WEBVTT - Did Jupiter once have a different orbit? 0:00:08.640 --> 0:00:13.080 Hey, Kelly, how do you feel about moving? It always 0:00:13.119 --> 0:00:15.280 seems like it's going to be exciting, but it's always 0:00:15.280 --> 0:00:19.119 a drag. No. Right, It's like there's always one more 0:00:19.280 --> 0:00:23.040 box of stuff, and by mathematical induction, that means we 0:00:23.079 --> 0:00:26.480 all have infinite totally checks out. I mean I have 0:00:26.600 --> 0:00:30.040 like infinite back pain from my last move. Sometimes I 0:00:30.040 --> 0:00:32.040 wish I had a mobile home so that I wouldn't 0:00:32.080 --> 0:00:34.239 have to pack everything up every time. That is a 0:00:34.280 --> 0:00:37.240 genius solution. I mean, you move more stuff, but you 0:00:37.400 --> 0:00:39.800 do less work because you take your whole house with 0:00:39.840 --> 0:00:43.839 you exactly. I wonder if it's scales. I'm thinking like 0:00:44.120 --> 0:00:49.080 mobile neighborhoods, mobile cities, maybe like mobile planets. Earth is 0:00:49.120 --> 0:00:52.800 just one big mobile home. Man, I didn't realize we 0:00:52.840 --> 0:01:11.600 lived in a cosmic trailer park. I'm Daniel, I'm a 0:01:11.640 --> 0:01:16.039 particle physicist, and I once moved across the Atlantic eleven 0:01:16.160 --> 0:01:21.840 times in four years. Seriously, seriously. This was when I 0:01:21.880 --> 0:01:24.400 was a junior professor and just getting started at the 0:01:24.480 --> 0:01:27.080 Large Hadron Collider and teaching on the West coast of 0:01:27.080 --> 0:01:29.760 the United States. So we actually had a house in 0:01:29.800 --> 0:01:31.760 France and a house in California, and we had to 0:01:31.800 --> 0:01:33.640 go back and forth and back and forth, and back 0:01:33.640 --> 0:01:35.000 and forth and back and forth and back and forth. 0:01:35.160 --> 0:01:37.520 It almost drove my family crazy. Oh my gosh, did 0:01:37.520 --> 0:01:40.720 you have kids at that point? We had two young children, 0:01:40.840 --> 0:01:44.280 one of the whom was born in Switzerland. Oh my goodness. 0:01:44.560 --> 0:01:47.400 I know. It's amazing I'm not divorced. It is. It is. 0:01:48.520 --> 0:01:51.200 I shouldn't have said it is so quickly, but well, 0:01:51.280 --> 0:01:54.080 I'm Kelly Wiener Smith and I'm a parasitologist, and it's 0:01:54.200 --> 0:01:56.560 amazing that I'm not divorced. Also because I moved my 0:01:56.640 --> 0:02:00.680 husband four times during my PhD to different states. But 0:02:00.880 --> 0:02:02.360 you know, I used to think that was bad. And 0:02:02.400 --> 0:02:04.240 now I'm going to go downstairs and tell Zack later 0:02:04.320 --> 0:02:06.920 how easy he has it. So thank you for that. 0:02:06.920 --> 0:02:09.639 That's good. That's my goal is to make other marriages 0:02:09.800 --> 0:02:13.880 look good. We appreciate it. Well. Welcome to the podcast 0:02:14.040 --> 0:02:17.200 Daniel and Jorge Explain the Universe, in which we talk 0:02:17.240 --> 0:02:19.919 about all the crazy and amazing things that we find 0:02:20.000 --> 0:02:22.720 out there in the universe, moving here and there, taking 0:02:22.720 --> 0:02:25.680 our brains from the tiniest little particles down to the 0:02:25.760 --> 0:02:28.760 quantum realm to the vast planets of the outer Solar 0:02:28.800 --> 0:02:32.200 system and all the way to super clusters. Our goal 0:02:32.360 --> 0:02:35.040 is to embrace everything we know and that we don't 0:02:35.080 --> 0:02:38.400 know and explain all of it to you. And as 0:02:38.440 --> 0:02:40.320 you might have guests today on the program, Jorge is 0:02:40.320 --> 0:02:43.120 not here, so we have our fabulous guest host, Kelly 0:02:43.200 --> 0:02:46.120 Weener Smith joining us to talk about all these things 0:02:46.160 --> 0:02:49.359 and ask good questions. Hey, Daniel, I'm excited to be back. 0:02:49.400 --> 0:02:52.440 I had fun lost time. Awesome, great, well, thanks very 0:02:52.480 --> 0:02:55.120 much for joining us. So we started off joking about 0:02:55.240 --> 0:02:58.400 moving houses and moving planets. But this is something I 0:02:58.440 --> 0:03:01.840 think is actually really interesting, is thinking about how the 0:03:02.000 --> 0:03:05.320 planets in our solar system got where they are and 0:03:05.480 --> 0:03:08.680 whether or not they have ever moved. I personally love 0:03:08.760 --> 0:03:10.880 this question because it's one of those questions that, like 0:03:11.240 --> 0:03:13.480 the fact that we have anything that even vaguely resembles 0:03:13.480 --> 0:03:16.480 an answer, makes me sort of proud to be a human. Like, 0:03:16.560 --> 0:03:18.760 how can we even think about these sorts of questions 0:03:18.760 --> 0:03:21.080 and collect data to answer these questions. It just seems 0:03:21.080 --> 0:03:23.360 so mind blowing to begin with the fact that we 0:03:23.400 --> 0:03:26.800 have any answers, even preliminary answers, blows my mind. Well, 0:03:26.840 --> 0:03:29.240 I think it's super fascinating that we even know to 0:03:29.400 --> 0:03:32.560 ask these questions, right, Like, you look at the Solar 0:03:32.600 --> 0:03:34.920 system and we have the planets, and they don't seem 0:03:35.000 --> 0:03:37.800 to be changing from year to year. We have thousands 0:03:37.840 --> 0:03:40.680 of years of astronomical records and so it seems sort 0:03:40.680 --> 0:03:43.880 of stable. So it's sort of absurd even to ask, like, 0:03:44.120 --> 0:03:48.240 could the planets have ever been in another configuration? Could 0:03:48.280 --> 0:03:51.280 the solar system have looked different? It's like very natural 0:03:51.320 --> 0:03:53.680 to think, oh, things are going around the Sun. They've 0:03:53.720 --> 0:03:55.840 been going around the Sun. Of course they were always 0:03:55.880 --> 0:03:59.160 in the same orientation. But something that's happened over the 0:03:59.240 --> 0:04:02.120 last just couple of decades is that we've had a 0:04:02.200 --> 0:04:06.200 chance to glimpse other solar systems. For thousands of years, 0:04:06.200 --> 0:04:09.280 we've only ever seen ours. We had like one example. 0:04:09.760 --> 0:04:12.120 Now we're seeing lots and lots of other solar systems, 0:04:12.400 --> 0:04:15.080 and this gives us a clue that solar systems can 0:04:15.120 --> 0:04:17.960 look different and that there might be a lot of activity, 0:04:18.040 --> 0:04:21.040 that they're actually quite volatile. That is super exciting. So 0:04:21.080 --> 0:04:23.159 for our sample size for these like how many solar 0:04:23.160 --> 0:04:25.480 systems can we see in enough detail where we can 0:04:25.520 --> 0:04:27.680 like count all of the planets and get a bit 0:04:27.680 --> 0:04:29.680 of a sense for what those planets are, like, are 0:04:29.720 --> 0:04:32.960 we talking hundreds, thousands, millions? How big is our data 0:04:32.960 --> 0:04:36.080 set here? It's exciting because it's growing so rapidly, Like 0:04:36.160 --> 0:04:39.080 the first exoplanets were discovered just a few decades ago, 0:04:39.200 --> 0:04:43.200 and now we have thousands, not yet millions. Someday astronomers 0:04:43.160 --> 0:04:45.080 will get to play with the datas that have millions 0:04:45.080 --> 0:04:47.880 of solar systems and ask really detailed questions. But we 0:04:47.920 --> 0:04:50.720 have thousands of solar systems that we can look at 0:04:50.839 --> 0:04:53.080 and we see weird stuff in those solar systems that 0:04:53.120 --> 0:04:55.279 we don't see in our solar system and that makes 0:04:55.360 --> 0:04:57.960 us wonder, like, wait a second, are those solar systems weird? 0:04:58.200 --> 0:05:00.800 Or is our Solar system weird? I need to know 0:05:00.839 --> 0:05:04.720 the answer, And so today on the podcast will be 0:05:04.760 --> 0:05:13.960 asking the question has our Solar system look different? In particular, 0:05:14.200 --> 0:05:18.120 did Jupiter ones have a different orbit? And that's a 0:05:18.160 --> 0:05:20.400 pretty huge question, right because Jupiter is like the biggest 0:05:20.400 --> 0:05:23.400 planet out there, so where it goes has a big impact. 0:05:23.680 --> 0:05:25.679 From one point of view, you could imagine it's basically 0:05:25.680 --> 0:05:28.560 the only planet other than the Sun. Jupiter has like 0:05:29.720 --> 0:05:32.480 of all the mass in the Solar system. Everything else 0:05:32.600 --> 0:05:35.840 is basically a detail compared to Jupiter. So yeah, it's 0:05:35.839 --> 0:05:38.279 a big deal. If Jupiter had been in a different place, 0:05:38.480 --> 0:05:41.560 everything would be different, and so as usual, I was 0:05:41.600 --> 0:05:44.919 curious whether people had this in their minds, like, have 0:05:45.120 --> 0:05:48.280 people imagine the possibility that Jupiter could be in a 0:05:48.320 --> 0:05:50.760 different place? Is that something people have thought about, have 0:05:50.960 --> 0:05:53.520 heard about? So I went out there to the wilds 0:05:53.560 --> 0:05:56.039 of the Internet and I asked people, Hey, do you 0:05:56.040 --> 0:05:58.800 know the answer to this tough physics question that astronomers 0:05:58.839 --> 0:06:02.400 are struggling over. Use no preparation, no googling allowed, Just 0:06:02.480 --> 0:06:04.840 tell me off the top of your head. Here's what 0:06:04.920 --> 0:06:09.960 people had to say. I guess No, there were impacts 0:06:10.400 --> 0:06:17.960 off I guess asteroids and or comets, and I may 0:06:17.960 --> 0:06:21.599 be even bigger objects in the past. So I think 0:06:22.560 --> 0:06:28.279 the orbit of Jupiter was a different one two beion 0:06:28.400 --> 0:06:31.800 years ago. No, I think it was, but I think 0:06:31.800 --> 0:06:34.080 it used to be a lot closer and then it 0:06:34.279 --> 0:06:39.560 moved out through collisions and the collisions, I think Jupiter 0:06:39.680 --> 0:06:43.240 used to be in a different orbit. I know Uranus 0:06:43.600 --> 0:06:47.000 rotates about its access in a way that sideways compared 0:06:47.040 --> 0:06:51.120 to the other planets. Well, I'm not sure if what 0:06:51.160 --> 0:06:54.960 I think happened, is that Uranus and Jupiter collies at 0:06:55.000 --> 0:06:58.479 some point. I suspect that Jupiter has been in its 0:06:58.560 --> 0:07:04.200 current orbit for quite some time, speaking on you know, 0:07:04.240 --> 0:07:07.640 the scale of the formation of our Solar system, but 0:07:07.680 --> 0:07:09.880 I would not at all be surprised if it had 0:07:10.000 --> 0:07:13.800 moved around somewhat during the early formation period of our 0:07:13.840 --> 0:07:20.880 solar system. Would say, yes, well, nothing is permanent, so 0:07:20.920 --> 0:07:23.480 I guess it's at the origin it was part of 0:07:23.520 --> 0:07:30.680 the the Sun or giant cloud of gas. But to me, well, 0:07:30.720 --> 0:07:35.000 it's quite stable orbits, and I don't see why each change, 0:07:35.040 --> 0:07:37.600 except for minor changes such as a collision with that 0:07:39.120 --> 0:07:44.800 other objects. But I would say yes, no, no, Um. 0:07:45.560 --> 0:07:51.200 Jupiter at some point was sitting towards the Sun, but 0:07:51.600 --> 0:08:01.200 it's kinda got locked in by Saturn, probably interaction with 0:08:01.400 --> 0:08:08.440 settled um, something like that. I don't know, you caught me. 0:08:08.480 --> 0:08:11.760 I'll guard here. I don't think that Jupiter has always 0:08:11.800 --> 0:08:13.880 been in its current orbit. I think it formed much 0:08:13.920 --> 0:08:17.240 closer to the Sun, and as it migrated out into 0:08:17.320 --> 0:08:19.840 the Solar System, it cleared a lot of the debris 0:08:19.880 --> 0:08:24.320 and comets and asteroids and dust and everything out of 0:08:24.360 --> 0:08:26.920 its way um and made things a little bit more 0:08:26.960 --> 0:08:30.080 stable here in the inner Solar system, so life could form. 0:08:30.400 --> 0:08:32.320 But I don't think that it started out where it 0:08:32.320 --> 0:08:35.640 currently is. Somebody say no, but I guess, being it's 0:08:35.679 --> 0:08:38.480 so big, it could well have picked up a lot 0:08:38.559 --> 0:08:42.120 of stuff through its time, and as it um, you know, 0:08:42.160 --> 0:08:44.920 it picks up more stuff gets impacted, and I guess 0:08:45.120 --> 0:08:49.240 it's gravitational forces would interact with other planets and stuff around, 0:08:49.840 --> 0:08:52.239 so therefore it get knocked off and moved off its 0:08:52.720 --> 0:08:57.439 little but quite regularly. Maybe, I think almost certainly no. UM. 0:08:57.480 --> 0:09:00.600 I think the current model of how those those system 0:09:00.679 --> 0:09:07.679 was formed UM actually relies on Jupiter migrating inward closer 0:09:07.720 --> 0:09:11.440 to the Sun and then further away. I believe Jupiter 0:09:11.600 --> 0:09:15.200 has moved from its original orbit. I think the original 0:09:15.320 --> 0:09:18.720 orbit was closer to the Sun. All right, Wow, those 0:09:18.840 --> 0:09:22.600 are some great answers from our listeners. When you heard 0:09:22.679 --> 0:09:25.560 that this was even a question that people were thinking about, 0:09:26.000 --> 0:09:29.120 did you have a like, oh my gosh moment or 0:09:29.480 --> 0:09:31.839 did it just seem like an obvious question for you 0:09:31.920 --> 0:09:34.400 to be asking. I had an oh my gosh moment 0:09:34.440 --> 0:09:36.880 and a hope because I thought, oh, that would be 0:09:37.000 --> 0:09:40.880 super cool if Jupiter wasn't always in its current orbit. 0:09:41.040 --> 0:09:43.439 Because one of the fun things for me in science 0:09:43.640 --> 0:09:46.920 is revealing surprises. Right If you ask a question and 0:09:46.920 --> 0:09:49.000 then the answer is yeah, it's kind of boring Jupiter 0:09:49.080 --> 0:09:51.280 has always been there. That's not nearly as fun as 0:09:51.480 --> 0:09:54.080 Oh my gosh, it turns out there's a crazy history 0:09:54.120 --> 0:09:56.840 here and we have revealed it. Like you were saying earlier, 0:09:56.840 --> 0:10:00.320 it's incredible that we could, like by gathering small lose 0:10:00.679 --> 0:10:05.120 left by these crazy cosmic events, actually reconstruct something that 0:10:05.200 --> 0:10:07.920 happened billions of years ago. It's like solving a billion 0:10:08.000 --> 0:10:10.599 year old murder mystery. As a biologist, every once in 0:10:10.640 --> 0:10:12.800 a while we will have discussions about like what makes 0:10:13.120 --> 0:10:16.160 humans different than other animals, And you know, clearly being 0:10:16.200 --> 0:10:18.960 able to think about questions like this is one of 0:10:19.000 --> 0:10:22.040 those things that like, certainly we're the only species who's 0:10:22.040 --> 0:10:27.240 wondering that on our planet exactly. So it's super fun. 0:10:27.280 --> 0:10:29.480 And I was really hoping that the answer would be 0:10:29.520 --> 0:10:32.600 something crazy. So it's pretty interesting to learn about. And 0:10:32.760 --> 0:10:37.160 I've also really been enjoying following this Excel planet discovery 0:10:37.280 --> 0:10:41.000 seeing these other solar systems, these other like potential homes 0:10:41.000 --> 0:10:43.920 for aliens where life could be really different because the 0:10:43.960 --> 0:10:46.760 planets are so different from ours. You know, we're sort 0:10:46.760 --> 0:10:49.559 of like trapped in this colloquial way of thinking that 0:10:49.600 --> 0:10:52.000 our kinds of planets are the kinds of planets you have, 0:10:52.080 --> 0:10:55.040 like small rocky planets and the inner Solar system and 0:10:55.160 --> 0:10:57.880 big gas giants and the outside and now it's possible 0:10:57.920 --> 0:11:02.000 to imagine other kinds of areas. So is our configuration 0:11:02.160 --> 0:11:05.480 a typical configuration. It turns out it's not. When we 0:11:05.520 --> 0:11:08.240 look at other solar systems, we see something really weird. 0:11:08.600 --> 0:11:10.960 First of all, we see that most solar systems have 0:11:11.000 --> 0:11:14.000 a lot more planets very close to their star, Like 0:11:14.280 --> 0:11:17.960 between Mercury and the Sun there's basically nothing, But in 0:11:18.000 --> 0:11:21.080 other solar systems there are lots of planets packed in there. 0:11:21.320 --> 0:11:25.079 And in particular, we find these things called hot jupiters. 0:11:25.080 --> 0:11:27.720 Not hot because they're like you know, big on Instagram 0:11:27.800 --> 0:11:31.440 or they're really curvy, hot because they're really close to 0:11:31.559 --> 0:11:34.320 the Sun. Like, we find these planets in other solar 0:11:34.320 --> 0:11:38.520 systems that are really big, like Jupiter size and gas planets, 0:11:39.000 --> 0:11:42.360 but they orbit the star in just like hours or days, 0:11:42.520 --> 0:11:45.440 and like a fraction of the distance between the Sun 0:11:45.520 --> 0:11:48.560 and mercury. So that's a really weird phenomenon to see. 0:11:48.640 --> 0:11:51.560 Shouldn't they like suck each other into each other pretty quickly? 0:11:51.800 --> 0:11:53.520 What's the good physics word for that? How do they 0:11:53.559 --> 0:11:56.520 stay separated if they're both huge and attracting each other 0:11:56.520 --> 0:11:58.800 and are so close now, suck each other in is 0:11:58.840 --> 0:12:01.800 exactly they're all right physics word to use, And that's 0:12:01.800 --> 0:12:04.120 exactly the question people are asking. They're like, hold on 0:12:04.160 --> 0:12:06.400 a second, how do you get such a big planet 0:12:06.640 --> 0:12:09.400 so close to the Sun? Can it last very long? 0:12:09.400 --> 0:12:12.480 Are we seeing something just before it dies? Or can 0:12:12.520 --> 0:12:15.480 that be a stable configuration? And the models suggests that 0:12:15.520 --> 0:12:17.600 they can't have been born that close to the Sun 0:12:17.640 --> 0:12:20.040 and they can't last there very long. And that's the 0:12:20.080 --> 0:12:23.760 clue that got everybody talking and thinking about whether planets 0:12:23.800 --> 0:12:26.840 are moving, because they suspect that these hot jupiters form 0:12:26.960 --> 0:12:29.520 further out and then get sucked in, and so we're 0:12:29.559 --> 0:12:32.480 witnessing sort of like the end of the life cycle 0:12:32.480 --> 0:12:35.080 of these planets before they either get torn apart or 0:12:35.160 --> 0:12:37.840 pulled in. And that's a clue that, like solar systems 0:12:37.840 --> 0:12:40.760 are volatile, there is stuff going on. It's not just 0:12:40.840 --> 0:12:44.000 everybody sedately driving in their lane for billions of years? 0:12:44.720 --> 0:12:46.760 Is Jupiter going to get sucked into our Sun? Not 0:12:46.840 --> 0:12:50.600 before the Sun explodes? Right? Are you worried about Jupiter? 0:12:50.640 --> 0:12:53.120 Have you invested in real estate on Jupiter? Well, you know, 0:12:53.160 --> 0:12:55.679 I was thinking about it. We've been reading about space settlements, 0:12:55.720 --> 0:12:58.120 but no, obviously not nobody's gonna go live on Jupiter. 0:12:58.200 --> 0:13:00.600 But maybe it's moons. I went to read I fantastic 0:13:00.640 --> 0:13:04.120 series and science fiction novels about a civilization in the 0:13:04.200 --> 0:13:06.920 upper clouds of Jupiter. I think it was called Bio 0:13:07.040 --> 0:13:10.240 of a Space Tyrant Man. I loved those books when 0:13:10.240 --> 0:13:13.479 I was a teenager. It was so like fantastically imagined. 0:13:13.800 --> 0:13:15.720 So I hope that one day humans do get to 0:13:15.720 --> 0:13:17.040 live on Jupiter, and I hope that we get to 0:13:17.080 --> 0:13:19.880 keep Jupiter because I like it. I mean, Jupiter is pretty. 0:13:20.040 --> 0:13:22.679 For all the press that like Mars gets recently, Jupiter 0:13:22.760 --> 0:13:25.199 is a gorgeous planet. So maybe we should start by 0:13:25.240 --> 0:13:27.960 thinking about our solar system and understanding of what we 0:13:28.040 --> 0:13:31.160 know about Jupiter, like where it was made, how it 0:13:31.280 --> 0:13:33.600 got formed, and that can give us a clue for 0:13:33.679 --> 0:13:37.040 like why people think there might have been crazy stuff 0:13:37.080 --> 0:13:39.880 going on in our solar system. At the very beginning 0:13:39.880 --> 0:13:42.600 of time. Alright, so tell me about how Jupiter got 0:13:42.640 --> 0:13:44.800 to be where it is. Yes, so we think Jupiter 0:13:44.880 --> 0:13:48.520 is probably born out in the outer Solar system. There's 0:13:48.559 --> 0:13:51.240 this point in the Solar system called the ice line, 0:13:51.800 --> 0:13:55.480 where beyond that it's cold enough for ice to form 0:13:55.640 --> 0:13:58.320 and to stay melted and basically be like a rock 0:13:58.559 --> 0:14:01.800 that you can use and building planetary cores. And it's 0:14:01.800 --> 0:14:04.480 about like three and a half AU. Will remember a 0:14:04.679 --> 0:14:08.520 U isn't one astronomical units the distance between the Sun 0:14:08.640 --> 0:14:11.439 and the Earth, So three and a half times the 0:14:11.559 --> 0:14:13.800 radius of the Earth. Beyond that is the ice line, 0:14:13.880 --> 0:14:16.520 or some people call it the snow line, and out 0:14:16.559 --> 0:14:19.840 there it's easier to make big planets because there's ice 0:14:19.880 --> 0:14:23.320 available to add to your core. So we think that 0:14:23.560 --> 0:14:26.880 the way the Solar system started obviously, have a big 0:14:26.920 --> 0:14:30.000 blob of gas and dust and some shock wave comes 0:14:30.040 --> 0:14:32.200 through it and you get the spark that begins the 0:14:32.200 --> 0:14:34.960 formation of the whole Solar system, which basically means the Sun. 0:14:35.400 --> 0:14:37.880 But the Sun has gathered together a huge amount of 0:14:37.880 --> 0:14:41.160 gas and it has around it a big swirling disk, 0:14:41.480 --> 0:14:43.720 and that's the disc that's going to provide the material 0:14:43.960 --> 0:14:47.200 that forms all of the planets now out past the 0:14:47.240 --> 0:14:51.000 snow line, there's also ice in there. So the ice 0:14:51.080 --> 0:14:53.440 and the rock and the dust gathered together to make 0:14:53.440 --> 0:14:57.760 these protoplanetary cores. They start pulling themselves together and that 0:14:57.880 --> 0:15:01.040 sort of seeds the planets. And so we ended up 0:15:01.080 --> 0:15:05.840 with what four planets out past the ice line? Is 0:15:05.880 --> 0:15:08.640 that pretty common? Like that number and like the size 0:15:08.640 --> 0:15:10.160 of our planets does that match up with what we 0:15:10.160 --> 0:15:12.760 see in other solar systems. We don't know the answer 0:15:12.800 --> 0:15:15.040 to that yet, we haven't seen enough. But also remember 0:15:15.080 --> 0:15:17.040 that we can see a bunch of solar systems, but 0:15:17.120 --> 0:15:19.360 we're not that great at seeing all of them. And 0:15:19.400 --> 0:15:22.240 there's certain kinds of solar systems that are easier to see. 0:15:22.360 --> 0:15:25.880 Like it's easier to see big planets that are closer 0:15:25.920 --> 0:15:29.520 to their Sun because they block more of the Sun's light. 0:15:29.960 --> 0:15:32.080 The way we see these exoplanets is that they block 0:15:32.160 --> 0:15:34.920 the light of their Sun or they tug gravitationally on 0:15:34.960 --> 0:15:37.800 the Sun. So big planets are easier to see. Close 0:15:37.840 --> 0:15:40.560 up planets are easier to see, so far out planets 0:15:40.640 --> 0:15:43.880 harder to spot. Far out small planets harder to spot. 0:15:44.240 --> 0:15:46.800 Does that mean that like super slow moving things we 0:15:46.880 --> 0:15:49.240 probably don't have good data on yet because we wouldn't 0:15:49.240 --> 0:15:51.280 have had a chance to see them pass in front 0:15:51.280 --> 0:15:53.480 of the sun or tug it as it moves around 0:15:53.520 --> 0:15:56.280 to the side. That's exactly right, Yeah, we have to 0:15:56.320 --> 0:15:59.080 watch these things cross their sun, and so basically it's 0:15:59.120 --> 0:16:01.200 best if you can see and pass a few times 0:16:01.200 --> 0:16:03.560 so you can see like a regular interval, so the 0:16:03.600 --> 0:16:06.600 equivalent of several of their years. But if their years 0:16:06.640 --> 0:16:09.360 take like, you know, a hundred earth years to go around, 0:16:09.400 --> 0:16:11.600 then we're not going to have had time to see it. 0:16:11.640 --> 0:16:15.160 So slow moving things, small things, things far from their 0:16:15.200 --> 0:16:17.720 son are harder to see. So that's a long way 0:16:17.760 --> 0:16:20.440 of saying we don't have an unbiased picture of what's 0:16:20.440 --> 0:16:22.480 going on in these other solar systems. And we have 0:16:22.520 --> 0:16:25.000 to try to play this game of wondering, like, well, 0:16:25.040 --> 0:16:26.920 if we see only one of them, do we imagine 0:16:26.920 --> 0:16:29.160 that there are a thousand? Or if we only see 0:16:29.200 --> 0:16:30.880 two of those, do we imagine there are a hundred. 0:16:30.920 --> 0:16:33.760 We have to estimate like how good we are seeing them, 0:16:34.000 --> 0:16:36.240 so we can like invert that and imagine what's actually 0:16:36.280 --> 0:16:38.760 there that we're missing. But there's a lot that we're missing. 0:16:38.760 --> 0:16:42.120 Still interesting Yeah, it's really fascinating. And so that's why 0:16:42.160 --> 0:16:44.960 we focus on our solar system because it's here, it's relevant, 0:16:45.000 --> 0:16:47.000 and it's one that we can study in great detail. 0:16:47.120 --> 0:16:49.280 But those other solar systems do give us a lot 0:16:49.360 --> 0:16:52.000 of clues. Back to jo Butter, we think that it 0:16:52.120 --> 0:16:54.920 must have had to form and the outer Solar System 0:16:55.200 --> 0:16:57.640 because that's basically the only place to make these big 0:16:57.680 --> 0:17:00.920 gas giants. I mean, you need now of ice and 0:17:01.120 --> 0:17:03.560 enough rock to pull together to make this big core 0:17:03.880 --> 0:17:06.600 to grab a bunch of gas. Remember, everything in the 0:17:06.600 --> 0:17:09.480 Solar system is competing with the Sun. In the inner 0:17:09.520 --> 0:17:11.960 Solar system, is not that much gas left because the 0:17:12.040 --> 0:17:13.840 Sun has slurped it all up. So to make a 0:17:13.880 --> 0:17:16.280 gas giant, really have to be far enough away from 0:17:16.280 --> 0:17:18.840 the Sun to get any of the gas, and you 0:17:18.880 --> 0:17:21.199 have to be past the snow line, so you can 0:17:21.240 --> 0:17:24.320 have ice accumulated in your core and get big enough 0:17:24.320 --> 0:17:26.400 that you can grab some of the gas before all 0:17:26.480 --> 0:17:30.880 spirals into the Sun. Anyway, Okay, so Jupiter was formed 0:17:30.920 --> 0:17:33.439 in the outer Solar System and it's still in the 0:17:33.440 --> 0:17:37.160 outer Solar system. So after the break, let's talk about 0:17:37.160 --> 0:17:54.600 why we think it moved. Okay, so Jupiter is where 0:17:54.640 --> 0:17:56.679 we would expect it to be, given how we expect 0:17:56.720 --> 0:17:59.879 that it formed, So why would we suspect that it 0:18:00.080 --> 0:18:02.359 had moved at any point. Yeah, it seems at first 0:18:02.359 --> 0:18:04.640 like it might be a simple story. Right, Jupiter had 0:18:04.680 --> 0:18:07.600 to form somewhere in the neighborhood where it is today, 0:18:07.880 --> 0:18:10.159 and so the simplest explanation is, well, maybe it just 0:18:10.280 --> 0:18:12.840 formed there and stayed there. Why do we imagine it 0:18:12.920 --> 0:18:15.560 ever took a tour in the inner Solar System? And 0:18:15.600 --> 0:18:18.520 the reason is that the inner Solar System looks weird, 0:18:18.600 --> 0:18:22.480 like we can't explain the Inner Solar System in that picture. 0:18:22.480 --> 0:18:25.199 Our models of how the Solar System came together. We 0:18:25.280 --> 0:18:27.840 run a bunch of like simulations and try to explain 0:18:28.080 --> 0:18:31.040 how we got Venus and Earth and Mars. None of 0:18:31.080 --> 0:18:33.720 the models that we run actually match up with what 0:18:33.800 --> 0:18:37.200 we see. How are they different? Well, in particular, Mars 0:18:37.320 --> 0:18:40.320 is really weird, Like Mars is a nice little planet, 0:18:40.480 --> 0:18:43.600 but it's really small, Like Mars is like ten percent 0:18:43.800 --> 0:18:47.120 of the mass of the Earth. That's a really small planet. 0:18:47.320 --> 0:18:49.800 And in all our models of the Solar System, Mars 0:18:49.800 --> 0:18:52.119 should be a lot bigger, like as you get further 0:18:52.200 --> 0:18:55.240 out from the Sun, there's more material available because the 0:18:55.240 --> 0:18:57.960 Sun hasn't stolen at all, and so you expect a 0:18:58.080 --> 0:19:00.440 planet forming around there to be like about the size 0:19:00.440 --> 0:19:02.480 of the Earth or even bigger. You know, as you 0:19:02.520 --> 0:19:05.040 go to the outer Solar System, things get bigger, right, 0:19:05.080 --> 0:19:08.680 So why is Mars so tiny? Why is it so little? 0:19:08.960 --> 0:19:10.840 So as you get farther out in the Solar System, 0:19:10.880 --> 0:19:13.080 things should get bigger. But Jupiter is the biggest and 0:19:13.080 --> 0:19:15.679 it's not the most far out, So why is Saturn 0:19:15.720 --> 0:19:18.200 smaller than Jupiter? Then? Oh, yeah, that's a great question. 0:19:18.320 --> 0:19:20.600 There's a whole other fun story about a sounder Jupiter, 0:19:20.640 --> 0:19:24.040 maybe switching locations and the whole dance of Uranus and 0:19:24.119 --> 0:19:26.440 Neptune that they might have done. But you're right, there's 0:19:26.440 --> 0:19:28.600 a balance there because you want to be far enough 0:19:28.600 --> 0:19:31.160 away from the Sun so it doesn't steal all the material, 0:19:31.359 --> 0:19:33.320 but as you get even further away from the Sun 0:19:33.480 --> 0:19:36.440 you run out of material also, right, Obviously there aren't 0:19:36.480 --> 0:19:39.359 like super giant planets twice as far away as Jupiter, 0:19:39.760 --> 0:19:42.160 and so this is something of like a peak location there. 0:19:42.320 --> 0:19:44.400 Jupiter is probably sitting right there in the spot where 0:19:44.400 --> 0:19:46.920 you can make the biggest planet. But the question remains 0:19:46.960 --> 0:19:49.480 like why is Mars so a little what happened to 0:19:49.600 --> 0:19:52.919 make Mars so tiny? And it's not just Mars? Like 0:19:52.960 --> 0:19:55.960 the asteroid belt is also kind of weird, like we 0:19:56.000 --> 0:19:58.800 don't really understand how it formed the way it did. Again, 0:19:59.200 --> 0:20:01.439 we run these model let's start from just the gas cloud, 0:20:01.640 --> 0:20:03.760 and you don't get an asteroid belt that looks the 0:20:03.760 --> 0:20:07.160 way it does. Specifically, our asteroid belt is weird because 0:20:07.200 --> 0:20:09.879 it has both like rocky objects that seems like they 0:20:09.880 --> 0:20:12.560 came from the inner Solar System. Plus they have a 0:20:12.600 --> 0:20:15.000 bunch of icy objects, the kinds of things you would 0:20:15.040 --> 0:20:18.000 find like in the Kuiper Belt or deeper further out 0:20:18.000 --> 0:20:20.800 in the Solar system. So there're these like pieces of 0:20:20.840 --> 0:20:23.080 evidence you were talking earlier about like how could we 0:20:23.160 --> 0:20:26.080 possibly find clues about things that happened so long ago? 0:20:26.359 --> 0:20:28.800 Like these are the things that have puzzled scientists for 0:20:28.840 --> 0:20:32.280 a long time. So is the asteroid belt inside the 0:20:32.320 --> 0:20:35.720 ice line or on the Jupiter side of the ice line? Yeah, 0:20:35.760 --> 0:20:38.240 the asteroid belt is really weird. Actually part of his 0:20:38.440 --> 0:20:41.440 inside the ice line, the part that's like closer to Mars, 0:20:41.480 --> 0:20:44.280 remember it sits between Mars and Jupiter. But it also 0:20:44.320 --> 0:20:46.680 extends kind of far out, and part of it actually 0:20:47.240 --> 0:20:50.600 is in orbit with Jupiter. Like it's not all between 0:20:50.720 --> 0:20:53.919 Mars and Jupiter. There's these big blobs of asteroids that 0:20:53.960 --> 0:20:57.000 are in Jupiter's orbit just sort of like rotated away 0:20:57.000 --> 0:20:59.520 from them, like you know, thirty degrees around the thirty 0:20:59.520 --> 0:21:02.040 degrees the other direction, and stuff is sort of like 0:21:02.080 --> 0:21:04.840 sloshing back and forth. So some of it's definitely out 0:21:04.880 --> 0:21:07.840 there past the ice line and can stay frozen, and 0:21:07.880 --> 0:21:11.440 some of it's a little bit closer. Interest. Yeah, and 0:21:11.520 --> 0:21:14.520 so we have these mysteries, and I love that. This 0:21:14.600 --> 0:21:16.920