Cosmic Queries: Comets and Asteroids with Dr. Amy Mainzer

Curious about comets? Anxious about near-Earth asteroids? Join us as guest host Dr. Amy Mainzer from NASA/JPL answers your Cosmic Queries with a little help from comic co-host Chuck Nice.

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.

• 0:21Speaker 01

  Welcome to StarTalk Radio. I'm your guest host today. My name's Amy Mainzer and I'm an astronomer from the Jet Propulsion Laboratory. And I'm here today with my co-host Chuck Nice.

• 0:32Chuck Nice?

  Hey Amy, how are you?

• 0:34Speaker 01

  I'm doing great. How are you?

• 0:35Chuck Nice?

  I am great. I am, I gotta tell you, I am better because you are here and you are so much better looking than Neil.

• 0:43Speaker 01

  Oh, thank you.

• 0:45Chuck Nice?

  Even though I miss Neil, I love him to death. Of course, he's off, uh...

• 0:49Speaker 01

  He's a busy guy right now.

• 0:50Chuck Nice?

  Yes, he is. Doing the cosmos. That's what he's doing right now.

• 0:53Speaker 01

  Yeah, he's gonna become Mr. Universe pretty soon.

• 0:55Chuck Nice?

  You know, and I'm sure that has been a dream of his for so long, to carry the title Mr. Universe. He actually can do that now.

• 1:02Speaker 01

  He actually can now.

• 1:03Chuck Nice?

  So let me ask you something. Before we, before we jump into the show, of course, we're doing cosmic queries where we have a bunch of questions that are taken from Facebook, the internet, Twitter, StarTalk.net, and any number of outlets where you might find the StarTalk brand. But before we get into that, tell me about Jet Propulsion Labs. And I know that's part of NASA, or is it part of NASA?

• 1:28Speaker 01

  Yeah, this is part of NASA. And the funny thing about the name is, there really is no jet propulsion that goes on there whatsoever.

• 1:34Chuck Nice?

  No jet propulsion at Jet Propulsion Labs?

• 1:36Speaker 01

  There is no jet propulsion at the Jet Propulsion Labs. It's a historical name.

• 1:39Chuck Nice?

  Right.

• 1:40Speaker 01

  And it's back from the early days of rocketry. And I guess they thought calling it the Rocket Spaceship Lab was a little too weird in science fiction at the time. So they called it Jet Propulsion.

• 1:49Chuck Nice?

  Jet Propulsion Labs.

• 1:50Speaker 01

  Yeah, sounded a little better.

• 1:51Chuck Nice?

  And now what do you guys do there for NASA?

• 1:53Speaker 01

  Well, mostly we do robotic space missions. So we explore the solar system and the rest of the cosmos with our robots, which are basically our eyes and our ears.

• 2:02Chuck Nice?

  Oh.

• 2:03Speaker 01

  Yeah, so it's great. I get to go explore the cosmos from the comfort of my couch, which I love.

• 2:10Chuck Nice?

  Your own little robot up there doing the work.

• 2:11Speaker 01

  Absolutely. Yeah. So I don't have to, you know, I can still eat donuts. I mean,

• 2:17Speaker 01

  it's a much better life.

• 2:19Chuck Nice?

  So you guys are, you're listening and watching the universe for us. You're like the NSA of the cosmos.

• 2:25Speaker 01

  Yes, except that we are not really interested in, you know, any sort of bad behavior, although we do like to look for things like potentially bad behaving asteroids. We do keep an eye on those with our robots.

• 2:36Chuck Nice?

  Very cool. Very cool. And you look familiar to me in a way. I, I feel like I may have seen you on the History Channel. I hope I'm not embarrassing you, but I got, is that true?

• 2:46Speaker 01

  Yeah, I did. It used to be on that. Yeah.

• 2:48Chuck Nice?

  Sweet.

• 2:49Speaker 01

  It was fun. It was really nice.

• 2:50Chuck Nice?

  Very nice.

• 2:51Speaker 01

  One thing about scientists, we love to talk about science. In fact, try to get us to stop talking about science.

• 2:56Chuck Nice?

  Well, that's good to know because that's exactly why we're here. And that's exactly what I got for you right now, which is a bunch of questions. And it is perfect for you because it's comets and asteroids.

• 3:06Speaker 01

  Oh, some of my favorite topics.

• 3:07Chuck Nice?

  So here, here, so let's jump right into this and um, let's start off with uh, Steve Bristo. How did the asteroid belt in our solar system come to be in orbit?

• 3:23Chuck Nice?

  And how did they come to be? Period. Where did they originate?

• 3:28Speaker 01

  Oh, the asteroids. They asteroids and comets are kind of like the leftover bits of junk. They were the remnants of what happened when our solar system first formed about four and a half billion years ago. Now I'm going to channel Carl Sagan here. Four and a half billion years ago.

• 3:44Chuck Nice?

  Wow. Okay.

• 3:45Speaker 01

  How's that?

• 3:46Chuck Nice?

  You sound a little Dr. Evil when you do it. Four and a half.

• 3:49Speaker 01

  Billion.

• 3:52Speaker 01

  Well, the thing about that is, is that all those years ago, there was a giant cloud of gas and dust. In the beginning, there was a whole lot of junk, a lot of gas and dust, and it collapsed under the influence of gravity. Eventually it formed a sun in the center. The stuff got hot enough and dense enough to ignite fusion. And the rest of it clumped into planets. Jupiter swept up most of the stuff because Jupiter is the biggest planet.

• 4:16Chuck Nice?

  So huge.

• 4:16Speaker 01

  Yeah, it's this whopping massive planet in our solar system. And then it forms. Saturn and all the other smaller planets. Well, the thing is, is they didn't quite clean up the mess they left behind.

• 4:26Chuck Nice?

  Gotcha.

• 4:26Speaker 01

  There's always a little bit of bits and pieces there left. And those little bits of kind of space debris, if you will. Those are what became the asteroids and the comets today. Things that formed a little further away from the sun where it was cold, really dark. Those are what formed the comets, the icy stuff.

• 4:43Chuck Nice?

  Right.

• 4:44Speaker 01

  And the stuff that formed closer to the middle, well, that's the rockier stuff. It was too hot for ice to form there. So that's how you get asteroids. Yeah.

• 4:51Chuck Nice?

  So right there is the difference between comets and asteroids.

• 4:54Speaker 01

  Yes.

• 4:55Chuck Nice?

  So one, big giant ice balls.

• 4:57Speaker 01

  Yep.

• 4:58Chuck Nice?

  And the other, big giant rock balls.

• 5:01Speaker 01

  Exactly. Space rocks versus space sort of icy rocky things.

• 5:05Chuck Nice?

  Okay.

• 5:06Speaker 01

  And now it's kind of a continuum. We find asteroids that sometimes masquerade as comets. And then we have comets that sometimes turn into asteroids. So there's kind of a weird, we used to think they were two totally different kinds of things. And now we know that there's kind of a gray area in between. Yeah.

• 5:22Chuck Nice?

  Kind of like actors who want to be music stars.

• 5:25Speaker 01

  Okay, so yeah, they're slashies, right?

• 5:27Chuck Nice?

  Right, there's actor slash dancer.

• 5:29Speaker 01

  Yes.

• 5:29Chuck Nice?

  Actor slash, you know, musician. I'm Kevin Bacon. I'm a big actor, but I'm also in a band with my brother. Like that type of dude.

• 5:38Speaker 01

  Exactly. Sometimes we have asteroids who are, well, sometimes we emit lots of gas and have, you know, comas that come off of us.

• 5:44Chuck Nice?

  Okay, thank God you were talking about the asteroids.

• 5:50Chuck Nice?

  You caught me, bud. You caught me off guard there, baby.

• 5:55Chuck Nice?

  Go ahead, though.

• 5:56Speaker 01

  So yeah, so sometimes these are, these are the slashies of the, of the, of the solar system. They're basically things that sometimes can cross the boundary between asteroids and comets.

• 6:05Chuck Nice?

  And comets.

• 6:05Speaker 01

  So that's right.

• 6:06Chuck Nice?

  So basically, these things have been here from the beginning of our solar system.

• 6:09Speaker 01

  Yes, that's right.

• 6:10Chuck Nice?

  And they're just basically remnants that are still kind of hanging around.

• 6:13Speaker 01

  Exactly.

• 6:14Chuck Nice?

  Like teenagers that will not move out of their parents' house.

• 6:17Speaker 01

  In, in fact, and they make a giant mess occasionally.

• 6:20Chuck Nice?

  Right.

• 6:20Speaker 01

  Sometimes they even crash into things.

• 6:23Chuck Nice?

  They really are teenagers.

• 6:24Speaker 01

  They are very badly behaved sometimes.

• 6:26Chuck Nice?

  Asteroids, the teenagers of the cosmos. All right, cool. Well, there you go, Mr. Bristow. There's your answer. So let's move on. That's a, that's a very good answer. I'm glad you said that. Here's another one from Twitter. Uh, EM at. Infinity X-91.

• 6:42Speaker 01

  Hmm.

• 6:42Chuck Nice?

  Okay, there's a handle for you.

• 6:44Speaker 01

  Hmm.

• 6:44Chuck Nice?

  How does a rock become a comet? So you told us about this gray area, so you know, this is a great follow-up question. How does a rock become the actual comet?

• 6:55Speaker 01

  Well, every now and again, we see some strange behavior in the asteroid belt between Mars and Jupiter.

• 7:00Chuck Nice?

  Mm-hmm.

• 7:00Speaker 01

  In fact, in recent years, we've seen asteroids that suddenly kind of explode or have like a big poof of dust come off of them.

• 7:06Chuck Nice?

  Mm-hmm.

• 7:07Speaker 01

  We think what happens is that sometimes they get hit by other asteroids.

• 7:10Chuck Nice?

  Okay.

• 7:11Speaker 01

  And it makes a mess and it looks like a comet.

• 7:13Chuck Nice?

  Ah.

• 7:14Speaker 01

  They're tricky. They masquerade sometimes.

• 7:16Chuck Nice?

  So they're masquerading as a comet?

• 7:18Speaker 01

  Yeah.

• 7:18Chuck Nice?

  They're not necessarily, so they don't really have the ice on them.

• 7:22Speaker 01

  Exactly.

• 7:22Chuck Nice?

  They just have the dust that's coming off of them like ice melting away.

• 7:27Speaker 01

  You got it.

• 7:27Chuck Nice?

  So it creates the appearance of a tail, but it's not really like a comet.

• 7:31Speaker 01

  And they are a big mystery. So that's one of the great mysteries of our solar system. There's always something new to learn, you know?

• 7:36Chuck Nice?

  Right.

• 7:37Speaker 01

  Sometimes asteroids act like comets.

• 7:39Chuck Nice?

  There you go.

• 7:40Speaker 01

  So...

• 7:41Chuck Nice?

  Oh, so I get it. Asteroids are the drag queens of the universe.

• 7:46Speaker 01

  Call RuPaul, yes.

• 7:47Chuck Nice?

  (laughing).

• 7:48Speaker 01

  And with that, it's time to take a short break. We will be right back.

• 8:10Speaker 01

  Welcome back. Here we are again on StarTalkRadio.net and I'm here with my co-host Chuck Nice. You can catch him on Twitter.

• 8:16Chuck Nice?

  That's right.

• 8:17Speaker 01

  At ChuckNiceComic.

• 8:18Chuck Nice?

  At ChuckNiceComic and I might as well return the favor because you are at Amy Mainzer and that's M-A-I-N-Z-E-R, Amy Mainzer, right?

• 8:28Speaker 01

  Yeah.

• 8:28Chuck Nice?

  On Twitter.com.

• 8:29Speaker 01

  It's a very good German name, yes.

• 8:30Chuck Nice?

  Yeah. And I understand you roller skate. That's something that we were talking about in the break.

• 8:33Speaker 01

  I do, I roller skate.

• 8:34Chuck Nice?

  And what is the purpose of that?

• 8:35Speaker 01

  Oh, it's because it's as unlike work as you can get, but it is also, it is very good exercise. That's what I tell myself.

• 8:42Chuck Nice?

  So not inline skating, actual roller skating?

• 8:44Speaker 01

  Oh, yeah. Old school quad skates, yeah.

• 8:46Chuck Nice?

  And do you, do you roll and bounce?

• 8:48Speaker 01

  I do, in fact, roll and bounce and...

• 8:50Chuck Nice?

  And do you have a giant like, uh, radio that you carry on your shoulder while you're doing it?

• 8:54Speaker 01

  Well, I'm actually very proud of this. Uh, my skate partner and I, we, uh, won the JPL Talent Show, the first annual JPL Talent Show. So I'm very proud of that.

• 9:02Chuck Nice?

  Sweet.

• 9:02Speaker 01

  It was, you know, it was the JPL Talent Show, so it's not exactly American Idol, you know?

• 9:07Chuck Nice?

  Right, I understand. Yeah, you gotta consider the competition, right?

• 9:10Speaker 01

  Yeah, but we roller skated for that, so.

• 9:11Chuck Nice?

  Sweet.

• 9:12Speaker 01

  That was good.

• 9:13Chuck Nice?

  Hey, well, let's jump back into our cosmic queries and, uh, we're talking about comets and asteroids, and we have, uh, called questions from all over the internet. And this one comes from Facebook, Jeff Turner, and he says, "Any concrete plans for launching exploratory missions to the Kuiper Belt?"

• 9:29Speaker 01

  Ah, okay, so the Kuiper Belt for folks is a region of, of icy bodies that are comet-like, and probably some of the, the origins of the comets are out there. And it's out really pretty far away in the solar system. So this is this leftover bits of stuff from the formation of the solar system. It's very cold, very far away.

• 9:47Chuck Nice?

  Right.

• 9:47Speaker 01

  Getting there is tough. Now, the thing is, we have a mission that NASA has launched a long time ago. I think it might even be nine years ago now. It's not going all the way out there, but it is going to Pluto, our favorite non-planet.

• 10:02Chuck Nice?

  Our favorite ice ball in the sky.

• 10:04Speaker 01

  Yes, and there are some plans, once this mission, which is called New Horizons, once it goes flying past Pluto, there may be a plan to see if there's a place it could go to visit in the Kuiper Belt. So we're just gonna have to see what comes up.

• 10:16Chuck Nice?

  Okay.

• 10:17Speaker 01

  But it is on its way, and it has got a long way to go.

• 10:20Chuck Nice?

  So, um, there's your answer, Jeff. Um, there are concrete plans, um, they're just somewhat tentative.

• 10:27Speaker 01

  Yeah, they gotta find the object first, that's the problem.

• 10:31Chuck Nice?

  Right.

• 10:31Speaker 01

  Yeah, it's actually tough. These things are so far away and they're super faint.

• 10:35Chuck Nice?

  Right.

• 10:35Speaker 01

  It's really hard to see them, so they're trying to find a place for, for New Horizons to go after the Pluto encounter.

• 10:40Chuck Nice?

  Right.

• 10:41Speaker 01

  So wish us luck.

• 10:42Chuck Nice?

  Again, and in the meantime, you got Pluto to hold you over.

• 10:44Speaker 01

  Exactly.

• 10:45Chuck Nice?

  Okay, and that's not so bad.

• 10:46Speaker 01

  It's gonna be a nice show for Pluto, pretty soon.

• 10:48Chuck Nice?

  All right, so, uh, let's go to our next question, also from Facebook, and this is, uh, Tony Anunziata, okay? "When was the first comet discovered?" And what was it called?

• 11:00Speaker 01

  Oh.

• 11:00Chuck Nice?

  Ah, that's a good one.

• 11:02Speaker 01

  Okay, that is a good one.

• 11:03Chuck Nice?

  Little comet history for you there, Amy.

• 11:04Speaker 01

  Cometary history, yes. So actually, I think the first comet was probably observed by ancient humans long before recorded history. And if you look back, you can see drawings of where obviously comets in some very, very ancient texts, you know, from the Chinese, from all over the world, people saw these these strange wandering stars in the sky.

• 11:25Chuck Nice?

  Right.

• 11:26Speaker 01

  And of course, if you were a court astronomer and you did not correctly predict one of these objects' arrivals, you could get in some very big trouble.

• 11:33Chuck Nice?

  Really?

• 11:34Speaker 01

  Oh, yeah. Because comets in a lot of times in the past were considered bad omens.

• 11:40Chuck Nice?

  Okay.

• 11:40Speaker 01

  And frightening. People were scared of them because they didn't know what they were. I mean, they're just these bright things that appear in the sky randomly.

• 11:45Chuck Nice?

  Right. And the gods were angry.

• 11:47Speaker 01

  Yeah.

• 11:48Chuck Nice?

  And of course, we got some really good information from the dinosaurs about, you know.

• 11:52Speaker 01

  Yes, we know today.

• 11:53Chuck Nice?

  What could possibly happen?

• 11:54Speaker 01

  What could possibly go wrong, right?

• 11:56Chuck Nice?

  Right, yeah.

• 11:56Speaker 01

  So nowadays, you know, we have a little better chance at predicting the arrival of comets. And fortunately speaking, as a professional astronomer, I know that it's not off with my head if I don't correctly predict one's arrival.

• 12:07Chuck Nice?

  Right.

• 12:07Speaker 01

  But we still try to do our best.

• 12:08Chuck Nice?

  Yeah. You know, one of my favorite, this is an aside, but now that you said this, one of my favorite animated series of all time is a series called The Avatar. And it's all about, the very beginning of the series is all about the arrival of a comet.

• 12:23Speaker 01

  Oh.

• 12:24Chuck Nice?

  That will give these people superpowers.

• 12:28Speaker 01

  Very cool.

• 12:29Chuck Nice?

  It is cool.

• 12:30Speaker 01

  Well, you know, the kind of funny thing about comets is we think that they may have even brought some of the chemicals we need for life. That's kind of a superpower.

• 12:37Chuck Nice?

  That is a superpower.

• 12:39Speaker 01

  After a way.

• 12:39Chuck Nice?

  So now, let me ask you this. When you, because this is one of the theories that I've heard, is that the Earth, not only is it in a perfect position to support life, but the life itself was seeded on the planet by, in fact, a comet itself.

• 13:00Chuck Nice?

  Is that the case?

• 13:01Speaker 01

  Well, we know for sure that comets have a lot of water and they got a lot of other chemicals in them. They even have, in some cases, I think they know of some really complicated things, which are the precursors of our DNA, basically. So it could be possible, and there are theories out there that say that these comets came in and basically pouted the Earth when it was first formed.

• 13:20Chuck Nice?

  Right.

• 13:21Speaker 01

  And that may have been enough to get the process started.

• 13:24Chuck Nice?

  Nice!

• 13:25Speaker 01

  Pretty cool.

• 13:26Chuck Nice?

  There you go, people. You have your whole life, it's owed to a comet. There you go.

• 13:31Speaker 01

  That's a pretty good omen, right there.

• 13:33Chuck Nice?

  That's not a bad omen. Alright, let's go on with Robert Rushing. And Robert says this, "Greetings from the UK," or should I say, "Greetings from the UK."

• 13:44Chuck Nice?

  "I have heard some theorize that the water on Earth could have been deposited here by comets, which is what you just said. These comets have to come from somewhere. So do you think they orig- so where do you think they originated from? And what is the source of their water?" And that's a really involved question there, and that's a tough one for you to test.

• 14:05Speaker 01

  Well, it's certainly not the tap, clearly.

• 14:09Speaker 01

  They definitely have to come from somewhere far away.

• 14:11Chuck Nice?

  It ain't Avion.

• 14:12Speaker 01

  No, it is not Avion, definitely not. So we know that the comets come from a couple different sources in our solar system. They are, some of them are way out there, and we think they might even be halfway to the nearest star.

• 14:23Chuck Nice?

  Wow.

• 14:24Speaker 01

  Yeah, really far, really cold, super cold, deep freeze. And that stuff that's been out there is very, very old. It is ancient.

• 14:31Chuck Nice?

  Right.

• 14:32Speaker 01

  And it is, again, billions.

• 14:33Chuck Nice?

  Billions.

• 14:34Speaker 01

  Billions.

• 14:34Chuck Nice?

  Billions of years old.

• 14:37Speaker 01

  It's extremely old. So when it gets here, every now and again, we don't even know exactly how, but sometimes these objects get kind of shuffled loose from that cloud that surrounds our solar system. We call it the Oort Cloud. And occasionally, one will get flung inward and bring all of that ice and volatile material inwards. And when it gets to the sun, what happens?

• 14:56Chuck Nice?

  It starts to melt, because our sun's, from what I hear, kind of hot.

• 14:59Speaker 01

  Uh, yes.

• 14:59Chuck Nice?

  Yes.

• 15:00Speaker 01

  Exactly. So the sun basically does a number on the comet, starts to vaporize it, and it can form a big, long tail. And eventually, some of them actually make their way to Earth. We think that that may have been how a lot of the Earth's oceans actually formed.

• 15:14Chuck Nice?

  Wow, are you serious? Like, it was that much ice?

• 15:18Speaker 01

  Could have been, yeah.

• 15:19Chuck Nice?

  So, wow. So, the tail of the comet is actually expelling that much ice that if it were to get caught in the Earth's gravitational pull, pulled down, it creates oceans?

• 15:30Speaker 01

  Imagine lots of comets.

• 15:32Chuck Nice?

  Lots of them.

• 15:33Speaker 01

  Lots of comets. I mean, right now, this is kind of a quiet time in our solar system's history.

• 15:37Chuck Nice?

  Oh, God, you're scaring me.

• 15:38Speaker 01

  And now, we're kind of glad, we're glad for that, right?

• 15:40Chuck Nice?

  Yes, we are.

• 15:41Speaker 01

  Because life here on Earth does not really like it when things get too interesting.

• 15:43Chuck Nice?

  No, exactly.

• 15:44Speaker 01

  So, but early on, when the solar system was first forming, we do think there was a period when the Earth pretty much just got pelted by asteroids and comets. And that could have been when the water got here.

• 15:54Chuck Nice?

  Wow. That is fascinating. Very cool. All right, well, there you go, Robert. That's, uh, there's your answer. That's where this stuff comes from. And, uh, let's hope it never happens again.

• 16:04Speaker 01

  Yes.

• 16:05Chuck Nice?

  Exactly. All right, let's move on to, uh, Dimitri. And, uh, Dimitri wants to know this, writing us from Facebook. What is the biggest asteroid we've ever observed?

• 16:15Speaker 01

  Oh.

• 16:16Chuck Nice?

  If it gets to a certain size and it isn't orbiting anything, is it just considered a rogue planet?

• 16:25Speaker 01

  Oh, ho.

• 16:25Chuck Nice?

  So, compound question. First of all, what's the biggest one we've ever seen and we've recorded? And secondly, what is the size where it's no longer an asteroid that it's just rogue planet? And do we know those answers?

• 16:37Speaker 01

  Right, we do know those answers, although the second answer is kind of a religious warfare question.

• 16:41Chuck Nice?

  Really? Ooh.

• 16:43Speaker 01

  Always the fun stuff.

• 16:44Chuck Nice?

  Yeah.

• 16:45Speaker 01

  But, uh, yeah, the first, the biggest planet, or the biggest asteroid that we know about in our solar system is called Ceres.

• 16:50Chuck Nice?

  Ceres.

• 16:51Speaker 01

  Yes. And it's, I think it's about the size of Texas. It's a big asteroid.

• 16:54Chuck Nice?

  Holy moly.

• 16:55Speaker 01

  But, lucky for us, it is safely away in the main asteroid belt between Mars and Jupiter, so it's not going anywhere.

• 17:02Chuck Nice?

  So, it's not going anywhere?

• 17:03Speaker 01

  No, you don't have to worry about Ceres.

• 17:04Chuck Nice?

  So, Ceres is not trying to make a house call?

• 17:06Speaker 01

  Uh, oh, no. We actually like it right where it is.

• 17:09Chuck Nice?

  Okay.

• 17:09Speaker 01

  We do not want it to come visit us.

• 17:11Chuck Nice?

  Unlike Apophis.

• 17:12Speaker 01

  Which is gonna get really close.

• 17:14Chuck Nice?

  Who's, who's kind of just like peeking in the window.

• 17:16Speaker 01

  Yeah.

• 17:17Chuck Nice?

  Little pervert that it is.

• 17:18Speaker 01

  That is gonna get a little too close for comfort. It won't hit. We are very sure of that.

• 17:22Chuck Nice?

  We're sure of that.

• 17:23Speaker 01

  But we're gonna keep track of that one.

• 17:24Chuck Nice?

  Okay.

• 17:25Speaker 01

  We're gonna keep watching that one.

• 17:26Chuck Nice?

  All right, and so now, uh, the second part of this compound question was, what size, if there is, because I don't know, where it's no longer an asteroid, it's a rogue planet?

• 17:38Speaker 01

  Well, the funny thing about Ceres is it has a joint name. It is also called a dwarf planet. And that's the religious warfare part, right? Because look what happened to poor Pluto. Is it a planet, or is it now what's called a dwarf planet?

• 17:51Chuck Nice?

  Okay, now, before you go any further, is it true that the reason why Pluto isn't really a planet is because it's mostly ice? Is that what it be?

• 17:58Speaker 01

  Oh, boy.

• 17:59Chuck Nice?

  So now, if Ceres were mostly rock, is it really a dwarf planet?

• 18:02Speaker 01

  These are all really tricky questions, and I predict that astronomers are going to be fighting over this for many decades to come.

• 18:08Chuck Nice?

  Oh, so really, this is, this is basically the contention at the Thanksgiving table where it's just full of...

• 18:13Speaker 01

  Yeah, it gets pretty unpleasant at some of these meetings, I gotta say. Astronomers are normally pretty quiet people, but not when it comes to this stuff.

• 18:19Chuck Nice?

  Not when it comes to dwarf planets.

• 18:20Speaker 01

  No. Well, that brings us to the end of this segment, and we'll be right back on StarTalk Radio.

• 18:43Speaker 01

  And we're back on StarTalk Radio. So you ready to go, Chuck?

• 18:47Chuck Nice?

  Yes, I am, Amy, and, uh, we're doing cosmic queries. We've got questions from all over the internet, no matter where they come from, uh, whether it's Facebook, Twitter, or what have you. And this next one is from Marco Horvath. Marco says this, "Everyone knows about Halley's Comet. How often does a comet that is visible to the naked eye appear, and when is the next one?"

• 19:09Speaker 01

  Oh, when is the next super comet?

• 19:12Chuck Nice?

  Yes.

• 19:12Speaker 01

  Oh, boy. Okay, well, there's always a comet of the century that people get really excited about, but they don't happen that often, actually. So, we see naked eye comets, oh, maybe once every few decades or so, something like that. If you're really lucky, one will get really, really active. The thing about comets, though, is they are so hard to predict. They just do whatever they feel like.

• 19:32Chuck Nice?

  Oh, I like that about.

• 19:33Speaker 01

  I know. Sometimes, well, it's annoying if you're an astronomer because you want to know what are you doing, stupid comet, right?

• 19:38Chuck Nice?

  Right.

• 19:39Speaker 01

  So part of the time, we can tell that they're going to get really bright and really active when they get close to the sun, but sometimes they just don't feel like it. And they don't.

• 19:48Chuck Nice?

  They really are like teenagers.

• 19:49Speaker 01

  They are exactly like teenagers, or cats.

• 19:51Chuck Nice?

  Or cats. I like that. Comets, the cats of the universe.

• 19:54Speaker 01

  Exactly.

• 19:55Chuck Nice?

  Come here, come here.

• 19:56Speaker 01

  Yeah, it's like, I don't feel like it.

• 19:57Chuck Nice?

  Oh.

• 19:58Speaker 01

  So we just recently had a so-called comet of the century called Comet Ison.

• 20:03Chuck Nice?

  Comet Ison.

• 20:04Speaker 01

  And it was supposed to make a very close pass by the sun and people thought it might become a spectacular naked eye comet that everybody could see.

• 20:12Chuck Nice?

  Right.

• 20:13Speaker 01

  Thing is, it got a little too close to the sun.

• 20:16Chuck Nice?

  Oh, so now does that negate all of the fireworks because things just burn off so quickly?

• 20:23Speaker 01

  Yeah.

• 20:24Chuck Nice?

  Is that what happens?

• 20:25Speaker 01

  It pretty much was a, it was a bust.

• 20:26Chuck Nice?

  So it's a dud.

• 20:27Speaker 01

  It, it wasn't just even a dud, it was a nothing. I mean, the comet literally fell apart.

• 20:33Chuck Nice?

  Oh, really?

• 20:34Speaker 01

  It got super close to the sun and it got so close that it basically, everybody was watching and waiting to see what would happen and the sun pretty much just.

• 20:41Chuck Nice?

  Just destabilized it completely.

• 20:43Speaker 01

  Yeah, poof, gone.

• 20:44Chuck Nice?

  So now it's just, oh, man, what a shame.

• 20:45Speaker 01

  It was such a disappointment because we were really hoping it would come back and make this great light work, you know, great fireworks show and yeah.

• 20:51Chuck Nice?

  And nothing.

• 20:51Speaker 01

  Nothing, just like.

• 20:53Chuck Nice?

  A big nothing.

• 20:54Speaker 01

  Just like cats.

• 20:54Chuck Nice?

  Uh, kind of like Geraldo Rivera and the vault.

• 20:58Speaker 01

  Yeah, I, oh, I remember that.

• 21:00Chuck Nice?

  Remember that?

• 21:01Speaker 01

  That was really disappointing.

• 21:02Chuck Nice?

  That was very disappointing, right?

• 21:04Speaker 01

  Well, this was the vault of the comet world, Comet Ison.

• 21:07Chuck Nice?

  There we go.

• 21:07Speaker 01

  It was a bust.

• 21:08Chuck Nice?

  All right, Marco, there you have it. That is, uh, that's what's happening. Um, let's move on to Scott McGregor. And here's what Scott wants to know. Do you, Amy, have a favorite asteroid or comet? If so, why? Which one do you think is the most interesting?

• 21:24Speaker 01

  Oh, this is just, this is, no, I can't answer this question. This is like Sophie's Choice.

• 21:29Chuck Nice?

  Is that like asking you to pick a kid?

• 21:30Speaker 01

  I love them all. They're all my favorites. I love them all.

• 21:34Chuck Nice?

  Come on now.

• 21:35Speaker 01

  Okay, well, all right. I like the ones that I discovered.

• 21:41Chuck Nice?

  You really do like your own children.

• 21:43Speaker 01

  I do like my own children. It's kind of bad. Actually, there is one particular weirdo thing that we found with our survey when we were out looking for asteroids. And it's called the first known Earth Trojan. And this is an asteroid that actually is stuck to the Earth in a peculiar way.

• 21:59Chuck Nice?

  Okay, really?

• 22:01Speaker 01

  Yeah.

• 22:02Chuck Nice?

  Now, it's stuck to the Earth?

• 22:05Speaker 01

  It is actually trapped in a gravitational resonance with the Earth, which sounds really cool. And this actually is a really cool asteroid. It's basically, Earth is following it around in its orbit around the Sun.

• 22:18Chuck Nice?

  Sweet.

• 22:19Speaker 01

  And it's kind of trapped there. And what's going to happen is, after a while, eventually it's going to pop its way out.

• 22:25Chuck Nice?

  Right, but right now it's like a little mama's boy.

• 22:27Speaker 01

  Oh, yes.

• 22:28Chuck Nice?

  Just trapped, can't get out.

• 22:29Speaker 01

  Can't get out, won't leave.

• 22:30Chuck Nice?

  Won't leave. And Earth is like, no, you come with me! No, I can't see my baby go.

• 22:37Speaker 01

  She's like, no, no, don't leave me.

• 22:39Chuck Nice?

  So, so that's, that's, okay.

• 22:41Speaker 01

  That's one of my favorites.

• 22:42Chuck Nice?

  That's one of your favorites.

• 22:42Speaker 01

  If I had to pick.

• 22:43Chuck Nice?

  Very cool. All right, let's move on. Nathan Holmes wants to know this, writing in from Facebook. I just read about the Rosetta satellite that would be launching a probe into a comet. Would it be possible to land equipment on the surface? That would, in essence, turn the comet, check this out, into a deep space satellite?

• 23:08Speaker 01

  Ooh.

• 23:08Chuck Nice?

  Yo, that's a brilliant idea.

• 23:10Speaker 01

  That is some cool science fiction right there.

• 23:12Chuck Nice?

  That's some cool sci-fi right there.

• 23:14Speaker 01

  Yeah.

• 23:14Chuck Nice?

  So what is the probability and could it happen?

• 23:16Speaker 01

  Okay, well, so the Rosetta mission is actually going to send a lander to this comet. Now, don't ask me to pronounce the name, I always get it wrong. We call it Cherry Gary for short.

• 23:25Chuck Nice?

  Cherry Gary comet?

• 23:26Speaker 01

  Yeah.

• 23:27Chuck Nice?

  Sounds like a flavor of a soda.

• 23:28Speaker 01

  Yeah, exactly.

• 23:29Chuck Nice?

  I was drinking some Cherry Gary, man, it's delicious.

• 23:31Speaker 01

  It's like Cherryumoff Grasimenco. Yeah, Cherry Gary.

• 23:36Chuck Nice?

  Cherry Gary.

• 23:37Speaker 01

  So this thing is going to land on Cherry Gary, coming up pretty soon. And it's going to basically take a whole bunch of measurements of this comet. It's going to tell us a lot about what it's made out of.

• 23:48Chuck Nice?

  Okay.

• 23:48Speaker 01

  Now, turning an asteroid or a comet into a spaceship, well, that's a tougher thing to do.

• 23:54Chuck Nice?

  Okay.

• 23:54Speaker 01

  That's a lot harder because these things are huge compared to our spacecraft, a lot of them. And this comet is a pretty big one. This is, you know, a kilometer or more across. So it's pretty large and the little lander is really not that much bigger than a suitcase.

• 24:07Chuck Nice?

  Okay.

• 24:08Speaker 01

  It's not a very large lander.

• 24:10Chuck Nice?

  Right.

• 24:10Speaker 01

  So you're really talking about a flea trying to push an elephant.

• 24:13Chuck Nice?

  Okay, I got you. So now, is it possible to hitch a ride on a comet and use it as a deep space probe? Or would that even be necessary?

• 24:26Speaker 01

  Sure. Well, who wouldn't like a ride along with a comet?

• 24:28Chuck Nice?

  Right.

• 24:29Speaker 01

  It could be really fun. So that's kind of what Rosetta is going to do. It's actually going to ride with this comet as it goes around the sun for a while.

• 24:37Chuck Nice?

  Got you.

• 24:37Speaker 01

  And it's going to monitor the comet to see how it changes when it gets too close to the sun, when it, as it heats up, as it cools down. So it is going to teach us a lot about how comets behave.

• 24:46Chuck Nice?

  Sweet.

• 24:48Speaker 01

  Yeah, Rosetta's a pretty cool mission. Really looking forward to it.

• 24:50Chuck Nice?

  Awesome, awesome. Well, there you go, Nathan. There's your answer.

• 24:53Speaker 01

  So we're going to take another short little break here and we will be right back with StarTalk Radio.

• 25:16Speaker 01

  And we're back. We're here on StarTalk Radio Cosmic Queries Edition. And check us out on social media. We are all over the internet. We're at StarTalkRadio.net and you can catch us on Facebook and Twitter at StarTalk Radio.

• 25:28Chuck Nice?

  Absolutely. Well, let's jump right back into this, Amy. We have from Yelena Noskina, who actually has kind of a follow-up question. Some comets are said to be traveling for thousands of years and yet we see Ison get burned up by the sun. How is it that we have comets at all?

• 25:52Speaker 01

  So Ison was a spectacular science event of the year. This is a comet that came in from the Oort Cloud. It came in from far away and it has been out there for billions of years.

• 26:03Chuck Nice?

  Right, right.

• 26:04Speaker 01

  Wait, you have to say it.

• 26:05Chuck Nice?

  Billions of years.

• 26:07Speaker 01

  Yeah, that.

• 26:08Chuck Nice?

  Right.

• 26:09Speaker 01

  So it came in and it made its way into the inner solar system. But not only did it get in, but it made a very close brush with the sun. Just a few times the radius of the sun itself. And that is so hot. The thing is, is people had no idea what was going to happen. Now, we see sun, what we call sun grazer comets. And these are little tiny comets by and large that just get pulled into the sun. We see them with our satellites that are actually watching the sun. And the sun just eats them up, just like breakfast cereal.

• 26:37Chuck Nice?

  There you go. It's a Scooby snack for the sun.

• 26:40Speaker 01

  Exactly.

• 26:40Chuck Nice?

  Comets.

• 26:41Speaker 01

  Exactly. Well, this one was a much bigger comet.

• 26:45Chuck Nice?

  Okay.

• 26:46Speaker 01

  This was about more than a kilometer across. It's mostly very primitive ice that sat there from the beginning of time.

• 26:53Chuck Nice?

  Wow.

• 26:53Speaker 01

  Okay, the beginning of our solar system, anyway.

• 26:55Chuck Nice?

  Right.

• 26:55Speaker 01

  And when it got close to the sun, nobody knew. Was it gonna flare up and put on this spectacular light show in our night sky? Or was the sun just gonna tear it apart? And we were watching this thing on our satellites in real time. It was really spectacular. I mean, these satellites allow us to have this great view of the thing.

• 27:13Chuck Nice?

  Right.

• 27:13Speaker 01

  Well, turns out the sun tore it apart.

• 27:16Chuck Nice?

  Tore it apart.

• 27:17Speaker 01

  Yeah.

• 27:17Chuck Nice?

  Dag. So it just, basically, the sun is Thunderdome for comets.

• 27:23Speaker 01

  Poor old comet Ison did not leave the Thunderdome.

• 27:26Chuck Nice?

  Did not leave the...

• 27:28Chuck Nice?

  One comet checks in, no comet checks out.

• 27:32Speaker 01

  Yeah, it was pretty disappointing for comet watchers.

• 27:35Chuck Nice?

  So, uh, basically, it's kind of like, um, you know, it's very fortuitous to be able to see a comet, you know, get into our solar system, get by the sun, and then continue on so that we can see this spectacular display in the sky.

• 27:53Speaker 01

  Absolutely, yeah.

• 27:54Chuck Nice?

  Because what you're saying is these sun grazer comets, as you called them,

• 27:57Speaker 01

  Yep.

• 27:57Chuck Nice?

  happen all the time.

• 27:58Speaker 01

  Yeah, they happen all the time. And that was a huge surprise until we really started monitoring the sun consistently.

• 28:03Chuck Nice?

  Right.

• 28:03Speaker 01

  We didn't know about these things. I mean, we saw comets that, you know, kind of went around the sun and didn't get too close and they went on their merry way. But these sun grazers, they just get swallowed up whole.

• 28:14Chuck Nice?

  Well, there you go, Yelena. There's your answer. The sun, the roach motel for comets.

• 28:20Chuck Nice?

  All right, let's move on. We have Anton Prius. And Anton says, could we ever send some sort of organism to test if they could survive on an asteroid or a comet? So now, we're always interested in pulling stuff off of these things.

• 28:39Speaker 01

  Sure.

• 28:39Chuck Nice?

  Could we put something on it?

• 28:41Speaker 01

  Ooh, well, this is a toughie. Okay, so in a sense, we kind of already have. When we send spacecraft to asteroids, there was a spacecraft called NEAR, the Near Earth Asteroid Rendezvous Mission, and it went, and it actually touched down on an asteroid. In a curious sense, we do our very best to clean these spacecraft and get them super duper clean. But you know, there's always little bits of germs and bacteria that are left. We try really hard to get them super clean. So I'm sure there's a little bit of some space DNA now out there on that asteroid. Whether it survived, of course, probably not. Asteroids are pretty hostile. There's no air.

• 29:16Chuck Nice?

  Right.

• 29:16Speaker 01

  For most of these things.

• 29:17Chuck Nice?

  Right.

• 29:18Speaker 01

  And they can get either burningly hot or terribly, terribly cold.

• 29:22Chuck Nice?

  So it's very unlikely that life would be able to survive on an asteroid.

• 29:28Speaker 01

  That would be my guess. You know, it's a, it's a nice place here on Earth, and it's probably not such a nice place to take a vacation.

• 29:35Chuck Nice?

  There you go. So, but we can always hope.

• 29:38Speaker 01

  Yeah, there is always hope.

• 29:40Chuck Nice?

  Unfortunately, whatever did survive there would probably come back and kill us all. Like Wrath of Khan.

• 29:46Speaker 01

  Yeah, that's it. Andromeda strain style, that's it.

• 29:49Chuck Nice?

  Exactly, Andromeda strain, exactly. All right, let's move on. We got Jake Betcher, at Jake Betcher. He says, if an asteroid were on a collision course for Earth, what method would be used to deflect it, and how long would it take to prepare this?

• 30:03Speaker 01

  You got it. Okay, so we actually think about this a lot. And what we try to do is find the asteroids well in advance of any potential close encounters, because that gives us the most flexibility to design a mitigation system. There are options to deflect it by just, you know, simply whacking into it.

• 30:19Chuck Nice?

  Just hit it.

• 30:19Speaker 01

  Just hit it. The Deep Impact Mission actually did that with a comet in 2005. It just ran into the comet.

• 30:24Chuck Nice?

  Right.

• 30:25Speaker 01

  And that actually can push something. If you have enough time. You might be able to do something that's just a simple kinetic impactor.

• 30:31Chuck Nice?

  So there you go, Jake. Your answer is just like your health, early detection is the key.

• 30:36Speaker 01

  Exactly. So we're going to have more here when we come back to StarTalk Radio.

• 30:59Speaker 01

  And we're back on StarTalk Radio. I'm Amy Mainzer, your friendly neighborhood astrophysicist from the Jet Propulsion Laboratory, and I'm here with Chuck Nice. And now it's time for the lightning round.

• 31:09Chuck Nice?

  Yes.

• 31:10Speaker 01

  Okay.

• 31:11Chuck Nice?

  And that's the sound you will hear when you finish answering the question, or when Amy finishes answering the question. And let's jump right into this.

• 31:19Speaker 01

  Here we go.

• 31:20Chuck Nice?

  Steve B. from Twitter wants to know, who tweets at @BeerCannon, "Is there a maximum speed for asteroids/Comets and could something approach so quickly that we'd never see it coming?"

• 31:30Speaker 01

  Oh, the average speed of most asteroids and comets is about 20 or 30 kilometers per second. That's really fast.

• 31:36Chuck Nice?

  That's very fast.

• 31:37Speaker 01

  Forty thousand miles an hour. And it is possible that they sometimes come in faster depending on their orbits. Things can come in from directions that we cannot see.

• 31:47Chuck Nice?

  Oh, that is not the answer I wanted to hear.

• 31:49Speaker 01

  Oh.

• 31:50Chuck Nice?

  Okay. Shahan Tasneem wants to know this. "How plausible is the theory that our moon was the result of an asteroid strike on Earth? If true, are there any other planets that have moons resulting from the same event?"

• 32:03Speaker 01

  Aha. Okay, well, we think one theory is that a Mars-sized protoplanet hit the Earth when the Earth was forming. It actually scraped off the crust of the protoearth and formed our moon. It is potentially possible that this could have happened on other worlds.

• 32:17Chuck Nice?

  Okay, good to know. Anna Williamson wants to know this. "How big of an asteroid would it take for a strike to break the Earth?" Would it have to be a moon-sized asteroid?

• 32:33Speaker 01

  She wants to know, like Alderaan-style destruction?

• 32:36Chuck Nice?

  That's it, just obliterate.

• 32:39Speaker 01

  All right, well, we think that a Mars-sized protoplanet was enough to knock off the moon, but not destroy the Earth. So for something like that to happen, it would have to be a pretty big object, almost the size of the Earth.

• 32:50Chuck Nice?

  Ah, one-to-one ratio.

• 32:51Speaker 01

  Yeah.

• 32:52Chuck Nice?

  Okay, so Phil Green would like to know this. In the movie Armageddon, they were describing how a rogue comet went through the asteroid field and all that rock turned Earth into a shooting gallery. Is that scenario realistically possible?

• 33:08Speaker 01

  Well, the Armageddon movie had a few flaws, surprise, surprise.

• 33:12Chuck Nice?

  Shock, shock, shock.

• 33:14Speaker 01

  Shocking, but the thing they got mostly right is that if a very large comet were to come in, it would certainly cause a lot of destruction. We do think that the asteroid belt was reshuffled early on in the formation of our solar system in an event called the late heavy bombardment.

• 33:29Chuck Nice?

  Uh-huh. Boom, there's your answer. Late heavy bombardment, deal with that, Phil. All right, here's one from Rich Coto. Can an asteroid consisting of gold or silver be out there? And if it hit the Earth, who would own it?

• 33:46Speaker 01

  Well, I say I would love to find a gold or silver asteroid if I could, but the ones we find that are metallic tend to be nickel-iron.

• 33:54Chuck Nice?

  Nickel-iron, not nearly worth as much.

• 33:57Speaker 01

  No, not nearly as much fun.

• 33:58Chuck Nice?

  And the answer to the second part of the question is, if it does exist, I own it, okay Richie? Okay, so just back up off my asteroid. Get off my ass, Troy. Okay. This is from Twitter, I H Y H, okay? Is there a possibility of discovering new elements that are not on our periodic chart? Can we find that in asteroids?

• 34:23Speaker 01

  Oh, well, we certainly find a lot of very exotic materials that are not common here on Earth because they have sunk to the center of our planet long ago. Maybe it's remotely possible that someday somebody will find one that is way out there on the periodic table. Hasn't happened yet, mostly these very exotic weirdo elements are created in laboratories.

• 34:42Chuck Nice?

  Ah, so we don't even need asteroids for that. There's your answer. So Melanie Bowman wants to know this. Would it be possible to redirect a comet to hit Mars for terraforming purposes? After impact, would terraforming work? Or would it just make a Martian mess?

• 35:01Speaker 01

  Oh, well, we do actually have a comet that is getting very close to Mars. It will not impact, so we don't get to do the experiment. Now, comets are pretty big, really big. A lot of them are more than a kilometer across, and that is very hard for us to move. Unfortunately, it's not easy for us to do that experiment, so we don't know.

• 35:21Chuck Nice?

  Oh, my goodness. We got a we don't know. Look at that, Melanie. Okay, um, this one comes from Google Plus, and Elad Avran wants to know this. Can comets travel between star system? Or are they always bound to one star?

• 35:39Speaker 01

  Oh, this is a toughie. Okay, so we think that the comets in our Oort Cloud, which is a shell that kind of surrounds our solar system, and we are a tiny, tiny thing in the middle. Well, we think that sometimes it's possible for a nearby passing star over the course of many

• 35:54Chuck Nice?

  billions of years

• 35:56Speaker 01

  could potentially grab some of our Oort Cloud comets and pull them off. It could happen.

• 36:01Chuck Nice?

  So the answer is yes.

• 36:03Speaker 01

  Yes.

• 36:05Chuck Nice?

  Cool. Okay, Alex Fawcett wants to know this. How scientifically accurate is the 1979 Atari game Asteroids?

• 36:14Speaker 01

  Okay, I spent way too much of my childhood playing that game.

• 36:17Chuck Nice?

  Me and you both.

• 36:18Speaker 01

  Yes, and so when I became an asteroid scientist, it turns out the game is actually not that bad. If you hit an asteroid that is big in the game, it breaks into a lot of little pieces. And sure enough, that is exactly what happens to the asteroids.

• 36:31Chuck Nice?

  Wow. That is awesome. All right, here's a very quick one. What role do you think plasma physics plays in the landscape of comets?

• 36:40Speaker 01

  Oh, my goodness, a confusing one.

• 36:44Speaker 01

  Okay. And that's all the time we've got for this lightning round on StarTalk Radio. Thank you so much Chuck Nice for being a great co-host.

• 36:51Chuck Nice?

  Thank you. It was seriously a pleasure.

• 36:53Speaker 01

  It's been a blast. And I'm Amy Mainzer. I'm an astrophysicist at NASA's Jet Propulsion Laboratory. I'm co-hosting the show for our own Neil deGrasse Tyson, who is off around the cosmos right now. So, check us out on StarTalkRadio.net and we're on StarTalk Radio on Twitter and on Facebook. Thanks so much and clear skies, everyone.