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Speaker 1: Hey, Kelly, do you ever wish that our night sky

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Speaker 1: was I don't know, a little bit more dramatic, more dramatic.

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Speaker 1: We've got a huge moon, planets, stars, and all of

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Speaker 1: the Milky Way. You've got pretty high standards for the

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Speaker 1: night sky. What did you have in mind? I don't know.

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Speaker 1: Sometimes I think it's boring to have just that one

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Speaker 1: huge moon. It seems like it might be more exciting

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Speaker 1: to have lots of little moons up there. Okay, all right,

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Speaker 1: that's true. It's kind of like having an only child. Yeah,

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Speaker 1: and not just an only child, like a single mega child.

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Speaker 1: You want drama. What's more dramatic than the Earth's mega

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Speaker 1: child hovering above you in the sky. Yeah, I guess

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Speaker 1: I wanted drama. But now I'm worried that the idea

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Speaker 1: of a mega child is going to give me nightmares. Yeah,

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Speaker 1: me too. I like my two little ones. Hi. I'm Daniel.

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Speaker 1: I'm a particle physicist, and I'm very happy to have

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Speaker 1: too normal sized children instead of one mega child. And

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Speaker 1: I'm Kelly. I'm a parasitologist, and I also have two

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Speaker 1: normal sized children, and that works well for me. You

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Speaker 1: having considered the concept of like combining them together into

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Speaker 1: one child unification of the children. You know, Zach likes

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Speaker 1: to joke that they stack when he stacks them. They

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Speaker 1: don't seem very happy about it, and so you know,

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Speaker 1: I haven't thought too hard about trying to combine them.

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Speaker 1: I don't think they'd be big fans of that. I'm

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Speaker 1: pretty sure my kids wouldn't be into that either. Well,

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Speaker 1: Welcome to the podcast Daniel and Jorge explain the universe

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Speaker 1: and which we ask the hard questions of the universe.

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Speaker 1: We talked about the crazy stuff that's out there deep

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Speaker 1: in the cosmos, and we talked about the tiny little

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Speaker 1: particles that are wriggling around inside my children, your children,

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Speaker 1: and everybody's children. We try to explore the entire universe

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Speaker 1: and explain all of it to you. Normally we have

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Speaker 1: my friend and co host Jorge him here on the podcast,

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Speaker 1: but he's unavailable today, so we have our wonderful, hilarious

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Speaker 1: guest host, Kelly Weener Smith. Hello, I'm excited to be back.

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Speaker 1: Thanks very much for joining us and for talking to

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Speaker 1: us about crazy stuff in the universe. So on the podcast,

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Speaker 1: we sometimes like to dig into stuff that's really complicated,

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Speaker 1: like how does quantum field theory work, and what is

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Speaker 1: the real charge of the electron? Or what is it

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Speaker 1: like to go inside a black hole? These are deep

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Speaker 1: and complicated questions about the universe that we try to

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Speaker 1: take apart and explain to you. But sometimes we also

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Speaker 1: like to dive into simpler seeming in questions, questions that

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Speaker 1: might seem like they have an obvious answer but then

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Speaker 1: have some interesting little wrinkles. It's good to have diversity, yeah,

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Speaker 1: because questions are at the heart of science, and they're

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Speaker 1: not just the questions that scientists ask when they're doing

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Speaker 1: their research, but we're also interested in the questions that

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Speaker 1: everybody asks. And sometimes the best questions are the questions

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Speaker 1: that children ask, the most obvious questions which sometimes have

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Speaker 1: a tricky answer. And I remember looking up at the

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Speaker 1: night sky with my kids, who are now twelve and fourteen,

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Speaker 1: but earlier asked very simple, basic, fun questions about the universe,

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Speaker 1: like why do we only have one moon? Or do

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Speaker 1: we only have one moon? Kelly, what kind of questions

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Speaker 1: do your kids ask when they look at the night sky?

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Speaker 1: I was just trying to think of a good example

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Speaker 1: of Like, my daughter is seven, and she's always asking

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Speaker 1: me questions that I don't know the answer to some

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Speaker 1: of them super fundamental, which makes me think, how is

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Speaker 1: it that I'm walking around not knowing the answer to

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Speaker 1: all of these fundamental things, but yet I still managed

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Speaker 1: to survive. But no good example is coming to mind

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Speaker 1: right now. But we've got one of those apps on

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Speaker 1: our phone where you can sort of point it at

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Speaker 1: whatever in the night sky and it tells you what

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Speaker 1: it is. And we spend a lot of time sitting

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Speaker 1: on our car at night looking up at stuff, and

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Speaker 1: it's a lot of fun. She asked lots of questions,

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Speaker 1: but nothing's coming to mind right now that I did

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Speaker 1: not know the answer to. What's your favorite question your

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Speaker 1: kids have asked you? One of my favorite questions my

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Speaker 1: kids have asked me are questions like where are we

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Speaker 1: in the universe. You know, they're just getting used to

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Speaker 1: the idea of like our houses in the neighborhood, and

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Speaker 1: the neighborhood is in the city, and that city is

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Speaker 1: in a state somewhere we have like a location and address,

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Speaker 1: and so they wanted to know, like, where are we

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Speaker 1: in the universe? What's our like universe address? And of course,

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Speaker 1: you know, the hardcore physics answer is that every place

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Speaker 1: in the universe is the same, and physics doesn't care

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Speaker 1: about location and translationally and variant and stuff. But that

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Speaker 1: answer is not very satisfying for a four year old. Yeah,

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Speaker 1: that's why it's a bummer to have a physicist for

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Speaker 1: a dad. But instead I try to describe to them,

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Speaker 1: you know, what the galaxy looks like, and how the

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Speaker 1: galaxy fits in with other galaxies, and what we know

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Speaker 1: about sort of our cosmic neighborhood. And the thing I

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Speaker 1: love about their questions is that they are both easy

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Speaker 1: and hard. They're like easy to ask but sometimes hard

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Speaker 1: to answer. And they're the obvious questions, as you said,

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Speaker 1: that you don't always think about when you're walking around

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Speaker 1: the world. But that's why I think that children really

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Speaker 1: are sometimes the most natural scientists, because they don't just

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Speaker 1: accept things as they are. They ask questions about the

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Speaker 1: and say why is it this way or is it

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Speaker 1: that way? After all? Totally, And what I love about

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Speaker 1: Ada is that she'll tell me that I'm wrong. I

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Speaker 1: wish I had that confidence. So you know, not only

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Speaker 1: do they ask good questions, but they still have the

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Speaker 1: confidence of children to be like, no, I don't think so.

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Speaker 1: And so today in the podcast, we'll be talking about

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Speaker 1: a question which seems to have an obvious answer. So

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Speaker 1: on today's program will be answering the question how many

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Speaker 1: moons does the Earth have? So, Kelly, tell me what

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Speaker 1: you thought when you saw that we would be talking

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Speaker 1: about this today. So you sent me a list of

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Speaker 1: topics we could talk about, And when I read this one,

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Speaker 1: I thought, well, the answer seems obvious. The answer is one.

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Speaker 1: And if the answer seems obvious, then either Daniel needs

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Speaker 1: to be fired because he's not asking good questions anymore,

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Speaker 1: or there's something fundamental that I'm missing, and it's probably

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Speaker 1: the second. And so I suggested that we talked about

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Speaker 1: this one because I figured this was a question that

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Speaker 1: would teach me something new. Awesome. This is a fun

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Speaker 1: question to dig into. We get to hear about like

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Speaker 1: what exactly is a moon, what counts as a moon,

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Speaker 1: even a little bit about the etymology of the word

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Speaker 1: moon and when it came into use, and what else

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Speaker 1: is out there orbiting around the Earth and could you

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Speaker 1: call it a moon? So, as usual, before I dug

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Speaker 1: into this, I wanted to know what everybody else out

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Speaker 1: there thought. Sometimes I used to walk around the campus

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Speaker 1: if you see Irvine and ask students there these questions

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Speaker 1: to see what the general level of knowledge was or confusion.

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Speaker 1: These days, of course, because the pandemic, I'm sending emails

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Speaker 1: out into the Internet asking listeners to speculate baselessly without

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Speaker 1: the chance to do any research on these difficult physics questions.

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Speaker 1: Did you actually stop students on the campus and ask

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Speaker 1: them how many moons does they are? Have? No, I

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Speaker 1: haven't because this question is too recent, But I wonder

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Speaker 1: what they would say. I've noticed that our listeners tend

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Speaker 1: to give better informed answers than the random you see

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Speaker 1: Irvine student. Nothing against you see Irvine. Of course, our

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Speaker 1: listeners may just be like a subset of the universe

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Speaker 1: that's more interested in understanding the universe. But I hope

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Speaker 1: one day to get back to campus and getting to

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Speaker 1: ask the students those questions. It was fun to sort

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Speaker 1: of see their faces when I asked them these questions.

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Speaker 1: I bet you have a reputation as being one of

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Speaker 1: the like super weird professors. Well, you know, I don't

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Speaker 1: dress very fancy, so maybe they just think I'm some

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Speaker 1: random homeless person asking them hard physical questions. Every college

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Speaker 1: has homeless person or physics professor, it can be hard

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Speaker 1: to tell the difference, physics professor, you can't tell the

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Speaker 1: difference between Yeah, anyway, Thank you to everybody who volunteered

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Speaker 1: to answer these questions. If you'd like to participate for

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Speaker 1: a future episode of the podcast, please write to me

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Speaker 1: two questions at Daniel and Jorge dot com. Here's what

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Speaker 1: some of our listeners had to say. The obvious answer

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Speaker 1: that pops into my head immediately would be one. So

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Speaker 1: I'm pretty sure that answer is wrong. Well, we have

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Speaker 1: just our celebrity moon, the moon, and I don't know,

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Speaker 1: maybe we might have caught up some small objects there,

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Speaker 1: probably a Deslo car elon musk scent, who knows. I

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Speaker 1: don't know exactly. I'm one sure that the Earth has

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Speaker 1: two moons, the classic moon that we see in the

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Speaker 1: sky and Keith Moon. I would say the Earth has

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Speaker 1: one moon. I don't know if you would consider satellites

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Speaker 1: or a space station a moon because the orbit the Earth,

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Speaker 1: but I would probably just consider one moon. Well, I

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Speaker 1: guess this depends on your definition of moon the natural moons.

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Speaker 1: It has the one large natural moon, and I believe

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Speaker 1: they've discovered a couple of asteroids that have been captured

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Speaker 1: in loose enough for bits that they're probably temporary. If

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Speaker 1: you're going to call any artificial uh satellite a moon,

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Speaker 1: which they've been called artificial moons, then that number goes

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Speaker 1: into the millions, depending on how small a particle you

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Speaker 1: want to count. There's nuts and bolts and pieces of

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Speaker 1: rocket and larger things that satellites, fragments of satellites that

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Speaker 1: have collided with each other, so uh, a whole lot

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Speaker 1: of them, all right, Kelly, So what do you think

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Speaker 1: about our listeners responses here? I thought there were some

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Speaker 1: very insightful responses, you know. One of them was essentially

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Speaker 1: asking questions about maybe how do we define moons. I

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Speaker 1: thought somebody had a clever thought that the Tesla car

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Speaker 1: might now be sort of orbiting, although I think of

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Speaker 1: the Tesla car was shot Mars word instead of moonword.

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Speaker 1: But it was clear that people sort of thought through

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Speaker 1: their answers, and yeah, they had some clever answers. What

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Speaker 1: do you think? Yeah, I was impressed as well. In

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Speaker 1: the end, of course, it's going to come down to

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Speaker 1: the definition. I hope that we end up with the

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Speaker 1: definition of moon that doesn't allow Elon Musk to have

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Speaker 1: created his own personal moon. That would seems sort of unsatisfying.

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Speaker 1: That would be too much power for one person. The

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Speaker 1: dude's already a billionaire and owns three like really valuable

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Speaker 1: companies like it, doesn't need to create astronomical objects on

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Speaker 1: top of all of it. Although he wants to create

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Speaker 1: a Mars colony, which is maybe even more powerful than

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Speaker 1: creating a moon. So I guess we'll have to see

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Speaker 1: what the future holds. Do you think that's because he

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Speaker 1: wants to be dictator of Mars? I like joking about

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Speaker 1: that with Zack. Yes, he claims he wants a representative

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Speaker 1: not a direct democracy, So we'll see what happens when

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Speaker 1: the time comes. Well, if he gets to pick who

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Speaker 1: goes to Mars, and they're probably going to elect him

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Speaker 1: president anyway. But let's get back to the topic. We're

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Speaker 1: not talking about Elon Musk's plan to colonize Mars. We're

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Speaker 1: talking about moons and how many moons the Earth has

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Speaker 1: and what exactly is a moon? So let's dig into

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Speaker 1: that first and talk about what qualifies as a moon. So,

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Speaker 1: without doing any research, Kelly, what would you use to

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Speaker 1: define a moon? So I would have guessed that a

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Speaker 1: moon is a big thing that isn't bigger than the

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Speaker 1: planet that it orbits. So a big thing that orbits

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Speaker 1: around a planet, and it has to be big, but

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Speaker 1: it can't be bigger than the thing that it's orbiting around.

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Speaker 1: That's how I would have defined it. But but probably

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Speaker 1: that's wrong. And then your definition would it have to

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Speaker 1: be natural or could be manned? Me that? Could we

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Speaker 1: build an artificial moon? Oh h no, No, I've always

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Speaker 1: thought of it as being natural. Yeah, what about you? Well,

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Speaker 1: I really wasn't sure because it seems like in lots

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Speaker 1: of directions there are arbitrary distinctions you have to make.

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Speaker 1: And that's the problem often in astronomy is that the

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Speaker 1: categories between things get blurred, and you always find something

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Speaker 1: right on the edge between the different categories, and in

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Speaker 1: the end, you know, we're just we're looking at the

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Speaker 1: universe and we're trying to categorize it to understand is

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Speaker 1: that we can talk about it together. Doesn't mean that

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Speaker 1: those categories actually reflect something deep and true about the universe.

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Speaker 1: There's sometimes just the words we've used to describe stuff,

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Speaker 1: and so as we see more stuff out there in

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Speaker 1: the universe, we're gonna find things that break those categories.

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Speaker 1: But the definition that I found for moon is that

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Speaker 1: it has to be a quote natural body, right, So

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Speaker 1: it needs to be a natural body that's orbiting a planet.

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Speaker 1: And to me already this is problem that like a

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Speaker 1: natural body means not like a human made satellite. So

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Speaker 1: we built a death Star for example, Officially that wouldn't

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Speaker 1: qualify as a moon. But what if we just like

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Speaker 1: you know, pulled out a huge chunk of Earth and

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Speaker 1: threw it out into space and then it went into

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Speaker 1: orbit around the Earth. Is that a natural body? It's

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Speaker 1: like made of rock, right, It's essentially the same process

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Speaker 1: that created our moon as we understand it. But I

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Speaker 1: think according to this definition, it wouldn't be a moon

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Speaker 1: because you know, it would have been like as the

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Speaker 1: result of a human process. It really does seem like

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Speaker 1: if you just took a chunk of earth and you

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Speaker 1: put it up there, it should count. But I suppose

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Speaker 1: satellites are just chunks of Earth that we've we've done

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Speaker 1: things too, that we send up into space, and so

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Speaker 1: maybe it shouldn't count. Yeah, exactly, That's where I was going.

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Speaker 1: What is a satellite other than like an ultra refined

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Speaker 1: piece of Earth that you've somehow, you know, manipulated into

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Speaker 1: a complex technological object. But in the end, it's a

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Speaker 1: piece of the Earth that we've launched into space. And

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Speaker 1: you know, for those of you who don't know the

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Speaker 1: history of our moon, we think that our moon is

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Speaker 1: basically a big chunk of Earth that was vaulted out

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Speaker 1: into space when another proto planet hit Earth when it

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Speaker 1: was very very young, and this collision led to this

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Speaker 1: enormous blab of stuff getting tossed out there, which eventually

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Speaker 1: coalesced into the Moon. And when we studied the surface

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Speaker 1: of the Moon, we found elements of it which look

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Speaker 1: exactly the same as elements of the surface of the Earth,

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Speaker 1: which suggests that they really do have sort of a

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Speaker 1: common origin. So this definition of a moon being a

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Speaker 1: natural body not a human made object is a little tricky,

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Speaker 1: and I don't think the definition there is very clear.

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Speaker 1: Can I ask a sort of tangential question, of course, So, well,

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Speaker 1: Zach and I were reading about the Moon. We came

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Speaker 1: across this fact that the Moon is sort of carbon poor,

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Speaker 1: like maybe there's some carbon up there, but you're gonna

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Speaker 1: have trouble growing plants and stuff because there's not a

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Speaker 1: lot of carbon. If the Moon is just a chunk

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Speaker 1: of Earth that got expelled, why do we have so

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Speaker 1: much carbon and they have so little. Is that the

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Speaker 1: result of natal processes that happened after the Moon got

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Speaker 1: cut off partly, Yeah, Mostly the Earth and the Moon

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Speaker 1: are made up of very similar stuff. It's mostly oxygen

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Speaker 1: and silicon and calcium and iron and that kind of stuff.

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Speaker 1: That's because we think that the Moon and the Earth

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Speaker 1: are made up of the remnants of a huge collision

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Speaker 1: between the proto Earth and a Mars sized planet, like

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Speaker 1: fifty million years after the Solar system formed, and the

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Speaker 1: remnants of that huge collision coalesced into the Earth and

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Speaker 1: into the Moon. But you're right that there is very

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Speaker 1: little carbon on the Moon, but there is carbon on

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Speaker 1: the Earth's surface, and we're not sure why. One theory

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Speaker 1: is that carbon tends to form very volatile compounds, things

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Speaker 1: that would end up in an atmosphere if the Moon

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Speaker 1: could keep one. So the Earth hangs onto some of

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Speaker 1: these things, some of this carbon, because it's big enough

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Speaker 1: to keep hold of its atmosphere it has more gravity,

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Speaker 1: But the Moon can't. Anything like an atmosphere on the

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Speaker 1: Moon just boils away. Interesting okay, thanks. So the definition

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Speaker 1: of a moon is that needs to be a natural

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Speaker 1: a body in orbit around a planet, and you said

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Speaker 1: that it needs to be big. Officially, technically there's no

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Speaker 1: minimum size to a moon. A moon could be like huge,

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Speaker 1: like our moon, or you know, according to astronomers, it's

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Speaker 1: okay to have a moon that's like a kilometer in size.

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Speaker 1: I find that very unsatisfying. Like to me, a moon

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Speaker 1: is something that you should be able to, like put

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Speaker 1: a settlement on one day, and you can't really do

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Speaker 1: that with a one kilometer sized quote unquote moon. I

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Speaker 1: don't know. I don't want to buy that, but apparently

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Speaker 1: it's part of the definition. It would be like the

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Speaker 1: little prints right walking around this tiny little planet. But

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Speaker 1: I think that comes from our experience, right, just because

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Speaker 1: we have this one big moon, we tend to think

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Speaker 1: that's what you gotta have in a moon. But as

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Speaker 1: well talk about later, so many planets in the Solar

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Speaker 1: System don't have a huge moon, to have a lot

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Speaker 1: of smaller moons, And so part of the joy of

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Speaker 1: astronomy and and of exploring the universe is discovering that

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Speaker 1: our corner of the universe is weird, is unusual, is

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Speaker 1: not representative, and we've got to sort of like stretch

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Speaker 1: our mind then get used to a different way of

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Speaker 1: thinking about what a moon is. Yeah, it is really

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Speaker 1: hard to wrap your mind around just how different it is.

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Speaker 1: And yeah, I'm very earth centric. I guess I would

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Speaker 1: like moons to all sort of fits in a nice

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Speaker 1: little mold that matches the moon that I have, and

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Speaker 1: you touch it on really all the important issues. I

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Speaker 1: think that was really tremendous. The other thing you mentioned

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Speaker 1: is that it shouldn't be bigger than the planet, right,

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Speaker 1: And in the definition of a moon, officially, the upper

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Speaker 1: limit on the size of a moon is pretty vague,

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Speaker 1: Like what happens when the moon approaches the size of

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Speaker 1: the planet. Then you might ask, like, well, which one

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Speaker 1: is the planet and which one is the moon? Right?

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Speaker 1: Or if they're exactly equal size, could you consider them

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Speaker 1: to be like a binary planet system? So where does

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Speaker 1: our moon fall relative? And they'll like Earth to Moon

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Speaker 1: ratio side, Like, is our moon big for a moon?

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Speaker 1: Is it the biggest relative to the size of the

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Speaker 1: planet it orbits is? So is our moon weird relative

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Speaker 1: to the other moons? Our moon is very weird. Our

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00:16:55,320 --> 00:16:58,920
Speaker 1: moon is basically that megachild. The diameter of the Moon

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Speaker 1: is more than a quarter of the diameter of the Earth,

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Speaker 1: and that's the biggest moon to planet ratio in the

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Speaker 1: Solar System by like a factor of five. There's no

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Speaker 1: other planet out there that has such a big moon

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Speaker 1: relative to the planet. Like there are moons of Jupiter

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Speaker 1: that are roughly the same size as our moon, but

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Speaker 1: of course Jupiter is huge, and so relative to the

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Speaker 1: size of Jupiter, those moons are very very small, So

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Speaker 1: we have a really weird big moon. You know, it's

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Speaker 1: kind of amazing that we've managed to figure out anything,

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Speaker 1: which is sort of a phrase that, if I'm remembering correctly,

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Speaker 1: I've said in almost every single one of these episodes

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Speaker 1: we've done together. But it seems like, you know, our

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Speaker 1: Solar System is so weird, and our planet and the

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Speaker 1: moon is so weird. It gives us such a weird

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Speaker 1: frame of reference. But I know, it's exciting that we

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Speaker 1: can still figure stuff out. Yeah, and it's a real

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Speaker 1: journey to peel away these preconceptions and understand that things

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Speaker 1: we thought were fundamental, things we thought we're obvious or universal,

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Speaker 1: are really just unusual. You know. It's just like when

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Speaker 1: you go traveling and you discover like, oh, not everybody

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Speaker 1: drinks coffee for breakfast. You know, it turns out there

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00:17:59,320 --> 00:18:01,600
Speaker 1: are other ways to live, and that's the joy of

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Speaker 1: exploring the universe, you know, discovering the tea is also

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00:18:04,480 --> 00:18:08,159
Speaker 1: acceptable at breakfast times. No, no, no, no, no, no,

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Speaker 1: that's just wrong. One fact that I really liked while

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Speaker 1: I was reading through here was that those like one

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Speaker 1: kilometer size moons are sometimes called moonlits. And I thought

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Speaker 1: that was super cute. So I asked my seven year

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Speaker 1: old today. I was like, how many moons does the

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Speaker 1: Earth have? So she, being a very clever kid, was like, well,

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Speaker 1: I thought it was one, but you're asking me this,

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Speaker 1: so what does that mean? And and so I told

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Speaker 1: her like, well, you know you can have these little

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Speaker 1: things called moonlits. And she said, well, what does that mean?

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Speaker 1: And so I tried to explain that let's means little

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Speaker 1: things and she was like, well, when else does it

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Speaker 1: mean that? And I had a like, uh, you know,

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Speaker 1: like a moment of not being able to figure it out,

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Speaker 1: but I came up with piglets and outlets, and I

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00:18:46,480 --> 00:18:48,480
Speaker 1: was very proud of myself. So anyway, that was a

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Speaker 1: fun moment with the seven year old today. Yeah, I

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Speaker 1: love those little endings lits and like, it's just like

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00:18:53,480 --> 00:18:57,280
Speaker 1: the diminutive in Spanish, you know, eto or eno or

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00:18:57,320 --> 00:18:59,640
Speaker 1: these kind of things in romance languages. So I'm glad

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00:18:59,640 --> 00:19:01,440
Speaker 1: that we have those in English. Also, you could really

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00:19:01,480 --> 00:19:04,000
Speaker 1: stick them on anything, you know, like I'm not having dessert,

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00:19:04,000 --> 00:19:08,840
Speaker 1: I'm having dessert lits. It makes everything cuter, it really does.

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00:19:09,280 --> 00:19:11,159
Speaker 1: So where are we with the moons? Moons have to

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Speaker 1: be a natural body orbiting a planet. No minimum size.

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Speaker 1: The oppera limit is kind of vague. One thing I

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00:19:17,760 --> 00:19:20,760
Speaker 1: read suggested that you could effectively describe an upper limit

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00:19:20,840 --> 00:19:24,400
Speaker 1: on the moon by requiring that the center of mass

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00:19:24,440 --> 00:19:28,239
Speaker 1: of the planet and moon together should be inside the

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00:19:28,280 --> 00:19:30,960
Speaker 1: diameter of the planet. Right, So the center of mass

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00:19:30,960 --> 00:19:33,719
Speaker 1: of two objects is sort of like the weighted average

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00:19:34,040 --> 00:19:36,320
Speaker 1: of all of their stuff. If you've got more stuff

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00:19:36,320 --> 00:19:38,159
Speaker 1: in the planet than in the moon, it's going to

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00:19:38,200 --> 00:19:41,040
Speaker 1: be closer to the planet mathematically and physically. It's actually

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00:19:41,160 --> 00:19:43,840
Speaker 1: the location that the two things are orbiting. Right. We

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00:19:43,960 --> 00:19:46,600
Speaker 1: say that the Moon, for example, orbits the Earth, but

397
00:19:46,680 --> 00:19:49,840
Speaker 1: actually the two things are orbiting each other, or more precisely,

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00:19:50,040 --> 00:19:53,480
Speaker 1: they're both orbiting the center of mass of the two things.

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00:19:53,720 --> 00:19:55,680
Speaker 1: And if you have two things that are equal mass,

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00:19:55,800 --> 00:19:58,280
Speaker 1: then their center of masses right between them. If one

401
00:19:58,280 --> 00:20:00,720
Speaker 1: of them is infinitely massive, then the center of mass

402
00:20:00,800 --> 00:20:03,159
Speaker 1: is at the center of that very massive object. In

403
00:20:03,160 --> 00:20:05,920
Speaker 1: a more realistic scenario, where one thing is very massive

404
00:20:05,960 --> 00:20:07,919
Speaker 1: and one thing is much smaller, you can have the

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00:20:07,920 --> 00:20:10,640
Speaker 1: center of mass of the system of the two things

406
00:20:11,040 --> 00:20:14,399
Speaker 1: be close to the center of the larger object. And

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00:20:14,440 --> 00:20:16,919
Speaker 1: so here the definition is like, is the center of

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00:20:17,000 --> 00:20:20,680
Speaker 1: mass of the two objects underneath the ground within the

409
00:20:20,920 --> 00:20:24,160
Speaker 1: radius of the larger object. That's sort of a cool definition.

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00:20:24,320 --> 00:20:25,359
Speaker 1: That is a cool So I have a couple of

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00:20:25,440 --> 00:20:29,000
Speaker 1: questions to see if I understand. So one, does it

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00:20:29,040 --> 00:20:32,399
Speaker 1: depend on how far apart the things are or is

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00:20:32,400 --> 00:20:34,879
Speaker 1: it like you just when you make this comparison, you

414
00:20:34,880 --> 00:20:36,720
Speaker 1: you know, sort of mentally put these things right next

415
00:20:36,760 --> 00:20:38,800
Speaker 1: to each other and then compare the center of mass.

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00:20:38,920 --> 00:20:41,600
Speaker 1: It definitely depends on how far apart they are, right

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00:20:41,680 --> 00:20:44,520
Speaker 1: because for example, if they're equally massive, you'd be right

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00:20:44,560 --> 00:20:47,200
Speaker 1: between them, and that definitely depends on the distance between

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00:20:47,240 --> 00:20:49,159
Speaker 1: the two objects. Yes, and so that would mean you

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00:20:49,200 --> 00:20:51,720
Speaker 1: have two planets as opposed to a moon and a

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00:20:51,760 --> 00:20:55,160
Speaker 1: planet in that definition. And so so you have two

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00:20:55,160 --> 00:20:58,239
Speaker 1: things that are like one is just a little bit

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00:20:58,280 --> 00:21:00,760
Speaker 1: smaller than the other, and one is big er, but

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00:21:00,840 --> 00:21:05,400
Speaker 1: the smaller one is made out of something much more

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00:21:06,000 --> 00:21:08,480
Speaker 1: massive or dense or I'm not quite sure what word

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00:21:08,480 --> 00:21:11,480
Speaker 1: I'm looking for here. Could the smaller thing end up

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00:21:11,520 --> 00:21:14,360
Speaker 1: being the planet that gets orbited by a bigger thing

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00:21:14,400 --> 00:21:18,480
Speaker 1: because it has more like gravitational pull? Absolutely? Yeah. For example,

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00:21:18,800 --> 00:21:21,720
Speaker 1: if you had something orbiting a black hole, right, a

430
00:21:21,760 --> 00:21:24,760
Speaker 1: super duper dense object, then the center of mass of

431
00:21:24,760 --> 00:21:27,320
Speaker 1: the system is definitely going to be within the event horizon,

432
00:21:27,440 --> 00:21:29,600
Speaker 1: even if though the black hole could be smaller. Right,

433
00:21:29,600 --> 00:21:31,680
Speaker 1: black holes are very very compact. They don't have to

434
00:21:31,720 --> 00:21:34,760
Speaker 1: be very very large, but they are supermassive. So that's awesome.

435
00:21:34,800 --> 00:21:37,639
Speaker 1: You're really like pushing the boundaries of this definition. But

436
00:21:37,720 --> 00:21:39,399
Speaker 1: I don't know. I guess a black hole could have

437
00:21:39,440 --> 00:21:41,440
Speaker 1: a planet orbiting it. I'm not sure if you would

438
00:21:41,440 --> 00:21:43,360
Speaker 1: call that a planet or a moon, right, if you're

439
00:21:43,440 --> 00:21:46,080
Speaker 1: orbiting a black hole, Yeah, it's trippy, I guess, I,

440
00:21:46,720 --> 00:21:51,080
Speaker 1: as a not physicist, find it sort of unsatisfying that

441
00:21:51,119 --> 00:21:54,080
Speaker 1: if the moon is too far away, it might or

442
00:21:54,119 --> 00:21:56,400
Speaker 1: if something that feels sort of moon like is too

443
00:21:56,400 --> 00:21:59,080
Speaker 1: far away, it wouldn't count as a moon because the

444
00:21:59,119 --> 00:22:02,399
Speaker 1: center of masses is not within the bigger body or something.

445
00:22:02,640 --> 00:22:05,560
Speaker 1: It feels like distance shouldn't matter for the definition, But

446
00:22:05,960 --> 00:22:08,040
Speaker 1: that's a biologist take on it. Well, it definitely has

447
00:22:08,040 --> 00:22:10,560
Speaker 1: to be in orbit. And I think that one problem

448
00:22:10,720 --> 00:22:13,000
Speaker 1: with this whole categorization is that this is like a

449
00:22:13,119 --> 00:22:16,080
Speaker 1: natural hierarchy. I mean, you have the Sun and the

450
00:22:16,119 --> 00:22:19,480
Speaker 1: stuff orbiting around the Sun, and then you call those planets,

451
00:22:19,480 --> 00:22:21,960
Speaker 1: but that's sort of arbitrary because they're orbiting around the Sun.

452
00:22:22,320 --> 00:22:25,119
Speaker 1: And then there's things orbiting around the planets, right, and

453
00:22:25,160 --> 00:22:27,360
Speaker 1: you call those moons. In the end, it's just sort

454
00:22:27,359 --> 00:22:30,440
Speaker 1: of a natural hierarchy of stuff orbiting stuff that's orbiting

455
00:22:30,480 --> 00:22:33,440
Speaker 1: other stuff, and our categorization of it is you're really

456
00:22:33,440 --> 00:22:35,760
Speaker 1: going to try to draw lines there where they really

457
00:22:35,800 --> 00:22:39,560
Speaker 1: aren't lines. Yeah, but that's like a fundamental problem with science.

458
00:22:39,600 --> 00:22:43,119
Speaker 1: You know, in biology, we categorize things, and constantly nature

459
00:22:43,200 --> 00:22:45,480
Speaker 1: does not care how we categorize it. She moves away

460
00:22:45,480 --> 00:22:47,639
Speaker 1: outside of our categories. Yeah, I guess it's tough just

461
00:22:47,680 --> 00:22:50,560
Speaker 1: finding a definition that is useful I guess in biology

462
00:22:50,760 --> 00:22:52,800
Speaker 1: there was a huge revolution a couple hundred years ago,

463
00:22:52,880 --> 00:22:55,280
Speaker 1: right because you guys had been categorizing stuff based on

464
00:22:55,480 --> 00:22:58,600
Speaker 1: how it looked and what it did, and then discovered

465
00:22:58,760 --> 00:23:01,840
Speaker 1: the genetic relation ships between everything, and that there was

466
00:23:01,920 --> 00:23:05,159
Speaker 1: actually a real, true organization to all these animals that

467
00:23:05,280 --> 00:23:08,439
Speaker 1: didn't necessarily respect how they looked or how we observe

468
00:23:08,560 --> 00:23:10,479
Speaker 1: them well. And then it turns out that, you know,

469
00:23:10,560 --> 00:23:13,359
Speaker 1: how do you define species? That's actually a pretty difficult question.

470
00:23:13,440 --> 00:23:15,720
Speaker 1: The tree of life doesn't just branch, it sort of comes,

471
00:23:15,800 --> 00:23:19,399
Speaker 1: the branches come back together and you get horizontal gene transfer.

472
00:23:19,440 --> 00:23:22,480
Speaker 1: And how do you categorize species of bacteria when they're

473
00:23:22,480 --> 00:23:25,600
Speaker 1: swapping jeans all the time, and it gets complicated fast. Well,

474
00:23:25,600 --> 00:23:28,280
Speaker 1: in physics, it's interesting they think about how these words

475
00:23:28,320 --> 00:23:30,920
Speaker 1: were used for a long time. People use the word

476
00:23:31,040 --> 00:23:34,520
Speaker 1: satellite to also refer to moons, and this is before

477
00:23:34,560 --> 00:23:38,520
Speaker 1: we had things in space like GPS and telecommunications, satellites

478
00:23:38,560 --> 00:23:41,440
Speaker 1: and you know, laser weapons and all that kind of stuff. Now,

479
00:23:41,440 --> 00:23:43,879
Speaker 1: when you say satellite, you think of something people build,

480
00:23:43,920 --> 00:23:47,200
Speaker 1: maybe electronics and launched into space. But before spot Nick,

481
00:23:47,240 --> 00:23:51,680
Speaker 1: before ninety seven, astronomers used the word satellite to talk

482
00:23:51,680 --> 00:23:55,720
Speaker 1: about anything orbiting another object, and so they didn't really

483
00:23:55,800 --> 00:24:00,320
Speaker 1: use the word moon scientifically. They referred to Luna, for example,

484
00:24:00,480 --> 00:24:04,119
Speaker 1: as Earth satellite. Then when they launched sput Nick, they realized,

485
00:24:04,119 --> 00:24:05,760
Speaker 1: whole on a second, what are we going to call that?

486
00:24:06,000 --> 00:24:08,679
Speaker 1: And so they started to use the word artificial satellite.

487
00:24:08,680 --> 00:24:10,679
Speaker 1: But that was a little bit too cumbersome, and so

488
00:24:10,800 --> 00:24:14,040
Speaker 1: now we just say satellite when we mean artificial satellite.

489
00:24:14,280 --> 00:24:17,439
Speaker 1: And then moon, which was a word mostly used like

490
00:24:17,520 --> 00:24:20,680
Speaker 1: in science fiction and a sort of popular culture, became

491
00:24:20,800 --> 00:24:23,639
Speaker 1: a more official scientific word. I think that's sort of

492
00:24:23,640 --> 00:24:26,879
Speaker 1: cool that the scientists adopted a word from sort of

493
00:24:26,920 --> 00:24:29,800
Speaker 1: common usage. That's totally fascinating. And I've been reading about

494
00:24:29,880 --> 00:24:32,040
Speaker 1: the space race and I didn't know this history of

495
00:24:32,040 --> 00:24:34,880
Speaker 1: the word satellite. And when I saw that they named

496
00:24:34,880 --> 00:24:37,239
Speaker 1: spot Nick an artificial satellite, I was like, well, that's

497
00:24:37,280 --> 00:24:39,760
Speaker 1: sort of clunk. Why not just call it satellite? But

498
00:24:39,840 --> 00:24:42,639
Speaker 1: it makes sense now. A lot of the fathers of

499
00:24:42,720 --> 00:24:46,480
Speaker 1: rocket science or whatever. We're really into sci fi. I

500
00:24:46,480 --> 00:24:49,200
Speaker 1: think almost all of the fathers of rocket science claimed

501
00:24:49,200 --> 00:24:51,879
Speaker 1: that they were inspired by Jules Verns. What is it

502
00:24:51,920 --> 00:24:54,000
Speaker 1: called to the moon? I wonder if the fact that

503
00:24:54,040 --> 00:24:56,560
Speaker 1: they were all super into sci fi sort of helped

504
00:24:56,880 --> 00:24:59,480
Speaker 1: get the word moon into the scientific literature. Yeah it

505
00:24:59,480 --> 00:25:01,600
Speaker 1: makes me one or what else? Like will in the

506
00:25:01,720 --> 00:25:04,159
Speaker 1: future be part of science. You know, things that we

507
00:25:04,200 --> 00:25:06,080
Speaker 1: say but you wouldn't hear a scientists say, you know,

508
00:25:06,119 --> 00:25:09,119
Speaker 1: like a shooting star is our word for a meteor,

509
00:25:09,240 --> 00:25:11,000
Speaker 1: but you never see that in the science paper. But

510
00:25:11,040 --> 00:25:13,720
Speaker 1: maybe someday in the future, you know, the language will

511
00:25:13,920 --> 00:25:18,719
Speaker 1: transmogrify itself into official scientific physics speaker could be. All right,

512
00:25:18,840 --> 00:25:21,040
Speaker 1: So we have our definition of a moon. It has

513
00:25:21,080 --> 00:25:25,040
Speaker 1: to be a natural body, right, not something engineered by

514
00:25:25,160 --> 00:25:28,919
Speaker 1: humanity or elon Musk. Has to orbit a planet. But

515
00:25:29,080 --> 00:25:32,639
Speaker 1: there's really no minimum size to it, though there seems

516
00:25:32,640 --> 00:25:34,680
Speaker 1: to be some sort of sense of an upper limit

517
00:25:34,720 --> 00:25:37,560
Speaker 1: that you shouldn't have your moon being larger than your planet.

518
00:25:37,640 --> 00:25:40,199
Speaker 1: All right, So, now that we have our definition, or

519
00:25:40,200 --> 00:25:41,960
Speaker 1: at least a definition we're gonna work with for the

520
00:25:42,000 --> 00:25:44,359
Speaker 1: rest of this episode, let's take a break before we

521
00:25:44,400 --> 00:25:59,600
Speaker 1: move back to figuring out exactly how many moons Earth has.

522
00:25:59,600 --> 00:26:03,439
Speaker 1: So we have a definition. Now, how many moons do

523
00:26:03,520 --> 00:26:06,760
Speaker 1: we have, Daniel, So let's count them first. Of course,

524
00:26:06,920 --> 00:26:09,439
Speaker 1: we have the number one candidate. The classic moon, the

525
00:26:09,480 --> 00:26:13,000
Speaker 1: one you're familiar with, the one we all grew up loving. Right,

526
00:26:13,320 --> 00:26:16,000
Speaker 1: this is the moon we call the moon, which is

527
00:26:16,119 --> 00:26:18,240
Speaker 1: sort of a silly name, right, calling the moon the moon.

528
00:26:18,280 --> 00:26:20,760
Speaker 1: It reminds me actually, when I was a kid, we

529
00:26:20,800 --> 00:26:22,960
Speaker 1: had a cat and nobody could agree on what to

530
00:26:23,000 --> 00:26:25,600
Speaker 1: call the cat, so we just called it the cat,

531
00:26:26,240 --> 00:26:29,240
Speaker 1: and that just became its name. And for a while

532
00:26:29,240 --> 00:26:31,600
Speaker 1: I felt sad for like, oh, poor cat doesn't get

533
00:26:31,600 --> 00:26:34,639
Speaker 1: a name, But he didn't care. It got fed, it

534
00:26:34,720 --> 00:26:37,240
Speaker 1: got pet it doesn't need a name. I think it's

535
00:26:37,280 --> 00:26:40,320
Speaker 1: good that you became more creative that you got I

536
00:26:40,320 --> 00:26:43,520
Speaker 1: can't tell if calling it the moon is very egocentric,

537
00:26:43,600 --> 00:26:45,960
Speaker 1: like that is our moon, so it is the moon,

538
00:26:46,280 --> 00:26:49,240
Speaker 1: or if it just represents a lack of creativity. Hard

539
00:26:49,280 --> 00:26:52,000
Speaker 1: to say. Well, as we were saying earlier, it's really weird,

540
00:26:52,160 --> 00:26:54,480
Speaker 1: Like it's huge. It's more than a quarter of the

541
00:26:54,520 --> 00:26:57,320
Speaker 1: diameter of the Earth in the Solar System. The next

542
00:26:57,440 --> 00:26:59,919
Speaker 1: largest moon relative to his planet is one of the

543
00:27:00,000 --> 00:27:02,199
Speaker 1: moons of Neptune, which is almost six percent of the

544
00:27:02,240 --> 00:27:05,480
Speaker 1: diameter of Neptune. So that's a pretty big gap. Like

545
00:27:05,880 --> 00:27:09,160
Speaker 1: mostly moons are small compared to their planet. The moon

546
00:27:09,320 --> 00:27:11,399
Speaker 1: is really a very weird and Or and I did

547
00:27:11,400 --> 00:27:13,880
Speaker 1: a whole episode about how the Earth got its moon

548
00:27:13,920 --> 00:27:16,800
Speaker 1: and the various theories and how people are testing those,

549
00:27:16,800 --> 00:27:18,600
Speaker 1: and so if you're interested in the details of the

550
00:27:18,720 --> 00:27:22,359
Speaker 1: history of the moon, then good check out that episode.

551
00:27:22,440 --> 00:27:24,560
Speaker 1: But it's interesting that, you know, in the sort of

552
00:27:24,560 --> 00:27:27,760
Speaker 1: the history of astronomy I was reading about this, people

553
00:27:27,800 --> 00:27:32,080
Speaker 1: didn't really think about the Moon as a moon until

554
00:27:32,200 --> 00:27:35,879
Speaker 1: they discovered Jupiter's moons. Like people were looking up in

555
00:27:35,960 --> 00:27:38,239
Speaker 1: the sky and they saw, of course stars and they

556
00:27:38,280 --> 00:27:40,479
Speaker 1: saw the moon, but they just thought of it as

557
00:27:40,520 --> 00:27:46,000
Speaker 1: like another celestial object. They were wrong. And then you know,

558
00:27:46,040 --> 00:27:49,240
Speaker 1: when Galileo and other folks saw the moons of Jupiter

559
00:27:49,240 --> 00:27:50,960
Speaker 1: and they're like, hey, look at that, there are things

560
00:27:51,119 --> 00:27:53,560
Speaker 1: orbiting Jupiter. That's when it clicked in the place and

561
00:27:53,560 --> 00:27:56,360
Speaker 1: they're like, wait a second, what Jupiter's got over there

562
00:27:56,440 --> 00:27:59,159
Speaker 1: is the same thing that we've got over here. And

563
00:27:59,200 --> 00:28:01,000
Speaker 1: that's when they really eyes that this was a whole

564
00:28:01,000 --> 00:28:04,400
Speaker 1: new kind of thing in space. That's so interesting. That's

565
00:28:04,440 --> 00:28:06,400
Speaker 1: why it's so important to you know, to learn more

566
00:28:06,400 --> 00:28:08,320
Speaker 1: and to step outside your comfort zone because there's so

567
00:28:08,320 --> 00:28:10,560
Speaker 1: many things that become obvious when you see how other

568
00:28:10,680 --> 00:28:13,320
Speaker 1: things are done, and the moon is actually considered a

569
00:28:13,359 --> 00:28:16,200
Speaker 1: planet for a while, though the definition of a planet

570
00:28:16,200 --> 00:28:18,879
Speaker 1: has also changed. Back then, a planet was just like

571
00:28:19,160 --> 00:28:23,439
Speaker 1: another astronomical object. People didn't really understand the relationship between

572
00:28:23,440 --> 00:28:25,520
Speaker 1: the planets and the stars and all this kind of stuff.

573
00:28:25,760 --> 00:28:28,240
Speaker 1: So if you go back to very early astronomy, what

574
00:28:28,440 --> 00:28:31,560
Speaker 1: these words mean is totally different from what they mean today.

575
00:28:31,880 --> 00:28:34,600
Speaker 1: So it's pretty tricky to read, like you know, early

576
00:28:34,680 --> 00:28:38,080
Speaker 1: astronomical texts. That sounds super confusing. So it makes me wonder.

577
00:28:38,200 --> 00:28:40,880
Speaker 1: So if you can be changing what the definition of

578
00:28:40,920 --> 00:28:44,000
Speaker 1: a planet is, can you have things that are not

579
00:28:44,120 --> 00:28:48,880
Speaker 1: planets that have moons? You can definitely have things that

580
00:28:48,960 --> 00:28:52,479
Speaker 1: are not planets that have stuff orbiting them, and we

581
00:28:52,520 --> 00:28:55,120
Speaker 1: will talk about that later in the episode. There are

582
00:28:55,160 --> 00:28:57,760
Speaker 1: things in the Solar System orbiting other things that are

583
00:28:57,760 --> 00:29:00,800
Speaker 1: not planets, for sure. Sorry I got excited. It is

584
00:29:00,880 --> 00:29:03,640
Speaker 1: very cool. And for example, you know, just as a teaser,

585
00:29:03,800 --> 00:29:08,200
Speaker 1: Pluto no longer considered a planet, but it does have

586
00:29:08,360 --> 00:29:11,560
Speaker 1: things orbiting it, right, Pluto has something which you would

587
00:29:11,560 --> 00:29:15,560
Speaker 1: call a moon, Sharon, which is half the diameter of Pluto.

588
00:29:15,720 --> 00:29:18,000
Speaker 1: So that's pretty fuzzy, like which one is a planet,

589
00:29:18,000 --> 00:29:19,920
Speaker 1: which one is the moon. Pluto is only twice as

590
00:29:20,000 --> 00:29:23,840
Speaker 1: big as its moon. So if Sharon or Charon, however

591
00:29:23,880 --> 00:29:25,880
Speaker 1: you say, it ends up being called the moon, that

592
00:29:25,960 --> 00:29:29,400
Speaker 1: makes our moon a little bit less exciting. Yeah, Or

593
00:29:29,440 --> 00:29:32,240
Speaker 1: if Pluto gets repromoted back into it being a planet,

594
00:29:32,520 --> 00:29:35,200
Speaker 1: then Sharon would be the largest moon relative to a

595
00:29:35,240 --> 00:29:38,240
Speaker 1: planet in the Solar System. But because Pluto's no longer

596
00:29:38,400 --> 00:29:43,560
Speaker 1: technically a planet, Sharon loses that distinction. Sharon shure, Sharon, Alright,

597
00:29:43,600 --> 00:29:46,040
Speaker 1: so everybody knows about the moon. That's not what people

598
00:29:46,040 --> 00:29:48,960
Speaker 1: want to hear about. Are there other things orbiting the

599
00:29:48,960 --> 00:29:52,360
Speaker 1: Earth that could also be considered moons and so at?

600
00:29:52,360 --> 00:29:55,120
Speaker 1: In fact, there are, but they're sort of on the

601
00:29:55,200 --> 00:29:58,400
Speaker 1: border line of whether you would really technically call them

602
00:29:58,440 --> 00:30:00,360
Speaker 1: a moon. One of my favorites, they say, the object

603
00:30:00,360 --> 00:30:02,160
Speaker 1: which I won't even try to pronounce. You're gonna have

604
00:30:02,200 --> 00:30:03,720
Speaker 1: to look it up, but it goes by the name

605
00:30:03,800 --> 00:30:07,520
Speaker 1: of the space being, and it's this object like five

606
00:30:07,680 --> 00:30:12,120
Speaker 1: kilometers in diameter that's orbiting the Sun in the vicinity

607
00:30:12,200 --> 00:30:13,960
Speaker 1: of the Earth. But it seems like we've got to

608
00:30:13,960 --> 00:30:16,800
Speaker 1: try to pronounce it, right, So I'm gonna try crew

609
00:30:16,840 --> 00:30:20,280
Speaker 1: with me, Crew with crew with me. That sounds about right.

610
00:30:20,600 --> 00:30:22,280
Speaker 1: If I had no idea how to pronounce it, I

611
00:30:22,280 --> 00:30:24,120
Speaker 1: would guess that was correct. And I have no idea

612
00:30:24,120 --> 00:30:27,120
Speaker 1: how to pronounce it, so I guess that's correct. I

613
00:30:27,160 --> 00:30:29,320
Speaker 1: don't even know what the like, you know, origin of that,

614
00:30:29,360 --> 00:30:31,800
Speaker 1: what language that comes from. It looks Irish to me,

615
00:30:31,880 --> 00:30:34,440
Speaker 1: and I have I have no reason. I don't actually

616
00:30:34,440 --> 00:30:36,600
Speaker 1: know anything about the Irish language. So mean, maybe I

617
00:30:36,640 --> 00:30:39,480
Speaker 1: should stop. Maybe it's Gaelic for space being. Somebody out

618
00:30:39,480 --> 00:30:41,480
Speaker 1: there who speaks Gaelic let us know how to say

619
00:30:41,600 --> 00:30:45,120
Speaker 1: space being in Gaelic. So this is a fun object

620
00:30:45,240 --> 00:30:49,600
Speaker 1: because it's in orbit technically around the Sun, but it's

621
00:30:49,840 --> 00:30:52,640
Speaker 1: ring resonance with the Earth. This is something maybe people

622
00:30:52,640 --> 00:30:55,440
Speaker 1: haven't realized that, like things that are orbiting the Sun

623
00:30:55,480 --> 00:30:58,920
Speaker 1: are also interacting with each other. Right, our orbit around

624
00:30:58,960 --> 00:31:01,160
Speaker 1: the Sun is mostly a big lips and it's dominated

625
00:31:01,160 --> 00:31:03,240
Speaker 1: by the Sun. The shape of that lips is mostly

626
00:31:03,240 --> 00:31:07,040
Speaker 1: controlled by the gravitational power of the Sun. But there

627
00:31:07,040 --> 00:31:09,880
Speaker 1: are other things also orbiting with us, and they tug

628
00:31:09,920 --> 00:31:12,360
Speaker 1: on us, they pull on us, and they can change

629
00:31:12,400 --> 00:31:15,440
Speaker 1: our orbit. And sometimes you get two objects and what

630
00:31:15,480 --> 00:31:17,960
Speaker 1: you call a resonance, which means that they are very

631
00:31:18,000 --> 00:31:20,920
Speaker 1: regularly tugging on each other in a systematic way that

632
00:31:21,040 --> 00:31:23,560
Speaker 1: changes both of their orbits and makes it stable, so that,

633
00:31:23,600 --> 00:31:26,680
Speaker 1: for example, they will like meet two or four times

634
00:31:26,840 --> 00:31:29,480
Speaker 1: while going around the Sun, depending on their relative speed,

635
00:31:29,640 --> 00:31:32,120
Speaker 1: and nudge each other in just the right way. So,

636
00:31:32,160 --> 00:31:35,240
Speaker 1: for example, Saturday and Jupiter are both really really powerful

637
00:31:35,480 --> 00:31:37,920
Speaker 1: and they're in an orbital residence with each other. So

638
00:31:38,040 --> 00:31:40,440
Speaker 1: this is an object that's moving around the Sun, but

639
00:31:40,480 --> 00:31:44,480
Speaker 1: it's in resonance with the Earth, so it's strongly influenced

640
00:31:44,480 --> 00:31:47,400
Speaker 1: by the Earth's gravity. But does it does it orbit

641
00:31:47,440 --> 00:31:49,560
Speaker 1: in the same shape the Moon duns? So how is

642
00:31:49,600 --> 00:31:53,040
Speaker 1: an orbit and a resonance different? So this thing moves

643
00:31:53,120 --> 00:31:55,840
Speaker 1: around the Sun, you know, but so does the Moon.

644
00:31:56,000 --> 00:31:58,240
Speaker 1: Right if you tracked the moon. The Moon goes around

645
00:31:58,240 --> 00:32:00,680
Speaker 1: the Sun. The Earth goes around the Sun one but

646
00:32:00,800 --> 00:32:04,320
Speaker 1: the Moon is gravitationally mostly bound to the Earth. This

647
00:32:04,360 --> 00:32:08,959
Speaker 1: thing is primarily mostly bound to the Sun, but because

648
00:32:09,000 --> 00:32:11,760
Speaker 1: of the influence of the Earth, if you look at

649
00:32:11,800 --> 00:32:13,960
Speaker 1: its orbit from the Earth, it looks like it makes

650
00:32:14,000 --> 00:32:18,120
Speaker 1: a bean shaped motion around the Earth. Like if you

651
00:32:18,160 --> 00:32:20,320
Speaker 1: put the Earth, if you're sending of your reference frame

652
00:32:20,360 --> 00:32:22,680
Speaker 1: and you plot where the space being is and you

653
00:32:22,800 --> 00:32:25,200
Speaker 1: like take data points from day to day and imagine

654
00:32:25,200 --> 00:32:28,000
Speaker 1: where it is. It makes a bean shape all the

655
00:32:28,000 --> 00:32:30,240
Speaker 1: way around the Earth. So does that mean it doesn't

656
00:32:30,320 --> 00:32:33,280
Speaker 1: quite fit the definition? Because like do orbits need to

657
00:32:33,320 --> 00:32:37,200
Speaker 1: be elliptical and not not being shaped? It means that

658
00:32:37,240 --> 00:32:40,080
Speaker 1: there's not really a clear distinction. We have a three

659
00:32:40,120 --> 00:32:42,640
Speaker 1: body system. We have the Sun, we have the Earth,

660
00:32:42,760 --> 00:32:45,240
Speaker 1: and we have the space being, and they're all tugging

661
00:32:45,280 --> 00:32:48,040
Speaker 1: on each other. And so to ask the question like

662
00:32:48,440 --> 00:32:51,280
Speaker 1: what is the space being orbiting? Is it orbiting the Earth?

663
00:32:51,360 --> 00:32:54,160
Speaker 1: Is it orbiting just the Sun, doesn't have a clear

664
00:32:54,240 --> 00:32:57,400
Speaker 1: precise answer unless you define an arbitrary distinction. But there

665
00:32:57,520 --> 00:33:00,800
Speaker 1: is no natural distinction between these two scenarios. Is like

666
00:33:00,840 --> 00:33:03,840
Speaker 1: a smooth continuum of being like the Moon where you're

667
00:33:03,920 --> 00:33:07,560
Speaker 1: very clearly disorbiting the Earth and being like Mercury, where

668
00:33:07,600 --> 00:33:11,240
Speaker 1: you're very clearly disorbiting the Sun. And then these quasi

669
00:33:11,440 --> 00:33:14,920
Speaker 1: satellites of Earth that are very clearly affected by Earth

670
00:33:14,960 --> 00:33:17,640
Speaker 1: and sort of moving around Earth as they move around

671
00:33:17,640 --> 00:33:20,240
Speaker 1: the Sun. And that's what the space bean is. It's

672
00:33:20,280 --> 00:33:23,960
Speaker 1: a quasi satellite of the Earth. All right, So two things. One,

673
00:33:24,480 --> 00:33:26,479
Speaker 1: every time you say space being I'm going to continue

674
00:33:26,480 --> 00:33:28,560
Speaker 1: to chuckle. I don't think I'm gonna stop doing that,

675
00:33:28,640 --> 00:33:31,920
Speaker 1: because it's just funny and cute and too you know,

676
00:33:31,920 --> 00:33:34,320
Speaker 1: I feel like it would be really nice in science

677
00:33:34,360 --> 00:33:37,880
Speaker 1: classes if like, how hard it is to do these

678
00:33:37,880 --> 00:33:41,040
Speaker 1: definitions and how so few things fit into these definitions

679
00:33:41,120 --> 00:33:42,760
Speaker 1: was sort of made more clear, and maybe they do

680
00:33:42,840 --> 00:33:45,280
Speaker 1: that in school today. It constantly blows my mind how

681
00:33:45,360 --> 00:33:48,480
Speaker 1: much I think that we have the world bend nicely.

682
00:33:49,120 --> 00:33:52,320
Speaker 1: But everything breaks the bins. Everything breaks the bins because

683
00:33:52,360 --> 00:33:55,640
Speaker 1: the world is continuous, right, and it's huge, and so

684
00:33:55,680 --> 00:33:58,160
Speaker 1: there's always going to be an example of something in between.

685
00:33:58,200 --> 00:34:02,000
Speaker 1: These crisp distinctions are are our artificial way to try

686
00:34:02,000 --> 00:34:04,640
Speaker 1: to impose order on the universe. And back when we

687
00:34:04,680 --> 00:34:08,280
Speaker 1: hadn't seen so many things, those gaps might have seen meaningful.

688
00:34:08,480 --> 00:34:10,560
Speaker 1: But as we keep looking at the universe, we find

689
00:34:10,560 --> 00:34:12,960
Speaker 1: stuff that feels in those gaps, and you know, the

690
00:34:13,000 --> 00:34:15,160
Speaker 1: same must be true in biology, right, that's what the

691
00:34:15,239 --> 00:34:17,880
Speaker 1: duck bill platypus is. Right, It's like, hold on a second,

692
00:34:18,239 --> 00:34:20,719
Speaker 1: what do you mean mammals? You know, right, right, it's

693
00:34:20,800 --> 00:34:22,880
Speaker 1: nature's way of being, like, you cannot put me in

694
00:34:22,880 --> 00:34:26,560
Speaker 1: a box. Yeah, so that's the space being. Also, I'm

695
00:34:26,560 --> 00:34:28,239
Speaker 1: saying the space being because it is fun to say,

696
00:34:28,360 --> 00:34:30,320
Speaker 1: and because I'm trying to avoid having to pronounce the

697
00:34:30,360 --> 00:34:32,960
Speaker 1: actual name of the thing. Yeah. No, sure, that makes sense,

698
00:34:33,160 --> 00:34:34,880
Speaker 1: It's okay. So here's what I want to know. So

699
00:34:35,080 --> 00:34:39,120
Speaker 1: we're not taught that the space being is a moon

700
00:34:39,320 --> 00:34:41,480
Speaker 1: in school, or at least I wasn't. So if you

701
00:34:41,520 --> 00:34:44,960
Speaker 1: were to walk into a random astronomer's office at some

702
00:34:45,120 --> 00:34:48,880
Speaker 1: university and ask them does the space being count as

703
00:34:48,920 --> 00:34:51,480
Speaker 1: a moon? Are they gonna like roll their eyes and

704
00:34:51,520 --> 00:34:53,320
Speaker 1: be like not this again. Or are they going to

705
00:34:53,440 --> 00:34:56,480
Speaker 1: be like, oh, that's a really interesting question, Like how

706
00:34:56,480 --> 00:35:01,280
Speaker 1: does the astronomy community do this question? That's a great question.

707
00:35:01,320 --> 00:35:03,080
Speaker 1: I bet that half of them would roll our eyes

708
00:35:03,120 --> 00:35:05,319
Speaker 1: and half of them would be like, you know, I

709
00:35:05,360 --> 00:35:08,600
Speaker 1: was on the committee that decided what a quasi satellite is,

710
00:35:08,640 --> 00:35:10,680
Speaker 1: and I have a very strong opinion about it, because

711
00:35:10,719 --> 00:35:12,920
Speaker 1: you know, they get hotheaded about this stuff, right, And

712
00:35:12,920 --> 00:35:14,960
Speaker 1: you will now sit for three hours while I explain

713
00:35:15,000 --> 00:35:18,600
Speaker 1: the difference to you and you regret asking immediately. Yeah,

714
00:35:18,640 --> 00:35:21,279
Speaker 1: And sometimes I wonder, like what does it matter? You know,

715
00:35:21,360 --> 00:35:23,520
Speaker 1: people argue about whether Pluto is a planet or a

716
00:35:23,600 --> 00:35:26,680
Speaker 1: dwarf planet, like, what are the consequences? Why does anybody

717
00:35:26,719 --> 00:35:29,760
Speaker 1: really care? We're just making these names up. It doesn't

718
00:35:29,840 --> 00:35:32,960
Speaker 1: change what Pluto is. It's not like Pluto shrinks if

719
00:35:32,960 --> 00:35:36,160
Speaker 1: we call it a dwarf planet or grows in importance

720
00:35:36,239 --> 00:35:38,160
Speaker 1: if we call it a real planet. These are just

721
00:35:38,239 --> 00:35:41,600
Speaker 1: our arbitrary categorizations of the universe. So the affect how

722
00:35:41,640 --> 00:35:44,640
Speaker 1: we think and how we talk, but really it's it's inconsequential.

723
00:35:44,719 --> 00:35:46,000
Speaker 1: You know. I can see why it would matter to

724
00:35:46,000 --> 00:35:48,000
Speaker 1: you if you are an astronomer, because maybe it affects

725
00:35:48,000 --> 00:35:50,600
Speaker 1: the way you model things based on how these definitions

726
00:35:50,640 --> 00:35:53,080
Speaker 1: fall out. But I imagine to the lay public it's like,

727
00:35:53,160 --> 00:35:56,920
Speaker 1: what are we paying these people for. That's a good point.

728
00:35:57,320 --> 00:35:59,600
Speaker 1: That's a good point. And so we have this thing

729
00:35:59,640 --> 00:36:02,000
Speaker 1: that said the moons to the quasi satellite, and that's

730
00:36:02,040 --> 00:36:04,040
Speaker 1: just one example. You know, there are lots of these

731
00:36:04,080 --> 00:36:06,800
Speaker 1: things that are sort of loosely bound to the Earth

732
00:36:07,280 --> 00:36:10,120
Speaker 1: orbiting the Sun that can be fairly small, like this

733
00:36:10,200 --> 00:36:12,839
Speaker 1: thing is only five kilometers in diameter. As you get

734
00:36:12,920 --> 00:36:15,640
Speaker 1: smaller and smaller, there are many many more of these things.

735
00:36:15,680 --> 00:36:17,720
Speaker 1: Some of them are more loosely bound to the Earth.

736
00:36:18,040 --> 00:36:19,799
Speaker 1: But you know, if you're gonna call this thing a moon,

737
00:36:19,880 --> 00:36:22,040
Speaker 1: then you've got to call all those other little things

738
00:36:22,120 --> 00:36:25,000
Speaker 1: moons also, So if you're gonna open the door that wide,

739
00:36:25,040 --> 00:36:27,120
Speaker 1: then Earth is going to have a lot of little moons,

740
00:36:27,239 --> 00:36:32,200
Speaker 1: and high school astronomy becomes totally untenable. And unfortunately, it

741
00:36:32,200 --> 00:36:34,040
Speaker 1: doesn't change what it looks like in the sky, right,

742
00:36:34,080 --> 00:36:35,919
Speaker 1: You can't look up in the sky and see this thing.

743
00:36:36,200 --> 00:36:39,480
Speaker 1: The closest it ever comes to Earth is like seven

744
00:36:39,520 --> 00:36:43,000
Speaker 1: and a half million miles away, which is thirty times

745
00:36:43,160 --> 00:36:46,480
Speaker 1: further away from the Earth than our moon is. Plus,

746
00:36:46,520 --> 00:36:48,839
Speaker 1: of course it's super tiny, so you have almost no

747
00:36:48,920 --> 00:36:51,799
Speaker 1: change of spotting this thing. It was difficult for astronomers

748
00:36:51,840 --> 00:36:53,640
Speaker 1: to even see it in the first place. It was

749
00:36:53,640 --> 00:36:55,879
Speaker 1: only discovered in the last twenty years. Is it safe

750
00:36:55,920 --> 00:36:58,200
Speaker 1: to assume that it's center of masses within the Earth

751
00:36:58,320 --> 00:37:00,280
Speaker 1: or the center of mass for the two bodies falls

752
00:37:00,280 --> 00:37:03,719
Speaker 1: within Earth? Absolutely? Yeah, because the Earth totally dominates this

753
00:37:03,760 --> 00:37:05,600
Speaker 1: thing when it comes to mass. This thing is only

754
00:37:05,640 --> 00:37:07,759
Speaker 1: five kilometers in diameter, and it's just a big chunk

755
00:37:07,760 --> 00:37:10,440
Speaker 1: of rock, and so the Earth dwarfs this thing. Okay,

756
00:37:10,440 --> 00:37:12,800
Speaker 1: even though it's super far away, it still works. Okay,

757
00:37:12,920 --> 00:37:15,800
Speaker 1: that's our like best candidates, is there like a second

758
00:37:15,800 --> 00:37:18,319
Speaker 1: best candidate. There's something else which I think is super fun,

759
00:37:18,480 --> 00:37:22,759
Speaker 1: which astronomers and science communicators called a temporary moon for

760
00:37:22,800 --> 00:37:25,680
Speaker 1: a while. And this is a weird object which at

761
00:37:25,719 --> 00:37:28,680
Speaker 1: the end of last year sort of swooped in from

762
00:37:28,680 --> 00:37:32,319
Speaker 1: deep space and orbiting the Earth a couple of times,

763
00:37:32,400 --> 00:37:34,480
Speaker 1: and people are like, oh, what is this thing? It

764
00:37:34,560 --> 00:37:36,520
Speaker 1: was like only forty ft long, and it has this

765
00:37:36,640 --> 00:37:40,160
Speaker 1: strange cylindrical shape, and they spotted it on his telescope

766
00:37:40,400 --> 00:37:42,160
Speaker 1: and they're like, wait a second, what is this thing?

767
00:37:42,600 --> 00:37:45,440
Speaker 1: And it looks like a piece of a rocket. What

768
00:37:45,960 --> 00:37:49,120
Speaker 1: it's space debris. It's space debris. And so it turns

769
00:37:49,160 --> 00:37:51,239
Speaker 1: out this is a long lost piece of an ill

770
00:37:51,360 --> 00:37:55,200
Speaker 1: faded NASA mission. There was this mission in nineteen sixty

771
00:37:55,239 --> 00:37:58,680
Speaker 1: six called Surveyor two. Is a robotic spacecraft that was

772
00:37:58,719 --> 00:38:00,640
Speaker 1: going to go land on the Moon and it was

773
00:38:00,640 --> 00:38:03,680
Speaker 1: going to go explore the Moon, etcetera. But mid course

774
00:38:03,760 --> 00:38:06,279
Speaker 1: there was a failure in the sort of ballistics and

775
00:38:06,320 --> 00:38:09,560
Speaker 1: the trajection and they lost contact with the craft and

776
00:38:09,640 --> 00:38:12,200
Speaker 1: one of the thrusters failed to ignite, and so basically

777
00:38:12,239 --> 00:38:14,279
Speaker 1: they lost this thing. Part of it crashed on the Moon,

778
00:38:14,560 --> 00:38:16,719
Speaker 1: and part of it just like tumbled out into deep

779
00:38:16,719 --> 00:38:19,880
Speaker 1: space sort of lost, they thought forever. And so this

780
00:38:19,920 --> 00:38:23,040
Speaker 1: thing has been like out there in space for you

781
00:38:23,080 --> 00:38:28,040
Speaker 1: know what, seventy years, almost bouncing around, swooshing around, and

782
00:38:28,160 --> 00:38:32,000
Speaker 1: somehow it ended up coming back to Earth. That's crazy,

783
00:38:32,239 --> 00:38:34,319
Speaker 1: first of all, I think it's more like fifty years though, right,

784
00:38:34,360 --> 00:38:37,879
Speaker 1: But like, it's amazing that we have that much resolution

785
00:38:38,200 --> 00:38:40,920
Speaker 1: that we could find it again. It's really incredible. But

786
00:38:41,000 --> 00:38:43,640
Speaker 1: you know, we are monitoring stuff that comes close to Earth,

787
00:38:43,800 --> 00:38:45,680
Speaker 1: and we're looking for stuff that's sort of like tumbling

788
00:38:45,719 --> 00:38:48,200
Speaker 1: towards the Earth. This is a pretty small object though

789
00:38:48,440 --> 00:38:50,960
Speaker 1: that it's also a weird shape. Right. If you're looking

790
00:38:51,000 --> 00:38:52,879
Speaker 1: out in the space and you see this forty ft

791
00:38:52,920 --> 00:38:56,759
Speaker 1: long cylindrical object, my first guess is gonna be like aliens, right,

792
00:38:57,200 --> 00:38:59,480
Speaker 1: And so how disappointed to look at it and then see,

793
00:38:59,520 --> 00:39:03,239
Speaker 1: like you say, written down the side, it's just our

794
00:39:03,320 --> 00:39:07,160
Speaker 1: old trash. But it's fascinating. People have done a study

795
00:39:07,200 --> 00:39:09,360
Speaker 1: to figure out like what happened to it, and it

796
00:39:09,440 --> 00:39:11,759
Speaker 1: turns out that when it tumbled out into space. It

797
00:39:11,800 --> 00:39:15,400
Speaker 1: was very gently pushed further into space by the pressure

798
00:39:15,480 --> 00:39:18,799
Speaker 1: of sunlight. We talked about this on the podcast, that

799
00:39:18,840 --> 00:39:21,879
Speaker 1: you could build a spaceship that sails on light. It's

800
00:39:21,880 --> 00:39:24,600
Speaker 1: called a solar sail. Just have a huge sheet of

801
00:39:24,640 --> 00:39:27,200
Speaker 1: material and the photons from the sun when they hit

802
00:39:27,280 --> 00:39:29,839
Speaker 1: it are going to transfer their momentum to that, just

803
00:39:29,880 --> 00:39:33,640
Speaker 1: like wind on Earth transfers its momentum to a sail

804
00:39:33,719 --> 00:39:37,040
Speaker 1: on a sailboat. And so that's like by design. But here,

805
00:39:37,040 --> 00:39:39,279
Speaker 1: of course, it's just a rocket tumbling in space, was

806
00:39:39,440 --> 00:39:43,440
Speaker 1: very gently, over decades and decades pushed deeper out into space.

807
00:39:43,560 --> 00:39:46,919
Speaker 1: Are you familiar with Project Westward? No? Tell me, Oh

808
00:39:46,920 --> 00:39:48,880
Speaker 1: my gosh. So the idea here was so this was

809
00:39:48,920 --> 00:39:51,480
Speaker 1: like during the Cold War, and the US was worried

810
00:39:51,480 --> 00:39:53,759
Speaker 1: that they would lose their ability to communicate with other

811
00:39:53,880 --> 00:39:57,640
Speaker 1: nations if our undersea cables got cut by the Soviets,

812
00:39:58,239 --> 00:40:00,399
Speaker 1: and so in that case we would have to rely

813
00:40:00,520 --> 00:40:02,920
Speaker 1: on sending radio waves up and we would have to

814
00:40:02,920 --> 00:40:05,239
Speaker 1: hope that they would bounce off the ionosphere. But that's

815
00:40:05,239 --> 00:40:08,600
Speaker 1: sort of a not super reliable way of sending radio communications,

816
00:40:08,719 --> 00:40:10,799
Speaker 1: and so I think it was m i T came

817
00:40:10,880 --> 00:40:13,080
Speaker 1: up with the solution where they were like, well, we

818
00:40:13,160 --> 00:40:17,160
Speaker 1: could be sure that the ionosphere would have stuff that

819
00:40:17,160 --> 00:40:20,120
Speaker 1: would bounce the radio waves back if we put up

820
00:40:20,560 --> 00:40:26,520
Speaker 1: over four hundred million copper needles. That's a great idea, right,

821
00:40:26,640 --> 00:40:29,120
Speaker 1: And so the argument was that you would put these

822
00:40:29,160 --> 00:40:31,680
Speaker 1: needles up and it would give us some information about

823
00:40:31,680 --> 00:40:33,680
Speaker 1: how well this was gonna work. But in about two

824
00:40:33,719 --> 00:40:37,400
Speaker 1: to three years, the combination of gravity and the sun

825
00:40:37,800 --> 00:40:41,719
Speaker 1: pushing these needles back into the atmosphere would clear everything out,

826
00:40:42,280 --> 00:40:44,920
Speaker 1: clear everything out. Does that mean these copper needles come

827
00:40:45,120 --> 00:40:48,000
Speaker 1: raining back down to the service to impale people. Well,

828
00:40:48,280 --> 00:40:50,960
Speaker 1: they do start raining back down towards Earth, but they're

829
00:40:51,000 --> 00:40:53,160
Speaker 1: like literally only a couple of maybe centimeters long, like

830
00:40:53,200 --> 00:40:55,560
Speaker 1: maybe two centimeters or something. These aren't huge, and that's

831
00:40:55,560 --> 00:40:58,759
Speaker 1: why they needed four million of them. That sounds like

832
00:40:58,800 --> 00:41:02,200
Speaker 1: approximately the size is of a bullet. You're talking about

833
00:41:02,400 --> 00:41:05,120
Speaker 1: space bullets raining down on the Earth. But that would

834
00:41:05,120 --> 00:41:08,480
Speaker 1: definitely burn up before it hits Earth, right, right, Yes,

835
00:41:08,560 --> 00:41:11,520
Speaker 1: of course I think so. Yeah, so our atmosphere is

836
00:41:11,520 --> 00:41:14,480
Speaker 1: like a bulletproof vest. Yes, thank you atmosphere. But so

837
00:41:14,560 --> 00:41:16,280
Speaker 1: the first one that they shot up there, it didn't

838
00:41:16,320 --> 00:41:18,160
Speaker 1: deploy the right way, so a bunch of these needles

839
00:41:18,160 --> 00:41:20,839
Speaker 1: clumped instead of spreading nicely, and so some of these

840
00:41:20,920 --> 00:41:24,640
Speaker 1: clumps fifty years later are still tracked as space debris

841
00:41:25,000 --> 00:41:27,759
Speaker 1: because the clumps didn't de orbit the way that they

842
00:41:27,760 --> 00:41:29,480
Speaker 1: thought they would. And then they did a second shot,

843
00:41:29,520 --> 00:41:32,080
Speaker 1: and the second shot dispersed and they were able to confirm, yes,

844
00:41:32,120 --> 00:41:35,399
Speaker 1: the radio waves bounced back more when we have supplemented

845
00:41:35,400 --> 00:41:37,719
Speaker 1: the ionosphere with all of these needles. But then we

846
00:41:37,760 --> 00:41:39,839
Speaker 1: had to go to the United Nations and promise we

847
00:41:39,840 --> 00:41:42,680
Speaker 1: were going to stop messing up the space environment and

848
00:41:42,719 --> 00:41:45,160
Speaker 1: that we were going to consult people from here on out.

849
00:41:45,480 --> 00:41:47,640
Speaker 1: And one of the articles of the Outer Space Treaty

850
00:41:47,680 --> 00:41:50,960
Speaker 1: actually requires people to do consultations. And that was motivated

851
00:41:51,000 --> 00:41:54,399
Speaker 1: by Project Westward, because what the heck is the US doing?

852
00:41:54,600 --> 00:41:58,240
Speaker 1: So anyway, tangent related to the Sun pushing things back

853
00:41:58,320 --> 00:42:01,440
Speaker 1: into orbits or sorry, back into the atmosphere. Yeah, and

854
00:42:01,440 --> 00:42:04,040
Speaker 1: we have a whole fun podcast episode about space junk

855
00:42:04,360 --> 00:42:07,320
Speaker 1: and how dangerous it is and that's all smashing into itself.

856
00:42:07,360 --> 00:42:09,480
Speaker 1: And if we don't get this stuff under control, all

857
00:42:09,520 --> 00:42:11,920
Speaker 1: of space might be useless to us. We might be

858
00:42:12,239 --> 00:42:14,960
Speaker 1: trapped down here on Earth because we'd be surrounded by

859
00:42:14,960 --> 00:42:17,800
Speaker 1: our own garbage. So check out that episode if you're interested.

860
00:42:17,920 --> 00:42:21,200
Speaker 1: But this is one particularly interesting object, and it came

861
00:42:21,320 --> 00:42:25,400
Speaker 1: in November twenty and made a few large loops around

862
00:42:25,400 --> 00:42:27,000
Speaker 1: the Earth. And so that's why they called this sort

863
00:42:27,040 --> 00:42:29,960
Speaker 1: of like a temporary moon, because even though it was

864
00:42:30,040 --> 00:42:32,920
Speaker 1: lost in deep space, somehow it ended up close enough

865
00:42:32,960 --> 00:42:35,600
Speaker 1: for the Earth to grab it again and loop around.

866
00:42:35,800 --> 00:42:38,360
Speaker 1: But it wasn't a stable orbit, which is really fascinating.

867
00:42:38,440 --> 00:42:40,120
Speaker 1: It was like stable enough to loop around a few

868
00:42:40,160 --> 00:42:42,920
Speaker 1: times and then get tossed back out into space. So

869
00:42:43,000 --> 00:42:46,880
Speaker 1: in March continued his journey and is now back into

870
00:42:46,920 --> 00:42:49,840
Speaker 1: deep space somewhere. WHOA. So, so was this like a

871
00:42:49,920 --> 00:42:53,080
Speaker 1: sycom angle for getting people interested in this, because it

872
00:42:53,080 --> 00:42:56,719
Speaker 1: seems like because it was artificial, it shouldn't count as

873
00:42:56,719 --> 00:42:59,280
Speaker 1: a moon at all, not a temporary moon. It shouldn't

874
00:42:59,280 --> 00:43:01,719
Speaker 1: be a moon. Or do different people use different definitions

875
00:43:01,719 --> 00:43:03,400
Speaker 1: than the one that we settled upon at the beginning

876
00:43:03,440 --> 00:43:05,840
Speaker 1: of the episode, Yeah, exactly. I think this was just

877
00:43:05,880 --> 00:43:09,640
Speaker 1: a clickbait moon, not really by any definition. If you're

878
00:43:09,640 --> 00:43:12,400
Speaker 1: going to require that moons be natural, may not be

879
00:43:13,000 --> 00:43:16,040
Speaker 1: manufactured by humanity. Then this is definitely not a mood.

880
00:43:16,239 --> 00:43:18,360
Speaker 1: But it's cool that we capture something from deep space

881
00:43:18,400 --> 00:43:21,040
Speaker 1: and it orbited us a little while before going back

882
00:43:21,160 --> 00:43:24,479
Speaker 1: out into the dark deep emptiness. Yeah, no, that's super cool.

883
00:43:24,600 --> 00:43:26,640
Speaker 1: All right, So let's take our second break before we

884
00:43:26,680 --> 00:43:29,440
Speaker 1: start to talk a bit more about moons on planets

885
00:43:29,440 --> 00:43:44,000
Speaker 1: other than our own. Okay, so we've talked a bit.

886
00:43:44,040 --> 00:43:47,560
Speaker 1: How about how Earth has one for sure moon and

887
00:43:47,600 --> 00:43:52,359
Speaker 1: a couple maybe moons, quasi moons, quasi moons. Right, tell

888
00:43:52,360 --> 00:43:54,160
Speaker 1: me a bit more about what else is typical in

889
00:43:54,200 --> 00:43:56,560
Speaker 1: the Solar System. How many moons do the other planets have.

890
00:43:56,760 --> 00:43:59,640
Speaker 1: It's really interesting because the Earth, as we were saying,

891
00:43:59,840 --> 00:44:03,720
Speaker 1: is really weird, Like having a really big moon is weird. Also,

892
00:44:04,040 --> 00:44:07,400
Speaker 1: having just one moon is weird. So the eight planets

893
00:44:07,400 --> 00:44:09,399
Speaker 1: in the Solar System, of course, the Earth has one moon.

894
00:44:09,640 --> 00:44:13,200
Speaker 1: Two of the planets have no moons, Mercury and Venus,

895
00:44:13,800 --> 00:44:17,560
Speaker 1: and the other five planets have two hundred and four

896
00:44:17,640 --> 00:44:21,400
Speaker 1: moons in between them. So that's really fascinating and you

897
00:44:21,440 --> 00:44:24,319
Speaker 1: might wonder like, well, why do Mercury and Venus have

898
00:44:24,400 --> 00:44:28,080
Speaker 1: no moons? And the reason is that they're so close

899
00:44:28,120 --> 00:44:31,160
Speaker 1: to the Sun. The Sun is this like really terrible

900
00:44:31,400 --> 00:44:35,960
Speaker 1: overwhelming gravitational force and it tugs on things. We talked

901
00:44:35,960 --> 00:44:39,040
Speaker 1: to the program before about tidal forces. The closer you

902
00:44:39,080 --> 00:44:41,200
Speaker 1: are to the Sun, the more it tugs on you.

903
00:44:41,600 --> 00:44:43,680
Speaker 1: So if you're an object, it's not just like a point.

904
00:44:43,800 --> 00:44:45,799
Speaker 1: If you have like an extent to you, and the

905
00:44:45,840 --> 00:44:48,120
Speaker 1: Sun is going to tug harder on the bit that's

906
00:44:48,120 --> 00:44:51,080
Speaker 1: closer and not as hard on the bid that's further away,

907
00:44:51,280 --> 00:44:53,279
Speaker 1: and that's an effective force on you. So the Sun is,

908
00:44:53,320 --> 00:44:56,440
Speaker 1: for example, squeezing mercury and venus all the time. It's

909
00:44:56,480 --> 00:44:58,799
Speaker 1: pulling on them, and that makes it very hard for

910
00:44:58,840 --> 00:45:02,520
Speaker 1: them to have any in a stable orbit around them. Basically,

911
00:45:02,520 --> 00:45:04,360
Speaker 1: if they have a moon, the Sun is going to

912
00:45:04,440 --> 00:45:07,040
Speaker 1: steal it when it swoops around the planet on the

913
00:45:07,040 --> 00:45:09,400
Speaker 1: close side. So here I'm finding that I want to

914
00:45:09,440 --> 00:45:11,759
Speaker 1: ask you if that means in other Solar systems, the

915
00:45:12,000 --> 00:45:14,040
Speaker 1: close planets don't have moons. But I'm jumping if I

916
00:45:14,080 --> 00:45:16,239
Speaker 1: do that, aren't I We don't know the answer to

917
00:45:16,239 --> 00:45:18,440
Speaker 1: that question yet. We'll talk about that in a minute,

918
00:45:18,600 --> 00:45:21,080
Speaker 1: but yeah, it's a fascinating question. We know that in

919
00:45:21,239 --> 00:45:24,600
Speaker 1: our Solar system, the innermost planets Mercury and Venus have

920
00:45:24,760 --> 00:45:27,279
Speaker 1: no moons, and you know, that might be part of

921
00:45:27,320 --> 00:45:30,359
Speaker 1: the answer of why the Earth only has one moon

922
00:45:30,440 --> 00:45:32,440
Speaker 1: and it's a really big one. It might be that

923
00:45:32,600 --> 00:45:35,839
Speaker 1: anything else the Sun is basically going to steal, and

924
00:45:35,880 --> 00:45:38,200
Speaker 1: that we're only capable of having like either really big

925
00:45:38,200 --> 00:45:41,440
Speaker 1: moons or quasi moons that were sort of sharing with

926
00:45:41,560 --> 00:45:45,360
Speaker 1: the Sun. That might be the partial answer to that question. Interesting,

927
00:45:45,360 --> 00:45:47,560
Speaker 1: So we have the Sun to thank for the space being. Yeah,

928
00:45:47,719 --> 00:45:49,719
Speaker 1: the Sun is toasting our space being for us. But

929
00:45:49,760 --> 00:45:52,000
Speaker 1: then further out in the Solar system, there are lots

930
00:45:52,000 --> 00:45:55,120
Speaker 1: and lots of moons. You know, the other five planets

931
00:45:55,120 --> 00:45:58,320
Speaker 1: with moons have two hundred and four of these things combined,

932
00:45:58,760 --> 00:46:00,960
Speaker 1: you know, in Jupiter and sat And have like dozens

933
00:46:00,960 --> 00:46:04,320
Speaker 1: of them. And you know, Saturn has this crazy ring system,

934
00:46:04,360 --> 00:46:07,600
Speaker 1: and inside those rings are rocks that are big enough

935
00:46:07,640 --> 00:46:11,319
Speaker 1: to be considered moons. Sometimes they're called you know, moonlits,

936
00:46:11,400 --> 00:46:14,760
Speaker 1: sometimes are called minor moons. But there are all sorts

937
00:46:14,760 --> 00:46:16,960
Speaker 1: of things, and so the deeper you go out into

938
00:46:17,000 --> 00:46:19,799
Speaker 1: our Solar system, the more you find these objects that

939
00:46:19,840 --> 00:46:22,239
Speaker 1: have moons and lots and lots of moons. To do

940
00:46:22,360 --> 00:46:25,480
Speaker 1: any of the moons have moons. I wish they did

941
00:46:25,520 --> 00:46:27,200
Speaker 1: have moons. And what would you call that anyway? Would

942
00:46:27,320 --> 00:46:33,480
Speaker 1: that be like a moon moon or squared? That's a

943
00:46:33,480 --> 00:46:36,720
Speaker 1: great question. And so far we haven't found any moons

944
00:46:36,760 --> 00:46:40,400
Speaker 1: that have moons. And the reason is similar to why

945
00:46:40,400 --> 00:46:43,319
Speaker 1: Mercury doesn't have moons. If you're a moon, then you're

946
00:46:43,360 --> 00:46:45,640
Speaker 1: near a big planet, and that means that there are

947
00:46:45,640 --> 00:46:48,720
Speaker 1: tidal forces, and so it's pretty hard to hold onto

948
00:46:48,760 --> 00:46:50,960
Speaker 1: something and not have it gets slurred up and just

949
00:46:51,040 --> 00:46:54,719
Speaker 1: become another moon of the planet you're orbiting. So if

950
00:46:54,760 --> 00:46:57,359
Speaker 1: you're Io and you're orbiting Jupiter, right, Jupiter is an

951
00:46:57,480 --> 00:47:01,440
Speaker 1: enormous gravitational pull. The reason that Io is like hot inside,

952
00:47:01,480 --> 00:47:04,720
Speaker 1: it's because of Jupiter's tidal forces, and so anything orbiting

953
00:47:04,760 --> 00:47:07,040
Speaker 1: Io is just going to get pulled away. It's very

954
00:47:07,160 --> 00:47:10,560
Speaker 1: very hard to have a stable orbit. Although there's this

955
00:47:10,760 --> 00:47:14,239
Speaker 1: really crazy moon of Saturn. This moon is called Rhea,

956
00:47:14,680 --> 00:47:18,040
Speaker 1: and recently they've spotted some stuff in orbit around Rhea,

957
00:47:18,239 --> 00:47:21,760
Speaker 1: maybe sort of like these very small particles. It almost

958
00:47:21,760 --> 00:47:25,960
Speaker 1: looks like this moon of Saturn has its own ring system.

959
00:47:26,239 --> 00:47:29,279
Speaker 1: What I know, isn't that cool? I never thought about

960
00:47:29,280 --> 00:47:32,280
Speaker 1: like a moon with rings around. It is pretty cool.

961
00:47:32,600 --> 00:47:35,320
Speaker 1: That's awesome. So so how if it can't have moons,

962
00:47:35,360 --> 00:47:38,239
Speaker 1: how does it manage to maintain its rings? Well, the

963
00:47:38,280 --> 00:47:41,120
Speaker 1: reason you sometimes have rings instead of moons are because

964
00:47:41,160 --> 00:47:44,040
Speaker 1: of tidal forces. Basically, rings are moons that have been

965
00:47:44,080 --> 00:47:47,160
Speaker 1: torn apart by tidal forces. And so it might be

966
00:47:47,200 --> 00:47:49,160
Speaker 1: that there was an object there and then it got

967
00:47:49,160 --> 00:47:51,759
Speaker 1: sort of shredded by tidal forces, and what we're seeing

968
00:47:51,840 --> 00:47:54,560
Speaker 1: is something transient that these rings might not last for

969
00:47:54,719 --> 00:47:56,600
Speaker 1: very long. You know, by very long we mean on

970
00:47:56,719 --> 00:47:59,040
Speaker 1: astrophysical time scale. So they might be there a million

971
00:47:59,120 --> 00:48:01,360
Speaker 1: years or so. But if you leave the Solar system

972
00:48:01,360 --> 00:48:03,560
Speaker 1: and come back and five million, you might find that

973
00:48:03,600 --> 00:48:06,680
Speaker 1: they're not there anymore. Okay, so let's move out of

974
00:48:06,680 --> 00:48:08,799
Speaker 1: our solar system. What does this look like in other

975
00:48:08,840 --> 00:48:12,040
Speaker 1: solar system? So, for example, do the mercury and venus

976
00:48:12,080 --> 00:48:16,319
Speaker 1: equivalents and other solar systems lack moons like we see

977
00:48:16,360 --> 00:48:18,680
Speaker 1: in our solar system. It's such a good question and

978
00:48:18,719 --> 00:48:21,360
Speaker 1: one we just don't know the answer to yet because

979
00:48:21,640 --> 00:48:24,960
Speaker 1: we have never seen a moon in another solar system,

980
00:48:25,280 --> 00:48:28,040
Speaker 1: Like every moon that any human has ever seen has

981
00:48:28,160 --> 00:48:31,440
Speaker 1: only ever been in our solar system. Isn't that like

982
00:48:31,640 --> 00:48:34,960
Speaker 1: crazy and slightly frustrating. It's both of those things, And

983
00:48:35,000 --> 00:48:37,240
Speaker 1: it reveals to me, like just how often I assume

984
00:48:37,280 --> 00:48:39,440
Speaker 1: that science has figured out so many things that are

985
00:48:39,520 --> 00:48:42,400
Speaker 1: much harder than I apparently understand. So why do we

986
00:48:42,440 --> 00:48:44,360
Speaker 1: know that all these other solar systems have planets but

987
00:48:44,400 --> 00:48:46,560
Speaker 1: we don't know that they have moons? Well, moons are

988
00:48:46,680 --> 00:48:48,840
Speaker 1: much smaller, and they're just harder to see them planets.

989
00:48:49,200 --> 00:48:51,040
Speaker 1: You know, we now sort of take it for granted

990
00:48:51,040 --> 00:48:53,839
Speaker 1: that we can see planets around other stars, But that's

991
00:48:53,880 --> 00:48:57,040
Speaker 1: pretty recent. It was like that we started to be

992
00:48:57,040 --> 00:48:59,840
Speaker 1: able to really do this and spot planets and other soldiers.

993
00:49:00,400 --> 00:49:03,200
Speaker 1: Until then, we had never seen a planet around a

994
00:49:03,280 --> 00:49:07,160
Speaker 1: star that wasn't our star. We didn't know until then, if,

995
00:49:07,200 --> 00:49:10,400
Speaker 1: for example, our star was the only one that had planets,

996
00:49:10,440 --> 00:49:13,759
Speaker 1: we could have been like the weirdest star in the universe. Now,

997
00:49:13,800 --> 00:49:15,880
Speaker 1: of course, we know, because we've looked and we've seen

998
00:49:16,040 --> 00:49:17,919
Speaker 1: that lots and lots and lots of stars have lots

999
00:49:17,920 --> 00:49:19,920
Speaker 1: and lots of planets. We're also learning, of course, that

1000
00:49:19,920 --> 00:49:22,360
Speaker 1: our Solar system is weird in all sorts of interesting ways.

1001
00:49:22,520 --> 00:49:25,319
Speaker 1: But the problem is that the techniques we used to

1002
00:49:25,320 --> 00:49:28,640
Speaker 1: see those planets are better when the planets are large

1003
00:49:28,719 --> 00:49:31,120
Speaker 1: and when they're close to the Sun, and that makes

1004
00:49:31,160 --> 00:49:33,600
Speaker 1: it pretty hard to see moons, which tend to be

1005
00:49:33,719 --> 00:49:36,680
Speaker 1: small and further from the star. We haven't found any

1006
00:49:36,719 --> 00:49:39,800
Speaker 1: instances of a moon that's like huge or one of

1007
00:49:39,840 --> 00:49:41,840
Speaker 1: those instances where it's hard to determine which one is

1008
00:49:41,880 --> 00:49:43,680
Speaker 1: the planet and which one is the moon because they're

1009
00:49:43,680 --> 00:49:46,640
Speaker 1: both pretty big, and so there's no big things that

1010
00:49:46,680 --> 00:49:50,000
Speaker 1: break this rule. We haven't confirmed any moons and other

1011
00:49:50,000 --> 00:49:52,799
Speaker 1: solar systems are you're looking for the duck built platypus

1012
00:49:52,840 --> 00:49:55,719
Speaker 1: of moons out there somewhere No so far zero. There

1013
00:49:55,719 --> 00:49:59,080
Speaker 1: have been some candidates. People have some really clever ideas

1014
00:49:59,120 --> 00:50:02,319
Speaker 1: for how you might see moons around planets in other

1015
00:50:02,400 --> 00:50:05,480
Speaker 1: solar systems. Like one way that we see the planet

1016
00:50:05,800 --> 00:50:07,839
Speaker 1: is that the planet passes in front of the star

1017
00:50:08,320 --> 00:50:10,480
Speaker 1: makes like a little eclipse, it like dims the star

1018
00:50:10,600 --> 00:50:12,839
Speaker 1: a little bit. And if it does that several times,

1019
00:50:12,880 --> 00:50:14,520
Speaker 1: you can see a pattern, so you can get a

1020
00:50:14,560 --> 00:50:16,560
Speaker 1: sense for like, oh, this is really something that's passing

1021
00:50:16,600 --> 00:50:18,439
Speaker 1: in front of the star. It must be a planet. Now,

1022
00:50:18,480 --> 00:50:21,320
Speaker 1: if there's a moon around that planet and it's orbiting

1023
00:50:21,360 --> 00:50:24,120
Speaker 1: that planet. As it passes around the planet, it might

1024
00:50:24,400 --> 00:50:27,200
Speaker 1: add to that eclipse a little bit and then pass

1025
00:50:27,280 --> 00:50:29,680
Speaker 1: behind the planet and dip again. And so if you

1026
00:50:29,680 --> 00:50:33,280
Speaker 1: have really refined measurements, you might see these like wiggles

1027
00:50:33,320 --> 00:50:36,800
Speaker 1: on the wiggles that tell you that there's something going

1028
00:50:36,840 --> 00:50:40,040
Speaker 1: around that planet. And there are some cases where people

1029
00:50:40,080 --> 00:50:41,480
Speaker 1: look at the data and they're like, yeah, I think

1030
00:50:41,560 --> 00:50:44,120
Speaker 1: those are wiggles and wiggles, but other people analyze the

1031
00:50:44,160 --> 00:50:46,560
Speaker 1: same data and they're like, no, there's no evidence for that.

1032
00:50:46,719 --> 00:50:48,799
Speaker 1: So we're really at the edge of being able to

1033
00:50:48,840 --> 00:50:52,840
Speaker 1: detect XO moons. We haven't seen any yet. Well that's exciting, Like,

1034
00:50:52,880 --> 00:50:55,879
Speaker 1: hopefully in our lifetime we figure out how to do that. Well, yeah,

1035
00:50:55,960 --> 00:50:58,160
Speaker 1: hopefully in our lifetime. I mean, we're on the edge

1036
00:50:58,160 --> 00:51:00,280
Speaker 1: of learning so much about these other solars to times,

1037
00:51:00,280 --> 00:51:03,240
Speaker 1: like figuring out what's any atmosphere of those planets, seeing

1038
00:51:03,239 --> 00:51:05,680
Speaker 1: what moons there are. There was also a lot of excitement.

1039
00:51:05,680 --> 00:51:07,560
Speaker 1: I don't know if you remember about this one particular

1040
00:51:07,640 --> 00:51:11,560
Speaker 1: star called Tabby Star, which dimmed really weirdly all of

1041
00:51:11,600 --> 00:51:13,879
Speaker 1: a sudden, and people thought like, wait a second, what's

1042
00:51:13,880 --> 00:51:17,400
Speaker 1: blocking this star? Is this evidence of like an alien megastructure.

1043
00:51:17,640 --> 00:51:20,359
Speaker 1: Is somebody out there building a dison spear around this star,

1044
00:51:20,600 --> 00:51:22,600
Speaker 1: which was really fun and you know inspired, I'm sure

1045
00:51:22,600 --> 00:51:25,279
Speaker 1: a lot of science fiction novels. But it turns out

1046
00:51:25,320 --> 00:51:27,720
Speaker 1: that it was just like a big cloud of dust

1047
00:51:27,800 --> 00:51:30,880
Speaker 1: and debris. But it might be that, like, you know,

1048
00:51:30,960 --> 00:51:33,400
Speaker 1: there was a planet out there and it had a moon,

1049
00:51:33,640 --> 00:51:36,759
Speaker 1: and that moon got like tidally disrupted and torn up

1050
00:51:36,960 --> 00:51:39,360
Speaker 1: and ended up being this big cloud of stuff that

1051
00:51:39,440 --> 00:51:42,120
Speaker 1: partially blocked the star. So that might have been like,

1052
00:51:42,440 --> 00:51:45,840
Speaker 1: you know, evidence of the destruction of an excellent moon. WHOA,

1053
00:51:46,160 --> 00:51:48,919
Speaker 1: that's pretty cool. That's pretty cool. Yeah, But I'm looking

1054
00:51:48,960 --> 00:51:51,359
Speaker 1: forward to scientists figuring that out and so we can

1055
00:51:51,400 --> 00:51:54,440
Speaker 1: get a sense for like how unusual is it to

1056
00:51:54,560 --> 00:51:57,839
Speaker 1: have just like one big moon, How unusual is it

1057
00:51:57,880 --> 00:52:00,719
Speaker 1: to have inner planets with no moons? How weird is

1058
00:52:00,719 --> 00:52:03,360
Speaker 1: it to have huge gas giants with like a dozen moons.

1059
00:52:03,760 --> 00:52:06,160
Speaker 1: We ask these basic questions because we just don't know

1060
00:52:06,200 --> 00:52:08,040
Speaker 1: the answers, and really the only way to figure it

1061
00:52:08,040 --> 00:52:10,440
Speaker 1: out is to go out there and explore the universe

1062
00:52:10,520 --> 00:52:12,920
Speaker 1: and to like actually look with our eyeballs and our

1063
00:52:12,960 --> 00:52:15,759
Speaker 1: telescopes and get the answers. It's a cool time to

1064
00:52:15,800 --> 00:52:18,640
Speaker 1: be alive. It is a cool time to be alive. So, Kelly,

1065
00:52:18,640 --> 00:52:20,080
Speaker 1: what are you going to go back and tell your

1066
00:52:20,120 --> 00:52:23,279
Speaker 1: seven year old about how many moons the Earth has? Well,

1067
00:52:23,480 --> 00:52:25,640
Speaker 1: I think she's going to be super excited. She We've

1068
00:52:25,640 --> 00:52:28,080
Speaker 1: been talking to her about Apollo and the space race,

1069
00:52:28,080 --> 00:52:29,920
Speaker 1: and I think she'll be super excited to hear that

1070
00:52:30,000 --> 00:52:32,359
Speaker 1: one of those you know, boosters came back around again

1071
00:52:32,400 --> 00:52:34,600
Speaker 1: and is still floating in deep space. So I'll tell

1072
00:52:34,600 --> 00:52:37,160
Speaker 1: her about that, and I definitely think she's going to

1073
00:52:37,280 --> 00:52:40,759
Speaker 1: love that there's something called a space being or something

1074
00:52:40,800 --> 00:52:42,480
Speaker 1: we referred to as a space being because we can't

1075
00:52:42,480 --> 00:52:44,719
Speaker 1: pronounce its real name. I think she's going to get

1076
00:52:44,760 --> 00:52:46,880
Speaker 1: a total kick out of that information. What about you,

1077
00:52:46,920 --> 00:52:48,920
Speaker 1: what are you gonna tell your kids? Yeah, my kids

1078
00:52:48,960 --> 00:52:51,600
Speaker 1: also will tell them that there's weird stuff floating out there,

1079
00:52:52,000 --> 00:52:54,280
Speaker 1: and that in the end, it's all just sort of arbitrary.

1080
00:52:54,400 --> 00:52:56,320
Speaker 1: What we call a moon and what we call a

1081
00:52:56,400 --> 00:53:00,279
Speaker 1: quasi satellite is really just an arbitrary distinction, but that

1082
00:53:00,480 --> 00:53:03,480
Speaker 1: their questions are valuable questions, and that these really simple,

1083
00:53:03,560 --> 00:53:06,560
Speaker 1: basic questions about the universe are sometimes the most interesting,

1084
00:53:06,840 --> 00:53:10,400
Speaker 1: the hardest to answer and reveal something about you know,

1085
00:53:10,440 --> 00:53:12,879
Speaker 1: what we've thought about our place in the universe, what

1086
00:53:12,920 --> 00:53:15,080
Speaker 1: we think is natural, what we think is normal, what

1087
00:53:15,120 --> 00:53:18,600
Speaker 1: we think is typical, and it probably is really unusual.

1088
00:53:18,680 --> 00:53:22,040
Speaker 1: And that's somewhere out there there's an alien kid looking

1089
00:53:22,120 --> 00:53:24,560
Speaker 1: up at the sky and asking the alien mom, like,

1090
00:53:24,800 --> 00:53:27,080
Speaker 1: why do we have five moons? You know, it's just

1091
00:53:27,160 --> 00:53:29,760
Speaker 1: every planet to have five moons. I love that idea

1092
00:53:29,840 --> 00:53:32,640
Speaker 1: that we're all asking the same questions, but just very

1093
00:53:32,719 --> 00:53:35,560
Speaker 1: much separated. All right, So thank you very much everybody

1094
00:53:35,600 --> 00:53:38,680
Speaker 1: for going on this curiosity journey with us and listening

1095
00:53:38,680 --> 00:53:41,600
Speaker 1: to us talk about the number of moons around the Earth.

1096
00:53:41,840 --> 00:53:43,719
Speaker 1: If you have stuff you'd like to hear us talk about,

1097
00:53:43,760 --> 00:53:46,840
Speaker 1: please send them to us two questions at Daniel and

1098
00:53:47,000 --> 00:53:49,680
Speaker 1: Jorge dot com. Thanks again, Kelly for joining us today

1099
00:53:49,680 --> 00:53:51,680
Speaker 1: and thanks to all of you for tuning in. Thanks

1100
00:53:51,680 --> 00:54:00,960
Speaker 1: for having me. It was a lot of fun. Thanks

1101
00:54:00,960 --> 00:54:03,560
Speaker 1: for listening, and remember that Daniel and Jorge explained. The

1102
00:54:03,680 --> 00:54:06,759
Speaker 1: Universe is a production of I Heart Radio or more

1103
00:54:06,840 --> 00:54:10,200
Speaker 1: podcast from my Heart Radio visit the I Heart Radio app,

1104
00:54:10,480 --> 00:54:13,960
Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.