASA scientist (Gene Roddenbury) It even had scientists helping with the shows ideas on future technologies and is one of the very few intelligent thoughtful philosophical shows out there, designed for thinking people which I guess excludes you.

[@EvenTheDogAgrees]

@@drjojo5551 Lol, i once heard someone describe Star Wars as "Star Trek for kids". Can't say I agree; Star Wars is Star Wars, its own thing... Star Trek on the other hand is very much Star Trek for kids. Don't get me wrong, I enjoy the shows, but if we drop the fanboyism for a minute, we can all agree that Star Trek is far from intellectual. If you want to escape the kiddy realm, try some hard sci-fi instead. 😉

[@vladdrakul7851]

@@EvenTheDogAgrees Star Trek is MUCH more grown up than Star Wars. At least the original and new DIsney Star Wars are (goodies vs baddies in space) although the wrongly maligned 'Pre quels' are actually much the most grown up version of Star Wars (and very underrated by the MSM who LOVE shallow and immature). Star Trek was always about both scientific and human issues rather like DR Who in its better ears (Dr's # 1-4 and Russell Davis's 9 and 10.

[@Sonimod]

Jerry Smith: "They called me a madman"

[@user-us6jv4zp6d]

Bumbum granada

[@DavesCoverSongs]

I dozed and woke up at 15:55 to him saying “DAVID!” over and over. Kind of freaked my out. 😂

[@stefantheconqueror8710]

I didn't hear a single David in there

[@DavesCoverSongs]

StefannoTheConqueror holy cow! You’re right. It must have been a ‘quarantine dream’. That’s really weird.

[@epsilonjay4123]

Why does everyone argue over this. Either way, Pluto is interesting. Cryovolcanoes, Nitrogen Ice, Tholins, five moons. Either way, it's a cool object.

[@markchapman6800]

... a "moon" (Charon) that is far closer in size to it than any other moon to its parent in the Solar system (and is bigger than Ceres, which I didn't know until now), and that Pluto is tidally locked to, as well as it being tidally locked to Pluto. en.wikipedia.org/wiki/Charon_(moon)#Classification

[@JonesP77]

Because humans are very emotional and minimal to non-logical animals! ^^ I also felt sad (for whatever reason, probably because i learned that it was the 9th planetas a child) as i learned that we now only have 8 planets. But i could accept it pretty fast because the arguments are very good and it makes a lot sense, unless someone wants to have 100 to 1000 planets... We have to give the other humans some time to get over it. In 20 years everybody can accept the fact.

[@terrypeart3875]

Epsilon Jay ɛɈ ⸋ Ȣ ƪ ϡ ϧ Ϯ ϗ ƕ ⸈ “So, now I’m an object”

[@leavy]

is feeling nothing when Pluto was declassified a sign of psychopathy or sanity?

[@JelaniWood]

"Pluto can be a cold, cold celestial dwarf..."

[@gibranhenriquedesouza2843]

In my opinion we should collide all the Kuiper Belt objects and create a new big ice planet.

[@zemoxian]

Actually, for living space and access to resources they’re better as they are. Maybe just bring them in closer for easier access. Just not too close. Don’t want all the volatiles of a hundred giant comets losing their surfaces all at once. Then again, that would make an amazing night sky.

[@Bitchslapper316]

Sounds like an easy plan

[@ansh6370]

There are 35,000 objects in the Kuiper belt that have more than 100 km diameter, so an average mass of such objects is 5×10^14kg Multiply mass by the number of objects and you make an object of a mass of 1.75e19kg (This figure may change as there could be more objects out there and the mass of such objects vary, this is just a fairly accurate estimate), which is only slightly more massive than Pluto. So, you can't create a whole planet with just the objects in Kuiper belt.

[@Bitchslapper316]

To simplify, the entire kuiper belt has an estimated mass of 1 - 10th to 1-25th the mass of earth. Not nearly enough for a planet like earth or bigger.

[@InanisNihil]

while we waste time of doing that.. life on earth dies cause green house gas went overdrive..

[@rayjulien4739]

I feel for Pluto. I mean try as I might...I can't clear my garden of weeds!

[@Harkeilla]

Piss on your garden for a week in the same spot. The chemicals and salts in your piss naturally break DO n the fertilisation of the soil, so you'll not have to worry about weeds growing there anymore.

[@skirwan78]

Beautifully bridges the gap between emotions, objective reality, complex mathematics, and intuitive explanation in a way that would make Cal Sagan proud. Excellent video, cheers!

[@tamatebako_yt]

Right?! I enjoy the synergy quite a lot. "That's the beauty of the scientific process." Damn right it is!

[@sclair2854]

If we ever do find Planet 9 we should just call it Hades and pretend all the old textbooks were just using the Roman name

[@aredjayc2858]

I like this idea

[@lamebubblesflysohigh]

or copy what people in online games do and call it xXxPlut0xXx :D

[@dangerous_safety]

I've always preferred Persephone myself. The wife of Pluto with a wintery theme, both in reference to the extreme distance and eccentricity, but also of the passage of time, and the shift from Pluto to Persephone as the 9th planet. It keeps the theme of naming TNOs mostly after feminine figures and aligns with the name of an additional planet used by Arthur C. Clarke and Larry Niven.

[@sclair2854]

@@dangerous_safety Thats also a pretty good one. Though if I were to go with a feminine name I'd probably pick Nyx for the perpetual night type deal

[@DANGJOS]

@@sclair2854 That's already the name of one of Pluto's moons, isn't it?

[@hereLiesThisTroper]

Pluto is not a failed planet, it's just an over ambitious Dwarf Planet.

[@robertt9342]

Overgrown comet?

[@SylkaChan]

That's right. It's a dwarf planet, so it's a planet much like the way a white dwarf is a star (not red dwarf because they're too significant).

[@pleasedontshootofficerihav4953]

Its a large asteroid, mostly ice.

[@VajiraLasantha]

Neil with it...

[@Blackatchaproduction]

Lol

[@nexusvoid314]

This is a beautiful analysis of how vague definitions can cause confusion in science.

[@ccvcharger]

Now, if only we could figure out a solid definition for "life" that won't be thrown in the gutter every time we discover a new bacteria.

[@jcookepaleo]

Saw the title and i was like "Ah maybe i'll be able to keep up with this one"

[@RichardDunbar]

Looks like Jerry Smith’s position on this issue was dwarfed by more precise scientific classifications

[@PalaeoJoe]

It looks like Eris caused a little bit of chaos

[@BeethovenIsGrumpyCat]

DURR HURR

[@DB-xp9px]

I love the tongue-in-cheek sarcasm he uses talking about what could go wrong at the end of the video. Hilarious!

[@MrDirtydisco]

How does one get to become a very intelligent Scientist and such a well articulated host at the same time ? Good job Matt, you do amazing work.

[@oocalhoun722]

Dude, your hand slips into an alternate dimension at 9:33 -- I'm concerned, but also intrigued.

[@AlejandroW90]

O Ocalhoun green screen

[@oocalhoun722]

@@AlejandroW90 Are you suggesting that he isn't actually floating around the cosmos while making these videos?

[@drjojo5551]

i'm telling you.....he's on some BAD shit!!

[@notsoclearsky]

He mistakenly re-accessed the time machine he came here in.

[@ccvcharger]

So, I'm not the only one who saw that?

[@joenrowledge8172]

My biggest gripe with saying "Pluto is not a planet" is that the syntax very obviously suggests that "dwarf planet" is a KIND of planet, not a category of its own. It's not even slightly ambiguous. Either change the name, or stop correcting me! I know that science basically uses its own version of English that has its own rules-and that's fine, there's good reason for it. But when pedants like NDT get uppity about their usage being what's "correct," when in vernacular english it's explicitly INcorrect, well... let's just say it doesn't actually help with the whole "science communication" thing.

[@alexdaland]

What about an asteroid, should we also call that a planet? As the clip explains, then we would have hundreds of planets. So scientists do have to make different words for different things. A truck is technically also a car, would still be considered wrong to see a huge truck along the road and say "hey, that's a big car". That's how language, which technically are sounds put in order, is made. But it's easier to call it a language and words. When does words becomes a song? You see where we will run into problems if you, me, and every other random persons make our own categories or words? :) I think we are better off letting the people who works with the solar system decide

[@joenrowledge8172]

​@@alexdaland I didn't say that I disagreed with the definition of the category, I was specifically talking about the name and how it relates to the effectiveness of science education for the general public. Please re-read my comment carefully and try again. Also, the position you're advancing is called Linguistic Prescriptivism, and you should know that it's considered more or less entirely heterodox by people who actually study language. But hey, maybe we should just send everyone else home and let astrophysicists run every discipline. After all, they work with the solar system!

[@MichaelGraham1980]

Is soy milk a type of milk? Is beyond beef a type of beef? Boston cream pie a pie? Jellyfish a fish? Guinea pigs pigs? I’m sure you get the point. Having something named in reference to something else rather than a subcategory is pretty common and is hardly “incorrect”.

[@davidmcgill1000]

Everyone is so obsessed over classification. What does it matter what they are classified? Titan is bigger than Mercury but you don't see people lobbying to name it a planet just because it's orbiting the wrong object.

[@GraniteStateVictoria]

@@alexdaland There's a reason asteroids aren't planets, they don't meet the basic qualifications for a planet (spherical shape, stable orbit, the dominant player in their orbit). The "clears its neighborhood" is kind of vague, Earth's neighborhood isn't pristine, it's really just so we don't have too many planets, which is unscientific. A better solution is to put dwarf planets in as a third category of planet, very distinct from the other two, they can be the "marsupials" of planets, still planets, but very different. The astronomer who coined the term "dwarf planet" actually intended for it to be a third category of planet, not a category of small solar system bodies. One could also make an argument that red dwarf stars aren't actually stars but a category of rogue planet (a flimsy pseudoscientific at best, unscientific at worst argument, but nonetheless an argument). A better truck to car analogy would be regular planets are large tractor-trailers (big rigs), dwarf planets are box trucks, small solar system bodies (the asteroids you're thinking of for example) are passenger vehicles like personal pickup trucks and cars. A pickup truck is used as a car by most people, it has things in common with larger trucks, but there's a reason the road signs that say "trucks must take the offramp" don't apply that to pickup trucks. A pickup truck would be like Juno, Pallas, or Vesta, very much not a planet but distinct from a tiny hunk of rock the size of the Great Pyramid. Tractor-trailers and box trucks are very different from each other but are most certainly not passenger vehicles. I know I'm replying to an ancient comment, but I just wanted to share a different perspective.

[@jorvag]

I first heard: "We're launching a space time disco". alas...

[@MageToad]

NASA: "If it *can* be a planet, it can be a planet again. Planet. Planet, Planet, Planet." Rick: "Stay scientific, Jerry"

[@KanedaSyndrome]

Yes, Pluto is a planet, in my opinion.

[@PixelOverload]

I've long been of the opinion we should probably just redefine "planet" (yet again, but hopefully "finally", at least until something completely breaks it in the future) to simply "any celestial body capable of maintaining a spheroid shape" and then order & classify them based on their orbital nature and physical properties (two separate systems). For example (as i'm sure i didn't explain that very well): Orbital Order (the simpler part); - "Core" Planets: usually stars (or black holes), potentially brown dwarfs, that sit in the "center" or _core_ of a complex orbital system - "Major/Dominant" Planets: mostly the current accepted definition, planets that dominate their particular orbit around a core - "Minor/Dwarf" Planets: Pluto/Ceres/etc types that typically reside in "belts", sharing their orbit with other dwarfs and/or large groups of non-spheroid space rocks/"junk"/etc - "2nd Order" Planets: aka moons, basically, if the planet orbits a Major or Minor planet rather than orbiting the system core directly (probably needs a better name) - "Rogue/Wandering" Planets: any planet, whatever it's "Class" (see below) which is not part of a complex orbital system, drifting through space on it's own (possibly with some moons/2OPs, distinction from "cores" may be fuzzy*) In the case of binary/trinary/etc systems, i'd propose that if the center of mass lies within one of the bodies that one would be the core (and the other(s) probably major planets), while if it's located in the space between the bodies they both/all count as cores (this also applies to Major & Minor planets). This could be extrapolated such that (for example) if two stars act as a binary core while a third orbits both of them, that third would be the first orbital major planet, if the system is _too_ complicated to be reasonably broken down in this manner it's probably more useful to refer to it as a "cluster". * I'm tempted to identify any system lacking 2OPs or Minor planets as rogues (or "simple" systems), even if it's a star with one or two other planets orbiting it, but we currently lack enough data on how common/uncommon exomoons/exodwarfs are in other solar systems to really form a solid opinion on this yet as technically most if not all currently known systems (other than home) would be "rogues" based on purely empirical evidence, which seems a bit silly. But considering how abundant these bodies are in our system it's not unreasonable to assume most other systems have at least a few, so it probably shouldn't be a problem. The physical class system would essentially be how we currently distinguish between "rocky" planets, gaseous planets, brown dwarfs, stars, etc, with further sub-classification based on particular atmospheric or chemical composition, mass, size, quantum behaviour (ie: neutron stars and black holes, not that moon from outer wilds, lol), etc. I haven't really fleshed any of this part out thoroughly, or even really tried, as i personally lack enough knowledge on the subject to do so meaningfully. The currently used definitions are probably far better than anything i could come up with and will no doubt develop with time as we learn more about the bodies in and outside our home system. My main intention is to fully separate the concepts of orbital structures of a system from the physical structures of the bodies in that system as while there may be many modes between the two (ie: cores are usually stars, moons are usually rocky, gas giants probably usually have larger orbits), they obviously don't map out perfectly to each other in all cases and i think some people just get too hung up on that. Pluto, Mercury, and Luna may all be superficially similar in physical structure, but the structure of their orbits are vastly different, Titan may be larger than Mercury, but Titan's orbit has far more in common with Luna which is even smaller. Stars may be drastically different from gas giants, but if brown dwarfs blur the line, why draw a line? Full disclosure, i'm obviously not an astrophysicist, or a scientist of any kind, i certainly don't think this idea is complete or "rock solid" so to say, i've probably messed up a lot of jargon (i always do), and i haven't had much sleep so i'm prob a bit rambly. I just obsess over optimizing alternatives for organizing things and studying stuff that interests me whenever i can until the migraine kicks in and this is basically what i've come up with that makes the most sense to me. Probably overlooked some oddities or missed something obvious but i feel it's at least a decent starting point for anyone knowledgeable enough on the subject to improve if their interested. damnit, now my sammich is cold

[@PixelOverload]

@Cameron Smith good point, there's a lot of room for improving the terminology to reduce confusion and ambiguity, they're mostly just placeholders at this point, always been rubbish at naming things

[@sean_silvers]

I use to work at Lowell Observatory for a few years! We would sometimes give basically this video in an hour long talk. Little but more history on Tombaugh and his struggles with the blink comparator and the astrograph. But it had the same conclusion as yours, it’s just a ball of rock and ice, doesn’t matter what we call it, as long as that naming system is useful. Excellent video, also thanks for bringing up my boi VM Slipher.

[@chriso3130]

This is amazing! It satisfies all my reservations about the declassification of Pluto.

[@thebern3203]

Those who in 2006 said that "Pluto is not a planet" were being disingenuous for the sake of media attention *cough--NEIL DEGRASSE TYSON.* A Dwarf planet is a smaller planet. If it weren't a dwarf planet, then it wouldn't be a planet. If it is a dwarf planet, it is indeed a category of planet

[@dillmo28]

you are just jealous because Pluto is bigger than you

[@duoduopoi]

so true

[@atmclick]

Low blow, Dillmo. Low blow :)

[@theirishasian5490]

Nice

[@DuttonWebb]

You know what Pluto ISN'T larger than? ( ͡° ͜ʖ ͡°)

[@tompatterson1548]

But it wouldn’t fit

[@mikep8071]

Wait...there are THOUSANDS of objects the size of Eris and Pluto in our Solar System? O__O That really puts the size of our Solar System in perspective.

[@martingrundy5475]

It does when you realise that the Sun is over ninety nine percent of everything in the solar system. The current bun even makes Jupiter seem insignificant. However the actual distances between objects take another leap entirely. As does realising how big the Oort cloud is. And then the size of our solar system as classified where the bow shock gives way to true interplanetary space. Shit is BIG, Very BIG indeed, and even more well separated. Something many people do not realise and absolutely do not grasp. Especially the Alien/UFO cranks and flakes.

[@joebykaeby]

I’m not sure “it’ll be hard for kids to remember their names” is a good criteria for definition

[@GirtonOramsay]

"Think of the childreennn!"

[@DrWhom]

the singular is criterion

[@shikhanshu]

I didn’t expect to enjoy this video/topic as much as I did. Loved it!

[@jormungandr2376]

Pluto might not be a planet, but it'll always be and remain the 9th planet in my heart.

[@Merennulli]

You might want to talk to a cardiologist if you've got planets in your heart. That can't be good for your circulation.

[@sdfkjgh]

That sounds like an SCP.

[@davidfowler7040]

I remember when I was a freshman in high school. This was back in '54. I selected physiography as an elective, not really knowing exactly what it was. We had a test and one of the questions was "How many planets are there in the Solar System?". I put down 9 as my answer and the teacher counted it as wrong because our textbook (printed in 1928) said there were 8. I pointed out that Pluto was discovered a couple of years after the book was printed. The teacher said that she knew that, but we had to use the information from our text book even if it was wrong. I immediately dropped that class and switched to General Science, which was 8th grade science repeated, mainly. It pretty much cut me to the bone when planet-hood was taken away from Pluto making that old bitch and her out dated book correct.

[@bttrickk787]

Same

[@Merennulli]

@@davidfowler7040 Ugh. I had an antiteacher like that in my MBA program. She was completely incompetent in the course material and insisted we use the book even though I gave her references in my answer to show it was wrong. I took to writing things like "despite the fact that X, Y and Z, the book insists the fantasy that..." so I gave her answer while being quite blunt about it being wrong. Seems my being a jerk about it helped, though, as she got upset at our class for slamming her on the exit review for not showing up to class a full third of the time, nor knowing the material, and she gave people who didn't specify that their answer came from the book a 0 on the last assignment for "plagiarism". (Ours was an accelerated program, so we didn't have the option to drop classes.)

[@away69]

The greenscreen guy needs a demotion to dwarf-greenscreen guy...

[@Sciolist]

From 14:00 onwards I can see a giant meowing cosmic cat in the background.

[@mikejohnstonbob935]

Matthew hasn't cleared the neighborhood around his orbit

[@Cresanova]

@@mikejohnstonbob935 Nice

[@CylonDorado]

Nonsense, he should be promoted to Omega Green Screen Guy.

[@catoleg]

@@mikejohnstonbob935 He is not that massive to do so

[@shawnlorenzana2359]

Mike, your ability to communicate these subjects to laymen is phenomenal. Your articulation is impeccable. The jokes you throw in adds to your presentation well. I salute thee. The work you do here deserves elevation.

[@danguee1]

Who's Mike?

[@FrankCosbyNo-Relation]

So they decided to not call Pluto a planet because 6 year olds can't remember all the new discoveries 😑

[@joed180]

Only a hundred! Yea, kids are dumb.

[@gildedbear5355]

I know what a planet is. It's any of those planet looking things EXCEPT Pluto. Ceres and Erris are in but Pluto is out. More seriously, while I agree with The IAU's choice to classify the worlds in the Solar System such that Pluto is grouped with the other "smaller" things I disagree with their choice of words. It is a linguistic disagreement. A dwarf human is still a human, a dwarf horse is still a horse, a dwarf tree is still a tree, a dwarf star is still a star (expect for brown dwarfs but... they are weird but notably they aren't usually called "brown dwarf stars" so it gets a slight pass), therefore a dwarf planet should still be a planet. That is how the adjective 'dwarf' works. In my opinion they should have defined three terms. Planet: a body orbiting a star in hydro-static equilibrium (the same definition that it currently has sans clearing orbit). Dwarf Planet: a planet that has not cleared its orbit. and Major Planet: a planet that has cleared its orbit. (Minor planet could be a synonym for dwarf planet.) Then we simply teach children about the major and some of the more interesting minor planets (pluto, charon, ceres, vesta, ect) and everybody can be happy and nobody can say "but pluto isn't a planet anymore. This scheme also allows for easy expansion. We can have gas giant planets, ice giant planets, rocky giant planets. it'd be great.

[@samwisegamgee6532]

Your classification is very interesting, it’s simple and making planet a super category of astronomical objects could be useful. That would made 2 main categories of objects : Stars, objects which have started nuclear reactions because of their mass and Planets, objects which haven’t started nucleosynthesis orbiting around Stars. But of course science is tricky : what about interstellar objects such as oumuamua ?

[@franjojosip9800]

Scholz's star? It already visited and it's going to visit again. Gildedbear your idea is great. But I think if we have to clean the mess about planets, we also have to clear the mess around stars. Dwarf planets= not planets Dwarf star= stars What?!

[@jorgepeterbarton]

Pluto can't even compete with its own moon. Its own moon is bidding for swarf planet status. Its a dual system. F*** Pluto!

[@lordgarion514]

@@franjojosip9800 A "planet" is an object that meets all 3 requirements. A "dwarf planet" is an object that only meets 2 of the 3. I don't really see how adding extra words does a damn thing. Pluto is a dwarf planet, not a "full" planet. Adding major, minor, whatever to it changes nothing. And if one reads the actual IAU definition of the word's they're using, they'll see that a planet is a "celestial object" that meets 3 out of 3. A dwarf planet is a *celestial object* that meets 2, but doesn't clear its orbit. Nowhere does it say Pluto isn't a planet, but Pluto is not a regular planet. It is a *dwarf planet* . It boggles my mind that so many people have so much trouble comprehending something so simple.

[@lordgarion514]

@@davidperrier6149 Oh yes it is. And BTW, "cleared its orbit" in no way ever meant that not a single thing could be in its orbital path. By that definition there's no such thing as a planet as jupiter hasn't even done that. If you had actually spent some time on the IAU site, you'd realize that it means it dominates its area (massively). You can't have a completely clear orbital path for the simple reason that shit keeps coming in from outside the orbital path. So they obviously wouldn't use the word to mean something that they know for a fact is an impossibility. Earth is a planet, Pluto is a dwarf planet.

[@TheExoplanetsChannel]

Pluto will always be *in our hearts*

[@unf3z4nt]

I always rolled my eyes on Pluto. Even before reclassification, Pluto did not look too interesting bar that cack handed orbit.

[@Moses_VII]

Not me. I was too young when they made Pluto a dwarf planet! Pluto sucks!

[@cherrydragon3120]

I always liked pluto :D

[@randymotter51]

...pretty sure that Pluto will always be in orbit around the Sun, our hearts don't have enough space for it.

[@MattJasa]

I'll still love you Pluto!

[@Axle1324]

I love this channel. I always learn so much about Space.

[@TheExoplanetsChannel]

One day, Pluto might serve as a *space dock* for manned interstellar trips.

[@knyghtryder3599]

Cant wait

[@johntracy72]

It does serve as a stop over in the 1979 anime Galaxy Express 999.

[@jamesdriscoll9405]

Also a great spot for an antenna array & data relay.

[@rafaeldiaz2829]

Is Pluto a Planet? Neil deGrasse Tyson has entered the chat.

[@franjojosip9800]

Sheldon Cooper has entered the chat as well

[@Blake4014]

Jerry Smith has entered the chat too... he says its a planet!

[@chrisn4315]

Pluto itself... won't join the chat.

[@lncerante]

@plutokiller has entered the chat

[@matthewyabsley]

Pluto left the chat.

[@JasonRainwater]

One of the best videos I've seen in explaining the political matters revolving around the fuss of Pluto's planetary status! Though, in all honesty, there's nothing really to fuss about. Pluto is still referred to as a planet, it's just in a different category of planets now. A more fitting category. So it's rather disappointing people are worked up over this. Apparently, humans have the tendency to really get attached to labels and titles. A dwarf planet is still a planet, and Pluto remains a fascinating one at that. Nothing at all to get upset over. Thank you, PBS Space Time, for creating such great video on this topic! :)

[@TonyP9279]

It's important to know that Pluto was once considered a planet as there are many movies and literature around that references Pluto and/or 9 planets. The movie "Epoch" , for example, references nine planets and their locations were required to unlock the ship's door.

[@jeffcoutant8142]

Pluto is my favorite Disney Dog

[@imageignition23]

At around 10:15 you lose a few fingers with those "air quotes"... Careful with that.

[@fernandoroque]

@Manuel Sacha hahahaha i was thinking the same

[@anthonyward8853]

And at 9:33. Sloppy editing.

[@kikivoorburg]

I’d say the best compromise is just to divide the term “Planet” into 3 (or more): 1. Rocky Planets (e.g. Earth) 2. Gas Giants (e.g. Saturn) 3. Dwarf Planets (e.g Pluto) Then the definition for planet could be changed to simply “(somewhat) round object that orbits a star” (instead of just the Sun since that doesn’t count exoplanets). This way, schools can teach students the 4 Rocky Planets, 4 Gas Giants, and then explain that are far too many Dwarf Planets to memorise, but that Pluto and (to a lesser extent) Ceres are the most well known ones.

[@altrag]

That kind of fails outside of our solar system though, where we've found "super earths" that are rocky but much larger than our own Earth (though I don't think any come close to the size of even Uranus and Neptune, never mind Jupiter.) But we've also found gaseous planets that are much smaller than the giants of our own solar system (though again, I'm not sure if they come anywhere near as small as Earth.) So we end up with kind of a planetary spectrum. Which is hardly surprising when you think about it. Nature is pretty bad at generating the kind of black-and-white divisions that us humans tend to prefer with our arbitrary categorizations. And that's why the current definition is _reasonably_ (but not perfectly) good: 1) "Orbits around its star" _is_ pretty close to a black-and-white delineation. It either orbits the star, or it orbits something else. I mean its certainly plausible that a planet happens to do like a figure-8 orbit between a star and another body that's also orbiting the star. That would certainly muddle the definition. But I suspect those kind of orbits would be highly unstable and therefore very rare. (Of course there's also "rogue planets" which don't fit the definition of a planet at all because they don't orbit anything!) 2) "Is almost perfectly round" is a little more ambiguous. Of course the full definition gets more sciencey, but even then its not _as_ clear-cut as one would like to see (and more to the point, its not as measurable from a distance.) Some sort of cut-off measure for "roundness" based on observable shape -- ie: its geometry rather than its composition -- would likely have been a better plan IMO (I'm pretty sure such measures exist but the name isn't coming to me at the moment.) 3) "Has cleared its orbit." This is probably the most ambiguous one, mostly because its time-based on scales far longer than we can possibly observe. Does it count if the orbit is say, 50% cleared? Do we make the assumption that the wannabe-planet is going to finish the job and therefore give it full planet status? Or do we only count it as a full planet once the job is done? And going interstellar again, how do we even measure this with regard to distance planets? We're still barely able to notice things in the super earth scale. Observing asteroid/Kuiper-belt analogues is likely at least a couple of telescope generations ahead of us, if its even possible at all (there are fundamental limits based on telescope size, no matter how well the mirrors are polished or how amazing the electronic controls and analytic capabilities, and while we're probably not at the peak of telescope size we're likely getting close -- practical concerns like land area usage and construction cost will limit us eventually.) Anyway, none of that really matters since I wasn't and likely never will be consulted when these kind of definitions are made. Just my personal opinion on them.

[@jorgepeterbarton]

I'd agree yeh. Planet= round is fine. Often they are called 'terrestrial planets' and sometimes a distinction is made between jupiters/saturns and neptunes/uranii. Maybe other round objects could be taught equally too: 'planetoid moons' 'rogue planets' 'binary planets'=pluto/charon just an appendage. You could literally order by size, and find Pluto is somewhere in there at #17.

[@lucofparis4819]

Also, this main comment's definition would classify some of the binary, trinary, and quaternary stars as planets, which is a big no no. It also gets messier when we tackle on brown dwarfs, which kinda get the same treatment as dwarf planets / planetoids.

[@altrag]

@@lucofparis4819 I think its implicit that "not star" is part of the definition, since stars have their own much stronger definition -- ie: they're massive enough to have ignited fusion in their core. I agree that brown dwarfs are still a tricky one though.

[@jiminverness]

@@altrag What is the IAU's current definition for a star?

[@stereotyp9991]

Hi great guys of PBS Space Time! I'd love to see some cutting edge material covered on your channel: - Loop quantum gravity - Quantised inertia

[@davidhand9721]

I second this. We got one on loop quantum gravity, so I'd add the measurement problem. No more of the unscientific speculation that seems to have taken over.

[@MajorQuux]

The astro folks are about a century behind the math folks: no taxonomy can be both complete and consistent. Bertrand Russell most famously published this in 1901 with Russell’s Paradox, in response to Gottlob Frege, along with Georg Cantor’s set theory. But the idea was known to people like Ernst Zermelo and others in 1899. If there’s one alien planetary engineer (surprisingly named Matt) who terraforms every planet if (and only if) other inhabitants don’t terraform it themselves, then who terraforms Matt’s planet? The final nail in this coffin was in 1930 when Kurt Gödel proved that Russell’s efforts to just build a better set theory were futile. Apparently the IAU didn’t get the memo.

[@AhsimNreiziev]

+[Joel Holveck] If Matt is the sole inhabitant of his planet, then there are no other inhabitants, and thus Matt terraforms his own planet. Elementary modular logic. If Matt's planet was terraformed by means other than people (likely if Matt is not the only inhabitant of his planet), then there is no terraforming for Matt to do on his own planet. If neither of these things are true, Matt will terraform his planet unless someone else beats him to the punch. Now, if you had removed the word "other" from "other inhabitants", the problem would be far more fundamental.....

[@abyssoftus]

The only problem I have is with the 3rd requirement. It ties distance from the sun and mass together in that the further away from the Sun the more massive the planet must be in order to have cleared the neighborhood. If an earth-massed body replaced Pluto then neither it nor Neptune would be a planet. Likewise, the proposed "Planet 9" would likely not be a planet either as in the local of the orbits proposed it would need to almost be a brown dwarf to have cleared its neighborhood.

[@uwilly23]

You said "a universe that contains worlds, some that are plants", but according to the IAU, there are exactly 8 planets in the entire universe because a planet must orbit the Sun. This is why I have a problem with the IAUs definition of planet, they should off come up with a term like, "Major Solar Planets" instead and left planet to be more broad.

[@Merennulli]

The IAU definition is explicitly "not applicable outside the solar system" by design. If humans got this upset about a dwarf planet, just imagine how upset the aliens living on similar planets in other solar systems would feel about it. Of course, they pretend their reason is because we don't have enough data to tell if extra-solar objects have cleared their orbit.

[@fuseteam]

wasn't "must orbit a star"?

[@Merennulli]

@@fuseteam Nope, it's "must orbit the Sun".

[@fuseteam]

@@Merennulli welp that's stupid

[@Merennulli]

@@fuseteam Nothing stupid about it. They don't have enough information to meaningfully start deciding how exoplanets should be categorized yet.

[@dead2675]

Imagine being 9 sibling and dad decides you to kick out of house

[@PanagiotisLafkaridis]

11:23 love the, clearly academic, writing, Matt

[@ultraness]

I think there are plenty of issues with Pluto's classification, not all of which are mentioned here. For one, it was only a small percentage of the scientific community that agreed with the name dwarf planet during the IAU ruling, so it's not as if there was a wide scientific consensus at the time. Next, the criteria for a planet were clearly made with the intention of excluding Pluto, specifically, which was mentioned in this video, but the property that excludes Pluto is poorly phrased and not especially scientific; for instance, Neptune (the third largest planet in the solar system) can jokingly be called a dwarf planet since it hasn't cleared Pluto from its orbit. My issue with the need to clear orbital paths is that Pluto's location in the solar system is basically what demotes it, since an object like Pluto would be considered a planet in another star system, if, say, Pluto was much closer to its star and there were no other larger planets nearby; I wouldn't say Pluto is alone in this problem, as Titan, a moon in name, is much more like Earth than Mercury, a planet in name. I can't say I'm fond of the notion that Pluto had to be demoted so that there wouldn't be "too many" planets, an idea that I take offense to. If anything, I'd much rather children (and adults, for that matter) learn more science; imagine if chemists discounted a new element because the periodic table just has too many elements to remember. Also worth mentioning is the real concern that demoting some celestial bodies to "dwarf" status lessens the public interest in these objects, which cuts into the funding that missions to send probes to Pluto and further can receive; I imagine that's the reason why Alan Stern, and other NASA guys who worked on New Horizons, are so adamantly against the re-classification. Lastly, while I can mention my issues with the ruling and the reasons behind the classification, at the end of the day, it should not be forgotten that "dwarf planet" is just a terrible name. If Pluto must be called something else, at least give it a name that sounds cool, since New Horizons proved without a doubt that Pluto is an amazing celestial body.

[@sebastianhansson6919]

Even as a kid I had issues with Pluto as a planet. I just didn't think the orbit fit with how the other planets worked. Orbit angled way outside of the solar plane? Highly elliptical? Sometime going INSIDE Neptune's orbit?? What is up with that?

[@ultraness]

@@sebastianhansson6919 I think it would have made more sense to demote Pluto based on its strange orbit, except with the orbit not being overly elliptical as a criteria for planetary status, the scientists would probably need to promote Ceres, and we can't have that.

[@robinchesterfield42]

Funnily enough, I went and looked back at my favourite old astronomy book I had as a kid (yes, one of my fave books when I was 6/7 was a book about outer space), flipped to the chapter about Pluto, and to my surprise, there it was! Scientists ALREADY debating whether or not Pluto was even a planet! The date this book came out? 1980. (It's called "Our Universe" by National Geographic.) Now, I dunno about having a weird orbit disqualifying you from being a planet. I always thought Pluto's orbit was _interesting_ , being all hugely long and tilty and crossing over with Neptune's sometimes. That's cool! That's cool, because it's weird. But to me a planet is these things: 1. Round 2. Orbits independently around the sun instead of around a larger planet. That's it. "Clearing the neighborhood"? That's so freaking arbitrary! Pluto hadn't physically changed, and we hadn't, say, just found out that hey, it's not really round at all, it's actually a lumpy little comet! when the IAU made its decision. Pluto was still the same size, shape and mass. It didn't stop BEING what it was. They just changed the name! And why? Mainly because they were discovering a bunch of other round objects in the Kuiper Belt and were like "Oh noooo, that's too many to memorise!" I get it, you don't want to make schoolkids memorize ALL the dwarf planets out there, but...well...maybe just the ones we know more about and that have cool names? I miss the days when Eris was briefly talked about as the possible Tenth Planet. Now we're back to looking for Planet 9. (WE _HAVE_ PLANET 9 ALREADY IT'S CALLED PLUTO oh nevermind...)

[@Sunlight91]

I recognise the argument for a different classification of Pluto, but the name dwarf planet is not well chosen. It is very likely that other solar systems have dwarf planets which are bigger than earth or a dwarf planet that is bigger than another planet in the same system.

[@Mankepanke]

Isn't larger bodies almost guaranteed to have cleared their neighborhood?

[@casacara]

“King of the dwarves” is a pretty sick title, imo

[@ciprianbenec4091]

Eloquent, well put in context and fully explained. 🙇

[@ciprianbenec4091]

This should be presented in schools and debates on the subject.

[@MichaelMiller-rg6or]

I think half the reason Pluto's demotion was a hard pill to swallow, at least for kids that grew up in the 90s was because of that Magic School Bus episode.

[@Exception1]

How massive would an astronomical body in the Kuiper belt need to be in order to clear the neighborhood around its orbit and satisfy the other conditions needed to qualify as a planet? Or how massive would an astronomical body at roughly Pluto's location need to be in order to qualify as a planet? What would be an upper/lower bound on the size of such an object? Would clearing the neighborhood around its orbit mean that if such an object existed then the Kuiper belt would be split in two?

[@MATTFIOCCHI]

Exactly! If we do find Planet X, which is supposed to be huge, it'll still be surrounded by clouds of debris in the range of its orbit, so it won't be a planet!

[@alaingoyette3883]

This Channel has got everything right. Impeccable animation matt

[@Lucas-mf1tc]

"Planet" should simply be used to describe wandering stars. If it looks like a star to the unaided eye and it noticably moves, it's a planet.

[@DrWhom]

yeah, but 8-year olds need to build models of the solar system, and this is the compelling reason we need a cutoff

[@manaphy0993]

Kids these days don't understand what it was like being taught there were 9 planets

[@amfvideos6810]

Ask literally anybody who went to primary school before 2006.

[@MrFleem]

I was taught that Pluto is a planet. I was also taught that dinosaurs were almost all slow lumbering things with pea brains and there was just this one kind that was like a chicken.

[@ColeDedhand]

Pluto was here billions of years before us. Will be here billions of years after us. Could what we call it be any more irrelevant?

[@laosracer12]

A planet.

[@RobinDSaunders]

I'm a few months late to the party, but one of my very favourite songs is about exactly this. It's written from the perspective of the moon Charon, which is so large that it doesn't strictly orbit Pluto - instead, the two orbit one another about a common centre of mass lying in the space between them. The chorus goes: "I'm your moon, you're my moon, we go round and round From out here, it's the rest of the world that looks so small Promise me you will always remember who you are" It's by Jonathan Coulton (famous for Portal's "Still Alive") and there's a wonderful fan-made, hand-drawn video for it here: kzbin.info/www/bejne/a5_TmXZohZZ5iNE

[@accordintojordan4250]

Time-Traveler: *See’s science article* Ha! They listed Pluto as a planet. We must’ve gone back a long time Pluto: Say sike right now

[@CharmsDad]

You failed to mention that this definition was by no means universally accepted. It was passed by a relatively small group using a parliamentary stunt, then they used the same stunt to change the IAU rules so that same stunt couldn’t be used again.

[@MATTFIOCCHI]

Huh, didn't know that part. Makes it seem petty, in addition to arbitrary.

[@johnp893]

You are correct. The new definition has no scientific merit as "hasn't cleared its orbit" is completely vague and not something that could meet the rigid standards of what a scientist would call an "observation". This was a political victory for some self-promoting egomaniacs and a defeat for the scientific community.

[@GoldSrc_]

@@johnp893 It's not "vague", it just means that a planet's orbit should not intersect with another planet's orbit, Pluto is sometimes closer to the Sun than Neptune and crosses Neptune's orbit. Every other planet has its orbit cleared from other planets, Pluto doesn't.

[@johnp893]

Gordon Freeman Then neither does Neptune. Earth has over 10,000 co-orbital asteroids, Jupiter has over 100,000. Are they planets?

[@GoldSrc_]

@@johnp893 Nope, none of those bodies orbit in the same plane as other planets. Just look at Pluto's orbit, it's very inclined with respect to the ecliptic plane, which is a very important thing to keep in mind when trying to classify something a a planet. Most planets don't deviate that much from that plane, just like how you can stay on your lane in the highway but you have a small room to move left or right before you are in a different lane, Pluto is like that guy who swings from lane to lane in the highway lol.

[@tungstentaco495]

the "clearing the neighborhood" criteria has a problem I as far I can see. It brings up the idea that in young solar systems, you could have Neptune and Jupiter sized bodies orbiting a star but have not yet cleared their neighborhoods because not enough time has passed for them to do that. So in those situations, they would not be defined as planets? Personally I would change that rule to just a minimum size threshold of 1000 km diameter. In that scenario, it would put the current number of planets at 11. You would have the currently accepted 8 planets plus Pluto, Eris, and Makemake. I could live with that. Could maybe add Charon to that list in a double planet scenario depending on how that definition current works.

[@evgenijdenisov]

Nice question. I think you get a promotion (from a dwarf planet to a planet) when you clean your room up. It's like the exploits of Hercules who wasn't called a Hero until he had proven himself as one.

[@xSandamx]

definetly my problem with it too. defining a celestial body by its surroundings makes no sense.

[@lionel4685]

@@evgenijdenisov nice thought. We should call them Heroe planets, as opposed to Dwarf planets, and add the taxonomy of Apprentice planets for those dwarf planets that are actual candidates for cleaning their room up.

[@evancombs5159]

That isn't the only issue with the definition. Another issue is being in orbit around a star. It is possible for a planet to be ejected from its system and drift aimlessly in space without its mother star. These two points combined really show the shortcoming of the astronomical community in creating an effective taxonomy. Using an arbitrary measurement like 1000km diameter would not be better. The only correct definitions should be based on physics. My proposal would be a planetoid is any object large enough that its gravity collapses it into a mostly spherical shape. A moon is a planetoid that orbits another planetoid. A planet is a planetoid that orbits a star. A star is a planetoid with enough mass to ignite nuclear fusion. A major planet is a planet that has "cleared" its orbit, a minor planet is a planet that has not "cleared" its orbit. So on and so forth. This would be a proper taxonomy.

[@nocare]

Except clearing an orbit takes size into its definition. Specifically an object must have a mass so large it is not comparable to other objects in its orbit. So an system with a Jupiter sized object would have no other Jupiter sized objects in its orbit in a young solar system or it wouldn't have grown to that size yet. More likely to fall in a grey zone are planets that are mercury sized however objects in such a state will eventually fling each-other into diffrent orbits or collide. They would be dwarf planets until that happens and given there small size there is no real problem with this.

[@TheMcKenzieHaus]

This video was emotional for me. Pluto still rocks

[@InTrancedState]

I was hoping for a 10 second video of you saying 'NO'

[@gotbread2]

But is a dwarf planet not a planet in the same sense a red car is a car?

[@robinchesterfield42]

I think a lot of the rancor/sadness comes from the fact that a lot of us grew up with _nine_ planets in the solar system. Then suddenly one was kicked out of the family! Oh, sure, it's still KINDA called a planet. But it's not in the rhymes and schoolchild-learned lists anymore. We learned stuff like My Very Excellent Mother Just Sold Us Nine Pies, and now... It's like, a matter of "Is it in The Group, yes or no?" Used to be yes. Now it's no. And since Pluto was a planet for several decades and _didn't actually change at all before being demoted_ , that means a LOT of people grew up with Pluto as one of the nine, one of the _main_ part of Our Solar System, or knew that later on as an adult. Nowadays we've got teenagers born after the IAU decision, so they won't be bothered by it, but...

[@ondrahruby6325]

"Pluto is a planet" - Jerry Smith

[@IPwn3dJo]

I think I know what the A in NASA means now

[@AyaJuni]

authority argument

[@MrPooPooJohn]

Stay scientific, Jerry.

[@RedLeader327]

And me.

[@vlada]

Wubba lubba dub dub!

[@kinomora-gaming]

Glad to see you guys using the Discord platform :D

[@masterhypnos6783]

Great information in this video, and I like that the guy narrating this sounds like Terence Stamp. Just listening to him, I keep expecting him to shout out, “You will bow down before me! Both you, and then one day your heirs!”

[@InfectedChris]

Yes, it is. It was when I was a kid and will be forever.

[@wmgthilgen]

So you still believe in Santa, Elves, Tooth Fairy's, Jesus, Unicorn's etc etc etc.

[@InfectedChris]

William Guy Thilgen Jr. Nice fallacy.

[@robinchesterfield42]

@@wmgthilgen NICE strawman there! Did you make it yourself? It's almost October, I'd suggest using him as a Halloween decoration outside your house.

[@johnbeamon]

The whole bit around the political appointee over NASA was quietly, succinctly brutal in its elegance. Well done, sir.

[@nicholashylton6857]

Agreed. I noticed that too.

[@kingpin6989]

Except that he's right. Pluto IS and will ALWAYS be a planet.

[@lordgarion514]

@@kingpin6989 Pluto isn't even grown up enough to clean up its room. Leaving shit just floating all around the sun like it's better than the others.

[@VernAfterReading]

Also, a total straw man. A lot easier than taking on the planetary scientists who think the IAU definition is total garbage for how utterly unworkable it is if you going to study, you know, actual planets.

[@TheoEvian]

@@VernAfterReading So, what definition do you propose?

[@SmogandBlack]

My favorite PBS video ever. I'm curious (and I'll be indebted to anyone that will be able to enlighten me): does Matt write his own texts all by himself? Let me be clear: it wouldn't make any difference... as said, I'm just curious. Hi to everybody out there, sharing this Spacetime...

[@jennyreid722]

In the description it says he does with another writer called Drew

[@SmogandBlack]

@@jennyreid722 Thank you very much 😊: Drew Rosen, that's right (this question was me 3 years ago... eventually I found out...). Sincere thanks anyway, Jen 😊.

[@Anthony-jd3tm]

This actually convinced me.... Well done.

[@Jaizensama]

So can Jupiter be a failed brown dwarf?

[@kvlt1349]

You'd need to smash another dozen Jupiters into Jupiter to get to the minimum size to be a brown dwarf. I vote no.

[@ThePiotrekpecet]

Every planet technically is

[@guytech7310]

No, but Jupiter is not a planet either, its a gas giant /sarc

[@delwoodbarker]

If Pluto is not a planet, then Europe is not a continent.

[@evgenijdenisov]

Yes, they are not.

[@totalermist]

How even? Both concepts are orthogonal. Your statement is devoid of any logic. Both continent and planet are terms arbitrarily defined by a group of professionals (geographers/geologists and astronomers). It shouldn't matter to laypeople what terms scientists use to classify things.

[@LNRMusicCuration]

Love to see some pluto content. Makes for a lovely profile picture!

[@JasonKCarter]

I’m just teaching my kids about all the worlds. They are all fascinating in their own ways.

[@simianbarcode3011]

Pluto is a planet IN OUR HEARTS! that's all that matters...

[@gklnth187]

No.. Only Uranus can fit inside heart..

[@davidburnham4404]

Pluto is a Planet despite what some say.

[@carto4028]

Listen guys......can we at least give it a participation award. Like every other dwarf planet the exact same size as Pluto would be considered a dwarf planet but Pluto itself gets the participation planet status.

[@supersasquatch]

"The planets.. what a concept" - Doctor Jimes Tooper

[@Robyrob7771]

No mention of Cheron. Is it still a moon? Or is this a binary dwarf planet system?

[@danfr]

It’s still a moon, but I would love to see binary pairs properly recognized. That said I can’t come up with a good definition that doesn’t come with caveats, given that Jupiter is so massive and far away that the Sun-Jupiter barycenter lies outside of the sun.

[@anarchyantz1564]

Apparently its a binary dwarf system as they both rotate around one another. It may change depending on what Neil DeGrasse Tyson thinks, as he was the most vocal to de planet Pluto.

[@radicalxedward8047]

4th rule for being classified a planet: “If the planet has a giant heart on it, it’s a planet. This rule supersedes the previous 3.”

[@radicaledwards3449]

I think I know but I don't think I think

[@slybunda]

a simple yes or no answer would have had the video over in 3 seconds.

[@User-inthemorning]

“There is goes again, just shrank a little”

[@Digikidthevoiceofreason]

LOL!!! R&M reference.

[@User-inthemorning]

DigikidForever you got it 😁

[@chrissr318]

Mercury didnt clear its "neighborhood" that was the sun

[@trevorwilson6683]

Dieter Gaudlitz it pulls everything smaller right in though, doesn’t it...

[@bragod]

Now just came to my mind: If a planet is has its orbit changed, say due to a close encounter with a massive objetc, to the Kuiper belt of its own system, It can suddenly be reclassified as a Dwarf planet, even if its 10 times more massiva than all the belt combined! They should had added a mass requirement (being more massive than all other objects on your orbital neighborhood combined).

[@TheSmileMile]

My problem was more "What do you mean by 'cleared it's orbit?'" There are Asteroids that pass through Earth's orbit, or orbit in resonance with the Earth, and if the Earth isn't a planet, what is? It seems like the new definition was not just conceived to push Pluto out, but ILLconceved to push Pluto out.

[@RandomAcronyms]

You can't "pass thought" an orbit and also be on the same orbit. Pluto has many other asteroids that are on the same orbit as it every single day of the year, not just a random rock passing by like Earth. If Pluto where more massive, the smaller objects in the same orbit would have been thrown off the orbit by Pluto, making it a Planet.

[@cauldronofstardust4113]

You do realize that Jupiter has more junk in its orbiting in its orbit than anything else in our solar system, right. So, the orbit definition isn’t that adequate either to demote Pluto. Unless you want to demote Jupiter as well, in which case my avatar would like a word with you behind the woodshed.

[@davidkieltyka9]

I think we could preserve the special status of the Great Eight (or whatever we may decide to call Mercury-Neptune) while still using the term *planet* for larger KBOs too. Regardless, IMO much of the rancor over this issue traces back to the way the IAU demoted Pluto. It was a bodge job, to put it politely. The declaration that a planet must “clear its orbit” was inserted specifically to exclude Pluto. IOW, the result was gamed. The IAU should reopen the matter and go through the decision process more deliberately, allowing for greater and more thorough participation. This would give their decision, whatever it is, more legitimacy.

[@EvenTheDogAgrees]

On the other hand, that "must've cleared it's orbital path" clause does make sense. It's how most of us think of planets in the first place: something that orbits a star, is more or less round, kinda big, and travels either alone or accompanied by smaller objects that orbit it, rather than the central star.

[@kevincrosby3953]

Yes you hit the nail on the head. "Science" is highly political.