Daniel and Jorge Explain the UniverseCentaurs are real, but not on Earth. Daniel and Jorge talk about the weird objects astronomers call a "space centaur"
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Hey Daniel, do you think the universe is still capable of surprising us?
What do you mean? It's blowing my mind all the time.
That is what I mean. You're always saying that we could discover anything out there.
I do say that, like you know, there might be huge purple dragons out there past the edge of the observable universe.
Okay, yeah, but then what if we actually discover huge purple dragons. Would you be like, eh, I saw that coming.
No, I would think like, wow, so cool. I wonder how we could talk to dragons about physics.
But you don't think there are actually dragons in space? Do you?
Probably not? But hey, some future astronomer listening today will discover a new kind of fiery star out there and call it a space dragon.
I guess you could say it be in the night sky, you know, night with a K.
Sir Jorge, that is a terrible joke.
I am Orge, I'm a cartoonist and the creator of PhD comics.
Hi. I'm Daniel. I'm a particle physicist, and I really do want to meet a space dragon.
Welcome to our podcast, Daniel and Orge Explain the Universe, a production of iHeartRadio.
In which we talk about all the things that are out there in the universe, the things that amaze us, the things that blow our minds, the things that make us curious, and also the things that we wonder if they are out there, the crazy hypotheticals, the possible, the things that will blow the minds of future generations and explain all of them to you.
Is this Daniel where science fiction meets fantasy.
Is who has been a tight connection between science and science fiction, and that connection is the fantasy of science fiction authors thinking of crazy stuff we might see one day.
You mean, like dungeons and space dragons.
Yeah, exactly. And I think that there's a lot of folks out there who are scientists or read science fiction who also appreciate fantasy and crazy dragons and magic and wizards and all that stuff.
Do you think there's some science spaces for any of that.
No, I think it's all based in mythology, but it's all creative and I like reading it. So we usually talk about science fiction on this program, but I'm also a big reader of fantasy novels.
But yeah, we talk about all the amazing things out there in the universe, all of the weird and unexplained objects, And there's a lot of stuff out there in the universe and in space, floating out there. Who knows what's out there?
Yes, And the more we look out there in space, the more we discover that there are lots of different kinds of things. We never even imagined, and also that the distinctions between the categories we thought were crisp and clear are a little fuzzier than we understood.
Yeah, there's a pretty big diversity out there, because it's not just suns and planets out in space floating out there and the darkness of the cosmos. But there's other kinds of objects, and sometimes they're kind of hard to categorize.
That's right. The Solar System is more than just a Sun and a few planets and a couple of moons. There's a huge spectrum of stuff all the way down from space dust up to the Sun itself and basically everything in between. And where we draw the lines. What we call a planet, what we call a brown dwarf, what we call a star, what we call an asteroid, sometimes just has like a historical basis more than a scientific one.
So if there are dwarf planets, Daniel, are there also elf planets?
Those have been taken over by the dwarfs. That's all that's left.
The dwarfs won that war, they leave for the West already.
That's right. There's a whole other set of Solar systems, deep deep in the galaxy, where the elves have retreated to.
But I mean this is sort of a continuing conversation I feel with astronomers, like what counts as a planet, as an asteroid, as a space rock, or even it's a sun. It's hard to tell the difference between a sun and a planet.
Yeah, exactly, if Jupiter was bigger, it would be right on that threshold. Might argue like, it's a really big planet. No, it's a failed star. No it's a brown dwarf. And this isn't just like astronomers being picky or astronomers coming up with silly names for things. This just reflects how we look out at the sky and see different kind of things and try to make sense of them. You can't just say, hey, there's lots of stuff out there, we can't categorize it at all. You have to try to say, we're talking about these kinds of stuff and that kind of stuff, And when you face a bunch of messy observations, you have to try to find categories and patterns.
Yeah. So today we'll be talking about one such object in the Solar System, one that has a pretty mythic name to the On the program, we'll be talking about what is a space centaur.
And what happens when they do battle with space dragons.
Or space unicorns. That's the one I want to right around in.
Well, that is an ancient rivalry unicorns versus centaurs. They do not get along really.
Oh man, can you have us centaur with a horn?
Where would the horn go? Exactly? Space un centaur would go on the forehead of the guy or the woman.
Where else would it go?
I don't know.
I mean, I guess it could come out of their chest?
Yeah, exactly. Like I have all lots of basic questions about centaurs, like where is their belly button? You know, is it sort of on the person part or all the way down or like, you know, anyway, there's a lot of interesting questions you can talk about when it comes to centaurs.
Well, but that's a different podcast. That would be the Dungeons and Space Dragons podcast.
Daniel and Jorge explain the universe of fantasy creatures.
But yeah, there is such a thing as a space center. Like this is actually something that physicists talk about in conferences and in papers.
That's right. Yeah, It's something pretty awesome and it came up on the podcast a few weeks ago. Just sort of obliquely when we were talking about other things in the Solar System, and we got a bunch of listeners right in saying, what is that real? Are there actually space centaurs? And so we thought we we dive into it into a whole episode.
Hmmm, they thought you were kidding or so they're calling us out.
They are calling us out, and we are stepping up and explaining exactly what a space centaur actually is.
You didn't just make all this stuff up twenty minutes before we started.
No, No, this is not a fiction podcast. This is real. But you know, sometimes in science we borrow words from other fields, We borrow them from art or from philosophy to try to describe some relationship we see, to try to capture something about this new kind of object that we can't describe in any other way. And sometimes that seems creative and clever, and sometimes it seems awkward and clunky.
To what percentage, Daniel, what percentage of physics names you think are awkward versus right on?
Well, I would estimate that you would place at about ninety five percent clunky. But I think there's some art to them, you know, I think sometimes I see where they're going, even if they didn't necessarily really hit the target.
All right, Well, as usual, we were wondering how many people out there had heard of a space centaur or even knew what it could possibly be. So Daniel went out there into the wilds of the internet to ask people what is a space centaur?
And thank you to everybody who volunteered to answer this particularly strange question. If you are willing to put your baseless, unresearched answers to difficult physics questions on the podcast, please write to me at questions at Daniel and Jorge dot com.
So think about it for a second. If someone approached you and asked you what a space centaur is, what would you say. Here's what listeners had to say.
I do not know what a space centaur is, but I know what a centaur is, so I'm guessing it's an astrological phenomena that feels like magic, but it's actually science.
I have no idea what that is, but it sounds like a new kind of tesla or maybe a rocket of some kind. The Space Center is a NASA operate to a museum where villagers can engage you with space science.
If it isn't a mythical beast that flies through the cosmos, then I imagine it's a classification of some kind. I have a memory of it being something to do with maybe an unstable orbit or some kind of like collision course in the future.
I think I heard about these things a few weeks ago on Discovery, So I see or rocky objects between.
Jupiter and neptuned.
A space centaur sounds like a constellation, maybe in your Alpha Centauri.
If not that, then some kind of a nebula.
Maybe A space center is a child of a human from Earth and a human born in another planet sey Mars, for example.
So I don't know about you, but I feel like we got exceptionally creative answers this week.
Mm a tesla h.
I think my favorite is the child of a human from Earth and a human born on another planet. What a great idea to call that a space centaur.
That is pretty good. It's like the right now science fiction and fantasy right now exactly.
I hope that sparked somebody to write their whole novel.
Nobody thought it was an actual centaur. Everyone sort of assumed it's some kind of object in space.
Yeah, but it's such a weird thing that nobody heard of that the guesses were pretty wide. I mean, one person was guessing that it was a space center because I think the idea of a centaur was so strange they must have thought I made a typo in the question, Mmmm, a space center does make more sense than a space centaur.
All right, well, let's jump into it, Daniel. I assume the answer is going to be very magical and legendary, but step us through it. What is a space centaur?
So to understand what a centaur is, you first have to understand two other things, and that's asteroids and comets, because that's what you were saying before. You know, you look out into space and you see lots of really weird stuff out there, and the deeper you look, the more weird stuff you see, and the more we learn that there's a lot of objects out there in space. It's not just planets and the Sun. And if you uns, there are zillions of asteroids, and there's lots of comets, and then out there beyond Pluto, there's an enormous number of frozen rocks. So astronomers are trying to come to grift with this incredible number and variety of stuff by giving them all names that describe roughly what they do. Some of these names are like anchored in history because they come from very early observations. Right, Astronomy is a field that's hundreds or thousands of years old. So to understand what a centaur is, you really need to understand first what an asteroid is and what a comet is. According to what modern astronomers say, is.
That another mythical rivalry like unicornss a centaurs asteroids versus comets.
No asteroids and comets get along. In fact, sometimes they mix and form space centaurs or.
A space mermaids. Oh my goodness, that's the next level pace mermaids.
Yeah, exactly. That would have been even a better name, because it makes sense for things to swim through space rather than gallop through space.
There with an unknown belly button location.
Yeah, that's right. Maybe they can swim through the sea of dark matter that's out there using their dark matter tails.
M and lure astronauts to their doom. All right, So it sounds like we need to understand what asteroids and comets are, and I'm guessing maybe centaurs. It's like a mix of the two or somewhere in between.
Yeah, exactly. So an asteroid is a really cool object. It's basically just a big rock floating out in space that didn't get gathered together into a moon or a planet. But it has a really interesting history. The word asteroid basically means not a star because it's something that early astronomers saw out there in space. But it was too small to look like a planet.
Right.
You couldn't like see a disk, but it moved the way a planet did. It wasn't so far away, it didn't move like a star. So it's this weird object that was discovered when they say, well, it must be nearby because it moves like a planet, but it's really really small and it looks like a star. So they gave you this new name.
Oh interesting. I guess I hadn't thought about it that we would have discovered asteroids before we had powerful telescopes, right, I guess at the beginning, it was just like a strangely moving pinpoint of light in the night's cut exactly.
An Asteroids, like planets, don't shine light, right, They're just big dark rocks, but they can reflect light, and so if light goes from the Sun and bounces off it and comes to Earth. Then we can see them, and that's good because we'd like to know where the asteroids are so that we know they're not going to smash into the Earth. And we identified a few of them very very early on. It was like in the eighteen hundreds we had already seen ten of them. These are the bigger ones, the shinier ones, and so we could see that they were out there and they were floating around the Solar System. And for a long time, people like didn't even distinguish between a planet and an asteroid, and science papers from like the eighteen hundreds, those two words are used interchangeably.
It just means like a floating object in space that reflects light.
Yeah, it's not a star. It's closer by, it's like orbiting our Sun and it's reflecting light. And from that point of view, what's the difference between Mars and a really big asteroid. They're both just big rocks in space, right. But then as you learn about these objects you start to distinguish them. It's like, well, planets move in their own orbit and basically have cleared a path, whereas most asteroids are in a big belt and so you come up with these ways of talking about things because they're related, But they are also important differences between planets and asteroids.
It's not just a difference of size like I would think it'd be like a size threshold that you have to meet to be a planet. Isn't that what happened to Pluto, Like it wasn't big enough, so it got downgraded.
Yeah, that is sort of what happened to Pluto. But it's also context. Like, Pluto we found and it's out there and it's moving sort of like a planet, But then we found that Pluto is actually just one example of a lot of different objects that are deep out there in the Solar System, and it's not even necessarily the biggest, and so calling it a planet would mean you have to call all those other ones a planet also. So then yeah, they made an arbitrary distinction. They're like, sorry, we're going to define a planet to be just bigger than Pluto to sort of get Pluto out the door.
Is that why? Because they didn't want to admit there were a lot of planets in the Solar System.
Yeah, well, they didn't feel comfortable with the idea of having lots and lots of planets and an unknown number of planets, because out there past Pluto there is an enormous number of these things. These things are called trans Neptunian objects, and some of them are called plutoids or plutinos. But there's a huge number of these things out there. And if you said Pluto is a planet, then you'd have to call them all planets. And you know, planets have a historically important name, you know, like we'd like to think it's a special class of objects in the Solar System that we call planets because we live on one. So yeah, we could have gone with like there are many many planets, but they wanted to make it special.
They wanted to reserve the name for special occasions. Yeah, that was kind of snobby.
I guess it was like, you know, you have friends, and you have best friends, and you could say, well, all my friends are my best friends, or you could acknowledge that some of your friends are actually closer than other friends.
Right, I do have a friend who calls all of our friends best friends. It's so confusing something there you go exactly, So then what was the rationale or what was the official excuse that they go by size.
The long saga of the definition Pluto I think deserves its own episode. We can go through the details of that. But we were saying that asteroids were discovered, you know, in the eighteen hundreds, we have about ten of them, and then it rapidly cranked up. We had like discovered a thousand asteroids by the early nineteen hundreds, and by now we know that there are many, many of these things. They are like probably more than a million asteroids, and a lot of them are floating in this asteroid belt, which is this big chunk of space between Mars and Jupiter, and some of them are actually co orbiting with Jupiter. Like Jupiter has its orbit right, it's this big circle, and in other places in that same orbit where Jupiter isn't there are big blobs of asteroids, big clumps of asteroids floating in the same path.
They can share the same orbit. Wouldn't they have a different speed or something.
They can share the same orbit, and they have a cool name. They're called Jupiter trojans. No, they really are called Jupiter trojans. And they get into these weird gravitational resonances with Jupiter because Jupiter is having a big influence on all the stuff that's going on in the Solar System out there, So you can't just ignore Jupiter. Jupiter is a huge gravitational attraction. Remember that ninety nine percent of the stuff in the Solar System is the Sun, and of that remaining one percent, Jupiter is most of it. Jupiter's like ninety nine percent of that one percent. So to first approximation, the Solar System is just the Sun and Jupiter. So if you're out there near Jupiter, it has a huge influence on what's happening gravitationally. And some of these rocks get tossed down into the inner Solar System by Jupiter, they get disturbed, and some of them found these resonances where they can stay happily in Jupiter's orbit.
All right, Well, that's an asteroid, and so that's one half of the space centaur puzzle. The other have our comets, which we'll get into in a short bit. But first let's take a quick break.
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All right, Dany, we're talking about space.
Mermaids, unicorns, man unicorns.
Space unicorns I guess maybe more like space vegases too. That could be pretty cool that they're like half birds have horses.
Right, Yeah? Or what about griffins. Are those like half birds half lions, right? Those would be cool space griffins.
Space hippogriffs. That's the nice level.
Most of these things we just made up. But some of these things are real and are out there in space. But they're also just sort of funny names that astronomers give to things to try to show us the relationships between what they've discovered.
All right, So an asteroid is a space rock. That's sort of the definition Somewhere between like a baseball and what like the size of the Moon is what would be considered an asteroid.
Yeah, they're like between a meter and up to like five hundred kilometers. The biggest one called Vesta, is like five hundred kilometers wide. And they're mostly rocks, and they're mostly in the Inner Solar System, so they don't have a lot of ice. So they can be pretty big and they're mostly rock and they are in the Inner Solar System. Those are the key points to be an asteroid.
Really, what if you're a big rock but you're outside of the Inner Solar System.
But bomb you might be a centaur.
Oh I see, it's like a location. It's like a discriminating by where you're from, all right, So that's one half of the puzzle. The other half are comets. Now, comets are different than asteroids.
Are different from asteroids. They come from a different place in the Solar System. They come from out beyond Neptune, the Kuiper Belt. This is huge collection of rocky and icy objects. So that's the second key. Comets come from deeper out either the Kuiper Belt or the Oort Cloud, and they are made of different stuff. They tend to have a lot more ice in them. They're these big, dirty snowballs of ice and dust. And there's a reason for that. There's more ice out in the far edges of the Solar System because it was colder out there. Now, water in the inner Solar System got sort of blown out by the pressure from the Sun out to the outer Solar System. So rocks that coalesce out there deeper in space tend to have more ice in them. So comets come from the Kuiper Belt or the Ort cloud, which is this hypothetical collection of trillions of icy objects deep out there, and they tend to be made more of ice.
Like water ice or like methane ice, both kinds of ice or other kinds of liquids, all kinds of ice.
And don't get me started on how planetary geologist talk about ice like they talk about the ice giants of Neptune and they say these things are filled with water ice, but they don't actually mean these things are frozen water to them, like a water ice. It's a whole category of states of water that could be solid but could also be technically a liquid, but are not actually frozen water. So the whole idea of an ice is a very sort of confusing and general topic which is badly named. But in general, there is a lot of frozen water and a lot of various organic ices out there in the deep Solar system.
All right, we won't get you started. I'm not Daniel. Although ice giants also sounds like a mythological creature.
Well, Neptune is real and it's out there, and it's called an ice giant, even if it has a lot of water and no ice. But these comets, they also tend to be smaller, like, you know, they're not up to five hundred kilometers wide. They're like five to twenty five miles wide. And you can tell that they're made of different stuff because when they plummet to the inner Solar system, they get a coma and they get a tail, like their edges tend to be burned off by the sun the solar pressure, it's frying the outside, and you get this long tail of material that's basically coming off of the comet. So they're not like as densely packed that they tend to be more susceptible to the Sun.
I guess further out there, away from the Sun, it's more likely for molecules to form into solids because it's colder, and so there's just more things you can make rocks out of, whereas maybe closer to the Sun, you know, there are certain things like water or methane that evaporate.
Yeah, that's right. Your distance to the Sun definitely changes the composition of materials in the solar system, which are the basic building blocks of everything we're talking about. And it's really fascinating. And you know, we've only until recently seen one example of a solar system, ours, and now we're starting to see other solar systems and we're looking at those and we're saying, hey, are the patterns that are in our solar system also present in those? And we're finding really surprising things, like we're finding huge planets like the size of Jupiter really really close to the Sun, not just in the outer Solar system. These are called hot Jupiters. We actually did a whole fun podcast episode about this is our Solar system weird and all the things we're learning about our solar system by looking at others. But in general, what you say is corrected. That tend to be different kinds of things deeper in the Solar system than closer in, and this affects how these objects come together. And it's one reason why comets are different from asteroids because they're made of different stuff, because they come from further app interesting.
Can we see asteroids and comets and other solar systems yet? And B wouldn't it be cool to have a novel about big space war between our centaurs and there are unicorns and another solar systems mermaids. That would be epic.
I want to read a book called exo Mermaids.
That would be pretty cool. Mermaids.
No, we think we have seen a comet from another solar system, but we can't see them in their solar system. We think that Omuamua, that weird cigar shaped object that came through our solar system.
A couple of years ago, was an exomrmaid that.
Was probably a lost comet from another solar system, but we don't know. It came through really fast, and we only spotted it when it was halfway through the solar system, so we only got good pictures as it was on its way out. So there's still a lot of questions about what exactly O Mua Mua was, But most likely it was something from another solar system's equivalent of the Ort cloud that got lost and ejected into space and drifted over here. But we can't see these things from other solar systems because they're so small, Like if you wanted to point your telescope at another star, we could just barely detect the planets which are these huge masses. So we're very far from being able to see exo asteroids or exocomets or exo mermaids.
All right, So those are comets. And now do comets have sized restrictions too? Or do they also range from like small to gigantic.
They tend to be smaller than asteroids, and that's because they formed deeper out and they just haven't gathered together into larger objects, and Neptune tends to keep these things small. Neptune is also a really big planet, and so its gravity tends to break stuff up because of tidal forces, and so anything in the Kuiper Belt that would gather together into a larger object generally gets torn apart by Neptune. It's like the big bully on the playground out there and doesn't want anything to challenge its supremacy. So they tend to be up to about like twenty five miles wide.
We think, wow, so there's an active effort not to have more planets.
That's right. It's a good old boys club you know, and it's only worth something if it's exclusive. You can keep people out.
Neptune's the bouncer, it's the enforcer exactly, all right. So that those are asteroids and commets, And now I'm guessing that a space centaur is like a mix of the two. Is it like half asteroid half comet, Like the top half is one, the bottom half is another.
Where do you put the horn on the space centaur exactly?
Or the belly button right and the asteroids half belly buttons.
Daniel depends on how they are born a deep mystery of science.
Or do they have multiple belly button.
Well, you're sort of right. A space centaur is half asteroids half comet, but not in the sense that a centaur is. It's not like you take an asteroid, cut it in half and slap it onto the half of a comet and this weird hybrid object you would call a centaur. That would be pretty cool.
But like the tail trailing, that would be like a pretty killer comet. There.
Yeah, it's sort of like punk, you know, like shave half your head and have the other half long or something, or maybe it's like a mullet.
This is in the front rocking the front party in the back.
Anyway, a centaur is not an actual mix of an asteroid and a comet. It's an object which has some of the characteristics of both, so it doesn't fall neatly into either category. And this is what I was saying earlier, is that as we look deeper into the Solar System and catalog more and more stuff, we find that the transitions between our categories are kind of fluid and fuzzy and in the end kind of arbitrary. You know, we have to make categorizations so we can talk about stuff. You know, when you go to a meeting of astronom and you say, I'm studying the planets, you don't want to every time have to define what you mean by a Planet's that you got to have words we can all agree on, even if they are arbitrary. So what we've discovered is that there is a population of rocks out there which don't fall nicely into either the category of asteroid or of comet.
So the solution was give it a cool name, and now everyone's happy.
And now everyone's happy.
But now everyone said arguing about whether or not accounts as a space center or not.
Yeah, exactly. And so these things are fun because they're sort of like comets because we think they come from deeper in the Solar System than asteroids. They're on these sort of longer elliptical orbits. Their orbits go out to like between Jupiter and Neptune. All the asteroids are in the inner Solar System, but these space centaurs they go out all the way to Neptune sometimes. So they're sort of like comets because they also they have some of these comas, like you can see these sort of fuzz around them that's getting blown off by the Sun. So they seem sort of like comets because they come from deeper in the Solar System and they have this fuzz. But they're also like asteroids because they're really really big. Some of them are way too big to be considered comets. And they also they cross the paths of these giant planets like comets and unlike asteroids. So there really are sort of a mix of the characteristics of the two different things.
So these are objects that they have like a tail like comets, like they have you know, like a trail of stuff facing away from the Sun of like melted water or liquid.
They don't have a tail to have a coma.
What's the difference.
So a tail usually comes if you have like stuff that can be vaporized, like water or other things which can be vaporized, and a dusk coma is more like, you know, the little bits of stuff on it are sort of floating around it. These things are big enough that they can have their own gravity, so they can sort of hold onto these things. In fact, one of them is so big it has its own rings system, like you know Saturn has rings.
Who.
Yeah, there's this one centaur. It's called Chariklo and it's three hundred kilometers wide. It's the biggest known centaur and it orbits between Saturn and Urinus and it has rings around it. That's how big it is. It's has its own gravity.
Wow, what do you call the moon of a centaur?
Daniel, I'm gonna asked to defer to the official astronomy naming department.
Like a space ferry, I think so, yes, a nymph maybe a space nymph ego? All right, So it's like it has an entourage. It's not just the rock. It's like a rock with some fuzz.
Yeah, And that tells you a little bit about what it's made out of that. There's a big component of sort of space dust in there, not just like big deposits of metal and rock like an asteroid, more like space dust like a comet. And so that makes it more like a comet and less like an asteroid.
It doesn't have ice, or does it.
Some of them may be icy. These things are much more rare than the other ones, and so they're not as well. There's only like two hundred and fifty of them that have actually been identified, but you know, we can only really see the bigger ones. So the estimates range from like forty thousand of these things too. There might be ten million of these things out there in the Solar System.
Okay, so then it's like an asteroid, you said, because of its size, but also its orbit.
Yeah, it's it's like an asteroid because it's really really big, and it's sort of unlike an asteroid because of its orbit. Like asteroids tend to stay either in the asteroid belt or in Jupiter's orbit. These Jupiter trojans that we talked about before, these guys tend to be more stable than a comet, right, but they have these orbits that are really long and elliptical, and they pass the giant planets that cross over the orbits of the giant planets. Sometimes they're further out than Jubiter, sometimes they're closer in than Jupiter, so that sort of makes them more like a comet. But then again there's sort of big, like an asteroid.
Interesting. I don't know, I'm not getting a big comet vibe from these, you know what I mean, Like it feels like maybe just like a rogue asteroid or something.
All right, Well, you know, on the comet side of it, they have these big elliptical orbits, and we think that maybe they came from the Kuiper Belt. Like, these things don't look like the same kind of material that makes up asteroids. They're made of more of the same stuff that comets are made out of.
So I guess this is the kind of argument that astronomers would have a conferences. They're like, oh, but it's big, so it must be an asteroid. No, it has this weird orbit, so it must be a comment. So that's why they came up with the new name.
Yeah, yeah, exactly. And of course nobody even agrees on what the definition of a space centaur is. There's like seven different definitions of a space center.
Different definitions for real, Yeah.
For real, Like JPL has one, the Jet Propulsion Lab in Pasadena down here in southern California. They define a space centaur in one way. And then there's another group called the Minor Planet Center, which is an important institution in astronomy, and they have a different definition for what a space centaur is. And the difference is in like how you measure the orbit details doesn't matter if you cross Neptune or if you cross Jupiter. And these are just like totally arbitrary but conflicting definitions of what a space centauri is.
So I guess there's such a weird variety of stuff out there that you know, you kind of need more names to be able to talk about all these things. And it gets tricky when you try to put things into bins.
Or you could just be inclusive and say, hey, there's just sort of stuff out there and they're all my best friends, and they're all a little bit different, and you can categorize them by you know, their orbit and their composition and not get so hung up on names.
I guess space stuff, planet stars, everything in between is just space stuff.
It's all just particles to me, right, this is a big collection of particles, a little collection of particles. What's the difference?
I see too, particle physicist, I guess all five percent of the universe looks like a particle. All right, let's get into where they actually come from and if we have actually seen some with our very own eyes. But first, let's take another quick break.
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All right, Daniel, We're talking about space centaurs, which are a mix of asteroids and comets that are like, you know, space giant space rocks that are kind of in between. They're big and rocky, but they also have these weird orbits that make them sort of like comets.
Yeah, and so they're sort of a mix between the two different things. And some things are called comets, some things are called asteroids, some things are called centaurs. And then you got these weird objects that nobody agrees about because they fall sort of like in between the definitions from different organizations. So there's an object, for example, called Chiron, which some folks classify as a comet, some folks classify as an asteroid, and some folks classify as a space centaur. So it's a little bit of everything.
Wow.
Yeah, I guess there's no agreed upon a set of definitions, Like there's no International Space Stuff Naming Committee.
No.
I think the problem is there are too many of those committees and they don't agree with each other. And so I think this controversy about Pluto and is it a planet or is it a dwarf planet or whatever, it's just the tip of the iceberg. It's just a tip of the frozen comet. When it comes to like the naming controversies we're going to be facing in the future as we discover more and more stuff out there in the Solar System, and people are going to be arguing like should you name stuff based on where it is now or where you think it was formed, or what it's made out of, or it's possible history or its gravitational role in the Solar System. And there's lots of philosophical differences about how you categorize this stuff that going to be hearing more and more about in the future.
I guess maybe some naming groups are like you know, committees, some of them are groups, some of them are centers. So they're sort of a naming war for those two.
Yeah, exactly, the naming centaur wars.
All right, well, step us through, or where can we see one and what do they look like?
So we've never actually photographed one up close, like we've identified them in telescopes. We see these things, we can tell that they're there. They reflect light, but we've never like passed a space probe by one to get a close up picture the way we have of asteroids and of comets, and of course of planets and dwarf planets and all those other kinds of things. So space centaurs are one of those last things that are really unexplored in our solar system, and there's some really fascinating questions about what they are and where they come from. Like question number one is why do they have their weird colors?
They have colors. There's different colored space centaurs.
Yeah, there are two different kinds of space centaurs at least, and they range from very very red sort of like the surface of Mars, to much more blue, sort of like Uranus. And so that's fascinating that there's these two camps. There's like two kinds of centaurs. I don't know which ones are the good ones and which ones are the evil ones, or if it's much more nuanced than that, but there are red and there are blue centaur.
Interesting. Wait, so we don't have a photograph of them, but we can tell from the light that they reflect what color they are, like they look like pinpoints, but like a red pinpoint and a blue pinpoint sometimes hmm.
Yeah, just like when you look at the night sky, you can tell which planet is Mars because it actually looks red to the naked eye. Even though your naked eye can't really like see the size of Mars, you can still measure the light that comes from a pin prick. And that's the limitation of our knowledge about space centaurs.
So far.
We basically just see them as pin pricks in telescopes because we've never done a close up flyby.
And now there's also a little bit of controversy about these objects.
Yeah, because the color is an important clue. Like, one question we'd like to ask is where did these things come from? Where were they made? Because remember, we're interested in studying the Solar System not just because stuff out there in space is cool it is, but because we think it tells us a story about how the Solar System was formed and what happened and where everything came from and whether it was unusual. And we think that a lot of these objects can tell us about that story based on where they are now. And the way we do that is we build a complete model of how the Solar System was formed, and we try to compare what that predicts to what we actually see out there in space and where there's something we don't understand that tells us as something in our model is wrong. And so we're interested in, like where did these space centaurs form. Did they form with the asteroids and then get sort of knocked out into weirder, longer orbits, or did they form with the comets and somehow get preferentially selected and pulled into the inner Solar system somehow? And so one great way to do that is to look at their composition, and we can't really do that without sampling them, but we can get a clue by looking at their light, so looking at whether they reflect red or blue light and comparing that to what we see from other parts of the Solar system. Like you might think, well, if these things are red and blue, what else out there is red and blue? And if you look at the Kuiper Belt, where we think that these things might come from, we find that those objects are not actually by colored. There aren't red and blue objects out there in the Kuiper belts.
Wait, if something's red and blue, would it be purple? Can there be purple centaurs? If not purple dragons?
Purple dragons? No, we mean that the Kuiper Belt doesn't necessarily have a distribution of colors the way we see in centaurs. Like centaurs tend to be red or blue. You don't have an individual centaur that's red and blue. You have red centaurs and blue centaurs. But if you look out in the Kuiper Belt, you don't see red objects and blue objects. So it suggests that that maybe they don't come from the Kuiper Belt. Maybe they come from somewhere else.
They are not evenly distributed, like maybe they come from one of two places.
Yeah, or maybe there's some process which is related to their composition which preferentially selects them. And there's this whole other group of objects out there. The Kuyper Belt is part of this set of objects we call trans Neptunian objects, basically anything out there past Neptune. And in that group of stuff, there's a group of objects called Plutinos, which are basically the category of objects that Pluto is in. You know, dwarf planets out there really far in the Solar System, and those things tend to have interesting colors. Like you remember when we did that flyby of Pluto. One of the big shocks was, frankly, how interesting Pluto was to look at.
Wow, are we sorry we downgraded it? Now They're like, oh, you're kind of cooler than we thought. We're sorry we kicked you out of our club.
Yeah.
I think that's what happens when you kick somebody at your best friends club and then you discover they actually really talented and you wish you had the stated friends with them. That Pluto has these really interesting features. It's really interesting colors, and it has this heart shaped pattern on it. It's a pretty beautiful planet. Actually, non planet, non planet, thank you very much, is a dwarf planet, and a lot of these plutinos out there have interesting colors, and so those things tend to have both red and blue colors. So it might be that these centaurs used to be plutinos. They used to be objects out there past Pluto and somehow got knocked inwards by some process we don't understand.
Now, can I actually see a space hunt centaur with my naked eye? Like, if I look at into the night sky, is it possible that I might see one going by?
No, there tend to be further out and they're too small, so we definitely need a telescope to see one, the same way that you couldn't see asteroids with your naked eye. And asteroids are sometimes even bigger than space centaurs and closer in. So if you see one with your naked eye, it means we're in trouble. Una, run away to Mars maybe, yeah, quick build that ship?
All right? Well, that is what a space centaur is. It's a sort of a half asteroid, half comet, but not really. It makes just sort of like a fuzzy object that falls in between the two.
And so we see that the stuff out there in the Solar System can't be nicely categorized into little bins that make sense. There's stuff out there that you know, might be a planet, might be a star, might be a dwarf planet. But there's an incredible variety of stuff out there for us to identify and to learn from.
Yeah, I think the cool thing is that there are still things out there, even in our Solar System that kind of defy definition or that still kind of surprises or still has this talking about what's out there and how it all came to be.
Yeah, and the far reaches of the Solar System are not very well explored. There's trans Neptunian objects, this stuff out there past Pluto is too far for us to see most of it, and we haven't sent very many probes, and so we're constantly surprised whenever we learn about them. And I think there are a lot more surprises out there waiting for us. And you know, even further out the Orc Cloud. Remember that's something we've never are actually seen, is just theoretical, and what it's just theoretical That means there are definitely surprises waiting for us.
Oh yeah, what could there be there could be interesting new things, and maybe some of our listeners could discover.
One day armies of elves waiting to take back the solutions.
Yeah yeah, what do you call a half common half planet, Daniel, or a half moon half planetoid.
I call it an ambush waiting to happen.
I call it a future Nobel prize for somebody that's listening to this. All right, Well, the next time you look up at the night sky, think about it. There might be a centaurs out there, or even new undiscovered objects that you could name or at least fantasize about naming.
And please be responsible with your future astronomical namings because we might have to cover it on the podcast.
Yep. All right, Well, we hope you enjoyed that. Thanks for joining us, See you next time.
Thanks for listening. Remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact, but the people in the dairy industry are That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. House US dairy tackling greenhouse gases. Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last Sustainability to learn more.
There are children, friends, and families walking, riding on passing the roads every day. Remember there real people with loved ones who need them to get home safely. Protect our cyclists and pedestrians because they're people too. Go safely California from the California Office of Traffic Safety and Caltrans.
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