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Speaker 4: Like a good neighbor.

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Speaker 4: Proud sponsor of Mykutura podcast network.

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Speaker 1: Hey Kelly, I have a controversial question for you.

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Speaker 4: Oh boy, coming from you that makes me particularly nervous.

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Speaker 4: Is this another episode I'm gonna have to make sure

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Speaker 4: my kids don't listen.

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Speaker 1: To no, but it might cause some other kind of

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Speaker 1: family drama.

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Speaker 4: Okay, now you have my attention.

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Speaker 1: Well, you know, since you're married to a cartoonist, I'm

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Speaker 1: wondering if I'm allowed to ask you whether you're a

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Speaker 1: fan of a different cartoon.

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Speaker 4: Well, that depends if it's a rival cartoon or not.

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Speaker 1: So I'm wondering if you have a favorite cartoon from

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Speaker 1: the Far Side.

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Speaker 4: Oh, I mean he hasn't updated for a while, right,

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Speaker 4: I mean, I suppose he's still competition. But anyway, all right,

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Speaker 4: let's see, let's see. Uh, so hard to pick so

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Speaker 4: many favorites. So there's one where there's a slide, you know,

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Speaker 4: like a kid's playground, and some spiders have built a

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Speaker 4: net or a web along the bottom, and one spider

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Speaker 4: is saying something like, uh, if we can pull this off,

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Speaker 4: we'll never be hungry again, nor something like that. And I,

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Speaker 4: as an invert person, just thought that was that was amazing.

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Speaker 4: And of course I liked the like School for the Gifted,

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Speaker 4: the one that was on T shirts when I was

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Speaker 4: a kid.

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Speaker 1: What about you, Well, I have to ask you, do

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Speaker 1: you see that spider's eating a baby cartoon? Differently now

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Speaker 1: that you're a parent?

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Speaker 4: No, still hilarious.

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Speaker 1: US. I think your children should be terrified if they

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Speaker 1: listen to this episode.

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Speaker 4: Probably, Oh my gosh, poor kid won. The other day

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Speaker 4: I told her to go get a bowl in my office,

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Speaker 4: and she thought it was going to have something like

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Speaker 4: candy in it. But she accidentally picked up the bowl

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Speaker 4: of dead insects that I found in the barn that

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Speaker 4: I was thinking of pinning at some point, and they

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Speaker 4: were all over my office. So she must have seen

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Speaker 4: it and thrown it up in the air and they

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Speaker 4: went all over. My kids are going to have very

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Speaker 4: high therapy bills at some point, but I love them

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Speaker 4: very much.

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Speaker 1: I think that living in your house must be even

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Speaker 1: weirder than the Far Side Cartoon, almost certain. Hi. I'm Daniel.

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Speaker 1: I'm a particle physicist and a professor at UC Irvine,

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Speaker 1: and I don't think I've yet traumatized my children with insects.

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Speaker 4: Hi, I'm Kelly Wiener Smith, and I study creepy crawley

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Speaker 4: things at Race University, and I'm traumatizing kids all the time.

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Speaker 1: Education through trauma is set your strategy.

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Speaker 4: That's a good way to make people remember.

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Speaker 1: Stuff where you live out on the farm, but there's

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Speaker 1: lots of access to creepy crawley weird things, and so

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Speaker 1: I hope your kids are become ver acclimatized to.

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Speaker 4: That I'm making them because.

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Speaker 1: It takes a brave soul to explore the nature of

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Speaker 1: the universe, or even just your backyard, depending on what's

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Speaker 1: slithering out there. So whether or not you turn your

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Speaker 1: eyes down to the ground or up to the skies,

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Speaker 1: there's a whole lot of stuff to wonder about, and

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Speaker 1: so welcome to the podcast. Daniel and Jorge explain the

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Speaker 1: universe in which we do all of that wondering. We

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Speaker 1: think about everything that's between your toes and everything that

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Speaker 1: your eyes can gather as you look up into the

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Speaker 1: night sky. We think about what's on the moon, what's

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Speaker 1: on the backside of the moon, and what's in the deepest,

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Speaker 1: darkest depths of the universe. We chew all of it

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Speaker 1: up and try to digest it and explain it to you.

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Speaker 4: And it's not always pretty.

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Speaker 1: Sometimes the truth is just gross. My typical co host

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Speaker 1: and friend, Jorge Champ, can't be here today, so I'm

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Speaker 1: very glad to have one of our regular guest hosts, Kelly. Kelly,

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Speaker 1: thanks very much for joining us again and terrifying your children.

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Speaker 4: Yeah, well, I hope I could terrify some people today too.

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Speaker 4: Thanks for having me back.

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Speaker 1: But today we're not talking about the weird, creepy crawley

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Speaker 1: bits that are inside Kelly's pantry. Strange as that might be,

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Speaker 1: we are turning our eyes to the sky tonight. We

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Speaker 1: are thinking about what's out there in the universe and

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Speaker 1: what we can see and what we can't see, and

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Speaker 1: how the gravitational forces that have built the structure of

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Speaker 1: our universe also limit what we can see out there.

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Speaker 1: If you were a kid like me, then you spent

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Speaker 1: a lot of time looking up at the night sky,

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Speaker 1: not just absorbing the stars, but also gazing on the

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Speaker 1: closest object that's out there, the biggest, fattest thing in

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Speaker 1: the night sky, and that's, of course our moon. It

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Speaker 1: has so many fascinating features to it, but one of

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Speaker 1: the most interesting features is that you always see the

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Speaker 1: same features. Kelly, do you remember understanding this as a

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Speaker 1: kid or wondering about why you're always seeing the same

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Speaker 1: bits on the moon?

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Speaker 4: You know, I really wish you hadn't asked me that,

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Speaker 4: because the answer is, when I was a kid, I

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Speaker 4: didn't realize I was always seeing the same side of

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Speaker 4: the moon. That hadn't really hit me until I think, baby,

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Speaker 4: I was in college, and then I was like, wait

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Speaker 4: a minute, and I guess I just wasn't I was

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Speaker 4: looking down at the salamanders and not up at the sky.

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Speaker 4: But so no, that is not a question I had

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Speaker 4: when I was a kid, but it should be when

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Speaker 4: did you learn this?

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Speaker 1: I remember learning about it, I think when I was

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Speaker 1: seven or eight. But you know, my dad was pretty

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Speaker 1: into astronomy and into science, and so we talked about

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Speaker 1: this kind of stuff. One thing I'm still curious about, though,

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Speaker 1: is when humanity understood that, or when humanity understood it?

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Speaker 1: Was an interesting question, like did ancient Chinese astronomers, who

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Speaker 1: spend a lot of time looking up at the Moon

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Speaker 1: and predicting its eclipses, did they figure out that the

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Speaker 1: moon was a sphere and that it was rotating and

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Speaker 1: that it was weird that we always saw the same

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Speaker 1: side of it? Or is this just something they overlooked?

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Speaker 4: Do you know the answer to that question.

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Speaker 1: I don't know the answer to that question. I've been

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Speaker 1: digging through the history of astronomy a little bit, and

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Speaker 1: I know that Newton understood it because of his ideas

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Speaker 1: about gravitation, but digging deeper into history, it's not really

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Speaker 1: discussed very much, and I sort of wonder if people

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Speaker 1: suspected that it was just a coincidence that the Moon

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Speaker 1: rotates at this perfect rate, just so that we can

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Speaker 1: only see one side of it, because you know, there

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Speaker 1: are other fascinating coincidences about the moon. For example, the

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Speaker 1: moon and the Sun happen to be the same size

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Speaker 1: in our sky, right, the Sun is much much bigger,

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Speaker 1: but much much further away, and those two numbers line

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Speaker 1: up perfectly. So the Sun and the Moon appeared to

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Speaker 1: be the same size, which is why we can get

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Speaker 1: so many fascinating eclipse effects. And that, of course, is

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Speaker 1: just a coincidence. There's no like deep reason for that.

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Speaker 1: It just happens to be. These two numbers just kind

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Speaker 1: of line up in our.

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Speaker 4: Universe, and humans are notoriously tripped up by coincidences, exactly.

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Speaker 1: And so I think ancient astronomers must have wondered about

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Speaker 1: that size, and I wonder if they also wondered about

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Speaker 1: the rotation of the moon, if they understood that. Now,

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Speaker 1: I do know that ancient Chinese astronomers had a little

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Speaker 1: bit of a disadvantage compared to, for example, ancient Greek

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Speaker 1: astronomers because they didn't have geometry. Right, we think about

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Speaker 1: the universe in terms of geometry. You imagine how clips

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Speaker 1: has happened, and you think, probably in your head you

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Speaker 1: have a mental picture of all these things happening and

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Speaker 1: to explain it. But Chinese astronomers didn't develop geometry, so

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Speaker 1: they didn't have the same sort of geometrical thinking that

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Speaker 1: we're all very familiar with. Instead, they had like tables

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Speaker 1: of numbers, and they had arithmetic, and they could manipulate

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Speaker 1: these numbers to do their predictions. So I think they

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Speaker 1: must have thought about these things very differently than we did.

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Speaker 4: Interesting, it's nice to have our modern tools.

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Speaker 1: Thank you to those folks who invented geometry. It turns

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Speaker 1: out to be pretty.

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Speaker 4: Useful quote unquote modern.

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Speaker 5: Yeah.

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Speaker 4: Right.

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Speaker 1: And so we have been looking up in the night

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Speaker 1: sky and looking at the moon and seeing the same

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Speaker 1: side of it for thousands and thousands of years, and

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Speaker 1: now of course we understand why. And so today on

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Speaker 1: the podcast, we're going to be digging into the physics

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Speaker 1: of the far side of the moon and many other

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Speaker 1: objects in our solar system that exhibit the same behavior.

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Speaker 1: On today's episode, well, I answer the question what is

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Speaker 1: tidal locking?

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Speaker 4: And this is another thing that connects us to the

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Speaker 4: dinosaurs right, because they also would have seen the same

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Speaker 4: side of the moon.

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Speaker 1: If dinosaur geometers had figured that out, boy, they could

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Speaker 1: have written a paper and got a lot of citations.

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Speaker 4: They really could have, and then maybe they could have

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Speaker 4: started a you know, NASA and had an asteroid deflection program.

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Speaker 4: Everything could have been different.

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Speaker 1: You sound like you're kind of hoping for that, but

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Speaker 1: you know, in that scenario, we don't exist.

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Speaker 4: Oh, good point.

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Speaker 1: We're rooting for the asteroid on that one.

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Speaker 4: That's right, we sure are.

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Speaker 1: I'm sorry dinosaurs, which puts us on the anti Math

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Speaker 1: Education for Dinosaurs committee as well.

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Speaker 4: It's an uncomfortable place to be. But no, it doesn't

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Speaker 4: feel very good, but I'm firmly in this position. Yeah.

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Speaker 1: So this is a topic that affects our Moon and

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Speaker 1: affects our planet, and affects a lot of things in

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Speaker 1: the Solar System and in other Solar system. It's a

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Speaker 1: fascinating little bit of physics. So I was curious what

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Speaker 1: people knew about the topic of title locking and if

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Speaker 1: they understood the physics of it. So I went out

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Speaker 1: there into the Internet to ask folks if they understood this.

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Speaker 1: Thanks very much to those of you who participate in

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Speaker 1: this segment of the podcast to let us know what

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Speaker 1: people think about the topic of the day. If you'd

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Speaker 1: like to hear your voice for a future episode, please

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Speaker 1: don't be shy. Write to me too questions at Danielandjorge

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Speaker 1: dot com. So think about it for a minute. Do

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Speaker 1: you understand the physical of tidal locking. Here's what some

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Speaker 1: listeners had to say.

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Speaker 6: So, I believe that tidal locking is when, say, a

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Speaker 6: planet has a moon that's locked in orbit at a

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Speaker 6: certain distance, so the tides are always the same. So

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Speaker 6: I guess you could say that we're in tidal locking

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Speaker 6: because day in and day out, our tides go the

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Speaker 6: same because.

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Speaker 1: The moon's in a fixed orbit.

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Speaker 4: Tidle locking is just like our moon. We see the

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Speaker 4: same face of it at all times.

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Speaker 6: It has no spin, and the dark side of the

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Speaker 6: moon is facing outward.

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Speaker 4: It is the deformation that a celestial body so first

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Speaker 4: when it's orbiting or is orbited by another massive celestial body.

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Speaker 5: Tidal locking is when a lower mass body is orbiting

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Speaker 5: a much higher mass body and the same side always

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Speaker 5: faces it. So I know that we always see the

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Speaker 5: same side of the moon. Means tidally locked to the Earth.

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Speaker 4: I was impressed that none of the listeners seemed totally

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Speaker 4: stumped by this, because I feel like title locking is

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Speaker 4: not necessarily something that you hear, like that, at least

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Speaker 4: there's a phrase I don't hear very often, and so like,

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Speaker 4: it seems like some people knew exactly what you were

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Speaker 4: asking about, and none of them were like me when

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Speaker 4: I was a kid, and we're just totally unaware that

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Speaker 4: this is a thing that was happening.

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Speaker 1: Yeah, we got some pretty well educated listeners. The word

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Speaker 1: title I think makes some people think of tides, which

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Speaker 1: is connected, of course to tidal forces, you know, like

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Speaker 1: the moon pulls on the Earth and squishes its oceans

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Speaker 1: and makes us have higher tides in some places and

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Speaker 1: lower tides and other places. But that's not what we

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Speaker 1: mean by title locking. Title locking is actually a different

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Speaker 1: phenomena we're going to dig into today. But thank you

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Speaker 1: very much to all of our volunteers. We really cherish

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Speaker 1: your thoughts.

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Speaker 4: Yeah, you have a smarter than average audience, I think,

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Speaker 4: or smarter than Kelly average audience. I'm always impressed by

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Speaker 4: the answers.

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Speaker 1: They're smart and they're good looking too.

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Speaker 4: That's right. I think that's called the halo effect when

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Speaker 4: you know what good thing about them, and you assume

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Speaker 4: you know all the good things about them.

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Speaker 1: So let's dig into the physics of tide locking what

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Speaker 1: it is, what's going on, and why I play such

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Speaker 1: a big role in what we see in our night sky.

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Speaker 1: And I think the first thing to understand is just

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Speaker 1: like the geometry of what's going on. Obviously, the Moon

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Speaker 1: is orbiting the Earth, and the Earth is spinning, and

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Speaker 1: the Moon is spinning around the Earth, and the Moon

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Speaker 1: is also spinning on its axis, so there's sort of

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Speaker 1: a lot of spinning going on. But you got to

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Speaker 1: get all that spinning in your head to understand, like

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Speaker 1: why we only see one side of the moon.

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Speaker 4: Yes, so I am staring directly ahead trying to picture everything,

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Speaker 4: So go ahead, what should I be imagining?

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Speaker 1: So first, just put yourself on the Earth and forget

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Speaker 1: the fact that the Earth is spinning, and just move

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Speaker 1: the Moon around the Earth in your mind and imagine

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Speaker 1: the Moon is like a shoe or something. If the

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Speaker 1: Moon is not spinning, it's just orbiting the Earth, then

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Speaker 1: the Earth is going to see different sides of the shoe.

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Speaker 1: It's going to see the back of the shoe. It's

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Speaker 1: going to see the front of the shoe because as

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Speaker 1: the shoe moves around the Earth, different sides of it

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Speaker 1: are going to be closer to the Earth or closer

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Speaker 1: to outer space.

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Speaker 4: So the shoe is not rotating either.

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Speaker 1: That's right. So first the shoe is not rotating, and

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Speaker 1: so we see one side of it, and then we

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Speaker 1: see the other side of it. So if the shoe

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Speaker 1: or the moon or whatever is not spinning, then you

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Speaker 1: would see different sides of it. Right now, the Moon,

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Speaker 1: of course is spinning. It's spinning on its axis. But

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Speaker 1: if it was spinning at some random rate, like really

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Speaker 1: really fast or really really slow, you would still see

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Speaker 1: both sides of it because eventually it would spin in

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Speaker 1: a way that revealed every part of the Moon. The

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Speaker 1: only way for us to not be able to see

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Speaker 1: part of the Moon is for its spin to be

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Speaker 1: perfectly syncd up with its orbit, so that as it

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Speaker 1: goes around the Earth, it turns just the right amount

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Speaker 1: every second, so the same side of it is always

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Speaker 1: facing the Earth, like if the back side of the

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Speaker 1: shoe is always facing the Earth. Because the shoe itself

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Speaker 1: is spinning at just the right rate as it goes

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Speaker 1: around the Earth.

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Speaker 4: And everyone on every part of the Earth is always

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Speaker 4: seeing the same side of the moon. Right, It's not

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Speaker 4: like you know, in the US you see one side,

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Speaker 4: in Chinese the other side or right, you're always seeing

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Speaker 4: the same side.

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Speaker 1: That's right. The same side of the Moon is always

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Speaker 1: closer to the Earth, and the other side of the

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Speaker 1: moon that we call the far side, which I assume

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Speaker 1: is the origin of the name of the far Side

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Speaker 1: and comic it's always facing outer space. And this is

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Speaker 1: the sort of coincidence we were talking about, Like these

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Speaker 1: two numbers, the rate at which the Moon goes around

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Speaker 1: the Earth and the rate at which the Moon spins

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Speaker 1: around its axis have to be perfectly synced up to

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Speaker 1: get this effect.

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Speaker 4: And why are they perfectly syncd up. Is this one

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Speaker 4: of the few instances in which we have something special

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Speaker 4: going on and they just happen to sync up? Or

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Speaker 4: are we just like every other moon Because this happens

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Speaker 4: all the time.

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Speaker 1: So it's not that special and it's not a coincidence,

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Speaker 1: but it's not something that's always happened. Like to really

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Speaker 1: get into it, you have to understand the history of

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Speaker 1: the formation of the moon, like how did it get

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Speaker 1: made how is it spinning originally? And then how has

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Speaker 1: that changed? You know, our moon is not just like

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Speaker 1: some object that we captured as it was flying by.

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Speaker 1: We think that the Moon actually comes from a huge

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Speaker 1: collision something like one hundred million years after the Earth

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Speaker 1: was formed. So we're talking like four point four billion

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Speaker 1: years ago. You have some like very hot proto Earth.

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Speaker 1: It got slammed into by some giant Mars sized planet

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Speaker 1: they called Fea, And so you're talking about a huge

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Speaker 1: collision like Earth versus Mars in space, and both objects

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Speaker 1: are essentially vaporized.

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Speaker 4: But we still have thirst in the moon.

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Speaker 1: You're like, how that to current reality? You know, you're

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Speaker 1: exactly right. It got vaporized, but then it coalesced. Right.

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Speaker 1: Gravity is very very patient, and so even though all

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Speaker 1: of its original work in the first one hundred million

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Speaker 1: years was ruined by this collision, it got back to

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Speaker 1: work and it pulled those blobs together and it made

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Speaker 1: two new blobs, one that formed the Earth and then

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Speaker 1: a big ring around the Earth, like a ring of

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Speaker 1: debris that was spinning sort of too fast around the

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Speaker 1: Earth to fall into the central plump, which formed this

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Speaker 1: like huge spray of material.

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Speaker 4: All right, So and that's why the Moon's made out

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Speaker 4: of the same stuff the Earth is made out of.

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Speaker 1: Exactly when we visited the Earth first and we sampled it,

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Speaker 1: people were surprised to discover that it's basically the same

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Speaker 1: mixture of stuff as the Earth. It's not like a

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Speaker 1: different Solar System body that was formed in another place,

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Speaker 1: and so it has a different mixture of like ices

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Speaker 1: and rocks and different isotopes and stuff. It's basically made

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Speaker 1: out of the same stuff as the Earth. And that's

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Speaker 1: because it comes from the same mixture of those two planets.

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Speaker 1: Like it was the same vaporized blob of stuff, and

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Speaker 1: some of it fell in towards the Earth, and the

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Speaker 1: stuff that was spinning around sort of too fast ended

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Speaker 1: up in this big debris ring, but then gravity pulled

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Speaker 1: that together into a moon.

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Speaker 4: Did we have this hypothesis before we went to the

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Speaker 4: Moon and found what it was made of, or did

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Speaker 4: going to the Moon and physically collecting samples give us

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Speaker 4: this hypothesis when we were like, whoa, it's the same stuff.

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Speaker 1: This hypothesis has been around for a while, but it

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Speaker 1: really became the favorite once we went to the Moon,

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Speaker 1: and also once we understood something about the Moon's inner core.

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Speaker 1: The Moon has sort of a small iron core, smaller

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Speaker 1: than you would expect, and the hypothesis is that a

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Speaker 1: lot of that iron was probably lost from when the

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Speaker 1: impactor hit the proto Earth, and some of that was

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Speaker 1: like melted and vaporized, and so it would have a

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Speaker 1: bigger iron core otherwise. This became a much more popular

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Speaker 1: hypothesis after we went to the Moon and visited and

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Speaker 1: understood what it was made out of. And there's a

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Speaker 1: lot of really interesting physics there that's relevant to it,

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Speaker 1: Like why doesn't it all just collapse into a planet, right,

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Speaker 1: Why doesn't it all just become one huge giant planet.

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Speaker 1: How come part of it ended up as a ring?

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Speaker 1: And that's just because you know, the whole thing is

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Speaker 1: spinning and a lot of it has angular momentum, and

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Speaker 1: so some stuff was just moving too fast to fall

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Speaker 1: in the way like the moon now is moving too

402
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Speaker 1: fast to fall into the Earth. It's all about that velocity.

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Speaker 1: And then when that stuff gathered together into a moon,

404
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Speaker 1: that stuff was spinning. So the moon had some original spin, right,

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Speaker 1: that came from the spinning motion of all of that stuff.

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Speaker 1: After the vaporization, we think that spin rate originally was

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Speaker 1: much much higher than it is today, So the Moon

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Speaker 1: used to be spinning faster than it is now.

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Speaker 4: Was there this is maybe an unfair question. Was there

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Speaker 4: anything alive on Earth when it was spinning fast enough

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Speaker 4: that sometimes you'd see what is now the far side

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Speaker 4: of the moon. So like dinosaurs probably never saw the

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Speaker 4: far side of the Moon, but did like the first

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Speaker 4: bacteria see the far side of the Moon. I mean,

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Speaker 4: I'm sure they don't see anything that far away, but

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Speaker 4: you know, could they have?

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Speaker 1: Yeah, it's possible. We don't really know exactly how old

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Speaker 1: life is on Earth, but it stretches back billions of years, right,

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Speaker 1: and so it's possible that there are critters that have

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Speaker 1: lived on Earth that have seen other parts of the Moon.

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Speaker 1: That's a very cool thought, because the Earth has been

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Speaker 1: gradually slowing down the Moon's spin little by a little

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Speaker 1: every year. And the opposite is also true. But you know,

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Speaker 1: until nineteen fifty nine, no human had ever seen the

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Speaker 1: backside of the Moon. It was this like dark spot

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Speaker 1: in our vision that we just couldn't no matter how

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Speaker 1: many thousands of years we've been staring up at the Moon,

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Speaker 1: nobody had ever laid eyes on the backside until nineteen

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Speaker 1: fifty nine, which feels really recent.

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Speaker 4: Right, And the Soviets did.

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Speaker 1: It right, Yeah, they certainly did.

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Speaker 4: Yeah, they beat us there with the lunar program. Their

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00:20:15,520 --> 00:20:17,600
Speaker 4: third one made it there. I think the first two

434
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Speaker 4: maybe blew up. That was a thing that happened a

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Speaker 4: lot for the Soviets. But anyway, so.

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Speaker 1: Sorry, no, there's a really fun set of stories there.

437
00:20:26,680 --> 00:20:29,080
Speaker 1: Maybe you know about because of your book research, that

438
00:20:29,119 --> 00:20:30,960
Speaker 1: the Soviets were there first and so they got to

439
00:20:31,080 --> 00:20:32,879
Speaker 1: name a lot of stuff on the far side of

440
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Speaker 1: the moon first, so they have all these Russian names

441
00:20:35,720 --> 00:20:38,760
Speaker 1: and that like really annoyed the Americans at the time.

442
00:20:39,000 --> 00:20:42,440
Speaker 1: And then you know, later this International Astronomical Union took

443
00:20:42,480 --> 00:20:44,480
Speaker 1: over the naming, so it wasn't all just you know,

444
00:20:44,840 --> 00:20:46,800
Speaker 1: named after kinds of vodka or whatever.

445
00:20:47,119 --> 00:20:52,280
Speaker 4: All come now, that's an unfair stereotype. Did the IAU

446
00:20:52,560 --> 00:20:55,320
Speaker 4: change any of the names that the Soviet program had

447
00:20:55,359 --> 00:20:58,120
Speaker 4: put in place, or they just like stopped the Soviets

448
00:20:58,119 --> 00:20:59,240
Speaker 4: from doing any more naming.

449
00:20:59,560 --> 00:21:01,239
Speaker 1: I think to just stop them. And there's a lot

450
00:21:01,280 --> 00:21:04,000
Speaker 1: of respect, I think for the people who discover something

451
00:21:04,080 --> 00:21:06,160
Speaker 1: to name it. But then I think that the Civiets

452
00:21:06,160 --> 00:21:08,159
Speaker 1: were so far ahead that they didn't want them to

453
00:21:08,200 --> 00:21:11,160
Speaker 1: just like name the whole thing after their favorite Soviet

454
00:21:11,200 --> 00:21:12,280
Speaker 1: flower or whatever.

455
00:21:12,520 --> 00:21:15,639
Speaker 4: Thank, yes, there we go. That's good. That's good. I

456
00:21:15,640 --> 00:21:18,080
Speaker 4: think there is like a Gagaran and seas or something

457
00:21:18,160 --> 00:21:20,640
Speaker 4: like them. All right, so we're gonna take a quick

458
00:21:20,640 --> 00:21:22,560
Speaker 4: break and then we'll talk about what they found on

459
00:21:22,600 --> 00:21:23,360
Speaker 4: the far side.

460
00:21:23,160 --> 00:21:29,960
Speaker 1: Of the moon. With big wireless providers, what you see

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472
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483
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500
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Speaker 1: When you pop a piece of cheese into your mouth

501
00:23:31,400 --> 00:23:34,520
Speaker 1: or enjoy a rich spoonful of Greek yogurt, you're probably

502
00:23:34,600 --> 00:23:38,639
Speaker 1: not thinking about the environmental impact of each and every bite,

503
00:23:38,680 --> 00:23:41,280
Speaker 1: But the people in the dairy industry are. US Dairy

504
00:23:41,320 --> 00:23:45,600
Speaker 1: has set themselves some ambitious sustainability goals, including being greenhouse

505
00:23:45,640 --> 00:23:48,480
Speaker 1: gas neutral by twenty fifty. That's why they're working hard

506
00:23:48,560 --> 00:23:51,000
Speaker 1: every day to find new ways to reduce waste, conserve

507
00:23:51,119 --> 00:23:54,880
Speaker 1: natural resources, and drive down greenhouse gas emissions. Take water,

508
00:23:54,920 --> 00:23:58,520
Speaker 1: for example, most dairy farms reuse water up to four times.

509
00:23:58,560 --> 00:24:01,920
Speaker 1: The same water cools the milk clean's equipment, washes the barn,

510
00:24:02,040 --> 00:24:05,760
Speaker 1: and irrigates the crops. How is US dairy tackling greenhouse gases?

511
00:24:05,800 --> 00:24:08,800
Speaker 1: Many farms use anaerobic digestors that turn the methane from

512
00:24:08,800 --> 00:24:12,199
Speaker 1: maneuver into renewable energy that can power farms, towns, and

513
00:24:12,240 --> 00:24:14,480
Speaker 1: electric cars. So the next time you grab a slice

514
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Speaker 1: of pizza or lick an ice cream cone, know that

515
00:24:16,440 --> 00:24:19,119
Speaker 1: dairy farmers and processors around the country are using the

516
00:24:19,200 --> 00:24:22,960
Speaker 1: latest practices and innovations to provide the nutrient dense dairy

517
00:24:22,960 --> 00:24:25,640
Speaker 1: products we love with less of an impact. Visit us

518
00:24:25,720 --> 00:24:28,240
Speaker 1: dairy dot com slash sustainability to learn more.

519
00:24:29,280 --> 00:24:32,800
Speaker 2: There are children, friends, and families walking, riding on passing

520
00:24:32,840 --> 00:24:34,919
Speaker 2: the roads every day. Remember they are real people with

521
00:24:35,000 --> 00:24:37,360
Speaker 2: loved ones who need them to get home safely. Protect

522
00:24:37,359 --> 00:24:40,399
Speaker 2: our cyclists and pedestrians because they're people too, Go safely.

523
00:24:40,440 --> 00:24:43,320
Speaker 2: California from the California Office of Traffic Safety and Caltrans.

524
00:24:51,840 --> 00:24:53,360
Speaker 4: The first time we got to see the first side

525
00:24:53,359 --> 00:24:56,399
Speaker 4: of the moon was nineteen fifty nine. Not too long

526
00:24:56,480 --> 00:24:59,840
Speaker 4: after that, the Apollo astronauts were flying around the Moon.

527
00:25:00,000 --> 00:25:02,520
Speaker 4: We got to see the far side. What kinds of

528
00:25:02,560 --> 00:25:05,280
Speaker 4: things were over on the far side To see Daniel, Well.

529
00:25:05,160 --> 00:25:08,280
Speaker 1: You know, in research, it's always exciting to see something

530
00:25:08,320 --> 00:25:10,520
Speaker 1: nobody's ever seen before because you don't know what's going

531
00:25:10,600 --> 00:25:12,640
Speaker 1: to be there. Right. Maybe it's like a crashed alien

532
00:25:12,720 --> 00:25:16,800
Speaker 1: battleship or some weird new geological formation. Right, your imagination

533
00:25:17,000 --> 00:25:19,359
Speaker 1: goes crazy when you're first landing on a spot and

534
00:25:19,400 --> 00:25:22,520
Speaker 1: seeing something no human has ever seen before. But you know,

535
00:25:22,680 --> 00:25:26,239
Speaker 1: in research, discoveries never guaranteed. Just because you land on

536
00:25:26,280 --> 00:25:29,240
Speaker 1: new shores doesn't mean you find something fascinating. And in

537
00:25:29,280 --> 00:25:31,440
Speaker 1: this case, basically we found that the far side of

538
00:25:31,440 --> 00:25:34,040
Speaker 1: the Moon has more rocks and more dust, and it's

539
00:25:34,080 --> 00:25:36,640
Speaker 1: not even very different from the front side of the Moon.

540
00:25:36,680 --> 00:25:39,080
Speaker 1: I mean there are more craters, there are fewer of

541
00:25:39,080 --> 00:25:42,800
Speaker 1: these like seas, these lunar lava flows, but all in all,

542
00:25:42,840 --> 00:25:43,960
Speaker 1: it's not that exciting.

543
00:25:44,280 --> 00:25:48,960
Speaker 4: Yeah, that's the moon, good old, dependable.

544
00:25:48,400 --> 00:25:51,159
Speaker 1: Moon, And the first time anybody actually landed there was

545
00:25:51,400 --> 00:25:55,080
Speaker 1: twenty nineteen, like just a few years ago the Chinese

546
00:25:55,080 --> 00:25:57,120
Speaker 1: put a lander down and started to do a bunch

547
00:25:57,119 --> 00:26:00,760
Speaker 1: of experiments. So it's only recently we started to in detail.

548
00:26:00,800 --> 00:26:03,080
Speaker 1: So you know, there's still hope to find that crashed

549
00:26:03,080 --> 00:26:04,480
Speaker 1: alien battleship.

550
00:26:04,200 --> 00:26:07,119
Speaker 4: Or the aliens might be living in a lavatude. We

551
00:26:07,119 --> 00:26:09,760
Speaker 4: could find something even more exciting than what you've imagined.

552
00:26:09,920 --> 00:26:12,760
Speaker 1: Yeah, maybe so, or maybe we could build something that

553
00:26:12,840 --> 00:26:16,000
Speaker 1: future aliens could land and discover for themselves, Like people

554
00:26:16,080 --> 00:26:20,399
Speaker 1: are proposing building radio telescopes on the far side of

555
00:26:20,440 --> 00:26:23,919
Speaker 1: the moon looking out into space, because then you'd have

556
00:26:23,960 --> 00:26:26,560
Speaker 1: the whole moon to shield you from the noise of

557
00:26:26,600 --> 00:26:27,080
Speaker 1: the Earth.

558
00:26:27,280 --> 00:26:31,199
Speaker 4: From my perspective, that's an interesting prospect geopolitically, because if

559
00:26:31,200 --> 00:26:33,520
Speaker 4: you built one of those radio telescopes, it wouldn't work

560
00:26:33,520 --> 00:26:35,880
Speaker 4: as well if people put other stuff on that side

561
00:26:35,880 --> 00:26:39,800
Speaker 4: of the moon. So now there's like competition for that space.

562
00:26:39,920 --> 00:26:42,000
Speaker 4: And can you tell someone they can't use the far

563
00:26:42,080 --> 00:26:44,840
Speaker 4: side of the moon because your radio telescope is there. Anyway,

564
00:26:44,920 --> 00:26:46,760
Speaker 4: these things are complicated, but yes, it would be a

565
00:26:46,800 --> 00:26:48,200
Speaker 4: good place for a radio telescope.

566
00:26:48,320 --> 00:26:50,000
Speaker 1: Sounds like the kind of things a bunch of lawyers

567
00:26:50,000 --> 00:26:51,800
Speaker 1: and a conference room are going to hash out one day.

568
00:26:52,040 --> 00:26:53,439
Speaker 1: So the far side of the Moon is not that

569
00:26:53,680 --> 00:26:56,560
Speaker 1: exciting on its own, but it is fascinating to understand

570
00:26:56,640 --> 00:26:59,080
Speaker 1: why there is a far side of the moon. Before

571
00:26:59,080 --> 00:27:01,000
Speaker 1: we dig into that, I just want to clarify something

572
00:27:01,040 --> 00:27:04,320
Speaker 1: that's a common misunderstanding, which is the difference between the

573
00:27:04,359 --> 00:27:06,639
Speaker 1: far side of the Moon and the dark side of

574
00:27:06,680 --> 00:27:08,879
Speaker 1: the moon. Also, the Pink Floyd.

575
00:27:08,480 --> 00:27:11,000
Speaker 4: Album I don't think anyone needs clarification. We all know

576
00:27:11,080 --> 00:27:14,440
Speaker 4: about that, and we've all probably seen the light show

577
00:27:14,520 --> 00:27:16,240
Speaker 4: if we're around forty years old.

578
00:27:17,000 --> 00:27:19,199
Speaker 1: So some people imagine that the far side of the

579
00:27:19,200 --> 00:27:21,320
Speaker 1: moon is also the dark side of the moon, that like,

580
00:27:21,600 --> 00:27:24,199
Speaker 1: this part of the moon never sees sunlight, which is

581
00:27:24,200 --> 00:27:26,720
Speaker 1: definitely not true. The dark side of the moon is

582
00:27:26,760 --> 00:27:29,040
Speaker 1: the side of the moon facing away from the Sun.

583
00:27:29,320 --> 00:27:31,200
Speaker 1: The far side of the moon is the side facing

584
00:27:31,200 --> 00:27:34,160
Speaker 1: away from the Earth, and those two often don't agree.

585
00:27:34,640 --> 00:27:36,200
Speaker 1: So when we have a full moon, the sun is

586
00:27:36,240 --> 00:27:39,320
Speaker 1: illuminating the entire side of the moon that we are

587
00:27:39,400 --> 00:27:43,040
Speaker 1: seeing because the Sun is sort of behind us in space.

588
00:27:43,280 --> 00:27:45,120
Speaker 1: Then the back side of the moon, the far side

589
00:27:45,119 --> 00:27:48,040
Speaker 1: that we don't see, is also dark. But the opposite

590
00:27:48,080 --> 00:27:50,800
Speaker 1: scenario when the moon is totally dark when we see

591
00:27:50,800 --> 00:27:53,280
Speaker 1: a new moon, and that's because the far side of

592
00:27:53,320 --> 00:27:55,520
Speaker 1: the moon is totally lit up by the sun. Right

593
00:27:55,720 --> 00:27:58,439
Speaker 1: half of the moon is always lit up, it's just

594
00:27:58,480 --> 00:28:01,000
Speaker 1: sometimes not the side of the weird sie, So the

595
00:28:01,040 --> 00:28:03,560
Speaker 1: far side and the dark side are different. It would

596
00:28:03,560 --> 00:28:06,080
Speaker 1: be like a Gary Larsen Pink Floyd crossover event when

597
00:28:06,080 --> 00:28:06,440
Speaker 1: they meet.

598
00:28:06,560 --> 00:28:08,399
Speaker 4: I'm pretty sure if you play dark Side of the

599
00:28:08,400 --> 00:28:12,720
Speaker 4: moon backwards. It explains that.

600
00:28:12,720 --> 00:28:15,320
Speaker 1: That's how you understand the far side cartoons, right, you

601
00:28:15,320 --> 00:28:17,320
Speaker 1: have to listen to the dark side of the moon backwards.

602
00:28:17,400 --> 00:28:20,159
Speaker 4: Yeah, there was a lot of cross talk between the

603
00:28:20,320 --> 00:28:24,879
Speaker 4: arts back then. Okay, so how is this happening? The

604
00:28:25,200 --> 00:28:28,080
Speaker 4: moon was going faster, you said, and it's been slowing down.

605
00:28:29,040 --> 00:28:32,119
Speaker 4: Why has it slowed down to be exactly the same

606
00:28:32,320 --> 00:28:34,439
Speaker 4: rotation rate and stuff? What's going on?

607
00:28:34,600 --> 00:28:37,560
Speaker 1: So it's not a coincidence, right. Physics seems to like

608
00:28:37,640 --> 00:28:41,560
Speaker 1: this scenario, and it's called tidal locking because it's connected

609
00:28:41,600 --> 00:28:44,640
Speaker 1: to the concept of tidal forces, which are in effect

610
00:28:44,640 --> 00:28:47,080
Speaker 1: we see all the time in gravity. And it sounds complicated,

611
00:28:47,120 --> 00:28:49,200
Speaker 1: but it's really pretty simple. The only thing you really

612
00:28:49,240 --> 00:28:53,200
Speaker 1: have to understand is that gravity gets weaker as distances

613
00:28:53,280 --> 00:28:55,200
Speaker 1: get longer. So if you're further away from the Sun,

614
00:28:55,240 --> 00:28:57,520
Speaker 1: it's gravity is less powerful. As you get closer to

615
00:28:57,560 --> 00:29:00,280
Speaker 1: the Sun, it's gravity is more powerful. That makes sense.

616
00:29:00,640 --> 00:29:03,440
Speaker 1: But now imagine you're a pretty big object. So part

617
00:29:03,440 --> 00:29:05,920
Speaker 1: of you is closer to the Sun than another part,

618
00:29:06,200 --> 00:29:09,080
Speaker 1: then part of you is going to feel stronger gravity

619
00:29:09,120 --> 00:29:11,200
Speaker 1: than the other part. And this happens all the time.

620
00:29:11,240 --> 00:29:13,440
Speaker 1: Like if you are standing on the surface of the Earth,

621
00:29:13,760 --> 00:29:16,640
Speaker 1: then the Earth is pulling on your legs harder than

622
00:29:16,640 --> 00:29:19,240
Speaker 1: it's pulling on your head, right, and so that's a

623
00:29:19,280 --> 00:29:22,920
Speaker 1: tidal force. Because there's a difference there. You can actually

624
00:29:22,920 --> 00:29:24,680
Speaker 1: think about the earth as sort of like trying to

625
00:29:24,720 --> 00:29:26,520
Speaker 1: pull your head off of your body.

626
00:29:26,760 --> 00:29:29,960
Speaker 4: Is this like many spaghetification.

627
00:29:29,440 --> 00:29:33,120
Speaker 1: Yes, exactly, when it's very powerful. When it's more powerful,

628
00:29:33,360 --> 00:29:36,600
Speaker 1: then the force is holding an object together, that's spaghetification.

629
00:29:36,760 --> 00:29:39,320
Speaker 1: And so when you get near a black hole, for example,

630
00:29:39,360 --> 00:29:42,680
Speaker 1: gravity is super powerful, and the difference between the gravity

631
00:29:42,720 --> 00:29:45,720
Speaker 1: at your feet and your head is much more dramatic

632
00:29:45,960 --> 00:29:48,160
Speaker 1: and much more powerful than the force is holding your

633
00:29:48,200 --> 00:29:51,000
Speaker 1: head on your body, and so it's effectively natural decapitation

634
00:29:51,400 --> 00:29:52,360
Speaker 1: or spaghetification.

635
00:29:52,720 --> 00:29:56,120
Speaker 4: But lucky for us, instead of death, we get.

636
00:29:55,920 --> 00:29:59,400
Speaker 1: The tie exactly, so you don't have to worry about

637
00:29:59,440 --> 00:30:01,720
Speaker 1: that because it difference of the force of gravity on

638
00:30:01,760 --> 00:30:03,640
Speaker 1: your feet and on your head is very very gentle,

639
00:30:03,880 --> 00:30:06,920
Speaker 1: and your neck is very powerful in comparison. But the

640
00:30:06,920 --> 00:30:09,840
Speaker 1: moon is pretty big, and so the difference between the

641
00:30:09,840 --> 00:30:12,320
Speaker 1: gravitational force on one side of the moon and on the

642
00:30:12,360 --> 00:30:15,640
Speaker 1: other is much stronger. And so what happens is that

643
00:30:15,680 --> 00:30:18,400
Speaker 1: the Earth basically turns the Moon a little bit into

644
00:30:18,400 --> 00:30:21,600
Speaker 1: a football. It like makes it a little bit all blong,

645
00:30:21,640 --> 00:30:23,960
Speaker 1: because it pulls on the closer bits more powerfully, and

646
00:30:24,000 --> 00:30:26,320
Speaker 1: it pulls on the further bits more gently and has

647
00:30:26,360 --> 00:30:28,840
Speaker 1: the effect of sort of like stretching it out, making

648
00:30:28,880 --> 00:30:31,560
Speaker 1: it longer like a football instead of like a sphere.

649
00:30:31,840 --> 00:30:33,480
Speaker 4: This is another one of those things I'm surprised we

650
00:30:33,480 --> 00:30:35,160
Speaker 4: ever figured out, because when I look at the Moon,

651
00:30:35,200 --> 00:30:37,040
Speaker 4: I would not think football.

652
00:30:37,240 --> 00:30:39,400
Speaker 1: It's a subtle effect, right, It looks like a sphere,

653
00:30:39,400 --> 00:30:42,040
Speaker 1: but is slightly distorted by the gravity of the Earth,

654
00:30:42,160 --> 00:30:44,480
Speaker 1: and that has a big impact on how it spins,

655
00:30:44,560 --> 00:30:47,640
Speaker 1: because now it has a gravitational preference to be aligned

656
00:30:47,680 --> 00:30:50,160
Speaker 1: a certain way with the Earth. If it was a

657
00:30:50,200 --> 00:30:53,000
Speaker 1: perfect sphere, then the gravity on the object wouldn't change

658
00:30:53,040 --> 00:30:55,880
Speaker 1: as it spins. But if it has a bulge, then

659
00:30:55,920 --> 00:30:59,840
Speaker 1: gravity prefers that bulge to be aligned with the object.

660
00:31:00,160 --> 00:31:02,880
Speaker 1: Gravity has a handle now on the Moon, and it

661
00:31:03,000 --> 00:31:05,800
Speaker 1: likes to pull that bulge, so one point is towards

662
00:31:05,840 --> 00:31:07,800
Speaker 1: the Earth and one point is away from the Earth.

663
00:31:07,880 --> 00:31:11,960
Speaker 1: That's like gravitationally less energetic a configuration than having the

664
00:31:12,000 --> 00:31:12,760
Speaker 1: whole thing spin.

665
00:31:13,440 --> 00:31:15,080
Speaker 4: All right, Okay, so I'm trying to wrap my head

666
00:31:15,120 --> 00:31:18,520
Speaker 4: around this, and picturing things in my head is not

667
00:31:18,640 --> 00:31:20,560
Speaker 4: one of my stronger suits. But here we go. Okay,

668
00:31:20,560 --> 00:31:22,400
Speaker 4: so we prefer to have a grip on the handle.

669
00:31:22,760 --> 00:31:27,000
Speaker 4: Does the moon spin at a not constant speed where

670
00:31:27,040 --> 00:31:29,120
Speaker 4: like we hold on to the handle for a little longer.

671
00:31:29,360 --> 00:31:31,400
Speaker 4: I don't think that's what you're saying, And so what

672
00:31:31,440 --> 00:31:32,080
Speaker 4: am I missing?

673
00:31:32,280 --> 00:31:34,800
Speaker 1: So what happened initially is that the Earth started to

674
00:31:34,800 --> 00:31:37,800
Speaker 1: form these bulges on the Moon, and then the Moon

675
00:31:37,880 --> 00:31:40,560
Speaker 1: was spinning, and so these bulges were like ripples through

676
00:31:40,600 --> 00:31:43,480
Speaker 1: the surface of the Moon. There were like these waves

677
00:31:43,520 --> 00:31:46,400
Speaker 1: that pass through the Moon. But Earth is also pulling

678
00:31:46,440 --> 00:31:49,480
Speaker 1: on those bulges, right Like, if the Moon has a bulge,

679
00:31:49,480 --> 00:31:51,520
Speaker 1: it's like a football, and then it starts to spin

680
00:31:51,600 --> 00:31:54,080
Speaker 1: away from the Earth. The Earth is going to pull

681
00:31:54,360 --> 00:31:56,720
Speaker 1: on that nearest point a little bit and try to

682
00:31:56,760 --> 00:31:59,480
Speaker 1: pull it back, and that effectively moves the bulge through

683
00:31:59,480 --> 00:32:01,400
Speaker 1: the surface of the Moon a little bit, and so

684
00:32:01,480 --> 00:32:04,200
Speaker 1: that slows down the rotation of the Moon a little

685
00:32:04,200 --> 00:32:06,240
Speaker 1: bit because the Earth is like tugging trying to pull

686
00:32:06,280 --> 00:32:09,280
Speaker 1: that point back towards it, And so that slows the

687
00:32:09,320 --> 00:32:12,600
Speaker 1: Moon down a little bit, and eventually the Moon settles

688
00:32:12,640 --> 00:32:16,160
Speaker 1: into a pattern where these waves the bulge doesn't travel

689
00:32:16,200 --> 00:32:20,080
Speaker 1: over its surface anymore, like settles into one location. And

690
00:32:20,120 --> 00:32:22,080
Speaker 1: that's what the Earth prefers gravitationally.

691
00:32:22,280 --> 00:32:23,720
Speaker 4: Okay, I'm with you, And so.

692
00:32:23,720 --> 00:32:27,000
Speaker 1: That's how gravity makes the Moon a little bit pointy

693
00:32:27,080 --> 00:32:30,600
Speaker 1: and also slows down its spin. It's like stealing some

694
00:32:30,760 --> 00:32:34,000
Speaker 1: of its energy a little bit to slow down its spin.

695
00:32:34,280 --> 00:32:37,880
Speaker 4: But why does its spin get slowed down to exactly

696
00:32:38,080 --> 00:32:40,720
Speaker 4: the right amount, Like it seems like that should just

697
00:32:40,760 --> 00:32:42,120
Speaker 4: slow things down in general.

698
00:32:42,440 --> 00:32:44,800
Speaker 1: It does. It slows things down in general, but at

699
00:32:44,840 --> 00:32:47,160
Speaker 1: some point it starts spinning at just the right speed

700
00:32:47,240 --> 00:32:50,120
Speaker 1: so that the pointy bit is always pointing towards the Earth.

701
00:32:50,520 --> 00:32:52,720
Speaker 1: And then the Earth is happy, and the gravity of

702
00:32:52,720 --> 00:32:55,160
Speaker 1: the Earth no longer wants to slow down the spin

703
00:32:55,320 --> 00:32:57,240
Speaker 1: of the Moon because the point of bit is always

704
00:32:57,280 --> 00:32:59,680
Speaker 1: facing the Earth, and so gravity is happy because it's

705
00:32:59,680 --> 00:33:02,120
Speaker 1: sort of like a ball rolling to the bottom of

706
00:33:02,160 --> 00:33:05,000
Speaker 1: a valley. It's happy when it's settled in the bottom

707
00:33:05,040 --> 00:33:06,840
Speaker 1: of the valley. So this is sort of like, you know,

708
00:33:06,880 --> 00:33:08,440
Speaker 1: you let a marble go at the top of a

709
00:33:08,520 --> 00:33:10,719
Speaker 1: hill and it's going to roll down. It's gonna awesantly

710
00:33:10,840 --> 00:33:13,720
Speaker 1: pass the minimum, but eventually friction and everything, it's gonna

711
00:33:13,760 --> 00:33:16,080
Speaker 1: settle down in the minimum, And the same thing happens.

712
00:33:16,240 --> 00:33:19,280
Speaker 1: There's like friction inside the Moon, and the Moon gets

713
00:33:19,320 --> 00:33:21,440
Speaker 1: heated up a little bit by this, and the Moon

714
00:33:21,600 --> 00:33:24,880
Speaker 1: also speeds up in its orbit because there's like conservation

715
00:33:24,920 --> 00:33:27,720
Speaker 1: of angular momentum. So you've slowed down the Moon's spin

716
00:33:27,760 --> 00:33:29,840
Speaker 1: a little bit and you've sped up its orbit a

717
00:33:29,840 --> 00:33:32,200
Speaker 1: little bit, which is why the Moon's orbital radius is

718
00:33:32,240 --> 00:33:33,360
Speaker 1: increasing a little bit.

719
00:33:33,720 --> 00:33:36,920
Speaker 4: And so how rare is this? Like if Earth were

720
00:33:36,960 --> 00:33:40,600
Speaker 4: a little bit smaller, would this not happen? If there was,

721
00:33:40,720 --> 00:33:43,960
Speaker 4: like if Mars was a little closer, would this not happen?

722
00:33:44,080 --> 00:33:44,160
Speaker 7: Like?

723
00:33:44,320 --> 00:33:46,680
Speaker 4: How lucky are we that it worked out this way?

724
00:33:46,840 --> 00:33:48,880
Speaker 1: We're not that lucky. It's sort of the eventual fate

725
00:33:48,960 --> 00:33:52,200
Speaker 1: of almost every pair of bodies that orbit each other

726
00:33:52,240 --> 00:33:54,480
Speaker 1: for long enough. And in fact, we've done it to

727
00:33:54,520 --> 00:33:57,719
Speaker 1: the Moon, and eventually the Moon will do it to

728
00:33:57,760 --> 00:33:59,960
Speaker 1: the Earth. It's just a slower process.

729
00:34:00,360 --> 00:34:03,880
Speaker 4: Whoa like, how slow like are we gonna be swallowed

730
00:34:03,920 --> 00:34:06,480
Speaker 4: up by the Sun before it happens? Or is my

731
00:34:06,960 --> 00:34:09,960
Speaker 4: you know, kid gonna see it before they turn eighty.

732
00:34:10,320 --> 00:34:14,160
Speaker 1: Yeah, So the Earth's rotation has already been significantly slowed

733
00:34:14,200 --> 00:34:17,200
Speaker 1: by this effect from the Moon. Over the four million

734
00:34:17,280 --> 00:34:19,360
Speaker 1: years since the Earth and the Moon were formed, the

735
00:34:19,480 --> 00:34:22,960
Speaker 1: length of an Earth day has lengthened from six hours

736
00:34:23,120 --> 00:34:26,000
Speaker 1: to twenty four hours. So the Moon has made our

737
00:34:26,080 --> 00:34:29,040
Speaker 1: days four times longer. It's slowed down the Earth spin

738
00:34:29,200 --> 00:34:32,800
Speaker 1: by a big factor. And eventually, because the Moon keeps

739
00:34:32,840 --> 00:34:34,759
Speaker 1: tugging on the Earth and making it a little bit

740
00:34:34,760 --> 00:34:37,920
Speaker 1: longer than tugging on that handle as it passes, eventually

741
00:34:38,000 --> 00:34:41,680
Speaker 1: it's gonna make the Earth take forty seven days to spin.

742
00:34:42,160 --> 00:34:44,120
Speaker 1: And at that point, the Earth and the Moon will

743
00:34:44,160 --> 00:34:47,439
Speaker 1: both be tidally locked to each other, and the Moon

744
00:34:47,520 --> 00:34:50,280
Speaker 1: will only ever see the same face of the Earth.

745
00:34:50,600 --> 00:34:53,880
Speaker 4: I don't think that's very nice of the bit. I

746
00:34:54,080 --> 00:34:57,439
Speaker 4: like having days, ah, so I'm glad that's not gonna

747
00:34:57,440 --> 00:34:58,520
Speaker 4: happen in my lifetime.

748
00:34:58,719 --> 00:35:01,239
Speaker 1: That'd be fascinating, right, because it would mean that half

749
00:35:01,280 --> 00:35:03,000
Speaker 1: of the Earth would see the Moon and the other

750
00:35:03,080 --> 00:35:05,400
Speaker 1: half would never see it. If life of alt in

751
00:35:05,440 --> 00:35:07,440
Speaker 1: that planet, then like half of life wouldn't even know

752
00:35:07,560 --> 00:35:08,399
Speaker 1: there was a moon.

753
00:35:08,880 --> 00:35:10,960
Speaker 4: WHOA I bet we'd have all sorts of different like

754
00:35:11,040 --> 00:35:13,839
Speaker 4: creation stories. If some of us had moons and some

755
00:35:13,880 --> 00:35:16,759
Speaker 4: of us didn't, that would be that would be fascinating.

756
00:35:16,920 --> 00:35:19,279
Speaker 1: Or imagine being an explorer and like settling around the

757
00:35:19,280 --> 00:35:21,960
Speaker 1: world and then discovering this huge thing floating in your sky.

758
00:35:22,080 --> 00:35:27,480
Speaker 1: You're like, what, that would be crazy, that would be

759
00:35:27,560 --> 00:35:29,719
Speaker 1: super amazing. But you're right, it's going to take a

760
00:35:29,760 --> 00:35:33,120
Speaker 1: long time. And well before that happens, the Earth is

761
00:35:33,160 --> 00:35:35,440
Speaker 1: going to be eaten by the Sun, which is going

762
00:35:35,520 --> 00:35:37,960
Speaker 1: to end its life cycle in about five billion years,

763
00:35:38,200 --> 00:35:41,239
Speaker 1: turn into a red giant and absorb the Earth. So

764
00:35:41,400 --> 00:35:44,080
Speaker 1: the moon is not powerful enough to make that happen

765
00:35:44,120 --> 00:35:44,919
Speaker 1: anytime soon.

766
00:35:45,239 --> 00:35:48,520
Speaker 4: Well, on the upbeat topic of the end of our planets,

767
00:35:49,000 --> 00:35:51,319
Speaker 4: let's take a break, and when we come back, you

768
00:35:51,360 --> 00:35:53,719
Speaker 4: can tell us if the other moons on the other

769
00:35:53,800 --> 00:35:55,759
Speaker 4: planets are doing this as well. If I live on

770
00:35:55,840 --> 00:35:58,719
Speaker 4: mars Am, I going to see all of Phobos or not.

771
00:36:03,239 --> 00:36:05,040
Speaker 1: When you pop a piece of cheese into your mouth

772
00:36:05,160 --> 00:36:08,280
Speaker 1: or enjoy a rich spoonful of Greek yogurt, you're probably

773
00:36:08,360 --> 00:36:12,400
Speaker 1: not thinking about the environmental impact of each and every bite.

774
00:36:12,440 --> 00:36:15,040
Speaker 1: But the people in the dairy industry are us Dairy

775
00:36:15,080 --> 00:36:19,360
Speaker 1: has set themselves some ambitious sustainability goals, including being greenhouse

776
00:36:19,400 --> 00:36:22,000
Speaker 1: gas neutral by twenty to fifty. That's why they're working

777
00:36:22,000 --> 00:36:24,360
Speaker 1: hard every day to find new ways to reduce waste,

778
00:36:24,400 --> 00:36:28,640
Speaker 1: conserve natural resources, and drive down greenhouse gas emissions. Take water,

779
00:36:28,680 --> 00:36:31,759
Speaker 1: for example, most dairy farms reuse water up to four

780
00:36:31,840 --> 00:36:35,279
Speaker 1: times the same water cools the milk, cleans equipment, washes

781
00:36:35,320 --> 00:36:38,120
Speaker 1: the barn, and irrigates the crops. How is US dairy

782
00:36:38,160 --> 00:36:41,919
Speaker 1: tackling greenhouse gases? Many farms use anaerobic digestors that turn

783
00:36:41,960 --> 00:36:45,880
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784
00:36:45,880 --> 00:36:47,960
Speaker 1: and electric cars. So the next time you grab a

785
00:36:48,000 --> 00:36:50,000
Speaker 1: slice of pizza or lick an ice cream cone, know

786
00:36:50,080 --> 00:36:52,759
Speaker 1: that dairy farmers and processors around the country are using

787
00:36:52,800 --> 00:36:56,279
Speaker 1: the latest practices and innovations to provide the nutrient dense

788
00:36:56,400 --> 00:36:59,120
Speaker 1: dairy products we love with less of an impact. Visit

789
00:36:59,200 --> 00:37:02,000
Speaker 1: us dairy dot com slash sustainability to learn more.

790
00:37:03,040 --> 00:37:06,520
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791
00:37:06,520 --> 00:37:09,000
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792
00:37:09,000 --> 00:37:11,200
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793
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794
00:37:14,800 --> 00:37:17,120
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795
00:37:17,280 --> 00:37:19,840
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796
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Speaker 3: we are far more active.

797
00:37:21,040 --> 00:37:22,400
Speaker 1: Than we've ever been anywhere else.

798
00:37:22,239 --> 00:37:22,920
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799
00:37:23,560 --> 00:37:26,600
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800
00:37:26,600 --> 00:37:29,840
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801
00:37:29,920 --> 00:37:30,840
Speaker 8: know Minnesota's have.

802
00:37:31,160 --> 00:37:35,480
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803
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804
00:37:38,680 --> 00:37:41,200
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805
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806
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807
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808
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809
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810
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811
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812
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813
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814
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815
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816
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817
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818
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819
00:38:42,960 --> 00:38:46,840
Speaker 4: Okay, we're back. So, Daniel, the question that everybody wants

820
00:38:46,880 --> 00:38:50,080
Speaker 4: to know when we move to Mars, are we going

821
00:38:50,120 --> 00:38:53,040
Speaker 4: to see the far side of Phobos and Deimos or what?

822
00:38:53,360 --> 00:38:55,360
Speaker 1: So this is a process that happens all over the

823
00:38:55,360 --> 00:38:59,160
Speaker 1: Solar System and all over the universe. Eventually, gravity will

824
00:38:59,160 --> 00:39:02,080
Speaker 1: do its bit and dis door objects from spheres into

825
00:39:02,120 --> 00:39:05,160
Speaker 1: like gentle little footballs. It'll grab on those handles and

826
00:39:05,200 --> 00:39:07,799
Speaker 1: it will hidly lock stuff. And so as we look

827
00:39:07,800 --> 00:39:10,120
Speaker 1: around the Solar System, we notice that all of the

828
00:39:10,160 --> 00:39:13,800
Speaker 1: big moons, all of the twenty round moons that exist

829
00:39:13,960 --> 00:39:18,000
Speaker 1: around planets, are all tidally locked to their planet.

830
00:39:18,400 --> 00:39:21,360
Speaker 4: Only the round moons. And what causes the moon to

831
00:39:21,400 --> 00:39:24,480
Speaker 4: be round, It's that it needs to be a certain size,

832
00:39:24,719 --> 00:39:25,279
Speaker 4: Is that right?

833
00:39:25,480 --> 00:39:27,560
Speaker 1: Yeah, if you're big enough, then gravity is going to

834
00:39:27,560 --> 00:39:30,600
Speaker 1: be powerful enough to pull down any big features, which

835
00:39:30,640 --> 00:39:33,720
Speaker 1: is why, for example, like neutron stars have no features

836
00:39:33,719 --> 00:39:36,000
Speaker 1: on them that are higher than one millimeter, and the

837
00:39:36,120 --> 00:39:38,600
Speaker 1: larger the gravity, the harder it is to keep a

838
00:39:38,640 --> 00:39:41,520
Speaker 1: stack of stuff from falling down. And so if you're

839
00:39:41,520 --> 00:39:43,440
Speaker 1: a pretty small object, you don't have to be very

840
00:39:43,480 --> 00:39:46,040
Speaker 1: spherical because your gravity's pretty weak. If you're a big

841
00:39:46,120 --> 00:39:48,480
Speaker 1: object like the Moon or the Earth, then you're going

842
00:39:48,520 --> 00:39:51,760
Speaker 1: to end up as a sphere because stuff falls down basically,

843
00:39:52,040 --> 00:39:54,640
Speaker 1: and stuff falls down more when you have more gravity.

844
00:39:54,920 --> 00:39:57,960
Speaker 1: And so these round moons are technically not actually round, right,

845
00:39:58,000 --> 00:40:01,120
Speaker 1: they're a little bit footballish and they're all tidally locked

846
00:40:01,400 --> 00:40:04,280
Speaker 1: to their planet. Most of these also orbit pretty closely,

847
00:40:04,360 --> 00:40:06,960
Speaker 1: and so their gravity is pretty powerful. And then example,

848
00:40:07,000 --> 00:40:09,680
Speaker 1: you raised like Phobos and Demos on Mars. These are

849
00:40:09,800 --> 00:40:13,560
Speaker 1: little moons and they're not very large, they're not very round,

850
00:40:13,719 --> 00:40:15,799
Speaker 1: and they're actually spinning really really fast. And so while

851
00:40:15,840 --> 00:40:19,600
Speaker 1: Mars is doing its job to try to tidly lock them, Phobos,

852
00:40:19,600 --> 00:40:22,080
Speaker 1: for example, is not yet tidally.

853
00:40:21,719 --> 00:40:22,799
Speaker 4: Locked, but it will be.

854
00:40:23,000 --> 00:40:25,480
Speaker 1: It will be eventually. It's going to happen to everybody.

855
00:40:25,840 --> 00:40:28,560
Speaker 4: So we've been talking about moon planets. Has it happened

856
00:40:28,560 --> 00:40:32,239
Speaker 4: to any sun and planets or planets yet?

857
00:40:32,520 --> 00:40:35,120
Speaker 1: Absolutely it has, and absolutely it will. Right the Sun

858
00:40:35,200 --> 00:40:37,560
Speaker 1: is the most powerful source of gravity in the Solar System,

859
00:40:37,600 --> 00:40:39,360
Speaker 1: and so it's not going to be left out of

860
00:40:39,440 --> 00:40:43,400
Speaker 1: this party. And it has mercury tidly locked in its grasp.

861
00:40:43,600 --> 00:40:46,879
Speaker 1: But it's actually fascinating. It's not quite the same way

862
00:40:47,400 --> 00:40:50,360
Speaker 1: as with the Earth and the Moon because mercury doesn't

863
00:40:50,400 --> 00:40:53,600
Speaker 1: have as circular an orbit. It's much more elliptical. The

864
00:40:53,760 --> 00:40:56,640
Speaker 1: mercury is tidly locked in this weird way. Instead of

865
00:40:56,920 --> 00:41:00,080
Speaker 1: spinning once every time it goes around the sun's me

866
00:41:00,280 --> 00:41:03,600
Speaker 1: three times for every two revolutions around the Sun. And

867
00:41:03,640 --> 00:41:06,360
Speaker 1: this is not something we understood for a while because

868
00:41:06,400 --> 00:41:08,719
Speaker 1: we can't always see mercury because it's so close to

869
00:41:08,719 --> 00:41:11,560
Speaker 1: the Sun. There's a few spots in its orbit when

870
00:41:11,560 --> 00:41:13,879
Speaker 1: it's like easy to see mercury, and so when people

871
00:41:13,880 --> 00:41:16,839
Speaker 1: were observing mercury, they were always seeing the same side

872
00:41:16,840 --> 00:41:18,279
Speaker 1: of it. So they thought, oh, it must have been

873
00:41:18,280 --> 00:41:20,680
Speaker 1: a one to one tidle locking. And it's only later

874
00:41:20,719 --> 00:41:23,440
Speaker 1: when we got more observations in mercury did we notice, oh, no,

875
00:41:23,520 --> 00:41:26,479
Speaker 1: it's doing this even weirder thing. That's because the orbit

876
00:41:26,560 --> 00:41:29,000
Speaker 1: is not circular and so it can do another little

877
00:41:29,000 --> 00:41:31,239
Speaker 1: bit of spin as it gets further away and then

878
00:41:31,280 --> 00:41:34,200
Speaker 1: it comes back around, but still it settles into this

879
00:41:34,320 --> 00:41:37,320
Speaker 1: really cool pattern, this three two tidal locking.

880
00:41:37,440 --> 00:41:40,080
Speaker 4: All right, So let's see, my very elderly mother were

881
00:41:40,080 --> 00:41:44,040
Speaker 4: on V I'm guessing Mercury is tidally locked in part

882
00:41:44,080 --> 00:41:47,200
Speaker 4: because it's so close to the sun. So is Venus

883
00:41:47,400 --> 00:41:50,600
Speaker 4: the next closest to being tidally locked or is it

884
00:41:50,680 --> 00:41:51,480
Speaker 4: tidally locked?

885
00:41:51,520 --> 00:41:55,200
Speaker 1: Also, Venus is next on the list to getting tightly locked.

886
00:41:55,400 --> 00:41:58,080
Speaker 1: It's not yet tidly locked. In fact, Venus has a

887
00:41:58,160 --> 00:42:02,080
Speaker 1: really weird orbit ends. It takes five hundred and eighty

888
00:42:02,200 --> 00:42:04,960
Speaker 1: three days to go around the Sun, but it takes

889
00:42:05,000 --> 00:42:08,839
Speaker 1: two hundred and twenty four Earth days to rotate, So

890
00:42:08,960 --> 00:42:13,360
Speaker 1: like a Venus year only has one point nine Venus days.

891
00:42:14,080 --> 00:42:17,400
Speaker 1: Like you only see two sunrises and two sunsets in

892
00:42:17,440 --> 00:42:18,239
Speaker 1: a Venus year.

893
00:42:18,600 --> 00:42:20,960
Speaker 4: Huh, But that wouldn't bother you, because Venus would have

894
00:42:21,040 --> 00:42:24,520
Speaker 4: killed you in four or five different ways, long before

895
00:42:24,560 --> 00:42:26,440
Speaker 4: you cared about whether the sunrise was coming.

896
00:42:27,480 --> 00:42:29,640
Speaker 1: That's right. But Venus is sot again there right, Like

897
00:42:29,680 --> 00:42:33,480
Speaker 1: its spin is similar to its orbital period. We actually

898
00:42:33,480 --> 00:42:36,040
Speaker 1: think that's because of a collision that Venus was like

899
00:42:36,160 --> 00:42:39,120
Speaker 1: smacked in du By something which really changed its spin.

900
00:42:39,400 --> 00:42:41,000
Speaker 1: We don't think there's been enough time for it to

901
00:42:41,000 --> 00:42:43,600
Speaker 1: be like almost highly locked by the Sun. It takes

902
00:42:43,600 --> 00:42:45,919
Speaker 1: a much longer time because Venus is so far away

903
00:42:45,920 --> 00:42:48,880
Speaker 1: from the Sun and so small relative to the Sun.

904
00:42:49,080 --> 00:42:54,560
Speaker 4: All right, so we've done moon and planets. We've done

905
00:42:54,600 --> 00:43:00,240
Speaker 4: comparisons between the Sun and the planets. Is there any

906
00:43:00,440 --> 00:43:04,120
Speaker 4: other combination of tidally locked things for us to think about?

907
00:43:04,160 --> 00:43:06,680
Speaker 4: Can asteroids get tidally locked? For example?

908
00:43:06,960 --> 00:43:09,560
Speaker 1: They could, but it's much harder because their gravity is

909
00:43:09,560 --> 00:43:12,480
Speaker 1: so weak. Another really fascinating thing to look at are

910
00:43:12,600 --> 00:43:17,400
Speaker 1: things that have similar masses, like dwarf planets and their moons. So,

911
00:43:17,520 --> 00:43:20,640
Speaker 1: for example, Pluto no longer a planet, but it's still

912
00:43:20,640 --> 00:43:24,680
Speaker 1: a dwarf planet. It's got a pretty big moon, Sharon,

913
00:43:25,239 --> 00:43:28,920
Speaker 1: And these two things are mutually tightly locked already. So

914
00:43:28,960 --> 00:43:30,840
Speaker 1: if you're like on Pluto and you look up, you

915
00:43:31,000 --> 00:43:33,880
Speaker 1: always see the same side of the moon. And if

916
00:43:33,880 --> 00:43:36,280
Speaker 1: you're on Pluto's moon and you look up, you always

917
00:43:36,320 --> 00:43:38,080
Speaker 1: see the same side of Pluto.

918
00:43:38,320 --> 00:43:40,359
Speaker 4: Oh, interesting to how many moons does Pluto have?

919
00:43:40,640 --> 00:43:42,680
Speaker 1: Oh, Pluto's got a bunch of moons, but most of

920
00:43:42,680 --> 00:43:46,000
Speaker 1: them rotate chaotically. They're too small to have been tidly

921
00:43:46,040 --> 00:43:48,560
Speaker 1: locked so far. But it's sort of beautiful to see

922
00:43:48,600 --> 00:43:51,160
Speaker 1: these things like orbiting their center of mass and facing

923
00:43:51,160 --> 00:43:52,600
Speaker 1: each other. It's kind of like a dance.

924
00:43:52,920 --> 00:43:55,080
Speaker 4: Yeah, that's awesome. It's beautiful.

925
00:43:55,200 --> 00:43:57,320
Speaker 1: And that's not the only example of a dwarf planet.

926
00:43:57,360 --> 00:44:00,920
Speaker 1: There's another one out there, a trans Neptunian object called Eris,

927
00:44:00,920 --> 00:44:03,200
Speaker 1: which is also a dwarf planet, and it's got a

928
00:44:03,200 --> 00:44:06,480
Speaker 1: pretty big moon called Dyspnomia, which happens to be the

929
00:44:06,560 --> 00:44:11,080
Speaker 1: second largest dwarf planet moon after Pluto's moon, And these

930
00:44:11,080 --> 00:44:13,120
Speaker 1: two are also tidly locked with each other.

931
00:44:13,400 --> 00:44:16,320
Speaker 4: That sounds like it's a pretty common thing for dwarf

932
00:44:16,360 --> 00:44:18,560
Speaker 4: planets to have moons, that know, because how many dwarf

933
00:44:18,560 --> 00:44:19,320
Speaker 4: planets are there.

934
00:44:19,440 --> 00:44:21,319
Speaker 1: There's a lot of dwarf planets out there. That's one

935
00:44:21,440 --> 00:44:24,080
Speaker 1: reason why Pluto isn't really a planet anymore, because we

936
00:44:24,120 --> 00:44:26,440
Speaker 1: discovered there's kind of a lot of them out there.

937
00:44:26,480 --> 00:44:28,120
Speaker 1: And if we call Pluto a planet, we've got to

938
00:44:28,160 --> 00:44:30,360
Speaker 1: call them all planets, and then we're going to have

939
00:44:30,360 --> 00:44:32,440
Speaker 1: a lot of planet and so, you know, astronomers have

940
00:44:32,480 --> 00:44:35,080
Speaker 1: big arguments about where to draw the line, But there's

941
00:44:35,080 --> 00:44:36,359
Speaker 1: a lot of dwarf planets out.

942
00:44:36,280 --> 00:44:38,000
Speaker 4: There, right, and like, how are we going to have

943
00:44:38,080 --> 00:44:40,320
Speaker 4: mnemonic if there's twenty of them or something like we

944
00:44:40,600 --> 00:44:42,839
Speaker 4: just no way, no way, all right. So that's our

945
00:44:42,920 --> 00:44:46,680
Speaker 4: solar system. This sounds like a fundamental physics thing. So

946
00:44:46,719 --> 00:44:49,080
Speaker 4: I'm guessing that when we look at other solar systems,

947
00:44:49,080 --> 00:44:50,319
Speaker 4: they've got the same thing going on.

948
00:44:50,560 --> 00:44:53,680
Speaker 1: Yes, exactly. We expect that the same thing will happen

949
00:44:53,719 --> 00:44:57,560
Speaker 1: to planets around other stars and to moons around those planets.

950
00:44:58,160 --> 00:45:00,080
Speaker 1: And because of sort of the way that we we

951
00:45:00,120 --> 00:45:03,560
Speaker 1: can discover those exoplanets, we expect a lot of the

952
00:45:03,560 --> 00:45:07,239
Speaker 1: ones we've seen so far have been tidly locked. Like

953
00:45:07,280 --> 00:45:10,120
Speaker 1: the way that we discover these planets is by seeing

954
00:45:10,160 --> 00:45:13,240
Speaker 1: their impact on their star. Either they pass in front

955
00:45:13,239 --> 00:45:15,320
Speaker 1: of their stars, so they give like a little mini

956
00:45:15,400 --> 00:45:18,719
Speaker 1: planetary eclipse which dims the star a little bit, or

957
00:45:19,120 --> 00:45:21,640
Speaker 1: they wiggle the star because of the gravity of the

958
00:45:21,680 --> 00:45:24,879
Speaker 1: planet pulling on the star. So in both cases they

959
00:45:24,880 --> 00:45:27,120
Speaker 1: have to be pretty close to the star for us

960
00:45:27,160 --> 00:45:29,320
Speaker 1: to see it, which means that of all the planets

961
00:45:29,320 --> 00:45:32,080
Speaker 1: out there in the galaxy orbiting their stars, we're best

962
00:45:32,120 --> 00:45:34,320
Speaker 1: at seeing the ones that are closest to their stars,

963
00:45:34,520 --> 00:45:37,319
Speaker 1: which also means we're best at seeing the ones that

964
00:45:37,360 --> 00:45:41,200
Speaker 1: are probably tidally locked. And so astronomers have done a

965
00:45:41,200 --> 00:45:43,680
Speaker 1: bunch of calculations to understand the orbits of these things

966
00:45:43,760 --> 00:45:46,759
Speaker 1: and the masses and predict their tidal locking, and they

967
00:45:46,760 --> 00:45:49,560
Speaker 1: expect that a lot of these planets are tidly locked,

968
00:45:49,920 --> 00:45:52,640
Speaker 1: maybe one to one, maybe like three to two the

969
00:45:52,680 --> 00:45:55,680
Speaker 1: way Mercury is, or maybe like five to two. It

970
00:45:55,719 --> 00:45:58,200
Speaker 1: depends a lot on the eccentricity of the orbit, which

971
00:45:58,280 --> 00:46:01,320
Speaker 1: the sort of gravitationally preferred arrangement.

972
00:46:01,520 --> 00:46:03,959
Speaker 4: Would it be fair to say that it's too far

973
00:46:04,120 --> 00:46:06,719
Speaker 4: away for us to have been able outside of our

974
00:46:06,800 --> 00:46:10,680
Speaker 4: Solar system to see planets and their moons being tidally locked,

975
00:46:10,680 --> 00:46:12,000
Speaker 4: and so the only thing we've been able to look

976
00:46:12,040 --> 00:46:15,000
Speaker 4: at so far is tidal locking with suns and planets.

977
00:46:15,160 --> 00:46:18,480
Speaker 1: Yeah, that's exactly right. Exo moons is a brand new

978
00:46:18,640 --> 00:46:21,840
Speaker 1: area of study. People looking for these moons around exo

979
00:46:21,920 --> 00:46:25,040
Speaker 1: planets super exciting, and in the next few years, as

980
00:46:25,080 --> 00:46:27,360
Speaker 1: we turn on more and more space telescopes, we're going

981
00:46:27,440 --> 00:46:30,600
Speaker 1: to get more more information about these planets and their

982
00:46:30,640 --> 00:46:32,880
Speaker 1: moons and we can start to measure their spin and

983
00:46:32,920 --> 00:46:35,319
Speaker 1: to understand this and to figure out like whether these

984
00:46:35,360 --> 00:46:38,040
Speaker 1: planets out there a lot more of them are tidly

985
00:46:38,080 --> 00:46:40,200
Speaker 1: locked or a lot less. You know, a question we

986
00:46:40,320 --> 00:46:44,319
Speaker 1: always have is is our solar system weird or is

987
00:46:44,360 --> 00:46:47,319
Speaker 1: it typical? Like in most cases, is it just the

988
00:46:47,360 --> 00:46:49,600
Speaker 1: first couple of planets closest to the Sun that are

989
00:46:49,600 --> 00:46:52,279
Speaker 1: tidally locked, which would align with our understanding and tell

990
00:46:52,360 --> 00:46:54,680
Speaker 1: us that our solar system's not that weird, or maybe

991
00:46:54,800 --> 00:46:57,160
Speaker 1: would be surprised and we'll discover, oh my gosh, all

992
00:46:57,200 --> 00:46:59,600
Speaker 1: those solar systems out there, they're all tidly locked. What's

993
00:46:59,640 --> 00:47:02,600
Speaker 1: going on? And something is different from what we expect.

994
00:47:02,840 --> 00:47:04,680
Speaker 1: You never know when you go out to the universe

995
00:47:04,719 --> 00:47:06,919
Speaker 1: and ask these questions and look for the first time,

996
00:47:07,080 --> 00:47:09,040
Speaker 1: if you're just going to see like more dust and

997
00:47:09,080 --> 00:47:11,120
Speaker 1: rebbel or something really really exciting.

998
00:47:11,280 --> 00:47:13,840
Speaker 4: The universe is good at providing job security in the

999
00:47:13,880 --> 00:47:15,040
Speaker 4: form of new questions.

1000
00:47:15,160 --> 00:47:17,440
Speaker 1: And it's not just stars and planets we can study.

1001
00:47:17,440 --> 00:47:21,399
Speaker 1: We can also look at pairs of stars. We're used

1002
00:47:21,440 --> 00:47:24,360
Speaker 1: to thinking about stars as like individual and you have

1003
00:47:24,400 --> 00:47:26,840
Speaker 1: a solar system with one star at its core and

1004
00:47:26,880 --> 00:47:30,040
Speaker 1: a bunch of planets, but Actually, there's lots of binary

1005
00:47:30,080 --> 00:47:33,000
Speaker 1: star systems out there, and the reason is that stars

1006
00:47:33,000 --> 00:47:35,320
Speaker 1: when they're formed, it's a big cloud of gas and

1007
00:47:35,400 --> 00:47:38,799
Speaker 1: dust which collapses, and typically you get multiple stars from

1008
00:47:38,840 --> 00:47:41,000
Speaker 1: a big cloud of gas and dust. You have like

1009
00:47:41,080 --> 00:47:45,480
Speaker 1: little gravitational seeds that start this runaway gravitational effect. And

1010
00:47:45,520 --> 00:47:47,080
Speaker 1: you don't just have one seed, you have a bunch

1011
00:47:47,120 --> 00:47:49,640
Speaker 1: of them, so you get like a stellar nursery makes

1012
00:47:49,840 --> 00:47:52,239
Speaker 1: lots and lots of stars. So we have a whole

1013
00:47:52,280 --> 00:47:55,719
Speaker 1: podcast episode about binary star systems and even like trinary

1014
00:47:55,800 --> 00:47:58,200
Speaker 1: star systems. But the point is that lots of stars

1015
00:47:58,320 --> 00:48:01,560
Speaker 1: out there have brothers and sisters they were born with

1016
00:48:01,640 --> 00:48:04,959
Speaker 1: like twins, and so they're pretty close to another star,

1017
00:48:05,280 --> 00:48:07,759
Speaker 1: which means that you can have pairs of stars that

1018
00:48:07,800 --> 00:48:09,680
Speaker 1: are tidly locked to each other.

1019
00:48:09,960 --> 00:48:11,080
Speaker 4: That's awesome.

1020
00:48:11,280 --> 00:48:13,520
Speaker 1: Or if you have a really big planet, you could

1021
00:48:13,520 --> 00:48:15,800
Speaker 1: have a planet and a star that are tidly locked

1022
00:48:15,840 --> 00:48:18,319
Speaker 1: to each other, so the planet is always seeing the

1023
00:48:18,320 --> 00:48:21,600
Speaker 1: same side of the star. Right, that could be weird.

1024
00:48:22,000 --> 00:48:24,160
Speaker 4: Yeah, but we haven't seen that yet, Right, we.

1025
00:48:24,160 --> 00:48:26,160
Speaker 1: Have not seen that yet. There's a star out there

1026
00:48:26,200 --> 00:48:30,440
Speaker 1: Tau Buddhists, which we suspect is tidly locked to its planet.

1027
00:48:30,480 --> 00:48:32,520
Speaker 1: But we're not one hundred percent sure of that. But

1028
00:48:32,560 --> 00:48:34,720
Speaker 1: you know, this kind of stuff makes a difference because

1029
00:48:34,719 --> 00:48:37,360
Speaker 1: it really changes the experience of being on a planet.

1030
00:48:37,600 --> 00:48:40,239
Speaker 1: Like if Earth was tidly locked to the sun, we'd

1031
00:48:40,280 --> 00:48:42,480
Speaker 1: have half of the Earth at sunshine all day, and

1032
00:48:42,600 --> 00:48:45,000
Speaker 1: half of the Earth would be the dark side of

1033
00:48:45,000 --> 00:48:46,920
Speaker 1: the Earth. The far side of the Earth would be

1034
00:48:46,960 --> 00:48:49,560
Speaker 1: the dark side, you know where Pink Floyd plays concerts

1035
00:48:49,560 --> 00:48:52,719
Speaker 1: and Gary Larson draws his cartoons, And that would be

1036
00:48:52,760 --> 00:48:54,600
Speaker 1: the very very cold side of.

1037
00:48:54,560 --> 00:48:56,719
Speaker 4: The Earth, right dead side, Yah, the.

1038
00:48:56,719 --> 00:48:59,920
Speaker 1: Dead side exactly. And then you'd have this ring right

1039
00:49:00,080 --> 00:49:01,560
Speaker 1: in the middle of the Earth that was like right

1040
00:49:01,600 --> 00:49:04,640
Speaker 1: on the edge. It'd be like permanent sunrise, and that

1041
00:49:04,760 --> 00:49:07,080
Speaker 1: might be the only place on the planet you could

1042
00:49:07,080 --> 00:49:09,080
Speaker 1: live because one side would be too hot and one

1043
00:49:09,080 --> 00:49:10,680
Speaker 1: side would be too cold. And then you'd have this

1044
00:49:10,800 --> 00:49:14,719
Speaker 1: like Goldilocks ring around the planet that might be hospitable.

1045
00:49:14,880 --> 00:49:19,240
Speaker 4: Location, location, location, exactly.

1046
00:49:19,280 --> 00:49:22,120
Speaker 1: And so if that's the case on some of these exoplanets,

1047
00:49:22,440 --> 00:49:24,959
Speaker 1: that means it'd be a lot harder for life to form.

1048
00:49:25,040 --> 00:49:28,239
Speaker 1: Either they'd have to evolve to survive very hot conditions

1049
00:49:28,360 --> 00:49:31,040
Speaker 1: or very cold conditions, or there'd only be a thin

1050
00:49:31,200 --> 00:49:33,440
Speaker 1: strip of their planet that they could live on, and

1051
00:49:33,480 --> 00:49:35,560
Speaker 1: you know, then there wouldn't be seasons. In the same way,

1052
00:49:35,600 --> 00:49:38,040
Speaker 1: it would make for a very different kind of biology.

1053
00:49:38,360 --> 00:49:41,400
Speaker 4: It would make it easy to study extremophiles, though, because

1054
00:49:41,440 --> 00:49:44,359
Speaker 4: you know exactly where you needed to go, just you know,

1055
00:49:44,440 --> 00:49:46,200
Speaker 4: the cold ones are over there and the hot ones

1056
00:49:46,200 --> 00:49:47,920
Speaker 4: are over there. But there probably wouldn't be a lot

1057
00:49:47,920 --> 00:49:49,400
Speaker 4: of funding for science that are world like that.

1058
00:49:50,560 --> 00:49:53,120
Speaker 1: You never know, right, And we have all these expectations

1059
00:49:53,120 --> 00:49:55,480
Speaker 1: for what life would be like on these planets because

1060
00:49:55,480 --> 00:49:58,160
Speaker 1: we imagine what our life would be like on those planets.

1061
00:49:58,200 --> 00:50:00,120
Speaker 1: But of course if you evolve on those plants and

1062
00:50:00,160 --> 00:50:02,040
Speaker 1: if you think that's the normal way to live, and

1063
00:50:02,080 --> 00:50:05,080
Speaker 1: they would think it's super duper weird for like your

1064
00:50:05,080 --> 00:50:08,920
Speaker 1: planet to spin and get constantly bathed in sunlight, or

1065
00:50:08,960 --> 00:50:11,640
Speaker 1: for you to have no control over whether you're seeing

1066
00:50:11,640 --> 00:50:14,360
Speaker 1: the sun or not, because on tidly locked planets you

1067
00:50:14,360 --> 00:50:16,799
Speaker 1: don't want sun, you just move to the backside. You

1068
00:50:16,840 --> 00:50:18,880
Speaker 1: want sun, you move to the front side, totally up

1069
00:50:18,920 --> 00:50:21,560
Speaker 1: to you, whereas here we're like at the mercy of

1070
00:50:21,600 --> 00:50:25,160
Speaker 1: celestial objects. Spin rates to determine when we see sun

1071
00:50:25,200 --> 00:50:25,600
Speaker 1: and when we.

1072
00:50:25,560 --> 00:50:27,560
Speaker 4: Don't, Yeah, I guess you get used to what you

1073
00:50:27,600 --> 00:50:30,560
Speaker 4: grew up with. It sure seems like it's nice to

1074
00:50:30,640 --> 00:50:32,320
Speaker 4: have a more moderate in between.

1075
00:50:32,680 --> 00:50:35,880
Speaker 1: It certainly does. But in the end, the universe prefers

1076
00:50:35,960 --> 00:50:38,600
Speaker 1: tidal lock, and given enough time gravity, it's going to

1077
00:50:38,680 --> 00:50:41,200
Speaker 1: do its business make everything round and then make it

1078
00:50:41,239 --> 00:50:43,840
Speaker 1: a little bit footballish, and it's going to tug on

1079
00:50:43,920 --> 00:50:48,480
Speaker 1: those gravitational handles until everything is tidly locked, unless, of course,

1080
00:50:48,520 --> 00:50:51,760
Speaker 1: your sun explodes and eat you before it can even happen.

1081
00:50:51,840 --> 00:50:54,440
Speaker 1: But it's sort of the gravitational destiny of every other

1082
00:50:54,520 --> 00:50:55,240
Speaker 1: kind of object.

1083
00:50:55,520 --> 00:50:58,960
Speaker 4: And there's the ending that'll keep my kids from listening.

1084
00:51:00,680 --> 00:51:05,040
Speaker 1: And hopefully inspire a lot of crazy music and silly cartoons. Yes,

1085
00:51:05,880 --> 00:51:08,520
Speaker 1: all right, Thanks very much everybody for exploring the physics

1086
00:51:08,560 --> 00:51:10,960
Speaker 1: of title locking with us. It turns out to play

1087
00:51:11,000 --> 00:51:13,040
Speaker 1: a big role in what it's like to live on

1088
00:51:13,080 --> 00:51:15,120
Speaker 1: our planet, what it's like to look up at disguise

1089
00:51:15,200 --> 00:51:19,200
Speaker 1: and understand the universe or wonder at its mysteries, and

1090
00:51:19,239 --> 00:51:21,520
Speaker 1: it will continue to play a big role in life

1091
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Speaker 1: on Earth. Thanks for listening. Tune in next time. Thanks

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Speaker 1: for listening, and remember that Daniel and Jorge Explain the

1093
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Speaker 1: Universe is a production of iHeart Radio. For more podcasts

1094
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Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

1095
00:51:44,040 --> 00:51:57,239
Speaker 1: you listen to your favorite shows. When you pop a

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Speaker 1: piece of cheese into your mouth, you're probably not thinking

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Speaker 1: industry are. That's why they're working hard every day to

1099
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Speaker 1: find new ways to reduce waste, conserve natural resources, and

1100
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Speaker 1: drive down greenhouse gas emissions. House US dairy tackling greenhouse gases,

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Speaker 1: Many farms use anaerobic digesters to turn the methane from

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Speaker 1: electric cars. Visit you as dairy dot COM's Last Sustainability

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Speaker 1: to learn more.

1105
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Speaker 2: There are children, friends, and families walking, riding on paths

1106
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Speaker 2: and roads every day. Remember they're real people with loved

1107
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Speaker 2: cyclists and pedestrians because they're people too.

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Speaker 1: Go safely.

1110
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Speaker 2: California from the California Office of Traffic Safety and Caltrans.

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Speaker 1: This is Malcolm Gladwell from Revisionist History.

1112
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