Science Friday - How The Moon Transformed Life On Earth, From Climate to Timekeeping

Episode Date: January 23, 2024

For almost their entire 4.5 billion-year existence, Earth and its moon have been galactic neighbors. And the moon isn’t just Earth’s tiny sidekick—their relationship is more like that of siblings, and they’re even cut from similar cosmic cloth.Without the moon, Earth and its inhabitants wouldn’t be what they are today: The climate would be more extreme, lunar tides wouldn’t have given rise to life on Earth, biological rhythms would be off-beat, and even timekeeping and religion would have evolved differently. The new book Our Moon: How Earth’s Celestial Companion Transformed The Planet, Guided Evolution, And Made Us Who We Are explores how our existence is tied to the moon’s.Ira Flatow and guest host Sophie Bushwick chat with journalist and author Rebecca Boyle about how the moon came to be, how it transformed life on Earth, and how our relationship with it is changing.Transcripts for each segment will be available the week after the show airs on sciencefriday.com Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Moon isn't just Earth's tiny sidekick. It's more like it's smaller, rockier, grayer sibling that is just a special. So much more profound and so much more eternal than these bags of sand, Apollo, towed at home. You know, it's the captain of our existence. It's Tuesday, January 23rd, but you know what else it is? Yeah, it's Science Friday. I'm SciFri producer Rasha Airedi. The Moon is responsible for some of the most important processes that happen here on Earth.

Earth, not just the tides, but migrations, reproduction, circadian rhythms, even how we keep time. Life as we know it is in part thanks to the moon, according to a new book called Our Moon, how Earth's celestial companion transformed the planet, guided evolution, and made us who we are. In this live call-in show, Ira Flato and guest host Sophie Bushwick talk with journalists and author Our Moon, Rebecca Boyle. Welcome to Science Friday. Thanks so much for having me. All right.

This is like a love story. You write about the moon, right? So I'm going to close my eyes, and I want you to take me to the moon. We've traveled. What do I see? Well, we've gone about a quarter of a million miles, and if you're on the surface and you've landed, and it's been a few minutes, hopefully, there's not dust kind of settling still around you in microgravity. you weigh about one sixth of what you weigh on Earth. It is completely silent, except for maybe the beeping of your life support system and your

spacesuit or your spaceship. And there is nothing in front of you but a landscape that only a geologist would love. It's mostly white, mostly gray, but there are flex of color depending on how the sun hits the rocks and maybe how the angle of the sun is falling on your spacecraft or what right in front of your window. It looks very, very desolate and nothing like anywhere you've ever seen on this planet. Let's say I didn't have my spacesuit on. Okay? We know that's the bottom. I wouldn't last long. Would I hear or do smell anything? Would my other senses pick up stuff? You would not hear a thing. There is, it's a total vacuum. So there's no atmosphere to bounce

around or carry it along. You would smell something maybe like the scent of fire, where it works in the Fourth of July after a rainstorm. So like doused fireworks. They're kind of like weird, chemically metal smell of fireworks that have gone off, but another maybe tang along with them and not the tang as not strength. Oh, not the tang. There's a lot of cool things in outer space. So why did you choose to write about the moon?

I'm so partial to the moon. I remember being a kid and sitting on the floor of my school library listening to the Apollo tapes and just kind of being blown away. And I still am. I mean, it's been a long time since people have walked up there. But the idea that humans access this other world, this other planetary type thing and have been there just took my breath away as a kid. And it still kind of does. And I think I write about physics and space a lot.

And the moon kind of is like the forgotten child in that field. Like it's really annoying, actually. It's really bright. And so if you're trying to study, you know, distant galaxies or quasars, it's sort of an obstacle. and I felt like, no, the moon is really cool and we're studying and I want to defend it, you know. You know, it's always dangerous when I go back in my memory. I remember, I think at the 25th anniversary of the first moonwalk, I think it was Arthur C. Clark was asked what was the most amazing thing about going to the moon.

And he said, I think I'm quoting him, is that it's so amazing that we could go there and not go back. Right? That's how wondrous the place was. It's sort of hard to describe, yeah. And I think that it was such a transformative event that the human mind occupied this place and was looking out from it for the first time in history instead of the other way around, which is what we've done forever is look up at it. And that's something we can't ever repeat. And I think it's kind of a profound thing to keep in mind. You know, I think your fascination comes across in the book.

It's really almost a love story about the moon. Yeah, well, I appreciate hearing that. I do think I have a soft spot for the moon. And I think I came at this book with the idea that it's such a fundamental part of, you know, my thinking and who I am and my own family. And then I realized in reporting it that that's the case for really everyone else, too. We have this really profound connection that I wanted to explore. Let's talk. Let's go then right back to the very beginning of the moon because we don't know how exactly it.

came to be, do we? There's debate about why there is a moon. Yeah. This kind of also blows my mind. Like, we should know a lot about this thing. Like, it's right there. It's the moon. Like, we've been to it. How do we not know all these particulars? But it turns out it's just really complicated. And we know something really horrible happened early in Earth's history when Earth was very new that combined and this, it created this world we have now, this paired system of worlds, Earth and the Moon. So something the size of probably Mars thwacked into Earth and both of these things were totally obliterated, like to dust. There's nothing left. There's no evidence of this in a form of a crater or something

like that because they're both just totally vaporized. And somehow they both coalesce into these two different worlds. We don't actually know really how that happened because the physics of it are just so complicated and hard to model. But we think that the Earth and the Moon mixed so completely that they are now basically the same chemically. They're kind of twins in a way. The moon is as much a part of us as we are of it. Wow. So the moon and the Earth were very close together at one point.

When they first formed, yeah, they were united. And so the moon has been moving away all these years. For how many years? I'm very sorry to report that the moon is leaving. Oh, no. One day it will be gone. But that's a very long time from now, so I'm not too worried. Yeah, it is receding from us about the rate at which your fingernails grow, which is not much, you know.

But over the course of millennia, you know, it's not nothing. And eventually it will be far enough away that it will no longer totally eclipse the sun, which will be a bummer. But that's not happening yet. Okay, good. We have one coming up in April. That's right. It is a, don't you find it amazing? I've always found it amazing that it's exactly the right distance away that it creates that total eclipse.

Yeah, this is like my favorite cosmic coincidence. And it's sort of mind-boggling to imagine how rare that would be in the whole universe. I don't know if those conditions obtain literally anywhere else. So other planets with moons don't have total eclipses the way we do? No. I mean, you know, maybe if you like were a being on Jupiter and you could like be in just the right place at just the right time and just the right altitude and distance, maybe one of the moons would like pass in front of the sun in such a way. But the relative sizes of them and the relative distances are so different that it wouldn't look the same.

And those are planets with dozens of moons and you're never going to get one total eclipse out of it. Right. And those are like little crumbs compared to Earth's moon. I mean, those are like dinky, you know, no offense like Ganymede. You know, some of the jovian moons are cool, but they're not special like ours is. And ours is really special. You wrote that the moon actually gave way to life on Earth, starting in the oceans. So how did that happen? Yeah, this came about, this, I guess, realization came about for me when I was looking into the influence of the moon being closer like we're talking about over in millennia ago. And I thought if it was nearer to Earth, you know, a long time ago, probably had a stronger pull on the tide. And there was an interesting study looking at coral growth rings, which is like kind of like tree rings.

You can sort of date corals and understand their environment by looking at these things. And at this one study, there was evidence. that the day was 20 hours long, 400 million years ago. So the Earth's day is also getting longer as the moon is moving away from us. And because it was closer then, the day was shorter, which meant the tide was more powerful. And it turns out that a little after that, like 80 million years, so not a blink of an eye, really, but a little while later. This is when Pangaea is starting to form and ocean basins are closing. So tides are really extreme in this period about 320 million years ago.

in the Devonian. So fish, imagine being a fish in like shallow water in this inlet and there's like an 80-foot change in the height of water over the course of a couple of hours. So you better either get back to the water fast or learn how to breathe the air or walk on the sand, move your body across the land instead of through the water. And the fish that could do that are the ones that gave rise to all of us and all the other backbone vertebrates on land. Let's go to Edward in Adirondack, New York. I have. Edward. Hi. Part of my question has already been addressed, but I know that every artificial satellite, its orbit eventually decays.

And I know that you've already addressed the idea that the moon is going farther away from the Earth. is there any projected idea of how that moving away from the Earth is going to affect Earth itself, like the Tides and every other thing you mentioned? That's cool. Good question. Yeah, well, the good news is that it will be a really long time before anything bad happens. So humans will either be gone or have been uploaded into AI systems like we're trying on the previous hour. This is like hundreds of millions of years in the future. But yeah, it will be a bad day when that eventually happens because the moon helps stabilize the tilt of our axis and keeps our seasons and our climate relatively stable over millennia.

It controls the tide. It, you know, directs the migrations and reproductive cycles of animals. And all of these things will have to either fundamentally change or, you know, just take place in different ways if we don't have the moon. Were you surprised at anything that you uncovered about the moon when you were doing your research? I was surprised at the extent to which it has played such a fundamental role in our concept of ourselves as a species and our understanding of the universe and our place in it. I mean, the moon is the primary way that humans learn to tell time and I think orient ourselves in time. As far as we know, no other animal can do this. Like you can squirrels, you know, for instance, can plan and save food and things like that.

But I don't imagine them saying, and six moons from now, I'm going on vacation or something. the way that we do, you know. And that's a really fundamental shift in thinking. And I think that sort of lays the foundation for this relationship that we've had with the moon the whole time. Let's go right to the phones, which are loaded at this point. Rebecca in Houston, welcome to Science Friday. Hi, nice to see you. Nice to have you. I actually have a great question here. I hope so. Yeah. So I'm actually an nurse engineer here in Houston, but I work more on the

software set of things for the Artemis mission. So I was really curious about the geological side and how they are recreating some of those geological effects in order to help prepare for a return to the moon. What kind of effects you're talking about? Yeah, so maybe the microgravity, as well as the vacuum, how you can combine all of those variables and test for them or even recreate any of that here on Earth. Good question. Let's help her out. What do you think? There's a lot of different ways that, I mean, NASA and other space agencies do this. And one is this really awesome pool that you have at Johnson Space Center that the astronauts can go underwater in their spacesuits and simulate being in microgravity. And just the idea of like moving around in this really

weird environment and you feel super bulky. It's hard to like curl your fist around a tool. And they have to figure out how to do that and manipulate all the technology they need to be using. Also in the desert in Arizona and in Nevada, there are some test beds that. NASA has, that astronauts can kind of hike around in their spacesuits. Also in Hawaii, they've done this before in some of the lava beds. And it gives you maybe not the gravitational sensation the way the pool does, but the maybe physiological or geological sensation of walking on the moon. One of the things that it's hard to recreate, because you mentioned this and you talked

about this in your book, is the actual dust on the moon, right? It's not like anything we have here on Earth. Yeah. This is so hard for people to, I think, remember it because dust on Earth mostly comes from us. I mean, life, you know, in our daily existence, shedding skin and hair and other like bodily materials, you know. But and even if it's rock or sand, it's beaten down. It's weathered. It's soft.

It's, you know, curvy because of the wind and the rain. All these effects that Earth has. Nothing on the moon is like that. It's all jagged. It's all crystalline. It's blocky. And it's really itchy if it gets. it's in your lungs or in your eyes or your nose.

And it drove the Apollo astronauts nuts. Like they couldn't sleep. They were really congested. It felt like having a head cold because they're breathing in this really fine microscopic dust. And it's sharp dust, which is hard to imagine. It would be very, very difficult. You write in the book about the moon in the context of human civilization, particularly early civilizations. Why did it have such an influence throughout history?

I think one thing is easy to forget now. is that, you know, we've only had artificial light at night for 150 years. I mean, being generous, you know, now we have light bulbs everywhere, LEDs, maybe had gas lamps before that for a little while. But up until, you know, the middle of the 19th century, we had the moon. That was it. If you wanted to see at night, you had maybe a lamp, a flame, and you had the moon. And so it was such a powerful luminary that I think people really just relied on it. And it was like a companion. It just, you couldn't miss it. You couldn't not notice it. And you had to notice when it was full or when it was not full, when it was a new moon and it was gone. You would have really noticed that at night. And I think over

time, it just became this sort of like friend for humanity. And I think that ends up sort of morphing into this sort of feeling of thankfulness. Like the moon is helping me see my fields at night or helping me travel these distances. And I really think that's one of the things that leads people to actually worship it early on in the first written. languages. The moon is a really powerful deity, and I think that's probably because of this sort of relationship that we have with it. So many calls. Let's go to Rachel in seaside, California. Hi, Rachel. Thank you so much. This show is a gem for the whole country, and thank you to our author for writing this book. It helps me to love the moon even more. My question, I heard a

wonderful thing that I want to fact check with you because I read it on social media. media seem to have some backup articles. I heard that the moon is responsible in part for maintaining our magnetic field that just as it pulls on the Earth's oceans, it also pulls on the Earth's liquid molten core and kind of creates this dynamo effect that maintains this protective shield that is also responsible for why we have liquid water, life, and all the rest. So I just wanted to know if you had heard, is this true? Well, I invite you to read Chapter 3, which talks about this.

Yeah, I mean, this is one of these things that's difficult to prove geophysically because, like, it's hard to measure the entire magnetic field of Earth in a way that relates to the dynamo and relates to the magma moving around. But, yeah, it's a very valid and active theory that the moon plays this big role in through its tide. mostly through its gravitational pull on Earth. But there is another interesting story about this, which is that this fateful day that this impactor, which we call Pha, came to Earth and, you know,

obliterated Earth and itself. They both remixed and combined into these two worlds. But maybe Thaya is still a part of Earth. There's really recent research looking at these strange provinces underneath Earth's crust that are in its mantle that look like blobs. Like if you could slice Earth in half and look at it, you know, face on, it would look like earmuffs covering the iron core of our planet.

And there is one theory that those little blobs are the remains of Thea. And if that's the case, then yeah, the moon definitely has played a role in creating our dynamo. I love that. I love that image. I'd say bears ears, but you could do fun. Let's go to Doris in Charlotte, North Carolina. Hi, Doris. Hi, how are you doing? Hi there. Good. Go ahead. So my question is about Earth's effect on the moon. Everyone talks about all of the things that happens to Earth because of the moon.

And we all know a lot of how the Moon affects Earth, but how does Earth affect the Moon? Does it, like as it grows, as it moves further and further away from Earth, is it going to change as well? And what kind of changes would occur? Great question. Thank you, Your Honor. And, yeah, the answer is yes. It's so interesting in the ways in which this happens. One of the most fundamental is the weird disparity between the near side and the far side of the moon.

So they look really different at like both just looking at them and just chemically. They seem very distinct. And one theory for why that is is that Earth maybe warmed the near side of the moon when it was closer when it was first cooling off. And the way that the moon differentiated and cooled down into this rocky sphere changed because Earth was here keeping it toasty. Another one is that the moon has this very fine, tenuous layer of oxygen, actually, which comes from us. Oxygen is really reactive, and so it likes to go into rocks and it likes to bond with iron and make rust and things like that. So it doesn't last very long unless life is here making it. And as we know, that's why we have a very oxygen-rich atmosphere.

So sometimes when the moon and the earth and the sun are lined in such a way that the solar wind is blowing onto Earth. and then onto the moon after that, some of the oxygen in our atmosphere is blown all the way to the moon, which is this little evidence that we are here and we are alive. And at some point, when the moon's far enough away, that one the longer be the case. This is really romantic. It is. View of the moon. But to go to a little more practical idea, you talk in the book about timekeeping and about the use of the sun versus the moon and how those kind of combine.

I mean, can you talk to us a little bit about how we got our calendar based on the moon? Yeah. So the moon is kind of the most obvious way to mark time beyond a day because it changes every night. It comes back every month. I mean, the word month comes from the moon. It's an old English word, moonth. And that's how we figured out that we could plan ahead a few weeks at a time. And the seven-day week is derived from dividing up the lunar cycle by four.

And so it's sort of the way we used to mark our lives. And I think that ends up translating into this really interesting phenomenon where people who figured out how to marry the lunar calendar with the solar calendar have a kind of form of power over one another because they're not exactly aligned. There are about 12 moons in a solar gear. So in the time it takes for the solstices to recur, which we just had here in the northern hemisphere. It was winter solstice a month ago. There's about a 12-day difference. The 12 days of Christmas actually is a holdover from this. They're 354 days in a lunar year, but 365.25 solar days.

So over a couple years, like, your calendar is going to be off by a month, you know, and your harvest festival is going to fall in the middle of the growing season. And so people had to figure out a way to reset the calendar if they're going to use the moon to mark their year. And there's a lot of ways to do this. The Maya figured this out. I mean, ancient Sumerians figured this out. People all over Earth figured out ways to do this. The, you know, pharaohs in Egypt.

once you did that and you had a tool or a device or some method for figuring this out, then you are the one that says, this is when the new year begins. I'm the guy in charge. And that ends up creating a system of control. You know, it's been more than 50 years since the Apollo missions put people on the moon. And there was a little quiet period, I mean, quiet decades. Yeah, yeah. And now we're trying to, there's so many landers and we're trying to put people back on the moon.

Right. Can you give us a sort of a rundown of what's going on with all these attempts? I mean, just this week, there's been so much news on the moon. It's really crazy. There was a launch on a few days ago of this first commercial lunar lander, which is not going to be the first lander now. It burned up in the atmosphere yesterday, unfortunately, for this team. And then today, just a couple hours ago, Japan landed a small lander on the moon,

becoming the fifth country to do so. We're not sure exactly if it's okay. Like there's some questions about whether or not it is going to get power or how it may have rolled over. We're not totally sure. And it's midnight right now in Japan. So the press conference, they all went to sleep. But yeah, the fact that there's so much happening right now is just a reflection of our continued interest, I think. It's always going to be a place that we want to imagine going and being.

And that interest in going there, what does that tell us about our relationship with the moon? I think right now it's changing. It's about to change in very fundamental ways. And I think being there permanently, you know, looking out from it at Earth permanently, the way that maybe we do on the space station. You know, it's not like there's going to be a city up there anytime soon or some sort of settlement. But I do think that there will be people up there coming and going and living in really austere conditions probably, you know. But and trying to do science, trying to do research, maybe trying to go prospecting for resources and to make money. and all these different human things.

And I think that's going to really fundamentally change the way we view the moon. And it becomes a little bit more of an extension of Earth than it already is and more of an extension of us than it already is. Ed on Twitter, right, sort of in your vein, how is the moon being used as a launch site for a Mars mission? This is one of the things NASA likes to talk about. They have moon to Mars as kind of NASA lingo for one reason for doing Artemis, which is this sister of Apollo, you know, new human landing program.

And, you know, I don't know. Sometimes I think of that meme where it's like the guy walking with his girlfriend and like turning around to look at another woman and the girlfriend's like, hey, you know, that's how I feel like the moon is like that girlfriend being like, bud, what about me? Moon is cool. Like, why does the moon be a stepping stone for somewhere else? The moon is interesting in his own right. But yeah, I mean, that's one reason why people want to go up there and look around for things like water. Because if you can mine for water and separate its hydrogen and oxygen and refine that, then you have rocket fuel. And so you can take less with you off Earth and then get to Mars maybe more easily.

And there's also a lot of controversy about how we've been using the moon lately, right? Like the Navajo Nation has been in the news lately with the launch of a private mission. Can you talk about that a little? Yeah, this was really interesting. And this is in my book, too, that this happened 25 years ago as well. and it seems like history repeats itself. But there was this commercial lander that took off not long ago now. It was carrying these small capsules that contained a very small amount of cremated human remains.

On behalf of these people's loved ones wanted to send small amounts of their ashes to the moon forever as a way of memorializing them. But to the Navajo people, the moon is sacred. It's grandmother moon is a really powerful symbol in the Navajo Dene culture. And they were really upset by this. And the president of the Navajo Nation emailed NASA and said, please delay this launch. You know, this is desecration of a place that we consider holy. No one even asked us, you know. And I think no one really asked anyone is the thing.

And the moon belongs to everyone. We need to consider everyone when we start sending relics or material or even humans back up there. And yeah, that was a good example of how this is happening on a timescale that I think is happening faster than people are expecting. And it's going to be more of an issue as more people try to go to the more. Yeah. And the thing is, these are commercial companies. They can take whatever they want to take. Anybody that wants to pay them to send something, they'll send it. And that could be cremated human remains. It could be a Bitcoin. You know, it could be, there's actually a sculpture going on the next commercial Lunar Lander made by the artist Jeff Coons. There's a small time capsule.

You know, it could be almost anything you could imagine. And that's going to raise some questions. And there's political questions about the moon, too, about all these people going there. And what they're leaving, we've left discs and flags and things like that. Yeah, anything on the moon is almost like staking a claim. You know, it's not legally like that per se. But the complexity around access to space and access to the moon is very, very interesting right now. And there's not really a good framework for deciding who gets to go and where. And what do you think we owe the moon?

This is a good question. I mean, this is kind of like the framing of my entire book, I think, is like I just want people to consider what it has represented to humanity so much more profound and so much more eternal than these bags of sand, Apollo, tooted home. You know, it's the captain of our existence. I think we at least owe it a discussion about that and about its prominence in our lives and its meaning to us. Yeah. Well, thank you very much for taking time to be with us today. Thanks so much for having me. This was fun. Lots of people help make this show happen, including...

Jason Rosenberg. George Harper. Kathleen Davis. Shoshana Bugsbaum. I'm SciFri producer, Rasha Eredi. On tomorrow's show, we celebrate the Apple Macintosh's 40th birthday and learn how the PC came to be. Join us.