Speaker 1: Hey, Daniel, did you ever want to be an astronaut? Well, yes,
Speaker 1: but I didn't because I'm terrified of the danger and
Speaker 1: the adventure. Yeah, I'm not ready to travel in the
Speaker 1: space until it's safe and routine. Yeah, it is pretty
Speaker 1: dark and scary out there, But isn't that kind of
Speaker 1: the point of space exploration to go out there and
Speaker 1: discover and find new things hiding in the darkness. Yeah,
Speaker 1: and I want other people to go out there take
Speaker 1: those risks, and then I can just read about it
Speaker 1: in the newspaper. Hi am or Handmay, cartoonist and the
Speaker 1: creator of PhD Comics. Hi. I'm Daniel Whitson. I'm a
Speaker 1: particle physicist, and I'm a stay at home adventurer of
Speaker 1: the mind couch Explorer. I'd like to explore this vast
Speaker 1: universe from the comfort of my office. But welcome to
Speaker 1: our podcast, Daniel and Jorge Explain the Universe, a production
Speaker 1: of I Heart Radio, in which we take you on
Speaker 1: an exploration of all the amazing, crazy, monkers, beautiful, nasty, crazy,
Speaker 1: weird things in this universe. Did I say crazy twice?
Speaker 1: That's because the universe is that crazy. It's double crazy.
Speaker 1: I feel like the things we're learning in science every year,
Speaker 1: every decade, every generation are crazier than the things we
Speaker 1: learned before. It's not just that we're learning more, but
Speaker 1: the stuff we're revealing is just more bonkers than anything
Speaker 1: we could have imagined. Don't you feel that way? Well,
Speaker 1: do you think it's crazier than what we thought it
Speaker 1: was before? You know, is it crazier than Greek gods
Speaker 1: and Norse mythology? Well, I think it's maybe less creative,
Speaker 1: but it's definitely crazier. Every generation has had to absorb
Speaker 1: ideas which were very difficult to swallow because they completely
Speaker 1: conflict with our view of the world. You know, the
Speaker 1: universe is expanding, there is no sense of location and time.
Speaker 1: You know, things are fundamentally random. Space curves like these
Speaker 1: are hard things to get your mind around, and they
Speaker 1: get harder and harder as we discover them. Yeah. We
Speaker 1: are not the center of the universe, and the universe
Speaker 1: is not like what we see around are where we are. Yeah,
Speaker 1: and every time we look out into space we discover
Speaker 1: new stuff, weird stuff. Places we thought were empty turned
Speaker 1: out to be filled with interesting, fascinating, weird kinds of matter.
Speaker 1: M Yeah, because that's kind of the history of humanity
Speaker 1: and science. Right, Like, we look around and we assume
Speaker 1: that the whole universe is kind of like where we're at. Right.
Speaker 1: We thought the world was flat because everything seems flat
Speaker 1: around us, And we thought that the Earth was the
Speaker 1: center of the universe because everything seems to provolve around this.
Speaker 1: But then as we learn more that we learn that
Speaker 1: there are more and more different things out there. We
Speaker 1: keep learning that the assumptions we make, that the generalizations
Speaker 1: we make about what we learned here, cannot be applied everywhere.
Speaker 1: And that's the exciting part. That's the moment of discovery,
Speaker 1: when you realize, oh, I thought the universe was this way.
Speaker 1: It turns out it's actually totally different in a way
Speaker 1: I never imagine. We're intellectually maturing as a species by
Speaker 1: discovering our universe and coming to grips with it. And
Speaker 1: it's not always the way we liked it, but it
Speaker 1: turns out to be quite fascinating to the other program
Speaker 1: will be tackling one such idea that you know, maybe
Speaker 1: a lot of people even today think is true, but
Speaker 1: actually it turns out to be much more complex than that.
Speaker 1: That's right, that darkness out there is more filled with
Speaker 1: interesting stuff and rocks than you could have ever imagined. Yeah,
Speaker 1: stuff that's out there hiding in the darkness, other worlds
Speaker 1: out there looking at ours and wondering what would it
Speaker 1: be like to be so close to a nice, warm,
Speaker 1: toasty star. Yeah. So today on the program, we'll be
Speaker 1: tackling the question are there planets without stars and not
Speaker 1: just a movie stars? Right? We're talking about are there
Speaker 1: places in the universe then don't have a son or
Speaker 1: a star near them? I like the one you asked though, Like,
Speaker 1: are their planets out there with only being C list actors?
Speaker 1: That's right? Where everyone uh it only has five seconds
Speaker 1: of fame. You can only be in one movie and
Speaker 1: then your career is over. It's like turn limits for
Speaker 1: for Hollywood actors. That's great, and then that'd be great
Speaker 1: if we got rid of celebrity culture in our society. Yeah, well,
Speaker 1: that won't appeal to any of our celebrity listeners, you know.
Speaker 1: So Hey Brad Pitt, don't worry. You can still come
Speaker 1: on the program. But apparently it works if you If
Speaker 1: you speak badly about somebody don't want to come on
Speaker 1: our show, then that's true. To defend themselves, maybe to
Speaker 1: grab any kind of publicity they can. That's true. Stay
Speaker 1: tuned for our episode in which science fiction authors come
Speaker 1: on the show and respond to our critiques. And when
Speaker 1: we're thinking about the broad universe, you know, you are
Speaker 1: used to thinking about your planet is having one very
Speaker 1: important feature, which is the on And every time you
Speaker 1: think about a planet, you imagine, well, planets form around stars, right,
Speaker 1: and so it's a bit mind bending to imagine that
Speaker 1: the universe might be different. Yeah, a lot of people
Speaker 1: might be surprised to learn that not every planet out
Speaker 1: there is centered around the star. You may be shocked
Speaker 1: to discover that rogue planets are not that rare. That
Speaker 1: the universe may be chalk filled with these floating dark bodies. Yeah,
Speaker 1: and that's the official physics name for them, right, like
Speaker 1: a planet without a star. It's officially called a rogue planet. Yes,
Speaker 1: but you will not be surprised to discover there is
Speaker 1: some controversy about what exactly gets called a rogue planet.
Speaker 1: Oh wow, physicists arguing about what to name something that's
Speaker 1: so rare, not only arguing about whether something is a
Speaker 1: good name, but like what exactly falls into this category?
Speaker 1: You know, the whole Pluto, like is it a planet?
Speaker 1: Is it not a planet? Thing? That's this same controversy
Speaker 1: large interesting because I guess everything is sort of being
Speaker 1: pulled by every star in the universe, So technically there
Speaker 1: there isn't this a planet that's not being pulled by
Speaker 1: a star. I like that. You're sort of saying every
Speaker 1: planet is part of a sum solar system, even if
Speaker 1: it's sort of distant from its star. Right, Well, technically, right,
Speaker 1: don't all solar systems sort of overlap with each other?
Speaker 1: Technically because the force of gravity is infinite has infinite reach. Yeah,
Speaker 1: that's true. The force of gravity is infinite, but at
Speaker 1: some point the force of gravity from these stars is
Speaker 1: basically negligible and there's essentially no effect on these planets,
Speaker 1: and they're more affected. Yeah, negligible, They're more affected by
Speaker 1: the mass of the galaxy. So I think the distinction
Speaker 1: is are you orbiting a star or are you orbiting
Speaker 1: the center of the galaxy? All right, Well, I was
Speaker 1: a little surprised to find out that there are road
Speaker 1: planets out there, and that there are apparently not just
Speaker 1: a few of them. But we were wondering how many
Speaker 1: people out there knew the same fact that there are
Speaker 1: planets out there in space without stars. So I walked
Speaker 1: around campus a you see, Irvine, and I asked folks
Speaker 1: what they thought and if they had a guess for
Speaker 1: how many rogue planets there might be in the universe.
Speaker 1: To think about it for a second, how many planets
Speaker 1: out there in the universe? Would you, guys are out
Speaker 1: there floating without a star. Here's what people had to say.
Speaker 1: I have no clue how many there are. My guests
Speaker 1: understanding from what I think I know is that they're
Speaker 1: by one way or another of something flying by the
Speaker 1: end up injected from the star that they'reth I have
Speaker 1: not do you think does exists? I don't think. I
Speaker 1: can't imagine that that would be not true, honestly, like
Speaker 1: a lot of just like ten, I would have no
Speaker 1: idea how to give a number, Um I would I
Speaker 1: would actually have to say probably a lot, just because
Speaker 1: gravity is so you can get a star really close
Speaker 1: to another set of planets and then it throws them
Speaker 1: off in space. So probably a lot, probably, I think.
Speaker 1: So you think it's like seven or like a billion? Jeeus? Um, Well,
Speaker 1: in a in a big universe, I don't know if
Speaker 1: we could count. No, I think every planet. I think
Speaker 1: interested pretty good mix of reactions. Yeah, a lot of
Speaker 1: open minds. I love the people who say the universe
Speaker 1: is so big you can never say no, you can
Speaker 1: never say that something doesn't exist. I think that's a
Speaker 1: great attitude because technically, in an infinite universe, anything can happen, right,
Speaker 1: and anything is happening. Yeah, in an infinite universe, everything
Speaker 1: that can happen eventually will happen and is happening somewhere.
Speaker 1: So it's a good attitude. Now, we don't know the
Speaker 1: universe is infinite, but it's definitely pretty big right somewhere
Speaker 1: out there. There's a version of this podcast in which
Speaker 1: you and I are the A List celebrities. That's not
Speaker 1: this version. What are you saying? I don't I'm confused.
Speaker 1: I think we're run out of letters letters. That's right
Speaker 1: with the Triple A. We're the Triple We're Triple A celebrities,
Speaker 1: which sounds good, but really, welcome to the minor the
Speaker 1: Ego podcast, folks. Yeah, so, um, but people seem sort
Speaker 1: of skeptical. I mean, some people said yes, but it
Speaker 1: sort of seemed like yes, probably, but probably it's probably
Speaker 1: not very common, that's right, and it's immediately a fascinating question.
Speaker 1: It's the kind of thing you might not ever think about.
Speaker 1: You think, oh, well, planet is of course they form
Speaker 1: around stars, and that's reasonable because stars form from the
Speaker 1: gravitational collapse of stuff, and plants do the same thing,
Speaker 1: and so you should imagine they formed together. They're probably
Speaker 1: associate with each other. You probably don't ever think that
Speaker 1: there are dark bodies floating out there in between the stars.
Speaker 1: But as soon as somebody suggested to you, then you
Speaker 1: have to wonder, well do we know, how do we know?
Speaker 1: Have we looked? Could we see them? And immediately it's
Speaker 1: a question you need to know the answer to. Yeah,
Speaker 1: because if it's a lot, then they would be pretty
Speaker 1: uh interesting, I guess, or dangerous because what if one
Speaker 1: of them hits us? Yeah, it's a little bit dangerous.
Speaker 1: But also it just changes sort of your your view
Speaker 1: of the universe. I mean, what if there are more
Speaker 1: rogue planets out there than non rogue planets, then your
Speaker 1: whole view of like what is a planet has to
Speaker 1: all of a sudden change from oh, they're all around
Speaker 1: stars to well, my sense of a planet is unusual
Speaker 1: is a typical? Oh I see, it could be that
Speaker 1: our kind of planet is the minority. Yeah, exactly, Just
Speaker 1: like we discovered that our kind of matter is a
Speaker 1: small fraction of all the matter in the universe. All
Speaker 1: of a sudden, things we thought were typical are now weird.
Speaker 1: It'd be like discovering their more continents out there. Or
Speaker 1: you know, you grow up in your family eats a
Speaker 1: dinner a certain way, and then you go to a
Speaker 1: friend's house you discover, oh man, my family is weird.
Speaker 1: We are and we don't use utensils at home or
Speaker 1: whatever it is. You know, it's it's maturing in that
Speaker 1: same way, right, It's expanding your horizon and your idea
Speaker 1: of the universe. And that's why this is such a
Speaker 1: fun opportunity to learn something new about the universe. All right,
Speaker 1: so let's get into it. Daniel Wood exactly is a
Speaker 1: rogue planet. Right, So let's begin with technical definitional stuff
Speaker 1: that we could argue about easily for half an hour.
Speaker 1: And and and very importantly, is there a first rogue
Speaker 1: planet called rogue one? Well, the movie rights for that
Speaker 1: one I've already been locked up, unfortunately. Yeah, Well they're
Speaker 1: not definitely not making a sequel of that one. I
Speaker 1: liked it. I liked it, but you know, Rogue two's
Speaker 1: agent is not exactly getting a lot of traction in Hollywood.
Speaker 1: But a rogue planet is a planet that's not orbiting
Speaker 1: a star. And you said earlier, and you're right that
Speaker 1: every planet feels the gravity from every star in the galaxy,
Speaker 1: but you have to look at its motion, like the
Speaker 1: motion of the Earth is that we are orbiting our star.
Speaker 1: We're moving around our star. But if we were a
Speaker 1: rogue planet, then our primary motion would just be around
Speaker 1: the center of the galaxy. Would be the same category
Speaker 1: as the stars, like our star orbits the center of
Speaker 1: the galaxy. It's a planet that's not sort of trapped
Speaker 1: by the gravitational well or pool of a star. Yeah,
Speaker 1: we liked to in goo a Solar System as an
Speaker 1: object because it's gravitationally bound that the dominant gravitational force
Speaker 1: on every object in the Solar System is the Sun.
Speaker 1: So it's like the Sun has its own little neighborhood
Speaker 1: in which it's gravity is more powerful than any other gravity.
Speaker 1: Or I guess maybe not not just that it's more powerful,
Speaker 1: but it's powerful enough to to sort of trap things
Speaker 1: in its vicinity. Yeah, it's a stable to let it
Speaker 1: go exactly. But you know, the galaxy is big, and
Speaker 1: there are a lot of stars, but they're not that many,
Speaker 1: and so there's a lot of room out there between stars. Remember,
Speaker 1: we're you know, light years away from the nearest star,
Speaker 1: which makes a huge amount of space for stuff to
Speaker 1: be floating between the stars. Oh, I see, So there's
Speaker 1: a lot of room for you to be out there
Speaker 1: without falling into the you know, the trap of the
Speaker 1: gravitational pool of a star. Yeah, if you mapped the
Speaker 1: Milky Way onto Earth, for example, you know, you have
Speaker 1: like one house here in Los Angeles and another house
Speaker 1: like in Kansas, and another house like in New York City,
Speaker 1: and there'll be a lot of room between those that
Speaker 1: you could rogue around it. Yeah, you can have a
Speaker 1: rogue cabin in the woods and never have to get
Speaker 1: close to anybody. And I guess more importantly, you could
Speaker 1: be so far away from my house and your house
Speaker 1: in Kansas, Dad, you wouldn't feel the need to sort
Speaker 1: of go visit. Yeah, and you could largely ignore them.
Speaker 1: You know, those stars would just be other slightly more
Speaker 1: bright stars in the sky, and you wouldn't feel their
Speaker 1: gravitational pull strongly enough to get sucked into one of them.
Speaker 1: All right, So then what's the definition then that it's
Speaker 1: it's a planet, meaning like a ball of stuff? Is
Speaker 1: that what it means? What is exactly a planet? Yeah?
Speaker 1: Well that's where it gets tricky, right. Um. These are
Speaker 1: either things that were formed in other solar systems and
Speaker 1: then ejected, or you could also think about stars that
Speaker 1: never sort of got started, like failed stars. You know
Speaker 1: what if a star never sort of turns on because
Speaker 1: it's not big enough to burn, is that a rogue
Speaker 1: planet or is that a failed star? Is a heated
Speaker 1: debate in astronomy, But both of those things are out
Speaker 1: there well in a way sort of Jube, isn't Jupiter
Speaker 1: also kind of a failed star? Like it could have
Speaker 1: been a star but it wasn't. Yeah, And if Jupiter
Speaker 1: had formed far enough away from the Sun on its own,
Speaker 1: if it was like the center of its own little
Speaker 1: gravitational neighborhood, we would call it a sub brown dwarf star.
Speaker 1: But because it formed around our star, we call it
Speaker 1: a planet. And so there's a lot of energy spent
Speaker 1: in astronomy arguing about these names and definitions. And wait,
Speaker 1: you're saying that if Jupiter wasn't in our solar system,
Speaker 1: if it was out there, it would be considered a
Speaker 1: star even though it's not burning. Yeah, there's a whole
Speaker 1: category of stars called brown dwarfs and sub brown dwarfs
Speaker 1: that are just not big enough to ignite fusion and
Speaker 1: to burn and to glow. But why still call them
Speaker 1: a star if they're not ignited? I'm burning, see what
Speaker 1: I mean. People have strong feelings about this, like you do.
Speaker 1: Apparently in your mind you think, you think, if it's
Speaker 1: got to be burning to be a star, right, Well,
Speaker 1: other people think, oh know, it's a failed star. That's
Speaker 1: a kind of star, all right, So that's kind of
Speaker 1: the definition. It's a ball of stuff, or maybe the
Speaker 1: definition is kind of fuzzy, but generally speaking, a rogue
Speaker 1: planet is a ball of stuff. It could be gas.
Speaker 1: Could be rock too, right, rocks or gas or you know,
Speaker 1: it's compressed matter kind of um just to make it
Speaker 1: different than a cloud. And it's floating out there in space,
Speaker 1: not in the orbit of a star. Whatever that could mean.
Speaker 1: That's right, it's a it's a dense blob of stuff.
Speaker 1: Primarily orbiting the center of the galaxy instead of orbiting
Speaker 1: another star. All right, let's get into how we can
Speaker 1: see them even though it's dark out during space and
Speaker 1: how many there are out there in the universe. But
Speaker 1: first let's take a quick break. All right, I know
Speaker 1: there are floating planets out there in the universe in
Speaker 1: our galaxy that don't have a star. They're called road planets,
Speaker 1: and there might be a lot of them. So first
Speaker 1: of all, I guess, how do we even see them
Speaker 1: if it's they're not burning bright and they're not near
Speaker 1: a star for them to shine, Um, how do we
Speaker 1: know they're there? It's tricky, right, These are dark objects.
Speaker 1: They are not shining, they're not emitting light, and as
Speaker 1: you say, they're not close enough to any star to
Speaker 1: reflect light like like exoplanets are. So it's not easy
Speaker 1: to spot them, which is why for a long time
Speaker 1: we didn't even know that they existed. Um, but there
Speaker 1: are two ways to see them. One is you get
Speaker 1: really lucky, and one is close enough that we can
Speaker 1: see them in the infrared. Remember, these things are not burning,
Speaker 1: so they're not shining visible light, but they still have
Speaker 1: some heat to them and everything in the universe that
Speaker 1: has a temperature also radiates some energy, usually in the infrared,
Speaker 1: and so sort of glowing in the infrared. And we
Speaker 1: have infrared telescopes, I see, because we I think we're
Speaker 1: used to thinking of like asteroids and things out there
Speaker 1: in spaces being cold, but you could have, for example,
Speaker 1: like the Earth is kind of warm by itself. The
Speaker 1: Earth is kind of warm. And even if we were
Speaker 1: ten or fifty kelvin. And I want to give props
Speaker 1: to the person out there who wrote in to remind
Speaker 1: me that it's not degrees kelvin, it's just kelvin. But
Speaker 1: even if we were just ten or fifty kelvin, we
Speaker 1: would still radiate. Everything that's above absolute zero radiates some energy.
Speaker 1: It's called black body radiation. Oh, I see. It sort
Speaker 1: of shines in the infrared. Yeah. And there's a telescope
Speaker 1: called the Wise telescope w I S E, which is
Speaker 1: really good at seeing this stuff, and it's really good
Speaker 1: in the infrared. And so if it's close enough that
Speaker 1: you can spot them directly with the Wise telescope, but
Speaker 1: it has to be pretty close. So like if our
Speaker 1: son suddenly went out and there was no more light
Speaker 1: in our solar system, you could still maybe see the
Speaker 1: Earth and all the other planets. Yeah, you could, precisely.
Speaker 1: And we do this to study other solar systems. We
Speaker 1: look at them in the visible light and we also
Speaker 1: look at them in the infrared to try to get
Speaker 1: a glimpse for like, what is the stuff out there
Speaker 1: that's not blowing. It's still there, it's giving off different
Speaker 1: kinds of radiation. So we have lots of different ways
Speaker 1: of looking at the sky. The infrared, X ray, radio,
Speaker 1: These are all just different kinds of light though. They're
Speaker 1: all just different parts of the electromagnetic spectrum. But different
Speaker 1: things out there glow in different parts of these spectrums.
Speaker 1: So the most direct way is to look for them
Speaker 1: in the infrared. But they have to be really close by,
Speaker 1: Oh I see, because otherwise it would be too faint
Speaker 1: to see them. Yeah, Because these things are small and
Speaker 1: pretty faint, and so they're pretty hard to spot. The
Speaker 1: best way to see these things is to look for
Speaker 1: a little star eclipse. What well, if you have a
Speaker 1: big dark object somewhere out there in the universe and
Speaker 1: it passes between you and a star, then what happens
Speaker 1: It blocks the light from that star momentarily like a
Speaker 1: one time eclipse. Yes, like a one time eclipse, one
Speaker 1: time ever eclipse, one time ever. Yeah. And so you
Speaker 1: can see these things if you very carefully watch all
Speaker 1: the stars in the sky and wait for a blip.
Speaker 1: But there's something really fascinating because you might expect that,
Speaker 1: like a star eclipse would dim the star, that it
Speaker 1: would go out for a minute and then come back, right,
Speaker 1: that's you'd expect, But this is really weird. Gravitational effect.
Speaker 1: If the rogue planet or whatever it is alien ship
Speaker 1: is big enough, then it has a gravitational lensing effect.
Speaker 1: It acts like a big lens in space. Because remember
Speaker 1: gravity is the bending of space. So gravity can change
Speaker 1: the direction of light. We'll just block the light, they'll
Speaker 1: bend the light. I mean that sort of happens here
Speaker 1: on Earth too when there's an eclipse, right, doesn't the
Speaker 1: light sort of go around the Moon when it's blocking
Speaker 1: the sign a little bit? It does a little bit. Yeah,
Speaker 1: And in this case it can actually enhance the strength
Speaker 1: of that star because it acts like a lens. It
Speaker 1: gathers more light and it focuses it all on the Earth.
Speaker 1: So what actually happens when you get a micro lensing
Speaker 1: event they call it, is that the star gets brighter,
Speaker 1: not just a darker or like darker and lighter. Yeah,
Speaker 1: it actually gets brighter. It gets enhanced, right, it gets
Speaker 1: amplified by this micro lensing, and so the very center
Speaker 1: of it is blocked out. But you're gathering light from
Speaker 1: nearby and focusing it onto the earth. You actually get
Speaker 1: more of the starlight when it goes by. It's an
Speaker 1: eclipse that makes it the start look brighter. Yeah, recisely.
Speaker 1: It's really fun. And the telescope to see these things
Speaker 1: has a really awesome name. It's called the OGLE telescope.
Speaker 1: I thought I thought it was already too much to
Speaker 1: have a wise telescope. W I s e this one.
Speaker 1: I want to look at things called the OGLE if
Speaker 1: you want to sit on the couch and ogle the universe,
Speaker 1: and you do it using the optical Gravitational Lensing Experiment OGL. Wow,
Speaker 1: you guys probably pop some champagne when you came up
Speaker 1: with that name. So those are the two ways you
Speaker 1: can see him. You can see them either through micro
Speaker 1: lensing or anti eclipses or directly through the infrared. And
Speaker 1: so what do we know about them? Do we know
Speaker 1: are they sort of round like our planets necessarily, or
Speaker 1: do they look like giant asteroids or what do we
Speaker 1: expect them to look like? Yeah, we expect that they're
Speaker 1: mostly round because anything that's big enough gravity will make
Speaker 1: it round. You know, gravity is powerful, and if you've
Speaker 1: got a bit that's sticking out, eventually it's going to
Speaker 1: roll down. And so you have something that's big enough
Speaker 1: to have strong gravity, it's going to get around. Oh,
Speaker 1: I see, And you expect these to be big, right,
Speaker 1: I guess if you're If you're calling them planets, there's
Speaker 1: a certain size associated with that name, isn't there? Like
Speaker 1: Pluto got demoted because it wasn't big enough. Yeah, But
Speaker 1: the really amazing part is that probably there's a whole
Speaker 1: spectrum of sizes, from like things bigger than Jupiter down
Speaker 1: to Earth size things down to just rocks, and the
Speaker 1: number is probably inversely proportional to the size. So there
Speaker 1: are a certain number of Jupiter sized ones, and they're
Speaker 1: probably more Earth sized ones, and then probably like a
Speaker 1: xillion times more just box out there. But at some
Speaker 1: point they're just called rocks. You wouldn't call them planets, right,
Speaker 1: At some point they're called planets and then dwarf planets,
Speaker 1: and then yeah, just comets or rocks or dust. Right,
Speaker 1: and you know, some of these things have come to
Speaker 1: our solar system. Remember Omama and the comment that came
Speaker 1: through UM in December. These are just rocks from other
Speaker 1: solar system that flew through our Solar system. Wow, there
Speaker 1: are Jupiter size planets out there, just floating in space,
Speaker 1: not being bound to any star, just doing their own thing.
Speaker 1: And that was the question when people first thought about this.
Speaker 1: They thought, are they out there? Let's go look for them,
Speaker 1: and so they started using these two approaches, and what
Speaker 1: they found sort of boggled the mind. Right, they found
Speaker 1: more than they expected. Yeah, they found that there's something
Speaker 1: like around one Jupiter sized rogue planet for every star
Speaker 1: in the Milky Way. So there's hundreds of millions of
Speaker 1: these Jupiter size rogue planets out there. Yeah, more like
Speaker 1: a hundred billion, yeah, because it's not about a hundred
Speaker 1: billion stars in the Milky Way. And a few years
Speaker 1: ago there was a really exciting result. Some people said
Speaker 1: that there might be like two to four Jupiter size
Speaker 1: rogue planets out there for every single star, so like
Speaker 1: hundreds of billions, and everybody was like reacted just the
Speaker 1: way you did, like what And then another experiment did
Speaker 1: some measurements and they came back to everybody, calm down.
Speaker 1: It looks like there's probably just about one jupiter size road.
Speaker 1: And I was like, that's still crazy. I mean, I
Speaker 1: was thinking like there might be ten in the whole galaxy.
Speaker 1: Turns out there's billions and billions of these things, and
Speaker 1: those are the Jupiter sized ones. The milky ways litter
Speaker 1: with these. Yeah, they're everywhere, and if as you go
Speaker 1: down the mass scale right like Earth size planets, there
Speaker 1: might be ten or even a hundred times as many. Wow,
Speaker 1: it's just traffic out there. It's pretty messages stuff. Nobody's
Speaker 1: cleaned up, right. We formed all these solar systems and
Speaker 1: that all the leftover base are just still out there.
Speaker 1: But you know, it gets more and more uncertain. As
Speaker 1: the size of the object we're talking about gets smaller,
Speaker 1: it's harder to see, and so we've seen fewer of them,
Speaker 1: so we're making more of an extrapolation with more uncertainty.
Speaker 1: We're in early days of understanding this, and in five, ten,
Speaker 1: fifty years we'll have a much better handle on it.
Speaker 1: But right now it's pretty uncertain. Are they going to
Speaker 1: keep on floating out there? Or will will all of
Speaker 1: these planets eventually kind of fall into a star. Think
Speaker 1: about what happens when a big Jupiter's eye planet approaches
Speaker 1: a star. It's not that easy to fall into orbit. Remember,
Speaker 1: orbit requires being in the right location, having the right direction,
Speaker 1: and the right velocity. Much more likely is that you
Speaker 1: come into a solar system and you just sort of
Speaker 1: like mess it up. Yeah, you perturb the gravitational, the
Speaker 1: nice cozy gravitational orbits of everybody that's been there for
Speaker 1: billions of years, and you make more rogue planets like
Speaker 1: you come in and you bust up a family. If
Speaker 1: a Jupiter sized planet came into our solar system, we
Speaker 1: would probably lose a planet or two. Well, I hope
Speaker 1: it's not Earth. They can take Pluto, Neptune. You know,
Speaker 1: we don't even we don't even care about those. Wow,
Speaker 1: they haven't even arrived yet. And you're and you're already
Speaker 1: at the negotiating table offering up our neighbors. What has
Speaker 1: urine has done for me lately? Oh? Come on, it's
Speaker 1: comic fodder. Urine is really I would give away Neptune first,
Speaker 1: I see it's less funny. I see you need you
Speaker 1: want you want to planet around you can make fun
Speaker 1: of it. Yeah, exactly, some some planet has to be
Speaker 1: the butt of all of our jokes. So okay, So
Speaker 1: it's not likely because they're if they're already floating out there,
Speaker 1: you know, careening through space, it's unlikely for them to
Speaker 1: stop at any particular start. They'll just kind of bounce
Speaker 1: around from solar system to solar system. It is possible,
Speaker 1: it's possible for our start to capture a new planet,
Speaker 1: and people wonder about the history of our Solar system,
Speaker 1: you know, like some of our planets have weird orbits.
Speaker 1: Is it possible they were captured? But if you just
Speaker 1: shoot a planet at a star, most of the trajectories
Speaker 1: will lead to it just being like whipped around and
Speaker 1: shot out into space and probably losing some of its planets.
Speaker 1: I guess. Then that gets us to the question of
Speaker 1: how these planets even formed. If they are not in
Speaker 1: a solar system, and they were, probably they can be
Speaker 1: captured by a solar sism. Where did they even come from?
Speaker 1: So let's tackle that question. But first let's take a
Speaker 1: quick break, all right, So where do rogue planets come from.
Speaker 1: Is there like a rogue planet factory somewhere? Is there
Speaker 1: a rogue nation of planets where all of these planets
Speaker 1: go rogue from their rogue nation. Well, it depends on
Speaker 1: how you define a rogue planet. There is a big
Speaker 1: population of them that were probably formed around a star,
Speaker 1: just like Earth and Jupiter and all of our planets.
Speaker 1: They were part of some big cloud out of gas
Speaker 1: and dust and rocks which coalesced to form a star
Speaker 1: and planets. But remember that's not like organized. Nobody planned
Speaker 1: our Solar system, and so in the early days of
Speaker 1: our Solar system, stuff was pretty chaotic. It's not like
Speaker 1: everybody had cleared it up and say, everybody in this
Speaker 1: lane become Earth and everybody over here. You had stuff
Speaker 1: sort of bouncing around more. It was more disorganized, and
Speaker 1: so stuff got ejected. So some planets that were formed
Speaker 1: in the early days of our Solar system probably got
Speaker 1: ejected are now out there and planets we have a
Speaker 1: lost brother out there or sister. Yeah, we almost certainly do.
Speaker 1: And it's almost certainly almost certainly we um. It's a
Speaker 1: fun question to ask, like what fraction of planets end
Speaker 1: up in stable orbits and what fraction get ejected? Um,
Speaker 1: And you know we're looking at our Solar system billions
Speaker 1: of years in. It's basically after everything has settled down,
Speaker 1: you know, in our Solar system, people think, for example,
Speaker 1: like Saturn and Jupiter might have once had different orbits
Speaker 1: that might have been in a different order because we
Speaker 1: had more things. Yeah, and that there was a third planet,
Speaker 1: another icy giant, which got ejected from the Solar system.
Speaker 1: Like you look at the organization of our Solar system
Speaker 1: for clues, and you're like, this looks weird. You know,
Speaker 1: would make more sense if this crazy thing happened. And
Speaker 1: that's how we ended up with this configuration of our planets. Oh. Interesting,
Speaker 1: that's right, because the Solar System didn't always look like
Speaker 1: the Solar System. No. And remember Earth had a massive
Speaker 1: collision with like a planet sized object which led to
Speaker 1: the formation of the Moon. Where did that thing come from? Well,
Speaker 1: probably our Solar system and so and now it's been obliterated. Okay.
Speaker 1: So so that's one way you can create a rogue
Speaker 1: planet out there in spaces. You it's born in a
Speaker 1: Solar System along with other planets, but then the other
Speaker 1: planets sort of get together and and kind of vote,
Speaker 1: vote that planet out. That's right, planet survivor. But you know,
Speaker 1: from that planets point of view, they're probably like, I
Speaker 1: never wanted to be in a solar system anyway. It's
Speaker 1: so much more exciting out here in the backwoods. I
Speaker 1: see much cooler out here. It is much cooler out there. Um.
Speaker 1: And it could also be, as we talked about earlier,
Speaker 1: that something comes by and perturbs and nice stable solar system,
Speaker 1: like a black hole comes near a solar system and
Speaker 1: perturbs it and sucks out some of the planets, or
Speaker 1: even just you know, another passing rogue planet. So solar
Speaker 1: systems are not that stable. So so those are rogue
Speaker 1: orphan planets I guess you could call um. Then you
Speaker 1: can also have like true road planets or like uh,
Speaker 1: independently formed road planets, feral planets, maybe we can say
Speaker 1: native planets. These are the ones that you were saying
Speaker 1: don't really count as a star, and they're called sub
Speaker 1: brown dwarf stars, and they're just clumps of matter that
Speaker 1: started to form together but didn't get enough to form
Speaker 1: enough gravitational pressure that you would get hydrogen fusion at
Speaker 1: the core of it, and so you never start to burn,
Speaker 1: because you could just have dust out there and gas
Speaker 1: and just have it. If there's nothing around it, it'll
Speaker 1: just come together as a clump. It will come together
Speaker 1: as a clump. Eventually gravity wins. Right. Gravity is so
Speaker 1: weak but so patient, and it just pulls this stuff
Speaker 1: together whatever you started with. And you know, you might
Speaker 1: wonder like how does that start? And that's a whole
Speaker 1: other fascinating topic. People think that these clouds of gas
Speaker 1: and dust and maybe like a supernova shock wave passes
Speaker 1: through it and that triggers the coalescing. Anyway, we'll talk
Speaker 1: about that in another episode. But whatever you got around
Speaker 1: you forms into a blob and if it's not bright
Speaker 1: enough to burn into a star, then it becomes to
Speaker 1: tonight to start fusion. Right, that's what you yeah, Because
Speaker 1: you know, if you just have a rock out there,
Speaker 1: it's not enough to start fusion. You need enough mass
Speaker 1: that the gravity sort of takes over and you start
Speaker 1: that star and then it's basically a sub brown dwarf star. Man,
Speaker 1: I'm just gonna pass judgment right now, Daniel. I think
Speaker 1: I don't think they should be called stars, alright, Just
Speaker 1: climbing a sub brown dwarves or something. So would you
Speaker 1: call them a rogue planet then? Yeah? Right? Independent? An
Speaker 1: independent planet or yeah, why not? Is there an argument
Speaker 1: against calling them a road planet? Well, some people think that,
Speaker 1: you know, a planet is something that formed around a star,
Speaker 1: and so that a rogue planet. I think the generally
Speaker 1: acceptable term is that a rogue planet something was around
Speaker 1: a star and then got lost. It went rogue. You
Speaker 1: can't you can't be born rogue in astronomy, apparently, I
Speaker 1: see if by planet you mean something that forms around
Speaker 1: a star, then technically I think that doesn't form with
Speaker 1: it around a star is not a planet. But this
Speaker 1: is all semantics, but it's just what people decided to
Speaker 1: call this thing, so they can have words that they
Speaker 1: communicate with and all mean the same thing. Or maybe
Speaker 1: they just like arguing about this stuff at meetings. That's
Speaker 1: probably true also, or maybe if what do you mean
Speaker 1: by star is just like celestial objects, um, then this
Speaker 1: could be sort of a non shining star. Yeah, and
Speaker 1: these things sort of go the same way as the
Speaker 1: rogue planets. That is, when it comes to stars. We
Speaker 1: know more about bigger stars because they burn bright and
Speaker 1: we can see them. It's hard to spot brown dwarfs
Speaker 1: and sub brown dwarfs because they don't shine like stars.
Speaker 1: We think that the number of these things grows very
Speaker 1: quickly though, as you dial down the mass of the
Speaker 1: object from bright star to sub brown dwarf to just
Speaker 1: dark little blob. So there's a lot more sub brown
Speaker 1: dwarfs out there than there are burning stars. There are
Speaker 1: more failed stars and stars. Is that what you're saying?
Speaker 1: Big surprise, right? There are more waiters than celebrities in Hollywood. Wow.
Speaker 1: The analogies just keep keep on rewarding us here. It
Speaker 1: turns out what we've learned here in Los Angeles does
Speaker 1: apply to the rest of the universe. In this one case,
Speaker 1: l A is the center of the universe. Obviously, it
Speaker 1: has taught us something about template is a template for
Speaker 1: the rest of the universe. That is terrifying. That is terrifying, alright, cool,
Speaker 1: So it's pretty interesting to know, to understand, to to
Speaker 1: have a sense that there are giant planets out there
Speaker 1: floating in space without a home. You know, they're just
Speaker 1: cruising through space like a like a spaceship. I guess, yeah,
Speaker 1: And you have to wonder, like, what would it be
Speaker 1: like to stand on the surface of that planet in
Speaker 1: perpetual night. You have no seasons, you right, you could
Speaker 1: do a lot of great astronomy, right because you have
Speaker 1: no sun to interfere with your telescopes. You could have
Speaker 1: a walk around that planet, go all the way around,
Speaker 1: and you would only see the night sky with stars
Speaker 1: in it. Yeah, but you could stay up all night long,
Speaker 1: every night. You would never get a sunburn's right, that industry,
Speaker 1: that industry would just not take off. Good for astronomers,
Speaker 1: bad for practicing gamble. Yeah, and also makers a swimsuits,
Speaker 1: probably because you know it'd be pretty cold. Right. We
Speaker 1: rely on our Sun not just for sunlight but also
Speaker 1: for the warmth, and it provides something like point nine
Speaker 1: seven percent of the energy on the surface of the
Speaker 1: Earth comes directly from the Sun. Really, but aren't there
Speaker 1: planets in our Solar system that are like super hot
Speaker 1: by themselves or is it all also from the Sun?
Speaker 1: There are like Venus is super hot, but all that
Speaker 1: energy comes from the Sun. And the reason it's super
Speaker 1: hot is that has these thick clouds that trap that energy.
Speaker 1: So all the surface energy from all the on all
Speaker 1: the planets in our Solar system is almost all from
Speaker 1: the Sun. But that's from on the surface, if you
Speaker 1: wanted to live on the surface and have a view
Speaker 1: of the night sky. But technically, could you in one
Speaker 1: of these road planets, could you like evolve life inside
Speaker 1: of it where where it is warm? You might because,
Speaker 1: as you say, the core of our planet is warm,
Speaker 1: and that's not from the Sun, that's from the gravitational pressure. Right,
Speaker 1: the Earth is also being squeezed and melt the rock,
Speaker 1: and from the radioactive decays that are happening inside that
Speaker 1: rock that radiates a little bit of energy. And so
Speaker 1: there is you know, there are hot spots underground. And
Speaker 1: so if you're on one of these rogue planets safe
Speaker 1: for example, the Earth went rogue, right, what would happen? Well,
Speaker 1: their ocean good? Not good? Right? You throw away all
Speaker 1: your sunscreen, Sorry about that, and the the oceans would
Speaker 1: freeze and the atmosphere would like turn to snow and
Speaker 1: just like accumulate on the surface of the Earth, which
Speaker 1: would be crazy. But if you go down deep enough,
Speaker 1: they would still be warmth, and so there might be
Speaker 1: enough energy sort of bubbling up through the crust to
Speaker 1: keep like a layer of water melted. Oh. Interesting, you
Speaker 1: could have like underground oceans. Yeah, you could have underground
Speaker 1: oceans that the Earth would be covered in layer of ice,
Speaker 1: but a mile or maybe two miles down there could
Speaker 1: still be water and it might be warm enough to
Speaker 1: sustain life. So you would throw your sunscreen, but not
Speaker 1: your swimsuit. Try to take your swimsuit or maybe your
Speaker 1: wet suit, because I don't think it's going to be
Speaker 1: very warm. But you could find like you know, cracks
Speaker 1: in the Earth's mantle underground where there's geothermal energy, and
Speaker 1: there are there is life the very bottom of the ocean,
Speaker 1: clustered around these thermal vents. Yeah, and they don't have
Speaker 1: any sunlight that you just live off of the hot
Speaker 1: water from these events. They've been planning for this for
Speaker 1: a long time. Yeah, they're ready for They're ready for Earth,
Speaker 1: Bill Rode. They're the rogue life right there, ready to
Speaker 1: take over when Earth goes rogue. There are the waiting
Speaker 1: waiting to rise up. But I think what I what
Speaker 1: I'm saying is that that that could happen in one
Speaker 1: of these rogue planets out there. I mean, there could
Speaker 1: be like a giant floating Jupiter out there in space.
Speaker 1: It's actually like a spaceship full of life under the surface. Yeah,
Speaker 1: and it doesn't have to be that life evolves on
Speaker 1: a planet and then it goes rogue. I think you're saying, like,
Speaker 1: could life evolve on a planet when it's a rogue
Speaker 1: And I think the answer is yeah. You could have
Speaker 1: a good water on a rogue planet and life could evolve,
Speaker 1: and it could evolve under like a mile of ice
Speaker 1: and never see the sky. Right, it might not even
Speaker 1: be aware that the universe is larger than its ocean.
Speaker 1: It would be like rogue life. And you have to wonder, like,
Speaker 1: what kind of technology could you evolve? Like, could you
Speaker 1: become intelligent? Could you evolve technology? Could you drill out
Speaker 1: of the ice and then discover that? Imagine what that
Speaker 1: would be like to be that kind of I want
Speaker 1: to read a science fiction novel about life that evolves
Speaker 1: on a rogue planet and develops the technology, drills as
Speaker 1: of the ice, and then discovers Oh my gosh, the
Speaker 1: university is so much bigger than we ever imagined. What
Speaker 1: a moment. Right, There's a story that you and I
Speaker 1: were talking earlier about. The writer thought Chiang, he has
Speaker 1: a story I don't know if you read it, called
Speaker 1: The Tower of Babel where that's kind of the plot
Speaker 1: where they drill through the ceiling of heaven. Oh my gosh,
Speaker 1: I want to read that story. That sounds awesome. Yeah. Alright,
Speaker 1: So that that's kind of possible, is that there are
Speaker 1: and and there are so many of these road planets
Speaker 1: out there that it's it probably is maybe possible that
Speaker 1: there is life and the life started in one of
Speaker 1: these road planets. Yeah, it's very exciting for the possibility
Speaker 1: of alien life, which you know, I'm a fan of.
Speaker 1: You know, recently we've learned that there are a huge
Speaker 1: number of planets around other stars. That was a big
Speaker 1: moment just in astronomy in general, but also for us
Speaker 1: who promote alien life, to realize that there are other
Speaker 1: places for life in the universe around other stars. That
Speaker 1: was exciting. Now we're learning that that's a tiny fraction
Speaker 1: of all the planets out there, and that there's an
Speaker 1: enormous number of these dark rogue planets, and I think
Speaker 1: it's more challenging for life to form on a rogue planet,
Speaker 1: but hey, you've got more opportunities also, right, there's a
Speaker 1: there's like a hundred billion rogue planets the size of Jupiter. Yeah,
Speaker 1: and maybe tend to a hundred times as many Earth
Speaker 1: sized planets out there, and just in our solar systems,
Speaker 1: I mean just in our galaxy that would be getting
Speaker 1: kind of crowded. Just in our galaxy, I mean, I
Speaker 1: mean the galaxy. There's hundreds and hundreds of billions of
Speaker 1: these and and maybe there are hundreds of billions of galaxies.
Speaker 1: So who knows, right there could be a rogue life
Speaker 1: form out there. My money is that there is. I mean,
Speaker 1: it just seems so much more likely. It seems so
Speaker 1: impossible to imagine that nowhere out there, in any of
Speaker 1: these planets has life begun. There's so many opportunities and
Speaker 1: so many ways for life to happen we haven't even imagined.
Speaker 1: I would definitely put my money on there being rogue
Speaker 1: alien life. Can you imagine them bursting out of their
Speaker 1: shell and be like WHOA what is this? Even crazier though,
Speaker 1: is that like one of these rogue planets could pass
Speaker 1: by our solar system, you know, within a few au
Speaker 1: you know, just outside the edge of Pluto, and we
Speaker 1: wouldn't even see it, and they might not even see us,
Speaker 1: And so we could be like there could be like
Speaker 1: cosmic neighbors and zooming by and we're not even paying attention.
Speaker 1: And maybe, just maybe this happened a few billion years ago,
Speaker 1: and maybe, just maybe an asteroid hit that road planet
Speaker 1: and ejected a piece of rock with life that then landed.
Speaker 1: I'm taking it too far, No, I like that. There
Speaker 1: are a lot It's totally possible. It's possible for life
Speaker 1: to have originated somewhere else and then come to Earth.
Speaker 1: All right, Well, that's pretty interesting to know. It just
Speaker 1: sort of makes you look at space and the night
Speaker 1: sky differently. And in all those places where you only
Speaker 1: see blackness, there could be planets out there, floating and
Speaker 1: possibly with life. Yeah, and this life might not be
Speaker 1: looking back at you. It might be hidden under two
Speaker 1: miles of ice, looking up at the inside of its
Speaker 1: ocean and wondering what l is out there? Right, that's
Speaker 1: no interest in being famous like a star, only because
Speaker 1: they don't even know it's possible. Once they get a
Speaker 1: taste of it. Though, Once stay discovered television, it's all over.
Speaker 1: Who doesn't want to be a star? All right, Well,
Speaker 1: we hope you enjoyed that little tour into the blackness
Speaker 1: of space and what could be out there. Waiting for
Speaker 1: us to discover and as usual, you are in no
Speaker 1: danger as you sit on your couch or sit in
Speaker 1: the seat of your car and listen to us helping
Speaker 1: you explore the universe. All right, We hope you enjoyed that.
Speaker 1: See you next time. Before you still have a question
Speaker 1: after listening to all these explanations, please drop us a line.
Speaker 1: We'd love to hear from you. You can find us
Speaker 1: on Facebook, Twitter, and Instagram at Daniel and Jorge That's
Speaker 1: one word, or email us at Feedback at Daniel and
Speaker 1: Jorge dot com. Thanks for listening and remember that Daniel
Speaker 1: and Jorge, Hey, Explain the Universe is a production of
Speaker 1: I Heart Radio. From more podcast from my Heart Radio
Speaker 1: visit the i heart Radio app, Apple Podcasts, or wherever
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