Cosmic Queries – Space Volcanoes: Fire and Ice with Natalie Starkey

What’s a supervolcano? On this episode, Neil deGrasse Tyson and comic co-host Matt Kirshen discover all types of volcanoes in the solar system with cosmochemist and author of Fire and Ice, Natalie Starkey. Is there such a thing as an ice volcano?

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 0:14Neil deGrasse Tyson?

  This is StarTalk. Yuliel deGrasse Tyson here, your personal astrophysicist. We're gonna do another Cosmic Queries edition. These are becoming so much the favorite of our listening and viewing audience. And today, we're gonna do Fire and Ice. Ooh, I love it. It's literary, it's scientific, and we'll get into it in just a moment. First, my co-host for this episode, Matt Kirshen. Matt, welcome back.

• 0:42Matt Kirshen?

  Hey, how's it going?

• 0:43Neil deGrasse Tyson?

  Matt, I love it when comedians are into science. You've got your own podcast called Probably Science? I think I get it right.

• 0:51Matt Kirshen?

  That is it?

• 0:52Neil deGrasse Tyson?

  I'm two for two. I did it last time, and I got it right.

• 0:54Matt Kirshen?

  Two in a row. I'm loving this. Yeah, the probably is in there for good reason. I would say I...

• 1:00Neil deGrasse Tyson?

  Don't undersell what you got going there.

• 1:02Matt Kirshen?

  That's true. I like being described as a comedian that's into science and not a failed math student who fell backwards into comedy.

• 1:11Neil deGrasse Tyson?

  Even though that is exactly, actually, what happened there.

• 1:13Matt Kirshen?

  Which is exactly what happened.

• 1:15Neil deGrasse Tyson?

  So that means you do have math fluency. That's always good. Can't hurt...

• 1:19Matt Kirshen?

  I did at one point, yeah.

• 1:20Neil deGrasse Tyson?

  Well, always, always good to have you, have you back. And today, Fire and Ice. I'd love the literary reference that that makes, just, you know, it just, it just makes you wonder, you know, what's, what's, is it good? Is it bad? And we have someone who's like an expert on the fire and ice of the solar system, and that is Natalie Starkey. Natalie, welcome back.

• 1:44Natalie Starkey?

  Hi, it's so good to be here.

• 1:46Neil deGrasse Tyson?

  Not your first StarTalk rodeo.

• 1:48Natalie Starkey?

  Not at all, no.

• 1:50Neil deGrasse Tyson?

  Yeah, it's excellent, excellent. You're coming to us from... From the UK. And let me get your official title, you're Public Engagement Officer at the Open University, which is an institution just outside of London, and you're a science communicator. That's just a beautiful thing, because we need more of that. Can we clone you? You'll be the first in line.

• 2:12Natalie Starkey?

  Do you know what? There's loads of us. There's so many of us out there, and it's amazing, you know, when I'm in this field.

• 2:17Neil deGrasse Tyson?

  Yes.

• 2:17Natalie Starkey?

  All these other practitioners, there's so many of us.

• 2:20Neil deGrasse Tyson?

  We can call it a field, right?

• 2:22Natalie Starkey?

  Yeah, exactly.

• 2:23Neil deGrasse Tyson?

  A place to be, a place to be. You're a geologist, and you specialize in volcanoes? Is that?

• 2:29Natalie Starkey?

  I did, yeah, yeah, back, you know, it feels like it's decades ago now, but I started out as a geologist because I was fascinated by volcanoes.

• 2:38Neil deGrasse Tyson?

  I'm just wondering, how do you, if you're a geologist at all, how could you not be fascinated by volcanoes? Because that's.

• 2:44Natalie Starkey?

  Well, exactly.

• 2:45Neil deGrasse Tyson?

  That reshapes your planet, right?

• 2:46Natalie Starkey?

  Exactly. I think the thing for me was that I didn't even really know what geology was when I was at school, because you don't really do it as a core subject. And then I learnt about volcanoes and was fascinated, and I read this amazing book called Surviving Galeras by this volcanologist called Stanley Williams, and it was his story about how he'd gone up this volcano and it had unexpectedly erupted, and he'd taken all these people with him and ended up in these dire circumstances, and lots of people got killed and injured, and for some reason, that really inspired me to study volcanoes. And I was like, well, I don't know why, because I don't consider myself a risk taker, but I just really was fascinated by them, and I then learned that actually I needed to do geology to.

• 3:26Neil deGrasse Tyson?

  So the fact that volcanoes can kill you earned a certain level of respect.

• 3:30Natalie Starkey?

  Yeah, completely.

• 3:31Neil deGrasse Tyson?

  Personally, emotionally, and professionally. And just to be clear, Matt, in case you didn't know, a volcanologist, it's not about Spock or anything from Star Trek. Just want to make that one clear.

• 3:44Matt Kirshen?

  But am I right in thinking that you also thought in your career that volcanoes on Earth are just a little bit too dull?

• 3:52Natalie Starkey?

  Well, you know, there's always that because we know so much about them. No, it's not. It's not true. I mean, the thing is with my book, I've dedicated, you know, almost half the book to the volcanoes on Earth because we know them.

• 4:01Neil deGrasse Tyson?

  Well, I didn't mention that yet. You have a book called Fire and Ice.

• 4:04Natalie Starkey?

  I do. Oh, Sandy. I know. I don't know how I got that in there.

• 4:07Neil deGrasse Tyson?

  Yeah, yeah, yeah. You're supposed to let me talk about your book, not you talk about your book. Uh, Fire and Ice, it's a great title. And, um, is it, you, like, as Matt's saying, you were not content with just volcanoes on Earth.

• 4:21Natalie Starkey?

  No, no, not at all. Because after I did my geology degrees, I moved into space science. So I was basically doing chemistry on volcanic rocks to understand how the Earth formed. That was kind of my PhD thesis. And then I discovered that actually you could do the same chemistry on rocks from space. So that led me to analyzing pieces of comets and asteroids brought back by space missions. And so it kind of broadened my horizons. I'd never really thought about studying anything from space before. I never thought that was really an option for me. But then suddenly I'm combining all of these expertise. And so it kind of led on after my first book, which was about comets and asteroids, and I wrote all about those first. Then I was like, hold on, I'm going to combine this all and write about volcanoes in space because it just seemed like the natural thing to do.

• 5:05Neil deGrasse Tyson?

  And, and let, let the world know, if they didn't already, that you wrote the current space show at the Hayden Planetarium called Worlds Beyond Earth. So thanks for, thanks for agreeing to do that and, and bringing some of your expertise across the pond, as we say, of the Atlantic Ocean. And we were delighted to collaborate with you on that. So thanks for bringing that collective expertise. If you were just a geologist, no, we wouldn't have had you.

• 5:35Natalie Starkey?

  Yeah, thank goodness. Okay.

• 5:36Neil deGrasse Tyson?

  We needed that space dimension that you brought to the table.

• 5:40Natalie Starkey?

  And that was such a fun show to write. Oh, my goodness. I learned so much in the process as well, like having to combine, you know, that kind of scientific expertise with, you know, basically space artists, people that can, you know, image this stuff that we write about and we talk about so much, and using all that kind of real data from NASA and ESA missions and, and using it to create this beautiful show. It was, yeah, it was a great experience.

• 6:02Neil deGrasse Tyson?

  Yeah, all your words on the page are actually happening visually on the dome. Yes, yes, yeah. And, and so, so I'm curious about something. Um, is there a Um, you know, when we think of volcanoes, we think of hot things. And so why is the word ice in your title?

• 6:22Natalie Starkey?

  Yeah, good question. Okay, so a lot of people don't realize that actually most of the volcanoes out in the solar system, particularly when we go past the asteroid belt out to Jupiter and beyond. Most of the bodies out there are actually ice volcanoes. So these are, these are active places.

• 6:36Neil deGrasse Tyson?

  Wait, wait, wait, wait, wait. You're speaking like, okay, yeah, most of the volcanoes in the solar, yeah, yeah, that's cool. Like, do people even know we have volcanoes other places than Earth?

• 6:49Natalie Starkey?

  Oh, I'm sure they do.

• 6:51Neil deGrasse Tyson?

  Really?

• 6:51Natalie Starkey?

  I'm sure they do. So most people have heard of Olympus.

• 6:54Matt Kirshen?

  I don't know. I would, I would say maybe a fair proportion, a large proportion of the listeners of this show would know it. But I think if you polled the average person on the street, I don't know if you would necessarily think of a volcano as being on other planets. I don't know if you'd even necessarily think of.

• 7:08Neil deGrasse Tyson?

  Maybe I've spoken to too many flat earthers. If people think Earth is flat, they're not thinking that there are volcanoes elsewhere. So I just have issues with believing that this is widespread.

• 7:17Matt Kirshen?

  But even, e- even people who have, you know, who have a- accept as broad acceptance of science, but maybe answers as embedded in it. I, I would even say, and this is, this is even something, it's, obviously I know that the heat from volcanoes and the molten rock isn't fire in per se, but the idea of something that looks like fire coming in a vacuum in places that don't have air, that seems strange.

• 7:42Neil deGrasse Tyson?

  So all of this, okay, so we have fire in vacuum and we have ice in volcanoes. So explain yourself, Natalie.

• 7:49Natalie Starkey?

  Yeah, so I mean, I use fire, you know, to kind of just represent the fire-ness of volcanoes. And it's something I go into in, in the book a lot, but we can also use it to represent, you know, there are lots of fiery volcanoes out in the solar system. We, we had active worlds around us. Mars was massively active kind of three billion years ago. Venus, our next door neighbor, is probably still active today. It's probably got volcanoes erupting today, we think, but we just can't see them happening. But there's a lot of evidence that it probably is happening.

• 8:19Neil deGrasse Tyson?

  But why can't we see them?

• 8:20Natalie Starkey?

  Well, there's lots of issues with Venus. It's not a very nice place, basically. It's really hard to see. It's covered in this shroud of gas, basically, of carbon dioxide, which means, so its atmosphere is really, really thick and dense, so it's really hard to see through it. You can't see through it with visible light. You need like a radar to see through it, which we've done. We've sent spacecraft up to look through that really dense atmosphere and we looked at the surface of Venus and we can see it's just covered in lava flows. So everything that's on its surface is basically basalt, which is the same kind of stuff that we find in places like Hawaii and Iceland, very, very standard volcanic rock that we see a lot on our own planet. But the whole of Venus is about the same age. It looks like it's about 500 million years old, which sounds really old, but actually in kind of

• 9:04Natalie Starkey?

  the age of the solar system, that's not very old. It's been active quite recently.

• 9:09Neil deGrasse Tyson?

  And just to be clear, you called Venus our neighbour, but Mars is our neighbour too.

• 9:12Natalie Starkey?

  Yeah, so the thing about Venus is that it's a similar size. Yeah, it's just, the important thing is it's a similar size to Earth and it was made of the very same ingredients as were all the terrestrial planets, all the ones within the inner solar system. So it should be very similar to Earth. Like, we should expect it to be very similar to our own planet, but it's not for some reason. It's turned into this hellhole. It's, you know, got a surface temperature of 450 degrees Celsius, hot enough to melt lead, it's got horrible pressure on the surface. So, you know, the Soviets sent spacecraft to land there decades ago and these spacecraft lasted just a few hours on the surface before just being crushed to death. So it's not a place we're going to be sending humans anytime

• 9:55Natalie Starkey?

  soon. But it's a fascinating world because what we want to do is understand why it's ended up so different to Earth. Like, why hasn't it got oceans on its surface? And that's one of the big questions that we're actually trying to look at now. We're sending some missions there. NASA are going to send two missions there in the next decade. ESA are going to send one mission. I think the Indians have another mission going.

• 10:14Neil deGrasse Tyson?

  ESA, the European Space Agency, yeah.

• 10:16Natalie Starkey?

  Correct, yeah. And so we're going to find so much about Venus now. So it was Mars. I feel like Mars has had its day now. Like, we've done it. No, we haven't. There's lots still to find out about Mars, but Venus is going to be the next planet we're really going to delve.

• 10:28Neil deGrasse Tyson?

  And just a shout out to India, who's joining the fray there with sending probes to planets, so.

• 10:35Natalie Starkey?

  Yeah, they've done some amazing work. They're, you know, their space agency is doing great. So there's going to be so much information coming back. It's really exciting.

• 10:42Neil deGrasse Tyson?

  Okay, so now where does ice fit into this?

• 10:44Natalie Starkey?

  Oh, yeah. I went off on a tangent, as I said, but yeah.

• 10:49Natalie Starkey?

  The ice part is going to represent all those volcanoes that are past the asteroid belt. So we've got basically a lot of moons around these giant planets out in the outer solar system. So we take Jupiter, Saturn, Uranus and Neptune. They've all got lots of moons around them, like Jupiter has about seventy nine moons that we've found so far. So it's just loads of them, you know, we just, we've just got one. And I'm like, okay, Jupiter's kind of greedy, but it is a big planet.

• 11:13Neil deGrasse Tyson?

  Aren't many of those moons kind of lame excuses for moons?

• 11:17Natalie Starkey?

  No, not at all. I was saying, ours is a bit lame now. Now I've learnt about all these other ones, like.

• 11:23Neil deGrasse Tyson?

  I meant just in terms of how tiny they are.

• 11:25Natalie Starkey?

  No, no, no, not at all. So our, you know, some of the moons out there are actually as big as Mercury.

• 11:31Neil deGrasse Tyson?

  No, I meant among the seventy nine moons of Jupiter, some of them.

• 11:33Natalie Starkey?

  Some of them are not, you know, potentially so interesting. But if we take the Galilean moons, we've got, you know, Io, we've got Ganymede, Europa. These are all really cool places. Io is, is hot. It's very much like Earth was kind of four billion years ago. It's the most volcanically active object in the solar system. So it erupts these plumes of rock almost continuously off its surface. In fact, every space mission that's gone by has seen it erupting. Um, but then all the other moons there are kind of icy moons. So they've got these rocky interiors, but then they're either ocean worlds with an ice cap on the outside or they're just made of ice. Um, and these are the really interesting ones because in order to have sort of an ocean underneath the ice, we know that they must still be warm inside.

• 12:18Natalie Starkey?

  That rocky interior must still be warm somehow. It must be warm enough to heat the ice to turn it into a liquid. Um, and so this instantly tells us that these worlds are active and interesting places to go. And sure enough, the more we've looked, the more we've discovered that they have volcanoes on the surface. So they have plumes of material shooting out from their oceans, which shows us that there's a lot going on beneath the surface.

• 12:42Neil deGrasse Tyson?

  So we can call those ice volcanoes, I guess, is that right?

• 12:44Natalie Starkey?

  Yep, so they're all, the ice volcanoes are like cryovolcanoes, cryo being the cold part. So, and there's loads of them, they're everywhere, they're everywhere we look. So actually, it's almost like the ice volcanoes are more common than the kind of the hot ones that we see in the inner solar system.

• 12:59Neil deGrasse Tyson?

  So your book is like long overdue. Somebody should have been talking about this long ago. It should be like in all the classes.

• 13:05Natalie Starkey?

  Well, this is the thing, it's quite, it's always quite recent that we've really learnt about all of these places. In fact, you know, the Voyager missions went out in the kind of nineteen seventies and eighties. And before that, we had no idea that these places were active. In fact, we didn't even know some of these moons existed. And as we got out there and we started to photograph them, we were then very surprised by the results. So I was at school during that time. And of course, that was, you know, cutting edge research happening at the time. That's not going to be in the school curriculum. So it takes a while for that to kind of filter down. But what we then discovered was that actually some of the data that Voyager got, we didn't see some of this stuff at the time. So it needed kind of reprocessing. So we go back with other missions later and we spy this plume shooting off the surface

• 13:51Natalie Starkey?

  of Enceladus or somewhere. Then we can go back to earlier data that is still sitting in the archives and reprocess it and go, oh, look, we would have seen it there if we'd looked more carefully. We now have loads of evidence that these things have been active for decades. So really, it just takes incremental steps of missions going out and discovering this stuff. But we've barely been out to the outer solar system many times. Like, we've been there just, you know, a handful of missions. So there's still a lot of work to do.

• 14:16Neil deGrasse Tyson?

  Plus, there's an interesting fact that if you do flybys, you just have these snapshots of a moment in time.

• 14:21Natalie Starkey?

  Yeah.

• 14:22Neil deGrasse Tyson?

  Where you then have to generalize what the thing is doing all the rest of the time, which could be very hard. Like, I'm trying to think if an alien flew by Earth and I just happened to be in the bathroom when that happened. You generalize my whole life, oh, he lives in the bathroom. Like, you need at least another data point or something. To capture that. Matt, did you collect questions for us for today?

• 14:45Matt Kirshen?

  We've got a bunch of questions from Patreon patrons who've messaged in.

• 14:49Neil deGrasse Tyson?

  I just have to announce you also have a Brit accent here. I'm surrounded by Brits.

• 14:53Matt Kirshen?

  I do, yeah. When I go back to London now, I get called the American because my accent has imperceptibly changed to American is, but as far as Brits are concerned now, I might as well be from Texas.

• 15:07Natalie Starkey?

  I can definitely hear a twang in there. I think it's somewhere in the middle of the Atlantic at the moment.

• 15:11Neil deGrasse Tyson?

  Oh, yeah, it hasn't fully crossed one way or the other, but it's dangling there. All right, what question, Gig? What do you have for us?

• 15:17Matt Kirshen?

  Well, also, I think you've sort of half answered this already, but I just want to pin down this question from Adam Smith, just to kick things off, because he says, "Is there such a thing as cold volcanoes or ice volcanoes? I imagine ice being spat out like in the way Mr. Freeze did in the 1997 Batman and Robin film, character played by Arnold Schwarzenegger, or is this illogical due to pressure causing heat?" I mostly wanted to ask that question because of how detailed he went in with the specificity of the film.

• 15:46Neil deGrasse Tyson?

  Okay.

• 15:47Matt Kirshen?

  He needed us to know exactly which iteration of Batman and Mr. Freeze he was talking about.

• 15:50Neil deGrasse Tyson?

  Yeah, because you don't want to get confused with some other rendering and play by a different character. Actually, we got to take a quick break, but when we come back, we're going to get Natalie to explain to us how an ice volcano actually works, because that's a mystery to all of us here when we come back on StarTalk.

• 16:20Speaker 03

  Hi, I'm Chris Cohen from Hallworth, New Jersey, and I support StarTalk on Patreon. Please enjoy this episode of StarTalk Radio with your and my favorite personal astrophysicist, Neil deGrasse Tyson.

• 16:46Neil deGrasse Tyson?

  We're back. StarTalk Cosmic Queries, Fire and Ice. I've got Natalie Starkey. There's a book with that title, geologist turned astro person. What she worked on became interesting when she stepped out into space. That happens whatever you're doing on Earth. If you add space to it, it's more interesting. That's my bias. I bet that's your bias too now Natalie, isn't it?

• 17:12Natalie Starkey?

  Yeah, definitely.

• 17:14Neil deGrasse Tyson?

  Okay, there you go. All right, Matt, you left off with a question about Arnold Schwarzenegger, was it?

• 17:20Matt Kirshen?

  Yes, this is from Adam Smith, who is one of the many Patreon patrons whose questions we're answering today. And there's a lot of Batman-specific parts to the question, but the main part is, what is the deal with ice volcanoes? And does ice get spat out from these volcanoes? Or is this illogical due to pressure-causing heat?

• 17:41Neil deGrasse Tyson?

  Yeah, because pressure, whether or not pressure even causes heat, pressure wouldn't have to cause heat. It just has to be pressure, right? I mean, if something gets spewed out of a volcano, it doesn't have to be heat that does it. Is that right?

• 17:52Natalie Starkey?

  So, no, yeah, this is kind of a tricky one to answer. It's a great question for that reason. But basically, there's lots of different ways that volcanoes can erupt. And I think what we need to get away from is thinking, having to think of a volcano as a conical-shaped mountain like we see on Earth. Because actually, when we go out into space, we don't need that. We don't need a conical-shaped mountain to have a volcano. Because we have to just define better what a volcano is. We're sort of skewed towards what we have on Earth, because that's where we first studied volcanoes. So we think they have to look a certain way. But we go out into the solar system, and we look at these other objects around us, and we start going, okay, well, this is a volcano. This is material coming out from the inside of this world, and it's spewing out onto the surface. And

• 18:37Natalie Starkey?

  that's happening because there's heat with inside that world, and it's producing molten material or gas, and it's forcing it, ejecting it out. And that is basically a volcanic type of activity. So we see this at Enceladus. Basically, what's happening? Happening there is that there is heat generated within that world because as Enceladus goes about its orbit around Saturn, it's sort of pulled and pushed on the inside by the gravity of Saturn. So it kind of gets a bit closer, a bit further away from Saturn. And so it's called tidal heating. It's very much like we get with the Earth and the moon, um, that we kind of squash slightly and our tides move. But within Enceladus, for example, they actually the insides of it are squashed. So it's rock creates friction and heat.

• 19:18Natalie Starkey?

  And that then heats the ocean above it and eventually kind of opens cracks in the surface that then allow material to escape. So you'll see it as a plume. That material ends up raining back down onto the surface of Enceladus and, you know, resurfacing that body. But not only that, but these are kind of, what we're actually spewing out is basically gases, ice particles, little pieces of silica grains which come from the very bottom of that ocean. And some of these ice particles actually start to make Saturn's E-ring. So they get sent so high up into space that that is the reason we have Saturn's E-ring within which Enceladus kind of orbits. So that's, yeah, a much longer answer. And that's only one way that we can kind of make volcanoes on these bodies. But

• 20:03Natalie Starkey?

  yeah, in a, in a way, I kind of think that's like the Mr. Freeze character that we're spewing out ice particles into space. And that's by sampling those, which we did with the Cassini mission, um, we know where they're coming from because they're salty. We know they're from a salty liquid ocean below the crust. Um, so that's really cool.

• 20:19Neil deGrasse Tyson?

  Well, so, so if there were fish there, could fish be spewed out too? You get a fish in the E-ring?

• 20:24Natalie Starkey?

  Yeah, exactly. I love this. Now then we need to go back because.

• 20:29Neil deGrasse Tyson?

  I was just kidding. You're telling.

• 20:31Natalie Starkey?

  No, it's like, well.

• 20:32Matt Kirshen?

  Living things could be shot out.

• 20:34Natalie Starkey?

  Anything could. So whatever's down there is going to come out in these plumes. Now, the thing is, when Cassini went, it didn't know it needed to measure this stuff that was coming out in the plumes because we didn't know they were happening. So this is one of these things with space missions. We then learn stuff and we go, ah, we need another mission. We need to go back. And specifically look at these plumes and the material that's in them. What we do know is that there's all the right materials for organic content being there. So we know that there's chemical reactions happening within that ocean that can create organic molecules. Now, it's a step then to say, okay, we need to find life, but there's every chance that it could be down there. It's got all the right conditions for life to form. Okay, not human-like life, but other kinds of life that we might find at the bottom

• 21:16Natalie Starkey?

  of Earth's oceans, for example, which is going to be a very similar environment. So, yeah, every chance, we need to get down there and have a look, basically.

• 21:23Neil deGrasse Tyson?

  So it must be hard enough for a fish in an Earth ocean to be caught, you know, with a line and then thrown back and have to explain to other fish what they saw. That's gotta be hard enough. And now we're gonna have a fish spewed into orbit around Saturn when they were happily swimming beneath the ice.

• 21:45Matt Kirshen?

  Yeah, just be sort of orbiting around the fish on the ground. It's like, get back, get back, get back here.

• 21:52Neil deGrasse Tyson?

  Crazy, crazy.

• 21:53Matt Kirshen?

  Stop messing around.

• 21:55Neil deGrasse Tyson?

  All right.

• 21:56Matt Kirshen?

  Justify yourself.

• 21:56Neil deGrasse Tyson?

  So there you go. All right. So Matt, what more do you have?

• 21:59Matt Kirshen?

  That's a great, that was a great question. My biggest takeaway from your answer there is that the Batman and Robin film was scientifically accurate. So that's nice to know. I like the, I always love it when a question comes from the children of listeners. I like the idea that there's some young kids who are interested in this stuff. So this is from Wes Denham's seven-year-old son Silas, who asks, what is the process that magma goes through to be able to rise to the surface before it explodes?

• 22:25Natalie Starkey?

  Oh my goodness, what a question. That's amazing. I always have the ones from the kids because they're always the hardest to answer. You're like, oh, it's, you know, everyone's like, oh, it'll be a really simple question. Like, no, that's not simple to answer.

• 22:37Neil deGrasse Tyson?

  But just to be clear, what you call magma, we call lava, is that right?

• 22:43Natalie Starkey?

  So, yeah, basically magma is before it's erupted. So below the surface, if we have molten rock, it will be called magma. As soon as it goes above the surface and's erupted out of a volcano, it becomes a lava. Now-

• 22:55Neil deGrasse Tyson?

  Even though it's the same stuff, we just have a different word for it.

• 22:57Natalie Starkey?

  Exactly the same stuff.

• 22:58Neil deGrasse Tyson?

  And then after it hardens, then you call it basalt.

• 23:03Natalie Starkey?

  Well, it's, yeah, it will be a basaltic lava and then when it hardens, it's a, yeah, it's a basaltic rock or basalt, yeah.

• 23:10Neil deGrasse Tyson?

  You geologist, damn, darn you.

• 23:12Natalie Starkey?

  I know, I know, you just like to make life complicated.

• 23:14Neil deGrasse Tyson?

  Okay, okay, so, okay, so now let's, and who's, who asked this question again, Matt? This is young Silas, seven-year-old Silas. Seven, oh my gosh, okay.

• 23:22Natalie Starkey?

  Yeah. When we go to the outer solar system and go to these icy worlds, remember our, our view of volcanoes is skewed towards what we have on Earth, so we think volcanoes need to be rocky and then we go out there and go, oh no, they don't, they can be icy. So, basically, when we talk about magma or lava on, for example, Pluto, let's take Pluto because that's a great example, um, it's not rocky, the stuff that Pluto is made of is all ice. So when we talk about Pluto's magma, it's basically just the molten version of whatever it's made of. Its bedrock is water, ice, and ammonia, and methane, and nitrogen. So when we melt those materials, which it's easier to do because they, they have lower melting points, um, we basically make magma or lava of those materials.

• 24:07Natalie Starkey?

  So that's, that's their magma, that's their lava. So it just depends where you are, we just need to center ourselves on the right world. So whatever happens, basically, you need to heat the stuff. So if you've got rock within the side of planets, which we do, if you delve down into our planet, it's hard and it's rocky, um, we need to melt that stuff in order to make it rise. As soon as you make a liquid of, of a solid thing, then it's more buoyant and it just wants to naturally rise through that body. So that's generally what happens. Now, the other thing with magmas is that they often contain a lot of gases, um, and these gases just want to escape, so they kind of overpressure this magma as it rises up and that causes it to just keep rising and keep rising and melting its way through the crust until it gets to the surface.

• 24:48Natalie Starkey?

  Um, and then, basically, what happens is those gases want to just erupt out of that lava very quickly and that's generally what makes the explosion at the surface, if we see something, you know, like mountains and helms or somewhere. That was just that magma basically exploding as it got to the surface and blowing that mountain apart, um, as that pressure is released when you get to that normal.

• 25:07Neil deGrasse Tyson?

  Wait, wait, so if the explosion blows a mountain apart, how do we get the mountain in the first place?

• 25:11Natalie Starkey?

  So the mountain initially was built up from very like continuous eruptions of lava and ash. And so we call these strato-volcanoes. And so they generally build up quite slowly over years and years and then, you know, trees grow on them. And they look just like a mountain and we don't think they're scary. And this is partly why volcanoes are very dangerous, because they don't.

• 25:31Neil deGrasse Tyson?

  Like Map Fuji has a very nice shape, very beautiful shape.

• 25:34Natalie Starkey?

  Oh, it's beautiful, yeah. You know, I loved with the Olympics coverage this year.

• 25:37Neil deGrasse Tyson?

  Yes, it was gorgeous.

• 25:37Natalie Starkey?

  Beautiful, they use that image all the time, Snowcat Mountain. And I think that's.

• 25:43Neil deGrasse Tyson?

  It's the volcano that looks most like a child's drawing. Yes.

• 25:45Natalie Starkey?

  Exactly.

• 25:46Neil deGrasse Tyson?

  It doesn't even look real, right? It's like, yeah.

• 25:49Natalie Starkey?

  It's beautiful and I think that's why we we sort of forget as humans, because these, you know, volcanoes can erupt not very often, but they're still classed as active. So 10,000 years is usually the timeframe where we say, if it hasn't erupted for 10,000 years, then it it might be not active any longer. But the problem is, we don't as humans remember that kind of timeframe. So people live close to volcanoes for many different reasons. And the the land around volcanoes is often very fertile, so it's really good to make crops and everything and grow stuff. And also the land is cheap because it is known not to be very safe.

• 26:22Neil deGrasse Tyson?

  Really, you think?

• 26:25Natalie Starkey?

  But people have to live in these places.

• 26:27Neil deGrasse Tyson?

  Location, location, location.

• 26:28Natalie Starkey?

  Exactly, and they're beautiful, so you know, I would quite like to live there.

• 26:32Neil deGrasse Tyson?

  It has good schools, it's got good roads, but you're on the side of a volcano. As much basals as you need, just. I we we went on a trip to Italy and visited Vesuvius, you know, famous for Pompeii. And no, there's no lava there that I saw, but it was hot. We went near the caldera, it's like, oh my gosh.

• 26:52Natalie Starkey?

  Yeah.

• 26:53Neil deGrasse Tyson?

  I was like, whoa.

• 26:54Natalie Starkey?

  And that obviously is very famous for Pompeii.

• 26:57Neil deGrasse Tyson?

  Very famous, infamous.

• 26:58Natalie Starkey?

  Did you visit the ruins? Yeah.

• 26:59Neil deGrasse Tyson?

  Yeah, yeah, of course, of course. And there are vineyards on this side of Vesuvius that are thusly identified on the label. So if you want to get it, so it tastes a bit of ash, I think, I don't know.

• 27:10Natalie Starkey?

  That's the thing about ash, it's really, it's really, really good for soil. So, you know, whilst a huge amount of it coming down the mountain like at Pompeii, you know, is rather devastating. Small scatterings of ash quite often are really great for soil. And it has this great ability that it can absorb water into the soil. So it acts as like a fertilizer in the soil and, and helps to create these amazing crops.

• 27:31Neil deGrasse Tyson?

  Fertilized and irrigated, very, very interesting. Yeah, cool. Matt, give me some more.

• 27:35Matt Kirshen?

  Yeah, well, so this is Nicholas Gublove. And along these lines, Nicholas is asking, should we be worried or afraid of the supervolcanoes of Earth? And what is the most menacing volcano to you in our solar system?

• 27:46Neil deGrasse Tyson?

  Good one.

• 27:47Natalie Starkey?

  Okay, uh, so yeah, supervolcanoes, that's a great subject because we hear about, I think Yellowstone is probably the most famous one we hear about because it's always, you know, in the media, oh, it's gonna erupt, you know, it's gonna erupt next year and it's gonna devastate everything. But the reality is that-

• 28:02Matt Kirshen?

  Right, and that thing of like, it's due is how it's always described, like we're due an eruption.

• 28:05Natalie Starkey?

  And it is always due, you know, but, um, because we don't have a huge amount of data of how often it's erupted. But the thing is with these supervolcanoes is if they do go, it would be massively devastating. And they create caldera eruptions. So you don't really see anything on the surface initially. You don't see a volcano like Mount Fuji. Um, what will happen is that the ground will literally just explode and you'll end up with this massive caldera left behind. And that has happened throughout history. Um, but the thing is with these-

• 28:32Neil deGrasse Tyson?

  But that area still has good schools, right? We can still buy-

• 28:36Natalie Starkey?

  It's very close, isn't it?

• 28:37Neil deGrasse Tyson?

  It could blow up completely, but before that happens, you've got-

• 28:41Natalie Starkey?

  Thing is with supervolcanoes, whilst they have the potential to do that, and, and we think there's a massive magma chamber sort of under the surface that could be bubbling away, let's say, and, you know, potentially gonna erupt.

• 28:51Neil deGrasse Tyson?

  You're a geologist, why don't you know this? For sure, why can't you- We can thump the ground and find oil. Why can't you thump the ground and find where the magma chamber is that might bust?

• 29:03Natalie Starkey?

  So we know that we can do seismic surveys. We know sort of where the ground is hotter and where there's molten material, but it doesn't mean it's all going to erupt in one go. It could be that it has small eruptions and lets off a bit of steam and then it has another one. And so they wouldn't be devastating and therefore it lets off that steam and then it's not going to erupt for, you know, a million years. So then they're almost never as bad as we think they're going to be. And if one is really going to erupt, then we're going to know about it because we're studying them in detail and we'd have a good idea if it was going to do something.

• 29:33Neil deGrasse Tyson?

  Okay, that's encouraging because otherwise they say, oh, it might erupt in the next 4,000 years. That's not helpful.

• 29:38Natalie Starkey?

  Yeah.

• 29:39Neil deGrasse Tyson?

  Just saying, just saying. And how about the other half of that question?

• 29:43Natalie Starkey?

  What was that? I've already forgotten.

• 29:45Matt Kirshen?

  Oh, that was what is the most menacing volcano to you in our solar system?

• 29:49Natalie Starkey?

  Menacing? Oh, but I don't like to give the menacing titles because either they're all lovely, but no.

• 29:55Neil deGrasse Tyson?

  No, stop.

• 29:58Natalie Starkey?

  I guess it's going to be Io.

• 30:00Neil deGrasse Tyson?

  They don't have feelings for the volcano, Dan. They don't have feelings for you. They will melt you in an instant. Okay, vaporize you.

• 30:10Natalie Starkey?

  I guess I wouldn't want to be sitting on Io because I think on Io, you're almost certainly going to be captured by an eruption somewhere. And even if not, you'll have probably lava spattered on you from one of its erupting volcanoes. And, you know, its surface is just incredibly hot.

• 30:24Neil deGrasse Tyson?

  Well, so what about, I know it's not active, but Olympus Mons on Mars, isn't that the biggest volcanic mountain in the whole solar system?

• 30:32Natalie Starkey?

  Yeah, it's massive. You know, it's like three times higher than Mount Everest. It's absolutely enormous. But the thing is, it's not much different to Hawaii. So the volcanoes that we see, you know, you know, on Mauna Loa and Mauna Kea, it's a very similar type of volcano. And actually, they're not particularly scary. When it erupts, like I think, you know, the most recent big eruption was kind of 2018, people were able to outwalk the lava most of the time. You know, yes, it was devastating. It kind of, you know, covered houses and land, but you could outwalk it. So it's not scary.

• 31:04Neil deGrasse Tyson?

  I never heard that sentence before. Let's, Matt, let's outwalk the lava.

• 31:09Matt Kirshen?

  Just go for a nice stroll. Morning constitutional away from the burning rocks.

• 31:16Neil deGrasse Tyson?

  Very cool, very cool. So Matt, let's slip in one more question before we take our second break.

• 31:20Matt Kirshen?

  All right. Well, I'm going to, given that we're talking about Olympus Mons, there are two questions, two different people have written in questions that include that. So Cameron Bishop asks, what properties determine the size of a volcano? And how did these properties allow Olympus Mons to get so big? Could such a volcano form here on Earth? And Jared Sorba says, if Olympus Mons was able to grow so large due to Mars's weak gravity, why don't we see even larger volcanoes on other active bodies, such as some of the larger moons?

• 31:48Natalie Starkey?

  Yeah, brilliant. So yeah, and that second question's got it exactly right. So Mars is about half the size of Earth. So it has less gravity. So it means that things can simply just grow bigger. So if we took an Olympus Mons sized volcano or mountain and put it on Earth, it would basically collapse under its own weight because it would just be too heavy. And so it just, it couldn't form here. It would literally just wouldn't be able to get that big. And the other way that Mars has been able to grow such a large volcano is because it doesn't have plate tectonics. Now, I'm hoping most of the listeners are going to know what plate tectonics is. It's a thing that's very unique to Earth, we think. And it's where the outside of our crust of our planet is basically broken into pieces which move around in relation to each other.

• 32:33Natalie Starkey?

  And they can kind of knock into each other or they create earthquakes when they slide past one another. And they are what creates many of our volcanoes, but.

• 32:41Neil deGrasse Tyson?

  And by the way, just to be clear, y'all only fully embraced that within the last 60 years, right? That's not a forever ago thing.

• 32:50Natalie Starkey?

  Yeah, it was literally, I think it's the 1960s, wasn't it?

• 32:53Neil deGrasse Tyson?

  Yeah, yeah, so 60 years ago.

• 32:55Natalie Starkey?

  First suggested that it was a thing and people were like, no, the man's crazy, you know, he.

• 32:58Neil deGrasse Tyson?

  Yeah, no, I think the suggestion predates that, but before the evidence really gathered to start.

• 33:04Matt Kirshen?

  I didn't know that. And I also really didn't know that Earth was the only. Body that we know of that has this. I thought it was a fairly universal thing.

• 33:10Natalie Starkey?

  No.

• 33:11Matt Kirshen?

  Planets.

• 33:12Natalie Starkey?

  So that's how we get lots of our volcanoes. But the other type of our volcanoes luckily come from mantle plumes. And this is the type, again, Hawaii is the classic example. And this is a big chimney of hot rock that rises from the interior of the earth, possibly as deep as the core. And it comes all the way up through the planet and then erupts molten lava at the surface. And these are very long-lived features on our planet. Now, if you just imagine this chimney of rock in the planet and these plates are moving over the top of that. So what we have, what happens at Hawaii is we get this chain of volcanoes. This, you know, chimney of rock keeps erupting and the plate moves over it and we get volcanoes, you know, going along in a linear chain. So the most recent ones amount of Larama Kea. Now, in Mars, we've got exactly the same thing.

• 33:54Neil deGrasse Tyson?

  Yeah, so this is an archipelago, right? Isn't that what an archipelago is?

• 33:57Natalie Starkey?

  Yeah, exactly.

• 33:58Neil deGrasse Tyson?

  And, and many of the Caribbean islands are, so what you're saying is it's not a continuous busting through of the, of the plate. It busts through and then it stays calm for a while and over that period, this plate shift and it's okay, time to bust through again. Oh, there you go. And so.

• 34:15Matt Kirshen?

  That completely, but that's, that's fascinating to me because I, in my head, I, these sort of chains of volcanoes, I assume they were like all along a fault line or something like that. But you're saying it's, it's almost more like a sort of, like a factory line where this, they're moving up. Like the earth is moving along a conveyor belt and every cell that it punches a hole through it and it moves on a bit more and punches another hole through.

• 34:34Natalie Starkey?

  Precisely. And so if you go to Honolulu and people are like, oh, it's volcanic, could it erupt? You're like, no, you can't because it's nowhere near that plume now. So that is almost certainly not going to happen.

• 34:42Neil deGrasse Tyson?

  But that other island, that's the one.

• 34:44Natalie Starkey?

  Yeah, that's the one we need to worry about with the molten lava crater at the top, yeah.

• 34:49Neil deGrasse Tyson?

  And also I think I'm right in that the big island in Hawaii would not be sustainable were that fully on land. That the buoyancy of rock and water allows that to build as high as it did. Through from the bottom of the ocean through the ocean surface and then above the ocean surface because it doesn't weigh as much simply because it's half of it is sitting in water.

• 35:12Natalie Starkey?

  Yeah, exactly. Yeah, because I think people forget with those islands that, you know, what we see above is not even half of it.

• 35:17Neil deGrasse Tyson?

  And in the middle of the fricking Pacific Ocean. Right.

• 35:20Natalie Starkey?

  Yeah.

• 35:21Neil deGrasse Tyson?

  Where it goes really, really deep. We've got to take another quick break, another quick break. And when we get back, Matt, you've got more questions for Natalie Starkey, our geologist turned astro person, millkeeper on StarTalk. We're back, StarTalk. Neil deGrasse Tyson here. Matt, where can we find you on social media?

• 35:53Matt Kirshen?

  You can find me at Matt Kirshen on the various things and probably Science is my podcast.

• 35:59Neil deGrasse Tyson?

  Okay.

• 36:00Matt Kirshen?

  And that's on all the podcasts.

• 36:01Neil deGrasse Tyson?

  Wherever podcasts are sold near you. Yes, okay.

• 36:04Matt Kirshen?

  Yeah. Yeah, I'll just get your local bookshop for my podcast.

• 36:08Neil deGrasse Tyson?

  There you go. And Natalie, where can we find you on social media?

• 36:11Natalie Starkey?

  I'm at Starkey Stardust on, yeah, all the platforms.

• 36:15Neil deGrasse Tyson?

  Starkey Stardust, S.T.A.R.K.E.Y.

• 36:19Natalie Starkey?

  E.Y.

• 36:20Neil deGrasse Tyson?

  Starkey Stardust, I love it. Yeah, yeah. So I think, I think we had to take a break before you completed the answer to why Olympus Mons is so big on Mars. So, so we learned that the Hawaiian chain of islands, they're all volcanic and that's just magma punching through in a new spot as the plate tectonics take it by. So Mars, I think, doesn't have plate tectonics. So is that what happened there?

• 36:47Natalie Starkey?

  Yeah, we don't, we don't think it does. We haven't got any evidence for it there. Now, obviously, it's not an active planet today, so we know it's not happening today. Trying to work out whether it happened in the past, we just don't have any evidence for it. So we don't think it did. So we call it a stagnant lid planet, basically just one big crust and it didn't move. So what happens there is if you've got one of these mantle plumes coming up from the interior of the planet onto the surface, that plate isn't moving anywhere. It's just going to carry on erupting for millions of years.

• 37:14Neil deGrasse Tyson?

  Through the same hole, through the same hole.

• 37:16Natalie Starkey?

  Through the same hole, maybe even a billion years or more. So, yeah, it just grows larger and larger and larger in one place and that's exactly what happened with Olympus Mons.

• 37:25Neil deGrasse Tyson?

  All right, cool. Cool. Which is the largest volcanic mountain in the solar system?

• 37:31Natalie Starkey?

  I think it's the largest mountain, isn't it?

• 37:32Neil deGrasse Tyson?

  Yeah, yeah, yeah. Okay, good, good. All right, Matt, keep them coming.

• 37:36Matt Kirshen?

  Okay, well, this is a question Chester Lipschitz has sent in that touches on both of your areas of expertise. Do today's volcanic activities have much of any impact on the cooling down and gradual solidifying of the core? If so, how long would it take? Would we lose our ability to maintain a stable magnetosphere and atmosphere before we even have to worry about the problems the sun is going to give us in a few billion years?

• 38:01Natalie Starkey?

  Oh, wow.

• 38:02Neil deGrasse Tyson?

  Man, what an apocalyptic touch. Does he get any sleep at night?

• 38:05Matt Kirshen?

  Right. So I think he's basically then asking, like, as heat is coming out through these volcanoes, is it cooling down the inside of the Earth? And is it doing it at such a rate that it's going to start changing how the Earth?

• 38:15Neil deGrasse Tyson?

  And let me simplify that question to Natalie. Why is Earth still hot?

• 38:19Natalie Starkey?

  Yeah, no, that's exactly it. So the volcanoes are basically just a manifestation of a planet cooling itself down. So it has all this internal heat and it needs to go somewhere and volcanoes let that heat escape into space.

• 38:31Neil deGrasse Tyson?

  Which means we are cooling down.

• 38:33Natalie Starkey?

  We are cooling down. So, but luckily, we have plenty of heat. So we've got two, main two types of heat in most of the planets will be the heat that was left over from the formation of the planet. So that when the planets formed, it was all a bit chaotic and things were colliding with each other. And basically kinetic energy of two objects colliding into each other turns into heat energy. And so it gets trapped within the cores of most of the planets, or all the moons, in fact. So we've got a lot of heat from four and a half billion years ago, and it's been trapped in ever since. Outside of the core, we've got a mantle which is made of silicate rock. So these are kind of the basals and stuff we were talking about. That's a really good insulator. So it keeps that, it's kept that heat inside the planet. The larger you are, the more heat you can retain.

• 39:16Natalie Starkey?

  Now, the other way that we create heat is actually continuous process, and it's nuclear heat. So we've actually got radioactive decay going on within our planet. Basically, atoms that are unstable decay to more stable atoms. And they release heat during this process because they release little atoms that then collide with other things inside the planet and create heat. Now, it sounds like it wouldn't be very an important process, but actually there's so much decay going on in the planet that we're creating about half our current day heat from that process.

• 39:44Neil deGrasse Tyson?

  So why isn't Mars also creating heat?

• 39:47Natalie Starkey?

  So it is, but it's cooled down a lot more now because it started off smaller, so it never had as much heat to start with. And then because its mantle is smaller and its crust where it has all these heat producing elements, it then has just lost that heat.

• 39:59Neil deGrasse Tyson?

  Okay, so we have volcanoes and Venus still has volcanoes and we're sister planets.

• 40:04Natalie Starkey?

  Yeah, Venus is probably a similar temperature inside. We talk about the surface temperature of the planets. It almost doesn't really relate to what's going on inside. So Mercury being right next to the Sun can even have ice on its surface.

• 40:15Neil deGrasse Tyson?

  So I love that.

• 40:16Natalie Starkey?

  Inside is still molten.

• 40:17Neil deGrasse Tyson?

  Another side of that question was, if it does cool down, we might lose our magnetic field. Because you drive a magnetic field by the movement of conducting materials.

• 40:29Natalie Starkey?

  Yeah.

• 40:29Neil deGrasse Tyson?

  And when you move charges, you, within a field, you generate, within an electric field, you can generate a magnetic field. And so we rely on a molten inner region of iron, itself a conducting material, to generate a magnetic field, which shields us from certain forms of solar wind that could then strip our atmosphere of very, of molecules that we care about, okay? Including the water molecule, right? So, so did I characterize that accurately there?

• 41:09Natalie Starkey?

  Yeah, perfect. So yeah, our outer core is actually molten and our inner core is solid. So it's that molten iron rotating around inside the planet that keeps our magnetic field alive. And without it, we wouldn't be here because life, we just would be bombarded with radiation.

• 41:23Neil deGrasse Tyson?

  Or we'd be living just underwater.

• 41:26Natalie Starkey?

  We'd maybe be living underwater because you would be, if you had an ice cover like you find at Europa, which is obviously sitting next to Jupiter, which has this horrible magnetic field if you're life. And it could be the life, if you're life.

• 41:38Neil deGrasse Tyson?

  Otherwise, it's just fine. If you're a rock, what do you care?

• 41:43Matt Kirshen?

  I mean, if you're a robot, then you might be in trouble as well. So that's worth considering.

• 41:46Natalie Starkey?

  Yeah, no, and that's we do have to really protect space equipment that we send out there.

• 41:50Neil deGrasse Tyson?

  Good point, Matt.

• 41:51Natalie Starkey?

  From radiation in space because, you know, you know, this can damage cameras very easily. So, yeah, it's something we have to worry about. But Mars, if we go back to Mars, it was, it did have a molten interior and then it no longer does. So it's lost its magnetic field. So this is why we talk about life might have been there in the past because it had all the right conditions, but.

• 42:09Neil deGrasse Tyson?

  But it also means terraforming Mars might have bigger challenges than we think.

• 42:13Natalie Starkey?

  Yeah.

• 42:14Neil deGrasse Tyson?

  Because you might be able to turn it into Earth, but to sustain it requires the rest of this shielding to happen.

• 42:20Natalie Starkey?

  Yeah, we could live in caves and I think it would be miserable, but, you know, maybe people want to go and do that. But we would need to live underground to protect ourselves, using the rock to basically shield us from the radiation.

• 42:31Neil deGrasse Tyson?

  Okay.

• 42:32Matt Kirshen?

  So my favorite thing about the show is I can make a stupid joke about robots and it turns out I actually said something smart.

• 42:38Neil deGrasse Tyson?

  That's a very insightful point, Matt.

• 42:41Matt Kirshen?

  Thank you. That's what I was going for. I appreciate that, two scientists there.

• 42:44Neil deGrasse Tyson?

  Okay, keep it coming. What else you have? We have a few more questions.

• 42:48Matt Kirshen?

  This is, this is also touching on Neil's expertise as well because Marcus Gustafson says from Sweden asks, can asteroids develop volcanoes and would that make its orbit unpredictable because of the thrust it would generate?

• 43:00Neil deGrasse Tyson?

  Oh, cool.

• 43:01Natalie Starkey?

  That's really cool. And yes, yes, yes, it can. So we've actually discovered that some of this, the asteroids, like some of the Ceres and actually that's what ice volcanoes on it. And there's a mission called Psyche, which is a NASA mission. I think, I don't know when it's launching, not, not long now. It's going to this asteroid called Psyche 16. And they think it had iron volcanoes on it potentially way in, way in the past. Now, whether those volcanoes have an effect.

• 43:27Neil deGrasse Tyson?

  But just to be clear, and I don't want to be pedantic or anything, but Ceres got upgraded in its designation in the solar system.

• 43:35Natalie Starkey?

  This is true, unlike Pluto.

• 43:37Neil deGrasse Tyson?

  Yeah, so Pluto got downgraded from planet, Ceres got upgraded from asteroids and they're both dwarf planets now. So.

• 43:44Natalie Starkey?

  Yeah.

• 43:44Neil deGrasse Tyson?

  So I will not accept you to cite Ceres as a place for asteroidal volcanoes.

• 43:50Natalie Starkey?

  It's in the asteroid belt. I'm going to call it an asteroid. It's a dwarf planet and an asteroid.

• 43:57Neil deGrasse Tyson?

  Okay, I guess since location does matter to geologists because magma outside of a volcano is called lava.

• 44:04Natalie Starkey?

  Mm hmm.

• 44:05Neil deGrasse Tyson?

  So that's how you roll. So also, of course, comets, as they come near and far from the sun, plumes will develop that do alter their trajectories, right?

• 44:16Natalie Starkey?

  Yeah.

• 44:17Neil deGrasse Tyson?

  And so with comets, predicting their orbits is a highly risky business, not risky, it's highly uncertain activity, simply because you don't know where the next plume is going to come out, that will then have the comet recoil and give you a different kind of orbit than you were expecting.

• 44:34Natalie Starkey?

  Yeah, and when they go near the sun, they can explode or pieces can come off. And then obviously, there are different size and shape to what they were before they went around the sun. I know, it's crazy.

• 44:42Neil deGrasse Tyson?

  They're gonna explode, disintegrate or get eaten by the sun entirely. Yeah. Matt, time for a few more.

• 44:50Matt Kirshen?

  Well, yeah, well, this is obviously the counterpart to this question from, and I hope I'm getting your name close to correct, Zengkutibenz asks, can an eruption have such power to send rocks to space? If a giant eruption happened in Yellowstone, would it send rocks to space, which would then fall back down on Earth? Is the second part of that question. And that question comes from Hungary.

• 45:12Natalie Starkey?

  Yeah, so I guess once you're in space, you're in space. You're not going to probably come back very easy, but that wouldn't really happen on our planet because we've got so much gravity that I just don't think we could have a strong enough, powerful enough eruption that you could get out into space. But obviously, in other places, we know that Enceladus, its plumes, you know, go 200 kilometers high and make the E-ring of Saturn. So sure enough, that is, you know, eruptions going into space. But I may be wrong, but I don't, I don't think that could happen on Earth. But sure enough, like, our eruptions do go very high into the stratosphere quite often with these Polynian-style eruptions, which is what happened at Vesuvius. And the material then, the ash and the gases, kind of encircle the planet, but within, you

• 45:53Natalie Starkey?

  know, our atmosphere and can block out the sun for weeks and months to come. And that can create lots of kind of long-term damage to the planet in a way.

• 46:02Neil deGrasse Tyson?

  Also, even if it did eject from the volcano at escape velocity, the atmosphere is going to tamp that down. And it will not likely ever escape the earth because it won't maintain that velocity as it ascends.

• 46:15Natalie Starkey?

  Yeah.

• 46:16Neil deGrasse Tyson?

  Or maintain the velocity necessary to continue to escape the earth. But there's more than one sci fi film where we have astronauts on on on comet surfaces and on asteroidal surfaces where it rotates into view of the sun. There's a plume that busts forth and people, hardware is get kicked completely off the asteroid, never to return.

• 46:39Natalie Starkey?

  Yeah, and that it's something they worry about with comet missions with the Rosetta mission. They landed on that comet and they had to choose somewhere that didn't look very active, didn't have, you know, an active plume coming out because, you know, they were genuinely worried that that spacecraft, you know, little lander would get shot off the surface and be lost into space forever. So it is quite a worry.

• 46:57Neil deGrasse Tyson?

  Yeah, yeah. That'd be a cool, a cool video, though.

• 47:01Natalie Starkey?

  Yeah.

• 47:03Neil deGrasse Tyson?

  It's like, whee! Like R2, you know, getting kicked out of the thing.

• 47:08Matt Kirshen?

  I guess in the sci fi world, if you're thinking about it, if you do have an ability to predict where these plumes are going to come from, that's a possible launching site to save fuel by using that as a...

• 47:17Neil deGrasse Tyson?

  Very good, man!

• 47:18Matt Kirshen?

  As a trampoline.

• 47:19Neil deGrasse Tyson?

  Oh, my God, so that would have to be a desperate situation where, oh, we're out of fuel, how are we ever going to get back? Wait a minute, there's a crash here. Let's do that. And then then that saves them. That reminds me, there's a movie called Marooned, where it's back in the 60s, before we landed on the moon, and there's some astronauts in space and something goes wrong and they have to be rescued. But a hurricane was coming through Florida and over Cape Canaveral, so they couldn't launch a rescue mission. And then someone figures out, wait a minute, the eye of the hurricane is going to go over Cape Canaveral. So they they they connected the countdown to the... This was, I was very young, so I didn't know hurricanes had eyes. I didn't know any, or that it's beautiful in the middle of a hurricane. I didn't know any of this, or that Florida was hurricane prone, right?

• 48:04Neil deGrasse Tyson?

  And so they actually launch it until you see this launch coming out from the center of the hurricane. It was beautiful, it was beautiful. Beautiful concept.

• 48:12Matt Kirshen?

  I'm not sure how exactly they wheel the rocket out through the hurricane, waiting for the eye to get in. If I know anything about rocket launches, they're quite easily postponed. It doesn't take much, it doesn't take much for them to say like, this isn't safe, we need to wait another couple of days.

• 48:26Neil deGrasse Tyson?

  Yeah, but it was a cool, it was a cool move, though. Yeah.

• 48:28Matt Kirshen?

  Yeah.

• 48:29Neil deGrasse Tyson?

  Okay, time for a couple more questions. Maybe one more question. One more, time for one more question, Matt.

• 48:35Matt Kirshen?

  Okay, well, I like, I like this one because there's been some other questions that I think we've, we've covered anyway, just through questions, things that have come up naturally. So Boris Maganik, I again, I'm Maganik, I hope I'm getting your name close, says, okay, here's a silly and possible, possibly ignorant one. I say it's not ignorance, I, I'm the one who asks the ignorance, stay in your lane.

• 48:56Matt Kirshen?

  There's only one room for one ignorant person on this show. But Boris asks, is it possible that a regular mountain can become a volcano? Or a hun, or are 100% of volcanic mountain shapes and mass created by the first eruption itself?

• 49:08Natalie Starkey?

  Yeah, yeah. So once you, if you've just got a normal mountain and is created through normal mountain processes, which is usually from plate tectonics. So you've got two plates colliding and nothing gets melted, they just kind of crumple up against each other. And because they're being forced together, you know, a few centimeters per year, that's how we get the Himalayas. So those mountains and, you know, Mount Everest are not volcanic, they never will be. They're just getting taller and taller every year. Because, you know, those plates are crushing together and pushing up crust above the surface. So no, we, sorry, no, no, no big mountains will become.

• 49:41Neil deGrasse Tyson?

  So the subcontinent, no, it didn't get the memo that like Russia's in the way, right?

• 49:46Natalie Starkey?

  Yeah, exactly.

• 49:49Neil deGrasse Tyson?

  It's like, I'm, I'm still moving, I'm still going.

• 49:51Natalie Starkey?

  Just keep going.

• 49:54Neil deGrasse Tyson?

  So Natalie, I'm wondering, in the, in the vein of that question, could we actually take a spot on Earth and drill to where the, the molten rock is and sort of force a volcano to, to erupt? Where we choose it to?

• 50:08Natalie Starkey?

  I guess if we knew the magma was there, that would technically, not technically be possible because that'd be really hard to do.

• 50:14Neil deGrasse Tyson?

  You're a geologist, you know where this stuff is.

• 50:17Natalie Starkey?

  Drilling into hot stuff is never going to be easy because everything's going to melt anyway. But like, if we knew there was a magma chamber there, we probably know a volcano is there anyway. Like, you're not going to just get a magma chamber without a volcano. But actually, what we do do a lot is kind of use the heat that's given out by these magma's sitting below the crust to generate electricity. So in Iceland, they do this a lot. Iceland is obviously all volcanic. It sits on the mid ocean ridge and it's also got a mantle plume there. So it's a massively volcanic place. And they generate.

• 50:43Neil deGrasse Tyson?

  We film cosmos, many scenes in Cosmos there. Because, because you have, it looks like the, you aim the camera this way, it's like. Earth is forming. You aim it here, it's like, there are these plumes, where's the dinosaur? You know? They had all manner of earth formation scenarios, all without any kind of set design. It was all, it was already there.

• 51:05Natalie Starkey?

  And the great thing is that there's so much heat, just literally just under the crust there, that they, they just generate all their electricity for free because they can use geothermal energy. So they pump down water into the crust, it gets heated up and gets shot back up, and they could use that to.

• 51:19Neil deGrasse Tyson?

  By the way, that, as I heard, that was only in recent decades, until the nineties, I think. They were still using fossil fuels. And somebody said, what the hell are you doing?

• 51:27Natalie Starkey?

  You've got all this heat, yeah, I do feel with it. And they have so much.

• 51:30Neil deGrasse Tyson?

  I, I think they actually send heat on their roads.

• 51:33Natalie Starkey?

  I was gonna say, because it is cold.

• 51:34Neil deGrasse Tyson?

  Yeah, yeah, they, they send heat on the roads and it melts all the ice, so then.

• 51:37Natalie Starkey?

  Yeah, so they don't, yeah, they don't have to grip the roads, so, yeah.

• 51:41Matt Kirshen?

  I found out recently that Iceland has the highest electricity use per capita of any country in the world by quite some way, which makes them sound like they're not green, but it's the opposite because they do everything with basically fossil fuel free electricity.

• 51:54Neil deGrasse Tyson?

  Yeah, and if you, and, and if you just tap and heat out, you, you leave the lights on, who cares?

• 51:59Natalie Starkey?

  And then they, you can, you can have all these saunas everywhere and hot swimming pools and everything. So they have loads of swimming pools just because they can heat them really easily. And they're all outdoor pools and, you know, when it's really cold and you're like, oh, that's gonna be horrible, but it's great.

• 52:10Neil deGrasse Tyson?

  Right, right, right. Uh, so let me, uh, just to end with, can I reverse that question? And, um, if, I, I heard that the name of a, of a fraternity, uh, I mean, it was a, it was a joke name. It's called I Tap a Keg, right? Okay, so. Can we, can there be a volcano that we think is going to erupt? And then can we tap it off the side and have it kind of like a release of the pressure to delay what might be a larger singular eruption of the cone?

• 52:47Natalie Starkey?

  No, I think the problem is we just still don't know enough about volcanoes to be able to predict their behavior.

• 52:53Neil deGrasse Tyson?

  Damn Natalie, I thought you knew, Natalie.

• 52:55Natalie Starkey?

  I know, I'm sorry, I'm trying my best.

• 53:00Natalie Starkey?

  But basically with a lot of volcanoes, like there's the Montserrat in the Caribbean is a classic example, it's this volcanic dome which sits above the surface, but it's really unstable. So, you know, even a lot of rainfall can destabilize the slopes of that volcano because it's just not very well consolidated, mashed together, and that can destabilize the magma chamber underneath and then create a massive eruption. So basically you're taking off kind of the lid of the pressure cooker a little bit, you're just releasing a bit of pressure and then it can then erupt really badly. So we wouldn't want to meddle. I think we have to leave nature to do its thing and the best way for us to get away is just to move people away.

• 53:34Neil deGrasse Tyson?

  That's so defeatist. Wait, wait till your kids become geologists and say, "Ma, that's so old fashioned." Yeah, we just tap this energy here, we run the energy needs of the town, we get that the volcano will never erupt and we got to, we're good. Wait till the next generation, they'll figure it out.

• 53:52Matt Kirshen?

  But there is one possible, I don't know if you have time, but just to squeeze in one extra question from Moses Conrad Norman who asks, can you have a planet that is entirely volcanoes and volcanic activity?

• 54:01Natalie Starkey?

  Yeah, I guess Io is the closest one to that. And it's almost like our planet four billion years ago. So our planet four billion years ago was almost certainly covered in volcanoes and most of the surface was just very hot, probably molten, and volcanoes were going off all over the place. So that is what's happening at Io still. It's not quite that bad, but it is very, very active. So yeah, like you definitely, it's just, it's got, again, it's got that kind of tidal energy inside because it's right next to Jupiter, this massive planet. So it's being squashed and squeezed, friction is happening inside and it's creating heat and that's just a continuous process.

• 54:35Neil deGrasse Tyson?

  And let me just put this to bed right here. So in, in the old days, we would, well, maybe even in modern times, we would see drawings of dinosaurs and there was always a volcano on the horizon, as though dinosaurs, which was a hundred million years ago, somehow Earth was covered with volcanoes a hundred million years ago. But that's like yesterday compared to the geologic timescale. So they, that's all wrong, I guess. Is that correct?

• 55:02Natalie Starkey?

  Yeah, I mean, yeah, there were volcanoes obviously at the time, but not like that kind of era that we see where they're just, you know, it's all volcanic.

• 55:09Neil deGrasse Tyson?

  Right, right. It's not every direction you look, there's a dinosaur chewing the...

• 55:12Natalie Starkey?

  No, exactly. They needed plants to eat and stuff and plants don't like volcanoes very much, so.

• 55:16Matt Kirshen?

  But there are dinosaurs on Io?

• 55:18Natalie Starkey?

  Well, we don't know.

• 55:20Neil deGrasse Tyson?

  That's not what we said, Matt.

• 55:21Natalie Starkey?

  We haven't seen them yet.

• 55:23Matt Kirshen?

  We need to get back.

• 55:26Neil deGrasse Tyson?

  All right, we got to call it quits there. Natalie, it's always great to have you. And again, thanks for being the author of our current space show with the Hayden Planetarium, Worlds Beyond Earth. Matt, we'll find you on Probably Science. Still waiting for my next invitation to appear as a guest.

• 55:40Matt Kirshen?

  The second you have anything you want to come on and talk about, your next book, or just a whim, the door is wide open.

• 55:48Neil deGrasse Tyson?

  All right, very pleased to hear that invitation get extorted from you.

• 55:54Matt Kirshen?

  Very much the other way around. Anytime, anytime.

• 55:56Neil deGrasse Tyson?

  I'm Neil deGrasse Tyson, director of that planetarium where Natalie Starkey wrote the latest space show. As always, four-star talk. I bid you to keep looking out.