WEBVTT - Is there Uranium on Uranus? 0:00:08.680 --> 0:00:13.440 Hey, Kelly, are you a fan of astronomy humor? It 0:00:13.480 --> 0:00:17.400 depends as long as we're not making jokes about urinus. Well, 0:00:17.440 --> 0:00:20.079 we'll have to try to avoid falling into that particular hole. 0:00:20.200 --> 0:00:24.079 But personally, I love a good astronomy pun. I have 0:00:24.200 --> 0:00:28.760 more of a plutonic relationship. Oh no, did you just 0:00:28.840 --> 0:00:32.640 make that joke up or did you have to plan it? Okay, 0:00:32.680 --> 0:00:36.360 I've got one for you. Alright. Why don't stars go 0:00:36.440 --> 0:00:41.040 to university? Alright? Why? Because they've already got millions of degrees. 0:00:44.880 --> 0:01:03.600 I'm sorry. Hi, I'm Daniel. I'm a particle physicist and 0:01:03.680 --> 0:01:07.160 a professor at UC Irvine, and I will always laugh 0:01:07.240 --> 0:01:10.800 at astronomy puns. Hi, I'm Kelly Weener Smith. I'm a 0:01:10.800 --> 0:01:14.200 parasitologist at Rice University, and I think my last name 0:01:14.240 --> 0:01:17.280 is hilarious. So I will always laugh at both parasitology 0:01:17.280 --> 0:01:20.600 puns and scatological humor. There's gotta be a lot of 0:01:20.600 --> 0:01:23.080 good puns when you're talking about worms and bugs and 0:01:23.120 --> 0:01:26.880 things that crawling inside other things. So and they get, 0:01:27.200 --> 0:01:29.720 but we try to keep this podcast family friendly, and 0:01:29.760 --> 0:01:32.720 so we will spare you most of those and so 0:01:32.840 --> 0:01:36.520 welcome to the podcast. Daniel and Jorgey explain the Universe, 0:01:36.680 --> 0:01:39.400 in which we talk about all the incredible and amazing 0:01:39.480 --> 0:01:42.480 things out there in the universe. We crack jokes about 0:01:42.480 --> 0:01:44.640 the silly names they get, but we have a deep, 0:01:44.760 --> 0:01:47.640 deep love for the mysteries of the universe and we 0:01:47.680 --> 0:01:49.720 want to explore all of them with you. We think 0:01:49.800 --> 0:01:53.520 it's incredible. It's amazing that this universe is understandable at 0:01:53.520 --> 0:01:56.120 all to our tiny human brains. We want to push 0:01:56.160 --> 0:01:58.960 forward this effort and bring this understanding of the universe 0:01:59.040 --> 0:02:02.040 into all of our minds because everybody out there has 0:02:02.120 --> 0:02:05.120 questions about how the universe works and wants to know 0:02:05.160 --> 0:02:06.880 where it came from and where it's going to go 0:02:06.960 --> 0:02:09.560 and how it all fits together. So thanks very much 0:02:09.600 --> 0:02:13.200 for joining us on our journey of curiosity. My typical 0:02:13.240 --> 0:02:15.800 co host Orge isn't with us today, and so we 0:02:15.880 --> 0:02:20.480 have are wonderful and hilarious and very punny co host Kelly. 0:02:21.120 --> 0:02:23.560 Thanks for joining us. Kelly, thanks for having me. I'm 0:02:23.600 --> 0:02:27.520 super excited about today's question. Awesome, And you know, on 0:02:27.560 --> 0:02:30.320 this podcast we often talk about things that are very 0:02:30.360 --> 0:02:34.200 far away. We're very distant in space and time, but 0:02:34.280 --> 0:02:37.519 we also have questions about things that happen in our backyard. 0:02:37.600 --> 0:02:40.960 We're very curious about the nature of our environment, how 0:02:41.000 --> 0:02:43.280 the Earth formed, how the Solar system formed, how it 0:02:43.360 --> 0:02:46.360 all came together. You have a very broad definition of 0:02:46.600 --> 0:02:51.400 in our backyard. That's true, I guess, parasitologist, when you 0:02:51.400 --> 0:02:56.040 talk about backyard, you mean literally like what's inside my fence, right, 0:02:56.160 --> 0:03:00.720 That's exactly what I mean. Cosmologically speaking, though, our backyard 0:03:00.760 --> 0:03:03.400 to me is like the stuff that formed with us, 0:03:03.400 --> 0:03:05.760 that has like a common history that we could like 0:03:05.800 --> 0:03:07.800 go and visit it and dig up something on an 0:03:07.840 --> 0:03:10.680 asteroid and from that learned something about the Earth. We 0:03:10.720 --> 0:03:13.359 have like answers in common, and actually later on in 0:03:13.400 --> 0:03:15.600 the episode, we're gonna hear a really cool story about 0:03:15.639 --> 0:03:19.000 how asteroids told us something about the history of our 0:03:19.040 --> 0:03:22.160 planet and how uranium was involved. But you might look 0:03:22.200 --> 0:03:24.280 at our planet and think, like, m it looks kind 0:03:24.280 --> 0:03:26.360 of different from the other planets. I mean, like, we have, 0:03:26.480 --> 0:03:29.080 for example, a nice surface, and we have water, and 0:03:29.120 --> 0:03:31.440 we have an atmosphere, and you know the Moon doesn't 0:03:31.440 --> 0:03:34.960 have that, and Jupiter and Saturn and Neptune and Urine 0:03:35.000 --> 0:03:37.480 is these planets all look very different from ours, and 0:03:37.520 --> 0:03:40.000 so you might wonder like did they form differently? Are 0:03:40.040 --> 0:03:42.080 they made of the same stuff? What do we really 0:03:42.120 --> 0:03:43.840 know about what's going on in the rest of the 0:03:43.840 --> 0:03:47.160 Solar System and how is it all connected? And so 0:03:47.280 --> 0:03:49.240 we thought a fun question to dig into would be 0:03:49.280 --> 0:03:52.320 to ask questions about what's going on inside these other 0:03:52.360 --> 0:03:54.920 big planets. That's a great question. I've been reading a 0:03:54.920 --> 0:03:57.080 bit about what is on the various different planets that 0:03:57.120 --> 0:04:00.400 I'm always surprised by, well by how much for lap 0:04:00.440 --> 0:04:02.640 there tends to be, but also the important things that 0:04:02.680 --> 0:04:05.160 seem to be missing, like carbon on the Moon. It's 0:04:05.160 --> 0:04:07.240 gonna be really hard to grow plants on the Moon 0:04:07.240 --> 0:04:10.640 with no carbon. Do you have plans to go plants 0:04:10.640 --> 0:04:13.040 on the Moon? I do not, but plenty of people do. 0:04:13.440 --> 0:04:17.040 Fun fact, the most concentrated carbon in the Moon is 0:04:17.160 --> 0:04:20.480 probably the bags of feces that the Apollo astronauts left behind. 0:04:21.160 --> 0:04:23.440 And this is why I don't get invited to parties. 0:04:25.720 --> 0:04:29.279 Are those frozen remains from the astronauts also useful because 0:04:29.320 --> 0:04:32.760 they contain like the microbiome of those astronauts from what 0:04:32.800 --> 0:04:35.400 they were eating like forty years ago. I don't think 0:04:35.440 --> 0:04:38.279 that microbiome is going to be useful for much anymore. 0:04:38.520 --> 0:04:41.480 But I also think that according to the Outer Space Treaty, 0:04:41.720 --> 0:04:45.480 those bags of feces technically still belong to NASA, So 0:04:46.040 --> 0:04:47.800 I guess it depends on what NASA wants to do 0:04:47.839 --> 0:04:50.159 with them. Well, if they've become an important resource, we 0:04:50.160 --> 0:04:54.520 could end up with an international or interstellar war sparked 0:04:54.520 --> 0:04:59.640 by astronaut remains. So why hasn't someone written about that 0:05:00.680 --> 0:05:04.359 massive lost opportunity? Contact us if you need book ideas, Guys, 0:05:05.640 --> 0:05:07.880 I'm sure somebody out there has written that science fiction 0:05:07.960 --> 0:05:11.599 story already. But we're not so interested in where astronauts 0:05:11.640 --> 0:05:14.800 have left their remains. Were interested in whether there are 0:05:14.920 --> 0:05:18.080 really big, heavy materials on other planets. Some of the 0:05:18.080 --> 0:05:20.240 most exotic, some of the most amazing, some of the 0:05:20.320 --> 0:05:23.320 weirdest things we find on Earth. We are wondering if 0:05:23.360 --> 0:05:26.719 they also exist on other planets. And so today we 0:05:26.760 --> 0:05:36.240 will be asking is there uranium on Uranus? Now? I 0:05:36.279 --> 0:05:40.000 notice you very carefully pronouncing the title of the planet Uranus. Yes, 0:05:40.160 --> 0:05:42.800 very carefully. I have a seven year old at home, 0:05:42.960 --> 0:05:45.440 and so I have to be careful to not edge 0:05:45.480 --> 0:05:49.000 anywhere near that word, otherwise I can't talk to her 0:05:49.040 --> 0:05:52.120 for about three hours because she's laughing too hard and 0:05:52.200 --> 0:05:54.400 me as well. But is there an option to pronounce 0:05:54.480 --> 0:05:58.000 uranium with the same rhythm, like could you say uranium 0:05:58.360 --> 0:06:02.880 your how you even say that uranium? Uran question? I've 0:06:02.960 --> 0:06:05.719 never thought about it. I don't know. Is there uranium 0:06:05.800 --> 0:06:09.000 on Uranus? Sorry, no, we got it backwards. Is there 0:06:11.160 --> 0:06:15.039 is there urinium? Is there uranium on Uranus? There we go, 0:06:17.200 --> 0:06:19.360 and the rest of the podcast would just be us giggling. 0:06:23.040 --> 0:06:28.320 Control yourself. But it is a serious scientific question whether 0:06:28.920 --> 0:06:32.080 uranium only exists on Earth, because you can imagine in 0:06:32.080 --> 0:06:34.320 the future, as we're exploring the Solar System, we might 0:06:34.440 --> 0:06:38.240 want to mind other planets for useful minerals as we're 0:06:38.279 --> 0:06:41.279 powering our spaceships out of the Solar System or even 0:06:41.320 --> 0:06:43.560 around the Solar System. And also to me, it's just 0:06:43.600 --> 0:06:45.880 a fun question to think about, first of all, how 0:06:45.920 --> 0:06:47.720 it was made in the universe and how it is 0:06:47.760 --> 0:06:49.960 distributed and where it ended up. You know, is the 0:06:49.960 --> 0:06:52.640 Earth unique in its collection of heavy metals or is 0:06:52.720 --> 0:06:56.240 maybe uranium like very common on Urinus and other planets. 0:06:56.440 --> 0:06:58.760 So I think the more than just a giggle factor. 0:06:58.880 --> 0:07:03.040 This is a serious sign diffic question, very serious, very serious. Yes, 0:07:03.080 --> 0:07:05.320 so putting on our serious faces. I went out there 0:07:05.320 --> 0:07:08.120 and I asked folks on the internet listeners to this 0:07:08.200 --> 0:07:12.040 show whether they thought there was uranium on Uranus. So, 0:07:12.080 --> 0:07:14.360 if you would like to participate for future rounds the 0:07:14.360 --> 0:07:17.640 podcast and like to play along at home, please write 0:07:17.680 --> 0:07:20.640 to me two questions at Daniel and Jorge dot com. 0:07:20.720 --> 0:07:23.400 I'd love to hear your answers. I know you're out there. 0:07:23.480 --> 0:07:25.720 You've been listening to the podcast for years and they've 0:07:25.760 --> 0:07:28.760 never written in. Today is the day you right in. 0:07:29.040 --> 0:07:30.720 So think about it for a minute before you listen 0:07:30.720 --> 0:07:34.960 to these answers. Do you think there's uranium on Uranus? 0:07:34.960 --> 0:07:39.560 Here's what people had to say. Earth has it, and 0:07:40.920 --> 0:07:48.840 all the other planets like Mercury, Mars, Asteroids and all 0:07:48.960 --> 0:07:55.280 that have uranium, Uranus being in our Solar system should 0:07:55.320 --> 0:07:57.920 have it too. I would say that, yes, there definitely 0:07:57.920 --> 0:08:02.080 has to be at least one atom of uranium on Uranus, 0:08:02.520 --> 0:08:06.560 seeing that uranium is distributed throughout the universe and um 0:08:06.760 --> 0:08:10.440 maybe concentrated more on rocky planets. But my guess is 0:08:10.480 --> 0:08:13.840 if we look really, really hard, we'd find that one atom. Yeah, 0:08:13.880 --> 0:08:17.000 why not? I guess that's it's a pretty big planet 0:08:17.040 --> 0:08:22.480 and it's mostly gas, but I don't think why there 0:08:22.520 --> 0:08:29.480 shouldn't be any other stuff than what it's made out of, 0:08:30.920 --> 0:08:37.600 because meteors and other things are constantly falling into it, 0:08:37.679 --> 0:08:42.200 and I guess they're bound to be some that consists 0:08:42.280 --> 0:08:48.240 of or have some uranium in them. So yeah, I'm 0:08:48.280 --> 0:08:51.959 pretty confident about that. I would guess yes, because you're 0:08:51.960 --> 0:08:54.560 asking it, but I'm not very confident in that answer. 0:08:54.920 --> 0:08:58.640 I'm gonna guess no. Uranus was named by people who 0:08:58.640 --> 0:09:01.840 did not know what uranium is, but they named it 0:09:01.960 --> 0:09:06.240 after a Greek god in Greek mythology. But what do 0:09:06.280 --> 0:09:10.520 I know? Yeah, I would think so because if I'm 0:09:10.600 --> 0:09:16.120 not mistaken, it's a high pressure environment, and I would 0:09:16.200 --> 0:09:20.480 guess that, you know, heavier elements and radioactive elements like 0:09:20.640 --> 0:09:24.800 uranium would develop in a higher pressure environment like Uranus, 0:09:24.800 --> 0:09:31.000 possibly closer towards the core. If there is any uranium 0:09:31.360 --> 0:09:34.360 on ur I don't think that there would be very 0:09:34.440 --> 0:09:38.760 much of it. There is probably a small amount scattered 0:09:38.760 --> 0:09:46.120 to me amongst the war particles from meteorites or just stardust, 0:09:47.480 --> 0:09:50.120 or maybe it has a rocky core, knows. I think 0:09:50.160 --> 0:09:56.480 it's mostly ice of light liquids, small molecules frozen, so 0:09:56.840 --> 0:09:59.720 it probably has a little. But you know, I think 0:09:59.720 --> 0:10:02.680 that two might be related in namesake only, I would 0:10:02.760 --> 0:10:07.840 say yes, definitely, at least one particle. I don't know. 0:10:08.000 --> 0:10:10.040 I don't think that's what the plan is named for, 0:10:10.640 --> 0:10:13.840 but I don't see a reason why it wouldn't have 0:10:13.920 --> 0:10:16.839 some uranium. Thanks so much for those answers. There were 0:10:16.840 --> 0:10:20.640 some really insightful answers in there. And actually, when Daniel 0:10:20.679 --> 0:10:23.400 proposed this question to me, initially, it made me realize 0:10:23.640 --> 0:10:26.719 that I didn't know how uranus got its name and 0:10:26.760 --> 0:10:29.360 I didn't know the answer to this question. And I 0:10:29.400 --> 0:10:32.559 agreed with some of the listeners. I thought, probably there's 0:10:32.640 --> 0:10:36.160 there's at least some uranium and uranus, because it seems 0:10:36.160 --> 0:10:37.680 like they would sort of have to be like maybe 0:10:37.679 --> 0:10:39.240 if it was in a comment or an asteroid that 0:10:39.320 --> 0:10:41.840 slammed into uranus, even if it wasn't made in there, 0:10:41.880 --> 0:10:44.880 it might show up there. But I actually didn't know 0:10:44.960 --> 0:10:46.439 the answer for sure, So I think I was in 0:10:46.480 --> 0:10:48.920 the same boat as a bunch of these listeners. But 0:10:49.040 --> 0:10:51.080 it turns out that I don't know too much about 0:10:51.280 --> 0:10:54.160 uranus and where it got its name. So can you 0:10:54.200 --> 0:10:56.120 tell us a bit about that, Daniel, Yeah, I love 0:10:56.160 --> 0:10:59.040 this question because it has two really fun science stories, 0:10:59.080 --> 0:11:01.880 the story of Uranus and the story of uranium, and 0:11:01.920 --> 0:11:04.000 then it ties them together. So Urin this is a 0:11:04.080 --> 0:11:08.679 really funny planet because it's history is hilarious, honestly, first 0:11:08.679 --> 0:11:12.120 of all, because it was seen many many times before 0:11:12.200 --> 0:11:15.400 anybody even understood that it was a planet. There's like 0:11:15.520 --> 0:11:19.960 so many missed opportunities to make like a cosmic scale discovery, 0:11:20.040 --> 0:11:23.360 leave your mark on humanity. Even back in like one 0:11:24.240 --> 0:11:27.839 b C. Hipparcos saw it, and there's like recordings of 0:11:27.920 --> 0:11:30.840 people seeing this thing in the sky going back to 0:11:30.880 --> 0:11:34.640 like sixteen ninety or seventeen fifty. People like saw it 0:11:34.920 --> 0:11:38.000 and noted it in their journals, but they didn't realize 0:11:38.040 --> 0:11:40.320 it was a planet for a long time. It still 0:11:40.360 --> 0:11:43.800 blows my mind that people in like the BC era, 0:11:43.960 --> 0:11:46.520 we're looking up at space and had enough of a 0:11:46.679 --> 0:11:49.360 knowledge about like what belonged where that they could notice 0:11:49.400 --> 0:11:52.000 that something new had moved in that like needed to 0:11:52.000 --> 0:11:54.079 be identified or something, Because you know, I still look 0:11:54.160 --> 0:11:55.560 up the night sky and I'm like, oh, that's a 0:11:55.559 --> 0:12:00.120 bunch of stuff up there. Even back then, they were 0:12:00.120 --> 0:12:02.319 doing a much better job than I do at cataloguing 0:12:02.400 --> 0:12:04.800 these things, and I find that very impressive. So what 0:12:04.880 --> 0:12:06.640 did they think that it was? Well, a lot of 0:12:06.640 --> 0:12:08.600 people just thought that it was a star. It's sort 0:12:08.600 --> 0:12:11.760 of dim and slowly moving because it's really far out 0:12:11.840 --> 0:12:14.320 there in the Solar System, and you know, the further 0:12:14.440 --> 0:12:17.360 out you are in the Solar System, the slower you orbit, 0:12:17.559 --> 0:12:20.680 like the actual linear speed is slower because the gravitational 0:12:20.760 --> 0:12:23.640 pull on the planet is less, so you move less rapidly. 0:12:23.760 --> 0:12:26.680 So in our sky urine, this doesn't move very fast. 0:12:27.000 --> 0:12:28.679 So some people just thought it was a star that 0:12:28.720 --> 0:12:30.959 like wandered a little bit because you know, it's sort 0:12:30.960 --> 0:12:33.920 of hard to keep track back in the day about 0:12:33.920 --> 0:12:36.240 what was moving in the sky and what was induced 0:12:36.280 --> 0:12:39.080 by the Earth rotation, etcetera, etcetera, And so for a 0:12:39.080 --> 0:12:41.120 long time people just thought it was a star. And 0:12:41.160 --> 0:12:43.840 then the guy who actually discovered it, a guy named Herschel, 0:12:43.960 --> 0:12:45.520 he saw it in the sky and he thought it 0:12:45.559 --> 0:12:48.360 was a comment at first, so he didn't even realize 0:12:48.559 --> 0:12:50.800 it was a planet. So the guy we give credit 0:12:50.840 --> 0:12:53.240 to for discovering it actually thought it was a comment 0:12:53.320 --> 0:12:55.880 when he saw it and recorded it. Don't comments tend 0:12:55.880 --> 0:12:58.360 to move faster than planets. I guess it's like more 0:12:58.360 --> 0:13:00.920 than two years ago. So calculating this stuff was tough. 0:13:01.000 --> 0:13:02.960 But why did you think it was a commet? Well 0:13:03.000 --> 0:13:06.679 because he did the calculation very carefully, because other people 0:13:06.760 --> 0:13:09.400 looked at his results and his data and they calculated 0:13:09.440 --> 0:13:12.120 the orbit from his data and they're like, no, that's 0:13:12.160 --> 0:13:14.840 not the orbit of a comet. That must be a planet. 0:13:14.880 --> 0:13:16.760 You know what's the difference. The difference is that the 0:13:16.760 --> 0:13:19.199 comet is like very eccentric orbit. A lot of these 0:13:19.240 --> 0:13:22.000 things come from like the Ort cloud, like really far 0:13:22.120 --> 0:13:24.600 out there in the Solar System, and then they exume 0:13:24.840 --> 0:13:27.840 in very close to the Sun before zooming out, whereas 0:13:27.840 --> 0:13:30.600 the planet is like a much larger object that's obviously 0:13:30.800 --> 0:13:34.560 cleared its field and orbits with a much more circular orbit. 0:13:34.600 --> 0:13:37.680 Not perfectly circular, but much more circular. And so it 0:13:37.760 --> 0:13:40.760 was other people who looked at Herschel's data and they 0:13:40.880 --> 0:13:43.120 decided it was a planet, and it was only Herschel 0:13:43.200 --> 0:13:45.719 later being like, oh, okay, yeah, I agree with you. 0:13:46.040 --> 0:13:48.319 What I saw was a planet. So like, I don't 0:13:48.360 --> 0:13:51.800 even know why he gets credit for this? There did 0:13:51.800 --> 0:13:53.480 he get to name it? And so then there was 0:13:53.520 --> 0:13:56.719 like a seventy year argument about how to name it. 0:13:56.760 --> 0:14:00.040 So Herschel wanted to name it George's Star, which is 0:14:00.080 --> 0:14:02.840 like a terrible name because it's not a star, so 0:14:02.880 --> 0:14:04.400 he thought he was a comment. He wanted to name 0:14:04.440 --> 0:14:07.080 it after a star, which makes those sense. Other people 0:14:07.280 --> 0:14:10.560 wanted to name it Neptune because we didn't have Neptune yet, 0:14:10.679 --> 0:14:14.040 or Neptune Great Britain, like even more awkward name if 0:14:14.040 --> 0:14:18.439 you can imagine. And finally somebody else suggested naming Uranus 0:14:18.480 --> 0:14:21.200 after the god of the sky, you know, to follow 0:14:21.240 --> 0:14:24.120 this pattern that were naming the planets after these Greek 0:14:24.160 --> 0:14:26.400 and Roman gods. And so there was a long, like 0:14:26.600 --> 0:14:29.600 seventy year battle about what to call this thing. One 0:14:29.600 --> 0:14:32.160 group of people calling it Uranus, another group of people 0:14:32.400 --> 0:14:36.040 calling it George's Star. And it wasn't until eighteen fifty 0:14:36.080 --> 0:14:39.400 when the British Navy the bureaucracy finally accepted the name 0:14:39.520 --> 0:14:42.680 Uranus that it like formally became Uranus. So it was 0:14:42.720 --> 0:14:45.560 like seventy years when people are arguing about like just 0:14:45.600 --> 0:14:48.040 what to call this thing, So like did they know 0:14:48.160 --> 0:14:50.800 what they were doing at the time, because anatomy was 0:14:50.840 --> 0:14:53.680 pretty far along at that point. Did they realize school 0:14:53.760 --> 0:14:57.720 children would be laughing for generations to come, or had 0:14:57.800 --> 0:15:00.120 had all the body parts not been quite named at 0:15:00.120 --> 0:15:02.720 at that point. That is a great question, and it 0:15:02.800 --> 0:15:05.080 might also have to do with like the evolution of 0:15:05.120 --> 0:15:07.800 the British accent. Right, I don't know what that word 0:15:07.920 --> 0:15:10.200 sounded like a hundred and fifty years ago, or what 0:15:10.320 --> 0:15:12.960 those two words that you have in mind sounded like, 0:15:13.040 --> 0:15:15.120 and if they sounded more or less similar, that's a 0:15:15.120 --> 0:15:18.360 great question. Linguists out there or historians of the British 0:15:18.360 --> 0:15:20.600 accent please write to us and let us know how 0:15:20.640 --> 0:15:23.680 similar those two words sounded over the years. We asked 0:15:23.680 --> 0:15:26.920 the big questions we do. We go all the way 0:15:27.000 --> 0:15:29.600 up there and ask all the big questions. But you know, 0:15:29.640 --> 0:15:32.920 it turns out to be scientifically, are really fascinating planet 0:15:33.000 --> 0:15:35.000 for lots of reasons. One reason is that it's a 0:15:35.040 --> 0:15:39.400 great example of a giant planet that's not a gas giant, 0:15:39.800 --> 0:15:42.600 right like Jupiter and Saturn. We call these planets gas 0:15:42.640 --> 0:15:46.680 giants because they're mostly hydrogen, but Neptune and Uranus we 0:15:46.720 --> 0:15:50.520 call them ice giants because they really are a different composition. 0:15:50.680 --> 0:15:52.640 And is that water ice or is that some other 0:15:52.720 --> 0:15:55.400 kind of ice? So there's a mixture of water, ice 0:15:55.560 --> 0:15:59.480 and ammonia and also methane, and the difference is really 0:15:59.520 --> 0:16:01.960 that sort of like a race to get the gas. 0:16:02.360 --> 0:16:04.760 Like in the formation of the Solar System, you start 0:16:04.800 --> 0:16:07.880 out with a huge blob of stuff which is mostly hydrogen, 0:16:08.120 --> 0:16:09.920 and then you know there's some rock and some water 0:16:10.000 --> 0:16:12.520 and some other stuff, but really by mass, it's almost 0:16:12.520 --> 0:16:15.960 all hydrogen, and almost all of it grabbed by the Sun. 0:16:16.160 --> 0:16:18.600 Right the whole Solar system is formed, because the Sun 0:16:18.680 --> 0:16:22.480 begins this gravitational collapse and because it becomes very quickly 0:16:22.520 --> 0:16:25.280 the densest thing, the heaviest thing, then it grabs all 0:16:25.280 --> 0:16:27.920 the gas. Like hydrogen, gas is very light and so 0:16:28.000 --> 0:16:30.520 gravity pulls on it very effectively. So then to have 0:16:30.640 --> 0:16:33.000 any gas, to accumulate any gas, you have to build 0:16:33.080 --> 0:16:35.960 up enough mass to steal some from the forming Sun, 0:16:36.200 --> 0:16:38.880 and so if you don't get big enough fast enough, 0:16:38.960 --> 0:16:42.040 then you don't really get very much gas. So Jupiter 0:16:42.120 --> 0:16:44.600 and Saturn like past this point where they can sort 0:16:44.640 --> 0:16:46.960 of have a runaway effect and grab some of the 0:16:47.000 --> 0:16:49.200 gas before the Sun got almost all of it. But 0:16:49.360 --> 0:16:52.760 Neptune and Uriness didn't get big enough fast enough, so 0:16:52.800 --> 0:16:55.400 they just ended up like a blob of ice and rock. 0:16:55.640 --> 0:16:57.760 So like the Moon and Mars didn't get most of 0:16:57.800 --> 0:17:01.080 those gas either, and then Earth got theres from getting 0:17:01.120 --> 0:17:03.640 collided with stuff. Yeah, and we have a whole fun 0:17:03.640 --> 0:17:06.080 episode about how the Earth got its atmosphere. It had 0:17:06.119 --> 0:17:08.240 a little bit of gas in the beginning, but then 0:17:08.280 --> 0:17:11.120 it was mostly stolen away by the Sun and blown off, 0:17:11.160 --> 0:17:14.520 and then it later recreated its atmosphere from volcanoes and 0:17:14.560 --> 0:17:17.320 commentary collisions. It's an incredible story. And that's one of 0:17:17.359 --> 0:17:19.399 the things I love about these questions is that it 0:17:19.440 --> 0:17:22.520 tells you the rich, rich history of the Solar System. 0:17:22.720 --> 0:17:25.159 It's not just like, oh, the planets formed and then 0:17:25.160 --> 0:17:27.520 they were zooming around for four and a half billion years. 0:17:27.560 --> 0:17:31.479 Like there are twists and turns and new characters and 0:17:31.520 --> 0:17:34.639 like lost characters, and probably planets that existed in the 0:17:34.640 --> 0:17:36.920 Solar System for millions or billions of years which are 0:17:36.920 --> 0:17:39.840 now lost because they've been thrown out when Jupiter went 0:17:39.920 --> 0:17:43.159 like in and then out again. It's a crazy story. 0:17:43.240 --> 0:17:45.560 It's like a soap opera, and it's amazing we've figured 0:17:45.600 --> 0:17:49.320 any of it out. So Urinest didn't managed to grab 0:17:49.359 --> 0:17:51.600 this stuff and then it didn't have the like help 0:17:51.720 --> 0:17:54.399 that Earth had to get it with all of that 0:17:54.440 --> 0:17:56.000 other stuff, and so that's how it ended up with 0:17:56.040 --> 0:17:58.080 not a lot of gas, that's right, And so we 0:17:58.119 --> 0:18:01.280 don't actually know that much about what's in Urinus. We 0:18:01.320 --> 0:18:04.760 have a model roughly for what it looks like, but 0:18:04.840 --> 0:18:07.320 it's important to realize that we haven't really studied it 0:18:07.440 --> 0:18:09.720 very much. We've looked at it with telescopes. We sent 0:18:09.920 --> 0:18:12.480 one probe by it voyage or two, but that's really 0:18:12.560 --> 0:18:16.199 the only close flyby of Uranus we've ever had. And 0:18:16.240 --> 0:18:18.480 so we have a model for what's going on inside it, 0:18:18.520 --> 0:18:22.160 which comes mostly from these models of solar system formation, 0:18:22.240 --> 0:18:24.480 like what do we think had time to get in there? 0:18:24.680 --> 0:18:27.879 And that model looks like a rocky core, so like 0:18:28.040 --> 0:18:31.320 basically a huge rock about like half of the mass 0:18:31.320 --> 0:18:33.439 of the Earth, and that's at the very center of it, 0:18:33.480 --> 0:18:36.160 and then it's surrounded most of the mass of urine. 0:18:36.160 --> 0:18:39.200 Is is this icy mantle and you know, we say ice, 0:18:39.240 --> 0:18:43.360 but it's mostly like a big water ammonia ocean. It's 0:18:43.400 --> 0:18:45.920 like liquid or it's or it's fluid. At least it's 0:18:46.000 --> 0:18:48.520 under a lot of pressure, so it can still move 0:18:48.600 --> 0:18:51.280 and flow. So do the way the Earth's mantle can, 0:18:51.400 --> 0:18:54.000 but you wouldn't say necessarily that it's liquid. So I 0:18:54.040 --> 0:18:55.960 think I'm getting confused yet. So so we you know, 0:18:55.960 --> 0:18:57.960 when we were talking about it not picking up a 0:18:57.960 --> 0:18:59.919 bunch of stuff, where did all this water in them 0:19:00.000 --> 0:19:01.680 when you come from? Was? Was that just stuff it 0:19:01.720 --> 0:19:04.359 got lucky to grab initially or did it come somewhere 0:19:04.359 --> 0:19:06.240 else from Earth? I feel like I already asked this question, 0:19:06.320 --> 0:19:08.919 but now I'm confused about where all this water came from. Right, 0:19:08.920 --> 0:19:11.639 So there's a huge amount of water and ice and 0:19:11.680 --> 0:19:14.800 ammonia in the Solar system. So the initial formation of 0:19:14.800 --> 0:19:17.400 the Solar system, you have this cloud of hydrogen. Most 0:19:17.400 --> 0:19:20.159 of the hydrogen went to the gas giants, but the 0:19:20.240 --> 0:19:22.360 other stuff is heavier, it's slower, and so it's sort 0:19:22.400 --> 0:19:25.600 of more likely to accumulate where it was initially. And 0:19:25.640 --> 0:19:27.840 this stuff is far enough out from the Sun that 0:19:27.920 --> 0:19:30.880 it stays frozen, so like the water is an ice 0:19:30.960 --> 0:19:33.480 form and the ammonia is frozen. And so all of 0:19:33.480 --> 0:19:36.080 this stuff that formed Urineus and Neptune and that was 0:19:36.119 --> 0:19:37.919 the stuff that was sort of in the outskirts of 0:19:37.960 --> 0:19:41.119 the Solar system originally, and then just sort of like coalesced. Like. 0:19:41.240 --> 0:19:44.040 Even further out in the Solar System is the Earth Cloud, 0:19:44.080 --> 0:19:47.760 which is a bunch more frozen objects that become comets, 0:19:47.760 --> 0:19:50.639 and those are also just balls of ice. So everything 0:19:50.640 --> 0:19:53.000 that's really really far out in the Solar System is 0:19:53.000 --> 0:19:55.359 basically just rock and ice at this point, and it 0:19:55.400 --> 0:19:58.840 pulls together to form these ice giant planets. I'm with 0:19:58.880 --> 0:20:00.880 you now. So the core of it is this big rock, 0:20:01.080 --> 0:20:04.719 and then outside of that, like thirteen masses of the Earth, 0:20:05.280 --> 0:20:08.560 is this hot, dense fluid. It's not frozen, right, It's 0:20:08.600 --> 0:20:11.600 called ice, but it's not frozen. It's it's very confusing, 0:20:11.760 --> 0:20:14.680 so it's sort of like an ocean. It's more like liquid, 0:20:14.760 --> 0:20:17.920 but it's not technically in that phase. So chemists out 0:20:17.920 --> 0:20:20.080 there would be particular about how this is referred to, 0:20:20.280 --> 0:20:23.000 but they do definitely call it an ice, and that's 0:20:23.000 --> 0:20:26.040 what most of Urinus is. And then outside of that, 0:20:26.080 --> 0:20:29.000 there's like an envelope. There's an atmosphere that's like another 0:20:29.080 --> 0:20:31.160 half the mass of the Earth, and that has some 0:20:31.280 --> 0:20:33.639 hydrogen and some other gases in it. That's sort of 0:20:33.640 --> 0:20:36.560 like the triple layers of Uranus. So I watch a 0:20:36.600 --> 0:20:39.040 bunch of kids shows with my kids, and I feel 0:20:39.040 --> 0:20:41.400 like the one fact about Urinus that we always hear 0:20:41.640 --> 0:20:44.080 is that it rotates on its side. Do we know 0:20:44.680 --> 0:20:47.960 why it's rotated? Why all those layers are rotating the 0:20:48.000 --> 0:20:50.520 wrong way? Did it get hit by something and sort 0:20:50.560 --> 0:20:54.520 of knocked off kilter. It's super cool that it's doing that, because, 0:20:54.560 --> 0:20:57.720 as you say, it's evidence that something happened, And the 0:20:57.760 --> 0:21:00.399 reason it has to be evidence that something happened is 0:21:00.440 --> 0:21:03.600 that we're pretty sure a planet can't just naturally form 0:21:03.680 --> 0:21:06.560 that way. You notice that, like all the planets are 0:21:06.640 --> 0:21:08.600 sort of in the same plane. That's the plane we 0:21:08.640 --> 0:21:11.879 call the ecliptic, and it's also very well aligned with 0:21:11.880 --> 0:21:15.199 how the Sun rotates, So the Sun is spinning as well. Right, 0:21:15.240 --> 0:21:16.800 it's not just sitting there in the center of the 0:21:16.840 --> 0:21:19.879