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Did Jupiter once have a different orbit? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Kelly, how do you feel about moving? It always
0:13
Speaker 1: seems like it's going to be exciting, but it's always
0:15
Speaker 1: a drag. No. Right, It's like there's always one more
0:19
Speaker 1: box of stuff, and by mathematical induction, that means we
0:23
Speaker 1: all have infinite totally checks out. I mean I have
0:26
Speaker 1: like infinite back pain from my last move. Sometimes I
0:30
Speaker 1: wish I had a mobile home so that I wouldn't
0:32
Speaker 1: have to pack everything up every time. That is a
0:34
Speaker 1: genius solution. I mean, you move more stuff, but you
0:37
Speaker 1: do less work because you take your whole house with
0:39
Speaker 1: you exactly. I wonder if it's scales. I'm thinking like
0:44
Speaker 1: mobile neighborhoods, mobile cities, maybe like mobile planets. Earth is
0:49
Speaker 1: just one big mobile home. Man, I didn't realize we
0:52
Speaker 1: lived in a cosmic trailer park. I'm Daniel, I'm a
1:11
Speaker 1: particle physicist, and I once moved across the Atlantic eleven
1:16
Speaker 1: times in four years. Seriously, seriously. This was when I
1:21
Speaker 1: was a junior professor and just getting started at the
1:24
Speaker 1: Large Hadron Collider and teaching on the West coast of
1:27
Speaker 1: the United States. So we actually had a house in
1:29
Speaker 1: France and a house in California, and we had to
1:31
Speaker 1: go back and forth and back and forth, and back
1:33
Speaker 1: and forth and back and forth and back and forth.
1:35
Speaker 1: It almost drove my family crazy. Oh my gosh, did
1:37
Speaker 1: you have kids at that point? We had two young children,
1:40
Speaker 1: one of the whom was born in Switzerland. Oh my goodness.
1:44
Speaker 1: I know. It's amazing I'm not divorced. It is. It is.
1:48
Speaker 1: I shouldn't have said it is so quickly, but well,
1:51
Speaker 1: I'm Kelly Wiener Smith and I'm a parasitologist, and it's
1:54
Speaker 1: amazing that I'm not divorced. Also because I moved my
1:56
Speaker 1: husband four times during my PhD to different states. But
2:00
Speaker 1: you know, I used to think that was bad. And
2:02
Speaker 1: now I'm going to go downstairs and tell Zack later
2:04
Speaker 1: how easy he has it. So thank you for that.
2:06
Speaker 1: That's good. That's my goal is to make other marriages
2:09
Speaker 1: look good. We appreciate it. Well. Welcome to the podcast
2:14
Speaker 1: Daniel and Jorge Explain the Universe, in which we talk
2:17
Speaker 1: about all the crazy and amazing things that we find
2:20
Speaker 1: out there in the universe, moving here and there, taking
2:22
Speaker 1: our brains from the tiniest little particles down to the
2:25
Speaker 1: quantum realm to the vast planets of the outer Solar
2:28
Speaker 1: system and all the way to super clusters. Our goal
2:32
Speaker 1: is to embrace everything we know and that we don't
2:35
Speaker 1: know and explain all of it to you. And as
2:38
Speaker 1: you might have guests today on the program, Jorge is
2:40
Speaker 1: not here, so we have our fabulous guest host, Kelly
2:43
Speaker 1: Weener Smith joining us to talk about all these things
2:46
Speaker 1: and ask good questions. Hey, Daniel, I'm excited to be back.
2:49
Speaker 1: I had fun lost time. Awesome, great, well, thanks very
2:52
Speaker 1: much for joining us. So we started off joking about
2:55
Speaker 1: moving houses and moving planets. But this is something I
2:58
Speaker 1: think is actually really interesting, is thinking about how the
3:02
Speaker 1: planets in our solar system got where they are and
3:05
Speaker 1: whether or not they have ever moved. I personally love
3:08
Speaker 1: this question because it's one of those questions that, like
3:11
Speaker 1: the fact that we have anything that even vaguely resembles
3:13
Speaker 1: an answer, makes me sort of proud to be a human. Like,
3:16
Speaker 1: how can we even think about these sorts of questions
3:18
Speaker 1: and collect data to answer these questions. It just seems
3:21
Speaker 1: so mind blowing to begin with the fact that we
3:23
Speaker 1: have any answers, even preliminary answers, blows my mind. Well,
3:26
Speaker 1: I think it's super fascinating that we even know to
3:29
Speaker 1: ask these questions, right, Like, you look at the Solar
3:32
Speaker 1: system and we have the planets, and they don't seem
3:35
Speaker 1: to be changing from year to year. We have thousands
3:37
Speaker 1: of years of astronomical records and so it seems sort
3:40
Speaker 1: of stable. So it's sort of absurd even to ask, like,
3:44
Speaker 1: could the planets have ever been in another configuration? Could
3:48
Speaker 1: the solar system have looked different? It's like very natural
3:51
Speaker 1: to think, oh, things are going around the Sun. They've
3:53
Speaker 1: been going around the Sun. Of course they were always
3:55
Speaker 1: in the same orientation. But something that's happened over the
3:59
Speaker 1: last just couple of decades is that we've had a
4:02
Speaker 1: chance to glimpse other solar systems. For thousands of years,
4:06
Speaker 1: we've only ever seen ours. We had like one example.
4:09
Speaker 1: Now we're seeing lots and lots of other solar systems,
4:12
Speaker 1: and this gives us a clue that solar systems can
4:15
Speaker 1: look different and that there might be a lot of activity,
4:18
Speaker 1: that they're actually quite volatile. That is super exciting. So
4:21
Speaker 1: for our sample size for these like how many solar
4:23
Speaker 1: systems can we see in enough detail where we can
4:25
Speaker 1: like count all of the planets and get a bit
4:27
Speaker 1: of a sense for what those planets are, like, are
4:29
Speaker 1: we talking hundreds, thousands, millions? How big is our data
4:32
Speaker 1: set here? It's exciting because it's growing so rapidly, Like
4:36
Speaker 1: the first exoplanets were discovered just a few decades ago,
4:39
Speaker 1: and now we have thousands, not yet millions. Someday astronomers
4:43
Speaker 1: will get to play with the datas that have millions
4:45
Speaker 1: of solar systems and ask really detailed questions. But we
4:47
Speaker 1: have thousands of solar systems that we can look at
4:50
Speaker 1: and we see weird stuff in those solar systems that
4:53
Speaker 1: we don't see in our solar system and that makes
4:55
Speaker 1: us wonder, like, wait a second, are those solar systems weird?
4:58
Speaker 1: Or is our Solar system weird? I need to know
5:00
Speaker 1: the answer, And so today on the podcast will be
5:04
Speaker 1: asking the question has our Solar system look different? In particular,
5:14
Speaker 1: did Jupiter ones have a different orbit? And that's a
5:18
Speaker 1: pretty huge question, right because Jupiter is like the biggest
5:20
Speaker 1: planet out there, so where it goes has a big impact.
5:23
Speaker 1: From one point of view, you could imagine it's basically
5:25
Speaker 1: the only planet other than the Sun. Jupiter has like
5:29
Speaker 1: of all the mass in the Solar system. Everything else
5:32
Speaker 1: is basically a detail compared to Jupiter. So yeah, it's
5:35
Speaker 1: a big deal. If Jupiter had been in a different place,
5:38
Speaker 1: everything would be different, and so as usual, I was
5:41
Speaker 1: curious whether people had this in their minds, like, have
5:45
Speaker 1: people imagine the possibility that Jupiter could be in a
5:48
Speaker 1: different place? Is that something people have thought about, have
5:50
Speaker 1: heard about? So I went out there to the wilds
5:53
Speaker 1: of the Internet and I asked people, Hey, do you
5:56
Speaker 1: know the answer to this tough physics question that astronomers
5:58
Speaker 1: are struggling over. Use no preparation, no googling allowed, Just
6:02
Speaker 1: tell me off the top of your head. Here's what
6:04
Speaker 1: people had to say. I guess No, there were impacts
6:10
Speaker 1: off I guess asteroids and or comets, and I may
6:17
Speaker 1: be even bigger objects in the past. So I think
6:22
Speaker 1: the orbit of Jupiter was a different one two beion
6:28
Speaker 1: years ago. No, I think it was, but I think
6:31
Speaker 1: it used to be a lot closer and then it
6:34
Speaker 1: moved out through collisions and the collisions, I think Jupiter
6:39
Speaker 1: used to be in a different orbit. I know Uranus
6:43
Speaker 1: rotates about its access in a way that sideways compared
6:47
Speaker 1: to the other planets. Well, I'm not sure if what
6:51
Speaker 1: I think happened, is that Uranus and Jupiter collies at
6:55
Speaker 1: some point. I suspect that Jupiter has been in its
6:58
Speaker 1: current orbit for quite some time, speaking on you know,
7:04
Speaker 1: the scale of the formation of our Solar system, but
7:07
Speaker 1: I would not at all be surprised if it had
7:10
Speaker 1: moved around somewhat during the early formation period of our
7:13
Speaker 1: solar system. Would say, yes, well, nothing is permanent, so
7:20
Speaker 1: I guess it's at the origin it was part of
7:23
Speaker 1: the the Sun or giant cloud of gas. But to me, well,
7:30
Speaker 1: it's quite stable orbits, and I don't see why each change,
7:35
Speaker 1: except for minor changes such as a collision with that
7:39
Speaker 1: other objects. But I would say yes, no, no, Um.
7:45
Speaker 1: Jupiter at some point was sitting towards the Sun, but
7:51
Speaker 1: it's kinda got locked in by Saturn, probably interaction with
8:01
Speaker 1: settled um, something like that. I don't know, you caught me.
8:08
Speaker 1: I'll guard here. I don't think that Jupiter has always
8:11
Speaker 1: been in its current orbit. I think it formed much
8:13
Speaker 1: closer to the Sun, and as it migrated out into
8:17
Speaker 1: the Solar System, it cleared a lot of the debris
8:19
Speaker 1: and comets and asteroids and dust and everything out of
8:24
Speaker 1: its way um and made things a little bit more
8:26
Speaker 1: stable here in the inner Solar system, so life could form.
8:30
Speaker 1: But I don't think that it started out where it
8:32
Speaker 1: currently is. Somebody say no, but I guess, being it's
8:35
Speaker 1: so big, it could well have picked up a lot
8:38
Speaker 1: of stuff through its time, and as it um, you know,
8:42
Speaker 1: it picks up more stuff gets impacted, and I guess
8:45
Speaker 1: it's gravitational forces would interact with other planets and stuff around,
8:49
Speaker 1: so therefore it get knocked off and moved off its
8:52
Speaker 1: little but quite regularly. Maybe, I think almost certainly no. UM.
8:57
Speaker 1: I think the current model of how those those system
9:00
Speaker 1: was formed UM actually relies on Jupiter migrating inward closer
9:07
Speaker 1: to the Sun and then further away. I believe Jupiter
9:11
Speaker 1: has moved from its original orbit. I think the original
9:15
Speaker 1: orbit was closer to the Sun. All right, Wow, those
9:18
Speaker 1: are some great answers from our listeners. When you heard
9:22
Speaker 1: that this was even a question that people were thinking about,
9:26
Speaker 1: did you have a like, oh my gosh moment or
9:29
Speaker 1: did it just seem like an obvious question for you
9:31
Speaker 1: to be asking. I had an oh my gosh moment
9:34
Speaker 1: and a hope because I thought, oh, that would be
9:37
Speaker 1: super cool if Jupiter wasn't always in its current orbit.
9:41
Speaker 1: Because one of the fun things for me in science
9:43
Speaker 1: is revealing surprises. Right If you ask a question and
9:46
Speaker 1: then the answer is yeah, it's kind of boring Jupiter
9:49
Speaker 1: has always been there. That's not nearly as fun as
9:51
Speaker 1: Oh my gosh, it turns out there's a crazy history
9:54
Speaker 1: here and we have revealed it. Like you were saying earlier,
9:56
Speaker 1: it's incredible that we could, like by gathering small lose
10:00
Speaker 1: left by these crazy cosmic events, actually reconstruct something that
10:05
Speaker 1: happened billions of years ago. It's like solving a billion
10:08
Speaker 1: year old murder mystery. As a biologist, every once in
10:10
Speaker 1: a while we will have discussions about like what makes
10:13
Speaker 1: humans different than other animals, And you know, clearly being
10:16
Speaker 1: able to think about questions like this is one of
10:19
Speaker 1: those things that like, certainly we're the only species who's
10:22
Speaker 1: wondering that on our planet exactly. So it's super fun.
10:27
Speaker 1: And I was really hoping that the answer would be
10:29
Speaker 1: something crazy. So it's pretty interesting to learn about. And
10:32
Speaker 1: I've also really been enjoying following this Excel planet discovery
10:37
Speaker 1: seeing these other solar systems, these other like potential homes
10:41
Speaker 1: for aliens where life could be really different because the
10:43
Speaker 1: planets are so different from ours. You know, we're sort
10:46
Speaker 1: of like trapped in this colloquial way of thinking that
10:49
Speaker 1: our kinds of planets are the kinds of planets you have,
10:52
Speaker 1: like small rocky planets and the inner Solar system and
10:55
Speaker 1: big gas giants and the outside and now it's possible
10:57
Speaker 1: to imagine other kinds of areas. So is our configuration
11:02
Speaker 1: a typical configuration. It turns out it's not. When we
11:05
Speaker 1: look at other solar systems, we see something really weird.
11:08
Speaker 1: First of all, we see that most solar systems have
11:11
Speaker 1: a lot more planets very close to their star, Like
11:14
Speaker 1: between Mercury and the Sun there's basically nothing, But in
11:18
Speaker 1: other solar systems there are lots of planets packed in there.
11:21
Speaker 1: And in particular, we find these things called hot jupiters.
11:25
Speaker 1: Not hot because they're like you know, big on Instagram
11:27
Speaker 1: or they're really curvy, hot because they're really close to
11:31
Speaker 1: the Sun. Like, we find these planets in other solar
11:34
Speaker 1: systems that are really big, like Jupiter size and gas planets,
11:39
Speaker 1: but they orbit the star in just like hours or days,
11:42
Speaker 1: and like a fraction of the distance between the Sun
11:45
Speaker 1: and mercury. So that's a really weird phenomenon to see.
11:48
Speaker 1: Shouldn't they like suck each other into each other pretty quickly?
11:51
Speaker 1: What's the good physics word for that? How do they
11:53
Speaker 1: stay separated if they're both huge and attracting each other
11:56
Speaker 1: and are so close now, suck each other in is
11:58
Speaker 1: exactly they're all right physics word to use, And that's
12:01
Speaker 1: exactly the question people are asking. They're like, hold on
12:04
Speaker 1: a second, how do you get such a big planet
12:06
Speaker 1: so close to the Sun? Can it last very long?
12:09
Speaker 1: Are we seeing something just before it dies? Or can
12:12
Speaker 1: that be a stable configuration? And the models suggests that
12:15
Speaker 1: they can't have been born that close to the Sun
12:17
Speaker 1: and they can't last there very long. And that's the
12:20
Speaker 1: clue that got everybody talking and thinking about whether planets
12:23
Speaker 1: are moving, because they suspect that these hot jupiters form
12:26
Speaker 1: further out and then get sucked in, and so we're
12:29
Speaker 1: witnessing sort of like the end of the life cycle
12:32
Speaker 1: of these planets before they either get torn apart or
12:35
Speaker 1: pulled in. And that's a clue that, like solar systems
12:37
Speaker 1: are volatile, there is stuff going on. It's not just
12:40
Speaker 1: everybody sedately driving in their lane for billions of years?
12:44
Speaker 1: Is Jupiter going to get sucked into our Sun? Not
12:46
Speaker 1: before the Sun explodes? Right? Are you worried about Jupiter?
12:50
Speaker 1: Have you invested in real estate on Jupiter? Well, you know,
12:53
Speaker 1: I was thinking about it. We've been reading about space settlements,
12:55
Speaker 1: but no, obviously not nobody's gonna go live on Jupiter.
12:58
Speaker 1: But maybe it's moons. I went to read I fantastic
13:00
Speaker 1: series and science fiction novels about a civilization in the
13:04
Speaker 1: upper clouds of Jupiter. I think it was called Bio
13:07
Speaker 1: of a Space Tyrant Man. I loved those books when
13:10
Speaker 1: I was a teenager. It was so like fantastically imagined.
13:13
Speaker 1: So I hope that one day humans do get to
13:15
Speaker 1: live on Jupiter, and I hope that we get to
13:17
Speaker 1: keep Jupiter because I like it. I mean, Jupiter is pretty.
13:20
Speaker 1: For all the press that like Mars gets recently, Jupiter
13:22
Speaker 1: is a gorgeous planet. So maybe we should start by
13:25
Speaker 1: thinking about our solar system and understanding of what we
13:28
Speaker 1: know about Jupiter, like where it was made, how it
13:31
Speaker 1: got formed, and that can give us a clue for
13:33
Speaker 1: like why people think there might have been crazy stuff
13:37
Speaker 1: going on in our solar system. At the very beginning
13:39
Speaker 1: of time. Alright, so tell me about how Jupiter got
13:42
Speaker 1: to be where it is. Yes, so we think Jupiter
13:44
Speaker 1: is probably born out in the outer Solar system. There's
13:48
Speaker 1: this point in the Solar system called the ice line,
13:51
Speaker 1: where beyond that it's cold enough for ice to form
13:55
Speaker 1: and to stay melted and basically be like a rock
13:58
Speaker 1: that you can use and building planetary cores. And it's
14:01
Speaker 1: about like three and a half AU. Will remember a
14:04
Speaker 1: U isn't one astronomical units the distance between the Sun
14:08
Speaker 1: and the Earth, So three and a half times the
14:11
Speaker 1: radius of the Earth. Beyond that is the ice line,
14:13
Speaker 1: or some people call it the snow line, and out
14:16
Speaker 1: there it's easier to make big planets because there's ice
14:19
Speaker 1: available to add to your core. So we think that
14:23
Speaker 1: the way the Solar system started obviously, have a big
14:26
Speaker 1: blob of gas and dust and some shock wave comes
14:30
Speaker 1: through it and you get the spark that begins the
14:32
Speaker 1: formation of the whole Solar system, which basically means the Sun.
14:35
Speaker 1: But the Sun has gathered together a huge amount of
14:37
Speaker 1: gas and it has around it a big swirling disk,
14:41
Speaker 1: and that's the disc that's going to provide the material
14:43
Speaker 1: that forms all of the planets now out past the
14:47
Speaker 1: snow line, there's also ice in there. So the ice
14:51
Speaker 1: and the rock and the dust gathered together to make
14:53
Speaker 1: these protoplanetary cores. They start pulling themselves together and that
14:57
Speaker 1: sort of seeds the planets. And so we ended up
15:01
Speaker 1: with what four planets out past the ice line? Is
15:05
Speaker 1: that pretty common? Like that number and like the size
15:08
Speaker 1: of our planets does that match up with what we
15:10
Speaker 1: see in other solar systems. We don't know the answer
15:12
Speaker 1: to that yet, we haven't seen enough. But also remember
15:15
Speaker 1: that we can see a bunch of solar systems, but
15:17
Speaker 1: we're not that great at seeing all of them. And
15:19
Speaker 1: there's certain kinds of solar systems that are easier to see.
15:22
Speaker 1: Like it's easier to see big planets that are closer
15:25
Speaker 1: to their Sun because they block more of the Sun's light.
15:29
Speaker 1: The way we see these exoplanets is that they block
15:32
Speaker 1: the light of their Sun or they tug gravitationally on
15:34
Speaker 1: the Sun. So big planets are easier to see. Close
15:37
Speaker 1: up planets are easier to see, so far out planets
15:40
Speaker 1: harder to spot. Far out small planets harder to spot.
15:44
Speaker 1: Does that mean that like super slow moving things we
15:46
Speaker 1: probably don't have good data on yet because we wouldn't
15:49
Speaker 1: have had a chance to see them pass in front
15:51
Speaker 1: of the sun or tug it as it moves around
15:53
Speaker 1: to the side. That's exactly right, Yeah, we have to
15:56
Speaker 1: watch these things cross their sun, and so basically it's
15:59
Speaker 1: best if you can see and pass a few times
16:01
Speaker 1: so you can see like a regular interval, so the
16:03
Speaker 1: equivalent of several of their years. But if their years
16:06
Speaker 1: take like, you know, a hundred earth years to go around,
16:09
Speaker 1: then we're not going to have had time to see it.
16:11
Speaker 1: So slow moving things, small things, things far from their
16:15
Speaker 1: son are harder to see. So that's a long way
16:17
Speaker 1: of saying we don't have an unbiased picture of what's
16:20
Speaker 1: going on in these other solar systems. And we have
16:22
Speaker 1: to try to play this game of wondering, like, well,
16:25
Speaker 1: if we see only one of them, do we imagine
16:26
Speaker 1: that there are a thousand? Or if we only see
16:29
Speaker 1: two of those, do we imagine there are a hundred.
16:30
Speaker 1: We have to estimate like how good we are seeing them,
16:34
Speaker 1: so we can like invert that and imagine what's actually
16:36
Speaker 1: there that we're missing. But there's a lot that we're missing.
16:38
Speaker 1: Still interesting Yeah, it's really fascinating. And so that's why
16:42
Speaker 1: we focus on our solar system because it's here, it's relevant,
16:45
Speaker 1: and it's one that we can study in great detail.
16:47
Speaker 1: But those other solar systems do give us a lot
16:49
Speaker 1: of clues. Back to jo Butter, we think that it
16:52
Speaker 1: must have had to form and the outer Solar System
16:55
Speaker 1: because that's basically the only place to make these big
16:57
Speaker 1: gas giants. I mean, you need now of ice and
17:01
Speaker 1: enough rock to pull together to make this big core
17:03
Speaker 1: to grab a bunch of gas. Remember, everything in the
17:06
Speaker 1: Solar system is competing with the Sun. In the inner
17:09
Speaker 1: Solar system, is not that much gas left because the
17:12
Speaker 1: Sun has slurped it all up. So to make a
17:13
Speaker 1: gas giant, really have to be far enough away from
17:16
Speaker 1: the Sun to get any of the gas, and you
17:18
Speaker 1: have to be past the snow line, so you can
17:21
Speaker 1: have ice accumulated in your core and get big enough
17:24
Speaker 1: that you can grab some of the gas before all
17:26
Speaker 1: spirals into the Sun. Anyway, Okay, so Jupiter was formed
17:30
Speaker 1: in the outer Solar System and it's still in the
17:33
Speaker 1: outer Solar system. So after the break, let's talk about
17:37
Speaker 1: why we think it moved. Okay, so Jupiter is where
17:54
Speaker 1: we would expect it to be, given how we expect
17:56
Speaker 1: that it formed, So why would we suspect that it
18:00
Speaker 1: had moved at any point. Yeah, it seems at first
18:02
Speaker 1: like it might be a simple story. Right, Jupiter had
18:04
Speaker 1: to form somewhere in the neighborhood where it is today,
18:07
Speaker 1: and so the simplest explanation is, well, maybe it just
18:10
Speaker 1: formed there and stayed there. Why do we imagine it
18:12
Speaker 1: ever took a tour in the inner Solar System? And
18:15
Speaker 1: the reason is that the inner Solar System looks weird,
18:18
Speaker 1: like we can't explain the Inner Solar System in that picture.
18:22
Speaker 1: Our models of how the Solar System came together. We
18:25
Speaker 1: run a bunch of like simulations and try to explain
18:28
Speaker 1: how we got Venus and Earth and Mars. None of
18:31
Speaker 1: the models that we run actually match up with what
18:33
Speaker 1: we see. How are they different? Well, in particular, Mars
18:37
Speaker 1: is really weird, Like Mars is a nice little planet,
18:40
Speaker 1: but it's really small, Like Mars is like ten percent
18:43
Speaker 1: of the mass of the Earth. That's a really small planet.
18:47
Speaker 1: And in all our models of the Solar System, Mars
18:49
Speaker 1: should be a lot bigger, like as you get further
18:52
Speaker 1: out from the Sun, there's more material available because the
18:55
Speaker 1: Sun hasn't stolen at all, and so you expect a
18:58
Speaker 1: planet forming around there to be like about the size
19:00
Speaker 1: of the Earth or even bigger. You know, as you
19:02
Speaker 1: go to the outer Solar System, things get bigger, right,
19:05
Speaker 1: So why is Mars so tiny? Why is it so little?
19:08
Speaker 1: So as you get farther out in the Solar System,
19:10
Speaker 1: things should get bigger. But Jupiter is the biggest and
19:13
Speaker 1: it's not the most far out, So why is Saturn
19:15
Speaker 1: smaller than Jupiter? Then? Oh, yeah, that's a great question.
19:18
Speaker 1: There's a whole other fun story about a sounder Jupiter,
19:20
Speaker 1: maybe switching locations and the whole dance of Uranus and
19:24
Speaker 1: Neptune that they might have done. But you're right, there's
19:26
Speaker 1: a balance there because you want to be far enough
19:28
Speaker 1: away from the Sun so it doesn't steal all the material,
19:31
Speaker 1: but as you get even further away from the Sun
19:33
Speaker 1: you run out of material also, right, Obviously there aren't
19:36
Speaker 1: like super giant planets twice as far away as Jupiter,
19:39
Speaker 1: and so this is something of like a peak location there.
19:42
Speaker 1: Jupiter is probably sitting right there in the spot where
19:44
Speaker 1: you can make the biggest planet. But the question remains
19:46
Speaker 1: like why is Mars so a little what happened to
19:49
Speaker 1: make Mars so tiny? And it's not just Mars? Like
19:52
Speaker 1: the asteroid belt is also kind of weird, like we
19:56
Speaker 1: don't really understand how it formed the way it did. Again,
19:59
Speaker 1: we run these model let's start from just the gas cloud,
20:01
Speaker 1: and you don't get an asteroid belt that looks the
20:03
Speaker 1: way it does. Specifically, our asteroid belt is weird because
20:07
Speaker 1: it has both like rocky objects that seems like they
20:09
Speaker 1: came from the inner Solar System. Plus they have a
20:12
Speaker 1: bunch of icy objects, the kinds of things you would
20:15
Speaker 1: find like in the Kuiper Belt or deeper further out
20:18
Speaker 1: in the Solar system. So there're these like pieces of
20:20
Speaker 1: evidence you were talking earlier about like how could we
20:23
Speaker 1: possibly find clues about things that happened so long ago?
20:26
Speaker 1: Like these are the things that have puzzled scientists for
20:28
Speaker 1: a long time. So is the asteroid belt inside the
20:32
Speaker 1: ice line or on the Jupiter side of the ice line? Yeah,
20:35
Speaker 1: the asteroid belt is really weird. Actually part of his
20:38
Speaker 1: inside the ice line, the part that's like closer to Mars,
20:41
Speaker 1: remember it sits between Mars and Jupiter. But it also
20:44
Speaker 1: extends kind of far out, and part of it actually
20:47
Speaker 1: is in orbit with Jupiter. Like it's not all between
20:50
Speaker 1: Mars and Jupiter. There's these big blobs of asteroids that
20:53
Speaker 1: are in Jupiter's orbit just sort of like rotated away
20:57
Speaker 1: from them, like you know, thirty degrees around the thirty
20:59
Speaker 1: degrees the other direction, and stuff is sort of like
21:02
Speaker 1: sloshing back and forth. So some of it's definitely out
21:04
Speaker 1: there past the ice line and can stay frozen, and
21:07
Speaker 1: some of it's a little bit closer. Interest. Yeah, and
21:11
Speaker 1: so we have these mysteries, and I love that. This
21:14
Speaker 1: is like the way we do science. You know, we say, well,
21:16
Speaker 1: we think we understand how the solar system works, but
21:19
Speaker 1: let's double check. Let's run a bunch of models and
21:22
Speaker 1: see if what we get matches up with what we
21:26
Speaker 1: actually expected. And when you see those weird deviations, when
21:29
Speaker 1: you see something that doesn't make sense, that's when you
21:32
Speaker 1: know you might have found something. So it's like when
21:34
Speaker 1: your model doesn't work is a potential discovery moment. It
21:38
Speaker 1: isn't that how we figured out how humans figured out
21:41
Speaker 1: that was it? Neptune was out there, something was not
21:43
Speaker 1: working mathematically, so there had to be another planet out
21:45
Speaker 1: there exactly. Yeah, there's all these times when something hasn't
21:49
Speaker 1: quite worked, just like you're saying, the orbits of the
21:51
Speaker 1: planets don't quite make sense, and that's been a clue.
21:54
Speaker 1: Is to like a huge discovery, but always makes me
21:56
Speaker 1: think about like all the other times when your model
21:59
Speaker 1: doesn't work and it just because like you have a
22:01
Speaker 1: bug where you did something stupid, you know, and you
22:04
Speaker 1: can't be like, oh my gosh, maybe I've discovered something fantastic.
22:07
Speaker 1: Sort of frustrating part of science. Yeah, usually for me,
22:10
Speaker 1: it's just a bug, but I'll keep all me out hope.
22:14
Speaker 1: We have that experience all the time. It's a large
22:16
Speaker 1: hage on collider because we're always on the lookout for
22:18
Speaker 1: something unexplained, something new, something weird, some new particle that
22:22
Speaker 1: we've just created, or mini black hole or something, and
22:25
Speaker 1: it might be evidenced by some deviation in the data
22:28
Speaker 1: compared to what we expect. But we see that all
22:31
Speaker 1: the time, especially young students make mistakes and they see
22:34
Speaker 1: something weird, like oh my gosh, did I discover something
22:37
Speaker 1: like yeah, well, you discovered that you don't know how
22:39
Speaker 1: to run this program correctly. You discovered that you're missing
22:42
Speaker 1: a bracket. But yeah, exactly, you discovered that bugs are
22:46
Speaker 1: easy to insert in programs, but you also you don't
22:49
Speaker 1: want to squash their enthusiasm. Right, It's wonderful to see
22:51
Speaker 1: this in young scientists, to imagine that they could be
22:54
Speaker 1: the ones making some discovering this could be a historic moment.
22:57
Speaker 1: So I like to tell them stories like this, because
22:59
Speaker 1: it does act really happens sometimes, Right, Sometimes we run
23:02
Speaker 1: these models and we see something weird and it means
23:04
Speaker 1: something real about the universe. Awesome. We can all keep
23:07
Speaker 1: our fingers across the will have those amazing moments where
23:11
Speaker 1: it's not you not being smart enough, it's actually the
23:13
Speaker 1: universe revealing herself to you. And so we're trying to understand,
23:16
Speaker 1: like how our solar system got to be weird the
23:19
Speaker 1: way it is. Why don't we have a bunch of
23:20
Speaker 1: other planets close to the star? Why is mar so small?
23:25
Speaker 1: Why is the asteroid belt the way it is? This
23:27
Speaker 1: weird mix of rocky and icy objects. So we've taken
23:31
Speaker 1: clues from these other solar systems that have big planets
23:34
Speaker 1: really close to their stars. One idea initially was like
23:37
Speaker 1: maybe Jupiters formed close to the Sun. And then like
23:40
Speaker 1: drifted out and along the way sort of messed up
23:43
Speaker 1: things in the Solar system. But you just told us
23:46
Speaker 1: that it needed to be out there where there's ice
23:48
Speaker 1: in order to form. Could it have possibly formed near
23:51
Speaker 1: the Earth? So people spend a while trying to cook
23:53
Speaker 1: up these models and wondering like maybe there's a way
23:56
Speaker 1: to have a hot jupiter that survives, or maybe there's
23:59
Speaker 1: a way to form a planet really close to the star.
24:02
Speaker 1: Maybe there are other methods. So you know, this idea
24:05
Speaker 1: of how you form a jupiter is sort of one model,
24:08
Speaker 1: but there are other models. There's like, you know, gravitational
24:10
Speaker 1: instabilities that maybe stuff smashed together to make like an
24:13
Speaker 1: unusually large object, which then like gathered together a bunch
24:16
Speaker 1: of stuff. And people have been working on these things
24:18
Speaker 1: and trying to put them together, and you know, this
24:20
Speaker 1: is the kind of creativity that's inspired by basically a mystery.
24:24
Speaker 1: But it doesn't seem to really be working, Like there's
24:26
Speaker 1: just not enough gas and not enough mass close to
24:30
Speaker 1: the star, and also it's just too warm, Like a
24:33
Speaker 1: lot of this stuff, if you did happen to form
24:35
Speaker 1: a big object, would get blown apart by the sun.
24:39
Speaker 1: The Sun just like boil the gas off of that planet.
24:42
Speaker 1: And it also probably just like holding apart by the
24:45
Speaker 1: tidal forces. Remember that the Sun has a lot of
24:47
Speaker 1: gravity and it tugs on everything. But if you're a
24:50
Speaker 1: really big object, it's going to tug on the part
24:53
Speaker 1: of you that's closer to the star more than it
24:55
Speaker 1: tugs on the part of you that's far from the star.
24:57
Speaker 1: And that's effectively the same thing as trying to pull
25:00
Speaker 1: you apart. And that's why, for example, you get close
25:03
Speaker 1: to a black hole, you won't survive, because you'll get
25:06
Speaker 1: pulled apart by the relative difference in the gravity at
25:09
Speaker 1: your feet and at your head. It's called spaghettification, one
25:13
Speaker 1: of the best physics words out there. And so now
25:16
Speaker 1: imagine like making a big gas giant. You've accomplished the impossible.
25:20
Speaker 1: You've formed a gas giant close to your star. What's
25:22
Speaker 1: going to happen The star pretty quickly is going to
25:25
Speaker 1: spaghettify Jupiter. And like, that's a lot of spaghetti. I'm
25:29
Speaker 1: there for that. I love spaghetti. So are people still
25:32
Speaker 1: work on that question or have scientists pretty much decided like, okay,
25:36
Speaker 1: this is not the answer. There's always somebody is still
25:38
Speaker 1: working on that question. Right. There are people out there
25:41
Speaker 1: who think that it might have been possible to make
25:43
Speaker 1: a Jupiter close to the star, and they're working on
25:45
Speaker 1: their models, and in that line of thinking, they're hoping
25:48
Speaker 1: that you've made this jupiter close to the star and
25:51
Speaker 1: that it's somehow we don't know how, then drifted out
25:54
Speaker 1: to the outer Solar System and in doing so has
25:58
Speaker 1: perturbed the asteroid belt and in doing so has like
26:01
Speaker 1: stolen a lot of the material that might have made Mars.
26:04
Speaker 1: But I don't think that it's a mainstream idea. I mean,
26:06
Speaker 1: there's always somebody out there, you know, smoking a banana,
26:09
Speaker 1: appeals and thinking about it. And I encourage that, and
26:11
Speaker 1: that kind of creativity is wonderful, and you know, diversity
26:14
Speaker 1: of ideas is also very very important for the scientific method.
26:18
Speaker 1: But I don't think the leading idea is that you
26:21
Speaker 1: form a hot jupiter close to the Sun and that
26:24
Speaker 1: it then drifts out into the outer Solar system. Okay,
26:27
Speaker 1: so it started in the outer Solar System and then
26:31
Speaker 1: it went on a cool vacation towards the Sun and
26:33
Speaker 1: decided it preferred skiing. Yeah, And so we don't think
26:38
Speaker 1: that this idea of it's starting an inner solar system
26:41
Speaker 1: and moving out makes much sense. And another clue is
26:45
Speaker 1: that when we look at these other solar systems, the
26:48
Speaker 1: ones that have hot jupiters, and we wonder, like, how
26:50
Speaker 1: are they made and how could that survive? There's some
26:53
Speaker 1: evidence that we're looking at our really young solar systems,
26:56
Speaker 1: solo systems that haven't been around for very long. And
26:59
Speaker 1: so one explanation for how hot jupiters even exist is
27:03
Speaker 1: that they're transient, that they're gonna be absorbed by the
27:06
Speaker 1: star that we're seeing them before they get spaghettified and
27:09
Speaker 1: sucked in and basically just become part of the star.
27:12
Speaker 1: Because we don't tend to see hot jupiters in older
27:15
Speaker 1: solar systems. Ah, so it started in the outer solar system,
27:19
Speaker 1: it got sucked in, and we are seeing it at
27:21
Speaker 1: a point where it is sort of in the process
27:23
Speaker 1: of soon to be absorbed by the sun. Is that right?
27:26
Speaker 1: That's the leading explanation for why we are seeing hot
27:29
Speaker 1: jupiters in other solar systems. But you know, of course
27:32
Speaker 1: that doesn't answer the question of our solar system because
27:35
Speaker 1: we don't have a hot Jupiter, right, But we still
27:37
Speaker 1: have to explain what happened in the inner Solar System.
27:40
Speaker 1: So we have Jupiter starting in the outer Solar System,
27:43
Speaker 1: we think that makes more sense. We don't have it
27:46
Speaker 1: currently in the Inner Solar System. So then there's this
27:48
Speaker 1: question of like, well, how could it have perturbed things
27:51
Speaker 1: in the inner Solar System? You know, it's sort of
27:53
Speaker 1: like got an alibi. It's like I was born here
27:55
Speaker 1: and I'm still here. Why are you looking at me? Right? Okay,
27:58
Speaker 1: So the progress we've made so far are is that
28:01
Speaker 1: there's an explanation that we don't think is right. So
28:04
Speaker 1: let's try another explanation and see if we can maybe
28:08
Speaker 1: solve some of the problems with what's happening with Mars
28:10
Speaker 1: and the asteroid belt after we take a break. Okay,
28:25
Speaker 1: So we feel pretty confident that Jupiter started in the
28:28
Speaker 1: outer Solar System and it didn't start in the Inner
28:30
Speaker 1: Solar System and then move out. So if it started
28:33
Speaker 1: in the outer Solar System and it's still there, now,
28:36
Speaker 1: does that mean at some point Jupiter sort of toyed
28:39
Speaker 1: with the idea of a summer vacation and then decided
28:42
Speaker 1: it preferred the cold and went back to go skiing.
28:44
Speaker 1: Did it come to the Sun and then leave. I know,
28:47
Speaker 1: this is that moment in the Murder mystery where you're like,
28:50
Speaker 1: this person was home all evening. Hold on a second
28:53
Speaker 1: to actually have a way to account for all their whereabouts.
28:56
Speaker 1: Could they have snuck out and committed the murder and
28:58
Speaker 1: then come back in time? How fast are those trains?
29:02
Speaker 1: We can't leave Jupiter in the outer Solar System for
29:04
Speaker 1: its whole history. But now we have a crazier idea,
29:07
Speaker 1: which is maybe Jupiter did trend into the inner Solar
29:11
Speaker 1: System just like all those other hot jupiters were seeing
29:14
Speaker 1: in other solar systems, but that it stopped and it
29:18
Speaker 1: turned around and it went back out to the outer
29:21
Speaker 1: Solar system. So this is called the Grand Tach hypothesis.
29:25
Speaker 1: Seeing Jupiter's like a sailboat that like sailed into the
29:29
Speaker 1: inner Solar System and then sailed back out. This is
29:31
Speaker 1: blowing my mind. So let's break it into two parts.
29:34
Speaker 1: I guess, So, how did it get pulled in? Just
29:36
Speaker 1: through the typical gravity pulled it in? Yeah, so you
29:39
Speaker 1: have to cast your mind back to the very very
29:41
Speaker 1: early days of the Solar system. Solar system we think
29:44
Speaker 1: is about four or five billion years old and we're
29:47
Speaker 1: talking about things that happened in the first few million years.
29:50
Speaker 1: You shouldn't be imagining a bunch of planets around the star.
29:53
Speaker 1: You should be imagining a star and then a huge
29:56
Speaker 1: disc of gas and dust, and then inside that gas
29:59
Speaker 1: and dusk, we're forming planets. But they're not like clear,
30:02
Speaker 1: they're not like totally separated. If you were doing astronomy
30:05
Speaker 1: back then, you would have a really hard time seeing
30:07
Speaker 1: any planets because there's so much gas and dust everywhere.
30:10
Speaker 1: So the beginning of the story in the first few
30:12
Speaker 1: million years is that, like proto Jupiter has formed, but
30:16
Speaker 1: it's not as far out as it is now. It's
30:18
Speaker 1: only like three and a half au like right there
30:21
Speaker 1: on the snow line. As we were saying earlier, like
30:23
Speaker 1: the peak place to make a gas giant is just
30:26
Speaker 1: pass where things freeze, so you can gather ice and
30:28
Speaker 1: rocks and dust, but not so far out that things
30:31
Speaker 1: are getting dilute. So Jubiter forms there and then it
30:35
Speaker 1: drifts into the inner Solar system. As you're asking, like
30:38
Speaker 1: what makes that happen, it's it just the Sun's gravity,
30:41
Speaker 1: and you know anything can orbit stable. The Sun obviously
30:45
Speaker 1: has a lot of gravity, but The reason, like the
30:47
Speaker 1: Earth is not falling into the Sun right now is
30:50
Speaker 1: that we have a lot of speed. We're in a
30:51
Speaker 1: stable orbit. So we think Jupiter probably wasn't a stable orbit.
30:55
Speaker 1: But remember it wasn't on its own. It's still surrounded
30:58
Speaker 1: by a lot of gas and us that hasn't gotten
31:01
Speaker 1: pulled into any planet. So the idea is that it
31:04
Speaker 1: interacted with that gas and dust, which basically slowed it
31:06
Speaker 1: down and started falling in towards the Sun. That must
31:10
Speaker 1: have been very scary for Jupiter. I know, it's like
31:14
Speaker 1: this inextricable fall, right, you know that you're like rolling
31:17
Speaker 1: in towards this huge burning ball of plasma and there's
31:20
Speaker 1: basically nothing you can do about it. So very dramatic moment.
31:24
Speaker 1: And these gases eventually, you know, spiraled in and they
31:27
Speaker 1: fell into the Sun, and Jupiter was spiraling and also
31:30
Speaker 1: and so the idea is that it passed through the
31:33
Speaker 1: inner Solar System and along the way it gobbled up
31:37
Speaker 1: a lot of material which eventually would have otherwise led
31:41
Speaker 1: to a larger Mars. How far in did it go?
31:44
Speaker 1: Did it get like Earth close or just Mars close,
31:47
Speaker 1: not quite Earth close. We think that it came into
31:50
Speaker 1: like about one and a half a you. And that's
31:53
Speaker 1: why we still have Earth as a pretty reasonable size,
31:56
Speaker 1: because Jupiter came in and it either like gobbled up
31:58
Speaker 1: the material to make ours or scattered it and threw
32:02
Speaker 1: it into the sun. But these things in the inner
32:04
Speaker 1: Solar system were a bit more protected. Okay, so part
32:07
Speaker 1: of Jupiter should have been in Mars. It's like those twins,
32:09
Speaker 1: you know, where like one of them eat the other
32:11
Speaker 1: one and you still have like a jaw or whatever
32:13
Speaker 1: inside the body of the adult. Those are the craziest stories.
32:16
Speaker 1: I don't think they're actually eating the other one, but yes,
32:19
Speaker 1: I know where you're going with that. Well, you don't
32:21
Speaker 1: believe in the evil twin theory that twins can eat
32:23
Speaker 1: each other in the roomb. I was reading about this
32:25
Speaker 1: the other day, and I think it's they like absorb
32:28
Speaker 1: eating suggests a bit more intention that I think is
32:32
Speaker 1: actually happening in there. You know, I'm going to use
32:34
Speaker 1: that next time I eat my kids cookies. I'm like,
32:36
Speaker 1: I didn't eat your cookies, I just absorbed them. And
32:39
Speaker 1: Kelly the biologist, she tells me that's different. And then
32:43
Speaker 1: your children remind you that you are not a fetus.
32:46
Speaker 1: You're a grown man. You can make decisions, and so
32:49
Speaker 1: you know, let them know that they can call me
32:50
Speaker 1: if they need back up. All right, I'll give them
32:53
Speaker 1: your number. Anyways, So Jupiter's out there like unintentionally absorbing
32:57
Speaker 1: the materials that Mars would have needed to get larger
33:00
Speaker 1: and scattering a bunch of other stuff, and so it
33:03
Speaker 1: came into about one and a half a U. And
33:06
Speaker 1: that actually explains a lot about what's going on in
33:09
Speaker 1: our inner Solar system. That's why there are no like
33:11
Speaker 1: other rocky planets after Mars. We think there might have
33:14
Speaker 1: also been other planets out there that were forming that
33:17
Speaker 1: Jupiter just like nudged into the Sun. So why did
33:20
Speaker 1: it nudge them into the Sun as opposed to pulling
33:22
Speaker 1: it into Jupiter. Yeah, we don't know. It could have
33:25
Speaker 1: been either fate, right, this is very chaotic, and so
33:27
Speaker 1: it depends exactly on how big they were and how
33:30
Speaker 1: they were aligned, and so the fate of these planets
33:32
Speaker 1: could be like fall into the Sun or get absorbed
33:35
Speaker 1: by Jupiter, or even get tossed out of the Solar
33:38
Speaker 1: system entirely. Like Jupiter is a big bully, right, It's
33:41
Speaker 1: so much bigger than Earth and Mars, and it comes
33:44
Speaker 1: in and it doesn't take very much to really disrupt
33:47
Speaker 1: the inner Solar System. Okay, so how does this describe
33:51
Speaker 1: what happened or does this help explain what happened with
33:54
Speaker 1: the asteroid belt. Yeah, so it actually all really fits
33:57
Speaker 1: together beautifully, because to explain the after oid belt, you
34:01
Speaker 1: need Jupiter to get back out to where it was. Right.
34:04
Speaker 1: The asteroid belt has rocky stuff in it from the
34:07
Speaker 1: inner Solar System, but also I see stuff from the
34:10
Speaker 1: outer Solar System, and so if you could somehow turn
34:13
Speaker 1: Jupiter around, right, we've seen all these other solar systems.
34:17
Speaker 1: Also that these big gas giants sometimes fall slowly in
34:20
Speaker 1: towards the star, and we think that in most cases
34:23
Speaker 1: probably they just end up inside the star. They didn't
34:26
Speaker 1: happen in our case. So we need Jupiter move somehow
34:28
Speaker 1: to the outer Solar System, and in doing so we
34:31
Speaker 1: think that it will have disrupted the asteroid belt and
34:34
Speaker 1: also disrupted the Kuiper Belt, like pulled some of those
34:37
Speaker 1: objects towards the inner Solar System, so that the asteroid
34:40
Speaker 1: belt then has like a weird mixture of these like
34:43
Speaker 1: further out objects and these inner objects. And that's why
34:47
Speaker 1: we see these like icy objects and rocky objects in
34:50
Speaker 1: our asteroid belt. If we can get Jupiter to go
34:52
Speaker 1: in and then come back out, that's fascinating. So now,
34:56
Speaker 1: how you told us that Jupiter probably slowed down own
35:00
Speaker 1: and that's what caused it to get pulled in. So
35:03
Speaker 1: for Jupiter to go back out again, what is required
35:07
Speaker 1: for that? Doesn't have to start speeding up and then
35:09
Speaker 1: also kind of get nudged. Why did it leave? Well, Jupiter,
35:13
Speaker 1: we think probably was saved by its friend Saturn, because
35:17
Speaker 1: Saturn has the same fate, right, Saturn, also a big
35:19
Speaker 1: gas giant, also probably surrounded by big swarming clouds of gas,
35:24
Speaker 1: getting slowed down drifting in towards the Inner Solar System.
35:28
Speaker 1: To imagine Jupiter like the big brother and then Saturn
35:31
Speaker 1: like the younger sister or the younger brother, following in
35:33
Speaker 1: behind it, having sort of the same fate and seeing
35:36
Speaker 1: what's happening to Jupiter. But the calculations suggests that it's
35:39
Speaker 1: possible that as these two things get close to the
35:42
Speaker 1: Inner Solar System that they then start tugging on each other,
35:45
Speaker 1: and that their gravitational interaction makes this weird resonance where
35:49
Speaker 1: they're pushing on each other and they're passing around the Sun.
35:52
Speaker 1: They're tugging on each other in the same way. So
35:54
Speaker 1: they do this like weird dance. Like imagine two people
35:57
Speaker 1: spinning and both letting go and they flown out of
36:01
Speaker 1: the inner Solar System. I know, it's crazy. It's like
36:03
Speaker 1: Saturn like dove in after Jupiter and saved them both. Right,
36:07
Speaker 1: they could have ended very badly. Yeah, there's got to
36:09
Speaker 1: be a buddy comedy that could be written about this
36:11
Speaker 1: or something that's wild exactly. And so that's maybe the
36:16
Speaker 1: story that Jupiter started in the outer Solar system, got
36:20
Speaker 1: tugged in as it's got slowed down by all this gas,
36:23
Speaker 1: and then got saved by Saturn. And that would explain
36:26
Speaker 1: why Mars is so small, and it would explain why
36:29
Speaker 1: the asteroid belt has the weird composition that it does have.
36:33
Speaker 1: And so is that the only explanation we have for
36:35
Speaker 1: how Jupiter got thrown back out again? Or is that
36:38
Speaker 1: just the top explanation right now? That's the top explanation.
36:42
Speaker 1: And we don't think that it's very likely. I mean
36:44
Speaker 1: we think that in most cases, when you have a
36:46
Speaker 1: big gas giant that falls towards your star, it ends
36:50
Speaker 1: in the way you would expect that it falls towards
36:52
Speaker 1: the star and gets gobbled up, And so most solar
36:55
Speaker 1: systems that have basically a Jupiter, we think that it
36:58
Speaker 1: doesn't last for very long. So that means our solar
37:00
Speaker 1: system is probably weird, right, that we're unusual for keeping
37:05
Speaker 1: this big gas giant and having it back in the
37:07
Speaker 1: outer Solar system in a stable way after all the
37:10
Speaker 1: gas and dust have cleared out. Now Jupiter can go
37:13
Speaker 1: back out to the past the ice line and hang
37:15
Speaker 1: out for billions of years. That would suggest that the
37:17
Speaker 1: reason we're weird is because we also have a Saturn.
37:20
Speaker 1: So do other solar systems without hot jupiters also have
37:24
Speaker 1: a Saturn equivalent? Yeah, great question. I don't think we
37:27
Speaker 1: know the answer to that, because these planets are much
37:30
Speaker 1: harder to spot, right, We're talking about things five six
37:33
Speaker 1: seven a U that only passed their son every few years. Right, Like,
37:38
Speaker 1: if you were observing our Solar system from really far away,
37:41
Speaker 1: Jupiter and Sounder would not be that easy to spot
37:44
Speaker 1: because while they're pretty big, they're also really far away
37:47
Speaker 1: from the Sun and it takes them years and years
37:49
Speaker 1: to orbit, so you would have to be watching our
37:52
Speaker 1: solar system for a long time with a really good
37:55
Speaker 1: telescope before you discovered Jupiter and Saturn. So that's not
37:58
Speaker 1: something that we're really sort of good at knowing about
38:00
Speaker 1: other solar systems. Yet so far, we mostly know what's
38:03
Speaker 1: going on in the inner Solar system for big, fast
38:06
Speaker 1: moving planets around their star. So astronomers have like incredible
38:10
Speaker 1: job security because we're gonna need to watch for hundreds
38:12
Speaker 1: of years to get these data and tuarly the government's
38:15
Speaker 1: going to pay for all of it, exactly. Yeah, And
38:18
Speaker 1: it's incredible what we have learned so far. You know,
38:20
Speaker 1: we've learned so much about how our solar system is
38:23
Speaker 1: weird to compare to the other solar systems that's out there,
38:26
Speaker 1: and that's sort of like cool, like, hey, our solar
38:29
Speaker 1: system is awesome and special. It's also a little bit
38:32
Speaker 1: disheartening because if you believe in aliens, or you want
38:35
Speaker 1: to believe in aliens, and you want to think that
38:37
Speaker 1: there are lots of opportunities for life out there, it
38:40
Speaker 1: makes the story a little bit harder because to have
38:43
Speaker 1: a solar system like ours and a planet like ours,
38:46
Speaker 1: you need this sort of special thing to happen, this
38:49
Speaker 1: dance of the two gas giants to clear out the
38:52
Speaker 1: inner Solar System and then also save themselves and being
38:56
Speaker 1: the outer Solar system. You know, we think that Jupiter
38:59
Speaker 1: probably protect the Earth from a lot of sort of
39:01
Speaker 1: incoming bombardment because it's so big. It's like hoovering up
39:04
Speaker 1: all the comets and other stuff. So it's a special
39:07
Speaker 1: configuration we have. You've kind of bummed me out. You know.
39:11
Speaker 1: At the beginning of this conversation, when we were talking
39:13
Speaker 1: about how big our data set is, I was thinking,
39:16
Speaker 1: all right, that's got to be good for the Drake equation.
39:18
Speaker 1: You know, we're like adding all of these possible solar
39:21
Speaker 1: systems that might have earthlike planets. But now what you're
39:24
Speaker 1: telling me is probably a lot of the ones that
39:26
Speaker 1: are out there don't have earthlike planets. And now I'm
39:30
Speaker 1: kind of bummed, yeah, a little bit. And we've been
39:32
Speaker 1: excited to find what we thought were earthlike planets in
39:35
Speaker 1: these other solar systems, ones about the right radius, about
39:38
Speaker 1: the right distance from the star. But what we don't
39:40
Speaker 1: know is if they really have the right composition to
39:43
Speaker 1: be an Earth. You know, it might be that Jupiter
39:46
Speaker 1: came through the Inner Solar System and it cleared out
39:48
Speaker 1: a lot of gas, etcetera, etcetera, And so we ended
39:51
Speaker 1: up with a planet just the right combination of stuff
39:54
Speaker 1: to have life. If Jupiter hadn't come through the Inner
39:57
Speaker 1: Solar System, Earth might have been a little bit bigger
39:59
Speaker 1: and then might have been more gas, So we might
40:01
Speaker 1: have ended up with a very different composition. You can
40:03
Speaker 1: imagine like a super Earth that's like choked in hydrogen
40:07
Speaker 1: instead of having the atmosphere that we have you other way,
40:10
Speaker 1: like Venus is just like choked in CEO two. It's
40:13
Speaker 1: very oppressive. And so it might be a lot of
40:16
Speaker 1: the planets we're seeing in these other Solar systems are
40:19
Speaker 1: not actually sort of habitable in the way that we
40:22
Speaker 1: would hope for. They're not really copies of Earth. They
40:25
Speaker 1: might have the right size roughly and being roughly the
40:28
Speaker 1: right position, but that doesn't mean to have the same
40:30
Speaker 1: conditions as Earth. Man, we're lucky. Oh we're special. We're special.
40:36
Speaker 1: I'm gonna go with lucky. But maybe life is better
40:39
Speaker 1: if you go with special. So did Jupiter go like
40:42
Speaker 1: back to where it came from or did it end
40:44
Speaker 1: up a little closer a little farther out than where
40:46
Speaker 1: it was before. It ended up a little farther out.
40:48
Speaker 1: It like it wanted to go out. In the excerpts,
40:50
Speaker 1: you know, it was born in the suburbs, and it
40:52
Speaker 1: came to the inner city, and then it decided in
40:54
Speaker 1: its retirement it wanted to live further out. So it
40:57
Speaker 1: started out at three and a half a U. Came
40:59
Speaker 1: in and probably about one and a half and now
41:02
Speaker 1: it's comfortably out around five point two a U. I
41:05
Speaker 1: can totally understand how Jupiter feels. I was born in
41:07
Speaker 1: the suburbs and then I moved to a big city
41:10
Speaker 1: and now I live out in the country where nobody
41:12
Speaker 1: else is. So I feel your Jupiter. Well, it thanks
41:16
Speaker 1: a lot to feel Jupiter. And the story doesn't end there.
41:19
Speaker 1: What we talked about is like the first few million
41:21
Speaker 1: years of the Solar System. But there's still a lot
41:24
Speaker 1: of interesting planetary dynamics that need to be explained. Like
41:28
Speaker 1: we think that maybe Uranus and Neptune switched places at
41:32
Speaker 1: some point, and that Jupiter and Saturn may not have
41:35
Speaker 1: sort of ended up where they are now, that it
41:37
Speaker 1: may have taken a little while, and they may have
41:39
Speaker 1: also done some later migrations we're talking like five hundred
41:42
Speaker 1: million years after the start of the Solar system, So
41:46
Speaker 1: we like to think about the Solar system is sort
41:47
Speaker 1: of like it is what it is, and it's been
41:49
Speaker 1: what it's been. But if you did it like in
41:52
Speaker 1: time lapse over like hundreds of millions of years, it
41:54
Speaker 1: would seem pretty chaotic. It would seem like, wow, there's
41:57
Speaker 1: really something happening there. So that this idea of Jupiter
42:00
Speaker 1: moving in and out, is this like totally accepted by
42:05
Speaker 1: the mainstream or is this just sort of a theory
42:09
Speaker 1: that some people ascribe to. How broadly is this idea accepted? Yeah,
42:13
Speaker 1: it's somewhere in between. The astronomers I spoke to think
42:16
Speaker 1: it's like probably the most plausible explanation. But you know,
42:20
Speaker 1: there's a lot of details still to get right, and
42:22
Speaker 1: our models are just going to keep getting better and better,
42:25
Speaker 1: and then we could ask more and more detailed questions.
42:27
Speaker 1: And right now the models explain Mars, but as we
42:30
Speaker 1: make those models better, we can ask more specific questions
42:32
Speaker 1: about like why does Mars have the composition that it
42:35
Speaker 1: does and why does it get exactly this small and
42:38
Speaker 1: not larger? And maybe as we do those studies we'll
42:41
Speaker 1: find discrepancies and things that don't work, and then we'll
42:44
Speaker 1: need to modify this model. Or maybe there's some other
42:47
Speaker 1: crazy part of this story that we haven't even thought
42:50
Speaker 1: of yet that could be revealed by some little detail
42:53
Speaker 1: that some student uncovers. So, given the gaps in our
42:56
Speaker 1: data sets, which are caused by things that are hard
42:59
Speaker 1: to remove, like really really slow moving planets, what do
43:02
Speaker 1: you think the chance is that by the time you
43:05
Speaker 1: and I are, you know, retiring, that will be able
43:09
Speaker 1: to say, like, definitely, that's what Jupiter. You know, maybe
43:12
Speaker 1: we'll never be able to say definitely, but we feel
43:14
Speaker 1: super confident that that's what Jupiter did. Is this a
43:17
Speaker 1: problem that could get solved soon or are we looking
43:19
Speaker 1: at decades and decades before we can really get a
43:21
Speaker 1: good answer. Well, that depends, Kelly, how long until you
43:24
Speaker 1: plan to retire. I'm not sure I'm ever going to retire.
43:27
Speaker 1: But you know, the the average age of a woman
43:29
Speaker 1: in the US when they die is what seven seventy
43:32
Speaker 1: seven something like that, So that time scale, I think
43:35
Speaker 1: that our understanding of our solar system and other solar
43:38
Speaker 1: systems is going to be continually revolutionized, basically every ten
43:42
Speaker 1: years for the next hundred years, because we are just
43:46
Speaker 1: at the very beginning of understanding how these things work,
43:49
Speaker 1: because we have just started to look and to see
43:52
Speaker 1: these other planets, and we're going to find lots more
43:54
Speaker 1: surprises once we developed telescopes that are better at these things.
43:58
Speaker 1: Was James web launches and t to us more about
44:01
Speaker 1: cold planets. James Webb's an infrared telescope that can see
44:05
Speaker 1: things that are not just quite as hot, that can
44:07
Speaker 1: see like cold disks of protoplanetary formation and actually maybe
44:11
Speaker 1: individual planets that glow in the infrared. So we have
44:15
Speaker 1: a lot more information coming, and if the universe holds
44:18
Speaker 1: true to its reputation, it will be filled with surprises
44:22
Speaker 1: that upend our ideas. So probably by the time we retire,
44:26
Speaker 1: people will look back at these ideas as quaint and goofy,
44:29
Speaker 1: and then we'll have a much more interesting idea, probably
44:31
Speaker 1: filled with dramatic events we haven't even considered. You know,
44:35
Speaker 1: it's a really fascinating time to be alive with the
44:38
Speaker 1: kind of data that we're able to collect right now,
44:40
Speaker 1: It really is. It's a kind of time that makes
44:41
Speaker 1: me just want to like live another ten years because
44:44
Speaker 1: the things we're learning are just blowing our minds. You know.
44:47
Speaker 1: It makes me wonder, like, what would a children's book
44:50
Speaker 1: about the Solar system say in a hundred years, right, Like,
44:54
Speaker 1: I would love, I would kill to travel forward in
44:56
Speaker 1: time and steal children's books about science. Well, this suggests
45:01
Speaker 1: that biology needs more funding because we need people to
45:04
Speaker 1: be working on the problem of immortality. Don't give me that.
45:07
Speaker 1: On my campus, we have like ten times as many
45:09
Speaker 1: biologists as businists already. Alright, alright, fair enough, but I
45:13
Speaker 1: love biologists literally, I mean, I'm married to one. So
45:16
Speaker 1: I'm definitely pro biology. More funding for all the sciences
45:19
Speaker 1: so we can unravel these amazing mysteries of the universe.
45:22
Speaker 1: There you go, agreed. Alright, something we can agree on.
45:26
Speaker 1: So thank you everybody for joining us on this tour
45:29
Speaker 1: of the early days of our solar system, the dramatic
45:32
Speaker 1: story of Jupiter's visit to the inner Solar System and
45:35
Speaker 1: how it might explain everything that we're seeing, all the
45:38
Speaker 1: mysteries about the size of Mars and the composition of
45:40
Speaker 1: the asteroid belt. Thank you very much for sharing your
45:43
Speaker 1: curiosity with us. And thank you again to Kelly, our
45:46
Speaker 1: wonderful guest host for joining us on today's episode, Thanks
45:49
Speaker 1: for having me on the show, and thanks for listening everyone.
45:51
Speaker 1: It was a lot of fun, alright, tune in next time. Yeah,
46:01
Speaker 1: thanks for listening, and remember that Daniel and Jorge Explain
46:04
Speaker 1: the Universe is a production of I Heart Radio. Or
46:07
Speaker 1: more podcast from my heart Radio, visit the I heart
46:10
Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your
46:13
Speaker 1: favorite shows. H