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Speaker 1: Hey, org, did you share a room with siblings when

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Speaker 1: you were a kid?

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Speaker 2: I did. I shared a room with my brother.

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Speaker 1: Ooh, And was that like cozy and fun for the

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Speaker 1: two of you? Or did you get on each other's nerves?

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Speaker 3: It was pretty fun. We get along pretty good. How

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Speaker 3: about you?

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Speaker 1: I shared a room with two brothers and there was

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Speaker 1: not a whole lot of coziness there. We got on

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Speaker 1: each other's nerves a lot.

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Speaker 2: Yikes. Sounds intense.

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Speaker 1: Yeah, I remember after one argument my mom telling us

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Speaker 1: if we couldn't get along, we'd have to live outside. Intense.

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Speaker 3: WHOA, sounds intense? But is that why you like camping

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Speaker 3: so much? Because you did end up outside in the tent?

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Speaker 3: That's that where your love of the stars came from.

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Speaker 3: This is your origin story. It's all because of your brother,

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Speaker 3: your nemesis or nemesi.

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Speaker 1: Is how I extracted something beautiful from a difficult story.

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Speaker 3: Sounds like a hallmark. We we know how you overcame,

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Speaker 3: sibling Riberry.

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Speaker 1: Depends on whether it ends well or not.

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Speaker 2: I guess only ends and one of you dies.

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Speaker 3: Hi am Jorhemick, cartoonist and the author of Oliver's Great

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Speaker 3: Big Universe.

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Speaker 1: Hi, I'm Daniel, I'm a particle physicist and a professor

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Speaker 1: at u C Irvine, and I've been totally eclipsed by

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Speaker 1: my younger brother.

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Speaker 3: Oh boy, is he a more shiny star or something.

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Speaker 1: He's taller than me, he's a professor at a fancier

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Speaker 1: university than I am. What else is there?

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Speaker 2: But does he have a podcast?

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Speaker 1: There you go. I don't know if he wants a podcast,

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Speaker 1: but yeah, that's a good point. I'm going to bring

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Speaker 1: that up at Thanksgiving.

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Speaker 3: Thanks You know, it's super hard to do a podcast,

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Speaker 3: or at least the start one. There's a high bar

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Speaker 3: for putting things on the internet. They don't just let

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Speaker 3: anyone post things on the internet, you know.

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Speaker 1: I guess we'll find out if he listens to the

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Speaker 1: if he responds to this.

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Speaker 2: Oh boy one.

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Speaker 3: In case you're listening, Hello, Daniel's brother. It sounds like

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Speaker 3: we should have you on a podcast and break it

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Speaker 3: down Oprah style.

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Speaker 1: He's been on the podcast once before when we talked

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Speaker 1: about artificial intelligence because he's a machine learning professor.

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Speaker 3: Oh I thought you were going to say he's a

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Speaker 3: machine that too. But anyways, welcome to our podcast. Daniel

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Speaker 3: and Jorge explain the Universe a production of our Heart

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Speaker 3: Radio in.

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Speaker 1: Which we try not to eclipse your knowledge of the universe.

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Speaker 1: We try to shine a light on it. We think

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Speaker 1: everybody should be cozy with the physics of the universe,

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Speaker 1: snuggling up to a deep understanding of what's going on

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Speaker 1: out there, how it all works, how it started, and

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Speaker 1: what story it tells us about where we live and

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Speaker 1: where we will live in the future.

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Speaker 2: That's right.

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Speaker 3: We tried to be your big brother in terms of

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Speaker 3: telling you how the universe works and what we've learned

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Speaker 3: from our mistakes and our discoveries so that you can

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Speaker 3: navigate this fantastic universe with a little bit more ease

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Speaker 3: and a little bit more confidence.

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Speaker 1: I'm not sure Big Brother has the meditations we're looking for.

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Speaker 1: You know, it's a little bit overwhelminging, isn't it.

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Speaker 3: M not necessarily Isn't there like a Big Brother program

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Speaker 3: where you mentor kids.

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Speaker 2: That's a positive thing too.

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Speaker 1: Yeah, there you go. We're not telling you what to

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Speaker 1: think of what not to think. We're just teaching you

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Speaker 1: about the universe.

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Speaker 2: That's right.

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Speaker 3: And there is a lot to know about the universe

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Speaker 3: and to discover and to find out because it is

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Speaker 3: pretty interesting, pretty complex, pretty vast, and also microscopic in

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Speaker 3: the way that it reveals its secrets.

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Speaker 1: And one surefire way to figure out how the universe

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Speaker 1: works is to ask basic questions about it. To look

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Speaker 1: up at the night sky and ask why does this

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Speaker 1: do this? And why does this not do that? How

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Speaker 1: can we see this happening and not some other thing happening.

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Speaker 1: What are the rules of the universe that allow us

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Speaker 1: to have huge planets like Jupiter but not other situations

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Speaker 1: like planets shaped like a pretzel.

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Speaker 3: Yeah, because I guess you can look around and wonder like,

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Speaker 3: are we a result of the rules of the universe

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Speaker 3: or are we like an exception to the rules of

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Speaker 3: the universe.

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Speaker 1: Well, we definitely a results of the rules of the universe,

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Speaker 1: if you believe the universe has rules and it follows them.

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Speaker 1: But there might be weird outcomes and there might be

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Speaker 1: standard outcomes like it. It could be that our solar system

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Speaker 1: is very unusual as an example of things in the galaxy,

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Speaker 1: or it could be that were totally vanilla.

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Speaker 3: Yeah, because as humans here on planet Earth, we only

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Speaker 3: really have one view of one planet that we can

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Speaker 3: study up close so far, and so it makes you

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Speaker 3: wonder if other planets are the same, or if humans

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Speaker 3: could have lived in other planets, could things have been

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Speaker 3: different in our history?

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Speaker 1: That's true, and there are other planets nearby that we

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Speaker 1: can study, though not quite as up close, to try

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Speaker 1: to get more insight into what a planet can be, like,

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Speaker 1: what are the various possibilities how planets can turn out?

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Speaker 3: And do they get along as siblings? Or have any

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Speaker 3: siblings been kicked out of the Solar System and are

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Speaker 3: living in intents by the asteroid build That's right.

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Speaker 1: We talked recently about those really fun theories that there

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Speaker 1: was once an ice giant in the outer Solar System

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Speaker 1: that was ejected during a period of chaos.

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Speaker 3: WHOA, so you think it just couldn't get along with

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Speaker 3: the other planets.

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Speaker 1: I'm wondering who the parent is this analogy? Like, is

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Speaker 1: it really the Sun's fault that it didn't work out?

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Speaker 4: Yeah?

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Speaker 3: And how responsible is it to kick your children outside

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Speaker 3: and live outside?

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Speaker 2: Yeah? Yeah, somebody should call it you universal child services.

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Speaker 1: But one thing we do notice about our Solar System

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Speaker 1: is that the planets all seem to have their own orbits.

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Speaker 1: Jupiter's got an orbit, or Earth has an orbit, Mars

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Speaker 1: has an orbit. It's sort of like everybody's got their

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Speaker 1: own room.

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Speaker 2: They all have their own lane.

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Speaker 1: You mean, yeah, exactly.

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Speaker 3: Like there's no other Earth on the other side of

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Speaker 3: our orbit, right, or didn't scientists think for a while,

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Speaker 3: or maybe there was?

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Speaker 1: It sounds like a pretty cool science fiction story, right,

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Speaker 1: a second Earth on the other side of the Sun.

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Speaker 2: Planet X. Wasn't it called Planet X?

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Speaker 1: I think planet X is an idea for a tenth

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Speaker 1: or now ninth planet that might be out there tugging

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Speaker 1: on distant planets, but wouldn't necessarily share an orbit with ours.

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Speaker 3: But it's technically is it possible that there's like another

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Speaker 3: Earth on the other side of the Sun? Weich just

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Speaker 3: have never seen it because it's on the other side

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Speaker 3: of the Sun.

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Speaker 1: We wouldn't be able to see it directly from Earth.

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Speaker 1: But of course we've had probes go all over the

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Speaker 1: Solar System. We would have seen it, and we would

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Speaker 1: have noticed its gravitational effects on Mars and Venus and

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Speaker 1: other stuff in the Solar System.

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Speaker 3: So I guess each planet does have its own orbit,

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Speaker 3: its own lane.

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Speaker 1: In our Solar System, each planet mostly does have its

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Speaker 1: own lane. But of course the question is why is

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Speaker 1: that and is that typical? So today on the podcast,

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Speaker 1: we'll be tackling the question why don't planet share an orbit?

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Speaker 1: Is it because they couldn't get along? Yeah?

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Speaker 2: And are we the little the younger sibling or are

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Speaker 2: we the more accomplished sibling.

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Speaker 1: I think the younger sibling is often motivated to eclipse

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Speaker 1: the older siblings.

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Speaker 2: Boy, it sounds like a lot to impact there in

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Speaker 2: your family.

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Speaker 1: I'm nothing but proud of my younger brother.

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Speaker 3: Let's stick to physics maybe, but yeah, it's an interesting question.

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Speaker 3: I guess the implied fact is that no planets in

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Speaker 3: our Solar system share an orbit, meaning they're not going

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Speaker 3: around the Sun at the same distance.

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Speaker 1: Yeah, although you could quibble about that in the case

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Speaker 1: of Jupiter. There is some stuff in Jupiter's orbit, not

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Speaker 1: another planet, but it does share its orbit with some

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Speaker 1: other chunks.

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Speaker 3: And I guess the other implied fact is that all

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Speaker 3: the orbits don't overlap. I guess right, because most of

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Speaker 3: the orbits are pretty much circular, right, They're not like

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Speaker 3: ellipses that kind of overlap with each other.

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Speaker 1: You mean, like if they intersect, Yeah.

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Speaker 3: Like they intersect, or if you look at them from

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Speaker 3: the top they're maybe like the two ellipsoids are overlapped.

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Speaker 1: Yeah, I think two ellipsoids that overlap and have different

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Speaker 1: periods would eventually collide. So I don't think you could

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Speaker 1: have that situation for very long.

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Speaker 3: But it's true that most of the orbits are pretty

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Speaker 3: much circular, right.

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Speaker 1: They're all a little bit eccentric. None of them are

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Speaker 1: exactly circular, kind of.

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Speaker 3: Like you and your brothers. They're all a little eccentric

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Speaker 3: as well. I think a little is kind of generous there.

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Speaker 3: We're all quite eccentric. Actually called professors or something.

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Speaker 1: Exactly how does that happen? But in the case of

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Speaker 1: the Solar system, none of the orbits are perfectly circular.

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Speaker 1: They're all at least a little bit eccentric. But yeah,

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Speaker 1: none of them are overlapping. They basically all have their

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Speaker 1: own lanes.

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Speaker 3: So the question is why don't two planets have the

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Speaker 3: same orbit? So, as usually'll be ever wondering how many

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Speaker 3: people out there had thought about this question.

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Speaker 1: Thanks very much to our group of volunteers. We'd love

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Speaker 1: if you joined them. Right to me two questions at

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Speaker 1: Daniel and Jorge dot com, and I'll send the questions

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Speaker 1: on over.

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Speaker 3: So think about it for a second. Why do you

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Speaker 3: think no two planets share an orbit. Here's what people

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Speaker 3: had to say.

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Speaker 5: I think planets don't share orbits because the center of

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Speaker 5: gravity would have to be absolutely stationary, or it'd oscillate

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Speaker 5: and shake itself out of sync.

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Speaker 2: But I think they actually do. It's just very unlikely

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Speaker 2: because it'd be a major coincidence.

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Speaker 4: So I'm under the impression that planet's by definition or

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Speaker 4: celestial objects orbiting stars that have cleared their orbital path

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Speaker 4: of competing debris like asteroids, and that as a planet forms,

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Speaker 4: it's gravity gets stronger and it sucks up other objects

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Speaker 4: in that orbital path. And that's one of the reasons

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Speaker 4: that objects like series are not considered true planets because

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Speaker 4: they share their orbit with a number of other large

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Speaker 4: asteroids and other computing debris.

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Speaker 6: Planets don't share orbits because of the way closters get together.

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Speaker 6: If there is a clumpup matter very close to another

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Speaker 6: glombal matter, they will make a planet, and the things

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Speaker 6: that are fought up are they will make another planet.

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Speaker 3: All right, some interesting answers. Some people think it's maybe

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Speaker 3: unlikely because there would be a big coincidence.

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Speaker 1: Or that gravity just doesn't work that way, that it

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Speaker 1: can't pull things together into two planets.

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Speaker 3: Oh interesting, but I guess you know, thinking about it,

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Speaker 3: like the asteroid built has a whole bunch of mini

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Speaker 3: planets and they're all kind of in the same orbit.

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Speaker 1: Mm hmm, yeah, absolutely, I.

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Speaker 3: Guess we'll dig into that. So first of all, Daniel,

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Speaker 3: let's maybe start with the basics. What is a planet

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Speaker 3: or what do you define as a planet?

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Speaker 1: So a planet famously has a fairly legalistic definition of

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Speaker 1: what it is. And remember this is just a rooms

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Speaker 1: giving names to things, Like there's stuff out there in

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Speaker 1: the universe. The rocks don't care whether you call them

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Speaker 1: a rock or an asteroid or a planet or a planetismal,

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Speaker 1: They're still out there and doing the physics. This is

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Speaker 1: just humans applying like our framework of categorization to the stuff,

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Speaker 1: and different humans on a different planet, or aliens whatever

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Speaker 1: it might come up with a totally different categorization. It's

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Speaker 1: mostly historical. It doesn't really reflect deep underlying physics. But

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Speaker 1: it's language and we should all agree what the meanings

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Speaker 1: of words are. And so in the case of a planet,

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Speaker 1: there are three requirements. One that it's mostly spherical, This

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Speaker 1: is basically isn't big enough, because anything that's big enough

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Speaker 1: is going to be mostly as fear due to gravity.

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Speaker 1: Requirement Number two is that it orbits the Sun and

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Speaker 1: not some other object like a planet, otherwise the Moon

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Speaker 1: would be a candidate for a planet. And then the

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Speaker 1: last one is that it's cleared its path of planetismals

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Speaker 1: and other big objects, basically that of all the stuff

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Speaker 1: in its lane, it's gathered up all the bits into

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Speaker 1: one object.

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Speaker 3: Well, it sounds like by definition then a planet cannot

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Speaker 3: share an orbit, because a planet in your definition, is

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Speaker 3: something that is by itself in an orbit exactly.

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Speaker 1: So technically speaking, like the legal answer is no, because

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Speaker 1: then it wouldn't be a planet. But really we're asking, like,

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Speaker 1: could you have two Jupiters on opposite sides of the

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Speaker 1: Sun orbiting in the same orbit. That would be really fascinating.

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Speaker 1: Now astronomers from this committee would say, well, technically those

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Speaker 1: aren't planets, and we say like, well, we don't really care.

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Speaker 1: It's fascinating that they're doing this thing, whether or not

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Speaker 1: you call them planets.

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Speaker 3: I mean, if there was another Earth orbiting in our orbit,

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Speaker 3: just on the other side of the Sun, we wouldn't

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Speaker 3: be like, that's not a planet. We would still call

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Speaker 3: it a planet, and you'd just be forced to change

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Speaker 3: the definition of a planet.

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Speaker 1: Yeah. Maybe, Or we'd have t shirts saying like Earth

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Speaker 1: isn't a planet, or Earth is a planet, or I'm

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Speaker 1: on Team Earth or whatever. It'd be a whole ridiculous

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Speaker 1: battle really just over names. You know, where do you

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Speaker 1: draw the dotted line?

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Speaker 3: But I guess maybe the question is like, why is

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Speaker 3: that part of the definition? Why is it important for

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Speaker 3: astronomers it a planet? It quote unquote has its own orbit.

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Speaker 1: It's a good question, and I don't think the answer

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Speaker 1: is just scientific. I think it's historical. You know, we

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Speaker 1: try to sometimes reverse engineer these definitions to reflect the

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Speaker 1: decisions we've been making historically. We've been calling these things planets,

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Speaker 1: and we sort of want to have a definition that

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Speaker 1: aligns with the decisions we've already made, even if they

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Speaker 1: aren't the decisions we would have made if we knew

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Speaker 1: better at the time. You know, early on, when we

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Speaker 1: started talking about planets, we didn't understand everything that was

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Speaker 1: out there in the Solar System, all the smaller rocks

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Speaker 1: that were invisible to us. We didn't realize that there

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Speaker 1: was like a full spectrum from tiny rocks to planetisimals,

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Speaker 1: to dwarf planets to real planets.

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Speaker 3: But I guess maybe the idea that this is part

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Speaker 3: of the definition maybe tells me that there are things

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Speaker 3: out there that are spherical that orbit the Sun but

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Speaker 3: that don't have cleared its path of planetesimals, that are

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Speaker 3: maybe as big as some of the things we do

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Speaker 3: call planets.

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Speaker 2: Is that true?

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Speaker 1: Well, basically that's Pluto, right. Pluto got rejected as a

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Speaker 1: planet because it was judged to have not sufficiently cleared

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Speaker 1: the neighborhood around its orbit of other stuff. Basically, if

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Speaker 1: you look in Pluto's orbit, you find other pretty big

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Speaker 1: rocks that are roughly the size of Pluto. Pluto is

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Speaker 1: just one of an example of lots of we call

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Speaker 1: them dwarf planets that far out in the Solar System.

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Speaker 1: They have not gathered together sufficiently to say there's one

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Speaker 1: really dominant object and nothing else out there.

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Speaker 2: Wait wait, wait, wait wait, this was the rule that.

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Speaker 3: They kicked Pluto out because of you mean it's not

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Speaker 3: because of its size. I always thought it was because

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Speaker 3: of its size.

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Speaker 1: It's sort of indirectly because of its size. I mean,

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Speaker 1: if everything else out there in Pluto's orbit was just

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Speaker 1: dust and tiny grains, then they would have said, okay,

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Speaker 1: it's a planet. But because there are chunks of rock

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Speaker 1: out there that are sort of too big to ignore,

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Speaker 1: then you say Pluto hasn't really cleared its orbit. I mean, really,

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Speaker 1: technically speaking, nothing has cleared its orbit, because you know

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Speaker 1: there's dust and all sorts of other rocks in Earth's

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Speaker 1: orbit certainly, right, It's not like it's perfectly empty space

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Speaker 1: in Earth's orbit, So you can ask like, well, what

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Speaker 1: does it mean to clear its orbit? Even that definition

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Speaker 1: gets a little bit fuzzy, but that's the reason why

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Speaker 1: Pluto was demoted.

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Speaker 2: WHOA, I'm a little bit outraged.

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Speaker 3: I feel like this is such a weird technicality to

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Speaker 3: have kick Pluto for.

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Speaker 1: Well, this is the problem with creating categories, right, You're

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Speaker 1: always going to find something on the edge of the category,

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Speaker 1: and then you're going to have to try to crisply

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Speaker 1: define the category, and then you discover the category is

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Speaker 1: just artificial. You're just really drawing dotted lines between a

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Speaker 1: smooth spectrum of stuff. Like I remember when we talked

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Speaker 1: about space centaurs, the things that are so kind of

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Speaker 1: comets and kind of asteroids, And what you discover is

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Speaker 1: really the two things are part of a larger community.

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Speaker 1: And you've drawn a dotted line between comets and asteroids,

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Speaker 1: and it doesn't really make sense to distinguish between them.

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Speaker 1: This is just a problem of humans creating categories that

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Speaker 1: don't really work.

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Speaker 3: But there was sort of like a voter, there was

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Speaker 3: a lot of discussion about Pluto. So what is it

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Speaker 3: about not having anything in its path that is so

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Speaker 3: important to scientists to kick go, you know, change science

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Speaker 3: books basically for everybody. You know, why is that important

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Speaker 3: whether or not it has little chunks of rocks in

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Speaker 3: its path or not.

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Speaker 1: I think it's just sociological, Like we look at Earth

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Speaker 1: and Jupiter and Mars and Venus and we say this

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Speaker 1: is one kind of thing, and Pluto is sort of

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Speaker 1: a different kind of thing because it's different in this way.

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Speaker 1: Is just one example of many big chunks of rock

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Speaker 1: out there in the Pluto orbit. So I think there

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Speaker 1: is a distinction to be made between these two different

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Speaker 1: categories of objects. Then again, it's sort of fuzzy.

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Speaker 3: Meaning like the fact that it has chunks in its

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Speaker 3: path is maybe the only thing that sits it apart

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Speaker 3: from the others, like none of the other things that

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Speaker 3: we call planets have things in its path, and so

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Speaker 3: they're using this as an excuse to kick Pluto out exactly.

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Speaker 1: And when we talk about the history of the formation

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Speaker 1: of the Solar System, you see that it's sort of

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Speaker 1: like one step, you know, the Solar System. You have

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Speaker 1: the planetary disk, and it gathers into rocks and those

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Speaker 1: become planetesimals, and then in some cases they form big

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Speaker 1: planets and other cases they just stay a big spread

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Speaker 1: of planet isimals, they don't really form planets. So in

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Speaker 1: that sense, planets really are sort of like the next

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Speaker 1: step in the formation of an object in the Solar System,

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Speaker 1: and you've got to respect that or reflect it, or

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Speaker 1: at least, you know, describe it.

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Speaker 6: You know.

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Speaker 3: I guess it would make sense if there were a

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Speaker 3: lot of Pluto like planets that look like Pluto or

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Speaker 3: the size of Pluto, but didn't clear its path, and

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Speaker 3: then maybe I could see like, Okay, if you let

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Speaker 3: Pluto in, you have to let all these other things in.

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Speaker 3: But is that the case, or is Pluto just like

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Speaker 3: a loan border case.

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Speaker 1: Well, Pluto is maybe the thing closest to the edge.

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Speaker 1: But there are a lot of things out there, you know,

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Speaker 1: there aren't a lot of these dwarf planets that you

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Speaker 1: might call planets. You know, Series, for example, is a

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Speaker 1: dwarf planet, but it's part of the asteroid belt, and

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Speaker 1: there's lots of other stuff in the asteroid belt. So

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Speaker 1: you can't say that Series really is a planet because

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Speaker 1: it didn't gather together all the other bits. So I

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Speaker 1: think that is true that once you open the door

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Speaker 1: to Pluto, you have to let in lots of other folks.

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Speaker 1: I don't know why that's the problem. Like, let's have

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Speaker 1: a solar system with hundreds of planets. That sounds awesome

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Speaker 1: to be big party.

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Speaker 2: Yeah, more savings to fight with.

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Speaker 1: But there is something of a distinction here between objects

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Speaker 1: that are basically alone in their orbit and objects that

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Speaker 1: are not. And I do think it's really interesting to wonder, like,

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Speaker 1: could you have two planet like objects orbiting the Sun

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Speaker 1: in the same orbit. Why don't we see that in

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Speaker 1: our solar system? Is that something you might see in

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Speaker 1: other solar systems, et cetera.

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Speaker 3: I see, you want to sort of pivot to the

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Speaker 3: question of like what would happen if two planets did

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Speaker 3: share an orbit, or two large objects like the Earth

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Speaker 3: share it an orbit.

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Speaker 1: Could that situation be stable? Why don't we see it?

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Speaker 1: Could that form at all? I think those are really

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Speaker 1: interesting sort of physics questions instead of like category legalistic questions.

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Speaker 3: That sounds like something siblings would argue about for no

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Speaker 3: good reason. All right, well let's dig into these interesting questions.

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Speaker 3: But first let's take a quick break. All right, we're

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Speaker 3: asking the question here today why don't planets share an orbit?

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Speaker 3: And we just went through a defined print to find

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Speaker 3: out that astronomers call a planet something that doesn't share

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Speaker 3: an orbit, So technically planets cannot share an orbit. But

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Speaker 3: now we're going to pivot a little bit and ask

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Speaker 3: the question, well, what would happen if something like the

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Speaker 3: Earth share it an orbit with another big thing like

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Speaker 3: the Earth. Well, first of all, you would get kicked

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Speaker 3: out of the planet category, right.

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Speaker 1: Yeah, that's right. If you built an earth sized death

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Speaker 1: star and put it in orbit on the other side

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Speaker 1: of the Sun, then Earth would no longer be a planet.

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Speaker 3: Would you say, maybe the Moon is still something that

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Speaker 3: we haven't cleared.

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Speaker 1: Well, but the Moon is orbiting the Earth, right, so

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Speaker 1: mm hmmm, Oh, I see what you mean. Does the

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Speaker 1: Moon disqualify the Earth because we haven't absorbed it into

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Speaker 1: the Earth? Oh yeah, these are complicated legal questions.

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Speaker 3: That sounds like we need a lawyer. Is the brother

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Speaker 3: a lawyer, also an accomplished lawyer.

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Speaker 1: Probably he's arguing in front of the Astronomy Supreme Court

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Speaker 1: right now.

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Speaker 2: Yeah. No, he just broken a machine to do it

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Speaker 2: for it.

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Speaker 3: But yeah, so I guess we're asking more of a

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Speaker 3: physics question, not a technical definition question like could you

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Speaker 3: have two giant Earth or to jupiters kind of circling

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Speaker 3: each other maybe opposite sides of the Sun or maybe not.

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Speaker 2: I don't know. That's kind of the question now, right, Yeah, I.

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Speaker 1: Think that's the interesting physics question. You know, is that possible?

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Speaker 1: Is there some law physics that prevents that from happening,

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Speaker 1: either to stop it from forming or to break it

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Speaker 1: up if it did somehow randomly land that way?

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Speaker 3: Because I guess the question is have we seen that

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Speaker 3: We haven't seen that in our Solar system or have

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Speaker 3: we maybe like Pluto has it and anti Pluto out there.

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Speaker 1: So we don't have examples of Earth sized objects with

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Speaker 1: other Earth sized objects in their orbits. But we do

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Speaker 1: have in our Solar system some sort of edge cases,

444
00:19:46,720 --> 00:19:50,320
Speaker 1: Like Jupiter has a whole collection of asteroids that are

445
00:19:50,359 --> 00:19:52,879
Speaker 1: not in the asteroid belt per se, the one you

446
00:19:52,920 --> 00:19:55,679
Speaker 1: think about between Mars and Jupiter, but are actually in

447
00:19:55,880 --> 00:19:58,800
Speaker 1: its orbit. There's two different groups of asteroids that are

448
00:19:58,840 --> 00:20:00,720
Speaker 1: orbiting with jupil Wait.

449
00:20:00,560 --> 00:20:03,040
Speaker 3: Wait, wait, Like on the opposite side of Jupiter from

450
00:20:03,040 --> 00:20:05,160
Speaker 3: the Sun, there's a whole bunch of debris.

451
00:20:05,200 --> 00:20:07,560
Speaker 1: So not on the opposite side of Jupiter. It's sort

452
00:20:07,560 --> 00:20:10,080
Speaker 1: of thirty degrees trailing and thirty degrees ahead of it.

453
00:20:10,520 --> 00:20:13,919
Speaker 1: Because there are several stable points around Jupiter where you

454
00:20:13,920 --> 00:20:16,480
Speaker 1: can balance the gravity of Jupiter and the gravity of

455
00:20:16,520 --> 00:20:18,560
Speaker 1: the Sun, so they cancel out. These are called the

456
00:20:18,640 --> 00:20:22,520
Speaker 1: lagrange points, And in the fourth and fifth Lagrange points

457
00:20:22,760 --> 00:20:25,440
Speaker 1: in front of Jupiter and behind Jupiter in its orbit,

458
00:20:25,480 --> 00:20:27,720
Speaker 1: there's a whole collection of asteroids that are sort of

459
00:20:27,720 --> 00:20:28,440
Speaker 1: hanging out there.

460
00:20:28,560 --> 00:20:30,840
Speaker 2: Whoa Well, does that mean Jupiter is not a planet?

461
00:20:31,119 --> 00:20:35,360
Speaker 1: I know exactly right, Like, has Jupiter really cleared its orbit? Well,

462
00:20:35,400 --> 00:20:38,320
Speaker 1: it's so much bigger than these rocks that I guess

463
00:20:38,359 --> 00:20:41,000
Speaker 1: you can say so. But like if I were Pluto's lawyers,

464
00:20:41,040 --> 00:20:43,480
Speaker 1: I would have raised that example, right right.

465
00:20:43,600 --> 00:20:47,280
Speaker 3: Why didn't anybody raise that example? Was nobody advocating for

466
00:20:47,320 --> 00:20:52,200
Speaker 3: Pluto or four science books in general and not confusing

467
00:20:52,200 --> 00:20:53,400
Speaker 3: the entire human population.

468
00:20:55,400 --> 00:20:57,400
Speaker 1: I'm not going to make the mistake of trying to

469
00:20:57,440 --> 00:20:59,919
Speaker 1: defend any of these definitions, because to me, they're all

470
00:21:00,280 --> 00:21:03,360
Speaker 1: just arbitrary, and they all break down under some scenario.

471
00:21:03,760 --> 00:21:06,240
Speaker 1: And this is an example, you know, and Earth even

472
00:21:06,280 --> 00:21:08,800
Speaker 1: has one of these. Earth has an object like this

473
00:21:09,000 --> 00:21:11,199
Speaker 1: that's in its orbit. That orbit's in one of its

474
00:21:11,280 --> 00:21:12,960
Speaker 1: lagrange points. It's a pretty big rock.

475
00:21:13,200 --> 00:21:17,000
Speaker 3: Wait, what really? How big is it? It's not that big.

476
00:21:17,119 --> 00:21:20,520
Speaker 3: It's like five kilometers in diameter. We've only known about

477
00:21:20,560 --> 00:21:23,280
Speaker 3: it since like nineteen eighty six when it was first spotted.

478
00:21:23,400 --> 00:21:26,000
Speaker 3: It's got this terrible name I won't even try to pronounce,

479
00:21:26,080 --> 00:21:30,000
Speaker 3: but it's spelled c r ui, thh and E. Maybe

480
00:21:30,000 --> 00:21:34,640
Speaker 3: you can pronounce it, maybe, yeah, but not on air apparently.

481
00:21:35,200 --> 00:21:37,960
Speaker 1: Anyway, It's the sort of feature of gravity. You know,

482
00:21:38,000 --> 00:21:40,320
Speaker 1: there are places you can be where you can be

483
00:21:40,359 --> 00:21:42,879
Speaker 1: in a stable orbit, like the James Web Space Telescope

484
00:21:42,960 --> 00:21:45,919
Speaker 1: is in one of these lagrange points relative to the

485
00:21:45,960 --> 00:21:46,880
Speaker 1: Earth and the Sun.

486
00:21:47,080 --> 00:21:50,200
Speaker 3: Well, I think what you mean by stable orbit points

487
00:21:50,359 --> 00:21:54,000
Speaker 3: meaning that it has the same location relative to the

488
00:21:54,160 --> 00:21:56,880
Speaker 3: Earth and it goes around the Sun at the same rate,

489
00:21:57,080 --> 00:21:58,520
Speaker 3: like it takes the same amount of time to go

490
00:21:58,560 --> 00:22:00,600
Speaker 3: around the Sun. That's what you mean by like being

491
00:22:00,640 --> 00:22:01,600
Speaker 3: in a stable position.

492
00:22:01,720 --> 00:22:03,600
Speaker 1: Well, there's two different things there. One is being in

493
00:22:03,640 --> 00:22:06,520
Speaker 1: the same orbit, and that means following the same path,

494
00:22:06,600 --> 00:22:08,520
Speaker 1: taking the same amount of time to go around the Sun.

495
00:22:08,720 --> 00:22:12,119
Speaker 1: The second thing is whether you're stable, and stability beings

496
00:22:12,160 --> 00:22:14,360
Speaker 1: like if you get a little push, do you return

497
00:22:14,520 --> 00:22:17,040
Speaker 1: back to the path you are on or does that

498
00:22:17,080 --> 00:22:19,840
Speaker 1: cause like a cascade where it creates a bigger push

499
00:22:19,840 --> 00:22:21,639
Speaker 1: and then a bigger push, and then a bigger push

500
00:22:21,880 --> 00:22:23,840
Speaker 1: and then you fall away, sort of the way like

501
00:22:23,920 --> 00:22:27,000
Speaker 1: a pencil balanced on its tip is unstable. The tin

502
00:22:27,160 --> 00:22:29,480
Speaker 1: is little push and it will fall over. But like

503
00:22:29,520 --> 00:22:31,400
Speaker 1: a ball in the bottom of a glass is stable.

504
00:22:31,520 --> 00:22:34,199
Speaker 1: You give it a little push, gravity restores it back to

505
00:22:34,240 --> 00:22:37,359
Speaker 1: where it was. So some configurations are stable, meaning that

506
00:22:37,400 --> 00:22:40,520
Speaker 1: gravity will push them back to that configuration if they

507
00:22:40,520 --> 00:22:42,440
Speaker 1: get pushed by a little rock or hit by the

508
00:22:42,480 --> 00:22:44,880
Speaker 1: solar wind or whatever. And if you have two objects

509
00:22:44,960 --> 00:22:47,120
Speaker 1: like the Sun and the Earth, there are five points

510
00:22:47,160 --> 00:22:50,000
Speaker 1: are called the garage points that are stable. Three of

511
00:22:50,040 --> 00:22:52,480
Speaker 1: them are in your orbit, and two of them are.

512
00:22:52,320 --> 00:22:54,600
Speaker 3: Not right, meaning three of them are in the same

513
00:22:54,640 --> 00:22:57,479
Speaker 3: circle that the Earth traces around the Sun, and two

514
00:22:57,560 --> 00:22:59,639
Speaker 3: of them are like one of them a little bit

515
00:22:59,640 --> 00:23:02,000
Speaker 3: further the circle and the other one closer to the Sun.

516
00:23:02,040 --> 00:23:04,119
Speaker 3: And if you're at those positions going at the right speed,

517
00:23:04,160 --> 00:23:07,080
Speaker 3: then you're going to trace a circle kind of along with.

518
00:23:07,119 --> 00:23:09,800
Speaker 1: The Earth exactly. The simplest one to understand is that

519
00:23:09,840 --> 00:23:12,600
Speaker 1: there's a point between the Earth and the Sun where

520
00:23:12,640 --> 00:23:14,720
Speaker 1: the gravity cancels up because the Sun is pulling in

521
00:23:14,760 --> 00:23:16,960
Speaker 1: one way and the Earth is pulling another way. And

522
00:23:17,040 --> 00:23:19,560
Speaker 1: if you're just the right point, it's not halfway between

523
00:23:19,560 --> 00:23:21,280
Speaker 1: the Earth and the Sun, because the Sun is obviously

524
00:23:21,320 --> 00:23:23,800
Speaker 1: more massive and has more gravity, But there is a

525
00:23:23,840 --> 00:23:26,520
Speaker 1: point there where the Earth and the Sun gravity balances out,

526
00:23:26,560 --> 00:23:29,760
Speaker 1: and if you're right there, there's effectively no gravity and

527
00:23:29,800 --> 00:23:32,200
Speaker 1: you could just move with the same period though not

528
00:23:32,280 --> 00:23:34,920
Speaker 1: the same velocity as the Earth and stay there.

529
00:23:34,760 --> 00:23:37,240
Speaker 3: Meaning like you'll go around the Sun in exactly a year,

530
00:23:37,520 --> 00:23:38,120
Speaker 3: just like the Earth.

531
00:23:38,240 --> 00:23:39,200
Speaker 1: Mm hmm, exactly.

532
00:23:39,320 --> 00:23:41,120
Speaker 3: That's what it means to kind of share an orbit

533
00:23:41,200 --> 00:23:43,119
Speaker 3: in that case, you would have a different radius, so

534
00:23:43,200 --> 00:23:45,000
Speaker 3: you'd have the same period, but it wouldn't really be

535
00:23:45,000 --> 00:23:47,280
Speaker 3: the same orbit. But there are three of these points

536
00:23:47,480 --> 00:23:49,720
Speaker 3: that are actually in the same orbit, meaning you're following

537
00:23:49,800 --> 00:23:51,920
Speaker 3: the same path. One of them is on the other

538
00:23:52,040 --> 00:23:53,920
Speaker 3: side of the Sun from the Earth, as you said,

539
00:23:53,920 --> 00:23:56,840
Speaker 3: And that's very intuitive, right, and because you're like exactly

540
00:23:56,880 --> 00:23:58,919
Speaker 3: balancing the Earth, and so you could just be like

541
00:23:59,040 --> 00:24:01,920
Speaker 3: constantly a hundred eighty degrees out of phase with the Earth.

542
00:24:02,320 --> 00:24:05,280
Speaker 3: And then there are two points thirty degrees behind and

543
00:24:05,359 --> 00:24:08,199
Speaker 3: thirty degrees ahead of the Earth that also have this

544
00:24:08,240 --> 00:24:12,560
Speaker 3: special gravitational balance where the Sun and the Earth effectively

545
00:24:12,600 --> 00:24:14,040
Speaker 3: neutralize each other's gravity.

546
00:24:14,240 --> 00:24:16,080
Speaker 2: And does it depend on how big you are or

547
00:24:16,440 --> 00:24:17,400
Speaker 2: how heavy you are.

548
00:24:17,280 --> 00:24:19,240
Speaker 1: So the location of some of these points do depend

549
00:24:19,359 --> 00:24:22,159
Speaker 1: on the mass ratios, but the other ones are just geometric.

550
00:24:22,680 --> 00:24:26,240
Speaker 1: So Jupiter has them, Earth has them. All the planets

551
00:24:26,320 --> 00:24:29,320
Speaker 1: have these lagrange points, and that's why, for example, Jupiter

552
00:24:29,400 --> 00:24:33,040
Speaker 1: has this collection of asteroids behind it and ahead of it,

553
00:24:33,080 --> 00:24:36,320
Speaker 1: because they're hanging out at one of these lagrange points.

554
00:24:36,320 --> 00:24:38,160
Speaker 3: Okay, so I think what we're trying to say here

555
00:24:38,280 --> 00:24:41,120
Speaker 3: is that each planet has an orbit and each orbit

556
00:24:41,200 --> 00:24:43,480
Speaker 3: sort of has these spots where you could maybe put

557
00:24:43,480 --> 00:24:46,080
Speaker 3: in another planet and it would still be stable, and

558
00:24:46,119 --> 00:24:48,480
Speaker 3: both of them keep going around the Sun, like it's possible.

559
00:24:48,560 --> 00:24:51,720
Speaker 1: It's possible. One tiny little wrinkle there is that some

560
00:24:51,760 --> 00:24:55,080
Speaker 1: of these logrange points are stable, some of them are unstable.

561
00:24:55,280 --> 00:24:57,520
Speaker 1: There are all locations where the gravity balance is out

562
00:24:57,560 --> 00:24:59,359
Speaker 1: and if you're exactly at the right spot, you can

563
00:24:59,359 --> 00:25:01,800
Speaker 1: stay there for ever. But some of them are unstable,

564
00:25:01,840 --> 00:25:04,159
Speaker 1: meaning if you deviate a tiny little bit, it's like

565
00:25:04,200 --> 00:25:06,399
Speaker 1: a pencil leaning over on the table. It's going to

566
00:25:06,440 --> 00:25:08,399
Speaker 1: fall over and you're not going to return. Where some

567
00:25:08,440 --> 00:25:10,879
Speaker 1: of them are stable, meaning that if you deviate a

568
00:25:10,880 --> 00:25:12,960
Speaker 1: little bit, you'll come back. So the fourth and fifth

569
00:25:13,040 --> 00:25:15,800
Speaker 1: le Graunge points, so one ahead and behind you in

570
00:25:15,840 --> 00:25:19,640
Speaker 1: the orbit, are actually stable locations. So yeah, and principle,

571
00:25:19,680 --> 00:25:21,680
Speaker 1: you could have another Earth that's not on the other

572
00:25:21,800 --> 00:25:24,680
Speaker 1: side of the Sun, but just like thirty degrees behind

573
00:25:24,760 --> 00:25:26,800
Speaker 1: us in our orbit, and it could be there and

574
00:25:26,880 --> 00:25:28,399
Speaker 1: be stable gravitationally.

575
00:25:28,560 --> 00:25:30,720
Speaker 3: But didn't you say it sort of depends on the mass,

576
00:25:30,840 --> 00:25:32,800
Speaker 3: like and you can imagine if I put a James

577
00:25:32,800 --> 00:25:35,760
Speaker 3: Web telescope, it'll be stable there, or maybe a small

578
00:25:35,800 --> 00:25:38,720
Speaker 3: asteroid or five kilometer rock. But if I put a

579
00:25:38,720 --> 00:25:42,200
Speaker 3: whole Earth, wouldn't it just destabilize the whole thing? Or

580
00:25:42,240 --> 00:25:45,359
Speaker 3: wouldn't it be totally a different point?

581
00:25:45,400 --> 00:25:47,600
Speaker 1: If you put another Earth there, it would be stable,

582
00:25:47,920 --> 00:25:50,760
Speaker 1: Like the situation is symmetric and they could both survive there.

583
00:25:51,400 --> 00:25:54,280
Speaker 1: There are mass limitations, like if you put a star

584
00:25:54,480 --> 00:25:57,120
Speaker 1: there that's much more massive than the Earth I think

585
00:25:57,200 --> 00:25:58,960
Speaker 1: is like a limit of like twenty five times the

586
00:25:58,960 --> 00:26:01,080
Speaker 1: mass of the Earth, then make some assumptions it doesn't

587
00:26:01,080 --> 00:26:03,560
Speaker 1: work anymore. But you could put a pretty massive planet

588
00:26:03,600 --> 00:26:04,920
Speaker 1: there and it would be stable.

589
00:26:05,119 --> 00:26:07,960
Speaker 3: Interesting. But then now the question is why isn't there

590
00:26:08,000 --> 00:26:09,720
Speaker 3: something there? Because I'm sure at the beginning of the

591
00:26:09,720 --> 00:26:12,720
Speaker 3: Solar system they're asteroids everywhere, there are rocks everywhere. Why

592
00:26:12,760 --> 00:26:15,680
Speaker 3: didn't those two points start to gather things? And why

593
00:26:15,680 --> 00:26:17,400
Speaker 3: don't we have a little twin Earth.

594
00:26:17,560 --> 00:26:19,280
Speaker 1: The answer to that is that we don't really know.

595
00:26:19,600 --> 00:26:21,639
Speaker 1: I mean, we think that in the formation of a

596
00:26:21,680 --> 00:26:24,879
Speaker 1: Solar system, it's possible for it to happen. Remember the

597
00:26:24,880 --> 00:26:27,439
Speaker 1: story we told earlier. We start from a big cloud

598
00:26:27,520 --> 00:26:30,280
Speaker 1: of gas and dust and leftover bits from other solar

599
00:26:30,359 --> 00:26:33,159
Speaker 1: systems that have died and that collapses most of it

600
00:26:33,240 --> 00:26:35,919
Speaker 1: into the star, but like one percent of it stays

601
00:26:35,920 --> 00:26:39,000
Speaker 1: in this proto planetary disc, a bunch of heavy metals

602
00:26:39,000 --> 00:26:42,000
Speaker 1: and gas and dust and ice that is moving too

603
00:26:42,160 --> 00:26:44,800
Speaker 1: fast to fall into the stars. The star gobbles up

604
00:26:44,840 --> 00:26:48,280
Speaker 1: mostly gas and leaves behind this protoplanetary disc. And then

605
00:26:48,280 --> 00:26:51,840
Speaker 1: gravity does this thing. It starts from little seeding locations there,

606
00:26:51,840 --> 00:26:55,080
Speaker 1: little dots of heavy metal or little gravitational spots that

607
00:26:55,119 --> 00:26:57,760
Speaker 1: have over densities. Starts to cluster together other stuff, and

608
00:26:57,800 --> 00:27:00,000
Speaker 1: you get the string of rocks. So now instead of

609
00:27:00,160 --> 00:27:02,240
Speaker 1: having like a disc, you have a bunch of rings,

610
00:27:02,600 --> 00:27:05,520
Speaker 1: rings of these rocks of various sizes, which then gather

611
00:27:05,640 --> 00:27:09,320
Speaker 1: together and form stuff. And so one option is that

612
00:27:09,680 --> 00:27:11,720
Speaker 1: you know it forms into a planet. There's like one

613
00:27:11,720 --> 00:27:14,760
Speaker 1: dominant thing that pulls out all together into a planet.

614
00:27:14,960 --> 00:27:18,000
Speaker 1: Another option is that it just sort of stays a

615
00:27:18,080 --> 00:27:21,119
Speaker 1: ring of rocks because of tidal forces from neighboring planets

616
00:27:21,119 --> 00:27:23,480
Speaker 1: that prevent it from gathering together. But there's nothing that

617
00:27:23,600 --> 00:27:27,120
Speaker 1: says in physics that you couldn't have two objects coalescing.

618
00:27:27,600 --> 00:27:30,320
Speaker 1: You know that two things couldn't have pulled together sort

619
00:27:30,359 --> 00:27:33,679
Speaker 1: of an each other's lagrange points and ended up being

620
00:27:33,920 --> 00:27:36,760
Speaker 1: what looks like two planets, although you know the astronomers

621
00:27:36,760 --> 00:27:38,280
Speaker 1: would have said neither of them are planets.

622
00:27:38,400 --> 00:27:40,400
Speaker 3: Well, I feel like maybe we skipped the step there.

623
00:27:40,560 --> 00:27:43,320
Speaker 3: So you're saying, like the early Solar system was a

624
00:27:43,359 --> 00:27:46,399
Speaker 3: flat disc and then the stuff that was orbiting the

625
00:27:46,440 --> 00:27:51,320
Speaker 3: Sun or the new Sun kind of arrange itself into rings,

626
00:27:51,320 --> 00:27:54,679
Speaker 3: sort of like maybe Saturn's rings. So you can imagine

627
00:27:54,720 --> 00:27:57,040
Speaker 3: the Sun in the middle a bunch of rings, just

628
00:27:57,080 --> 00:28:00,000
Speaker 3: like Saturn has rings of rocks, and then those rings

629
00:28:00,119 --> 00:28:06,080
Speaker 3: eventually collapse into planets. Now, what's the process for that, Like,

630
00:28:06,160 --> 00:28:09,120
Speaker 3: what causes a ring of rocks to suddenly collapse into

631
00:28:09,280 --> 00:28:11,440
Speaker 3: a giant ball on one specific spot.

632
00:28:11,480 --> 00:28:14,760
Speaker 1: Well, that's gravity. Also, you know you have one spot

633
00:28:14,800 --> 00:28:17,600
Speaker 1: along the ring that's denser than another, and so it's

634
00:28:17,600 --> 00:28:20,439
Speaker 1: going to pull on stuff nearby, stuff that's ahead of it,

635
00:28:20,440 --> 00:28:22,199
Speaker 1: it's going to pull closer. The stuff that's behind it,

636
00:28:22,200 --> 00:28:24,320
Speaker 1: it's going to pull closer. And then as it gathers

637
00:28:24,359 --> 00:28:26,360
Speaker 1: more stuff, it's going to have more gravity. It's gonna

638
00:28:26,359 --> 00:28:29,199
Speaker 1: be able to reach further along that ring and essentially

639
00:28:29,280 --> 00:28:30,480
Speaker 1: grab that stuff together.

640
00:28:30,640 --> 00:28:32,680
Speaker 3: But I can see that for gathering the things around

641
00:28:32,680 --> 00:28:34,320
Speaker 3: it but what about the things that we're on, like

642
00:28:34,359 --> 00:28:35,640
Speaker 3: on the opposite side.

643
00:28:35,480 --> 00:28:36,879
Speaker 1: Of the ring. I think the answer is that we

644
00:28:36,920 --> 00:28:39,720
Speaker 1: aren't one hundred percent sure how that happens. We don't

645
00:28:39,760 --> 00:28:42,560
Speaker 1: know for example, if you can really form stuff on

646
00:28:42,640 --> 00:28:45,760
Speaker 1: the other side of the Solar System that stays there,

647
00:28:46,120 --> 00:28:49,440
Speaker 1: like for example, Jupiter's asteroids. Did those form? There is

648
00:28:49,480 --> 00:28:52,440
Speaker 1: an example of exactly what you're talking about, stuff forming

649
00:28:52,520 --> 00:28:55,560
Speaker 1: along that same ring and not getting absorbed into the

650
00:28:55,560 --> 00:28:59,040
Speaker 1: planet basically resisting because it's in a lagrange point and

651
00:28:59,080 --> 00:29:02,240
Speaker 1: it's gravity is to totally balanced. Or is that stuff

652
00:29:02,240 --> 00:29:05,080
Speaker 1: that came later? Did Jupiter actually clear its own path,

653
00:29:05,640 --> 00:29:07,600
Speaker 1: use up all the stuff in the ring, and then

654
00:29:07,680 --> 00:29:11,200
Speaker 1: later on stuff fell into Jupiter's legrange points. We just

655
00:29:11,240 --> 00:29:13,280
Speaker 1: don't know the answer to that. If stuff really can

656
00:29:13,480 --> 00:29:17,120
Speaker 1: form stably at the same time as a planet, that's

657
00:29:17,120 --> 00:29:18,320
Speaker 1: what you're asking, right.

658
00:29:18,200 --> 00:29:20,440
Speaker 3: Well, I think i'm asking like it once we had

659
00:29:20,480 --> 00:29:23,280
Speaker 3: a ring of rocks sort of like Saturn has rings.

660
00:29:23,680 --> 00:29:25,880
Speaker 3: Is it the case that each ring could only clasp

661
00:29:25,920 --> 00:29:28,880
Speaker 3: into one planet because of the bath Basically like the

662
00:29:28,960 --> 00:29:32,440
Speaker 3: math doesn't let you make more than one big planet

663
00:29:32,600 --> 00:29:34,480
Speaker 3: because anything else would be unstable.

664
00:29:34,560 --> 00:29:37,040
Speaker 1: No, the math would let you imagine a perfectly symmetric ring,

665
00:29:37,320 --> 00:29:40,960
Speaker 1: and then imagine like ten or twelve or fifty tiny

666
00:29:41,000 --> 00:29:43,600
Speaker 1: points perfectly spaced around that ring that are a little

667
00:29:43,600 --> 00:29:46,400
Speaker 1: bit heavier. Those would gather up all the stuff around them.

668
00:29:46,640 --> 00:29:49,080
Speaker 1: You'd end up with like ten or twelve or fifty

669
00:29:49,160 --> 00:29:52,840
Speaker 1: or whatever identically sized objects in an orbit around the Sun.

670
00:29:52,960 --> 00:29:55,880
Speaker 1: Physically and mathematically, it is nothing preventing that from happening.

671
00:29:55,960 --> 00:29:57,960
Speaker 1: I think the reason why it's not likely to happen

672
00:29:58,000 --> 00:30:00,720
Speaker 1: is that it requires a lot of symmetry balance for

673
00:30:00,760 --> 00:30:02,840
Speaker 1: that arrangement to get set up. It's much more likely

674
00:30:03,120 --> 00:30:04,560
Speaker 1: that one of them is bigger and one of them

675
00:30:04,600 --> 00:30:06,200
Speaker 1: is smaller, and then the bigger when it eats the

676
00:30:06,240 --> 00:30:06,840
Speaker 1: smaller one.

677
00:30:06,960 --> 00:30:08,960
Speaker 3: But I feel like you told me that before that

678
00:30:09,000 --> 00:30:12,520
Speaker 3: there's only like two stable spots around and stable orbit

679
00:30:13,040 --> 00:30:15,120
Speaker 3: where other things can be. You know, if I form

680
00:30:15,200 --> 00:30:18,400
Speaker 3: four miniplanets along the Earth's orbit, that wouldn't like some

681
00:30:18,480 --> 00:30:19,640
Speaker 3: of them be unstable.

682
00:30:19,760 --> 00:30:22,040
Speaker 1: It gets much more complicated as soon as you add

683
00:30:22,080 --> 00:30:24,520
Speaker 1: more than two objects. But no, you could have that

684
00:30:24,560 --> 00:30:26,920
Speaker 1: stable arrangement. You could have like a thousand planets in

685
00:30:26,960 --> 00:30:29,400
Speaker 1: a stable orbit around the Sun, as long as they're

686
00:30:29,480 --> 00:30:34,600
Speaker 1: perfectly equally spaced in equal mass. That's also allowed. Earlier,

687
00:30:34,640 --> 00:30:36,880
Speaker 1: we were just talking about the two planets around the Sun.

688
00:30:36,920 --> 00:30:38,719
Speaker 1: But if you allow them for more than two planets,

689
00:30:38,800 --> 00:30:41,280
Speaker 1: there's a lot more configurations you could have, but they're

690
00:30:41,280 --> 00:30:44,480
Speaker 1: also much more unstable, like they need to be perfectly

691
00:30:44,520 --> 00:30:47,280
Speaker 1: balanced in mass. In fact, I found some guy on

692
00:30:47,320 --> 00:30:49,320
Speaker 1: the web who's done a bunch of simulations of like

693
00:30:49,520 --> 00:30:50,840
Speaker 1: crazy solar systems.

694
00:30:51,000 --> 00:30:55,000
Speaker 2: You know, we have to say, some guy on the web, Yeah,

695
00:30:57,120 --> 00:30:59,760
Speaker 2: what this is? Okay?

696
00:31:00,040 --> 00:31:00,360
Speaker 6: Mm hmm.

697
00:31:00,560 --> 00:31:02,400
Speaker 1: I found some guy in the web who posted a

698
00:31:02,440 --> 00:31:06,600
Speaker 1: blog about simulations he had done about crazy solar systems

699
00:31:06,600 --> 00:31:09,960
Speaker 1: where you have like sixty jubiters in orbit around the

700
00:31:10,000 --> 00:31:13,440
Speaker 1: Sun and it's stable, Like if you arrange them perfectly,

701
00:31:13,760 --> 00:31:17,080
Speaker 1: sixty jupiters can stay in orbit around the Sun if

702
00:31:17,120 --> 00:31:18,280
Speaker 1: you set them up perfectly.

703
00:31:18,560 --> 00:31:20,800
Speaker 3: I see, I see. But how do you know he's right?

704
00:31:21,040 --> 00:31:24,120
Speaker 3: I mean, no offence. But if I told you that

705
00:31:24,240 --> 00:31:28,560
Speaker 3: some guy in the internet it's only something, would you

706
00:31:28,600 --> 00:31:29,440
Speaker 3: assume it's true?

707
00:31:29,720 --> 00:31:31,440
Speaker 1: No, But this one makes sense. I mean, just from

708
00:31:31,480 --> 00:31:34,520
Speaker 1: symmetry arguments, a ring could collapse and do a bunch

709
00:31:34,560 --> 00:31:37,360
Speaker 1: of objects as long as it does it symmetrically, then

710
00:31:37,400 --> 00:31:39,920
Speaker 1: it's still stable. Every one of those objects is the

711
00:31:39,920 --> 00:31:42,280
Speaker 1: same as any other objects, so it feels the same

712
00:31:42,320 --> 00:31:45,240
Speaker 1: gravity from all the other ones. They all cancel out essentially.

713
00:31:45,880 --> 00:31:48,200
Speaker 2: But I wonder how true that is. I don't know.

714
00:31:48,280 --> 00:31:49,920
Speaker 3: I mean not that I don't trust your guy on

715
00:31:49,960 --> 00:31:52,320
Speaker 3: the internet, but you know, at some point, maybe, like

716
00:31:52,360 --> 00:31:54,800
Speaker 3: if you have four things going around the Sun, maybe

717
00:31:54,840 --> 00:31:57,000
Speaker 3: the angles and the way they interact with each other,

718
00:31:57,040 --> 00:31:59,520
Speaker 3: and depending on how big they are, maybe it would

719
00:31:59,560 --> 00:32:00,000
Speaker 3: make it un.

720
00:32:00,640 --> 00:32:03,520
Speaker 1: I think it's a pretty simple extension of the argument

721
00:32:03,800 --> 00:32:06,520
Speaker 1: for why you don't feel gravity from anything that orbits

722
00:32:06,800 --> 00:32:09,040
Speaker 1: the Sun at like the same radius as you or

723
00:32:09,200 --> 00:32:11,800
Speaker 1: larger or for example, as you dig into the Earth,

724
00:32:11,960 --> 00:32:14,680
Speaker 1: you're not feeling gravity from layers of the Earth that

725
00:32:14,720 --> 00:32:16,840
Speaker 1: are larger than you because they all add up to

726
00:32:16,880 --> 00:32:19,000
Speaker 1: cancel out. There are fewer that are closer to you

727
00:32:19,040 --> 00:32:21,520
Speaker 1: and more that are further and they all balance out.

728
00:32:21,720 --> 00:32:25,000
Speaker 1: It's basically the same argument. It's like gravitational shell argument.

729
00:32:25,480 --> 00:32:27,800
Speaker 1: If you have a whole string of earths in orbit

730
00:32:27,880 --> 00:32:30,320
Speaker 1: with you, all of their gravity will cancel out.

731
00:32:30,360 --> 00:32:30,680
Speaker 2: All right.

732
00:32:30,720 --> 00:32:32,760
Speaker 3: Well, it sounds like we have a big mystery, which

733
00:32:32,840 --> 00:32:35,400
Speaker 3: is that it sounds like it's possible for two planets

734
00:32:35,400 --> 00:32:39,880
Speaker 3: to share an orbit definitions notwithstanding, But we don't really

735
00:32:39,880 --> 00:32:42,320
Speaker 3: see that in our solar system or maybe in other

736
00:32:42,480 --> 00:32:45,800
Speaker 3: solar systems out there in space. So let's dig a

737
00:32:45,800 --> 00:32:48,480
Speaker 3: little bit more into that mystery. But first, let's take

738
00:32:48,520 --> 00:33:03,760
Speaker 3: a quick break. All right, we're asking the question why

739
00:33:03,760 --> 00:33:07,960
Speaker 3: can't planets share? What's going on? Why are they so selfish?

740
00:33:08,040 --> 00:33:09,080
Speaker 1: It's the parent's fault.

741
00:33:09,600 --> 00:33:15,040
Speaker 3: It's always the parent's fault. But yeah, the planets like

742
00:33:15,080 --> 00:33:17,240
Speaker 3: to be loners. They don't like to share an orbit.

743
00:33:17,680 --> 00:33:20,120
Speaker 3: And we sort of know that mostly from what we

744
00:33:20,160 --> 00:33:22,880
Speaker 3: can see, right, because it sounds like theoretically it is

745
00:33:22,920 --> 00:33:26,360
Speaker 3: possible to have like two Earth orbiting or maybe for

746
00:33:26,560 --> 00:33:29,840
Speaker 3: Earth orbiting the same circle around the Sun. But we

747
00:33:30,000 --> 00:33:32,120
Speaker 3: just don't see that, and so the question is like

748
00:33:32,200 --> 00:33:32,520
Speaker 3: why not?

749
00:33:32,840 --> 00:33:36,480
Speaker 1: Yeah, I think that mathematically it's possible. If you set

750
00:33:36,600 --> 00:33:38,880
Speaker 1: up a solar system that way, you're like a solar

751
00:33:38,920 --> 00:33:41,560
Speaker 1: system builder, and you bring into Jupiter's and you align

752
00:33:41,640 --> 00:33:44,280
Speaker 1: them perfectly, you could build a solar system like that

753
00:33:44,320 --> 00:33:46,120
Speaker 1: which would be stable and last a long time.

754
00:33:46,400 --> 00:33:46,560
Speaker 6: You know.

755
00:33:46,600 --> 00:33:49,120
Speaker 1: The other question is would a solar system like that

756
00:33:49,280 --> 00:33:52,440
Speaker 1: form naturally? I think they're. The answer is that it's

757
00:33:52,480 --> 00:33:54,959
Speaker 1: most likely for things to collapse into one big planet,

758
00:33:55,120 --> 00:33:57,160
Speaker 1: or for things to not really collapse at all, like

759
00:33:57,240 --> 00:34:00,280
Speaker 1: Pluto or the asteroid belt because of tidal forces, or

760
00:34:00,280 --> 00:34:02,719
Speaker 1: they're just two distant gravity. And for things to collapse

761
00:34:02,760 --> 00:34:06,640
Speaker 1: into two really big or three big objects would require

762
00:34:06,680 --> 00:34:09,400
Speaker 1: a sort of a perfect symmetry where they like divide

763
00:34:09,480 --> 00:34:12,600
Speaker 1: up the mass budget into two or three portions and

764
00:34:12,680 --> 00:34:15,200
Speaker 1: each of them gather it up themselves. I think that

765
00:34:15,360 --> 00:34:17,920
Speaker 1: just requires a lot of balance for it to happen.

766
00:34:17,880 --> 00:34:20,160
Speaker 3: Like it basically a big coincidence you're saying. But I

767
00:34:20,160 --> 00:34:22,239
Speaker 3: guess maybe paint the scenario for us. So we have

768
00:34:22,440 --> 00:34:26,279
Speaker 3: initially around the young Sun sort of a ring of rocks.

769
00:34:26,320 --> 00:34:28,279
Speaker 3: Let's say, like there's a ring of rocks around where

770
00:34:28,280 --> 00:34:31,960
Speaker 3: Earth goes around the Sun in the Earth's orbit, and

771
00:34:32,080 --> 00:34:35,240
Speaker 3: maybe there's a little bit more more rocks in one spot,

772
00:34:35,280 --> 00:34:37,600
Speaker 3: and so that one starts to gather more things. But

773
00:34:37,640 --> 00:34:40,280
Speaker 3: there's a whole bunch of things all around the circle.

774
00:34:40,320 --> 00:34:42,239
Speaker 3: Does that mean like the things on the other side

775
00:34:42,280 --> 00:34:45,120
Speaker 3: of the orbit somehow speed up in order to catch

776
00:34:45,200 --> 00:34:48,239
Speaker 3: up to the Earth or slow down. What causes those

777
00:34:48,280 --> 00:34:50,600
Speaker 3: things to slow down or speed up, and if they did,

778
00:34:50,760 --> 00:34:52,800
Speaker 3: wouldn't they change orbits?

779
00:34:52,880 --> 00:34:55,440
Speaker 1: No, you're right, something on the other side of the Earth,

780
00:34:55,480 --> 00:34:59,600
Speaker 1: like perfectly opposed to the Earth feels no gravitational tug. Right,

781
00:34:59,640 --> 00:35:02,960
Speaker 1: the Earth cannot pull that thing into itself because it's

782
00:35:02,960 --> 00:35:05,759
Speaker 1: at a labraange point, right, So something that's there will

783
00:35:05,800 --> 00:35:08,680
Speaker 1: stay there. But that's a really tiny spot, the actual

784
00:35:08,800 --> 00:35:12,440
Speaker 1: exact lagrange point. Anything slightly ahead of it or slightly

785
00:35:12,520 --> 00:35:15,520
Speaker 1: behind it will feel a gravitational tug from the Earth,

786
00:35:15,560 --> 00:35:18,920
Speaker 1: and eventually the Earth will pull it into itself.

787
00:35:19,160 --> 00:35:21,440
Speaker 3: But it has to go all the way around the circle,

788
00:35:21,520 --> 00:35:24,200
Speaker 3: meaning like it speeds up in the orbit.

789
00:35:24,680 --> 00:35:27,040
Speaker 2: But if it speeds up, wouldn't it change orbits?

790
00:35:27,280 --> 00:35:29,839
Speaker 1: Yeah, that's possible. Also, the Earth could tug it, not

791
00:35:29,920 --> 00:35:31,759
Speaker 1: so that it ends up in the Earth, but that

792
00:35:31,840 --> 00:35:35,239
Speaker 1: it falls into another orbit or falls into the Sun. Right.

793
00:35:35,280 --> 00:35:37,480
Speaker 1: And remember that this is a very simplified way of

794
00:35:37,520 --> 00:35:39,840
Speaker 1: thinking about the Solar System, just one planet and the

795
00:35:39,880 --> 00:35:42,719
Speaker 1: Sun and one rock. In reality, there's lots of other

796
00:35:42,760 --> 00:35:45,480
Speaker 1: things going on there, so lots of chaotic tugs from

797
00:35:45,520 --> 00:35:48,239
Speaker 1: Jupiter and Mars as it passes by, so all sorts

798
00:35:48,239 --> 00:35:50,480
Speaker 1: of stuff disrupting this pile of rocks, some of them

799
00:35:50,520 --> 00:35:52,759
Speaker 1: falling out of this orbit and landing on Venus or

800
00:35:52,880 --> 00:35:55,200
Speaker 1: landing on Mars, or some of them ending up on Earth.

801
00:35:55,520 --> 00:35:57,919
Speaker 1: That's why Earth has rocks from all over the Solar

802
00:35:58,000 --> 00:36:00,359
Speaker 1: System that are landing on it, not just things from

803
00:36:00,440 --> 00:36:00,919
Speaker 1: our orbit.

804
00:36:01,360 --> 00:36:03,560
Speaker 3: Oh I see you're saying, like maybe the picture I

805
00:36:03,600 --> 00:36:05,719
Speaker 3: had of how planet's form is not quite correct, Like

806
00:36:06,160 --> 00:36:08,280
Speaker 3: you know, maybe to go from the equivalent of Saturn's

807
00:36:08,320 --> 00:36:10,799
Speaker 3: rings around the Sun to a planet, it doesn't mean

808
00:36:10,840 --> 00:36:13,399
Speaker 3: like a ring of rocks is kind of collapsed into

809
00:36:13,400 --> 00:36:16,600
Speaker 3: a planet, like Earth might be made out of the.

810
00:36:16,640 --> 00:36:17,760
Speaker 2: Rocks from different rings.

811
00:36:17,960 --> 00:36:18,840
Speaker 1: Absolutely it is.

812
00:36:19,120 --> 00:36:22,080
Speaker 2: Other planets might be made from rocks from other rings.

813
00:36:22,280 --> 00:36:25,640
Speaker 1: Absolutely, Yeah, there is is not just made from rocks

814
00:36:25,680 --> 00:36:29,719
Speaker 1: from one specific range of radii. Definitely, stuff has contributed

815
00:36:29,760 --> 00:36:32,920
Speaker 1: from the inner Solar System and from further out. Absolutely

816
00:36:32,960 --> 00:36:33,719
Speaker 1: there's a big mix.

817
00:36:34,000 --> 00:36:34,439
Speaker 2: Oh I see.

818
00:36:34,480 --> 00:36:36,120
Speaker 3: So like the history of the Solar System is that

819
00:36:36,160 --> 00:36:38,960
Speaker 3: it pour into a disc then rings. Then it was

820
00:36:39,280 --> 00:36:42,560
Speaker 3: a free for all or all the siblings for fighting

821
00:36:42,560 --> 00:36:45,640
Speaker 3: over who gets which toys and which rocks, and then

822
00:36:45,719 --> 00:36:50,600
Speaker 3: and then whoever was left victorious, whoever it was bigger

823
00:36:51,120 --> 00:36:54,360
Speaker 3: one exactly yeah, and whoever, I couldn't get along sleeping

824
00:36:54,400 --> 00:36:55,160
Speaker 3: outside in the tent.

825
00:36:55,440 --> 00:36:58,200
Speaker 1: And that's mostly the story. And to understand whether that's

826
00:36:58,200 --> 00:37:00,440
Speaker 1: the story the Solar system, we look around if there's

827
00:37:00,480 --> 00:37:02,560
Speaker 1: like weird stuff happening, you know, we'd love to have

828
00:37:02,640 --> 00:37:04,919
Speaker 1: seen two planets in the same orbit so we could

829
00:37:04,920 --> 00:37:07,280
Speaker 1: try to understand how that happened. There are some really

830
00:37:07,320 --> 00:37:10,879
Speaker 1: fascinating and interesting counter examples to this that we see

831
00:37:10,920 --> 00:37:14,720
Speaker 1: even in our own Solar system, like the moons of Saturn.

832
00:37:14,920 --> 00:37:16,320
Speaker 2: What do you mean, what's going on with the moons

833
00:37:16,320 --> 00:37:16,760
Speaker 2: of Saturn.

834
00:37:17,800 --> 00:37:20,040
Speaker 1: So Saturn's got lots of moons, and there's two in

835
00:37:20,080 --> 00:37:25,319
Speaker 1: particular that swap orbits. So there's the moon Janus and

836
00:37:25,360 --> 00:37:29,080
Speaker 1: then there's the moon Epimetheus, and these two swap orbits

837
00:37:29,160 --> 00:37:32,719
Speaker 1: every four years. Like Janus is on the outside and

838
00:37:32,760 --> 00:37:35,720
Speaker 1: Epimetheus is on the inside, which has a short orbit

839
00:37:36,040 --> 00:37:39,440
Speaker 1: and it comes really close to Janus and tugs on it,

840
00:37:39,640 --> 00:37:42,760
Speaker 1: and the gravitational interaction means that they end up swapping.

841
00:37:42,840 --> 00:37:45,799
Speaker 1: So now Genus is on the inside and Epimetheus is

842
00:37:45,800 --> 00:37:47,400
Speaker 1: on the outside.

843
00:37:46,920 --> 00:37:49,440
Speaker 3: Well, well do they swap orbits or it's just that

844
00:37:49,480 --> 00:37:52,560
Speaker 3: they both have really complicated orbits that overlap each other.

845
00:37:52,719 --> 00:37:55,400
Speaker 1: Well, there's two different radii and for four years, one

846
00:37:55,400 --> 00:37:56,719
Speaker 1: of them has the inner one and the other one

847
00:37:56,760 --> 00:37:58,600
Speaker 1: has the outer one, and then they swap. So you

848
00:37:58,600 --> 00:38:00,560
Speaker 1: can think about it two ways, like one is they

849
00:38:00,600 --> 00:38:03,440
Speaker 1: have different lanes and they're changing lanes, or you could

850
00:38:03,440 --> 00:38:05,520
Speaker 1: think about it in the more general sense, like each

851
00:38:05,600 --> 00:38:07,960
Speaker 1: moon does four laps on the outer one and then

852
00:38:08,000 --> 00:38:10,600
Speaker 1: four laps on the inner one, and they're perfectly synced

853
00:38:10,840 --> 00:38:12,439
Speaker 1: to never be on top of each other.

854
00:38:13,040 --> 00:38:15,640
Speaker 3: And the reason they change lanes is from the where

855
00:38:15,680 --> 00:38:18,000
Speaker 3: they interact with each other, or just the way they

856
00:38:18,000 --> 00:38:19,160
Speaker 3: interact with Saturn, the.

857
00:38:19,080 --> 00:38:21,279
Speaker 1: Way they interact with each other, like the one on

858
00:38:21,280 --> 00:38:23,279
Speaker 1: the inner lane catches up to the one on the

859
00:38:23,280 --> 00:38:26,400
Speaker 1: outer lane and tugs on it, pulling it in, and

860
00:38:26,440 --> 00:38:29,920
Speaker 1: the gravitational interaction pushes the one from the inner lane out.

861
00:38:30,239 --> 00:38:33,440
Speaker 3: Well, meaning sort of like a younger sibling who's motivated

862
00:38:33,480 --> 00:38:36,600
Speaker 3: to catch up to its older sibling and then or

863
00:38:36,760 --> 00:38:38,080
Speaker 3: takes it for four years.

864
00:38:38,360 --> 00:38:40,799
Speaker 1: What else motivates younger siblings If not that, I mean

865
00:38:40,880 --> 00:38:41,960
Speaker 1: that's basically it, right.

866
00:38:43,080 --> 00:38:45,720
Speaker 3: Wait, are you trying to take credit for your brother's accomplishments?

867
00:38:45,800 --> 00:38:47,720
Speaker 3: Is this what this is all about.

868
00:38:48,360 --> 00:38:48,719
Speaker 1: That's right?

869
00:38:48,920 --> 00:38:50,880
Speaker 3: Is this why this whole episode is just the far

870
00:38:51,040 --> 00:38:53,760
Speaker 3: you to take some of your brother's glory.

871
00:38:54,000 --> 00:38:56,960
Speaker 1: My entire life is just nothing but setting the stage

872
00:38:56,960 --> 00:38:58,279
Speaker 1: to take credit from a younger brother.

873
00:38:59,480 --> 00:39:02,239
Speaker 3: That's all right, Yeah, okay, you're trying to overtake him

874
00:39:02,239 --> 00:39:04,000
Speaker 3: and steal his orbit.

875
00:39:04,280 --> 00:39:06,919
Speaker 1: Yeah. The whole thing is a fifty year long con man.

876
00:39:08,600 --> 00:39:11,640
Speaker 2: The whole thing is a therapy session.

877
00:39:11,680 --> 00:39:13,960
Speaker 1: I feel like, Oh, in the end, you know, you're

878
00:39:14,000 --> 00:39:16,920
Speaker 1: defined by the circumstances in which you're born, just like

879
00:39:17,000 --> 00:39:21,320
Speaker 1: Saturn and Janus and Epimetheus doomed to do this dance forever.

880
00:39:21,680 --> 00:39:24,360
Speaker 1: But it's really fascinating to see this like every four years.

881
00:39:24,560 --> 00:39:26,800
Speaker 1: And it's a funny story because when these moons were discovered,

882
00:39:26,840 --> 00:39:29,280
Speaker 1: they didn't realize there were actually two moons there basically

883
00:39:29,320 --> 00:39:31,640
Speaker 1: in the same orbit. They saw one, and then somebody

884
00:39:31,640 --> 00:39:33,920
Speaker 1: else was looking at that moon and realizing, huh, this

885
00:39:34,080 --> 00:39:36,440
Speaker 1: doesn't look like the same moon that was previously reported,

886
00:39:36,600 --> 00:39:39,000
Speaker 1: but it's in the right orbit. What's going on? And

887
00:39:39,080 --> 00:39:41,239
Speaker 1: took people a while to figure out, actually the two

888
00:39:41,280 --> 00:39:43,320
Speaker 1: moons here that are swapping orbits?

889
00:39:43,640 --> 00:39:46,400
Speaker 3: Whoa and does the swapping happen like really fast or

890
00:39:46,440 --> 00:39:47,560
Speaker 3: over years as well.

891
00:39:47,760 --> 00:39:50,319
Speaker 1: The swapping happens pretty fast. I mean it's every four

892
00:39:50,400 --> 00:39:53,799
Speaker 1: years that happens, but the swap itself doesn't take years.

893
00:39:54,040 --> 00:39:56,319
Speaker 3: And could something like that happen elsewhere or is this

894
00:39:56,400 --> 00:39:58,680
Speaker 3: like a super duper bizarre circumstance.

895
00:39:58,920 --> 00:40:01,319
Speaker 1: It's a pretty bizarre sir cumstance. You need exactly the

896
00:40:01,440 --> 00:40:04,640
Speaker 1: right radii and exactly the right masses. We also don't

897
00:40:04,680 --> 00:40:07,360
Speaker 1: know how long it can go on for. You know,

898
00:40:07,400 --> 00:40:10,640
Speaker 1: it's pretty chaotic, and so it seems like something else

899
00:40:10,680 --> 00:40:12,759
Speaker 1: passing nearby gives just the right tug and one of

900
00:40:12,840 --> 00:40:15,600
Speaker 1: these things just plummets into Jupiter. But it's an example

901
00:40:15,680 --> 00:40:19,359
Speaker 1: of how really weird, rare stuff can happen in the

902
00:40:19,360 --> 00:40:21,719
Speaker 1: Solar system. And it might mean that even if two

903
00:40:21,800 --> 00:40:24,959
Speaker 1: big planets forming in the same orbit seems unlikely because

904
00:40:24,960 --> 00:40:27,440
Speaker 1: you need just the right balance, it might happen. It

905
00:40:27,520 --> 00:40:30,480
Speaker 1: might happen in other solar systems. It might happen more

906
00:40:30,520 --> 00:40:31,560
Speaker 1: than we even expect.

907
00:40:31,719 --> 00:40:33,560
Speaker 3: Well, it sounds like it might happen just from how

908
00:40:33,640 --> 00:40:37,759
Speaker 3: random and chaotic the you know, young Solar system is, right, Like,

909
00:40:38,000 --> 00:40:39,920
Speaker 3: you know, maybe you wouldn't get two plants from the

910
00:40:39,920 --> 00:40:42,160
Speaker 3: same ring of rocks. But maybe, you know, you could

911
00:40:42,200 --> 00:40:44,960
Speaker 3: get the Earth and then something like Mars drifts into

912
00:40:45,000 --> 00:40:48,040
Speaker 3: our orbit or something, or we swap orbits with Mars,

913
00:40:48,120 --> 00:40:51,080
Speaker 3: just like these two moons. That's totally possible, right.

914
00:40:50,960 --> 00:40:53,719
Speaker 1: It's totally possible, And some people think that something like

915
00:40:53,760 --> 00:40:57,040
Speaker 1: that might have been a cause for the collision actually

916
00:40:57,040 --> 00:41:00,279
Speaker 1: between the proto Moon and the proto Earth. The theory

917
00:41:00,280 --> 00:41:02,280
Speaker 1: of the Moon's formation is that there were two proto

918
00:41:02,360 --> 00:41:04,759
Speaker 1: planets that slammed into each other that formed the Earth

919
00:41:04,760 --> 00:41:06,879
Speaker 1: in the Moon, and it could have been like two

920
00:41:06,880 --> 00:41:09,200
Speaker 1: planets that formed separately and then got too close to

921
00:41:09,280 --> 00:41:11,680
Speaker 1: each other, or maybe they were in each one of

922
00:41:11,719 --> 00:41:14,000
Speaker 1: each other's lagrange points for a while, but it wasn't

923
00:41:14,080 --> 00:41:15,800
Speaker 1: stable and then it ended up colliding.

924
00:41:15,920 --> 00:41:17,880
Speaker 3: And it sounds like it could still happen maybe in

925
00:41:17,920 --> 00:41:20,520
Speaker 3: our Solar system, Like you know, those meteors that are

926
00:41:20,680 --> 00:41:23,399
Speaker 3: orbiting with Jupiter ahead and behind it, those could kind

927
00:41:23,400 --> 00:41:26,239
Speaker 3: of maybe cluster together into something that might look like

928
00:41:26,239 --> 00:41:27,160
Speaker 3: a planet, couldn't they.

929
00:41:27,280 --> 00:41:30,239
Speaker 1: Yeah, eventually they might unionize and work together and form

930
00:41:30,280 --> 00:41:32,840
Speaker 1: their own planet, and then they could protest Jupiter and

931
00:41:32,920 --> 00:41:36,000
Speaker 1: they could get Jupiter demoted from being a planet or

932
00:41:36,040 --> 00:41:40,640
Speaker 1: Pluto upgraded. You never know once you start an astronomical

933
00:41:40,719 --> 00:41:41,640
Speaker 1: lawsuit what happens.

934
00:41:41,719 --> 00:41:44,719
Speaker 3: Right, it might be like a planetary conspiracy and they

935
00:41:44,800 --> 00:41:46,680
Speaker 3: all get you know, sued together.

936
00:41:48,160 --> 00:41:50,040
Speaker 1: Maybe we just get rid of this whole name for

937
00:41:50,120 --> 00:41:52,800
Speaker 1: a planet. We just stuff out there, man.

938
00:41:52,640 --> 00:41:56,040
Speaker 3: Unless you just call them, yeah, rocks, big floating rocks,

939
00:41:56,280 --> 00:41:57,440
Speaker 3: unless they're made out of gas.

940
00:41:57,480 --> 00:42:01,319
Speaker 1: Oh no, there's big planets the size of the.

941
00:42:01,400 --> 00:42:05,760
Speaker 3: Balls, just calling balls if it's circular, and as southern space,

942
00:42:06,120 --> 00:42:07,720
Speaker 3: just call space balls.

943
00:42:07,480 --> 00:42:09,680
Speaker 1: I know. And they even require these things to be spherical,

944
00:42:09,719 --> 00:42:11,799
Speaker 1: and none of them actually are sphericle, right, even the

945
00:42:11,800 --> 00:42:13,560
Speaker 1: Earth is not technically spherical.

946
00:42:13,760 --> 00:42:16,799
Speaker 3: Oh boy, so it's a lawsuit waiting to happen. Well,

947
00:42:16,840 --> 00:42:19,759
Speaker 3: how about out there beyond our Solar system? You know

948
00:42:19,880 --> 00:42:23,719
Speaker 3: now we can see with our telescopes really far away

949
00:42:23,800 --> 00:42:27,360
Speaker 3: distant stars and distant planets. Have we seen two planets

950
00:42:27,360 --> 00:42:29,880
Speaker 3: share in orbit out there in the wider universe?

951
00:42:30,200 --> 00:42:32,920
Speaker 1: We have not yet seen it, and we've looked. You know,

952
00:42:32,960 --> 00:42:36,480
Speaker 1: we are pretty good at seeing planets around stars in

953
00:42:36,600 --> 00:42:40,000
Speaker 1: other solar systems in some scenarios. And we can tell

954
00:42:40,080 --> 00:42:42,840
Speaker 1: because those planets like orbit the star and eclipse it,

955
00:42:43,080 --> 00:42:44,839
Speaker 1: or they tug on the star, and we can tell

956
00:42:44,840 --> 00:42:47,799
Speaker 1: about the change and the light from the star. And

957
00:42:47,920 --> 00:42:50,640
Speaker 1: so it's looking for the wobble in the star and

958
00:42:50,680 --> 00:42:53,279
Speaker 1: dips in its brightness that give us clues. And from

959
00:42:53,320 --> 00:42:55,080
Speaker 1: those dips or from those wobbles, we can get a

960
00:42:55,160 --> 00:42:58,120
Speaker 1: sensul like the period of the planet. And so far

961
00:42:58,239 --> 00:43:01,279
Speaker 1: we've never seen like two waters or dips with the

962
00:43:01,320 --> 00:43:06,000
Speaker 1: same period that would indicate like co orbiting planets. So

963
00:43:06,000 --> 00:43:07,919
Speaker 1: so far we haven't seen anything like that.

964
00:43:08,160 --> 00:43:10,200
Speaker 3: I feel like maybe there's something else going on here,

965
00:43:10,320 --> 00:43:13,600
Speaker 3: maybe something that physicists haven't thought about, because it seems possible,

966
00:43:13,840 --> 00:43:18,240
Speaker 3: it seems sort of not impossible. And given so many

967
00:43:18,680 --> 00:43:21,960
Speaker 3: planets and asteroids and things out there floating in space

968
00:43:22,040 --> 00:43:25,000
Speaker 3: in our Solar system, and also all of the trillions

969
00:43:25,000 --> 00:43:27,120
Speaker 3: of Solar systems we can see out there that we

970
00:43:27,160 --> 00:43:29,480
Speaker 3: haven't seen one, it seems like there's something going on.

971
00:43:30,160 --> 00:43:33,560
Speaker 1: There's a conspiracy. Remember that we've looked at only several

972
00:43:33,640 --> 00:43:36,520
Speaker 1: thousand stars to see if there are planets around them,

973
00:43:36,560 --> 00:43:39,240
Speaker 1: and there's billions and billions of stars in the galaxy.

974
00:43:39,320 --> 00:43:41,560
Speaker 1: That might mean that it's unlikely and not that common,

975
00:43:41,640 --> 00:43:43,640
Speaker 1: but it doesn't mean it doesn't happen. In fact, there

976
00:43:43,640 --> 00:43:46,719
Speaker 1: are astronomers that used a radio array in Chile to

977
00:43:46,760 --> 00:43:49,680
Speaker 1: look at a planetary system that's still forming. There's a

978
00:43:49,719 --> 00:43:52,280
Speaker 1: young star like three hundred and seventy light years from Earth,

979
00:43:52,480 --> 00:43:55,279
Speaker 1: and it's not done making its planets, like they see

980
00:43:55,280 --> 00:43:57,920
Speaker 1: exoplanets forming around it, but it's still got a really

981
00:43:57,960 --> 00:44:02,320
Speaker 1: big disc of protoplanetary stuff. And when they studied this system,

982
00:44:02,400 --> 00:44:04,920
Speaker 1: they found a big blob of dust in one of

983
00:44:04,960 --> 00:44:08,640
Speaker 1: the lagrange points near that exoplanet. So that might be

984
00:44:08,840 --> 00:44:11,960
Speaker 1: like a coplanet that's forming, or it could be that

985
00:44:12,040 --> 00:44:15,200
Speaker 1: whatever this conspiracy is, you know, breaks that up before.

986
00:44:15,000 --> 00:44:17,680
Speaker 3: It can happen, Like maybe it's not as stable as

987
00:44:17,719 --> 00:44:19,879
Speaker 3: you think it is or something. That's what you're saying.

988
00:44:19,920 --> 00:44:24,040
Speaker 1: Right, Maybe it's technically possible, but this requires such ridiculous

989
00:44:24,080 --> 00:44:27,319
Speaker 1: balance between all the factors that's never practically achieved in

990
00:44:27,320 --> 00:44:27,880
Speaker 1: the universe.

991
00:44:28,280 --> 00:44:29,680
Speaker 3: All right, well, it sounds like maybe the answer to

992
00:44:29,760 --> 00:44:32,120
Speaker 3: the question of why don't you have two planets sharing

993
00:44:32,120 --> 00:44:33,960
Speaker 3: in orbit. The answers that are like, we don't know.

994
00:44:34,440 --> 00:44:37,239
Speaker 3: It seems possible, but we just haven't seen it yet.

995
00:44:37,320 --> 00:44:40,080
Speaker 1: Yeah, it seems possible. It might just require a very

996
00:44:40,200 --> 00:44:43,160
Speaker 1: very special set of circumstances that we just haven't had

997
00:44:43,160 --> 00:44:45,400
Speaker 1: a chance to see yet. But as you look deeper

998
00:44:45,400 --> 00:44:48,600
Speaker 1: into the universe, everything that's possible, everything that's weird, I

999
00:44:48,600 --> 00:44:49,840
Speaker 1: think eventually.

1000
00:44:49,440 --> 00:44:53,560
Speaker 3: You will see, like two brothers that get along statistically,

1001
00:44:53,560 --> 00:44:55,800
Speaker 3: it might happen two.

1002
00:44:55,719 --> 00:44:58,279
Speaker 1: Brothers that are professors at exactly the same level of

1003
00:44:58,280 --> 00:44:59,360
Speaker 1: prestigious university.

1004
00:44:59,440 --> 00:44:59,920
Speaker 2: There you go.

1005
00:45:00,200 --> 00:45:03,759
Speaker 3: Make it all depends on their intent. All right, Well,

1006
00:45:04,160 --> 00:45:07,399
Speaker 3: we hope you enjoyed that. Thanks for joining us. See

1007
00:45:07,440 --> 00:45:08,000
Speaker 3: you next time.

1008
00:45:12,600 --> 00:45:15,480
Speaker 1: For more science and curiosity, come find us on social

1009
00:45:15,520 --> 00:45:20,400
Speaker 1: media where we answer questions and post videos. We're on Twitter, Discord, Insta,

1010
00:45:20,520 --> 00:45:23,960
Speaker 1: and now TikTok. Thanks for listening, and remember that Daniel

1011
00:45:24,000 --> 00:45:27,759
Speaker 1: and Jorge Explain the Universe is a production iHeartRadio. For

1012
00:45:27,960 --> 00:45:32,879
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1013
00:45:33,000 --> 00:45:35,360
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