#19: Making moons in an Italian restaurant
TRABSCRIPT
Corinne Caputo
Welcome to pale blue pod, the astronomy podcast for people who are overwhelmed by the universe but want to be its friend.
Moiya McTier
Oh, that's so cute. Hi, I'm Dr. Moiya McTier. I'm an astrophysicist and a folklorist. And I am a friend to the universe. I got invited to its birthday party next millennium. I can't go I'll be dead.
Corinne Caputo
are they free tonight?
Moiya McTier
Oh, well, you know, we are the universe. So are we free tonight? That's the real question.
Corinne Caputo
I'm going to see my nephew's tonight.
Moiya McTier
Oh, good.
Corinne Caputo
good. And I'm Corinne Caputo.
Moiya McTier
Yeah, Like who are you?
Corinne Caputo
Who am I? Writer, funny person and friend of the universe.
Moiya McTier
Yay.
Corinne Caputo
And I'm so excited about where we are today.
Moiya McTier
Where are they? Yeah,
Corinne Caputo
speaking of my nephew's we are in an Italian restaurant. And I say that because I'm from Staten Island. So there is a extremely cozy aspect to an Italian American restaurant. They all have the same menu and yet they're all completely different. So different.
Moiya McTier
So different. You're right. Yeah, like the sauce. Yeah, I know. I know that the sauce is gonna be different at different restaurant. Yeah.
Corinne Caputo
Yeah, and boy Is it scary when you like, try the red sauce at a new place? Because you're like, what's, what's this gonna be?
Moiya McTier
So this is a restaurant that you grew up going to?
Corinne Caputo
You know, I'm debating whether I say the name because I'm not sure I'm morally aligned with a lot of these.
Moiya McTier
But you but you know this red sauce?
Corinne Caputo
Yes. Yes. And it is cozy and comforting to me. And you know, I would even I just found out they do ship it frozen to your house. So I got it from my birthday last year for my brother. Very cute.
Moiya McTier
Oh, I love that.
Corinne Caputo
I'm gonna have to do that again. Yeah, the famous twin
Moiya McTier
famous twin. Actually, I think we decided that he was the infamous one.
Corinne Caputo
You're right. You're so right, I gotta write that down.
Moiya McTier
Well, I might ask for your advice, your recommendations when it's time to order, but we are. We are here in this corner booth in the restaurant-
Corinne Caputo
thankfully
Moiya McTier
talk about, thankfully, you know where it's a little bit quieter. We don't have to worry about people interrupting us because we're so everyone knows us. And they keep asking us the space questions.
Corinne Caputo
Exactly. And I didn't take us to the other italian restaurant where they randomly like clean a glass and everyone like, you know, kind of lassos a white napkin around their head. I don't know why.
Moiya McTier
Why
Corinne Caputo
I'll have to ask the community about that one because I really don't know why we do that. I guess it's fun.
Moiya McTier
I guess so. Wow. Okay. Yeah. Glad we're not gonna have to be dealing with that while we're talking about today's topic, which is Moon formation.
Corinne Caputo
The moon! I love the moon.
Moiya McTier
how do you feel about other moons besides ours?
Corinne Caputo
I think they can join the club. They can definitely do in the club. I have such an affinity for the moon that I get to see all the time. So obviously that's my favorite moon.
Moiya McTier
Obviously and we have decided that the moon our Moon Earth's moon is for the people.
Yeah,
What's not to love?
Corinne Caputo
Exactly, exactly. It's the I can't think of a single word to describe it. It's so beautiful and I love it.
Moiya McTier
So yeah, in this episode, I want to talk about how scientists think our Moon formed. I want to talk a bit about other moons in the solar system. I want to talk about rings, rings around planets.
Corinne Caputo
Yes.
Moiya McTier
And then eventually I want to talk about the search for moons around planets around other stars. These are called exomoons. Yes, so that's very exciting. And if if you listeners make it to the end of the episode, which I highly recommend, not just this one, but for all of our episodes, to the end-
Corinne Caputo
we reveal a secret at the end of every episode
Moiya McTier
we're going the ally ward route. You know, Corinne I've been thinking about our moon fall review. I've been thinking about the moon fall movie, and if you stay till the end, you will hear my hypothesis for where the extra mass for the moon came from in Moon fall. I think I figured it out.
Corinne Caputo
Okay, I'm glad you said that. Because I also came up with a fun game and Moon fall might make an appearance in it.
Moiya McTier
Oh, good. It's all it's all coming together.
Corinne Caputo
Moon fall is canon to.
Moiya McTier
Fortunately for the movie that got five out of 15 moons. We did not like that movie. But we are going to continue to talk about it.
Corinne Caputo
We should watch it once a year I think and revisit our review.
Moiya McTier
It would be such a sad tradition.
Corinne Caputo
Kind of a curse.
Moiya McTier
You're right.
Corinne Caputo
Also years come up pretty quick. We're gonna be watching it. It's gonna feel like we're watching that movie. all the time
Moiya McTier
No, but like every 50 episodes, it's gonna be another Moonfall review. Oh God hopefully not. So I want to start this with a rundown on planet formation, a review of planet formation. We've talked about this before, but I want to make sure it's fresh in everyone's minds. Although Corinne, can you tell me what you remember? About how planets form? Okay,
Corinne Caputo
Okay, this is really going to show my attention disorder, but So, okay, there are these things that like are orbiting a star?
Moiya McTier
Uh huh.
Corinne Caputo
I'm forgetting the definition of a planet. So a planet? It's like a rock. Right?
Moiya McTier
Okay. Let's start a little bit earlier, where what? How does the star form? What does it come from?
Corinne Caputo
God. No
Moiya McTier
from now on this podcast, when we asked the question at the beginning, how does this space thing work? Corinne says God, and then the episodes over
Corinne Caputo
and then and that's it. And that's really what a podcast should be.
Moiya McTier
Okay, now I'll take you out of the hot seat. And I'll do this review of planet formation processes. So the what we start with is a big cloud of gas. That gas will have different types of molecules in it, there's going to be a lot of hydrogen, there might be some heavier elements that were produced in the cores of now, dead stars. But eventually that cloud of gas is going to cool down, it's going to contract and it will get these little clumps of denser material in it, those clumps will turn into stars. So you have a baby little star in the in the middle, it probably has another stellar companion around it because most stars are born in pairs or in triplets. And around these young stars, you have discs of material of like gas and dust, mostly dust that didn't make it into the star, but still contracted when the gas cloud collapsed. And that disk is called a protoplanetary disk over time as that material orbits around the young star, it will start to collide with other material, other little specks of dust, then you'll have these little pebbles, these little rocks, we call these as they get bigger planetesimals.
Corinne Caputo
Yeah. These are the rocks I'm talking about.
Moiya McTier
Yes, you said, you were right. You are so right. So the planetesimals have sizes of like 10 to like 100 miles across. And eventually those planetesimals will collide to form proto planets, which are almost the size of planets, and then and then you get the planet. Moons can form during that same process, they can form in a disk of debris that forms outside of a newly formed planet. There are a lot of ways that we think moons can form. But for a long time, it was an open debate about how our own moon formed. And now we think we know the answer.
Corinne Caputo
Yeah, it's a mega structure. I believe that.
Moiya McTier
I thought you didn't like that word, Corinne. I thought you didn't want to hear it anymore. And here you are bringing it into this episode
Corinne Caputo
Here I am bringing it up. You just need a little break sometimes.
Moiya McTier
You're right, just a brief reprieve from the megastructures. So I'm not going to give the answer away right now. I actually am going to first tell you a bit about the moon and its properties. And then I'll tell you the different hypotheses that scientists have had. And I'll tell you what we now know about the moon. And then I want you to guess Corinne, which of the processes actually happened?
Corinne Caputo
Okay, okay,
Moiya McTier
we're gonna do a little detective work. And I think we're gonna have a good time. But here are some things that we know about the moon, as we can see it and observe it from our little pale blue dot, the moon is roughly a quarter of the size of the Earth. And please know that there's, for me a very important distinction between size and mass. When I say size, I'm talking about like, the the length of it, the diameter of it. So it has roughly one quarter of the diameter of Earth, which makes it proportionally compared to the planet that orbits the biggest moon in the solar system. There are other moons that are bigger than our moon, but compared to the size of their planets, they are much smaller. So scientists saw this and they're like, what's up? Why is our moon so big compared to the earth, even though it's a quarter of the size of the Earth, it's only about 1% the mass of the Earth, so it is, on average, much less dense than our planet. And gravity on the moon is lower. It's about 1/6 The strength of gravity here on Earth.
Corinne Caputo
I want to jump on that. I want to see, like,
Moiya McTier
Have you seen those videos of the astronauts falling guessing? Oh, I was gonna say like, bouncing
Corinne Caputo
around. When they make a fool of themselves.
Moiya McTier
They're always doing that. No, it's like there's there's the normal video of them bouncing around the moon because it's hard to walk. Michael Jackson's version of the moonwalk so inaccurate. But it is really hard to walk on the moon because of the low gravity so you end up bouncing from place to place and someone some comedic genius, took that video of the astronauts bouncing sped it up and put it to like funny music. Like they're just hopping around.
Corinne Caputo
I'm dying to see this though.
Moiya McTier
Okay, I'll, you can look it up, or I'll give it to you later. But you do need to see this video. So gravity is weaker on the moon, the moon is about 250,000 miles away from us, it doesn't have a perfectly circular orbit. So that's an average. And remember, as we've said before, the moon is moving away from us about an inch and a half every single year. So that is just an average, you could fit about 30 Earths between Earth and the Moon.
Wow
or you may have heard that you can fit all of the planets between the Earth and the Moon and it would be a tight squeeze. You would have to get rid of Saturn's rings. But like you could line the planets up between Earth and the Moon.
Corinne Caputo
Whoa.
Moiya McTier
Yeah,
Corinne Caputo
But then we wouldn't be able to see the moon anymore.
Moiya McTier
Yes. That that would be the consequences.
Corinne Caputo
That is the only reason we're not doing it right now.
Moiya McTier
Oh my god, the moon fall did get the concept of tidal interactions between the Earth and the Moon Correct. I can't- the gravitational disruption from having all events very aligned.
Corinne Caputo
That's very scary
Moiya McTier
So scary.
Corinne Caputo
I don't like that at all.
Moiya McTier
I imagine that would tear Earth apart. If we actually took the planets and put them between us.
Corinne Caputo
Well I'm out. I'm out before I find out but good luck to everyone else. Just.
Moiya McTier
Luckily, that's just not gonna happen. You know this is a fun thought experiment. physically impossible
Corinne Caputo
Nothing to worry about
Moiya McTier
nothing to worry about. The moon, one of my favorite facts about the moon whenever people asked me hey, Moiya, you're an astronomer, do you have any fun facts about space? One of my go tos is that the moon is tidally locked to the earth? Do have you heard the term tidally locked before?
Corinne Caputo
I don't think so.
Moiya McTier
Oh, this is this is really fun. It doesn't just happen to moons. It can also happen to planets and their stars. But basically, when the moon is tidally locked to us, it means that one side of the Moon is always facing us.
Corinne Caputo
that I do know.
Moiya McTier
Yes,
Corinne Caputo
yeah,
Moiya McTier
yeah. So there is a near side of the moon, there is a far side of the moon, there is no Dark Side of the Moon. Another another thing that people usually get wrong about the moon being tidally locked is that they think that means the moon doesn't rotate. That's false. Remember, we've talked before about the difference between rotation and revolution. Rotation is spinning on an axis revolution is orbiting around the central point, the moon revolves around us the earth and that the length of that revolution is the same as the length of its rotation. So like a day on the moon, as it spins is the same length as a month as the moon goes around there.
Corinne Caputo
Oh, wow. Okay.
Moiya McTier
And that's just like, early on. After the Moon formed, it was much closer to the earth so it was experiencing more of a gravitational pull to Earth. And tidal locking happens when you have these extreme gravitational environments and it is like an energetically a favorable state for the moon to be in, for it to be locked in resonance with the earth in this way. So it's just like how how the energy balanced out early on.
Corinne Caputo
Cool.
Moiya McTier
We think Mercury might be tidally locked to the sun, maybe Pluto and its moon Charon, are tidally locked to each other. So you know, like the moon sees all the faces of Earth, even though we only see one of its faces. But Pluto and charon, they're just the same
Corinne Caputo
They're facing each other the whole time?
Moiya McTier
facing each other the whole time.
Corinne Caputo
It feels like kind of like a battle with somebody where you're like, I'm not going to turn my back to you. Like you just kind of rotate.
Moiya McTier
Oh, yeah. That's one way to look at it. I thought that they were like kissing.
Corinne Caputo
Yeah, you're definitely thinking of it in a much happier way than I am.
Moiya McTier
I am. You're right.
Corinne Caputo
Like why? What are the reasons I would never put my back to someone?
Moiya McTier
obviously, we're having a battle.
Corinne Caputo
Yeah.
Moiya McTier
The moon has a small but solid iron core and some liquid layers around that. So it has a core it has a mantle and then it has a very thin crust. And this is something that I did not know before today, Corinne so I'm I'm learning right with you for this podcast. on the near side of the moon, the crust is about 45 miles thick, which is pretty thin. It's much thinner than the crust on Earth. But on the other side, on the far side of the moon, the crust is much thicker, it's like almost twice as thick, like 90 miles. And that is because the far side of the moon, since it wasn't facing Earth after the Moon formed wasn't experiencing the heat from the very young molten Earth. So it was allowed to cool quicker and solidify faster. And and now it's thicker.
Corinne Caputo
Whoa.
Moiya McTier
And this has a bunch of cool consequences. Like you'll see a lot more craters on the far side of the Moon than on the near side of the moon, in part because it's facing away from us. So the it's easier for things to hit that side. But also because the crust is thicker over there. The volcanic activity that the moon used to have wasn't as effective at filling in the impact craters. on the near side of the moon, the volcanic activity was easily able to fill in the impact craters. So it smoothed out the near side.
Corinne Caputo
Oh, cool.
Moiya McTier
Let's see. Yeah, so I talked about volcanoes, the moon used to have active volcanism it doesn't anymore. And we think that that stopped in the last like 100 million years or so. And temperatures on the moon as it passes in and out of the sun can range anywhere from minus 280 degrees Fahrenheit, up to 260 degrees Fahrenheit in direct sunlight.
Corinne Caputo
That is very cold and very hot.
Moiya McTier
Yes, it has these extreme temperature swings, in part because it doesn't have an atmosphere or much of an atmosphere to help it regulate and distribute heat across the surface. Those are some things we know about the moon.
Corinne Caputo
Ah, I love the moon. And I continue to love the moon.
Moiya McTier
yay, the moon for the people. Alright, so now I'll tell you the different hypotheses people had for how the Moon formed.
Corinne Caputo
Yes.
Moiya McTier
These hypotheses would come they came out in the last century, like over the course of the 20th century. And these are the serious hypotheses there were some that were pretty ridiculous. But the first of the serious hypotheses is called the fission hypothesis. Fission is the opposite of fusion. So fusion is when things come together. Fission is when things pull apart. And essentially the fission hypothesis says that early on in Earth's formation when it was, you know, still a bunch of planetesimals colliding in the sun's protoplanetary disk. It was very hot, it was molten, like all of those collisions, all of those impacts, it increases the temperature, so you had like molten rock forming this sphere that would eventually become earth. And the fission hypothesis says that while the earth was still molten, for some reason, maybe it was spinning too quickly. a blob of that molten Earth separated from the earth and became the moon.
Corinne Caputo
Okay, yep. I don't know about that one. But I that is making me think of a lava lamp again.
Moiya McTier
Yes,
Corinne Caputo
where It just kind of, well, this is so embarrassing that I put on a lava lamp video the other day, just sitting on my couch watching the lava lamp for you know, way less time that video is like nine hours and I watched like two minutes. But there was it was really fun to watch when the little pieces would break off of the big piece. This is how I tried to relax.
Moiya McTier
That's nice. For two min.
Corinne Caputo
I don't think it worked. It didn't. Exactly I gave up immediately. I'm like, you know is boring.
Moiya McTier
it so efficient hypothesis otherwise known as that thing that lava lamps sometimes was one of the hypotheses. The next one was the capture hypothesis. And this said that the Earth formed from that same process of colliding planetesimals. And the moon also formed separately in a different part of the solar system, maybe nearby through this collection of even smaller rocks and pebbles. And then because the Earth had a stronger gravitational field as a much more massive bodies, and so it was a planet and not a moon. Just snatched the moon right up, you know, the moon was passing by, and the Earth's gravity just yanked it. Like you're mine now. I'm gonna hold on to you forever.
Corinne Caputo
I feel like if that were true, wouldn't we have a lot more moons
Moiya McTier
may have?
Corinne Caputo
I'm like, if we're that sticky? There would be more.
Moiya McTier
It's a sticky hypothesis.
Corinne Caputo
Yeah.
Moiya McTier
I like that you're already in Detective mode.
Corinne Caputo
Yeah,
Moiya McTier
Thinking about which, which of these fits with your understanding of how the solar system works,
Corinne Caputo
the listeners can't see. But I've asked the waitress for a magnifying glass and I'm holding it up
Moiya McTier
you are, but just to the air, you're not actually looking at anything. Oh, we're inside Corinne?
Corinne Caputo
Well, you know,
Moiya McTier
you know,
Corinne Caputo
general direction.
Moiya McTier
Yeah, it's still working. It's doing something for you. The next hypothesis was the co creation hypothesis, or the co-formation hypothesis, which says that the Earth formed from that same process, and the Moon formed by a very similar process of smaller things colliding. But they just happened to happen right next to each other.
Corinne Caputo
hmmm
Moiya McTier
They just formed at the same time right next to each other.
Yeah, I'm not really one for coincidences. Or maybe I am, I don't know, depends on my mood. But that feels like, I don't know, the universe is so big that those random things are going to happen at some point.
Right? Right. They are going to happen at some point, that's for sure. And we're not talking about like the whole universe, we're talking about the solar system, which is a much more local region. So it's more probable that this could happen on these scales. And then the fourth hypothesis that people gave serious consideration to was the giant impact hypothesis, which says that sometime while the earth was not quite molten, but still very young, another object about the size of Mars impacted the Earth, so it hit the Earth and knocked off. Well, the whole earth would have been like moltenized, it would have combined with this Mars sized object, and then a chunk would have been knocked off and the moon would have formed from that chunk. Some people say that first, the stuff that was knocked off in the collision would form a disk or a ring around the earth and then the moon formed from that ring. Others say that, no, it just like it came off and it formed the spherical moon in one fell swoop. Yes. Those are the those are the four those are the four hypotheses Interesting, huh? Are you leaning towards any one over the other?
Corinne Caputo
Okay, so with the Giant Impact theory,
Moiya McTier
hypothesis,
Corinne Caputo
hypothesis hypothesis,
Moiya McTier
there's a difference.
Corinne Caputo
It's the earth is like softer, molten, like, I guess more malleable in that way. Like, we wouldn't still it wouldn't have left like a hole or like a crater or whatever. Okay. So I can't use that as a clue.
Moiya McTier
No, although people in the past who considered this hypothesis believed that there was this big crater in the Pacific Ocean that they said was the spot on the spot. But but you know, like, now scientists looking at the Giant Impact theory have decided that it would have been so powerful to as basically melt the planet.
Corinne Caputo
Yeah, I think it's co creation.
Moiya McTier
Ooh, oh,
Corinne Caputo
It's my gut. Okay.
Moiya McTier
I love that. Why?
Corinne Caputo
I don't know. I think I want it to be giant impact because I like that. The kind of storyline of maybe it's like the reformed Catholic and me who's like with the rib of Adam, we formed the moon
Moiya McTier
You're right. Oh, the moon is just the eve to Adam
Corinne Caputo
get that I do think of the moon as me and extension of me. I do think I come from the moon. Yes. So I think that's what I want it to be from like a fantasy story telling side but I don't think that's what happened.
Moiya McTier
All right Okay. Well, now I'm going to share with you the information we have about the moon that we learned after these hypotheses were come up with
Corinne Caputo
Okay,
Moiya McTier
so like we knew this information Starting after we went to the moon in 1969, so that that 1969 Apollo 11 mission that put humans on the Moon for the first time, also let them bring samples back. So we could study the actual moon rocks and the composition of them and like the molecular and chemical makeup of these moon rocks for the first time. So the Apollo astronauts, they brought moon rocks back, and we noticed two things. One was that the chemical composition of these moon rocks was extremely similar to the chemical composition of Earth rocks,
Corinne Caputo
ooh.
Moiya McTier
Mhm. Now, we are all in one solar system. So we all have the stuff that like goes into our sun. But you still see different chemical compositions in planets at different distances from the Sun. So like, the chemical composition of Mars is different than the chemical composition of Venus is going to be different than the chemical composition of Pluto. Because you find different elements and different molecules at different distances from the Sun. So knowing that the chemical composition of the moon is very similar to that of the Earth. Do you would you like to eliminate any of these hypotheses?
Corinne Caputo
Hmmm Well, I can eliminate capture.
Moiya McTier
Yeah, you can. You want to walk us through that logic.
Corinne Caputo
So capture like I said, like the stickiness of like this thing formed nearby and then got caught in our gravitational pull, but wouldn't have happened if we're kind of made of the same stuff. Well, I guess cocreation to
Moiya McTier
that does make it tricky.
Corinne Caputo
Yeah.
Moiya McTier
But it's still I'd say it like it knocks it down a peg, but not totally out of the running
Corinne Caputo
Yeah, it's not a strikethrough. Yet, or maybe ever. We'll see.
Moiya McTier
Yeah, so that's one piece of information. The other piece of information that we now had, when the Apollo astronauts came back, said that there were fewer, and I'm using air quotes here, volatile compounds in the moon rock samples than you find in earth. And these volatile compounds are elements like potassium and zinc and sodium that we usually expect to see as solids, but they can be vaporized at extremely high temperatures, the type of temperatures that you can achieve during extremely energetic collisions. And so it's expected that the moon maybe had these compounds at one point, but that they were vaporized when the temperature got really high. So does that does that make you think of any other, eliminate any other and
Corinne Caputo
that makes me think of fission? Because I imagine it was very hot when that.
Moiya McTier
But the thing is, the fission hypothesis says that the moon was just this blob that came off of the already molten Earth. So it would have experienced the high temperature at the same time
Corinne Caputo
right. So I guess I can cancel fission out,
Moiya McTier
you can cancel fission. What does this tell you about cocreation?
Corinne Caputo
I don't know that it might be true.
Moiya McTier
Well, so this volatile compound thing essentially tells you that the surface of the Moon was baked, right? That either like while or after it formed, there were a lot of very high temperatures. Do you think that that would have happened during the coformation process?
Corinne Caputo
I don't know. I feel like my gut does not does not work in space, if that makes sense.
Moiya McTier
You haven't developed your intuition yet.
Corinne Caputo
Yeah.
Moiya McTier
Yeah. So the the coformation mechanism wouldn't have the same effect of burning off these volatile compounds because the Earth and the Moon would have formed without any giant impacts.
Corinne Caputo
Okay. Okay.
Moiya McTier
So they would have they would have formed through their small collisions, but then they would have been able to cool down and both of them would have had similar levels of these volatile compounds. So what we learned by studying the moon rocks was that the Earth basically the moon underwent an extra baking process that the Earth did not undergo
Corinne Caputo
interesting. You got to put it back in the oven for a few more minutes.
Moiya McTier
Yeah exactly. The earth is underbaked
Corinne Caputo
Yeah, the earth a little underbaked.
Moiya McTier
as they would say on the Great British Bake Off you know, the Earth has a soggy bottom should have left it in the oven just a few more minutes. Or maybe the moon is just overbaked I don't know what consistency we're going for here.
Corinne Caputo
Yeah, maybe we overdid it on the moon.
Moiya McTier
So that does leave just one of these hypotheses. And that is the giant impact
Corinne Caputo
That is giant impact the one that I liked the most.
Moiya McTier
I liked that you liked it the most but you thought that the real answer was a different one that makes me so happy now you know that the one you liked is what scientists are finding.
Corinne Caputo
I love that. Yeah.
Moiya McTier
Hello It's me Dr. Moiya here to give a shout out to our patrons who are supporting pale blue pod and keeping it going. It really means so much to me to Corinne and to everyone who helps make this show over a multitude. So thank you as always to our sunlike stars Sean Llewellyn Finn, Ian Williams and Meghan moon, you're all just the best thank you so much. And thank you to our latest pre main sequence stars young coconut and active galactic Ra. Oh my god, it's like you were meant to be a supporter of this podcast with that name. I am so thrilled to say that we've finally reached our first goal of having 50 patrons so three of them have been randomly selected thanks to pythons random number generator to receive a free signed copy of my book, The Milky Way and Autobiography of our galaxy. So congratulations to Ileana lado, Jessica Elise and Emma Farrell. You all have messages in your inbox from me just let me know where to send the book and you will have a copy in your hand soon. You can support us here your name on this pod and make it to our patrons star chart all by supporting us on Patreon for just about $1 An episode. You can find all of this info on our website pale blue pod.com Or just go straight to the source and join our community@patreon.com slash pale blue pod.
Corinne Caputo
Okay, if you're loving pale blue pod and especially if you're loving Dr. Moiya McTier. You must give her other podcast XO Laura Ellison. And if you didn't know Moiya is also a folklorist. So if you've wondered about what life would be like on different planets, or how writers create your favorite fictional worlds, Moiya has the facts for you. On exo lore, Dr. Moiya McTier explores fictional worlds by building them with a panel of expert guests, interviewing professional world builders and reviewing the merits of worlds that have already been built. You'll learn You'll laugh, and you'll get an appreciation for how special our planet Earth really is. So subscribe today by searching XO lore and your podcast app or by going to xo lore pod.com.
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Moiya McTier
so that Mars sized object that would have hit Earth early in its formation, scientists have called it theia T H E IA. And that's Yeah, that's probably what happened. I read a paper earlier and it will be in this episode's research notes that like tries to answer the question of did theIA and this impact create a ring around the earth that then coalesced into the moon? Or was the moon produced just like immediately after that impact? This has been an open question because understanding that the Moon formed because of a giant impact still left some mystery about the moon's tilted orbit. The plane of the Moon's orbit is about five degrees off of Earth's orbital plane, which is a little weird, and it didn't super answer questions about the moon's thin crust. So this paper that I found, had a pretty sensational title. But it was these scientists saying that the ring thing probably didn't happen. The moon probably formed right after this impact. They said that it could have happened within like hours, which would be
Corinne Caputo
Whoa, that's so fast.
Moiya McTier
So fast in space like
Corinne Caputo
that, especially don't really happen when things are like billion years down the road. Yes.
Moiya McTier
So they they did some very impressive and high computationally powered simulations of lots of particles that would have been moving around during that giant impact. And what they came up with was that if you have the moon just forming very quickly after the impact, then it explains the tilt of its orbital plane. It explains this thin crust. It also explains why you have a thin crust on one side and a thick crust on the other because these these processes happen so quickly. as it cooled down so quickly that you have these, I want to say and I saw and and I saw trapeze but which is just like jargon for it looks different on my scientist jargon training came back and just took hold over my body and I couldn't think of any other words here
Corinne Caputo
I saw that your eyes rolled back.
Moiya McTier
Oh, what are what is English? That's our moon. That's how our Moon formed. But there are dozens there are over 100 moons in our solar system that we have found. And some of them may have formed through a giant impact. Many of them probably formed through co creation, many of them also could have formed through capture. So it's impossible to know without going to those moons and studying their surfaces and like their rocks and also studying the planets that they orbit. But there is a pretty beautiful diversity of planet formation processes represented in our solar system.
Corinne Caputo
Oh, I really like
Moiya McTier
do you know, true or false? every planet in our solar system has at least one moon.
Corinne Caputo
False.
Moiya McTier
That is false. Yes, Mercury and Venus don't have any moons. And that's likely because the sun's gravity since they're the closest to the sun, yanked some of their moons away or like just didn't let them form moons in the first place. It could also be because of some photo evaporation, which is when you have extremely high temperatures and a lot of radiation that like destroys small particles so that they can't gather together. You do know that the big planets in the outer solar system have like a shit ton of moons, right?
Corinne Caputo
A tons of moons!
Moiya McTier
I do know that so many moons and I think we just found like a dozen more moons around one of the Jovian planets, like we just discovered 12 New Uranus moons or something. It's we're finding new moons all the time. But giant planets, at least in our solar system, and we're still studying to see if this holds true and other stellar systems. giant planets have dozens of moons. And that's mostly because they're strong gravity makes it really easy to hold on to the moons that have formed through any of these processes. It also makes it easier to capture moons that form elsewhere. So they're greedy. The giant planets, their moon greedy,
Corinne Caputo
they're sticky. Yes,
Moiya McTier
Yes. rings.
Corinne Caputo
Rings
Moiya McTier
Earth doesn't have rings, but other planets in the solar system like Saturn and Uranus. They have rings, it's expected that Mars in the future might have rings and that it might have had rings in the past too. Is that is that news to you? Like that was that was surprising to me that I didn't
Corinne Caputo
That I did know because Mars was like a big part of the space center stuff we did. So I have more of a bigger working knowledge of Mars. Oh, also, I did like a Mars themed summer camp. I forgot not through the Space Center. through this other tech company. So yeah, I have a much greater knowledge of Mars than I do of, of anything else.
Moiya McTier
Interesting.
Corinne Caputo
But like more more than like the rover. Yeah, like more in the rover aspect.
Moiya McTier
Maybe we can do an episode where you teach me about the Mars Rovers.
Corinne Caputo
Oh my gosh, I should I had so many little slides from my camp days.
Moiya McTier
Let's do that. I love a slide. Yeah, so there are multiple planets in our solar system that have rings, these rings usually form. Well, they can form just by a planet, accreting lots of small pebbles, things that aren't even planetesimals size. And if it gathers through gravity, Enough small pebbles, then they will start to orbit and eventually they will fill out all the space and it will become a ring. But you can also form these rings around planets by tearing apart other things like moons, which means that out in space, there is this beautiful cycle of making moons and destroying them through gravity so that you make a ring and then out of that ring. Moons form because the stuff in the ring collides. So there's just this happen over and over again. And scientists think that that might be what's happening with Mars's moon, Phobos. They say that in the next 50 million years or so Mars could rip Phobos apart through gravitational interactions through tidal interactions very similar to what they talked about in moon fall. And that a ring would form from that. But they looked into the history of Phobos and we still need to send stuff to Phobos to like study its composition. But there's Yeah, this might be one instance of that cycle of making a moon and then destroying it to make rings and then putting it together to make a move back and forth, which is beautiful. Saturn's rings are mostly ice, which does not necessarily mean water ice. There. It's ice of other elements like methane and ethane ice. And they likely formed in the last 100 million years. Scientists for a while thought that Saturn's rings were quite old. But then once we sent the the Cassini spacecraft to study the the rings and the individual ice particles that make them up, we saw that they're a lot brighter than we would expect if they were old, old things in space undergo a weathering process that will turn them darker you know this happens with the with the moon often and essentially they realize that Saturn's rings are too bright to be old. They haven't undergone much weathering so in the last 100 million years or so, and that ring material is being pulled in by Saturn's gravity so it moves Saturn might eat its own rings.
Corinne Caputo
Yeah, so what would that what would happen if that's happening like he gets closer and closer to this atmosphere and surface of Saturn?
Moiya McTier
Yeah, just gets absorbed in. But Saturn does have a moon called Enceladus. That is sending out geysers of like water and other icy particles. So it's kind of replenishing at least one of Saturn's rings
Corinne Caputo
drama,
Moiya McTier
I know right. Love that interplay. And this has all been in our solar system, the rings and moons in our solar system. But we can also start thinking about moons around exoplanets and rings around exoplanets. My advisor in grad school, his name is David kipping. His name is David kipping. He's not dead. He just got a cat. He had a reputation in astronomy as being the guy who works on kind of, I'm not gonna say wacky, because they're all very, like reasonable. But he had a reputation for pursuing projects. That seemed like they wouldn't be doable for a very long time. Because he, he was one of the pioneers in the search for exomoons the moons around other planets. He started doing this work in like 2006, 2007, I think was the first time he published a paper on exomoons. And they still have not found an exomoon.
Corinne Caputo
Whoa,
Moiya McTier
there is no confirmed exomoon that scientists have discovered they have candidates and he and another grad student in my program, he was a grad student at the time, Alex Teachey, he's now a postdoc in Taiwan.
Corinne Caputo
He did. astronaut training runs my show.
Moiya McTier
Yes, he did
Corinne Caputo
he did with you on the first ever one, maybe probably maybe. That's, that's I know, I follow Alex on Twitter. And it's definitely because he did my show.
Moiya McTier
So David, and Alex found the first exomoon candidate, Kepler 1625 B, which is the planet orbiting Kepler 1625, the Star, and then that planet would have a moon around it, they think. But it's really hard. It's hard enough to find planets around stars, it is nearly impossible to find moons around those planets around other stars. And so one of the most common ways to search for exomoons is to look at the transits. The transit light curves of planets as they orbit their stars. And we're going to talk more about this in next week's episode when we talk about the detection methods for exoplanets. But essentially, you are measuring the amount of light you get from a system, if a planet passes in front of a star, it will block that so if you're graphing the light over time, you see a dip in the light curve. And if there is a moon around one of those planets, and it's orbiting the planet, as the planet orbits the star, then every like you would see the tiny little trace of that in the signal, it could be that as the planet is just starting to pass in front of the star like it's coming over, it's, we call it the the limb or the outer edge of the star. If the moon is going around it, the moon at some point will be in front of the planet. So it will, it will pass in front of the star first. And so you get this tiny little dip, and then the moon goes behind the planet. So the dip goes away, and then the planet goes in front of the star. So you get the bigger dip. So they can study that that little double dip feature and like curve to look for moons, they can also study these two different phenomena. One is called a transit timing variation. The other is called a transit duration variation, or TTVs and TDVs is it's a lot easier to read than it is to say,
Corinne Caputo
I'm seeing notes and I'm like That's a tongue twister for sure.
Moiya McTier
But both of these just look at they're based on the premise that the moon would tug a little bit on the planet just like planets can tug on stars. We talked about that in the redshift episode with radial velocity. And so they if they're really precise about measuring when a planet transit starts in stops and how long the transit lasts. And there's any sort of deviation from what they expect. That's a sign that something is tugging on the planet, like a massive moon.
Corinne Caputo
Cool.
Moiya McTier
So like I said, we've found a few candidates for exomoons. But none of them have been confirmed. Although I like to think that we're going to find one soon. And also we know they have to be out there.
Corinne Caputo
Yeah.
Moiya McTier
Because the the physics of our solar system is it's not special.
Corinne Caputo
Yes.
Moiya McTier
Same elsewhere. So we would expect that if we see moons in our solar system, other planets have them too.
Corinne Caputo
Yeah, I think so too
Moiya McTier
it's just a matter of powerful enough telescopes.
Corinne Caputo
There's so many in our solar system that it it's hard to imagine, it's impossible that there wouldn't be things anymore.
Moiya McTier
So that's all I have on on moons and rings and exomoons. Do you have any questions or thoughts? Before we move on to moon fall?
Corinne Caputo
Well, um, I'm die, I'm sure you'll keep me updated for the rest of our lives. But if we find out where the moon definitely came from, I got you know,
Moiya McTier
okay. Yeah, we are pretty sure the the giant impact hypothesis has kind of turned into the Giant Impact theory. It is definitely the most accepted explanation. So, so moon full moon, definitely go back if you haven't, and listen to our episode, where we review Moon fall. But if you have already listened to it, then you'll remember that one of our big Peeves with this movie was the fact that they kept talking about extra mass. The moon all of a sudden had more mass than we thought it did. There's this scene where KCHausman-
Corinne Caputo
yeah,
Moiya McTier
is talking to people at NASA, about the impending Moon fall. And he says, we're dealing with a mega structure here. So your your rules of gravity don't apply anymore. And I was so mad at that line. But I think that as I've noodled over it since and as I've tried to be extremely generous and open minded, I think I know what KC was trying to say.
Corinne Caputo
What?
Moiya McTier
So if the moon were a natural satellite, if it was just a rock that that formed in space, then we would be able to measure its mass based on its orbit around the Earth. That's just math. But if it's a mega structure, and we did see that it's capable of maneuvering itself, because as soon as the main characters, like, take the bad aliens out of the mega structure, moon, the moon tries to go back to its normal orbit, which means that since it's a mega structure and not a natural satellite, it can I don't know us like thrusters or whatever, to put itself in whatever orbit it decides to be in.
Corinne Caputo
Yes,
Moiya McTier
which means that its mass doesn't determine where it orbits.
Corinne Caputo
Yeah.
Moiya McTier
So I think that what KC was saying is, this is a mega structure, it can move on its own, which means your rules of gravity and the way that you have determined its mass. They don't apply anymore, because the moon can move.
Corinne Caputo
I love that you're thinking of this. I think you're giving them a lot of credit.
Moiya McTier
I'm trying, I like to be kind. Yeah, people who I know put a lot of effort
Corinne Caputo
to come in with like, this is what I hated and was like, here's some things that were great.
Moiya McTier
I did have a lot of themes for me. Yeah, definitely more peeves, but yeah, I just, it's, it's been bugging me. Yeah. Because I know one of the science advisors who worked on that movie, Megan McKinnon is a geo physicist and a disaster researcher. She's consulted with shows like Stargate on their science. And I, I just know that she's so smart. I didn't think that she would let them get away with that.
Corinne Caputo
Yeah.
Moiya McTier
So it's really been bothering me. And I needed to share this view
Corinne Caputo
to prove it.
Moiya McTier
Yeah.
Corinne Caputo
Also, that movie is so funny, because I would bet that any science advisor could come in, and they'd still be like, well, this works for the plot. So we're gonna keep it.
Moiya McTier
Oh, yeah, that is the curse of the science advisor, you can advise, but they don't have to listen to you
Corinne Caputo
No.
Moiya McTier
And I figured, you know, like, maybe it was one of those situations where mica was like, no, no, you can't just wave the rules of gravity. And then the directors are like, Well, screw you. It works for the story. But no, I think I think that this might be what they were trying to do.
Corinne Caputo
I think you did solve it.
Moiya McTier
Thank you. And I'm glad you did. That's where the extra mask.
Corinne Caputo
Okay, well, speaking of moonfall,
Moiya McTier
Okay, I'm ready.
Corinne Caputo
I have a little fun game for us, which is I have a series of quotes in front of me that I'm going to read to you. Some of them are real quotes that were set on the moon, and some of them are not
Moiya McTier
On the actual moon.
Corinne Caputo
Yes.
Moiya McTier
from real life, not from the film
Corinne Caputo
In real life, not in fiction, and some of them are not. So Moiya I want you to use your detective skills, and you can use my magnifying glass if you need.
Moiya McTier
Okay, thank you.
Corinne Caputo
I guess if this was something that was actually said on the moon, or if it wasn't
Moiya McTier
all right, I'm ready.
Corinne Caputo
Okay, here's the first one, quote, the surface is fine and powdery. I can pick it up loosely with my toe
Moiya McTier
with your toe. No astronaut has ever been on the moon with their toes out. They were really heavy boots. So I'm gonna say that's false
Corinne Caputo
It is real!
Moiya McTier
Out here using their toes like they're on a beach.
Corinne Caputo
That is from Neil Armstrong from the Apollo 11 transcripts, which I did Google for this game.
Moiya McTier
Wow.
Corinne Caputo
And are out there. And you know what? They're not that fun. I'm trying to get gossip or something. And it's just like science science science
Moiya McTier
Yeah, they knew they were being recorded. They weren't saying anything juicy. No, no,
Corinne Caputo
No, no, no. Okay. Here's another one. Quote, I can see my house from here.
Moiya McTier
They can't see their house. No, that's false. That's false
Corinne Caputo
That is false. That was from chat. GPT. I asked the A.I. copywriting software to tell me what an astronaut would say on the moon. And that's what he came up with. So I'm out of a job.
Moiya McTier
Yeah. Oh, I have a lot of strong feelings about Chat GPT. Let's move on
Corinne Caputo
Okay, next, quote. It has a stark beauty all its own. It's like much of the high desert of the United States.
Moiya McTier
Oh, I feel like you might be tricking me again. But that sounds totally plausible. So I'm gonna say true
Corinne Caputo
It is. that's also near Neil Armstrong. From the transcripts.
Moiya McTier
Oh, is no one else talking?
Corinne Caputo
Yeah. You know, really? No, because there's even a part of the transcript when President Nixon calls them and it's like, this is the most historic phone call of all time. And I think just Neil spoke back to him. It was just like, one of the astronauts spoke and they were both like on the call, and I was like, you both can talk. I mean, calls whatever.
Moiya McTier
I guess maybe, maybe buzz was a man of few words.
Corinne Caputo
Yeah, I would bet. Okay, next quote. I think you're gonna know this one. Quote, you're telling me that the moon was effectively the biggest cover up in human history.
Moiya McTier
From moon when you didn't want to use the one about the moon being full of produce?
Corinne Caputo
I almost did. I almost did. But I was like, that one's like so obviously Moon fall. Yeah.
Moiya McTier
Okay, what a gem.
Corinne Caputo
Next one? I don't know, lad. It's like no cheese I've ever tasted.
Moiya McTier
Okay, so I don't know lad means that they're talking to someone
Corinne Caputo
True
Moiya McTier
and the astronauts on the moon, they would not have called each other lad. That would be very disrespectful for people with their status.
Corinne Caputo
Yeah,
Moiya McTier
so I'm going to say that this is false.
Corinne Caputo
You got it. Right. That is correct. That is a quote from Wallace and Gromit. The 1989 Well, it's from a grand day out but it's the 99 Wallace and Gromit movie, that I loved as a kid.
Moiya McTier
Oh my I've never seen it.
Corinne Caputo
It's a claymation and they like go on an adventure and it's fun.
Moiya McTier
I miss claymation
Corinne Caputo
Me too. I love it. There's a few sometimes it comes from my tick tock like some, like indie animators are doing a thing and that's always fun. Okay, let's do two more. Um, quote, didn't I say we might see some purple rocks?
Moiya McTier
No, I like the idea of purple rocks on the moon. So I just for that. I'm gonna say true.
Corinne Caputo
You're right. That was Buzz Aldrin.
Moiya McTier
He spoke!!
Corinne Caputo
he does speak.
Moiya McTier
Good for him. There are purple rocks on the moon.
Corinne Caputo
According to the transcript, that's what they said. A lot of the transcript is like describing the moon to Mission Control.
Moiya McTier
I like that if I told you there would be purple. Yes, like ahead of time. Yeah, he
Corinne Caputo
was like I've been telling you the whole ride. We're gonna see purple rocks
Moiya McTier
Oh, Buzz.
Corinne Caputo
Okay, last one. It's highly likely our moon was built by aliens. We have to get inside and make first contact.
Moiya McTier
Are you fucking kidding me?
Corinne Caputo
this is a tricky one.
Moiya McTier
All right. I'm stumped. I have no idea what it's gonna be no this no one said that on the moon.
Corinne Caputo
No one said that on the moon. That was also Moonfall
Moiya McTier
thank you for letting me flex my detective skills.
Corinne Caputo
Yeah, you're really good at that. I'm gonna have to trick you harder next time.
Moiya McTier
I trained under Sherlock Holmes.
Corinne Caputo
I trained under psych Did you ever watch that show? Oh, I loved I loved psych it's on peacock. Now if you want to watch
Moiya McTier
it again. Oh, nice. It was it was like the the young person's monk.
Corinne Caputo
Yes, exactly. And I also watched monk so it was nice to feel both like mature I'm watching monk and cool and hip. I watched
Moiya McTier
approach from both angles you know Korean I think that I see them bringing out our pasta dishes. They must have like made the pasta from scratch back there because it's been a while
Corinne Caputo
Someone's grandma's back there making this oh
Moiya McTier
I love I love a good like Nona.
Corinne Caputo
Yeah pasta. It's different than others.
Moiya McTier
But remember no matter what you put in your red sauce, you are still made of space
Corinne Caputo
you are space and so is that red sauce
Moiya McTier
pale blue pod was created by Moiya McTier and Corrine Caputo with help from the multitude productions team. Our theme music is by Evan Johnston and our cover art is by Shea McMullen. Our audio editing is handled by the incomparable Misha Stanton,
Corinne Caputo
Stay in touch with us and the universe by following at pale blue pod on Twitter and Instagram. Or check out our website pale blue pod.com were a member of multitude and independent podcast collective and production studio. If you like pale blue pod you will love the other shows that live on our website at multitude dot productions.
Moiya McTier
If you want to support pale blue pod financially, join our community over at patreon.com/pale blue pod for just about $1 per episode, you get a shout out on one of our shows and access to director's commentary for each episode. The very best way though to help pale blue pod grow is to share it with your friends. So send this episode this link to one person who you think will like it and we will appreciate you for forever.
Corinne Caputo
Thanks for listening to pale blue pod. You'll hear us again next week. Bye.