Speaker 1: Hey, Daniel, do you ever worry about the ethics of
Speaker 1: using a telescope?
Speaker 2: What do you mean? What are the ethical questions about
Speaker 2: looking through a telescope?
Speaker 1: I mean, like what they're looking at?
Speaker 2: Well, I'm not pointing them at my neighbor, if that's what.
Speaker 1: You mean, not your next door neighbor. What about your
Speaker 1: next galaxy neighbor.
Speaker 2: Are you asking if we have the right to look
Speaker 2: at distant objects in the sky?
Speaker 1: Yeah, you know, like what if there are aliens there
Speaker 1: on a planet or a moon and we're like spying
Speaker 1: on them?
Speaker 2: Well, I hope they're not offended if we catch them
Speaker 2: sunbathing or I guess starbathing.
Speaker 1: Aren't all stars suns? But yeah, don't you think aliens
Speaker 1: have a right to privacy?
Speaker 2: I don't know. Maybe they're alien celebrities, so they're like
Speaker 2: starbathing stars.
Speaker 1: Wait, are you saying celebrities can have privacy either? Are
Speaker 1: you secretly a starker?
Speaker 2: No, I'm saying astronomers are just interstellar paparazzi.
Speaker 1: Well, oh, it sounds like they need to draw their
Speaker 1: curtains more. Why just have you don't get the rest
Speaker 1: of us punch in the face, Hi am horhem a
Speaker 1: cartoonist and the author of Oliver's Great Big Universe.
Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor
Speaker 2: at u C Irvine. And if it gets the aliens
Speaker 2: to come, I want them to punch us in the face.
Speaker 1: Us in the face. How about just you in the face?
Speaker 1: I mean, please, don't volunteer my face for your science.
Speaker 2: Us volunteering humanity's collective face.
Speaker 1: Some of us are sensitive in the face.
Speaker 2: It might be worth a puncher too, to learn that
Speaker 2: we're not alone in the universe.
Speaker 1: Can we pick where they're going to punch us, you know,
Speaker 1: like when you're playing as kids.
Speaker 2: You mean in the Daniel part of the face, rather
Speaker 2: than the joey part of the face.
Speaker 1: Definitely the Daniel part. But anyways, Welcome to our podcast,
Speaker 1: Daniel and Jorge Explain the Universe, a production of iHeartRadio.
Speaker 2: In which we try to teach you all about the
Speaker 2: mysteries of the universe, rather than punching you in the
Speaker 2: face with them. We think that it's possible to gently
Speaker 2: absorb all of the crazy intricacies of how the universe works,
Speaker 2: from its tiny little particles to its mysterious swirling black holes.
Speaker 2: Without getting bruised, basically anywhere on your body. We seek
Speaker 2: to serve up the mysteries of the universe in a
Speaker 2: gentle and comfortable manner.
Speaker 1: That's right. We bring you the one two punch of
Speaker 1: science and bad dad jokes to talk about all the
Speaker 1: amazing things that are happening in the universe, all the
Speaker 1: peaceful things and also all of the combatitive things, and.
Speaker 2: The mysteries that we love to dig into. Are the
Speaker 2: ones that tell us about our context in the universe.
Speaker 2: Is where we are in the universe weird and unusual?
Speaker 2: Or are there many such backyards with many such podcasts
Speaker 2: giving all the same dad jokes?
Speaker 1: Yeah, that has been one of the biggest questions in
Speaker 1: the universe is are we alone in the universe? Or
Speaker 1: are we one of many many alien civilization out there
Speaker 1: in space? And are we the only ones making dad jokes?
Speaker 2: And how many of them are spying on us while
Speaker 2: we're sunbathing in our backyards.
Speaker 1: Well, I guess you know, technically, in an infinite universe
Speaker 1: that there's probably a planet out there where dad jokes
Speaker 1: are like the epitome of intelligence and literature.
Speaker 2: Are you saying that's not our universe? Are you saying
Speaker 2: that's not our planet.
Speaker 1: That is definitely not. I think there's a reason they're
Speaker 1: called dad jokes, not just jokes. But maybe there's an
Speaker 1: alien species out there where you know, it's like the
Speaker 1: height of width, you know.
Speaker 2: Right, Well, we should try to sell our books on
Speaker 2: that planet then, because we have a lot of readers.
Speaker 1: Yeah, would be intergalactic bestsellers, not just international bestsellers.
Speaker 2: But we're not just interested in whether our books will
Speaker 2: sell to alien species. We're interested in whether there are
Speaker 2: aliens out there, whether life exists in other parts of
Speaker 2: the galaxy. And part of that question is asking whether
Speaker 2: our whole setup is unusual. Are there stars with planets
Speaker 2: around them? Do those planets have similar conditions to the
Speaker 2: planets here? Is there something weird and strange about the
Speaker 2: Solar System? Or is it very common?
Speaker 1: Yeah? Is the planet Earth a rare gem that exists
Speaker 1: out there in the cosmos or is it sort of
Speaker 1: like a you know, cheap chot sky that you can
Speaker 1: find anywhere.
Speaker 2: In just a few decades ago, we didn't know the
Speaker 2: answers to basic questions like are there planets around other stars? Fortunately,
Speaker 2: as we develop new and more powerful eyeballs, We've been
Speaker 2: able to discover those planets, and now we are pushing further.
Speaker 2: We are asking deeper and more subtle questions about the
Speaker 2: nature of those planets, their atmospheres, their surfaces, even what's
Speaker 2: in orbit around them.
Speaker 1: So today on the podcast, we'll be tackling the question
Speaker 1: could we see moons around exo planets? Now, Daniel, I
Speaker 1: imagine these are like moons, like the orbiting celestial bodies,
Speaker 1: and not like aliens mooning.
Speaker 2: Or maybe alien death stars. Right, we don't care. We
Speaker 2: just wanted to discover them.
Speaker 1: Wait wait, wait, wait, I think we maybe should. If
Speaker 1: there are alien death stars, maybe we don't want to
Speaker 1: meet them. Maybe these are not the aliens we're looking for.
Speaker 2: I think we'd rather know they're there than live in ignorance,
Speaker 2: wouldn't we.
Speaker 1: If we know they're there, then they know we're here.
Speaker 2: We could just use that Jedi mind trick, that's.
Speaker 1: Right, make them forget and dazzle them with our dad
Speaker 1: jokes and then it'll be like what what And then
Speaker 1: they won't want to associate with us, and then problem solve.
Speaker 2: These aren't the jokes you're looking for.
Speaker 1: That's right, or they'll want to annihilate us right away, But.
Speaker 2: We are curious about the environments of these planets. Having
Speaker 2: moons affects life on Earth and tells us a lot
Speaker 2: about the history of that solar system, and just in general,
Speaker 2: we want to know, like our solar system is pretty mooney,
Speaker 2: are other solar systems mooney as well?
Speaker 1: Mooney and wonderful? Because I think, as you said earlier,
Speaker 1: up until a little bit a few years ago, a
Speaker 1: few decades ago, we didn't even have confirmation there were
Speaker 1: other planets out there, right, We just imagined or assume
Speaker 1: there were, but we had not actually seen any.
Speaker 2: Yeah, it could have been that we were one of
Speaker 2: very very few, perhaps singular solar systems that had planets
Speaker 2: around it. It could have been that the reason that there's
Speaker 2: life here around our Sun is that it was the
Speaker 2: only one with a rocky habitable perch. Now, of course,
Speaker 2: we know the opposite is true. We know there are
Speaker 2: planets all over the galaxy. We've seen a few thousand
Speaker 2: of them, and we estimate that there are zillions of them,
Speaker 2: that they're almost literally everywhere in the galaxy. That's a
Speaker 2: real change in the way we see our whole context
Speaker 2: in the universe.
Speaker 1: Yeah, because imagine even like jumping from our sun to
Speaker 1: the stars in the sky was kind of a big
Speaker 1: leap for humanity too, right, Like, we can look at
Speaker 1: our sun and it looks circular, at least if you
Speaker 1: see a projector of it or through a filter, you
Speaker 1: can see that it's a giant ball. But the stars
Speaker 1: in the sky just look like little pinpoints, And so
Speaker 1: it must have been a pretty big leap to think,
Speaker 1: you know, those pinpoints are actually stars.
Speaker 2: It is a pretty big leap. And to understand how
Speaker 2: big a leap it is to understand how far away
Speaker 2: they are is pretty tricky. I mean, even the Greeks
Speaker 2: knew that the other stars were likely suns, but they
Speaker 2: thought they were much much closer than they actually are.
Speaker 2: The Greeks couldn't understand how far away these stars actually were.
Speaker 2: So yeah, it really expands your whole mental picture of
Speaker 2: the universe to understand that our sun is one of
Speaker 2: many of those stars, and that therefore there are lots
Speaker 2: and lots of places where life might exist in the universe.
Speaker 1: Yeah, and those stars out there are really far away,
Speaker 1: that's why they look like pinpoints. And so basically, until recently,
Speaker 1: it was almost impossible to really see a planet on them, right.
Speaker 2: It was very tricky, and for a long time people
Speaker 2: thought it might be impossible. But astronomers are very clever
Speaker 2: and very hard working, and now we have lots of
Speaker 2: tricks to discover planets around other stars, and so now
Speaker 2: people are pushing into what many people believe is impossible,
Speaker 2: understanding the atmospheres, the surfaces, and maybe even the orbiting
Speaker 2: bodies of those planets.
Speaker 1: I wonder what did I'm sure we'll get into it,
Speaker 1: But what's the driving question here to know whether an
Speaker 1: exoplanet has a moon? Like do you think maybe the
Speaker 1: moon is the one that's habitable, or you're just trying
Speaker 1: to study other moons?
Speaker 2: I think all of those things. Moons might be the
Speaker 2: most commonplace for life in the universe. It might be
Speaker 2: that moons around big planets are the best place for
Speaker 2: life to evolve, and the humanity is very, very weird
Speaker 2: for developing directly on the surface of a planet. On
Speaker 2: the other hand, moons also tell you a lot about
Speaker 2: the history of the Solar System, how it formed, how
Speaker 2: it came to be, which tells you a lot about
Speaker 2: where you expect to find planets that might have life
Speaker 2: on them. So it's as much about understanding the detailed
Speaker 2: history of other solar systems and thinking about where we
Speaker 2: might find life well as usually.
Speaker 1: We were wondering how many of you out there had
Speaker 1: thought about this question and wondered if we could see
Speaker 1: moons in other planets.
Speaker 2: Thanks very much to everybody who offers their unprepared insights.
Speaker 2: We really enjoy this segment of the podcast and we
Speaker 2: want to hear from you. Please don't be shy write
Speaker 2: to us to questions at Danielandjorge dot com.
Speaker 1: So think about it for a second. Do you think
Speaker 1: we could ever see moons around exoplanets? Here's what people
Speaker 1: have to say.
Speaker 3: Just finished listening to the podcast with the exoplanet researcher
Speaker 3: and do I think we could see them? No, but
Speaker 3: we do have confirmed existence of moons around exoplanets. I
Speaker 3: believe that number is currently at two.
Speaker 4: I think we will definitely be able to see moods
Speaker 4: throughout exoplanets. James Web will be able to analyze the
Speaker 4: atmospheres of exoplanets and it might even be strong enough
Speaker 4: to see moons. And if not, James Web, there's probably
Speaker 4: going to be another set of eyeballs in the future
Speaker 4: that we'll be able to do it.
Speaker 5: I think that in order to be able to detect
Speaker 5: moons of exoplanets, we would need very sensitive telescope and
Speaker 5: other instruments capable of measuring the lightest, faintest of changes
Speaker 5: in the light emitted from other stars.
Speaker 6: Yes, in terms of finding excello planet moons to be
Speaker 6: to measure the gravity between that planet, that exoplanet a
Speaker 6: star and see if we can account for any extra
Speaker 6: gravity that would be from the moon or maybe some
Speaker 6: sort of nudger or tug on that moon.
Speaker 7: I think this depends on your definition of what it
Speaker 7: means to see a moon. It seems like it would
Speaker 7: be nearly impossible to imagine directly imaging any especially given
Speaker 7: that we haven't directly imaged and exo planet yet. But
Speaker 7: if we had a specially large planet around a star
Speaker 7: with a big enough percentage of its star's mass, and
Speaker 7: if it in turn had a moon that was a
Speaker 7: significant percentage of its mass, then I would imagine that
Speaker 7: they could probably detect the combined wobble of the interaction
Speaker 7: between those three.
Speaker 1: All Right, a lot of optimism here. I feel everyone's like, sure, yeah, eventually,
Speaker 1: sort of in one way or another, Yeah.
Speaker 2: There's this bubbling sense that eventually we could figure out
Speaker 2: basically any problem that in our future lies more and
Speaker 2: more powerful techniques and telescopes and smarter people that could
Speaker 2: extract this kind of information from the universe. I love
Speaker 2: that it's so inspiring to hear people's optimism. Yeah.
Speaker 1: Yeah, And I think by smarter people you mean the engineers, right.
Speaker 2: I mean my students and my students'.
Speaker 1: Students and the engineers that actually do it for them, right.
Speaker 1: I think that's what you're saying.
Speaker 2: Right, I know, we just submit the work order and
Speaker 2: it comes back. You know who knows who does YadA,
Speaker 2: YadA YadA. You gotta telescope.
Speaker 1: That's right, We toy anonymously. That's what happens to all
Speaker 1: smarter people.
Speaker 2: No, of course, the field of astronomer is filled with
Speaker 2: people who analyze the data, and people who build the devices,
Speaker 2: and people who plan for the next generation of devices.
Speaker 2: It's a whole ecosystem of smart people, from physicists to
Speaker 2: planetary scientists, to engineers to computer scientists, all sorts of
Speaker 2: people all working together.
Speaker 1: Well, this is a pretty big question, or I guess
Speaker 1: a small question is how do you see the moon
Speaker 1: around a planet orbiting a star that is light years
Speaker 1: or at least millions of miles away. It's a pretty
Speaker 1: tough question.
Speaker 2: It is a pretty tough question, and it's going to
Speaker 2: require us to get even better at seeing those planets.
Speaker 2: All the techniques we have for seeing moons are basically
Speaker 2: like super powerful versions of the ways that we see planets.
Speaker 1: All right, well, let's break it down for people, Daniel.
Speaker 1: First of all, what is an exoplanet and what do
Speaker 1: we know about them?
Speaker 2: So an exoplanet is very simply just a planet around
Speaker 2: another star. Planets are the planets around our sun. An
Speaker 2: exoplanet is a planet around for example, Alpha Centauri or
Speaker 2: any other star that's not our Sun XO. Just meaning
Speaker 2: like outside the Solar system.
Speaker 1: M I see like an outer planet? Where I guess not,
Speaker 1: because an outer planet could be the planets in our
Speaker 1: Solar system. Like anything outside of our Solar system that's
Speaker 1: a planet is an exoplanet.
Speaker 2: Yeah, a planet around another star would be an exoplanet.
Speaker 2: And they have to be far away because the nearest
Speaker 2: star is several light years away, which is really really far.
Speaker 2: It's very far compared to the distance between the planets,
Speaker 2: and so an exoplanet is going to be very, very
Speaker 2: different from any planet in our Solar system, just in
Speaker 2: terms of like where it is.
Speaker 1: And we hadn't actually seen one or confirmed there were
Speaker 1: any planets around any other stars until basically like thirty
Speaker 1: years ago.
Speaker 2: Right, Yeah, it's incredible if you make a plot of
Speaker 2: like the number of planets we've seen over time, dating
Speaker 2: back like thousands of years until fairly recently, we'd only
Speaker 2: ever seen like six, right, and then Urinus and Neptune
Speaker 2: are discovered in the last few hundred years, and then
Speaker 2: Pluto and then un Pluto, so we're back down to eight.
Speaker 2: And then it wasn't until the nineteen nineties, only thirty
Speaker 2: years ago, that we finally saw one outside of our
Speaker 2: Solar system. Until then, we only speculated, we only imagined,
Speaker 2: we'd had calculations, we had speculations, but we had no
Speaker 2: actual data until about thirty years ago when we developed
Speaker 2: these techniques to see the planets or to deduce their
Speaker 2: existence around other stars.
Speaker 1: Yeah, because, as one of the listeners who replied earlier said,
Speaker 1: the word see is a little bit tricky, right, We
Speaker 1: didn't actually see planets in other stars. We sort of
Speaker 1: like figure out they were there, but we didn't actually
Speaker 1: see them.
Speaker 2: Yeah, exactly, and so we have these really cool techniques
Speaker 2: to deduce that they exist, and you know, you can
Speaker 2: argue philosophically about what does it mean to see something,
Speaker 2: But we didn't see exoplanets directly until much more recently.
Speaker 2: The first discoveries came from just observing the impact of
Speaker 2: those planets on the stars, which of course we can.
Speaker 1: See, which is kind of crazy to think, right, because
Speaker 1: what possible impact and the Earth have on the Sun.
Speaker 1: The Sun is like a million times heavier than the Earth,
Speaker 1: right or more.
Speaker 2: It's all about making these things more sensitive and getting
Speaker 2: down to the details. Like mostly you're right, the Earth
Speaker 2: has basically no impact on the Sun. But if you
Speaker 2: analyze the Sun super duper closely, then yeah, the Earth
Speaker 2: does have a little bit of an impact on the Sun,
Speaker 2: the same way that, for example, the other planets have
Speaker 2: an impact on the Earth. Mostly, the Earth's orbit around
Speaker 2: the Sun is just a story of two bodies, the
Speaker 2: Earth and the Sun, orbiting their combined center of mass.
Speaker 2: But if you get super dup or precise about it,
Speaker 2: then you have to take into account, like the effect
Speaker 2: of Jupiter and Saturn on the orbit of the Earth.
Speaker 2: So all of these little complications can actually reveal the
Speaker 2: rich structure of the Solar system if you study them
Speaker 2: with enough precision.
Speaker 1: It's pretty mind body to think. I mean, the Sun
Speaker 1: is so big and it's the Earth is just this
Speaker 1: tiny little marble next to it, like that it would
Speaker 1: have an effect on the whole thing. Like I can
Speaker 1: see maybe pulling a little bit more on the part
Speaker 1: of the Sun that's closest to the Earth, maybe some
Speaker 1: of that cosma, But to think that it could move
Speaker 1: the entire Sun is pretty hard to believe.
Speaker 2: Yeah, Well, imagine instead you had two objects that had
Speaker 2: the same mass, right, like two stars the same mass,
Speaker 2: and they're orbiting each other. Clearly they have an effect
Speaker 2: on each other. What they're orbiting is actually a point
Speaker 2: right in between them. Now, as you shrink one of
Speaker 2: those things down and grow the other one so it
Speaker 2: becomes asymmetric, the points they're orbiting moves towards the center
Speaker 2: of the heavier one. If one of them was infinitely
Speaker 2: massive or the other one was massless, then they would
Speaker 2: both be orbiting a point at the center of the
Speaker 2: biggest object. But if the Earth is not massless, if
Speaker 2: it actually does have some mass, then it's pulling that
Speaker 2: center of mass a little bit away from the center
Speaker 2: of the Sun. And if you measure the motion of
Speaker 2: the Sun very precisely, you can detect that. And that's
Speaker 2: why these things are so hard. That's why it took
Speaker 2: so long to see these things, is that it requires
Speaker 2: really precise measurements now of the motion of stars in
Speaker 2: other solar systems.
Speaker 1: Yeah, it's pretty mind blowing. But I guess maybe one
Speaker 1: thing that helped was that we didn't start looking for
Speaker 1: Earth sized planets, right, we start looking for Jupiter sized planets.
Speaker 2: Well, we started looking for anything we could see, and
Speaker 2: we didn't know what was out there, right. We had
Speaker 2: speculation about what kind of planets might exist in other
Speaker 2: solar systems, but we didn't really know what we could find.
Speaker 2: You're right though, that the first techniques we developed were
Speaker 2: more powerful for Jupiter sized planets. The bigger the planet
Speaker 2: and the closer it was to the star, the easier
Speaker 2: it was for us to find them.
Speaker 1: Like, those were the first planets found right where. They
Speaker 1: were basically giant gas planets.
Speaker 2: Yeah, they call them hot Jupiters because they're the size
Speaker 2: of Jupiter and they're very close to the star. The
Speaker 2: closer they are the star, the faster the orbit, the
Speaker 2: easier it is to find them because they tug on
Speaker 2: the star. And so one of these techniques is called
Speaker 2: the radial velocity method. You look at the light from
Speaker 2: the star and you see if it's shifted in frequency.
Speaker 2: If a star is moving away from you, it's red shifted.
Speaker 2: If a star's moving towards you, it's blue shifted. If
Speaker 2: a star is getting wiggled by a planet that's orbiting it,
Speaker 2: then it's going to get red shifted and blue shifted,
Speaker 2: red shitted and blue shifted. It's going to wiggle a
Speaker 2: little bit in its frequencies. And that's what they look for.
Speaker 2: But that's more powerful for big planets and planets that
Speaker 2: are close to their stars.
Speaker 1: But then we develop other ways to look at planets,
Speaker 1: right really quick, What are some of these other ways
Speaker 1: that we can see exoplanets.
Speaker 2: So another way is the transit method, which is basically
Speaker 2: an eclipse. As the planet passes in front of the star,
Speaker 2: it dims it a little bit, it blocks some of
Speaker 2: the light. And so again if you're just measuring the
Speaker 2: light from the star roughly, you're never going to notice this.
Speaker 2: If you make very precise measurements of the light from
Speaker 2: the star, you can see these dips and you can
Speaker 2: see the patterns. If the planet goes around many many times,
Speaker 2: you'll see the same pattern over and over again. Unfortunately,
Speaker 2: this one is also best at seeing big planets that
Speaker 2: eclipse the light more and close by planets that block
Speaker 2: more light from their sun and go around many times,
Speaker 2: so we can see many transits.
Speaker 1: Yeah, like if the Moon didn't reflect any light and
Speaker 1: you can see it in the night sky, you could
Speaker 1: still maybe every once in a while know it's there
Speaker 1: because it would block the light from the Sun. You
Speaker 1: would see an eclipse exactly.
Speaker 2: And there are techniques that will let you see planets
Speaker 2: that are further from the Sun, and these are actually
Speaker 2: the direct imaging ones. We can look at a solar
Speaker 2: system and we can block the light from the sun
Speaker 2: called the corona graph, a little thing that prevents the
Speaker 2: light from the star from getting into the telescope and
Speaker 2: only look at the stuff around it. And now we
Speaker 2: have powerful enough telescopes that you can actually see dots
Speaker 2: around those stars. So these are direct images of light
Speaker 2: from those planets, and those are most powerful at seeing
Speaker 2: planets that are far away from the star. There's the
Speaker 2: further they are from the star, the easier it is
Speaker 2: to tell them apart from the blinding light from the
Speaker 2: star itself.
Speaker 1: Yeah, it's like you basically put your thumb, like if
Speaker 1: you look up at the skuy you put your thumb
Speaker 1: over the star and then you see there are any
Speaker 1: other twinkles around it, right.
Speaker 2: Exactly, And so we have like a few pixels of
Speaker 2: light from these planets. Of course, the planets themselves are
Speaker 2: not glowing. It's all reflected light from their star. But
Speaker 2: you know, it bounced off the planet first, so it's
Speaker 2: just like looking at the planet the same way the
Speaker 2: Earth is illuminated by our sun.
Speaker 1: That's the closest we have of an actual picture of
Speaker 1: another planet, right, Like, I've seen the plots. They're a
Speaker 1: bit old right now. We've had these photos for fish
Speaker 1: seen hears or something like that.
Speaker 2: Yeah, they're getting better and better, but they're not great.
Speaker 2: I mean they're pretty fuzzy. If you took pictures of
Speaker 2: your kids like this, none of your relatives would be
Speaker 2: very impressed with your photography. It's like a few pixels
Speaker 2: here and there.
Speaker 1: Yeah, although my kids nowadays avoid getting their picture taken
Speaker 1: as I think most kids do, and so they're kind
Speaker 1: of a big blur anyways, And then what's the last
Speaker 1: kind of method we used to detect these exoplanets.
Speaker 2: The last technique is called micro lensing, and that's essentially
Speaker 2: using the planet as a lens to distort light from
Speaker 2: some other star. If there's light from another star behind
Speaker 2: the Solar system that's passing through that Solar system, then
Speaker 2: it can get bent around the planet. Because the planet,
Speaker 2: of course is massive and it changes the shape of
Speaker 2: space and so it can act like a giant lens.
Speaker 2: This is sort of similar to the way we can
Speaker 2: see dark matter in the sky by seeing its gravitational lensing.
Speaker 2: So here's called micro lensing because there's so smaller amount
Speaker 2: of lensing as the light passes around the planet.
Speaker 1: Yeah, you're seeing how the bends the light coming at you.
Speaker 1: And so those are the different ways that we can
Speaker 1: see exoplanets. But now the big question is are there
Speaker 1: moons around these exoplanets out there in the universe? What
Speaker 1: is it like on those moons, could we ever see them?
Speaker 1: And how are we going to see them? So let's
Speaker 1: dig into that. But first let's take a quick break.
Speaker 1: All right, we're talking about finding exo moons, So you
Speaker 1: call them exo moons if it's a moon around an exoplanet.
Speaker 2: Yeah, we call them exo moons unless you have a
Speaker 2: better name for.
Speaker 1: Them, turning to be like exoxo moons because it's like
Speaker 1: a different body out on an exoplanet.
Speaker 2: There are exo moons around exo planets. There are two
Speaker 2: exos there. But I think exo just means in another
Speaker 2: solar system.
Speaker 1: So well, what do you call the moons around Jupiter?
Speaker 2: Moons?
Speaker 1: Moons?
Speaker 2: Yeah, there you go, and no moons now, just moons.
Speaker 2: And you know, Jupiter is a great example because something
Speaker 2: we noticed and our solar system is there are kind
Speaker 2: of a lot of moons, right, we have two hundred
Speaker 2: and twenty six moons in our solar system. And something
Speaker 2: we wonder is like, is that weird? Are we kind
Speaker 2: of moony? Or are we moon poor compared to other
Speaker 2: solar systems? Like what's a typical number of moons to have?
Speaker 2: We just don't even know.
Speaker 1: And we have a whole episode about how like moons form, right,
Speaker 1: how you get a moon?
Speaker 2: Yeah, exactly. It's really fascinating the number of ways that
Speaker 2: you can get a moon, they can form with a planet,
Speaker 2: you can capture them, it can be the result of
Speaker 2: a collision. The point is that it tells you a
Speaker 2: lot about the history of the Solar System. It's like
Speaker 2: a record of what happened here before you showed up.
Speaker 1: Right, Like our Solar System we've talked about before, it
Speaker 1: was a pretty chaotic place, and so it kind of
Speaker 1: makes sense that there was just a lot of debris
Speaker 1: out there floating, flying around, and so not all of
Speaker 1: it was going to get into planets, and so it
Speaker 1: makes sense we have a smaller box that they're orbiting
Speaker 1: the bigger bodies.
Speaker 2: Yeah, although we have an incredible range of sort of
Speaker 2: size of those bodies. Like our moon is huge. It's
Speaker 2: like more than one percent the mass of the Earth,
Speaker 2: which is very very unusual. More typical size is like
Speaker 2: one ten thousands the mass of the planet. But then
Speaker 2: there's also like Sharon, which is one eighth the mass
Speaker 2: of Pluto, even though Pluto not officially a planet anymore.
Speaker 2: But we have this incredible variation in the sizes of
Speaker 2: the moons and in their origin and their composition. It's
Speaker 2: really an incredible diversity.
Speaker 1: Or I guess in the relative size, right, because some
Speaker 1: of the moons around Jupiter, aren't they almost the same
Speaker 1: size as our moon?
Speaker 2: Yeah? Exactly, we're talking about the relative sizes, and some
Speaker 2: of the moons around Jupiter are huge, absolutely, and potential
Speaker 2: places for life to exist, which is one of the
Speaker 2: things that makes us wonder whether Moon's around exoplanets might
Speaker 2: also be habitable.
Speaker 1: All right, Well, we talked about how we can see
Speaker 1: other planets in other stars in the universe, and I
Speaker 1: guess as as star wars were like, Okay, we've seen those.
Speaker 1: Now let's increase the difficulty. Exactly, fine, things orbiting not
Speaker 1: just around other stars, but around the things that are
Speaker 1: orbiting around other stars.
Speaker 2: And this is the game in science, right. People have
Speaker 2: come along and done the simplest thing. All right, now,
Speaker 2: let's come along and do the next harder thing. And
Speaker 2: then the next generation's like, well that was easy. Now
Speaker 2: let's do the next harder thing. And so I love
Speaker 2: how we're always making the progress. We're always pushing the
Speaker 2: boundaries here.
Speaker 1: But are we done though? I feel like I'm still
Speaker 1: waiting for that, you know, actual picture of another planet
Speaker 1: in another solar system, you know, like a like a photograph, photograph.
Speaker 2: Yeah, No, we're never done right. We're always pushing, but
Speaker 2: we're pushing in lots of directions. Simultaneously, people are working
Speaker 2: on that photograph. One idea that's being worked, one which
Speaker 2: we talked about in the podcast, is like using the
Speaker 2: Sun itself as a gravitational lens. You put a camera
Speaker 2: out deep in the solar system. You can use the
Speaker 2: Sun to gather a huge amount of light from a
Speaker 2: distant solar system, and the Sun will focus all that
Speaker 2: light on the camera you have out like near Neptune,
Speaker 2: treating the Sun like this huge lens and making a
Speaker 2: solar system sized camera that could give you a picture
Speaker 2: of the surface of exoplanets.
Speaker 1: Wait what like our sun?
Speaker 2: Yeah, our sun. You have the Sun acting like a
Speaker 2: gravitational lens, gathering light and then focusing it on a
Speaker 2: camera you put like way deep in the soil system,
Speaker 2: and you can take a picture of something super far
Speaker 2: away with a lens effectively the size of the Sun.
Speaker 1: Whoa pretty cool, let's do it, Picker, It didn't happen.
Speaker 2: It's pretty tricky project because you have to get a
Speaker 2: camera like pretty far out in the solar system and
Speaker 2: that could take decades, and then moving it takes a
Speaker 2: long time, but it definitely can be done, and someday
Speaker 2: we will see the surface of exoplanets.
Speaker 1: And then you got to get the aliens to stay
Speaker 1: still and smile for the camera, and it takes, you know,
Speaker 1: a thousand years just to say cheese.
Speaker 2: Yeah. Then they have to sign that waiver, you know,
Speaker 2: so you can publish the picture.
Speaker 1: There you go. You seem really concerned about the aliens here.
Speaker 2: Hey man, I'm just looking after them. I just don't
Speaker 2: want them to come and punch us in the face
Speaker 2: over something silly like legal forms.
Speaker 1: You don't want to punch you in the phase when
Speaker 1: you take a picture of them in the bathroom, I.
Speaker 2: Have no idea when they're in the bathroom, Like, what
Speaker 2: are you doing over there? Is that what you call
Speaker 2: the bathroom? I don't know. I'm just taking pictures.
Speaker 1: I see ignorance.
Speaker 2: Yeah, look, look, I just want to say, there's a
Speaker 2: lot of moon jokes I'm not.
Speaker 1: Making around here, thankfully, thankfully. All right, Well, then how
Speaker 1: can we see these ex moons? We basically use the
Speaker 1: same methods we used to detect other planets, or are
Speaker 1: we trying some different things?
Speaker 2: Both The bread and butter is to take the same
Speaker 2: methods and make them super duper sensitive. Like the transit
Speaker 2: method is one of the most sensitive methods for finding
Speaker 2: these planets if everything is lined up, and you can
Speaker 2: also use it to discover the Moon's in a couple
Speaker 2: of ways, because the moon will affect how the planet
Speaker 2: blots out the light from the star Number one, it
Speaker 2: can affect when it happens like the moon is tugging
Speaker 2: on the planet the same way the planet is tugging
Speaker 2: on the star, which makes when the planet gets in
Speaker 2: front of the Sun and blocks its light change a
Speaker 2: little bit. As the moon is orbiting the planet, it's
Speaker 2: like yanking on the planet a little bit, So it
Speaker 2: changes the timing in these transits, right.
Speaker 1: Like I guess, like our moon, the moon here is
Speaker 1: making the Earth wiggle a little bit. And so the
Speaker 1: idea is that in another planet, in another solar system,
Speaker 1: if it has a moon, a big enough moon, it's
Speaker 1: making that planet wiggle, and so when it moves in
Speaker 1: front of its star, it's going to block the light
Speaker 1: in a wiggly fashion exactly.
Speaker 2: And if you count enough of these transits, you can
Speaker 2: start to notice these patterns, and then you can fit
Speaker 2: it to a model you can say, like, well, can
Speaker 2: I explain why this transit was a little bit later
Speaker 2: and that transit was a little bit earlier. By assuming
Speaker 2: that there's a moon there pulling on it, is it
Speaker 2: all consistent? You don't just like look for noise and say, well,
Speaker 2: I don't know it was noisy, maybe there was a moon.
Speaker 2: You have a specific description of what that moon might
Speaker 2: look like and how it would affect the planet.
Speaker 1: Right, Like, if you notice it the wiggling is regular,
Speaker 1: then you know there's something going on, Like it can't
Speaker 1: just be like random wiggling exactly.
Speaker 2: And there's a second way, which is that the moon
Speaker 2: itself can also contribute to blocking the light, not just
Speaker 2: when the planet blocks it, but the moon could also
Speaker 2: have its own little moony eclipse, right because if the
Speaker 2: moon is lined up at the same time as the planet,
Speaker 2: it can add a little bit of eclipsiness to the planet.
Speaker 2: It effectively makes the planet's shadow a little bit bigger.
Speaker 2: And if you have a model for how that moon
Speaker 2: is orbiting the planet and when the planet is going
Speaker 2: around the Sun, you can predict exactly when the Moon's
Speaker 2: going to be in the right position to add to
Speaker 2: the eclipse.
Speaker 1: But wouldn't it always block the lights in the sun, Like,
Speaker 1: you know, it's pretty small compared to that planet, and
Speaker 1: the planet is small compared to the Sun. Wouldn't it
Speaker 1: always be sort of insight or in view.
Speaker 2: It might always be in view, but it doesn't always
Speaker 2: have to contribute to the amount of eclipse. Like let's
Speaker 2: say they're all lined up. If you see like moon
Speaker 2: and then planet, then star. If the moon is already
Speaker 2: in the shadow of the planet, then it's not contributing
Speaker 2: to the decrease in the light. Only when the Moon
Speaker 2: is sort of offset a little bit from the planet,
Speaker 2: so it like adds a little shoulder to the planet.
Speaker 2: Is it going to increase the amount of light that's
Speaker 2: being blocked? And that's the kind of thing they look for.
Speaker 2: They look for these trans dips with like a little
Speaker 2: wiggle on the down edge or a wiggle on the
Speaker 2: up edge when the moon is peaking around the side
Speaker 2: of the planet. Basically have to have moon rise or
Speaker 2: moon set along the planet for it to contribute to
Speaker 2: the transit dip.
Speaker 1: Wow, but now we're talking about like a super duper
Speaker 1: tiny dip in the light, right Like our moon would
Speaker 1: block very little of our giant Sun.
Speaker 2: Yeah, exactly. We're talking about really sensitive measurements, and until
Speaker 2: recently people allowt this is impossible. You know, you'd need
Speaker 2: very very accurate understanding of the light and very precise
Speaker 2: measurements of the intensity of the light coming from these things.
Speaker 2: So it wasn't until like two thousand and seven, more
Speaker 2: than a decade after exoplanet discoveries, the people really started
Speaker 2: working on this in detail, like taking the idea seriously.
Speaker 2: And one of the biggest challenges is that most of
Speaker 2: these techniques that we've used to find exoplanets are good
Speaker 2: at finding planets close to the star, like we talked
Speaker 2: about hot Jupiter's right, really big planets really close to
Speaker 2: their stars. But those planets are unlikely to have moons.
Speaker 2: And though that makes it very challenging to find any
Speaker 2: of these moons.
Speaker 1: Why are they unlikely to have moons?
Speaker 2: For the same reason that Mercury and Venus don't have
Speaker 2: moons in our Solar system, right, all the other planets
Speaker 2: have them, and Mercury and Venus don't. It's because of
Speaker 2: the tidal forces from the Sun. As you get close
Speaker 2: to the Sun, the tidal forces, the difference in gravity
Speaker 2: from one side to the other side of a planet,
Speaker 2: for example, get very very intense, and that will just
Speaker 2: disrupt the orbit of a moon. In order to have
Speaker 2: a moon orbiting a planet, you basically need the Sun
Speaker 2: to leave it a little bit alone. You need a
Speaker 2: planet to be able to dominate the gravitational experience of
Speaker 2: that moon, so the moon can be trapped in an orbit.
Speaker 2: But if the Sun is really really close by, then
Speaker 2: the Sun's tidal forces make a moon's orbit impossible.
Speaker 1: Like they'll tend to pull the Moon towards the Sun
Speaker 1: and then eventually that moon will either fly off into
Speaker 1: space or fall into the Sun exactly.
Speaker 2: Essentially, it's like a three body system, which we've talked
Speaker 2: about before, is fundamentally chaotic. The only arrangement for a
Speaker 2: three body system to be stable is if two of
Speaker 2: those bodies are pretty close together and pretty far from
Speaker 2: the third body, which is like, if you have a
Speaker 2: distant planet with the moon orbiting it, that planet gets
Speaker 2: too close to the Sun, you now have a three
Speaker 2: body problem and you're going to lose your moon.
Speaker 1: So you're saying that's kind of a problem because our
Speaker 1: exoplanet detection methods depend on being close to the Sun.
Speaker 1: But those planets might not have any moons exactly.
Speaker 2: So the kind of planets we're good at finding are
Speaker 2: the kind of planets we expect to not have very
Speaker 2: many moons. On the other hand, there's lots of planets
Speaker 2: out there, and we can sometimes see planets a little
Speaker 2: further from their star, and maybe one of those hot
Speaker 2: jupiters will have a big enough moon that's orbiting close
Speaker 2: enough to it to be stable. So there's not no hope.
Speaker 2: But it's pretty tricky.
Speaker 1: But I thought the transit method, the one where we're
Speaker 1: looking for eclipses and distant stars, those don't depend on
Speaker 1: the closeness of this planet.
Speaker 2: They do indirectly depend on the closeness of the planet.
Speaker 2: What you want is a short period, because you want
Speaker 2: to see many transits. If your planet is really far
Speaker 2: from your star and orbits like once every eighty years,
Speaker 2: then you're most ever going to see one transit, And
Speaker 2: it's pretty hard to be sure that what you're looking
Speaker 2: at is a planet if you only see one eclipse.
Speaker 2: If you see it regularly and it happens every four days,
Speaker 2: and you can really study it in detail, and you
Speaker 2: can convince yourself that you're seeing a planet, not for example,
Speaker 2: like a star spot, something on the surface of the
Speaker 2: star that's dimmer and darker and decreasing the intensity of
Speaker 2: the light.
Speaker 1: The period of the orbit makes a big difference.
Speaker 2: Yeah, exactly, because you want more examples.
Speaker 1: Right right, Yeah, Like some of the planets in our
Speaker 1: Solar system take like two hundred years right to go
Speaker 1: around the.
Speaker 2: Sun exactly, And so if you're an alien graduate student
Speaker 2: and you're trying to discover Pluto in our Solar system,
Speaker 2: then you're going to be a student for a long
Speaker 2: long time.
Speaker 1: Yeah, it's going to take even longer to get that
Speaker 1: PhD thousands of years.
Speaker 2: I hope you guys live long out there.
Speaker 1: So then what about direct imaging, like taking a direct photograph?
Speaker 1: Is in that better for planets that are far away
Speaker 1: from the star.
Speaker 2: Yeah, that's possible. We're sort of just on the cutting
Speaker 2: edge of being able to do that even for planets,
Speaker 2: and so we're pushing those limits and we're developing new
Speaker 2: technologies and this whole new generation of space based telescopes
Speaker 2: that are gonna be super awesome at doing direct imaging
Speaker 2: of those planets, and so as that gets better, it'll
Speaker 2: start to be possible to potentially see moons around those planets.
Speaker 2: But you know, as we said, like currently planets are
Speaker 2: basically one or two pixels, so resolving a moon around
Speaker 2: those planets would be really challenging. With a couple of exceptions,
Speaker 2: if those moons have ways to like really make themselves known,
Speaker 2: then we might be able to see them.
Speaker 1: So Like, for example, if you look at Jupiter here
Speaker 1: in our Solar system with a regular telescope in your backyard,
Speaker 1: you can actually see the moons of Jupiter, right. You
Speaker 1: see little points around the bigger circle of the planet.
Speaker 1: It is that if you point a bit powerful enough
Speaker 1: telescope and these distant planets, you could see maybe the
Speaker 1: dot front the planet, but also maybe little dots around
Speaker 1: it that might be the moons.
Speaker 2: Yeah, you might, especially if those moons are weird in
Speaker 2: some way, Like if those moons are super volcanic and
Speaker 2: they're shooting out really hot gases, you might be able
Speaker 2: to spot that. Or if the moon munds are super
Speaker 2: duper hot, like they're squeezed by their planet with tidal
Speaker 2: forces so that internally they're very high temperature, then they
Speaker 2: might glow at a different temperature than their planet and
Speaker 2: be easier to see them, and so there's some weird
Speaker 2: kind of moons that you might be able to direct
Speaker 2: image before regular normal humps of rock. But I think
Speaker 2: we're gonna have to wait for our direct imaging technology
Speaker 2: to improve significantly before we can expect to see pixels
Speaker 2: from exo moons.
Speaker 1: Interestingly, I wonder if you can like do like the
Speaker 1: cliffs method on a planet that's far away, you know
Speaker 1: what I mean, Like if if you're looking at the
Speaker 1: life from reflected from a planet and you see a
Speaker 1: dip itself, I wonder if that could be a sign
Speaker 1: that there's the moon there.
Speaker 2: Yeah, that's a cool idea. And you're right, the reflected
Speaker 2: life from that planet should dip when the moon passes
Speaker 2: in front of it. Again, we're still at the cutting
Speaker 2: edge of even seeing pixels from those planets, and so
Speaker 2: there you'd need like to study those pixels over time
Speaker 2: and to look for dips and to understand every other
Speaker 2: possible source of dips. Because that planet is light, is
Speaker 2: already going to be variable as the planet goes around
Speaker 2: the star, So you're gonna have to understand that and
Speaker 2: then variations on that. But yeah, that's a cool idea.
Speaker 1: Thanks, I'll take the Noble Price. We have it on record.
Speaker 1: All right, Well, these seem like long shot sort of
Speaker 1: sounds like from what you're saying that we're not super
Speaker 1: close to being able to do this. But have we
Speaker 1: have we found any moons out there and other planets?
Speaker 1: Have there been any discoveries?
Speaker 2: So we are right on the edge of being able
Speaker 2: to do this, which means that we have like a
Speaker 2: couple of candidates that are disputed. There are some people
Speaker 2: who think these probably are exo moons and other people
Speaker 2: who think they're probably not. You know, the evidence is
Speaker 2: like really right on the edge, and people split over
Speaker 2: the statistical analysis of these things. But it's fun because
Speaker 2: we have a couple of things to dig into and
Speaker 2: to talk about.
Speaker 1: All right, let's do it. What are these candidates for
Speaker 1: possible exomoons?
Speaker 2: So there was one discovered in twenty eighteen. This is
Speaker 2: the first exo moon candidate, and it's around planet Kepler
Speaker 2: sixteen twenty five B. Kepler sixteen twenty five is the star,
Speaker 2: B means the planet, and then the moon is called
Speaker 2: Kepler sixteen twenty five B. Dash.
Speaker 1: I Well, why I was there an abcd FGH moon
Speaker 1: or are they're just going for like an iPhone reference here.
Speaker 2: No, I think it's Roman numerals, Like the first one's
Speaker 2: going to be I, the second one's going to be II,
Speaker 2: the third one would be III.
Speaker 1: This kind of thing, uh I see, all right, Yeah,
Speaker 1: switching it up exactly.
Speaker 2: And so here's this two separate, independent pieces of evidence
Speaker 2: that suggests that there might be a moon here. What
Speaker 2: we're looking at is a Jupiter size planet around the
Speaker 2: star right, but it's like earth distance from the Sun,
Speaker 2: but it's like a huge planet.
Speaker 1: That's what we think is there.
Speaker 2: That's what we think is there. That's the planet that
Speaker 2: we're pretty sure is there. That's Kepler sixteen twenty five B.
Speaker 1: It's mass, but maybe not necessarily it has to be
Speaker 1: gas giant, does it.
Speaker 2: We know some of about it's mass because we know
Speaker 2: it's orbit and so we know roughly its volume, and
Speaker 2: we know it's roughly it's mass, and so we can
Speaker 2: tell something about the density. And these planets of this
Speaker 2: size are almost always gas giants.
Speaker 1: All right. So that's what we think is there.
Speaker 2: And so it's sort of an unusual planet already because
Speaker 2: it's a cool Jupiter. We talked earlier about how lots
Speaker 2: of the planets we've discovered are hot Jupiter's big planets
Speaker 2: very close to their star, like within the orbit of Mercury,
Speaker 2: you know, but this is farther out orbit makes it
Speaker 2: a cool Jupiter. And the first thing they noticed is
Speaker 2: this transit timing variation that the planet is blocking the
Speaker 2: light from the star behind it. But it's not in
Speaker 2: a regular fashion. There're wiggles there and exactly the way
Speaker 2: you would expect if there.
Speaker 1: Was a moon, I see. So it's not like going
Speaker 1: around its Sun in a regular way. It has a
Speaker 1: little wiggle to its orbit exactly.
Speaker 2: It has a little wiggle to its orbit, which can
Speaker 2: be explained very nicely by the presence of a moon.
Speaker 2: Like they do all the statistical calculations, they have two
Speaker 2: models like with and without the moon, and the one
Speaker 2: with the moon better explains the data, like much much
Speaker 2: better explains the data than the model without the moon.
Speaker 1: Although couldn't it be something else as well?
Speaker 2: It could be something else, right, It could be that
Speaker 2: there are other planets in this solar system and those
Speaker 2: planets are tugging on it, and that'd be much more
Speaker 2: complicated because you could have multiple planets like several Jupiter
Speaker 2: sized planets that are yanking on it. It's very difficult to model.
Speaker 2: And that's one reason why this is not a smoking
Speaker 2: gun discovery, because there are other ways that you could
Speaker 2: get this kind of signature. What they did follow up
Speaker 2: is they looked at some Hubble data. They looked at
Speaker 2: Hubble data pointed at this star to see if they
Speaker 2: could see an impact of the Moon on the transit itself,
Speaker 2: not just the timing, but like, could we see wiggles
Speaker 2: in the dip right? Are there like shoulders in this
Speaker 2: transit that indicate that we're seeing like a moon rise
Speaker 2: as the planet is blocking the light from the star.
Speaker 1: Like, is the moon from this cool Jupiter also blocking
Speaker 1: the light from the star Sometimes.
Speaker 2: Yeah, exactly. And we only have unfortunately, one really clear
Speaker 2: transit because this comes from Hubble, and Hubble is not
Speaker 2: a planet finding telescope. It's busy doing lots of things.
Speaker 2: It's not always looking at one star. So they have
Speaker 2: only like forty hours of data from this star with Hubble.
Speaker 2: But they did see a clear transit and there is
Speaker 2: a dip there that looks like a Neptune size moon
Speaker 2: around this Jupiter sized planet.
Speaker 1: Whoa that would be a huge moon wouldn't it.
Speaker 2: Yeah, literally, that would be huge.
Speaker 1: More like a sister planet almost.
Speaker 2: Yeah, although technically if it's orbiting a planet, then it's
Speaker 2: a moon.
Speaker 1: But what if they're both planets.
Speaker 2: Yeah. This gets into a really murky territory of where
Speaker 2: you define things to be binary planets and where one
Speaker 2: of them is a moon. They have this definition where
Speaker 2: if the center of mass is inside the surface of
Speaker 2: one of them, then one of them is a planet
Speaker 2: and the other one is a moon. And in this
Speaker 2: case that Jupiter is so much bigger than the Neptune
Speaker 2: that the Neptune qualifies as a moon.
Speaker 1: You only have one data point. Why don't we get more?
Speaker 2: I think that people are excited about that and are
Speaker 2: working on it, But you know, hubble time is very
Speaker 2: very precious, and there's lots of good things to use
Speaker 2: hubble for. In the meantime, people have been like analyzing
Speaker 2: this and reanalyzing this, and other groups have analyzed this data,
Speaker 2: and not everybody agrees with the interpretation that the first
Speaker 2: paper came up with. Some people look at the transit
Speaker 2: data and they say, no, there's no dip there from
Speaker 2: a moon. It doesn't look like there's any shoulder there.
Speaker 2: Another group analyzed it and said they do agree with
Speaker 2: the shoulder, but they disagree with the uncertainties and the
Speaker 2: other measurements. And the point is that the data is fuzzy,
Speaker 2: it's not crisp and clear, it's not obvious. It requires
Speaker 2: like heavy duty statistical techniques to extract this information, and
Speaker 2: so we just really can't be one hundred percent confident.
Speaker 1: Wow. So they posted this paper with just one data point.
Speaker 2: Well, they have one example of the transit, but they
Speaker 2: also have the transit timing, right, So those are two
Speaker 2: independent streams of information. One is the timing of the
Speaker 2: transits and the other is like the actual photometric like
Speaker 2: looking at the dip in the light, seeing the moon
Speaker 2: itself actually eclipse. They have lots more of examples of
Speaker 2: the Moon tugging on the Jupiter and changing its transits,
Speaker 2: but only one example of the moon itself blocking the light.
Speaker 1: And they sort of match together. I guess right.
Speaker 2: They do match together according to one group and their analysis,
Speaker 2: and they don't match together according to another group.
Speaker 1: Sounds like they need more data.
Speaker 2: We definitely need more data. We need more telescopes and
Speaker 2: more eyeballs. It's so frustrating when our knowledge of the
Speaker 2: universe is just limited by like how many eyeballs we've built,
Speaker 2: because there's nothing stopping us from building more. It's just money.
Speaker 1: It's just money.
Speaker 2: It's just money.
Speaker 1: It needs money.
Speaker 2: We can just print more. Come on, let's do it.
Speaker 2: Print some more money, makes it more scope. Done, Let's
Speaker 2: do it. Hey, a lot of engineers will be put
Speaker 2: to work building the Daniel Fund the telescope.
Speaker 1: Yeah, I'm sure, I'm sure.
Speaker 2: Okay, I will print my own money and I'll see
Speaker 2: if engineers out there will accept it as payment one
Speaker 2: hundred thousand Daniel bucks.
Speaker 1: Well no, Well, I mean, if you commit fraud that way,
Speaker 1: who's going to believe your scientific findings?
Speaker 2: Yeah, exactly, And that's why there's no Daniel Space Telescope.
Speaker 1: All right, Well, what's another discovery we made in this
Speaker 1: attempt to find other moons?
Speaker 2: So there's a second potential discovery. This one's Kepler seventeen
Speaker 2: oh eight b dash I. And this was a really
Speaker 2: cool strategy to look specifically for planets that have long
Speaker 2: periods that are further away from their stars, because they're rarer,
Speaker 2: at least in our catalog. At least they're rare in
Speaker 2: the kind of things we can see, but they are
Speaker 2: more likely to have moons, we.
Speaker 1: Think, because that's kind of the trend in our Solar system, right,
Speaker 1: Like we have one moon Mars is two in the
Speaker 1: inner Solar System, but in the outer Solar System, like
Speaker 1: Jupiter and Saturn have dozens of moons.
Speaker 2: Yeah, exactly, because further you get away from your star,
Speaker 2: then the more freedom you have to like dominate your
Speaker 2: gravitational environment, capture moons or retain moons or all that
Speaker 2: kind of stuff. So they thought, well, let's focus on
Speaker 2: cool giants, these planets that are further away, and then
Speaker 2: the whole catalog of exoplanets we've ever discovered, they're only
Speaker 2: like seventy that qualify is these cool giants.
Speaker 1: I see. If they're not cool, they're not included in
Speaker 1: the study. You're not invited to the party. Only cool giants.
Speaker 2: Hot giants is a totally different party with a totally
Speaker 2: different vibe. Yeah.
Speaker 1: Here, it's more of a hipster you know scene.
Speaker 2: Yeah, we're listening to jazz around here, so sit down,
Speaker 2: have a drink, chill out.
Speaker 1: I'm not sure jazz is considered cool by the kids
Speaker 1: these days.
Speaker 2: All right, thanks for filling me in, all.
Speaker 1: Right, well, let's dig into this cool giant moon what
Speaker 1: we know about it and what it tells us about
Speaker 1: how solar systems form. But first, let's take another quick
Speaker 1: break or right, we're talking about cool giants, not the
Speaker 1: you know, plain old giants, not the lame giants, but
Speaker 1: the cool giants, and seeing if they have any moons
Speaker 1: in them. That's right, The moons have to be cool too.
Speaker 2: Some of these moons could be hot, right, they could
Speaker 2: be volcanic, They can have all sorts of stuff going
Speaker 2: on inside. Even if the planet itself is pretty.
Speaker 1: Cool, that would be cool, all right. So we've been
Speaker 1: talking about finding moons and other planets outside of our
Speaker 1: Solar system in distant stars, and there are many different
Speaker 1: ways to do it that are getting better and better
Speaker 1: every day. And so we have a couple of candidates
Speaker 1: of things that might be moons exo moons out there,
Speaker 1: and one of them is this one called seventeen oh
Speaker 1: eight b I.
Speaker 2: That's right, and this one was just discovered last year,
Speaker 2: twenty twenty two. And they looked again at the transits
Speaker 2: they're looking for like shoulders when this planet is going
Speaker 2: around the star, are there moments when it's blocking more
Speaker 2: light than you expect, which could be explained by having
Speaker 2: a moon orbiting that planet and like rising past the
Speaker 2: limit of the planet or coming around the back and
Speaker 2: blocking the light. And so they were looking for these
Speaker 2: little shoulders, and it's really pretty cool they do see
Speaker 2: some they see these little shoulders inside this transit lip.
Speaker 1: And I think by shoulder you mean like if the
Speaker 1: planet didn't have a moon, when it stopped making an
Speaker 1: eclipse with the star behind it, the light from the
Speaker 1: star would just drop off, or at least drop off
Speaker 1: relatively quickly. But if it has a little moon maybe
Speaker 1: trailing behind it, then the light from the star would
Speaker 1: go down mostly but not all the way, but then
Speaker 1: a little bit of a shadow would remain, and then
Speaker 1: the shadow would go away. And that's the kind of
Speaker 1: thing you're looking for. Right.
Speaker 2: There's a moment after which the planet is no longer
Speaker 2: blocking the star, but the moon might be blocking it
Speaker 2: a tiny little bit all by itself, which extends this
Speaker 2: transit dip.
Speaker 1: Or maybe the moon isn't like in front of the planet,
Speaker 1: and so then first the moon gets out of view
Speaker 1: of the star, and then the planet drops out of
Speaker 1: the eclipse, and so you see this little shoulder in
Speaker 1: the light from.
Speaker 2: The star exactly, and so they see this shoulder and
Speaker 2: they can explain it using again a Neptune size moon.
Speaker 2: This planet has a Mars like orbit, so it's even
Speaker 2: further from its star than the previous one. And the
Speaker 2: planet itself is huge. It's five times the massive Jupiter,
Speaker 2: so it's a really big planet with a Neptune size
Speaker 2: moon candidate. And the only explanation we have for these
Speaker 2: shoulders is an exo moon. There's no other explanation other
Speaker 2: than like just random noise, you know, maybe it's just
Speaker 2: fluctuations in the data. And they've done a statistical calculation
Speaker 2: and that seems unlikely to like one part in one
Speaker 2: hundred or so, so it's not like smoking gun evidence again,
Speaker 2: but it's a pretty nice signature of what could be
Speaker 2: a Neptune sized exo moon.
Speaker 1: And we have more than one data point here in
Speaker 1: this case.
Speaker 2: Yeah, we have more than one shoulder. They've seen several
Speaker 2: transits of Kepler seventeen oh eight.
Speaker 1: And it always has this little shoulder, or would you
Speaker 1: expect it to sometimes have a shoulder sometimes not have
Speaker 1: its shoulder because the moon is kind of going around
Speaker 1: the planet.
Speaker 2: Right exactly, So you expect the shoulder to vary, and
Speaker 2: they see it vary and just this way you would
Speaker 2: expect for a moon, right, it has the right wiggles
Speaker 2: at the right time.
Speaker 1: H Like, if you assume this, this moon, this neptum
Speaker 1: sized moon, is going around every month, and you see
Speaker 1: it in a monthly way in the orbit of the
Speaker 1: planet around the start exactly.
Speaker 2: And in this case they're able to calculate the orbit
Speaker 2: of the moon around the planet and has a period
Speaker 2: of several days, and so they factor that into their model.
Speaker 2: They have this mathematical model that says, here's the star,
Speaker 2: here's the planet, here's the moon going around it. When
Speaker 2: should we expect to see dips from just the planet,
Speaker 2: from the planet plus the moon. From just the moon.
Speaker 2: They can use that to predict very precisely the light
Speaker 2: curve they expect to see, and it all lines up.
Speaker 2: I mean in reality, they've done it in reverse. They've said,
Speaker 2: what mathematical model of that solar system would explain the
Speaker 2: dips that we see? And the cool thing is that
Speaker 2: they can't explain it, and they can only explain it
Speaker 2: with a model that includes a moon.
Speaker 1: Pretty cool. Can they tell how far away. This moon
Speaker 1: is from its planet, from the shoulders with or the
Speaker 1: size of the shoulder. That must be how they're estimating that,
Speaker 1: is its neptune size or is it from how the
Speaker 1: light dips.
Speaker 2: It's definitely from how the light dips. The period comes
Speaker 2: from when those dips happen. So yeah, you can estimate
Speaker 2: the volume of that moon and the period of that moon.
Speaker 1: Cool. Well, was that a big deal when they discover
Speaker 1: this or is this still something they're confirming this?
Speaker 2: There's definitely something they're confirming. Nobody's like one hundred percent
Speaker 2: sure that this is an exomoon. It's like in the
Speaker 2: candidate stage, and they're planning to observe more with Hubble
Speaker 2: and with James Webb and with other devices. The next
Speaker 2: transit of this planet in the star was in March
Speaker 2: of this year, and so I hope that they got
Speaker 2: some data and they're analyzing it now.
Speaker 1: Yeah, as we speak, it might be confirming this right now.
Speaker 2: And as more data comes in from more cool giants
Speaker 2: or more exoplanets, we're going to see more and more
Speaker 2: hints of exo moons, until eventually this goes from like
Speaker 2: maybe tentative discovery to like we are drowning in exo moons.
Speaker 2: They're everywhere. You know, people who get their PhD and
Speaker 2: like a single tentative discovery are going to be amazed
Speaker 2: when ten years later people are doing their PhDs with
Speaker 2: thousands of candidates.
Speaker 1: Oh, man, I guess that's how it went with exoplanets, right,
Speaker 1: Like people for work for a long time just to
Speaker 1: find one exoplanet, and then as the technology and the
Speaker 1: techniques got better, and now they're finding them by the thousands.
Speaker 2: Yeah, exactly. Now people are doing like statistical analysis, you know,
Speaker 2: distributions of planet sizes. They're looking at trends in these
Speaker 2: planets to try to understand what it means about how
Speaker 2: solar systems form. And so right now or at this
Speaker 2: very exciting moment, we're on the cusp of being able
Speaker 2: to see these exo moons, and we know that as
Speaker 2: technology improves in the future, we're going to be able
Speaker 2: to ask and answer really interesting questions like how common
Speaker 2: is it to have hundreds of moons in a solar system,
Speaker 2: or to have moons whose relative size is so big
Speaker 2: compared to the planet like ours is.
Speaker 1: I guess that's the big goal, right, is to compare
Speaker 1: other solar systems to ours. It's like our most solar
Speaker 1: system out there like ours, or is ours weird? And
Speaker 1: if it's weird, why is it weird? Right?
Speaker 2: Yeah? And is that weirdness crucial for life or maybe
Speaker 2: it hindered life here in our Solar system and made
Speaker 2: it less likely? Right? Maybe life is really really common
Speaker 2: in the universe and we relate to get started because
Speaker 2: we have a weird moon or not enough moons or
Speaker 2: too many moons or something. What we know is that
Speaker 2: they're going to be surprises. Like when we started discovering exoplanets,
Speaker 2: we were surprised by what we found. Our models of
Speaker 2: how the Solar System formed have been completely upended by
Speaker 2: our discoveries about exoplanets and exo moons. I'm sure will
Speaker 2: also have lots of surprises.
Speaker 1: Yeah, Like it was a big surprise how many exoplanets
Speaker 1: there are out there, right, especially the ones that are
Speaker 1: like Earth.
Speaker 2: Yeah, exactly how many hot jupiters there were. And the
Speaker 2: diversity of moons in just our Solar system is crazy, right.
Speaker 2: We have moons that were formed with planets, we have
Speaker 2: moons that were captured, moons made had a weird stuff,
Speaker 2: moons that might have come from collisions. They're probably a
Speaker 2: whole other ways to make moons we haven't even thought
Speaker 2: of because they don't exist in our solar system. The
Speaker 2: diversity of exo moons is going to be really, really wild.
Speaker 2: There's going to be some weird stuff out there.
Speaker 1: And moons have a big impact on life itself, right,
Speaker 1: Like think about how much of life on Earth is
Speaker 1: sort of sync to the lunar calendar.
Speaker 2: Yes, some people speculate that having such a big moon
Speaker 2: with its dramatic tides could have had a big impact
Speaker 2: on the formation of life here on Earth. People think that,
Speaker 2: like in the brackish water between the fresh water and
Speaker 2: the salt water, that the sloshing around and the mixing
Speaker 2: up of all those chemicals and the primordial soup might
Speaker 2: have really helped life form, And so having the moon
Speaker 2: there with its big dramatic tides could have been a
Speaker 2: big boost to the formation of life. It might be
Speaker 2: that it's crucial to have such a big moon. That'd
Speaker 2: be really fascinating. Right if we found life in other
Speaker 2: solar systems and in every case they had a weirdly
Speaker 2: big moon.
Speaker 1: Whoa, we might have the moon to sign for being here.
Speaker 2: Exactly or it might be that mostly life is on moons, right,
Speaker 2: that maybe moons are a better place to have life
Speaker 2: than actually the surface of the planet. You know, we
Speaker 2: think that for example, under the ice in Europa or
Speaker 2: inside Io or on Ganymede, there might still be life
Speaker 2: in our solar system. So it might be even in
Speaker 2: our solar system that it's rare for life to start
Speaker 2: on a planet compared to moons.
Speaker 1: Yeah, it might be that life is over the moon.
Speaker 1: About having a moon, and that.
Speaker 2: Joke exactly, and people have really fun about how life
Speaker 2: can evolve on these moons, using like the planetary magnetic
Speaker 2: field as a shield from cosmic rays and being close
Speaker 2: to the star but avoiding being tightly locked to the star.
Speaker 2: There's all sorts of reasons why life could form on
Speaker 2: a moon. And because there are so many more moons
Speaker 2: than planets, we think that means even more places for
Speaker 2: life to start.
Speaker 1: Right, Right, All the moons harder to have an atmosphere
Speaker 1: because they're smaller, are.
Speaker 2: Smaller, so it's harder to have an atmosphere. But you
Speaker 2: could have life within those moons, right, You could have
Speaker 2: underwater oceans. Most life in the universe might be under
Speaker 2: ice crusts.
Speaker 1: Whoa, they might be cooler than us, or more most
Speaker 1: certainly they are cooler than us, at least us here
Speaker 1: on the podcast.
Speaker 2: They might have no concept of the universe. Right, If
Speaker 2: you form in a dark ocean, you can't even access
Speaker 2: the sky, Right, you'd have to somehow drill a hole
Speaker 2: in that ice and climb out before you even know
Speaker 2: that the rest of the universe is there. What a
Speaker 2: crazy mind shift that would happen to be.
Speaker 1: Well, there might be like how we thought about the
Speaker 1: Earth of the universe before, Right, we thought there was
Speaker 1: a ceiling. Basically, they might actually have a ceiling.
Speaker 2: They might literally have a ceiling exactly.
Speaker 1: Well, hopefully they'll blow the roof off with that bit
Speaker 1: of science there.
Speaker 2: We're always in awe of everything we discover and always
Speaker 2: surprised by what the universe has in store for us.
Speaker 1: Yeah, because I guess scientists are always aiming higher. They're
Speaker 1: always getting more and more ambitious. In other words, they're
Speaker 1: always shooting for the moon. All right, Well, we hope
Speaker 1: you enjoyed that. Thanks for joining us, See you next time.
Speaker 2: Thanks for listening, and remember that Daniel and Jorge explain
Speaker 2: the universe is a production of iHeartRadio. We're more podcasts
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