Daniel and Kelly’s Extraordinary Universe - Are there centaurs in outer space?

Episode Date: December 24, 2020

Centaurs are real, but not on Earth. Daniel and Jorge talk about the weird objects astronomers call a "space centaur" Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

This is an I-Heart podcast. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, everything changed. There's been a bombing at the TWA terminal. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of Law and Order Criminal Justice System

On the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, luckily, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone.

Hold up. Isn't that against school policy? That seems inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hi, it's Honey German, and I'm back with season two of my podcast. Grazias, come again. We got you when it comes to the latest in music and entertainment with interviews with some of your favorite Latin artists and celebrities. You didn't have to audition? No, I didn't audition. I haven't auditioned in like over 25 years.

Oh, wow. That's a real G-talk right there. Oh, yeah. We'll talk about all that's viral and trending with a little bit of cheesement and a whole lot of laughs. And of course, the great bevras you've come to expect. Listen to the new season of Dresses Come Again on the Iheart Radio app, Apple Podcast,

or wherever you get your podcast. 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'd be in the night sky, you know, night with a cake. Sir Jorge, that is a terrible joke. Hi, I'm Jorge. 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 Jorge Explain the Universe, a production of IHeart Radio. 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? There's always 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, and there's a pretty big diversity out there because it's not just suns and planets out in space floating out there in 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 dwarves. That's all that's left. The dwarves 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 as 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 where you might argue like, hmm, 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 of 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. Today 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 write around in. Well, that is an ancient rivalry, unicorns versus centaurs.

They do not get along. Really? Oh, man. Can you have a space centaur with a horn? Where would the horn go? Exactly. Space uni centaur. Would it go on the forehead of the guy or the woman?

Where else would it go? I don't know. I guess it could come out of their chest. Yeah, exactly. I have a lot 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 explained the universe of fantasy creatures. But yeah, there is such a thing as a space centaur. 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 obliqually when we're 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 would dive into it in a whole episode. They thought you were kidding. 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 20 minutes before we started. 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 do you think are awkward versus right on? Well, I would estimate that you would place at about 95% 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 danielanhorpe.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 phenomenon 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 operator museum where villagers can engage 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 Iraqi objects between Jupiter and Neptune. A space centaur sounds like a constellation, maybe near 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, say Mars, for example. So I don't know about you, but I feel like we got exceptionally creative answers this week.

A Tesla? 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 writing science fiction 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. 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 as we 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 a few moons. 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 grips with this incredible number. variety of stuff by giving them all names that describe roughly what they do. But some of these names are like anchored in history because they come from very early observations.

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 unicorns versus centaurs? Asteroids versus comets? No, asteroids and comets get along. sometimes they mix and form space centaurs or space mermaids oh my goodness that's the next level space 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 with their 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 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 is 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 was 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 it 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 sky. Exactly. And 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 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 1800s, we had already seen 10 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. In science papers from like the 1800s, 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. He'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're also important differences between planets and asteroids. It's not just a difference of size? Like, I would think it would 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. it's moving sort of like a planet. But then we found that Pluto was 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's an enormous number of these things. These things are called trans-Neptunian objects, and some of them are called Plutoids or plutonos, but there's a huge number of these things out there.

And if you said Pluto's a planet, then you'd have to call them all planets, and, you know, planets have a historically important name. You know, like we 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. Sounds 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 over friends, best friends. And it's so confusing sometimes. There you go, exactly. So then what was the rationale or what was the official excuse? Did they go by size?

The long saga of the definition of 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 1800s, we had about 10 of them. And then it rapidly cranked up. We had, like, discovered a thousand asteroids by the early 1900s. And by now we know that there are many, many of these things. They're 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. Jupiter has its orbit, right? 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. Yes, 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 99% of the stuff in the solar system is the sun and of that remaining 1% Jupiter is most of it. Jupiter is like 99% of that 1%. 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 half are comets, which we'll get into in a short bit. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal.

Apparently, the explosion actually impelled metal, glass. The injured were being loaded into ambulances, just a... chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and Order Criminal Justice System is back. In Season 2, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop.

Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Well, wait a minute, Sam, maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone.

Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor, and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet.

So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Your entire identity has been fabricated. Your beloved brother goes missing. without a trace. You discover the depths of your mother's illness the way it has echoed and reverberated throughout your life, impacting your very legacy. Hi, I'm Danny Shapiro. And these are just a few of the profound and powerful stories I'll be mining on our 12th season of Family Secrets. With over 37 million downloads, we continue to be moved and inspired by our guests and their courageously told

stories. I can't wait to share 10 powerful new episodes with you, stories of tangled up identities, concealed truths, and the way in which family secrets almost always need to be told. I hope you'll join me and my extraordinary guests for this new season of family secrets. Listen to Family Secrets Season 12 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, Daniel, we're talking about space mermaids. Unicorns, man, unicorns. Space unicorns?

I guess maybe more like Space Pegasus, too. That could be pretty cool. They're like half birds, half horses, right? Yeah, or what about griffins? Are those like half birds, half lions, right? Those would be cool. Space Gryphins. Space hippogriffs.

That's the next level. That's right. 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 500 kilometers. The biggest one called Vesta is like 500 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? You might be a centaur. Oh, I see. It's like a location. It's like 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. Comets 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 a huge collection of rocky and icy objects. So that's the second key. Comets come from deeper out, either the Kuiper Belt or the Orch 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. The 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 Khyber Belt or the Orch 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 geologists talk about ice. Like they talk about the ice giants of nepottings. 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 on that, 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 500 kilometers wide. They're like 5 to 25 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 eventually. 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 correct, that there 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 out.

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 their unicorns and another solar systems, mermaids? That would be epic. Yeah, I want to read a book called exo mermaids. That would be pretty cool. Exo 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. Wasn't exomermy. It 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 like good pictures as it was on its way out. So there's still a lot of questions about what exactly Omuamua was. But most likely it was something from another solar system's equivalent of the orc 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 can just barely detect the planets, which are these huge masses. So we're very far from being able to see exo asteroids or exo comets 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 form deeper out and they just haven't gathered together into larger objects. And Neptune tends to keep these things small. Like 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 25 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 those are asteroids and comets. 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 have belly buttons, Daniel. Depends on how they are born, a deep mystery of science. Or do they have multiple belly buns? Well, you're sort of right.

A space centaur is half asteroid, 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, 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, partying 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 categorization so we can talk about stuff. You know, when you go to a meeting of astronomers and you say, I'm studying the planets.

You don't want to every time have to define what you mean by a planet. So you've 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's arguing about whether or not it counts as a space centaur 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 the space centaurs, they go out all the way to Neptune sometimes. So they're sort of like comets because they also have some of these comets. It's like you can see this 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 they really are sort of a mix of the characteristics of the two different things. So, wait, 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.

They 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 dust 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 could have their own gravity so they can sort of hold. hold onto these things. In fact, one of them is so big has its own rings system.

And like, you know, Saturn has rings. What? Yeah, there's this one centaur. It's called Chariqlo. And it's 300 kilometers wide. It's the biggest known centaur. And it orbits between Saturn and Uranus, and it has rings around it.

That's how big it is. It has its own gravity. Wow. What do you call the moon of a centaur, Daniel? I'm going to have to defer to the official astronomy naming department. Like a ferry, a space ferry? I think so, yes, a nymph maybe. A space nymph, there you go.

All right, so it's like it has an entourage. It's not just a 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. But 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 studied. There's only like 250 of them that have actually been identified, but we can only really see the bigger ones. So the estimates range from like 40,000 of these things to there might be 10 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 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. They're cross over the orbits of the giant planets.

Sometimes they're further out than Jupiter. Sometimes they're closer in than Jupiter. That sort of makes them more like a comet. But then again, they're 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. I see. So I guess this is the kind of argument that astronomers would have at 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 comet. So that's why they came up with a 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. Seven 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. Does it matter if you cross Neptune or if you cross Jupiter?

And these are just like totally arbitrary, but conflicting definitions of what a space centaur is. Wow. 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.

to particle fizzes, I guess. All 5% 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. December 29th, 1975, LaGuardia Airport. The holiday rush. Parents hauling luggage, kids gripping their new Christmas toys.

Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal glass. The injured were being loaded into ambulances. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and order criminal justice system is back.

In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Well, wait a minute, Sam, maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her.

Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor, and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him?

Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Your entire identity has been fabricated. Your beloved brother goes missing without a trace. You discover the depths of your mother's illness,

the way it has echoed and reverberated throughout your life, impacting your very legacy. Hi, I'm Danny Shapiro. And these are just a few of the profound and powerful stories I'll be mining on our 12th season of Family Secrets. With over 37 million downloads, we continue to be moved and inspired by our guests and their courageously told stories.

I can't wait to share 10 powerful new episodes with you, stories of tangled up identities, concealed truths, and the way in which family secrets almost always need to be told. I hope you'll join me and my extraordinary guests for this new season of Family Secrets. Listen to Family Secrets Season 12 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, Dana, we're talking about space centaurs, which are, are a mix of asteroids and comets. They're like, you know,

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 there's 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've 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 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 like 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 the 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 like philosophical differences about how you categorize this stuff. that I think we're 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 there's sort of a naming war for those, too.

That's true. Yeah, exactly. The naming centaur wars. All right. Well, step us through here. 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 centaurs.

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. They look like pinpoints, but like a red pinpoint and a blue pinpoint sometimes. 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 pinprick. And that's the limitation of our knowledge about space centaur so far. We basically just see them as pinpricks in telescopes because we've never done a close-up fly-by. 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 like how the solar system was formed. And we try to compare what that predicts to what we actually see out there in space. And when there's something we don't understand, that tells us that something in our model is wrong. And so we're interested in like, where do these space centaurs form? Do 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 bi-colored. There aren't red and blue objects out there in the Khyper belt. Wait, if something's red and blue, would it be purple? Can there be purple centaars, if not purple dragons? Purple dragons. No, we mean that the Kuiper Belt doesn't necessarily have like 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 Khyper belt, you don't see red objects. and blue objects. So it suggests that maybe they don't come from the Kuiper Belt, maybe they come from somewhere else. Like maybe 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 Kuiper Belt is part of this set of objects we call trans-Neptunian objects, basically anything out there past Neptune. And in that group,

both 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 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 out of your best friends club and then you discover they actually really talented and you wish you had to stay friends with them. Now, 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. It's 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 the 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 out 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 you would 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. Run away. Run away to Mars, maybe. Yeah. Quick, build that ship. All right. Well, that is what a space centaur is.

It's sort of a half asteroid, half comet, but not really a mix. 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 makes 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 us 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. This trans-Neptunian objects, the 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 even further out, the Orch Cloud, remember, that's something we've never actually seen.

It's just theoretical. And when it's just theoretical, that means there are definitely surprises waiting for us. Wow, yeah. What could there be? There could be interesting new things that maybe. Some of our listeners could discover one day. Armies of elves waiting to take back the solar system. Yeah.

Yeah, what do you call a half comet, 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 listening to this. All right, well, the next time you look up at the night sky, think about it. There might be centaurs out there or even new undiscovered objects that maybe 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. And 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. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage,

kids gripping their new Christmas toys. Then everything changed. There's been a bombing at the TWA. terminal, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious.

Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, luckily, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Hold up. Isn't that against school policy? That seems inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast.

Here's a clip from an upcoming conversation about how to be a better you. When you think about emotion regulation, you're not going to choose an adaptive strategy which is more effortful to use unless you think there's a good outcome. Avoidance is easier. Ignoring is easier. Denials easier. Complex problem solving takes effort. Listen to the psychology podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. This is an IHeart podcast.