Could we see moons around exoplanets?

00:00:08
Speaker 1: Hey, Daniel, do you ever worry about the ethics of using a telescope?

00:00:12
Speaker 2: What do you mean? What are the ethical questions about looking through a telescope?

00:00:16
Speaker 1: I mean, like what they're looking at?

00:00:17
Speaker 2: Well, I'm not pointing them at my neighbor, if that's what.

00:00:19
Speaker 1: You mean, not your next door neighbor. What about your next galaxy neighbor.

00:00:23
Speaker 2: Are you asking if we have the right to look at distant objects in the sky?

00:00:28
Speaker 1: Yeah, you know, like what if there are aliens there on a planet or a moon and we're like spying on them?

00:00:34
Speaker 2: Well, I hope they're not offended if we catch them sunbathing or I guess starbathing.

00:00:38
Speaker 1: Aren't all stars suns? But yeah, don't you think aliens have a right to privacy?

00:00:42
Speaker 2: I don't know. Maybe they're alien celebrities, so they're like starbathing stars.

00:00:47
Speaker 1: Wait, are you saying celebrities can have privacy either? Are you secretly a starker?

00:00:52
Speaker 2: No, I'm saying astronomers are just interstellar paparazzi.

00:00:56
Speaker 1: Well, oh, it sounds like they need to draw their curtains more. Why just have you don't get the rest of us punch in the face, Hi am horhem a cartoonist and the author of Oliver's Great Big Universe.

00:01:20
Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor at u C Irvine. And if it gets the aliens to come, I want them to punch us in the face.

00:01:29
Speaker 1: Us in the face. How about just you in the face? I mean, please, don't volunteer my face for your science.

00:01:36
Speaker 2: Us volunteering humanity's collective face.

00:01:41
Speaker 1: Some of us are sensitive in the face.

00:01:43
Speaker 2: It might be worth a puncher too, to learn that we're not alone in the universe.

00:01:46
Speaker 1: Can we pick where they're going to punch us, you know, like when you're playing as kids.

00:01:50
Speaker 2: You mean in the Daniel part of the face, rather than the joey part of the face.

00:01:54
Speaker 1: Definitely the Daniel part. But anyways, Welcome to our podcast, Daniel and Jorge Explain the Universe, a production of iHeartRadio.

00:02:02
Speaker 2: In which we try to teach you all about the mysteries of the universe, rather than punching you in the face with them. We think that it's possible to gently absorb all of the crazy intricacies of how the universe works, from its tiny little particles to its mysterious swirling black holes. Without getting bruised, basically anywhere on your body. We seek to serve up the mysteries of the universe in a gentle and comfortable manner.

00:02:26
Speaker 1: That's right. We bring you the one two punch of science and bad dad jokes to talk about all the amazing things that are happening in the universe, all the peaceful things and also all of the combatitive things, and.

00:02:37
Speaker 2: The mysteries that we love to dig into. Are the ones that tell us about our context in the universe. Is where we are in the universe weird and unusual? Or are there many such backyards with many such podcasts giving all the same dad jokes?

00:02:51
Speaker 1: Yeah, that has been one of the biggest questions in the universe is are we alone in the universe? Or are we one of many many alien civilization out there in space? And are we the only ones making dad jokes?

00:03:04
Speaker 2: And how many of them are spying on us while we're sunbathing in our backyards.

00:03:08
Speaker 1: Well, I guess you know, technically, in an infinite universe that there's probably a planet out there where dad jokes are like the epitome of intelligence and literature.

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Speaker 2: Are you saying that's not our universe? Are you saying that's not our planet.

00:03:20
Speaker 1: That is definitely not. I think there's a reason they're called dad jokes, not just jokes. But maybe there's an alien species out there where you know, it's like the height of width, you know.

00:03:30
Speaker 2: Right, Well, we should try to sell our books on that planet then, because we have a lot of readers.

00:03:36
Speaker 1: Yeah, would be intergalactic bestsellers, not just international bestsellers.

00:03:40
Speaker 2: But we're not just interested in whether our books will sell to alien species. We're interested in whether there are aliens out there, whether life exists in other parts of the galaxy. And part of that question is asking whether our whole setup is unusual. Are there stars with planets around them? Do those planets have similar conditions to the planets here? Is there something weird and strange about the Solar System? Or is it very common?

00:04:05
Speaker 1: Yeah? Is the planet Earth a rare gem that exists out there in the cosmos or is it sort of like a you know, cheap chot sky that you can find anywhere.

00:04:13
Speaker 2: In just a few decades ago, we didn't know the answers to basic questions like are there planets around other stars? Fortunately, as we develop new and more powerful eyeballs, We've been able to discover those planets, and now we are pushing further. We are asking deeper and more subtle questions about the nature of those planets, their atmospheres, their surfaces, even what's in orbit around them.

00:04:35
Speaker 1: So today on the podcast, we'll be tackling the question could we see moons around exo planets? Now, Daniel, I imagine these are like moons, like the orbiting celestial bodies, and not like aliens mooning.

00:04:53
Speaker 2: Or maybe alien death stars. Right, we don't care. We just wanted to discover them.

00:04:58
Speaker 1: Wait wait, wait, wait, I think we maybe should. If there are alien death stars, maybe we don't want to meet them. Maybe these are not the aliens we're looking for.

00:05:06
Speaker 2: I think we'd rather know they're there than live in ignorance, wouldn't we.

00:05:10
Speaker 1: If we know they're there, then they know we're here.

00:05:12
Speaker 2: We could just use that Jedi mind trick, that's.

00:05:13
Speaker 1: Right, make them forget and dazzle them with our dad jokes and then it'll be like what what And then they won't want to associate with us, and then problem solve.

00:05:22
Speaker 2: These aren't the jokes you're looking for.

00:05:24
Speaker 1: That's right, or they'll want to annihilate us right away, But.

00:05:28
Speaker 2: We are curious about the environments of these planets. Having moons affects life on Earth and tells us a lot about the history of that solar system, and just in general, we want to know, like our solar system is pretty mooney, are other solar systems mooney as well?

00:05:43
Speaker 1: Mooney and wonderful? Because I think, as you said earlier, up until a little bit a few years ago, a few decades ago, we didn't even have confirmation there were other planets out there, right, We just imagined or assume there were, but we had not actually seen any.

00:05:55
Speaker 2: Yeah, it could have been that we were one of very very few, perhaps singular solar systems that had planets around it. It could have been that the reason that there's life here around our Sun is that it was the only one with a rocky habitable perch. Now, of course, we know the opposite is true. We know there are planets all over the galaxy. We've seen a few thousand of them, and we estimate that there are zillions of them, that they're almost literally everywhere in the galaxy. That's a real change in the way we see our whole context in the universe.

00:06:26
Speaker 1: Yeah, because imagine even like jumping from our sun to the stars in the sky was kind of a big leap for humanity too, right, Like, we can look at our sun and it looks circular, at least if you see a projector of it or through a filter, you can see that it's a giant ball. But the stars in the sky just look like little pinpoints, And so it must have been a pretty big leap to think, you know, those pinpoints are actually stars.

00:06:45
Speaker 2: It is a pretty big leap. And to understand how big a leap it is to understand how far away they are is pretty tricky. I mean, even the Greeks knew that the other stars were likely suns, but they thought they were much much closer than they actually are. The Greeks couldn't understand how far away these stars actually were. So yeah, it really expands your whole mental picture of the universe to understand that our sun is one of many of those stars, and that therefore there are lots and lots of places where life might exist in the universe.

00:07:15
Speaker 1: Yeah, and those stars out there are really far away, that's why they look like pinpoints. And so basically, until recently, it was almost impossible to really see a planet on them, right.

00:07:24
Speaker 2: It was very tricky, and for a long time people thought it might be impossible. But astronomers are very clever and very hard working, and now we have lots of tricks to discover planets around other stars, and so now people are pushing into what many people believe is impossible, understanding the atmospheres, the surfaces, and maybe even the orbiting bodies of those planets.

00:07:46
Speaker 1: I wonder what did I'm sure we'll get into it, But what's the driving question here to know whether an exoplanet has a moon? Like do you think maybe the moon is the one that's habitable, or you're just trying to study other moons?

00:07:57
Speaker 2: I think all of those things. Moons might be the most commonplace for life in the universe. It might be that moons around big planets are the best place for life to evolve, and the humanity is very, very weird for developing directly on the surface of a planet. On the other hand, moons also tell you a lot about the history of the Solar System, how it formed, how it came to be, which tells you a lot about where you expect to find planets that might have life on them. So it's as much about understanding the detailed history of other solar systems and thinking about where we might find life well as usually.

00:08:31
Speaker 1: We were wondering how many of you out there had thought about this question and wondered if we could see moons in other planets.

00:08:37
Speaker 2: Thanks very much to everybody who offers their unprepared insights. We really enjoy this segment of the podcast and we want to hear from you. Please don't be shy write to us to questions at Danielandjorge dot com.

00:08:49
Speaker 1: So think about it for a second. Do you think we could ever see moons around exoplanets? Here's what people have to say.

00:08:56
Speaker 3: Just finished listening to the podcast with the exoplanet researcher and do I think we could see them? No, but we do have confirmed existence of moons around exoplanets. I believe that number is currently at two.

00:09:10
Speaker 4: I think we will definitely be able to see moods throughout exoplanets. James Web will be able to analyze the atmospheres of exoplanets and it might even be strong enough to see moons. And if not, James Web, there's probably going to be another set of eyeballs in the future that we'll be able to do it.

00:09:26
Speaker 5: I think that in order to be able to detect moons of exoplanets, we would need very sensitive telescope and other instruments capable of measuring the lightest, faintest of changes in the light emitted from other stars.

00:09:43
Speaker 6: Yes, in terms of finding excello planet moons to be to measure the gravity between that planet, that exoplanet a star and see if we can account for any extra gravity that would be from the moon or maybe some sort of nudger or tug on that moon.

00:09:58
Speaker 7: I think this depends on your definition of what it means to see a moon. It seems like it would be nearly impossible to imagine directly imaging any especially given that we haven't directly imaged and exo planet yet. But if we had a specially large planet around a star with a big enough percentage of its star's mass, and if it in turn had a moon that was a significant percentage of its mass, then I would imagine that they could probably detect the combined wobble of the interaction between those three.

00:10:25
Speaker 1: All Right, a lot of optimism here. I feel everyone's like, sure, yeah, eventually, sort of in one way or another, Yeah.

00:10:31
Speaker 2: There's this bubbling sense that eventually we could figure out basically any problem that in our future lies more and more powerful techniques and telescopes and smarter people that could extract this kind of information from the universe. I love that it's so inspiring to hear people's optimism. Yeah.

00:10:47
Speaker 1: Yeah, And I think by smarter people you mean the engineers, right.

00:10:51
Speaker 2: I mean my students and my students'.

00:10:53
Speaker 1: Students and the engineers that actually do it for them, right. I think that's what you're saying.

00:10:57
Speaker 2: Right, I know, we just submit the work order and it comes back. You know who knows who does YadA, YadA YadA. You gotta telescope.

00:11:03
Speaker 1: That's right, We toy anonymously. That's what happens to all smarter people.

00:11:07
Speaker 2: No, of course, the field of astronomer is filled with people who analyze the data, and people who build the devices, and people who plan for the next generation of devices. It's a whole ecosystem of smart people, from physicists to planetary scientists, to engineers to computer scientists, all sorts of people all working together.

00:11:24
Speaker 1: Well, this is a pretty big question, or I guess a small question is how do you see the moon around a planet orbiting a star that is light years or at least millions of miles away. It's a pretty tough question.

00:11:36
Speaker 2: It is a pretty tough question, and it's going to require us to get even better at seeing those planets. All the techniques we have for seeing moons are basically like super powerful versions of the ways that we see planets.

00:11:49
Speaker 1: All right, well, let's break it down for people, Daniel. First of all, what is an exoplanet and what do we know about them?

00:11:55
Speaker 2: So an exoplanet is very simply just a planet around another star. Planets are the planets around our sun. An exoplanet is a planet around for example, Alpha Centauri or any other star that's not our Sun XO. Just meaning like outside the Solar system.

00:12:11
Speaker 1: M I see like an outer planet? Where I guess not, because an outer planet could be the planets in our Solar system. Like anything outside of our Solar system that's a planet is an exoplanet.

00:12:21
Speaker 2: Yeah, a planet around another star would be an exoplanet. And they have to be far away because the nearest star is several light years away, which is really really far. It's very far compared to the distance between the planets, and so an exoplanet is going to be very, very different from any planet in our Solar system, just in terms of like where it is.

00:12:40
Speaker 1: And we hadn't actually seen one or confirmed there were any planets around any other stars until basically like thirty years ago.

00:12:47
Speaker 2: Right, Yeah, it's incredible if you make a plot of like the number of planets we've seen over time, dating back like thousands of years until fairly recently, we'd only ever seen like six, right, and then Urinus and Neptune are discovered in the last few hundred years, and then Pluto and then un Pluto, so we're back down to eight. And then it wasn't until the nineteen nineties, only thirty years ago, that we finally saw one outside of our Solar system. Until then, we only speculated, we only imagined, we'd had calculations, we had speculations, but we had no actual data until about thirty years ago when we developed these techniques to see the planets or to deduce their existence around other stars.

00:13:26
Speaker 1: Yeah, because, as one of the listeners who replied earlier said, the word see is a little bit tricky, right, We didn't actually see planets in other stars. We sort of like figure out they were there, but we didn't actually see them.

00:13:37
Speaker 2: Yeah, exactly, and so we have these really cool techniques to deduce that they exist, and you know, you can argue philosophically about what does it mean to see something, But we didn't see exoplanets directly until much more recently. The first discoveries came from just observing the impact of those planets on the stars, which of course we can.

00:13:57
Speaker 1: See, which is kind of crazy to think, right, because what possible impact and the Earth have on the Sun. The Sun is like a million times heavier than the Earth, right or more.

00:14:06
Speaker 2: It's all about making these things more sensitive and getting down to the details. Like mostly you're right, the Earth has basically no impact on the Sun. But if you analyze the Sun super duper closely, then yeah, the Earth does have a little bit of an impact on the Sun, the same way that, for example, the other planets have an impact on the Earth. Mostly, the Earth's orbit around the Sun is just a story of two bodies, the Earth and the Sun, orbiting their combined center of mass. But if you get super dup or precise about it, then you have to take into account, like the effect of Jupiter and Saturn on the orbit of the Earth. So all of these little complications can actually reveal the rich structure of the Solar system if you study them with enough precision.

00:14:45
Speaker 1: It's pretty mind body to think. I mean, the Sun is so big and it's the Earth is just this tiny little marble next to it, like that it would have an effect on the whole thing. Like I can see maybe pulling a little bit more on the part of the Sun that's closest to the Earth, maybe some of that cosma, But to think that it could move the entire Sun is pretty hard to believe.

00:15:03
Speaker 2: Yeah, Well, imagine instead you had two objects that had the same mass, right, like two stars the same mass, and they're orbiting each other. Clearly they have an effect on each other. What they're orbiting is actually a point right in between them. Now, as you shrink one of those things down and grow the other one so it becomes asymmetric, the points they're orbiting moves towards the center of the heavier one. If one of them was infinitely massive or the other one was massless, then they would both be orbiting a point at the center of the biggest object. But if the Earth is not massless, if it actually does have some mass, then it's pulling that center of mass a little bit away from the center of the Sun. And if you measure the motion of the Sun very precisely, you can detect that. And that's why these things are so hard. That's why it took so long to see these things, is that it requires really precise measurements now of the motion of stars in other solar systems.

00:15:53
Speaker 1: Yeah, it's pretty mind blowing. But I guess maybe one thing that helped was that we didn't start looking for Earth sized planets, right, we start looking for Jupiter sized planets.

00:16:02
Speaker 2: Well, we started looking for anything we could see, and we didn't know what was out there, right. We had speculation about what kind of planets might exist in other solar systems, but we didn't really know what we could find. You're right though, that the first techniques we developed were more powerful for Jupiter sized planets. The bigger the planet and the closer it was to the star, the easier it was for us to find them.

00:16:23
Speaker 1: Like, those were the first planets found right where. They were basically giant gas planets.

00:16:27
Speaker 2: Yeah, they call them hot Jupiters because they're the size of Jupiter and they're very close to the star. The closer they are the star, the faster the orbit, the easier it is to find them because they tug on the star. And so one of these techniques is called the radial velocity method. You look at the light from the star and you see if it's shifted in frequency. If a star is moving away from you, it's red shifted. If a star's moving towards you, it's blue shifted. If a star is getting wiggled by a planet that's orbiting it, then it's going to get red shifted and blue shifted, red shitted and blue shifted. It's going to wiggle a little bit in its frequencies. And that's what they look for. But that's more powerful for big planets and planets that are close to their stars.

00:17:06
Speaker 1: But then we develop other ways to look at planets, right really quick, What are some of these other ways that we can see exoplanets.

00:17:12
Speaker 2: So another way is the transit method, which is basically an eclipse. As the planet passes in front of the star, it dims it a little bit, it blocks some of the light. And so again if you're just measuring the light from the star roughly, you're never going to notice this. If you make very precise measurements of the light from the star, you can see these dips and you can see the patterns. If the planet goes around many many times, you'll see the same pattern over and over again. Unfortunately, this one is also best at seeing big planets that eclipse the light more and close by planets that block more light from their sun and go around many times, so we can see many transits.

00:17:47
Speaker 1: Yeah, like if the Moon didn't reflect any light and you can see it in the night sky, you could still maybe every once in a while know it's there because it would block the light from the Sun. You would see an eclipse exactly.

00:17:56
Speaker 2: And there are techniques that will let you see planets that are further from the Sun, and these are actually the direct imaging ones. We can look at a solar system and we can block the light from the sun called the corona graph, a little thing that prevents the light from the star from getting into the telescope and only look at the stuff around it. And now we have powerful enough telescopes that you can actually see dots around those stars. So these are direct images of light from those planets, and those are most powerful at seeing planets that are far away from the star. There's the further they are from the star, the easier it is to tell them apart from the blinding light from the star itself.

00:18:30
Speaker 1: Yeah, it's like you basically put your thumb, like if you look up at the skuy you put your thumb over the star and then you see there are any other twinkles around it, right.

00:18:38
Speaker 2: Exactly, And so we have like a few pixels of light from these planets. Of course, the planets themselves are not glowing. It's all reflected light from their star. But you know, it bounced off the planet first, so it's just like looking at the planet the same way the Earth is illuminated by our sun.

00:18:53
Speaker 1: That's the closest we have of an actual picture of another planet, right, Like, I've seen the plots. They're a bit old right now. We've had these photos for fish seen hears or something like that.

00:19:01
Speaker 2: Yeah, they're getting better and better, but they're not great. I mean they're pretty fuzzy. If you took pictures of your kids like this, none of your relatives would be very impressed with your photography. It's like a few pixels here and there.

00:19:11
Speaker 1: Yeah, although my kids nowadays avoid getting their picture taken as I think most kids do, and so they're kind of a big blur anyways, And then what's the last kind of method we used to detect these exoplanets.

00:19:24
Speaker 2: The last technique is called micro lensing, and that's essentially using the planet as a lens to distort light from some other star. If there's light from another star behind the Solar system that's passing through that Solar system, then it can get bent around the planet. Because the planet, of course is massive and it changes the shape of space and so it can act like a giant lens. This is sort of similar to the way we can see dark matter in the sky by seeing its gravitational lensing. So here's called micro lensing because there's so smaller amount of lensing as the light passes around the planet.

00:19:59
Speaker 1: Yeah, you're seeing how the bends the light coming at you. And so those are the different ways that we can see exoplanets. But now the big question is are there moons around these exoplanets out there in the universe? What is it like on those moons, could we ever see them? And how are we going to see them? So let's dig into that. But first let's take a quick break. All right, we're talking about finding exo moons, So you call them exo moons if it's a moon around an exoplanet.

00:20:37
Speaker 2: Yeah, we call them exo moons unless you have a better name for.

00:20:40
Speaker 1: Them, turning to be like exoxo moons because it's like a different body out on an exoplanet.

00:20:48
Speaker 2: There are exo moons around exo planets. There are two exos there. But I think exo just means in another solar system.

00:20:55
Speaker 1: So well, what do you call the moons around Jupiter?

00:20:57
Speaker 2: Moons?

00:21:00
Speaker 1: Moons?

00:21:02
Speaker 2: Yeah, there you go, and no moons now, just moons. And you know, Jupiter is a great example because something we noticed and our solar system is there are kind of a lot of moons, right, we have two hundred and twenty six moons in our solar system. And something we wonder is like, is that weird? Are we kind of moony? Or are we moon poor compared to other solar systems? Like what's a typical number of moons to have? We just don't even know.

00:21:26
Speaker 1: And we have a whole episode about how like moons form, right, how you get a moon?

00:21:30
Speaker 2: Yeah, exactly. It's really fascinating the number of ways that you can get a moon, they can form with a planet, you can capture them, it can be the result of a collision. The point is that it tells you a lot about the history of the Solar System. It's like a record of what happened here before you showed up.

00:21:46
Speaker 1: Right, Like our Solar System we've talked about before, it was a pretty chaotic place, and so it kind of makes sense that there was just a lot of debris out there floating, flying around, and so not all of it was going to get into planets, and so it makes sense we have a smaller box that they're orbiting the bigger bodies.

00:22:02
Speaker 2: Yeah, although we have an incredible range of sort of size of those bodies. Like our moon is huge. It's like more than one percent the mass of the Earth, which is very very unusual. More typical size is like one ten thousands the mass of the planet. But then there's also like Sharon, which is one eighth the mass of Pluto, even though Pluto not officially a planet anymore. But we have this incredible variation in the sizes of the moons and in their origin and their composition. It's really an incredible diversity.

00:22:30
Speaker 1: Or I guess in the relative size, right, because some of the moons around Jupiter, aren't they almost the same size as our moon?

00:22:37
Speaker 2: Yeah? Exactly, we're talking about the relative sizes, and some of the moons around Jupiter are huge, absolutely, and potential places for life to exist, which is one of the things that makes us wonder whether Moon's around exoplanets might also be habitable.

00:22:49
Speaker 1: All right, Well, we talked about how we can see other planets in other stars in the universe, and I guess as as star wars were like, Okay, we've seen those. Now let's increase the difficulty. Exactly, fine, things orbiting not just around other stars, but around the things that are orbiting around other stars.

00:23:05
Speaker 2: And this is the game in science, right. People have come along and done the simplest thing. All right, now, let's come along and do the next harder thing. And then the next generation's like, well that was easy. Now let's do the next harder thing. And so I love how we're always making the progress. We're always pushing the boundaries here.

00:23:19
Speaker 1: But are we done though? I feel like I'm still waiting for that, you know, actual picture of another planet in another solar system, you know, like a like a photograph, photograph.

00:23:28
Speaker 2: Yeah, No, we're never done right. We're always pushing, but we're pushing in lots of directions. Simultaneously, people are working on that photograph. One idea that's being worked, one which we talked about in the podcast, is like using the Sun itself as a gravitational lens. You put a camera out deep in the solar system. You can use the Sun to gather a huge amount of light from a distant solar system, and the Sun will focus all that light on the camera you have out like near Neptune, treating the Sun like this huge lens and making a solar system sized camera that could give you a picture of the surface of exoplanets.

00:24:00
Speaker 1: Wait what like our sun?

00:24:02
Speaker 2: Yeah, our sun. You have the Sun acting like a gravitational lens, gathering light and then focusing it on a camera you put like way deep in the soil system, and you can take a picture of something super far away with a lens effectively the size of the Sun.

00:24:16
Speaker 1: Whoa pretty cool, let's do it, Picker, It didn't happen.

00:24:21
Speaker 2: It's pretty tricky project because you have to get a camera like pretty far out in the solar system and that could take decades, and then moving it takes a long time, but it definitely can be done, and someday we will see the surface of exoplanets.

00:24:33
Speaker 1: And then you got to get the aliens to stay still and smile for the camera, and it takes, you know, a thousand years just to say cheese.

00:24:40
Speaker 2: Yeah. Then they have to sign that waiver, you know, so you can publish the picture.

00:24:45
Speaker 1: There you go. You seem really concerned about the aliens here.

00:24:49
Speaker 2: Hey man, I'm just looking after them. I just don't want them to come and punch us in the face over something silly like legal forms.

00:24:56
Speaker 1: You don't want to punch you in the phase when you take a picture of them in the bathroom, I.

00:25:00
Speaker 2: Have no idea when they're in the bathroom, Like, what are you doing over there? Is that what you call the bathroom? I don't know. I'm just taking pictures.

00:25:06
Speaker 1: I see ignorance.

00:25:08
Speaker 2: Yeah, look, look, I just want to say, there's a lot of moon jokes I'm not.

00:25:11
Speaker 1: Making around here, thankfully, thankfully. All right, Well, then how can we see these ex moons? We basically use the same methods we used to detect other planets, or are we trying some different things?

00:25:22
Speaker 2: Both The bread and butter is to take the same methods and make them super duper sensitive. Like the transit method is one of the most sensitive methods for finding these planets if everything is lined up, and you can also use it to discover the Moon's in a couple of ways, because the moon will affect how the planet blots out the light from the star Number one, it can affect when it happens like the moon is tugging on the planet the same way the planet is tugging on the star, which makes when the planet gets in front of the Sun and blocks its light change a little bit. As the moon is orbiting the planet, it's like yanking on the planet a little bit, So it changes the timing in these transits, right.

00:26:03
Speaker 1: Like I guess, like our moon, the moon here is making the Earth wiggle a little bit. And so the idea is that in another planet, in another solar system, if it has a moon, a big enough moon, it's making that planet wiggle, and so when it moves in front of its star, it's going to block the light in a wiggly fashion exactly.

00:26:20
Speaker 2: And if you count enough of these transits, you can start to notice these patterns, and then you can fit it to a model you can say, like, well, can I explain why this transit was a little bit later and that transit was a little bit earlier. By assuming that there's a moon there pulling on it, is it all consistent? You don't just like look for noise and say, well, I don't know it was noisy, maybe there was a moon. You have a specific description of what that moon might look like and how it would affect the planet.

00:26:45
Speaker 1: Right, Like, if you notice it the wiggling is regular, then you know there's something going on, Like it can't just be like random wiggling exactly.

00:26:52
Speaker 2: And there's a second way, which is that the moon itself can also contribute to blocking the light, not just when the planet blocks it, but the moon could also have its own little moony eclipse, right because if the moon is lined up at the same time as the planet, it can add a little bit of eclipsiness to the planet. It effectively makes the planet's shadow a little bit bigger. And if you have a model for how that moon is orbiting the planet and when the planet is going around the Sun, you can predict exactly when the Moon's going to be in the right position to add to the eclipse.

00:27:22
Speaker 1: But wouldn't it always block the lights in the sun, Like, you know, it's pretty small compared to that planet, and the planet is small compared to the Sun. Wouldn't it always be sort of insight or in view.

00:27:33
Speaker 2: It might always be in view, but it doesn't always have to contribute to the amount of eclipse. Like let's say they're all lined up. If you see like moon and then planet, then star. If the moon is already in the shadow of the planet, then it's not contributing to the decrease in the light. Only when the Moon is sort of offset a little bit from the planet, so it like adds a little shoulder to the planet. Is it going to increase the amount of light that's being blocked? And that's the kind of thing they look for. They look for these trans dips with like a little wiggle on the down edge or a wiggle on the up edge when the moon is peaking around the side of the planet. Basically have to have moon rise or moon set along the planet for it to contribute to the transit dip.

00:28:12
Speaker 1: Wow, but now we're talking about like a super duper tiny dip in the light, right Like our moon would block very little of our giant Sun.

00:28:20
Speaker 2: Yeah, exactly. We're talking about really sensitive measurements, and until recently people allowt this is impossible. You know, you'd need very very accurate understanding of the light and very precise measurements of the intensity of the light coming from these things. So it wasn't until like two thousand and seven, more than a decade after exoplanet discoveries, the people really started working on this in detail, like taking the idea seriously. And one of the biggest challenges is that most of these techniques that we've used to find exoplanets are good at finding planets close to the star, like we talked about hot Jupiter's right, really big planets really close to their stars. But those planets are unlikely to have moons. And though that makes it very challenging to find any of these moons.

00:29:03
Speaker 1: Why are they unlikely to have moons?

00:29:04
Speaker 2: For the same reason that Mercury and Venus don't have moons in our Solar system, right, all the other planets have them, and Mercury and Venus don't. It's because of the tidal forces from the Sun. As you get close to the Sun, the tidal forces, the difference in gravity from one side to the other side of a planet, for example, get very very intense, and that will just disrupt the orbit of a moon. In order to have a moon orbiting a planet, you basically need the Sun to leave it a little bit alone. You need a planet to be able to dominate the gravitational experience of that moon, so the moon can be trapped in an orbit. But if the Sun is really really close by, then the Sun's tidal forces make a moon's orbit impossible.

00:29:43
Speaker 1: Like they'll tend to pull the Moon towards the Sun and then eventually that moon will either fly off into space or fall into the Sun exactly.

00:29:50
Speaker 2: Essentially, it's like a three body system, which we've talked about before, is fundamentally chaotic. The only arrangement for a three body system to be stable is if two of those bodies are pretty close together and pretty far from the third body, which is like, if you have a distant planet with the moon orbiting it, that planet gets too close to the Sun, you now have a three body problem and you're going to lose your moon.

00:30:09
Speaker 1: So you're saying that's kind of a problem because our exoplanet detection methods depend on being close to the Sun. But those planets might not have any moons exactly.

00:30:17
Speaker 2: So the kind of planets we're good at finding are the kind of planets we expect to not have very many moons. On the other hand, there's lots of planets out there, and we can sometimes see planets a little further from their star, and maybe one of those hot jupiters will have a big enough moon that's orbiting close enough to it to be stable. So there's not no hope. But it's pretty tricky.

00:30:38
Speaker 1: But I thought the transit method, the one where we're looking for eclipses and distant stars, those don't depend on the closeness of this planet.

00:30:45
Speaker 2: They do indirectly depend on the closeness of the planet. What you want is a short period, because you want to see many transits. If your planet is really far from your star and orbits like once every eighty years, then you're most ever going to see one transit, And it's pretty hard to be sure that what you're looking at is a planet if you only see one eclipse. If you see it regularly and it happens every four days, and you can really study it in detail, and you can convince yourself that you're seeing a planet, not for example, like a star spot, something on the surface of the star that's dimmer and darker and decreasing the intensity of the light.

00:31:18
Speaker 1: The period of the orbit makes a big difference.

00:31:21
Speaker 2: Yeah, exactly, because you want more examples.

00:31:23
Speaker 1: Right right, Yeah, Like some of the planets in our Solar system take like two hundred years right to go around the.

00:31:28
Speaker 2: Sun exactly, And so if you're an alien graduate student and you're trying to discover Pluto in our Solar system, then you're going to be a student for a long long time.

00:31:36
Speaker 1: Yeah, it's going to take even longer to get that PhD thousands of years.

00:31:42
Speaker 2: I hope you guys live long out there.

00:31:43
Speaker 1: So then what about direct imaging, like taking a direct photograph? Is in that better for planets that are far away from the star.

00:31:50
Speaker 2: Yeah, that's possible. We're sort of just on the cutting edge of being able to do that even for planets, and so we're pushing those limits and we're developing new technologies and this whole new generation of space based telescopes that are gonna be super awesome at doing direct imaging of those planets, and so as that gets better, it'll start to be possible to potentially see moons around those planets. But you know, as we said, like currently planets are basically one or two pixels, so resolving a moon around those planets would be really challenging. With a couple of exceptions, if those moons have ways to like really make themselves known, then we might be able to see them.

00:32:27
Speaker 1: So Like, for example, if you look at Jupiter here in our Solar system with a regular telescope in your backyard, you can actually see the moons of Jupiter, right. You see little points around the bigger circle of the planet. It is that if you point a bit powerful enough telescope and these distant planets, you could see maybe the dot front the planet, but also maybe little dots around it that might be the moons.

00:32:48
Speaker 2: Yeah, you might, especially if those moons are weird in some way, Like if those moons are super volcanic and they're shooting out really hot gases, you might be able to spot that. Or if the moon munds are super duper hot, like they're squeezed by their planet with tidal forces so that internally they're very high temperature, then they might glow at a different temperature than their planet and be easier to see them, and so there's some weird kind of moons that you might be able to direct image before regular normal humps of rock. But I think we're gonna have to wait for our direct imaging technology to improve significantly before we can expect to see pixels from exo moons.

00:33:26
Speaker 1: Interestingly, I wonder if you can like do like the cliffs method on a planet that's far away, you know what I mean, Like if if you're looking at the life from reflected from a planet and you see a dip itself, I wonder if that could be a sign that there's the moon there.

00:33:39
Speaker 2: Yeah, that's a cool idea. And you're right, the reflected life from that planet should dip when the moon passes in front of it. Again, we're still at the cutting edge of even seeing pixels from those planets, and so there you'd need like to study those pixels over time and to look for dips and to understand every other possible source of dips. Because that planet is light, is already going to be variable as the planet goes around the star, So you're gonna have to understand that and then variations on that. But yeah, that's a cool idea.

00:34:08
Speaker 1: Thanks, I'll take the Noble Price. We have it on record. All right, Well, these seem like long shot sort of sounds like from what you're saying that we're not super close to being able to do this. But have we have we found any moons out there and other planets? Have there been any discoveries?

00:34:23
Speaker 2: So we are right on the edge of being able to do this, which means that we have like a couple of candidates that are disputed. There are some people who think these probably are exo moons and other people who think they're probably not. You know, the evidence is like really right on the edge, and people split over the statistical analysis of these things. But it's fun because we have a couple of things to dig into and to talk about.

00:34:44
Speaker 1: All right, let's do it. What are these candidates for possible exomoons?

00:34:48
Speaker 2: So there was one discovered in twenty eighteen. This is the first exo moon candidate, and it's around planet Kepler sixteen twenty five B. Kepler sixteen twenty five is the star, B means the planet, and then the moon is called Kepler sixteen twenty five B. Dash.

00:35:05
Speaker 1: I Well, why I was there an abcd FGH moon or are they're just going for like an iPhone reference here.

00:35:13
Speaker 2: No, I think it's Roman numerals, Like the first one's going to be I, the second one's going to be II, the third one would be III.

00:35:19
Speaker 1: This kind of thing, uh I see, all right, Yeah, switching it up exactly.

00:35:24
Speaker 2: And so here's this two separate, independent pieces of evidence that suggests that there might be a moon here. What we're looking at is a Jupiter size planet around the star right, but it's like earth distance from the Sun, but it's like a huge planet.

00:35:39
Speaker 1: That's what we think is there.

00:35:40
Speaker 2: That's what we think is there. That's the planet that we're pretty sure is there. That's Kepler sixteen twenty five B.

00:35:45
Speaker 1: It's mass, but maybe not necessarily it has to be gas giant, does it.

00:35:50
Speaker 2: We know some of about it's mass because we know it's orbit and so we know roughly its volume, and we know it's roughly it's mass, and so we can tell something about the density. And these planets of this size are almost always gas giants.

00:36:00
Speaker 1: All right. So that's what we think is there.

00:36:03
Speaker 2: And so it's sort of an unusual planet already because it's a cool Jupiter. We talked earlier about how lots of the planets we've discovered are hot Jupiter's big planets very close to their star, like within the orbit of Mercury, you know, but this is farther out orbit makes it a cool Jupiter. And the first thing they noticed is this transit timing variation that the planet is blocking the light from the star behind it. But it's not in a regular fashion. There're wiggles there and exactly the way you would expect if there.

00:36:30
Speaker 1: Was a moon, I see. So it's not like going around its Sun in a regular way. It has a little wiggle to its orbit exactly.

00:36:37
Speaker 2: It has a little wiggle to its orbit, which can be explained very nicely by the presence of a moon. Like they do all the statistical calculations, they have two models like with and without the moon, and the one with the moon better explains the data, like much much better explains the data than the model without the moon.

00:36:54
Speaker 1: Although couldn't it be something else as well?

00:36:56
Speaker 2: It could be something else, right, It could be that there are other planets in this solar system and those planets are tugging on it, and that'd be much more complicated because you could have multiple planets like several Jupiter sized planets that are yanking on it. It's very difficult to model. And that's one reason why this is not a smoking gun discovery, because there are other ways that you could get this kind of signature. What they did follow up is they looked at some Hubble data. They looked at Hubble data pointed at this star to see if they could see an impact of the Moon on the transit itself, not just the timing, but like, could we see wiggles in the dip right? Are there like shoulders in this transit that indicate that we're seeing like a moon rise as the planet is blocking the light from the star.

00:37:39
Speaker 1: Like, is the moon from this cool Jupiter also blocking the light from the star Sometimes.

00:37:44
Speaker 2: Yeah, exactly. And we only have unfortunately, one really clear transit because this comes from Hubble, and Hubble is not a planet finding telescope. It's busy doing lots of things. It's not always looking at one star. So they have only like forty hours of data from this star with Hubble. But they did see a clear transit and there is a dip there that looks like a Neptune size moon around this Jupiter sized planet.

00:38:09
Speaker 1: Whoa that would be a huge moon wouldn't it.

00:38:11
Speaker 2: Yeah, literally, that would be huge.

00:38:14
Speaker 1: More like a sister planet almost.

00:38:15
Speaker 2: Yeah, although technically if it's orbiting a planet, then it's a moon.

00:38:19
Speaker 1: But what if they're both planets.

00:38:20
Speaker 2: Yeah. This gets into a really murky territory of where you define things to be binary planets and where one of them is a moon. They have this definition where if the center of mass is inside the surface of one of them, then one of them is a planet and the other one is a moon. And in this case that Jupiter is so much bigger than the Neptune that the Neptune qualifies as a moon.

00:38:41
Speaker 1: You only have one data point. Why don't we get more?

00:38:44
Speaker 2: I think that people are excited about that and are working on it, But you know, hubble time is very very precious, and there's lots of good things to use hubble for. In the meantime, people have been like analyzing this and reanalyzing this, and other groups have analyzed this data, and not everybody agrees with the interpretation that the first paper came up with. Some people look at the transit data and they say, no, there's no dip there from a moon. It doesn't look like there's any shoulder there. Another group analyzed it and said they do agree with the shoulder, but they disagree with the uncertainties and the other measurements. And the point is that the data is fuzzy, it's not crisp and clear, it's not obvious. It requires like heavy duty statistical techniques to extract this information, and so we just really can't be one hundred percent confident.

00:39:25
Speaker 1: Wow. So they posted this paper with just one data point.

00:39:29
Speaker 2: Well, they have one example of the transit, but they also have the transit timing, right, So those are two independent streams of information. One is the timing of the transits and the other is like the actual photometric like looking at the dip in the light, seeing the moon itself actually eclipse. They have lots more of examples of the Moon tugging on the Jupiter and changing its transits, but only one example of the moon itself blocking the light.

00:39:52
Speaker 1: And they sort of match together. I guess right.

00:39:55
Speaker 2: They do match together according to one group and their analysis, and they don't match together according to another group.

00:40:01
Speaker 1: Sounds like they need more data.

00:40:02
Speaker 2: We definitely need more data. We need more telescopes and more eyeballs. It's so frustrating when our knowledge of the universe is just limited by like how many eyeballs we've built, because there's nothing stopping us from building more. It's just money.

00:40:15
Speaker 1: It's just money.

00:40:16
Speaker 2: It's just money.

00:40:17
Speaker 1: It needs money.

00:40:19
Speaker 2: We can just print more. Come on, let's do it. Print some more money, makes it more scope. Done, Let's do it. Hey, a lot of engineers will be put to work building the Daniel Fund the telescope.

00:40:32
Speaker 1: Yeah, I'm sure, I'm sure.

00:40:34
Speaker 2: Okay, I will print my own money and I'll see if engineers out there will accept it as payment one hundred thousand Daniel bucks.

00:40:40
Speaker 1: Well no, Well, I mean, if you commit fraud that way, who's going to believe your scientific findings?

00:40:46
Speaker 2: Yeah, exactly, And that's why there's no Daniel Space Telescope.

00:40:51
Speaker 1: All right, Well, what's another discovery we made in this attempt to find other moons?

00:40:55
Speaker 2: So there's a second potential discovery. This one's Kepler seventeen oh eight b dash I. And this was a really cool strategy to look specifically for planets that have long periods that are further away from their stars, because they're rarer, at least in our catalog. At least they're rare in the kind of things we can see, but they are more likely to have moons, we.

00:41:16
Speaker 1: Think, because that's kind of the trend in our Solar system, right, Like we have one moon Mars is two in the inner Solar System, but in the outer Solar System, like Jupiter and Saturn have dozens of moons.

00:41:27
Speaker 2: Yeah, exactly, because further you get away from your star, then the more freedom you have to like dominate your gravitational environment, capture moons or retain moons or all that kind of stuff. So they thought, well, let's focus on cool giants, these planets that are further away, and then the whole catalog of exoplanets we've ever discovered, they're only like seventy that qualify is these cool giants.

00:41:49
Speaker 1: I see. If they're not cool, they're not included in the study. You're not invited to the party. Only cool giants.

00:41:56
Speaker 2: Hot giants is a totally different party with a totally different vibe. Yeah.

00:42:01
Speaker 1: Here, it's more of a hipster you know scene.

00:42:03
Speaker 2: Yeah, we're listening to jazz around here, so sit down, have a drink, chill out.

00:42:08
Speaker 1: I'm not sure jazz is considered cool by the kids these days.

00:42:12
Speaker 2: All right, thanks for filling me in, all.

00:42:13
Speaker 1: Right, well, let's dig into this cool giant moon what we know about it and what it tells us about how solar systems form. But first, let's take another quick break or right, we're talking about cool giants, not the you know, plain old giants, not the lame giants, but the cool giants, and seeing if they have any moons in them. That's right, The moons have to be cool too.

00:42:50
Speaker 2: Some of these moons could be hot, right, they could be volcanic, They can have all sorts of stuff going on inside. Even if the planet itself is pretty.

00:42:57
Speaker 1: Cool, that would be cool, all right. So we've been talking about finding moons and other planets outside of our Solar system in distant stars, and there are many different ways to do it that are getting better and better every day. And so we have a couple of candidates of things that might be moons exo moons out there, and one of them is this one called seventeen oh eight b I.

00:43:17
Speaker 2: That's right, and this one was just discovered last year, twenty twenty two. And they looked again at the transits they're looking for like shoulders when this planet is going around the star, are there moments when it's blocking more light than you expect, which could be explained by having a moon orbiting that planet and like rising past the limit of the planet or coming around the back and blocking the light. And so they were looking for these little shoulders, and it's really pretty cool they do see some they see these little shoulders inside this transit lip.

00:43:48
Speaker 1: And I think by shoulder you mean like if the planet didn't have a moon, when it stopped making an eclipse with the star behind it, the light from the star would just drop off, or at least drop off relatively quickly. But if it has a little moon maybe trailing behind it, then the light from the star would go down mostly but not all the way, but then a little bit of a shadow would remain, and then the shadow would go away. And that's the kind of thing you're looking for. Right.

00:44:11
Speaker 2: There's a moment after which the planet is no longer blocking the star, but the moon might be blocking it a tiny little bit all by itself, which extends this transit dip.

00:44:21
Speaker 1: Or maybe the moon isn't like in front of the planet, and so then first the moon gets out of view of the star, and then the planet drops out of the eclipse, and so you see this little shoulder in the light from.

00:44:32
Speaker 2: The star exactly, and so they see this shoulder and they can explain it using again a Neptune size moon. This planet has a Mars like orbit, so it's even further from its star than the previous one. And the planet itself is huge. It's five times the massive Jupiter, so it's a really big planet with a Neptune size moon candidate. And the only explanation we have for these shoulders is an exo moon. There's no other explanation other than like just random noise, you know, maybe it's just fluctuations in the data. And they've done a statistical calculation and that seems unlikely to like one part in one hundred or so, so it's not like smoking gun evidence again, but it's a pretty nice signature of what could be a Neptune sized exo moon.

00:45:17
Speaker 1: And we have more than one data point here in this case.

00:45:19
Speaker 2: Yeah, we have more than one shoulder. They've seen several transits of Kepler seventeen oh eight.

00:45:25
Speaker 1: And it always has this little shoulder, or would you expect it to sometimes have a shoulder sometimes not have its shoulder because the moon is kind of going around the planet.

00:45:33
Speaker 2: Right exactly, So you expect the shoulder to vary, and they see it vary and just this way you would expect for a moon, right, it has the right wiggles at the right time.

00:45:43
Speaker 1: H Like, if you assume this, this moon, this neptum sized moon, is going around every month, and you see it in a monthly way in the orbit of the planet around the start exactly.

00:45:53
Speaker 2: And in this case they're able to calculate the orbit of the moon around the planet and has a period of several days, and so they factor that into their model. They have this mathematical model that says, here's the star, here's the planet, here's the moon going around it. When should we expect to see dips from just the planet, from the planet plus the moon. From just the moon. They can use that to predict very precisely the light curve they expect to see, and it all lines up. I mean in reality, they've done it in reverse. They've said, what mathematical model of that solar system would explain the dips that we see? And the cool thing is that they can't explain it, and they can only explain it with a model that includes a moon.

00:46:31
Speaker 1: Pretty cool. Can they tell how far away. This moon is from its planet, from the shoulders with or the size of the shoulder. That must be how they're estimating that, is its neptune size or is it from how the light dips.

00:46:44
Speaker 2: It's definitely from how the light dips. The period comes from when those dips happen. So yeah, you can estimate the volume of that moon and the period of that moon.

00:46:55
Speaker 1: Cool. Well, was that a big deal when they discover this or is this still something they're confirming this?

00:47:00
Speaker 2: There's definitely something they're confirming. Nobody's like one hundred percent sure that this is an exomoon. It's like in the candidate stage, and they're planning to observe more with Hubble and with James Webb and with other devices. The next transit of this planet in the star was in March of this year, and so I hope that they got some data and they're analyzing it now.

00:47:19
Speaker 1: Yeah, as we speak, it might be confirming this right now.

00:47:23
Speaker 2: And as more data comes in from more cool giants or more exoplanets, we're going to see more and more hints of exo moons, until eventually this goes from like maybe tentative discovery to like we are drowning in exo moons. They're everywhere. You know, people who get their PhD and like a single tentative discovery are going to be amazed when ten years later people are doing their PhDs with thousands of candidates.

00:47:46
Speaker 1: Oh, man, I guess that's how it went with exoplanets, right, Like people for work for a long time just to find one exoplanet, and then as the technology and the techniques got better, and now they're finding them by the thousands.

00:47:57
Speaker 2: Yeah, exactly. Now people are doing like statistical analysis, you know, distributions of planet sizes. They're looking at trends in these planets to try to understand what it means about how solar systems form. And so right now or at this very exciting moment, we're on the cusp of being able to see these exo moons, and we know that as technology improves in the future, we're going to be able to ask and answer really interesting questions like how common is it to have hundreds of moons in a solar system, or to have moons whose relative size is so big compared to the planet like ours is.

00:48:29
Speaker 1: I guess that's the big goal, right, is to compare other solar systems to ours. It's like our most solar system out there like ours, or is ours weird? And if it's weird, why is it weird? Right?

00:48:40
Speaker 2: Yeah? And is that weirdness crucial for life or maybe it hindered life here in our Solar system and made it less likely? Right? Maybe life is really really common in the universe and we relate to get started because we have a weird moon or not enough moons or too many moons or something. What we know is that they're going to be surprises. Like when we started discovering exoplanets, we were surprised by what we found. Our models of how the Solar System formed have been completely upended by our discoveries about exoplanets and exo moons. I'm sure will also have lots of surprises.

00:49:11
Speaker 1: Yeah, Like it was a big surprise how many exoplanets there are out there, right, especially the ones that are like Earth.

00:49:16
Speaker 2: Yeah, exactly how many hot jupiters there were. And the diversity of moons in just our Solar system is crazy, right. We have moons that were formed with planets, we have moons that were captured, moons made had a weird stuff, moons that might have come from collisions. They're probably a whole other ways to make moons we haven't even thought of because they don't exist in our solar system. The diversity of exo moons is going to be really, really wild. There's going to be some weird stuff out there.

00:49:41
Speaker 1: And moons have a big impact on life itself, right, Like think about how much of life on Earth is sort of sync to the lunar calendar.

00:49:48
Speaker 2: Yes, some people speculate that having such a big moon with its dramatic tides could have had a big impact on the formation of life here on Earth. People think that, like in the brackish water between the fresh water and the salt water, that the sloshing around and the mixing up of all those chemicals and the primordial soup might have really helped life form, And so having the moon there with its big dramatic tides could have been a big boost to the formation of life. It might be that it's crucial to have such a big moon. That'd be really fascinating. Right if we found life in other solar systems and in every case they had a weirdly big moon.

00:50:22
Speaker 1: Whoa, we might have the moon to sign for being here.

00:50:26
Speaker 2: Exactly or it might be that mostly life is on moons, right, that maybe moons are a better place to have life than actually the surface of the planet. You know, we think that for example, under the ice in Europa or inside Io or on Ganymede, there might still be life in our solar system. So it might be even in our solar system that it's rare for life to start on a planet compared to moons.

00:50:51
Speaker 1: Yeah, it might be that life is over the moon. About having a moon, and that.

00:50:56
Speaker 2: Joke exactly, and people have really fun about how life can evolve on these moons, using like the planetary magnetic field as a shield from cosmic rays and being close to the star but avoiding being tightly locked to the star. There's all sorts of reasons why life could form on a moon. And because there are so many more moons than planets, we think that means even more places for life to start.

00:51:21
Speaker 1: Right, Right, All the moons harder to have an atmosphere because they're smaller, are.

00:51:26
Speaker 2: Smaller, so it's harder to have an atmosphere. But you could have life within those moons, right, You could have underwater oceans. Most life in the universe might be under ice crusts.

00:51:37
Speaker 1: Whoa, they might be cooler than us, or more most certainly they are cooler than us, at least us here on the podcast.

00:51:44
Speaker 2: They might have no concept of the universe. Right, If you form in a dark ocean, you can't even access the sky, Right, you'd have to somehow drill a hole in that ice and climb out before you even know that the rest of the universe is there. What a crazy mind shift that would happen to be.

00:52:00
Speaker 1: Well, there might be like how we thought about the Earth of the universe before, Right, we thought there was a ceiling. Basically, they might actually have a ceiling.

00:52:07
Speaker 2: They might literally have a ceiling exactly.

00:52:10
Speaker 1: Well, hopefully they'll blow the roof off with that bit of science there.

00:52:14
Speaker 2: We're always in awe of everything we discover and always surprised by what the universe has in store for us.

00:52:19
Speaker 1: Yeah, because I guess scientists are always aiming higher. They're always getting more and more ambitious. In other words, they're always shooting for the moon. All right, Well, we hope you enjoyed that. Thanks for joining us, See you next time.

00:52:40
Speaker 2: Thanks for listening, and remember that Daniel and Jorge explain the universe is a production of iHeartRadio. We're more podcasts from iHeartRadio. Visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.