Cosmic Queries – Comet NEOWISE

Neil deGrasse Tyson, comic co-host Negin Farsad, and cosmochemist and author Natalie Starkey, PhD, answer fan-submitted questions about Comet NEOWISE, Halley’s Comet, the Oort Cloud, and much, much more!

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.

• 0:15Neil deGrasse Tyson?

  This is StarTalk. I'm Neil deGrasse Tyson, your personal astrophysicist and your host. This is a cosmic queries edition, and we were long overdue to get a cosmic queries on the comet that has been in the sky. And so I had to bring in some expertise for that. But before we get to that, let's introduce my co-host for this episode, Negin Farzad. Negin, welcome back.

• 0:39Negin Farsad?

  Oh, hi Neil. How are you?

• 0:42Neil deGrasse Tyson?

  After your first visit to us, you didn't run away and not come back? You came back.

• 0:48Negin Farsad?

  I felt my head getting like larger with facts and knowledge, and I thought, let's do this again.

• 0:56Neil deGrasse Tyson?

  Okay, one day your head will not fit on the screen, and then we'll know you're doing the right thing.

• 1:02Negin Farsad?

  I'm taking measurements.

• 1:04Neil deGrasse Tyson?

  Negin Farzad is a stand-up comedian, and if I remember correctly, you wrote a book called How to Make White People Laugh.

• 1:12Negin Farsad?

  Indeed.

• 1:13Neil deGrasse Tyson?

  That's a crazy title. That's just crazy.

• 1:18Negin Farsad?

  I would like a comet to be named after my book.

• 1:25Neil deGrasse Tyson?

  And also, you host a podcast Fake the Nation.

• 1:29Negin Farsad?

  That's right.

• 1:30Neil deGrasse Tyson?

  Yeah, these are very, very, uh, these are terms you just gotta, you gotta just pick up that book and listen to that podcast, because you wanna know what the hell, where are you coming from on this?

• 1:41Negin Farsad?

  You'll enjoy them. They're, they're fun, but they have like, you know, just a lot less science, but you'll still love them.

• 1:50Neil deGrasse Tyson?

  And, and you, you write this not as a white person. You write this as a sort of Middle Eastern heritage person?

• 1:58Negin Farsad?

  That's right. I'm an Iranian-American Muslim. You can probably tell from my voice.

• 2:02Neil deGrasse Tyson?

  Yes, I was gonna pick it out.

• 2:05Negin Farsad?

  It's so easy to tell on podcasts.

• 2:10Neil deGrasse Tyson?

  So delighted to have you back. And we have a friend of StarTalk, Natalie Starkey. Natalie, welcome back.

• 2:17Natalie Starkey?

  Hi, Neil.

• 2:18Neil deGrasse Tyson?

  Yeah, you're our comet expert and you're dialing in or zooming in from Cambridgeshire, the UK.

• 2:28Natalie Starkey?

  All the way in England.

• 2:29Neil deGrasse Tyson?

  Very cool. Well, welcome.

• 2:32Natalie Starkey?

  Thank you.

• 2:33Neil deGrasse Tyson?

  And many people don't know that you wrote our most recent space show at the Hayden Planetarium, which features planets as objects and planets as astronomical targets of interest. So just thanks, thanks for coming in to do that.

• 2:50Natalie Starkey?

  No, and of course we went to visit a comet as well because how could I resist? If we're going to go and look at things in the solar system, I'm like, we're going to get a comet in there. So, yeah.

• 2:59Neil deGrasse Tyson?

  Exactly, exactly. So when the planetarium opens back up, maybe you'd come back and visit.

• 3:04Natalie Starkey?

  Yeah, I can't wait. I can't wait.

• 3:06Negin Farsad?

  Can I give listeners a little bit of insight about the two of you? The green room chit chat before we started recording was about helium. Ladies and gentlemen.

• 3:19Neil deGrasse Tyson?

  This is exciting stuff.

• 3:22Negin Farsad?

  That is what, I mean, so if you think they're talking about like, you know, Kanye West or something before we start recording, no, they're talking about helium before we start recording. Just so everyone's clear, these people are talking about it all day long, not just for this hour.

• 3:39Neil deGrasse Tyson?

  Natalie Starkey is a colleague and who's a professor at the, is it the Open University?

• 3:46Natalie Starkey?

  Oh, I'm actually a public engagement officer now.

• 3:49Neil deGrasse Tyson?

  A public engagement officer?

• 3:50Natalie Starkey?

  Yeah, I'm at the Open University. So I do a lot of physics, public engagement because I discovered doing a lot of research. I actually just love talking about science all the time.

• 3:58Neil deGrasse Tyson?

  Okay, well, excellent. Very excellent. And you've got a book and you've got videos and so you're out there. You're trying to do what we're trying to do. So we're.

• 4:08Natalie Starkey?

  Yeah, I'm trying to copy you, but I just.

• 4:11Neil deGrasse Tyson?

  No, that's fine. You want to take my place? I'll go to the Bahamas. You take my place. How about that?

• 4:17Natalie Starkey?

  That's fine.

• 4:20Neil deGrasse Tyson?

  Alright, so your expertise, I'm intrigued because your expertise in the solar system grew up out of your expertise thinking about Earth as a planet, as a geological object. So that gives you a different kind of angle into what comets are than an astronomer would have.

• 4:37Natalie Starkey?

  Yeah, exactly. Because, you know, I started out as a geologist. I've always been fascinated by volcanoes. That was what got me into science. And then what I discovered from that is I loved doing chemistry on rocks. And then it just sort of grew from there. And my PhD was looking at understanding the Earth as a planet, how it formed four and a half billion years ago, how it evolved since then. And so it was quite sort of a natural step when I saw the postdoc, which is the research position I had after my PhD. It was looking at comet and asteroid samples and doing the same kind of chemistry on them, but it was just looking at space rocks instead. And I thought, oh my goodness, that's so cool. I don't know anything about space rocks, but I'm going to jump in and give it a go. And I've just not looked back since then. I absolutely love it. I still love volcanoes.

• 5:17Neil deGrasse Tyson?

  Yeah, I don't mean to be biased, but space is cooler than geology.

• 5:21Natalie Starkey?

  Oh, I don't know. I don't think you need geologists in space.

• 5:24Negin Farsad?

  Neil, you gotta be careful because I hear geologists can be very violent. So you might get some attacks after this.

• 5:37Neil deGrasse Tyson?

  They have rocks that they can throw.

• 5:39Negin Farsad?

  Like actual rocks that they can touch. You can't touch your rocks, Neil.

• 5:44Natalie Starkey?

  We use hammers a lot to break those rocks. And I've actually hit my own shin with my own rock hammer before by when I actually missed the rock. It was so painful. So like, yeah, I'm not very good.

• 5:54Neil deGrasse Tyson?

  Negin, if she can do that to herself.

• 5:56Negin Farsad?

  I mean, imagine what she can do to others. I've noticed like a hint of violence in you.

• 6:05Neil deGrasse Tyson?

  So Natalie, you still have your eyebrows. So whatever love of volcanoes you had, you didn't lean too far in to have them.

• 6:13Natalie Starkey?

  No, no. I've never seen like an actual eruption, but I've been on an active volcano many times and, you know, just. And a volcano in the Caribbean that I worked on, you can literally hear the thing roaring as you're standing next to it. All the gases escaping from it is absolutely amazing. I never knew that before I actually went to one and actually sort of had to understand its temperature and look at it in detail and measure its gases. But they're just, they're fascinating. I love volcanoes.

• 6:38Neil deGrasse Tyson?

  And so we've got volcanoes in the solar system that are places other than Earth. So it's cool to have you helping us think about those problems.

• 6:45Natalie Starkey?

  That's a good link. Because actually, my book coming out next year is all about space volcanoes. So I've written, yeah, my second book's just finished. So it's, yeah, gonna be a while till it comes out, but it's about all the volcanoes in the solar system made of ice or made of rock.

• 6:57Neil deGrasse Tyson?

  Right, ice volcanoes, that's right. Spewing chunks of ice. We think of volcanoes as hot objects, but it's really just objects where there's a lot of pressure. Is that a fair way to think?

• 7:06Natalie Starkey?

  Yeah, it's basically the effort a body makes to cool itself down. But if that thing is already cold, it just has to be a little bit warmer inside and a bit colder outside, then it wants to lose that heat.

• 7:17Negin Farsad?

  By the way, can I say that space volcano is how I described an ex-boyfriend who was both a pothead and had a temper. So I didn't actually realize it was a real thing. So I've been learning a lot right now.

• 7:31Neil deGrasse Tyson?

  Yeah, I didn't know potheads have tempers. I thought that.

• 7:34Negin Farsad?

  That was what was remarkable. That was what was weird about him, you know?

• 7:40Neil deGrasse Tyson?

  So Negin, did you collect questions for us for this Cosmic Query?

• 7:44Negin Farsad?

  I did. There's so many great questions.

• 7:46Neil deGrasse Tyson?

  Well, let's head right in.

• 7:48Negin Farsad?

  Let's head right in with Philip Lyons from Patreon. He asks,

• 7:53Neil deGrasse Tyson?

  Oh, well, you do Patreons first, because they pay.

• 7:55Negin Farsad?

  Patreons go first, because they really support. "I understand that comet Neowise was recently discovered in March. Given how long its orbital period is around the Sun, how can we be sure that it originated in our solar system?"

• 8:09Neil deGrasse Tyson?

  Good one. Natalie.

• 8:10Natalie Starkey?

  That is, yeah, I always, I'm kind of always nervous during Cosmic Queries, because it feels like an exam. Like, I know this is a test. I don't know what the answer is. What am I gonna ask? I'm so scared. Like, I do, right, I know it, I know the answer. Right. Okay, so the thing about comments is that...

• 8:27Neil deGrasse Tyson?

  Wait, so Natalie, I see you like peeking at your palm, your hand, with your nose.

• 8:31Natalie Starkey?

  It's my nose.

• 8:34Negin Farsad?

  All right, Natalie, you have about 30 seconds to answer this question and go.

• 8:39Natalie Starkey?

  Right, so comets are really small, let's just get that out there first, okay? So they're really hard to see in the solar system. So when they're coming in towards the inner solar system, and that's the only time we can really see them in any detail.

• 8:52Neil deGrasse Tyson?

  Wait, quantify how small, how small?

• 8:53Natalie Starkey?

  Uh, well, the Neowise is about five kilometres across. So is that like three miles if you're in old money? And so that's not huge. If we're looking at that from the earth and it's really far away, we're not going to see it very easily. And now, most of the time, comets live really, really far away. They live in the far outer reaches of the solar system, past the orbits of all the planets. And they live in somewhere called the Kuiper Belt, and then even further out, this kind of theoretical region called the Oort Cloud. And so there's lots of them out there, possibly billions of them. And sometimes they get diverted into the inner solar system to bring them a bit closer to the sun, which is what happened with Neowise. Now, it comes in and actually it was on a different orbital period to start with, but its interaction with the sun changed its orbital period, so it got longer.

• 9:38Natalie Starkey?

  So I think it's gone from around four thousand years to around six thousand years to get around the sun and all the way back again. So it's a very, it's a long period comet is what we say. And this tells us that it came from very far away, because if it had come from closer to us, it wouldn't take so long to go around the sun. And so we worked out its orbital period and we know it's not coming back for quite some time. And now, what was the end of that question? Have I answered that correctly?

• 10:02Neil deGrasse Tyson?

  Well, wait, so is, how do we know it's from this solar system and not from somewhere else?

• 10:06Natalie Starkey?

  Ah, okay, so the reason we know it's from this solar system is mostly related to its speed. Now, if something was coming from another solar system, another star system way out, then it would be travelling extremely fast to have exited its solar system and to be orbiting, and to be travelling through the galaxy. Now, we've had that happen before. There was a, an object that was called a Muamua, which was this strange object that we saw very last minute. And we didn't know if it was a comet or an asteroid. We're still not a hundred percent sure. We think it was probably a dead comet. And but it came from some other star system. And it travelled through our solar system so quickly that it didn't even get captured into orbit around our sun. It couldn't have cared less that we were here. It just went straight through, zooming straight past. So the fact that we can kind of measure the speed

• 10:51Natalie Starkey?

  or the velocity of this comet in space and Neowise, we can figure out it's come from within our solar system and we can roughly work out from where it came and then where it's going back to.

• 11:00Neil deGrasse Tyson?

  All right, so in other words, if you calculate in orbit and it turned out to be infinity. Then it's never coming back and it was an interloper, right?

• 11:08Natalie Starkey?

  Yeah.

• 11:09Neil deGrasse Tyson?

  But you calculate the orbit and there's an actual number that comes out of that equation. What, six or seven thousand years, right?

• 11:15Natalie Starkey?

  Yeah.

• 11:16Negin Farsad?

  Wait, and it's just hanging out in this spot?

• 11:21Natalie Starkey?

  No, what, neowise? No, it's always on this orbit. So it's, some of them stay out in the outer solar system. But then occasionally, comets get kind of bumped into the inner solar system. Because they might have interacted with a big planet and that kind of orbited past and kind of threw them off their happy orbit. And then threw them towards the sun, essentially. Because the sun is really, really big. And so it's got tons and tons of gravity.

• 11:41Negin Farsad?

  I've heard, yeah.

• 11:42Natalie Starkey?

  So it pulls down.

• 11:47Negin Farsad?

  Gossip on the streets is, the sun's real big.

• 11:52Natalie Starkey?

  It's actually 99.9% of the mass of the solar system, right?

• 11:55Negin Farsad?

  I was just gonna say that, but thank you for saying that.

• 11:58Natalie Starkey?

  I could see you, I could see you thinking it.

• 12:02Natalie Starkey?

  So it pulls everything towards it. And so that's what happens with this comet. If it gets knocked out of its orbit, it then kind of comes hurtling towards the sun. They don't always go very close to the sun. They're still some distance away. And but if they get too close, they can get heated up so much that they just disintegrate completely, which has happened quite a lot of times. But this one was safe. It didn't go too close and it managed to kind of skirt around the sun. And it's going back out now. It's on its way back out to the outer solar system.

• 12:28Neil deGrasse Tyson?

  Alright.

• 12:28Negin Farsad?

  Alright, well, question numero dos comes from, also from Patreon. Ari Maude says, why is it comets don't orbit in a circular orbit like the planets do, but instead have a very elongated orbit, even though they all orbit the sun? Shouldn't a comet orbit like the planets, though way out in the Oort Cloud? Uh, you mentioned the Oort Cloud just now. By the way, who names these clouds and stuff? Because why isn't it named like Brad or Larry or something? Like, why do they all have?

• 13:04Natalie Starkey?

  These like, you know, science nerd names. I think the Oort Cloud was named after Jan Oort, is that correct?

• 13:10Neil deGrasse Tyson?

  Yes, it is, yes.

• 13:12Natalie Starkey?

  So it's named after usually the person that discovers them. So if you discover something awesome, then you know, you get to put your name to it quite often, which is really nice. That's cool.

• 13:19Neil deGrasse Tyson?

  Or, wait, or just I can add, if out of respect for you, if you make the discovery, then other people talking about your research paper will then coin that term. So Jan Oort did not say, "I've discovered the Oort Cloud." He didn't say that in his paper. He just did a calculation and showed there are all these comets that come in from very long orbits and they don't spend much time here. But if you look at the gravity of the situation, when you're far away from the sun, you're moving slowly. So then he did some math on this and figured there must be a place out there that has billions of comets. And those, and all, in all directions around the sun. And then that paper gets published and everyone said, "Hey, there's this cloud of comets that Jan Oort hypothesizes."

• 14:03Neil deGrasse Tyson?

  And it became the Oort Cloud at that point. Yeah. So how come they're not circular orbits, Natalie? What's up with that?

• 14:09Natalie Starkey?

  So, okay, so most of the Oort Cloud comets are just sat out there and they're basically forming this shell around the solar system. So if you imagine all of the planets and the asteroids, they all sit in a plane. And that's, that's where we all kind of circle around the sun. They're all in the same plane, pretty much anyway. And then the coip about comets are all also in that plane. But then the Oort Cloud comets, because they're so far away, they're not kind of bound to the solar system by the gravity in the same way that all the planets are. So they just form this shell. And that's pretty much how we know they're there. We've never been there, we've never directly observed them in the Oort Cloud. But sometimes when they come into the inner solar system, they get diverted in, they end up on this very kind of elliptical orbit

• 14:52Natalie Starkey?

  that brings them into the, around the sun, much closer. And that's how they end up on these. And that's how we know they're there, because they kind of come and visit us and then they disappear again out to their home in this shell around the solar system.

• 15:03Neil deGrasse Tyson?

  Are you suggesting that if all comets, in fact, did have circular orbits, we would never know they were there? Because they would never come closer to the sun rendered visible by the by the heat of the sun.

• 15:17Natalie Starkey?

  Yeah, I mean, definitely the alt cloud ones, of course, with the Kuiper Belt, we've now been there because we've had, we had the Voyager missions have gone through the Kuiper Belt now, and then we've had the New Horizons NASA mission that went to visit Pluto, which is actually a Kuiper Belt object, it's not a comet, but it's this big dwarf planet sitting out in the Kuiper Belt.

• 15:37Neil deGrasse Tyson?

  Negin, those are fighting words. She just said that casually. Did you hear that, Negin? Pluto, yeah, it's a Kuiper Belt object, that's all, it's in the Kuiper Belt.

• 15:45Natalie Starkey?

  I know, it's a dwarf planet, it's a dwarf planet.

• 15:48Negin Farsad?

  We've all been put on notice.

• 15:50Neil deGrasse Tyson?

  Yes. That just slipped out of her mouth, I just want you to know. Okay.

• 15:57Natalie Starkey?

  The great thing about New Horizons is it went to look at another object in the Kuiper Belt, so we got to see this icy object that's sitting out there. So we are actually now getting out there and visiting these things and seeing them in their home, we don't have to wait for them to come to us. But those missions are really tricky, because by the time you get out there, you're going to be traveling really fast away from the sun, and so you don't get a very long time to look at these objects. We just literally zoomed past Pluto and took a million images whilst we were there, and they're still being processed. We don't get long to look at these, it's really hard to enter into orbit around one of these things that's so far away, but we are going there now.

• 16:31Neil deGrasse Tyson?

  Wait, but so would you say then that most of the objects in the Kuiper Belt are on roughly circular orbits, and so we'll never see them unless they get jostled and set loose and plunge down back towards the sun?

• 16:44Natalie Starkey?

  Yeah, I think, you know, that's fair to say, because there's so many millions of them out there, and there are, we do get what we call near earth comets, which are the ones that are diverted towards the sun and come and visit us, but they're not that frequent, like, we have quite a few of them, but it doesn't happen that often that, you know, we're gonna need to worry about it too much.

• 17:02Neil deGrasse Tyson?

  So Nagin, the near earth comet, that's code for comet that could one day render us extinct.

• 17:08Negin Farsad?

  Oh.

• 17:09Neil deGrasse Tyson?

  Just want to clarify that.

• 17:11Negin Farsad?

  It's funny, because it seems like such an innocent term, and yet it's so deadly and horrifying.

• 17:19Neil deGrasse Tyson?

  Yeah, yeah. It was a near earth object that took out the dinosaurs, it came really near the earth.

• 17:27Negin Farsad?

  But I was half expecting you to say that the reason comets go in sometimes these oval shapes or whatever is because of Russian trolls. You know what I mean? Like, they're... Russian trolls can be attributed with a lot right now. And this might be one of them. I'm just throwing that out there. I want you to look into it.

• 17:47Neil deGrasse Tyson?

  We'll get top people, top people working on that right now. We have time for one more before we take our first break?

• 17:54Negin Farsad?

  Okay, and let's go to... Ooh, I love this question from Julia Casey, also from Patreon. She writes, "What unanswered questions about comets do you most want to see answered in your lifetime?"

• 18:11Natalie Starkey?

  Okay, that's a great question. So I think one of the really hot topics at the moment is trying to figure out whether... What the role that comets... What was the role that comets played in life on Earth? Because we don't know where we came from. We don't understand how life got here, and we don't understand how it started on Earth. We also don't understand where all our water came from, and these two things are really linked. We think we need water to make life, and we think we need water to sustain life on a planet or anywhere. But we don't understand where all these things came from. And it could be that comets and/or asteroids delivered the building blocks for life and also water to our planet in the past. We know they collided with us about four and a half billion years

• 18:55Natalie Starkey?

  ago. There were a lot of collisions of comets and asteroids into our planet. They brought all their goodies with them, and some of those goodies were organic material and a lot of water. So it might be that they delivered the building blocks for life, and then we need to understand how then we got life. Because it's not good enough to just say, "Oh, there's organic matter. We have life," because it's not that simple. We don't understand that next step in science of how we produce organisms like us.

• 19:21Neil deGrasse Tyson?

  So Natalie, you have unique expertise coming from a volcano, a volcano background, where we know they put water into the atmosphere. And now you're thinking about comets. So you could have the package of how to make all the water we've ever had.

• 19:34Natalie Starkey?

  Well, it's, yeah, maybe. Okay, so, yeah, volcanoes release a lot of water. They release a lot of gases into the atmosphere. Some of them good, some of them bad, but they don't actually have a bad negative effect on the climate as such. But the problem is, we don't know where that water came from within the Earth. So volcanoes erupt out material from inside the planet. And so the material that's inside the planet has to have been there either from the start, when the Earth formed, or it was delivered later on and incorporated into the inside of the planet, so that it could then be erupted out. Now, we may have started with all our water. When our Sun formed, and we formed all the planets and all the comets and asteroids around the Sun, it might be that we had all our water from the beginning, that we're actually, we've got interstellar water.

• 20:17Natalie Starkey?

  So our water might actually not be basically from our Sun. It might have come from interstellar space, which would be really, really awesome to think we're drinking water that's older than our Sun. But we just don't know, because the Earth was really inhospitable when it first formed. It was boiling, it was just a molten ball of magma. So it's hard to understand how we might have maintained water within that really hot blob of magma, because it probably would have all boiled off. So this is why scientists sometimes say, okay, maybe we brought that water in later on. Maybe it came from these asteroids that have a bit of ice on them. Maybe it came from these comets, which are very icy. But we just don't know. So that's one of the major questions we're trying to answer at the moment, where it all came from.

• 20:55Negin Farsad?

  And can Britta filter water that's older than the Sun? Is another question. This is, but I would love for you to figure that out, that like, the explanation of life on Earth, which is like, just a small answer to that question. Because then it explains everything, like sloths, why are they such a weird animal? And cargo pants, why? Like, it literally then explains everything. So you can be holding the key.

• 21:24Neil deGrasse Tyson?

  Everything, the key explainer. We've got to take a quick break, and when we come back, we will return to my co-host, Negin Farzad, and my special guest, Natalie Starkey, comet expert, when we return.

• 21:53Neil deGrasse Tyson?

  We're back, StarTalk Cosmic Queries. My co-host, Negin Farzad. Negin, you have a Twitter handle, Negin? You want to tell anybody?

• 22:01Negin Farsad?

  Yes, it's Negin Farzad, N-E-G-I-N-F-A-R-S-A-D.

• 22:05Neil deGrasse Tyson?

  Okay, it's just your name?

• 22:07Negin Farsad?

  It's just my name.

• 22:08Neil deGrasse Tyson?

  Okay.

• 22:10Neil deGrasse Tyson?

  I thought, when I said you have a Twitter, yes, I do. Here it is. It's Negin Farzad.

• 22:15Negin Farsad?

  So unexpected. So unexpected. It's my name.

• 22:19Neil deGrasse Tyson?

  I was ready for some other thing. I don't know why.

• 22:23Negin Farsad?

  I know. I really set you up for like, "It's fizzydoo43." You know, no, it's just my name.

• 22:29Neil deGrasse Tyson?

  Well, the real Negin Farzad, because so many others have stolen it. And Natalie, Natalie, are you also on Twitter?

• 22:36Natalie Starkey?

  I am, yes. Yeah, @starkystardust. So, yeah, my name, Starkey.

• 22:41Neil deGrasse Tyson?

  See, Negin, that's how you do that. Negin, that's how you do that, okay?

• 22:46Negin Farsad?

  Taking notes.

• 22:47Neil deGrasse Tyson?

  Starkey Stardust. Okay, so we're in Cosmic Queries mode, and we're talking about comets, of course, inspired by the recent appearance of comet Neowise in the sky. So, what's up next you have there?

• 22:59Negin Farsad?

  Up next, we have a question from Twitter, @saltsea83 asks, "Would you expect to find amino acids on Neowise? And could the Neowises of the universe be the life distributors?" Which, you kind of mentioned a little bit about that before.

• 23:14Natalie Starkey?

  Yeah, yeah, we touched on this in the last question. But actually, yeah, we're getting a bit more detail now. So, yes, we know that we've got amino acids on comets. So, I would very much expect comet Neowise to contain amino acids. So, we've now discovered them on two comets, which is pretty much the only comets we've studied in detail in space. The first one was comet Vilt II, which was visited by NASA Stardust, and they collected samples to bring back to Earth. And they found the amino acid glycine in it. Now glycine is the most simple, the most simplest amino acid. But it's there, so that's very exciting. Now, we corroborated that finding with the Rosetta mission, which is a European Space Agency mission, and it went to comet 67P.

• 23:57Natalie Starkey?

  But it was on the surface of the comet, it actually put a lander down onto the surface and it analysed all sorts of things, bits of dust and gas that were coming off the comet and it also found amino acids on the comet, again glycine. So we know we have them, we know comets collide with the planets and so they would have bought their inventory of amino acids, possibly other amino acids as well, we haven't found them yet but they might be there, they brought them to our planet in the past. So there's every chance that they did deliver life here, what we would call life in inverted commas, but obviously to go from amino acids to complex organisms is a really big step that we don't currently understand.

• 24:33Neil deGrasse Tyson?

  So Natalie, what you're saying is we were two for two in the comets that we could have known whether they had amino acids, so we're saying we're good with that.

• 24:41Natalie Starkey?

  Yeah, I think it's safe. And it's that we've found amino acids in asteroids a lot, so meteorite samples that are rocks that come from asteroids and land on our planet, or they can come from other planets as well, but the asteroid or meteorites also have tonnes of amino acids. In fact, in one particular asteroid sample, we found more amino acids than we have on our planet. So there's more variation in space than we need to account for all the life we have here.

• 25:07Neil deGrasse Tyson?

  You mean more kinds of amino acids?

• 25:09Natalie Starkey?

  Yeah.

• 25:10Neil deGrasse Tyson?

  Whoa. So life elsewhere could just have, could be more interesting than we are.

• 25:16Natalie Starkey?

  It might just rely on different, you know, bundles of amino acids to make life. We have no idea, we absolutely have no idea, but they're there. So that's the great thing, we have it, we've got the evidence that they're all over the solar system, but now we've just got to understand that next step of how we get life.

• 25:31Neil deGrasse Tyson?

  So Negin, that's the name of your next book, How to Make Aliens Laugh.

• 25:38Negin Farsad?

  Wait, so amino acids, I have a multivitamin that contains amino acids. Is it that same amino acids that you're talking about?

• 25:49Natalie Starkey?

  Yeah, I think it's...

• 25:49Negin Farsad?

  Like it's all the same?

• 25:50Natalie Starkey?

  I've never really looked at the multivitamin, what is in it, but yeah, I guess so.

• 25:57Negin Farsad?

  I mean, because it gives me good, you know, nails and hair, so... So yeah, so comets have great updos is basically what's going on.

• 26:07Neil deGrasse Tyson?

  Yeah, so Natalie, what's gonna happen is Negin's gonna visit the meteorite hall of the museum. She's in court licking the meteorites, that's what she's gonna start doing.

• 26:17Neil deGrasse Tyson?

  Trying to get her vitamins and minerals.

• 26:18Negin Farsad?

  No need to buy these supplements anymore. Just go lick the meteorite. That's an excellent point, Neil.

• 26:24Neil deGrasse Tyson?

  Negin, step away from the meteorite. Okay, and just before the next question, Natalie, could you tell me how NeoWise got its name?

• 26:35Natalie Starkey?

  Oh, yeah, that's actually a really interesting topic. I mean, I could talk about this for hours, but I won't. I'll try and do the short version.

• 26:41Neil deGrasse Tyson?

  Maybe the 30-second version.

• 26:44Natalie Starkey?

  Comets are generally named after the people that find them, or in the case of NeoWise, the telescope that found it, and it's called NeoWise. It's in space. It's a space telescope. So it's probably a group of people working on it. So we couldn't just give it one name, but previously, it would have just been one person looking through a telescope, and they found the comet, and they got to name it after themselves. So that's why they tend to have, you know, like Halley's Comet and all this, or it was Edmund Halley. But they also have a really boring designation. So it's also called C/2020F3, which tells you a little bit more about the type of comet. So the C means it's non-periodic, so it doesn't come around the sun very often. It's more than 200 years it takes to go around the sun.

• 27:25Natalie Starkey?

  The 2020 tells you the year it was found or discovered, and then the F3 tells you a little bit more about the exact month that it was discovered. So it tells you it's the end of March that it was discovered, and it was the third comet at the end of March to be discovered. So it tells you tons of information, but we tend to just call it NeoWise because it's much friendlier.

• 27:44Negin Farsad?

  I think you're underselling it a little bit, because C/2020/F3, I think, is going to be a very popular baby name coming up. Just wait, it'll trend.

• 27:56Neil deGrasse Tyson?

  Born or conceived under the comet. So Natalie, actually, Edmund Halley didn't discover Halley's Comet.

• 28:06Natalie Starkey?

  Really?

• 28:07Neil deGrasse Tyson?

  No, he did not.

• 28:08Natalie Starkey?

  Okay, there we go. I'm learning. Honestly, I always learn from you, Neil, because... You're on the brain here.

• 28:14Neil deGrasse Tyson?

  Yeah, what what he did was he took Newton's new equations of gravity and applied it to a comet that was in the sky and noticed that it was the same comet that had come around in previous records. Because now we can understand orbits, you can now think of comets not as singular objects, but as and so so but as recurring visitors to the inner solar system. So using that, he made a prediction of when it would come again.

• 28:45Natalie Starkey?

  Okay.

• 28:46Neil deGrasse Tyson?

  And so everyone just waited with with, you know, bated breath. And there it was, it came right when he said, right where he said it would come. And from then on, it was named after he was long dead by then, though. That's what what had happened. So that's a little cool fact.

• 28:59Natalie Starkey?

  It's due back in like 2060, I guess. So, you know, I hope I'm still around to see that.

• 29:04Neil deGrasse Tyson?

  Yeah, 2060, yeah, I think that is because it was 1986, it's every 75 years or so.

• 29:09Natalie Starkey?

  Yeah.

• 29:10Neil deGrasse Tyson?

  Right, right, cool. So Negin, you got another question?

• 29:13Negin Farsad?

  We have another question. It comes from Instagram. Is it possible to measure the rate at which a comet loses its mass as it travels across the solar system?

• 29:23Natalie Starkey?

  Yeah.

• 29:24Neil deGrasse Tyson?

  And let me add to that, Natalie. If you do that calculation, can you tell us when it will disappear completely?

• 29:31Natalie Starkey?

  Okay, so the answer to both these questions is no. Well, not there's no simple way to do this, but we've we've done it sort of once, really. We've done it with the Rosetta mission, that European Space Agency mission. And the only way we could do it with that mission is because the orbiter and the lander were with the comet the whole time. So they kind of approached it when it was around the orbit of Mars, Jupiter kind of place. They then stayed with that comet the whole way past the sun and then came out the other side. So what they were able to do was look at the processes that were happening as this comet was heated up and its ices were sublimating into space and it was experiencing that very hot environment near the sun. And as it came out the other side, and they could measure how much material was coming off it.

• 30:13Natalie Starkey?

  And what they estimated is that about a meter of the surface of the comet was lost during that orbit around the sun. That comet's about three by five kilometres, so a similar kind of size to comet NeoWise, but there's so many factors that will control how much it loses. It will depend on how much volatile material it has within it, the stuff that that streams off into space. It'll depend what exactly is its composition, how much ice it has compared to dust. It'll depend on how close it goes to the sun. There's so many factors that will affect that, that we couldn't simply apply that one metre rule to every comet that goes near the sun, because they'll all be different. But it gives us a good idea for that particular comet, that they do lose a lot of material, and that's, you know, a huge amount. So every time they go via the sun, that happens.

• 30:58Natalie Starkey?

  And so eventually, they die. We kind of say that they die. They don't have any volatile material left, the ice is all gone, so they've got no more material to lose as they go via the sun. And then they just, they don't have a tail anymore, they're no longer a comet, really. So, but it's hard to say how long that's going to take and how many orbits that takes to happen.

• 31:16Negin Farsad?

  My takeaway from this is that comets are always dieting, and that basically body shaming is happening in the solar system in a way that I had no idea, and I am not on board with it.

• 31:31Neil deGrasse Tyson?

  Yeah, losing a metre, that's, that's, that's a...

• 31:35Neil deGrasse Tyson?

  So Lily, the comet is being flayed by the sun. That's, that's, that's sad.

• 31:41Natalie Starkey?

  I know, I know, but then we wouldn't see them otherwise, because unless that process happened, as comets kind of reached it orbit around Jupiter, and that's when they start to get heated up, and that's when they'll start to produce what we call this coma, which is the, kind of the atmosphere that surrounds that rocky nucleus that makes up the comet. So they start to get heated up, and the ice within them, there's lots of different types of ice in a comet, it could be water ice, carbon monoxide, carbon dioxide, methane, ammonia, lots of different types of ice.

• 32:11Negin Farsad?

  Like the big, the big cubes they use in bars?

• 32:14Natalie Starkey?

  Yeah.

• 32:15Negin Farsad?

  Is that in there too?

• 32:16Natalie Starkey?

  There is, so common, yeah, we've got dry ice, because that would be the carbon dioxide stuff. So basically, they all get sublimated, which means they turn from solid to gas at different stages as they're going towards the sun. The first ones come off is gen- Carbon monoxide and that kind of glows blue. So if you often see images of comet neowise, they've got this kind of blue halo around the comet nucleus. And that starts to then stream off into the tail, that material. And so that's actually just the comet losing its mass and that all that material is just streaming out behind it. Along with dust particles that are coming off at the same time. So it's it's kind of can be quite a violent environment on the surface of the comet. As different portions of it get heated up differently and then jets of gases can shoot off.

• 33:01Natalie Starkey?

  And it can be quite crazy.

• 33:03Neil deGrasse Tyson?

  So Natalie, everything I know about that, I I learned from the movie Armageddon.

• 33:10Neil deGrasse Tyson?

  When they landed on the surface of the comet and it rotates into the sunlight. And then, you know, geysers start popping out and yeah.

• 33:18Natalie Starkey?

  Yeah, I don't want to say that was the only accurate part about that movie. I don't even think it was that accurate, but hey, yeah, I'm glad you have a mental image at least.

• 33:26Neil deGrasse Tyson?

  I do, I do. So Negin, what else you have?

• 33:29Negin Farsad?

  Okay, and we also have from Twitter. Um, oh, hello from Cape Verde, which is such an exotic location to be sending a message from.

• 33:42Natalie Starkey?

  Volcanic islands, aren't they?

• 33:44Neil deGrasse Tyson?

  Nice. Yeah, I think so too.

• 33:46Negin Farsad?

  It's like my dream to go visit. My dear friends, theoretically, can we harvest water from asteroids and comets to solve water crises and famines here on Earth? And if so, wouldn't that seem more important slash practical than starting a colony on Mars?

• 34:01Natalie Starkey?

  No.

• 34:02Neil deGrasse Tyson?

  And before you get to that, Natalie, let me just say, we had an entire live StarTalk live program on water. Not only on Earth, but in the solar system. And I had not fully appreciated how much rarer potable fresh water is becoming on Earth.

• 34:20Natalie Starkey?

  Yeah.

• 34:20Neil deGrasse Tyson?

  You know, water, water all around and not a drop to drink. So what is the nature of the water on comets? And why can't we just lasso one and bring it in? Make a lake of it and dip in our straws?

• 34:30Natalie Starkey?

  Well, yeah, the thing is, first of all, obviously, we're going to be much better placed looking after our own water supplies, making fresh, clean water for ourselves and not polluting the rest of our planet. And having a lot of salt water is a problem because obviously we don't want to drink salt water. Now, when we go into space, there are other moons and stuff that have water on them, but it tends to be salty water. That's good for life and that life can survive in there, but it's not stuff that we want to drink. So sure enough, if we were to travel out into space and we wanted to go and, you know, live on Mars, not sure that's going to be a good idea. But anyway, if we did, we would need water and there's no water on Mars that we don't think there's much anyway. There might be some in the subsurface, but it's, we don't know.

• 35:15Natalie Starkey?

  So we could kind of travel by a comet on the way and, and get some water. We could just melt some of that comet, separate out the water ice from, you know, all those other types of ices that it contained. And sure enough, we could use that in space. And we do think that that is one of the ways we might be able to explore further into the solar system. But it has its problems. We, it just, it's not going to be very easy to do, just kind of fly by a comet and grab some water. It's not that simple. But it's definitely not something we'll be doing to bring back to Earth. It's not going to be practical to transport water back to our planet. And even though there's a lot of it in space, we're better off looking after our own water here.

• 35:53Neil deGrasse Tyson?

  So there's an interesting corollary to that because it still costs NASA about $10,000 a pound to put a payload into space. So if I'd launched you and you want to drink 16 ounces of water, if I set up a mining colony that mines frozen water from asteroids and comets, melts it, then I sell it to NASA, but for on-space activities. And I'll sell it to NASA for $7,000.

• 36:21Natalie Starkey?

  Yeah.

• 36:22Neil deGrasse Tyson?

  I can do that. And then if it gets cheaper, I'll sell it for 5,000, whatever. But I can imagine a future, however distant, where the water that we do harvest from comets goes to other activities in space, rather than, I agree, it'd be impractical just to bring it back to Earth.

• 36:39Natalie Starkey?

  Yeah, and at the moment, anybody that goes up and grabs an object in space, like an asteroid or a comet, can own, I think, pretty much, American citizens, anyway, can own whatever they find in space. I have a feeling the rest of the world is catching up with those laws. So yeah, you could do that. If you could go and mine a comet or asteroid, you can, for sure, then sell it, whatever materials you get from it, to whoever wants them.

• 37:01Neil deGrasse Tyson?

  That's been an American rule ever since the beginning. We find it, and then it's ours.

• 37:07Negin Farsad?

  How the country was built.

• 37:10Natalie Starkey?

  The really cool thing about water is that you can also use it as propulsion for rocket fuel. So if you can split the hydrogen and the oxygen out of the water, water being H2O molecule, and the hydrogen and the oxygen, then you can use that as propulsion as well. So it's not just for humans living, but it's also to get further into space. Because, as you said, launching anything off our planet is incredibly expensive because we have a lot of gravity. So if we can get our fuel in space without having to take it with us from the Earth, that's a real bonus as well.

• 37:41Neil deGrasse Tyson?

  Yeah, excellent. All right.

• 37:45Negin Farsad?

  And...

• 37:46Neil deGrasse Tyson?

  Negin.

• 37:47Negin Farsad?

  We also...

• 37:48Neil deGrasse Tyson?

  You got more for us?

• 37:48Negin Farsad?

  We've got a question from Instagram, from @GabrielWakim. "How do different chemical compositions change the color of the comet?"

• 37:58Neil deGrasse Tyson?

  Nice question, because I've seen pictures of the comet, and there's all these beautiful colors in it. I want to know where that comes from, except we have to take a break.

• 38:08Neil deGrasse Tyson?

  When we come back, we will all learn from Natalie Starkey how comets get their colors on StarTalk.

• 38:24Speaker 03

  We'd like to give a Patreon shout out to the following Patreon patrons. Matthias Mancini and Sandra Balliger. Thanks so much for being our bright shining star. Without you, we couldn't do this show. And if anyone else listening would like their very own Patreon shout out, please go to patreon.com/stargtorkradio and support us.

• 38:50Neil deGrasse Tyson?

  We're back. StarTalk, Cosmic Queries, Comets. I've got Nagin Fassad, my co-host, and Natalie Starkey, who's our resident comet expert, except she's in the UK right now. So she's a resident of somewhere. Yeah, so Nagin, someone had just asked about comet colors. Is that right?

• 39:10Negin Farsad?

  That's right. They asked, um, what, like, how do different chemical compositions change the color of the comet?

• 39:17Neil deGrasse Tyson?

  So how does a leper get its spots? And how do comets get their colors? See, this should be in the same book.

• 39:23Natalie Starkey?

  Yeah, that's a great question, because it's one of the ways we can figure out what comets are made of, because we can look at their colors as they come into the inner solar system, and it tells us what is literally coming off their surface, which ices are sublimating and turning from solid to gas as they they get hotter. So I mentioned earlier that the first gas that tends to come off is carbon monoxide, and that glows blue. Neil can probably explain the physics reason behind all the ions interacting and why that glows blue. Do you want to?

• 39:52Neil deGrasse Tyson?

  No.

• 39:55Natalie Starkey?

  But it glows blue, let's just say. There's no interaction with the physics.

• 39:58Neil deGrasse Tyson?

  No, no, I can tell you. No, I can tell you. So these these molecules have certain sort of energy states that they exist in. And if they're fed another energy source, they can, you can kick electrons off of them, or you can bump them up into a higher energy state, and then they release that energy back to you. But in a very specific part of the spectrum. And then you so and different compounds, different, different molecules, different atoms have different colors corresponding to what their energy levels are. So it's it's not deeper than that. And that's going on all the time. So yeah, so go on.

• 40:35Natalie Starkey?

  You see, this is that's the exam question, isn't it, that I should have. My high school chemistry teacher will be like, oh, Natalie, you should know this stuff.

• 40:43Neil deGrasse Tyson?

  By the way, do you remember the glow in the dark frisbees? You know, you you'd put it under a light and then you'd throw it. Do they play frisbee anymore? It it glows this kind of pale green. Well, when you put it under regular light and it bumps up the energy levels. And then when you take it away from the light, the the electrons descend and emit this green light.

• 41:04Natalie Starkey?

  Yeah.

• 41:04Neil deGrasse Tyson?

  Corresponding to the material that's in the in the in the frisbee itself. So and it doesn't do that forever, right? You only get to play with it for 10 or 15 minutes before you don't see that signature at all. But the comet is constantly getting stoked by the sun. So you get these colors to stay. So go on.

• 41:20Natalie Starkey?

  You can sometimes get a green color, which I think is related to elemental carbon because we know there's a lot of carbon in comets. The dust particles tend to be made up of carbon, hydrogen, oxygen, and nitrogen particles. So all the stuff for life, it's brilliant. And you can also sometimes get a red tail, which is so with with comets, you tend to have two main tails. The first one is is made of dust and that can be quite diffuse. It tends to be sort of either white, gray, kind of yellow colored. You get the second tail, which is the ion tail, which is these gases that have come off, and that's tends to be blue or greeny colored. And then sometimes there's this sodium tail, which is red. And I think actually it was seen with comet Neowise. So there were three different tails coming off this comet.

• 42:02Natalie Starkey?

  So you've got the comet traveling towards the sun and these tails all face away from the sun, basically.

• 42:08Neil deGrasse Tyson?

  Right, so tail is a misnomer on its way out of the solar system.

• 42:11Natalie Starkey?

  Hmm.

• 42:12Neil deGrasse Tyson?

  Out of out of the inner solar system, right? If it goes out tail first.

• 42:15Natalie Starkey?

  Yeah.

• 42:15Neil deGrasse Tyson?

  We think of tail as something that trails.

• 42:17Natalie Starkey?

  Yeah. Exactly.

• 42:18Neil deGrasse Tyson?

  But it's only trailing on its way in.

• 42:20Natalie Starkey?

  Yeah, the tail ends up ahead of the comet, or the tails.

• 42:23Neil deGrasse Tyson?

  Ahead of the comet, yeah.

• 42:24Natalie Starkey?

  But they're not all in line with each other, because obviously the dust and the ion gases, they get distributed differently and they react differently to the gravity of the sun and the solar wind and everything. So they end up being separated, and that's how you can see them. And, I mean, some of the images that people have got of this comet have been absolutely amazing.

• 42:39Neil deGrasse Tyson?

  Aren't they beautiful? Oh, yeah. And everybody's got a great camera, and you don't need full telescopes to do this anymore. Just a camera with a good lens.

• 42:46Natalie Starkey?

  Yeah.

• 42:46Neil deGrasse Tyson?

  Not like the old days. I sound like an old man.

• 42:49Natalie Starkey?

  (laughing).

• 42:49Neil deGrasse Tyson?

  Off my lawn! My day! We used to...

• 42:55Neil deGrasse Tyson?

  So Negin, can we go into lightning round?

• 42:58Negin Farsad?

  Lightning round.

• 42:59Neil deGrasse Tyson?

  Yeah, actually, it's not up to you, it's up to Natalie to answer questions.

• 43:02Natalie Starkey?

  Okay, I'll try my best.

• 43:03Neil deGrasse Tyson?

  Yeah, let's see. Pretend you're on the evening news and they just want soundbites.

• 43:07Natalie Starkey?

  (laughing).

• 43:07Neil deGrasse Tyson?

  Okay, so this is your soundbite quiz, okay? So Negin, what do you have?

• 43:12Negin Farsad?

  All right, Rob Kirsten from the Netherlands writes on Instagram, "Let's say a com-

• 43:17Neil deGrasse Tyson?

  Oh, by the way, by the way, Jan Oort was from the Netherlands.

• 43:20Negin Farsad?

  Oh, there it is.

• 43:21Neil deGrasse Tyson?

  Just, the Dutch have had a long, in the 20th century, very long and proud history of participating in cosmic discovery. Just thought I'd give a toss-out to the Dutch. But go on, okay?

• 43:35Negin Farsad?

  "Does comet Halley always have the same tail color every time it comes around the sun? The chemical composition burns, but can a comet gain other chemical compositions on its way to us?"

• 43:47Natalie Starkey?

  Um, yes, so it'll, I think it should theoretically always glow the same color because it will have the same ices within it. But as they get depleted, I guess it could change color with each orbit of the sun, but it definitely isn't going to gain any material as it goes by the sun. It'll only be losing stuff.

• 44:03Neil deGrasse Tyson?

  Good short answer. Let me ask, could there be a layer below that's different from the layers above that then gets revealed as a new chemical signature?

• 44:10Natalie Starkey?

  Completely. We have no idea, because we haven't studied enough comets up close, and we haven't studied enough over the course of an orbit. So, yeah, we don't know. They could be completely different as they go, as you delve down into them. It's great, we have no idea. Lots to find out still.

• 44:24Negin Farsad?

  It's like a seven-layer nacho dip.

• 44:29Negin Farsad?

  More to discover. Okay.

• 44:31Neil deGrasse Tyson?

  Okay.

• 44:32Negin Farsad?

  We have from Oxford, comma, 20 on Twitter. How many?

• 44:37Neil deGrasse Tyson?

  Oxford, comma, 20. Oh, this is, we got a literate person here. Okay, let's do that.

• 44:42Negin Farsad?

  How many encounters with the inner solar system do comets from the Kuiper Belt and Oort Cloud get before they're totally steam cleaned and become plain old asteroids?

• 44:51Neil deGrasse Tyson?

  Oh, I like that.

• 44:52Natalie Starkey?

  So we had a similar question earlier, and actually, it's, again, we don't know. We don't really know for any individual comet, how long it's going to take for it to just die and lose all its ices. So we just have to study each one in detail, and then, once we see what it does on its first orbit, that we look at it, we've got to wait till it comes back and see how it reacts again. We really have no idea. But we have observed comets that are then dead. So we know that that can happen. But how long it takes for that to happen, we really don't know at the moment.

• 45:21Neil deGrasse Tyson?

  So when you say dead, you don't mean destroyed? You mean there's nothing to evaporate to render it visible?

• 45:25Natalie Starkey?

  Exactly. So they just end up as like a hunk of rock in the end.

• 45:28Negin Farsad?

  What I'm gathering from all of this is that comets are a really fickle lover. You know, you just don't know what they're gonna do, how they feel, you just don't know.

• 45:37Natalie Starkey?

  Exactly.

• 45:39Neil deGrasse Tyson?

  So Negin, keep going.

• 45:40Negin Farsad?

  All right.

• 45:41Neil deGrasse Tyson?

  Keep, keep, keep two more. We got like one minute left.

• 45:43Negin Farsad?

  Okay, we have two more.

• 45:44Neil deGrasse Tyson?

  And Natalie's on a roll. She's got, she's knocking these out. Okay, go.

• 45:47Negin Farsad?

  From RealTiredHours on Instagram, I want to know if comets orbit all the same direction in the same way planets do. And if not, what would it look like if two comets collided while visible from Earth with the naked eye? I want to know that, too.

• 46:02Natalie Starkey?

  Yeah, that would be so cool. Okay, so we've seen comets disintegrate when they go near the sun. I mentioned this earlier, when, you know, these things are very volatile. They, they are very fragile because they're made, they're basically a snowball with a bit of dirt in. So if they go too close to the sun, they can explode. And we have sort of seen that with a telescope before. But if two were to collide in space, well, it's unlikely to happen. But if it were to happen, we would basically see these things sort of collide and disintegrate. It might not be as exciting as you might think, because like, if you had two rocks colliding, because they'd probably just sort of melt into each other a little bit. But if they were to collide in the outer solar system, they're going pretty kind of, it's kind of quite far apart out there, and they're not kind of going

• 46:46Natalie Starkey?

  to hit each other with very much force. So if they were to collide way out in the outer system, we wouldn't really see much, or we wouldn't be able to see it happen anyway. But I don't think it would be very exciting.

• 46:56Neil deGrasse Tyson?

  Natalie, you're bumming us out. This was a great question. Now, you turned it into like, nah, it's not gonna be exciting.

• 47:02Negin Farsad?

  Yeah, like I was like, I was geared up for like the Macy's fireworks display and instead you're like, oh no, this is like the sad like Larry outside of Sheboygan doing fireworks off his roof, you know? That's what we're gonna see.

• 47:15Natalie Starkey?

  They're so fragile and I think nothing, like if, if they come into, they can collide with our planet and they have done in the past, but actually the only time we've ever kind of observed this happening, um, it, they kind of explode as they come through the atmosphere because they just can't maintain their shape, um, because they're just not consolidated enough, they're not held together very well. And they tend to explode in the atmosphere before they even reach the surface of the planet. So, yeah, I don't think it'd be very exciting.

• 47:40Negin Farsad?

  All right.

• 47:41Neil deGrasse Tyson?

  All right.

• 47:41Negin Farsad?

  Here's your last question.

• 47:42Neil deGrasse Tyson?

  One last question, last question, go.

• 47:44Negin Farsad?

  Last question is from dudespraya on Facebook. Is it possible for a probe to hitch a ride on a comet? Maybe an extra solar comet that'll leave the solar system?

• 47:53Natalie Starkey?

  Oh, lovely question. I like this one. So, yeah, of course, we've done this with the European Space Agency mission, the Rosetta mission, which I've mentioned a few times because it was just one of these groundbreaking missions to a comet. It landed, a little lander on the side of the comet and as I said, it followed that comet then as it went via the sun and came out the other side. Um, and it's still there. So this comet is now heading out into the outer solar system again and that little lander is still with it. And they even had an orbiter with that comet, which they basically crash landed onto the comet because they were like, we can't do any science now. There's no sun, we need sun to have our solar panels. What are we gonna do with this spacecraft? We'll just crash land it or decelerate it into the comet. So they're now with it. Now, if you did that with a comet like a Muammar and it was going out of the solar

• 48:36Natalie Starkey?

  system at great speed, then sure, you could then hitch a ride. You'd have trouble with power and it's very cold as you get away from the sun. So spacecraft don't really like that, but it is possible.

• 48:46Neil deGrasse Tyson?

  Let me add that it's not so much that you're hitching a ride, because if you matched speeds to the interstellar object, Amu Amua, then, once you match speeds, you don't have to attach to it, because you will have the exact trajectory that Amu Amua would have. So it's an interesting fact. It's not like you just hook it and then it pulls you along. It's you're matched, you've matched speeds. You're there. You are with the comet, whether you're touching it or not.

• 49:17Natalie Starkey?

  And that is physics. That's amazing.

• 49:19Neil deGrasse Tyson?

  That's just the physics of it. But Natalie, I think it's funny to think that we've got our hardware sitting on a comet with the Rosetta mission. So the next time it comes around, if it's jostled loose, there's like a spacecraft yanking it, getting jettisoned off the back of a comet.

• 49:37Natalie Starkey?

  And that's what they were worried about when the comet went via the sun. The lander may have just been thrown off into space if a big jet of gases had shot off the comet when it got heated up. So, yeah, it was a real, we had no idea what was gonna happen, because we'd never done it before. So, yeah.

• 49:50Negin Farsad?

  I am super prone to motion sickness, so the idea of hitching a ride on a comet just sounds horrifying to me. Just sounds like a vomit bag, a constant use of a vomit bag.

• 50:02Natalie Starkey?

  Yeah, they spit a lot as well.

• 50:04Negin Farsad?

  No, no, no, no, thank you.

• 50:06Neil deGrasse Tyson?

  You should be more worried about a jet spewing forth under you and then casting you back out into space, rather than just being on the comet and worried that you might need some drama.

• 50:20Neil deGrasse Tyson?

  So we gotta end it there. Negin, it's always great to have you. Always. It's the second time. Hope to see more of you as my co-host.

• 50:27Negin Farsad?

  So fun. I learned so much.

• 50:29Neil deGrasse Tyson?

  And your book, How to Make White People Laugh, crazy title. And even crazier podcast title, what is it again?

• 50:38Negin Farsad?

  Fake the Nation.

• 50:39Neil deGrasse Tyson?

  Fake the Nation. Good luck with those, and we hope to see you again. And Natalie, always good to see you. Keep it going. We'll look for you when you come back to New York.

• 50:48Natalie Starkey?

  Yeah.

• 50:49Neil deGrasse Tyson?

  And maybe we can arrange for another comet for you to talk about.

• 50:51Natalie Starkey?

  That would be amazing. Or an asteroid. I'll take any of them. We've got loads of missions coming up at the moment going to asteroids, so there's so much to talk about.

• 50:57Neil deGrasse Tyson?

  We wanna learn about those, definitely, definitely. So, thank you. And the title of your next book you're working on?

• 51:02Natalie Starkey?

  It's called Fire and Ice: Space Volcanoes.

• 51:05Neil deGrasse Tyson?

  Very nice, very nice, very nice. Okay. This has been StarTalk Cosmic Queries. Neil deGrasse Tyson, your personal astrophysicist. As always, I bid you to keep looking up.