Cosmic Queries: Planet Earth

StarTalk Radio comes down to Earth as astrophysicist Neil deGrasse Tyson and comic co-host Chuck Nice answer fan questions about our home planet, from how it formed to how it might end.

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.

• 0:21Neil deGrasse Tyson?

  This is StarTalk. I'm your host Neil deGrasse Tyson. I'm an astrophysicist with the American Museum of Natural History, right here in New York City. In studio is the one, the only Chuck Nice.

• 0:34Chuck Nice?

  Hey Neil, what's happening?

• 0:35Neil deGrasse Tyson?

  Chuck, good to have you. This is the Cosmic Queries edition of StarTalk.

• 0:39Chuck Nice?

  Yes it is.

• 0:40Neil deGrasse Tyson?

  I like to think of it as StarTalk after hours. But it's not after hours, it's like broad daylight outside right now. So, sometimes we do them random, you know, popery, but today it's themed to the Earth. I haven't seen any of these questions.

• 0:55Chuck Nice?

  That is correct.

• 0:55Neil deGrasse Tyson?

  Questions that come in from our fanbase and our listeners, from all our social networks.

• 1:00Chuck Nice?

  That is correct.

• 1:01Neil deGrasse Tyson?

  Why do we make a category, I'm like an astrophysicist, I care about everything that's not Earth.

• 1:05Chuck Nice?

  Right, you're not a terrestrial physicist.

• 1:07Neil deGrasse Tyson?

  I'm not a terrestrial, thank you!

• 1:08Chuck Nice?

  He's an astrophysicist.

• 1:09Neil deGrasse Tyson?

  Thank you, so we'll see how far I get. I know some osmotic things that the geophysicists tell me, but otherwise we'll see how. I can answer questions about Earth as a planet.

• 1:20Chuck Nice?

  Okay.

• 1:20Neil deGrasse Tyson?

  Alright.

• 1:21Chuck Nice?

  Well, you know what, we'll see.

• 1:22Neil deGrasse Tyson?

  We'll find out.

• 1:22Chuck Nice?

  We'll see, we'll find out.

• 1:23Neil deGrasse Tyson?

  At first I've ever heard these.

• 1:24Chuck Nice?

  Yep, the first time you've ever heard them, that's my favorite part. So let's jump right into it. And we've got Ryan Mizak. Ryan Mizak.

• 1:31Neil deGrasse Tyson?

  From?

• 1:32Chuck Nice?

  Well, the question's from Facebook, but Ryan does not notate where he is from. How was the Earth formed? What happened at the birth of the planet? Well, and that, that, that goes for not just this planet, pretty much planets.

• 1:48Neil deGrasse Tyson?

  Yeah, exactly. Well, we can split planets into two varieties, rocky planets, of which we are, and gaseous planets. Jupiter, Saturn, Uranus, and Neptune are, are gassy.

• 1:59Neil deGrasse Tyson?

  You mean Uranus is gassy? I had to do it. I had to. Somebody's gotta go there. I'm ashamed of myself right now. Somebody in every show's gotta go there. Gotta go there. Go ahead. All right. So what we think happened here is as the, the original nebula that formed the solar system, it would form the sun first, that's where the strongest gravity is, the greatest accelerations of particles into it. You can make the sun. Now, that's where the interesting things happen because now the sun begins to heat the remaining rest of the gas that's trying to condense and make other kinds of objects. So, in our solar system, we may have had a huge gaseous envelope, but we don't anymore. We don't have enough gravity to hold on to it. Gotcha. All right.

• 2:43Neil deGrasse Tyson?

  You, um, for example, if you have a helium balloon and you let the gas out, helium travels very fast in our air. Mm-hmm. So fast that it, if it gets to the top of the atmosphere, it will escape forever. Wow. We don't have enough gravity to hold on to our helium. But Jupiter and Saturn do. So Jupiter and Saturn are, you know, they're almost 10% helium in each one of those. So, if you don't have enough gravity to begin with, you'll hold your rocks, you don't hold your gas. Gotcha. That's what I'm saying.

• 3:14Neil deGrasse Tyson?

  So, now, there's a point where Earth would have been sort of molten, because things are very hot in the early solar system. When you're molten, heavy things can fall to the middle and light things rise to the top. So guess what, what kind of core we have? So we have a very heavy metal core. Heavy metal, iron core. Iron core. Yeah, nearly all the iron in Earth settled to the core. And the light stuff, like this, what we call, what the geologists call the silicates. So, there's a lot of silicon and, uh, bound with oxygen. Silicon and oxygen, that's like the active ingredient in rock, basically, all right? So, um, these are the light elements compared with iron and nickel and cobalt and, and all the rest of that. So, Earth has been what we call differentiated in its density. And, and there you have it.

• 3:59Neil deGrasse Tyson?

  And then it cools in place. It cools in place. So then you have different layers and different as you go down. Now, you know the rarest meteorite? It's called a palisite. meteorite is the broken remains of a planet that was differentiating its material. The light things floating to the top, the heavy things sinking to the bottom, but it froze before everything fully separated. And you capture the light things rising up through it and the heavy things coming down. It is the it is the combination of these two ingredients in one mass.

• 4:32Chuck Nice?

  So it's those two things kind of passing in the night.

• 4:35Neil deGrasse Tyson?

  Passing in the night.

• 4:36Chuck Nice?

  And then there's a snapshot of that found in that rock or that meteorite.

• 4:41Neil deGrasse Tyson?

  Chuck, I could not have said it better.

• 4:42Chuck Nice?

  Yes, you could have.

• 4:43Neil deGrasse Tyson?

  No, I could not have said it as simply and beautifully. You you came through on that one.

• 4:48Chuck Nice?

  Well, I got a simple, beautiful mind.

• 4:50Neil deGrasse Tyson?

  So there you have the earth and we kept our heavier gases in the atmosphere.

• 4:52Chuck Nice?

  It's fantastic, man. That was really good.

• 4:55Neil deGrasse Tyson?

  Okay, what else you got?

• 4:56Chuck Nice?

  Okay, let's move on to Omar Buckingham. That's the name.

• 5:00Neil deGrasse Tyson?

  The third, yes. Where's the Roman numeral?

• 5:02Chuck Nice?

  Indeed, Omar Buckingham the third.

• 5:06Chuck Nice?

  Could a shift in the magnetic poles happen in the near future? Uh, how does that occur and what would that mean for both humans biologically as well as technologically?

• 5:18Neil deGrasse Tyson?

  Okay, dude, we the poles are shifting all the time.

• 5:22Chuck Nice?

  Okay.

• 5:22Neil deGrasse Tyson?

  All the time, all right? And we say, oh, compass points north. No, it points to the north magnetic pole, which is not near the north geographic pole, like where Santa is like North Pole.

• 5:34Chuck Nice?

  Right.

• 5:34Neil deGrasse Tyson?

  Bar none, all right? The magnetic pole is like in Canada somewhere, all right? So people who in the old days, pre GPS, who hiked with compasses would need a magnetic, what they called it, uh, was it a declination or decrement? They need to know what angle difference between the compass and true north would give you depending on where they were in the world.

• 5:55Chuck Nice?

  Is that where true north comes from?

• 5:56Neil deGrasse Tyson?

  True north is is the north is Santa.

• 5:59Chuck Nice?

  Right.

• 6:00Neil deGrasse Tyson?

  And true north is the difference between true north and magnetic north, that difference you have to keep track of.

• 6:05Chuck Nice?

  Gotcha.

• 6:05Neil deGrasse Tyson?

  Otherwise, you're you're lost, all right? So a compass is only good as how close the north pole is to the north pole, all right?

• 6:11Chuck Nice?

  Gotcha.

• 6:12Neil deGrasse Tyson?

  Now, here's something cool. You ready? Do you realize? That the north pole of a compass points to the north pole of the earth. But you've played with magnets before. What happens when you bring two north poles together?

• 6:26Chuck Nice?

  Well, they kind of hate each other.

• 6:27Neil deGrasse Tyson?

  They repel.

• 6:28Chuck Nice?

  That's right.

• 6:29Neil deGrasse Tyson?

  Yet your north pole on a magnet is pointing to the north pole of the earth. That tells you that earth's north pole actually has the south magnetic center.

• 6:38Chuck Nice?

  Oh.

• 6:41Chuck Nice?

  So it's just the opposite.

• 6:42Neil deGrasse Tyson?

  It's just the opposite.

• 6:43Chuck Nice?

  It's just the opposite.

• 6:45Neil deGrasse Tyson?

  The north magnetic pole of the earth is earth's south pole.

• 6:48Chuck Nice?

  Oh, man.

• 6:48Neil deGrasse Tyson?

  That's why all north poles of magnets point there.

• 6:51Chuck Nice?

  Oh, my. That is amazing.

• 6:53Neil deGrasse Tyson?

  You didn't know that?

• 6:54Chuck Nice?

  No, no, because you think it's north pole. That's what you've been told.

• 6:57Neil deGrasse Tyson?

  That's what you point to if you're north.

• 6:59Chuck Nice?

  But you're right. But but the north pole of the magnet would not point towards the north pole.

• 7:03Neil deGrasse Tyson?

  It would go the opposite.

• 7:04Chuck Nice?

  It would go the opposite way. So the north pole is actually the south pole.

• 7:07Neil deGrasse Tyson?

  Exactly. I'm just saying.

• 7:09Chuck Nice?

  So Saturn is truly at the south pole.

• 7:12Neil deGrasse Tyson?

  Yes, south, uh, near the south magnetic pole.

• 7:14Chuck Nice?

  The south magnetic.

• 7:15Neil deGrasse Tyson?

  The real rotational north pole.

• 7:16Chuck Nice?

  That's the real one, right.

• 7:17Neil deGrasse Tyson?

  Exactly. So, uh, the poles not only wander, they've actually diminished in intensity and increased over time. Right now, we're on a diminishing intensity pole. The worry is if it goes away, then what happens to the like solar particles and radiation that hits the earth? Do we all go extinct?

• 7:34Chuck Nice?

  Yes.

• 7:35Neil deGrasse Tyson?

  We're worried about that. So you look at the record of where the pole has been. We have that because it freezes, quote, freezes into the lava that comes out of volcanoes. It remembers what orientation the pole was at the time it solidified. So you have a whole tracking of the history of where the magnetic pole was. And after this break, you'll find out whether we go extinct or not. You're listening to StarTalk Radio. Back in a moment.

• 8:18Neil deGrasse Tyson?

  We're back on StarTalk Radio Cosmic Queries Edition. I'm Neil deGrasse Tyson. Chuck Nice.

• 8:25Chuck Nice?

  Yes Neil.

• 8:25Neil deGrasse Tyson?

  Is with me.

• 8:26Chuck Nice?

  Yes I am.

• 8:26Neil deGrasse Tyson?

  You're one of our regulars Chuck.

• 8:28Chuck Nice?

  I'm glad to be a regular.

• 8:29Neil deGrasse Tyson?

  I just heard you had a kid. Why didn't you tell me this?

• 8:31Chuck Nice?

  Oh man, you didn't know?

• 8:32Neil deGrasse Tyson?

  How old's your baby?

• 8:33Chuck Nice?

  Um, well, right now, four weeks.

• 8:36Neil deGrasse Tyson?

  Four weeks?

• 8:36Chuck Nice?

  Four weeks.

• 8:37Neil deGrasse Tyson?

  Okay, we call that a month. Alright, just so you know. Well, congratulations, it's your third.

• 8:41Chuck Nice?

  Hey, thank you, it's my third. It's a little girl.

• 8:42Neil deGrasse Tyson?

  Baby-making machine, you.

• 8:44Chuck Nice?

  Oh god, you're telling me.

• 8:45Neil deGrasse Tyson?

  Congratulations. What's her name?

• 8:47Chuck Nice?

  Uh, Charlie London.

• 8:48Neil deGrasse Tyson?

  Charlie London.

• 8:49Chuck Nice?

  Charlie London is her name.

• 8:50Neil deGrasse Tyson?

  A shout out to Charlie London. Welcome to the universe.

• 8:53Chuck Nice?

  Thanks.

• 8:53Neil deGrasse Tyson?

  Yeah, cool. Uh, so, Cosmic Queries Edition, we're talking about Earth. And I claim expertise on Earth as a planet, globally, not like Earth as a geologist.

• 9:03Chuck Nice?

  Right.

• 9:03Neil deGrasse Tyson?

  Don't ask me what the molecular form of orthoclase feldspar is. I won't know. Okay? Alright. So, I haven't seen these questions before, so what do you have? What's next?

• 9:13Chuck Nice?

  Okay, let's move on. And, uh, this, uh, next question comes from David Worley.

• 9:19Neil deGrasse Tyson?

  Mm-hmm.

• 9:19Chuck Nice?

  This is just a personal question for you. So this isn't really like a science thing. He's just wants, he's picking your brain.

• 9:25Neil deGrasse Tyson?

  Okay.

• 9:26Chuck Nice?

  Okay?

• 9:26Neil deGrasse Tyson?

  Even though we are on the air and this is a science show.

• 9:29Chuck Nice?

  This is true.

• 9:30Neil deGrasse Tyson?

  Okay, go.

• 9:30Chuck Nice?

  But you know, you gotta sometimes indulge.

• 9:33Neil deGrasse Tyson?

  I'll roll with it.

• 9:33Chuck Nice?

  You gotta indulge. Taking into account the natural earthbound disasters such as earthquakes, flooding, drought, tsunami, and last, but certainly not least, volcanoes. Neil, where's the safest place you'd like to live?

• 9:52Neil deGrasse Tyson?

  The safest place?

• 9:53Chuck Nice?

  The safest place you'd like to live?

• 9:55Neil deGrasse Tyson?

  Actually, the safest place is like the International Space Station, where you could watch it from above.

• 9:59Chuck Nice?

  There you go.

• 10:00Neil deGrasse Tyson?

  No, there are some places that are not as susceptible, uh, to natural disaster. The United States, you know, there's all this "God bless America" stuff, but we like lead the world in tornadoes and, and we get these mondo hurricanes and we, you know, we are like, you know...

• 10:16Chuck Nice?

  We're disaster central.

• 10:17Neil deGrasse Tyson?

  Disaster central.

• 10:18Chuck Nice?

  Not only in real life, but in the movies as well.

• 10:20Neil deGrasse Tyson?

  We got everything but the frogs and the locusts, you know?

• 10:22Chuck Nice?

  Yeah.

• 10:22Neil deGrasse Tyson?

  Uh, basically, we have the, the, the fires, the floods, that we've got all of that. So what you want to be is a place that is not as susceptible to the fluctuations in climate. And among those places would be like rainforests, for example.

• 10:36Chuck Nice?

  Ah.

• 10:36Neil deGrasse Tyson?

  Right, the climate, by the way, uh, Seattle is at a latitude that promotes rainforests. So, uh, Seattle, I don't know that they have tornadoes, floods, you know.

• 10:46Chuck Nice?

  No.

• 10:46Neil deGrasse Tyson?

  It's pretty stable.

• 10:47Chuck Nice?

  Just dreary rain.

• 10:49Neil deGrasse Tyson?

  The sun never comes out.

• 10:51Chuck Nice?

  Just dreary rain all the time.

• 10:53Neil deGrasse Tyson?

  If you're okay with no sun.

• 10:54Chuck Nice?

  Yeah.

• 10:55Neil deGrasse Tyson?

  You're cool. Um, and the Brazilian rainforest, that's why it is so rich in its bio, in its, uh, it, it's one of the richest parts of the biosphere.

• 11:03Chuck Nice?

  Right.

• 11:04Neil deGrasse Tyson?

  Life can thrive there. Life has a hard time if you stress it with climate, you know, fire, flood, whatever.

• 11:12Chuck Nice?

  I believe me, I know.

• 11:13Neil deGrasse Tyson?

  So the rainforest latitudes are, are, are great places. Now, you'd be, uh, infected with bugs and other kind, you know.

• 11:19Chuck Nice?

  Right.

• 11:19Neil deGrasse Tyson?

  Malaria and everything. You'd be dead for other reasons.

• 11:21Chuck Nice?

  Not to.

• 11:22Neil deGrasse Tyson?

  But not, not because Earth as a planet killed you.

• 11:25Chuck Nice?

  Not to mention all the loggers you'd have to fight off.

• 11:27Neil deGrasse Tyson?

  Not nowadays.

• 11:28Chuck Nice?

  For your rich natural resources.

• 11:29Neil deGrasse Tyson?

  Correct.

• 11:29Chuck Nice?

  Yeah. All right, let's move on to the phone, and I believe on the line.

• 11:33Neil deGrasse Tyson?

  You got a caller.

• 11:34Chuck Nice?

  Got a caller.

• 11:34Neil deGrasse Tyson?

  Nice.

• 11:35Chuck Nice?

  And this is Magic from LA, Neil. Magic from LA.

• 11:39Neil deGrasse Tyson?

  Of course. Okay. Uh, so what is Magic, what is Magic?

• 11:42Chuck Nice?

  Magic, are you there?

• 11:43Speaker 02

  Yeah, I'm here.

• 11:44Neil deGrasse Tyson?

  Uh, uh, that's not Magic Jones.

• 11:45Speaker 02

  No, it's not Magic Jones. No, no.

• 11:49Neil deGrasse Tyson?

  Okay, Magic, uh, what do you have for us?

• 11:52Speaker 02

  Well, I wanted to know if you put all of the natural resources together on Earth, how much would our planet be worth?

• 12:01Chuck Nice?

  Oh.

• 12:02Neil deGrasse Tyson?

  Wow. Oh, he's trying to trade Earth on the open market.

• 12:04Chuck Nice?

  What are you, a Ferengi?

• 12:06Speaker 02

  I'm, I'm a, I'm a registered stockbroker, so, uh, you know, I always ask these questions.

• 12:11Neil deGrasse Tyson?

  What is Earth worth? Oh, ouch.

• 12:14Chuck Nice?

  What is Earth worth?

• 12:15Neil deGrasse Tyson?

  Ouch.

• 12:16Chuck Nice?

  Who would ever think of that?

• 12:17Neil deGrasse Tyson?

  Ooh.

• 12:17Chuck Nice?

  Well, I do know this much.

• 12:18Neil deGrasse Tyson?

  What's that?

• 12:19Chuck Nice?

  I know we have, uh, uh, sixty trillion dollars worth of oil in the ground, which is why we can't get any legislation passed to stop killing the Earth.

• 12:29Neil deGrasse Tyson?

  Right, because it's cheaper to pull energy out of the ground. Right, so, okay, I don't have that number, but let me, I can address certain aspects of it. There's the oil, there's the coal, there's the minerals, which includes diamond and, you know, and then there are the, the, the elements from the periodic table that have value to our industry. There's copper, there's cobalt, there's iridium, there's, um, so you just go right on down, there's uranium. Helium is becoming expensive, okay? Yeah, here we're running out of it. Now, helium is like one of the most pop, one of the most common ingredients in the universe, but on, as we said in an earlier segment, helium, if it's in our atmosphere, migrates to the top of the atmosphere and escapes into space. Right.

• 13:13Neil deGrasse Tyson?

  In the old days, the Macy's Thanksgiving Day Parade, they would, with the helium balloons, they would release the helium back into the air and refill it every year. They don't do that anymore. No, they keep it now. They re, they re-canister that. Uh, Macy's Day Parade, the second largest consumer of helium in the world, after the US government. And children at parties who wanna talk funny. That's, talk like Mickey Mouse. So, if you add it all up, I, I don't know how, I wouldn't know how to say that, but it's maybe quadrillion, I mean, if there's a number, a quadrillion is a thousand times bigger than a trillion. Uh, maybe, if I had to pick a number, I'd say a quadrillion dollars. So what is Earth worth to somebody else who wanted rental? But here's the problem, some of the value of those minerals is because they're rare. Hmm.

• 13:56Neil deGrasse Tyson?

  If you haul in an asteroid that is rich in gold, platinum, iridium, then the price that you are now trading it at on Earth. Will plummet. Will plummet, and then it's a whole other valuation. Right. So, if you're worried about aliens taking our resources, and you wanna like, charge them for it in a, in a, in a swap of currency, I, I don't know that that's gonna matter, cuz on the route here from their home planet, they're gonna pass asteroids. That they'll be able to mine for all the things that we find rare. In fact, they won't have to mine, just haul the, haul it in. Just haul the damn thing in. Right. Take a bite out of it, it was sitting there on the ground, right? No drilling, no shipping, just there it is.

• 14:38Neil deGrasse Tyson?

  So, the value of resources is, as you know, if you're a stockbroker or into economics at all, is a function of not only the demand, but the supply, and the cost of acquiring it, uh, wherever it happens to be. So, it's a quadrillion dollars to us. Right. But to aliens, uh. We're worthless. Food stamps. Food stamps. It's food stamps.

• 15:02Neil deGrasse Tyson?

  So, thanks, Magic. Thank you so much, Doctor. All right, thanks for checking in.

• 15:06Chuck Nice?

  Okay, that was a lot of fun.

• 15:07Neil deGrasse Tyson?

  Chuck, what else you got?

• 15:08Chuck Nice?

  Okay, this, this is a little geol- geol- geol- geologist oriented.

• 15:12Neil deGrasse Tyson?

  Then I'll get to say I have no clue.

• 15:13Chuck Nice?

  Okay, go on. But let me go, what is the furthest limit of the fossil and tectonic record? And what is known about how much further back the Earth supported a stable crust and life? I have heard-

• 15:26Neil deGrasse Tyson?

  Okay, Earth has never had a stable crust. Just look around.

• 15:29Chuck Nice?

  Whoa.

• 15:30Neil deGrasse Tyson?

  No, it's churning daily. That's why we have earthquakes.

• 15:32Chuck Nice?

  Right.

• 15:33Neil deGrasse Tyson?

  Go look, look at the USGS earthquake page on the internet. And it's a record of all the earthquakes in the world? There are like hundreds a day.

• 15:41Chuck Nice?

  Every day.

• 15:42Neil deGrasse Tyson?

  Every day.

• 15:43Chuck Nice?

  Every day there's earthquake.

• 15:43Neil deGrasse Tyson?

  The only ones you hear about are the ones that shake and bake a city.

• 15:46Chuck Nice?

  Right.

• 15:46Neil deGrasse Tyson?

  But there are, there are tremors, there are, you know, uh, level two, three, four, and five. Uh, New York City had one last year, for goodness sake. Okay, not a big enough to topple buildings, but, and that was based in Virginia, I think it was, and it was very-

• 16:00Chuck Nice?

  It was, that's right.

• 16:01Neil deGrasse Tyson?

  The energy was spread out, so it thinned out the energy. Um, so that's why, you know, there was no real disasters from that, from that earthquake. So, we, we've never had a stable crust. A, it's still not stable and it'll remain unstable for a long time to come. B, C, the earliest fossil evidence of life goes back, if you push it, if you really push it, 3.7, 3.8 billion years.

• 16:27Chuck Nice?

  3.8 billion?

• 16:28Neil deGrasse Tyson?

  Yeah, these are single-celled organisms. That's correct. And before, here's what happens, if you wait long enough, the landmass that you're on subducts beneath other landmasses-

• 16:39Chuck Nice?

  Right.

• 16:39Neil deGrasse Tyson?

  And rejoins the mantle and comes back out as a volcano, as lava. So, Earth remakes its surface over several billion years. So, that's why the oldest rocks on Earth are not as old as the oldest rocks on the Moon.

• 16:54Chuck Nice?

  Exactly.

• 16:55Neil deGrasse Tyson?

  Because the Moon was done with its volcanic activity very early.

• 16:58Chuck Nice?

  Right.

• 16:59Neil deGrasse Tyson?

  And once you're done, your rocks-

• 17:00Chuck Nice?

  You're not remaking yourself.

• 17:01Neil deGrasse Tyson?

  You're not remaking yourself.

• 17:02Chuck Nice?

  Yeah, you're just sitting there.

• 17:03Neil deGrasse Tyson?

  You're just sitting there.

• 17:04Chuck Nice?

  But the Earth is kinda like our skin. Is that what you're saying? Kinda like-

• 17:08Neil deGrasse Tyson?

  I guess, I, you know, if you're a metrosexual and you get skin peels and things, fine. Uh, it's not my first thought, Chuck. Groomed Chuck. It's not my first thought, but yes, you're constantly remaking your outer epidermis, yes. Okay.

• 17:24Chuck Nice?

  I love that that's where my mind goes. To my next chemical peel. Alright, that was fast.

• 17:29Neil deGrasse Tyson?

  Next one, we only got like a minute.

• 17:30Chuck Nice?

  You got a minute? Okay, let me find something.

• 17:32Neil deGrasse Tyson?

  In this segment.

• 17:33Chuck Nice?

  Very quick. Uh, which will happen first? The expansion of the sun into a red giant? Or the death of the dynamo inside the earth? Leading to the loss of the earth's magnetic field?

• 17:43Neil deGrasse Tyson?

  Oh, uh, we'll probably lose our dynamo before the death of the earth, is what I'm saying. Dynamo is, is lingo for the movement of molten iron. And when you move metals in a, you, what you can do is, you can end up generating currents. And if you have a current, you also have a magnetic field. And this is what a dynamo is. It's the relationship between sort of moving electrons and the magnetic field that comes about as a result. By the way, that's how we create electricity to begin with.

• 18:15Chuck Nice?

  That's right.

• 18:15Neil deGrasse Tyson?

  Alright, we take wires, move it through a magnetic field. It, it works both ways. Moving current makes magnetic field, and magnetic field can induce a current to make electricity.

• 18:27Neil deGrasse Tyson?

  We got a break. When we come back, more of StarTalk Radio Cosmic Queries.

• 18:50Neil deGrasse Tyson?

  We're back on StarTalk Radio. You can find us on the net, StarTalkRadio.net. All our archive shows are there. We might have put the first season under, under wraps, but after that, they're, they're available to you.

• 19:03Chuck Nice?

  Excellent.

• 19:04Neil deGrasse Tyson?

  Yeah, and, uh, check it out. There's a lot, quite a bit of, uh, interesting shows from our archive.

• 19:09Chuck Nice?

  Absolutely.

• 19:09Neil deGrasse Tyson?

  That's the voice of Chuck Nice you're hearing, and he's reading me Cosmic Queries. I've never seen these. They come in on our, all of our, uh, social media portals.

• 19:17Chuck Nice?

  That's correct.

• 19:18Neil deGrasse Tyson?

  And, uh, give it to me. And the topic today is Earth. And I'm like astrophysicist, so to me it would be Earth as a planet, not Earth as a geologist.

• 19:26Chuck Nice?

  There you go.

• 19:27Neil deGrasse Tyson?

  Alright, so what do you have?

• 19:28Chuck Nice?

  Here we go, let's uh, let's move on to an email question. This is by Bud Sont.

• 19:32Neil deGrasse Tyson?

  Oh wait, wait. In a previous segment, someone asked, what would happen to life if the Earth's magnetic field changed?

• 19:38Chuck Nice?

  That's right, if our dynamo, we lost our dynamo.

• 19:40Neil deGrasse Tyson?

  If we lost it, I forgot to say, we have evidence that the magnetic field has gone away many times before.

• 19:45Chuck Nice?

  Oh.

• 19:46Neil deGrasse Tyson?

  Because it goes to zero as it flips. Our magnetic field has flipped several, many times in the past. It's flipped.

• 19:52Chuck Nice?

  So, okay, so it's happened then.

• 19:54Neil deGrasse Tyson?

  And so when it's flipped, it goes to zero. You can look at the fossil record, while we had zero magnetic field, they would Karen on making babies just fine. So, whatever is their version of a baby is just fine.

• 20:06Chuck Nice?

  It's just fine.

• 20:07Neil deGrasse Tyson?

  So, it does not appear to be as severe as you might think.

• 20:09Chuck Nice?

  Okay.

• 20:10Neil deGrasse Tyson?

  The evidence shows.

• 20:11Chuck Nice?

  That's good to know.

• 20:12Neil deGrasse Tyson?

  Yeah, alright, so what else you got?

• 20:13Chuck Nice?

  Uh, this is an email by Bud Sont, and Bud wants to know this. How does the northern hemisphere's high proportion of landmass affect the Earth's rotation?

• 20:24Neil deGrasse Tyson?

  Ooh, yeah, so, here, here, the, the, what's the fellow's name?

• 20:30Chuck Nice?

  This is Bud Sont.

• 20:31Neil deGrasse Tyson?

  Bud knows that most of the land of the Earth is in the northern hemisphere. It's like eighty percent of the land is in the northern hemisphere. And by the way, about eighty percent of the population, the human population is in the northern hemisphere as well.

• 20:45Chuck Nice?

  Right.

• 20:45Neil deGrasse Tyson?

  So, we tend to live where the land is.

• 20:49Chuck Nice?

  Help us Aquaman!

• 20:52Neil deGrasse Tyson?

  FYI on that one. So, Earth has a rotation rate that is endowed by the distribution of matter on our surface and throughout the solid ball, alright? If you were to change the distribution of matter, if you were to move continents from the northern hemisphere into the south, towards the equator, away from the equator, you will change what's called the moment of inertia of the Earth.

• 21:20Chuck Nice?

  The moment of inertia?

• 21:21Neil deGrasse Tyson?

  That's, it's a physics term.

• 21:22Chuck Nice?

  Of the Earth.

• 21:22Neil deGrasse Tyson?

  If you change the moment of inertia, Earth's rotation rate will change with it.

• 21:27Chuck Nice?

  Okay.

• 21:28Neil deGrasse Tyson?

  And, by the way, skaters do this. When they pull their arms in- They are changing their own moment of inertia and what happens to their rotation rate?

• 21:35Chuck Nice?

  They go faster.

• 21:35Neil deGrasse Tyson?

  They go faster. And by the way, how do they stop?

• 21:38Chuck Nice?

  They put their arms out.

• 21:39Neil deGrasse Tyson?

  Back out and they can stop on a dime. Right? They change their rotation rate by bringing the arms in or out. If you move continents towards the equator, away from the equator, into the southern hemisphere, towards the northern hemisphere, you are changing the moment of inertia. Our rotation rate will change and you can calculate how much we change after every earthquake. Because an earthquake is a redistribution of the of the continental shelves.

• 22:02Chuck Nice?

  Wow.

• 22:03Neil deGrasse Tyson?

  Yeah.

• 22:04Chuck Nice?

  And so we would actually change our days and nights.

• 22:07Neil deGrasse Tyson?

  The length of the day. You can make it longer or shorter.

• 22:10Chuck Nice?

  Moment of inertia change.

• 22:11Neil deGrasse Tyson?

  Exactly. In fact, melting glaciers changes on the rotation rate of the earth.

• 22:15Chuck Nice?

  What?

• 22:16Neil deGrasse Tyson?

  Yep, because you have mass in one location and then it melts and moves to another location on earth.

• 22:21Chuck Nice?

  Gotcha.

• 22:22Neil deGrasse Tyson?

  Yeah.

• 22:23Chuck Nice?

  Awesome. Wow, man.

• 22:25Neil deGrasse Tyson?

  They all they also change the rotation rate because the glaciers are on land. And so not only will the the mass redistribute, it also moves from high altitude to sea level. Okay, so now you're changing how far away the matter is from the rotation axis of the earth. All this conspires to influence our rotation rate.

• 22:45Chuck Nice?

  I, you know what? I gotta tell you, I never thought you would give that much information from that. That is awesome.

• 22:55Neil deGrasse Tyson?

  Yeah.

• 22:56Chuck Nice?

  All right, all right, what else? Move on. Uh, let's go back to Facebook.

• 22:59Neil deGrasse Tyson?

  Okay.

• 22:59Chuck Nice?

  And this is Brian Engel from Facebook. Uh, if the moon is constantly getting farther away from the earth every year.

• 23:06Neil deGrasse Tyson?

  About two inches a year.

• 23:07Chuck Nice?

  Okay, so about two inches a year. Then why do we have a super moon where the moon appears larger?

• 23:15Neil deGrasse Tyson?

  Okay, first, I gotta nip this in the bud.

• 23:17Chuck Nice?

  Okay.

• 23:18Neil deGrasse Tyson?

  Don't get me started.

• 23:19Chuck Nice?

  I'm getting you started.

• 23:20Neil deGrasse Tyson?

  Don't get me started.

• 23:20Chuck Nice?

  I gotta get you started here.

• 23:21Neil deGrasse Tyson?

  All right, so we there's something called a super moon?

• 23:24Chuck Nice?

  Okay.

• 23:24Neil deGrasse Tyson?

  I don't know who first called it a super moon.

• 23:26Chuck Nice?

  All right.

• 23:27Neil deGrasse Tyson?

  I don't know, but if you have a 16 inch pizza, would you call that a super pizza compared with a 15 inch pizza?

• 23:36Chuck Nice?

  Uh, how many meat toppings are we talking? Cause if we're talking like totally loaded, then yes, I'm going with yes.

• 23:42Neil deGrasse Tyson?

  And is the cheese in the crust?

• 23:43Chuck Nice?

  Right, if the cheese in the crust.

• 23:44Neil deGrasse Tyson?

  Alright, the super moon is a 16 inch pizza compared with a 15 inch pizza. It's a slightly bigger moon. I ain't using the adjective super.

• 23:52Chuck Nice?

  Super moon.

• 23:52Neil deGrasse Tyson?

  Nah, uh, excuse me.

• 23:53Chuck Nice?

  That's like super Tuscan.

• 23:55Neil deGrasse Tyson?

  I'm not going there. Super Tuscan wines.

• 23:57Chuck Nice?

  Right.

• 23:57Neil deGrasse Tyson?

  Yes. Yes, they're super because they're super priced.

• 24:02Neil deGrasse Tyson?

  They cost like four or five times regular. You, you pay like a hundred bucks to a very, very, right? So, uh, where was I before? Why are we talking about wine? I'm talking about the universe here. You bring up Tuscan wine.

• 24:13Chuck Nice?

  Uh, you know, what can I say? I'm always thinking about wine. So there is no super moon is what you're saying.

• 24:18Neil deGrasse Tyson?

  So the super moon is, the moon's orbit around the earth is not a perfect circle. Sometimes it's closer, sometimes it's farther away.

• 24:25Chuck Nice?

  Gotcha.

• 24:26Neil deGrasse Tyson?

  At every month, there's a moment when it's closest.

• 24:29Chuck Nice?

  Gotcha.

• 24:29Neil deGrasse Tyson?

  Occasionally, that moment when it's closest coincides with a full moon. People are calling that a super moon. I, but there's super half moons, alright? There's not, every month, so one of those phases is the closest. I don't hear people that, oh, a super crescent, super half moon, super, no! No! Don't get, I told you, don't get me started. Not only that, I was gonna tweet this, but I'm gonna say it here now first.

• 24:53Chuck Nice?

  Okay, go ahead.

• 24:54Neil deGrasse Tyson?

  Do you know, the full moon has no higher tidal effect on earth than any other phase of the moon?

• 25:01Chuck Nice?

  Now you're just making stuff up.

• 25:03Neil deGrasse Tyson?

  Alright, when we come back, more StarTalk, Cosmic Queries.

• 25:25Neil deGrasse Tyson?

  We're back. StarTalk.

• 25:28Neil deGrasse Tyson?

  We're themed today with questions on the earth.

• 25:33Chuck Nice?

  Yes.

• 25:34Neil deGrasse Tyson?

  Now, do I look like an earth expert to you?

• 25:36Chuck Nice?

  You know, I gotta tell you, as long as I've known you, I'm, I don't know pretty much anything you're not an expert on. Seriously, I'm serious when I say I'm not even blowing smoke.

• 25:46Neil deGrasse Tyson?

  Somehow producers thought we would have a, wouldn't it be nice if we had earth questions? So I can answer earth questions, earth as a planet, not earth as a geologist.

• 25:53Chuck Nice?

  Right. Hey, before we go for it, I just, I, cause I need you to clear something up, man.

• 25:57Neil deGrasse Tyson?

  What?

• 25:58Chuck Nice?

  I'm serious, Neil.

• 25:59Neil deGrasse Tyson?

  What?

• 25:59Chuck Nice?

  Okay, you said that there's no effect that the moon has on, on the titles. I mean, a bigger full moon on, sorry, let me say this again. You said there's no effect a full moon has on the tides than any other moon.

• 26:11Neil deGrasse Tyson?

  Yeah, that's correct.

• 26:12Chuck Nice?

  When, when, when.

• 26:13Neil deGrasse Tyson?

  And you couldn't let it go, you couldn't?

• 26:15Chuck Nice?

  No, because when Sandy came, I believe you, but I'm just saying, there's a lot of people out there who's gonna have a problem with this. Cause the news when Sandy happened.

• 26:23Neil deGrasse Tyson?

  Okay.

• 26:24Chuck Nice?

  Hurricane Sandy, they talked all about the, the tidal effects of the moon and it was a full moon.

• 26:30Neil deGrasse Tyson?

  Yeah, okay.

• 26:30Chuck Nice?

  This is why Sandy was so.

• 26:32Neil deGrasse Tyson?

  There are only two things that affect the tides from the moon. You ready?

• 26:36Chuck Nice?

  Go ahead.

• 26:36Neil deGrasse Tyson?

  The mass of the moon, is that changing?

• 26:38Chuck Nice?

  That never changes.

• 26:39Neil deGrasse Tyson?

  Okay, is the, is the mass of the moon higher at full moon than at half moon?

• 26:42Chuck Nice?

  No, it's the same moon.

• 26:43Neil deGrasse Tyson?

  A, B, the distance to the moon, okay? The moon orbits us, sometimes it's closer, sometimes it's farther away, that has nothing to do with the phase. It's an elliptical orbit, sometimes it's closest to full moon, sometimes it's not. But it's not, okay?

• 26:55Chuck Nice?

  Right.

• 26:55Neil deGrasse Tyson?

  Those are the only two things that affect the strength of the tides on earth from the moon.

• 27:00Chuck Nice?

  Okay.

• 27:00Neil deGrasse Tyson?

  So, so why do we have a higher tide during full moon? Because the sun's tides add to the full moon's tide.

• 27:08Chuck Nice?

  I got it.

• 27:08Neil deGrasse Tyson?

  To the moon's tide.

• 27:09Chuck Nice?

  So it's the sun?

• 27:10Neil deGrasse Tyson?

  It's the sun, blame the sun.

• 27:11Chuck Nice?

  Blame the sun.

• 27:11Neil deGrasse Tyson?

  Blame Sandy on the sun, not the poor moon that dutifully orbits us every month of the year.

• 27:17Chuck Nice?

  Fantastic.

• 27:18Neil deGrasse Tyson?

  Don't blame the moon on that one. What's next? Okay, well, we have a phone call. We got a phone call. And we have Blake, who I believe is a soldier at Fort Bragg. Ooh. Yes. Is this Blake on the line?

• 27:32Speaker 03

  Yes, it is, Dr. Tyson.

• 27:33Neil deGrasse Tyson?

  Blake, you call me doctor, I gotta call you by your title. What are you?

• 27:37Speaker 03

  Uh, War Officer One.

• 27:40Neil deGrasse Tyson?

  Uh, One Officer One. One Officer One?

• 27:44Speaker 03

  Mister.

• 27:45Neil deGrasse Tyson?

  Mister. Oh, okay. Okay, no, no, he said yes, sir. Okay, so Blake, what do you have for me? Call me Neil, please, please.

• 27:52Speaker 03

  Yes, sir, Neil. Um, my question...

• 27:56Neil deGrasse Tyson?

  These military guys, you can't get the sir out of them. That's great. All right, so what do you have?

• 28:00Speaker 03

  No, you can't. Um, my question has to do with the gravity of the Earth. If the Earth had been born with twice the, twice the size, it would have twice the gravity, and anything that evolved on the planet would have evolved in that double time gravity that we currently have. Is there any upper limits to a Earth-like planet where carbon-based life forms just wouldn't have been able to evolve because of the massive gravity?

• 28:25Neil deGrasse Tyson?

  That's a brilliant question. That really is. It is, it is. So, a couple of things. If Earth were sort of twice our size, we would have eight times the mass. Okay, because the volume goes up as the cube of the thing, so that's two cubed would give you eight. Right. So, so the surface gravity then is a combination of how far, how much farther away we are from the center of the Earth, and how much extra mass is there. So, you can do the math, but you can just assert, make an Earth that has twice the gravity. Here's what will happen. Everybody's legs would be more squat.

• 28:59Neil deGrasse Tyson?

  First of all, okay? So, everyone would look a little bit more like a hippopotamus, all right? Or dwarf. You probably, well, dwarfs, right. You wouldn't, things wouldn't grow as tall. Giraffes would have thicker legs, horses would be shorter, all of that would happen, okay? The giraffe has very high blood pressure to get blood to its brain to go up to all the vertebrae of its neck. And so, if you have twice the gravity, you would need... Twice the pressure to get it up there and that could blow your blood vessels. So you'd have shorter giraffes. So you wouldn't have any of these tall creatures. But you didn't ask about mammals. You asked about carbon based life. Most of the biomass on earth could care less.

• 29:40Neil deGrasse Tyson?

  Couldn't care less what the force of gravity was on earth. Period. All the life in the ocean is neutrally buoyant. That's right. It doesn't care. Bacteria swimming in the pond. In the pond, what do you, the pond drop. You know, you'd look at it when you're in high school, you look at. The petri dish? You'd get a drop of water from the pond and you see paramecium in it thriving. They don't care about gravity. That's right. Their lives, they thrive under like the surface tension of the water. So most life actually does not care about gravity. We do. Because we're out here on the land. Out here on the land, we're trying to jump. Olympics would be kind of different. There'd be no hurdling.

• 30:25Neil deGrasse Tyson?

  No, there'd be the low hurdles, not the high hurdles. So yeah, so sports would be very different, but a factor of two gravity, not a problem for life. Right. And you'd have sort of more, sort of smaller life thriving than bigger life. And that's about it. Wow. Yeah. There you go Blake. So thanks Blake for that one. Thank you very much. All right. You're listening to StarTalk Radio, the Cosmic Queries Edition. Today's topic, the earth. We'll see you in a moment.

• 31:09Neil deGrasse Tyson?

  This is StarTalk Radio.

• 31:13Neil deGrasse Tyson?

  The lightning round. Chuck, you know what the rules are.

• 31:16Chuck Nice?

  Oh, yeah.

• 31:17Neil deGrasse Tyson?

  You're gonna read me questions, rapid fire. I'm gonna give you soundbite answers. I haven't heard the questions before.

• 31:21Chuck Nice?

  That's correct.

• 31:22Neil deGrasse Tyson?

  And we invented the lightning round because we never got through all the questions.

• 31:25Chuck Nice?

  Right, so this is a way of getting to everybody's question.

• 31:27Neil deGrasse Tyson?

  Uh, one, just one follow up on that last bit about from the soldier at Fort Bragg.

• 31:32Chuck Nice?

  Mm-hmm.

• 31:32Neil deGrasse Tyson?

  He had asked about the doubling Earth's gravity. Uh, and I said, ocean life wouldn't care.

• 31:38Chuck Nice?

  Right.

• 31:38Neil deGrasse Tyson?

  But I should have commented, water then weighs twice as much. So if you're accustomed to swimming at a particular depth, you then swim at half that depth.

• 31:46Chuck Nice?

  Gotcha.

• 31:47Neil deGrasse Tyson?

  That way, the weight of the water above you would be the same as it was in the previous Earth.

• 31:51Chuck Nice?

  Right.

• 31:51Neil deGrasse Tyson?

  Right, that's all.

• 31:52Chuck Nice?

  Okay.

• 31:52Neil deGrasse Tyson?

  I just wanted to like, straighten that out.

• 31:53Chuck Nice?

  Okay, okay.

• 31:54Neil deGrasse Tyson?

  And they could easily find that place, right? There are fishes and they move in three dimensions.

• 31:58Chuck Nice?

  Exactly.

• 31:58Neil deGrasse Tyson?

  There you go.

• 31:59Chuck Nice?

  Right.

• 31:59Neil deGrasse Tyson?

  All right. All right, lightning round. Let's do this. I have a bell?

• 32:03Chuck Nice?

  Where's your bell?

• 32:04Neil deGrasse Tyson?

  Here.

• 32:04Chuck Nice?

  Let's get it out.

• 32:05Neil deGrasse Tyson?

  There it is. There's the bell.

• 32:06Chuck Nice?

  All right, here we go. Are we ready?

• 32:08Neil deGrasse Tyson?

  Yes.

• 32:08Chuck Nice?

  All right.

• 32:08Neil deGrasse Tyson?

  Let me test it.

• 32:09Chuck Nice?

  Yep.

• 32:09Neil deGrasse Tyson?

  There we go.

• 32:10Chuck Nice?

  Okay, we're good to go.

• 32:11Neil deGrasse Tyson?

  Mm-hmm.

• 32:11Chuck Nice?

  This is from Justin Keeney. How large would an object have to be to impact the Earth and alter its orbit around the Sun? I'm gonna change that to, is there an object large enough to do that?

• 32:23Neil deGrasse Tyson?

  Anything that hits Earth alters our orbit. The question is, is it altering it in any significant way? There is nothing on a collision course that will have any significant impact on Earth's orbit around the Sun. And odd that he's worried about our orbit around the Sun and not on our survival

• 32:39Chuck Nice?

  I was gonna say.

• 32:40Neil deGrasse Tyson?

  from such a collision.

• 32:40Chuck Nice?

  Yeah, because such a collision will wipe us out.

• 32:42Neil deGrasse Tyson?

  You'll go extinct and Earth's orbit will be just fine.

• 32:44Chuck Nice?

  There you go.

• 32:45Neil deGrasse Tyson?

  Mm-hmm.

• 32:45Chuck Nice?

  All right.

• 32:46Neil deGrasse Tyson?

  Uh, by the way, in the early solar system, there was such stuff that would have knocked our orbit well out of whack. But all that's been absorbed up and vacuumed up by all the other planets and we are in a mature looking solar system.

• 32:57Chuck Nice?

  Hey, thanks Jupiter for taking one for the team.

• 32:59Neil deGrasse Tyson?

  Taking one for the team. You got it. Jupiter ate most of it.

• 33:01Chuck Nice?

  There you go. Leon Bruce, uh, wants to know this. If we continue to leave scraps, debris in space from our satellites and such, would we ever develop a ring such as Saturn?

• 33:16Neil deGrasse Tyson?

  A debris ring?

• 33:17Chuck Nice?

  A debris ring!

• 33:19Neil deGrasse Tyson?

  Uh, so the low hanging, uh, debris will... re-enter Earth's atmosphere cuz it'll get friction from the air. If it's very high up, it'll never go away ever. And we already have a ring of debris. It's at the twenty-two thousand miles up where we put the communication satellites. They're in a ring over the equator of the Earth, so we already have rings.

• 33:40Chuck Nice?

  Well, we already have a ring.

• 33:41Neil deGrasse Tyson?

  Yeah, yeah. And it's not big enough like Saturn's rings, but if we kept it, kept at it, because when a satellite dies, we just lift it up a little higher and to make room for another satellite to take it away. So to keep this up.

• 33:51Chuck Nice?

  There's a bunch of dead satellites floating above us.

• 33:54Neil deGrasse Tyson?

  Deathlight too far away to re-enter the atmosphere and then just stay there forever.

• 33:58Chuck Nice?

  Forever.

• 33:59Neil deGrasse Tyson?

  Yes, we are creating our own Saturnian ring around the Earth system.

• 34:02Chuck Nice?

  Nice, nice. Okay, Susan Hammack wants to know this. I know that atmospheric pollution contributes to the colors we see in the sunset and sunrise. What would those sunsets and sunrises look like during prehistoric times with no man-made pollution? Would they still have been red and orange?

• 34:25Neil deGrasse Tyson?

  First of all, women are making pollution too, so don't be blaming men for that. A. B, it's not only pollution, it's pollen. It's water vapor, it's dust kicked up from deserts.

• 34:36Chuck Nice?

  All kinds of particles.

• 34:37Neil deGrasse Tyson?

  Volcanic particles. All those particles make a sunset red cuz all the colors from the sun are red, orange, yellow, green, blue, violet. Mix them together, it is white light.

• 34:45Chuck Nice?

  Right.

• 34:46Neil deGrasse Tyson?

  Those particles scatter out of the sunbeam, all the blue, that's why we have a blue sky.

• 34:51Chuck Nice?

  Right.

• 34:51Neil deGrasse Tyson?

  And the more it scatters, the deeper the yellow, orange, red the sun appears. So that when you have maximal scattering, that's right at sunset when the sun is deepest red and the sky is deepest blue. So dinosaurs would have totally enjoyed red sunsets in their day. Without the benefit of our pollution.

• 35:08Chuck Nice?

  Notes. So red sunsets, just breathing easier.

• 35:12Neil deGrasse Tyson?

  That's right, exactly.

• 35:13Chuck Nice?

  There you go. Awesome.

• 35:14Neil deGrasse Tyson?

  All right.

• 35:15Chuck Nice?

  Um, let's move on to Felipe Santiago. Felipe wants to know this. Could a cataclysm like the one that destroyed Krypton occur in reality? Can a planet explode from within? And what would be the reason?

• 35:32Neil deGrasse Tyson?

  So, we're talking about Superman's home planet.

• 35:35Chuck Nice?

  Krypton.

• 35:36Neil deGrasse Tyson?

  Okay, if we remember from the film, they overmined the planet, made the core unstable, and then the planet collapsed and then exploded.

• 35:44Chuck Nice?

  Correct.

• 35:45Neil deGrasse Tyson?

  We are not overmining our planet to destabilize the planet. We're overmining our planet to destabilize our atmosphere. That's different. So, no, we're nowhere close to that ever happening here on Earth. But if you start taking whole chunks of the inside of the Earth out, yeah, you're gonna start collapsing. You're gonna have some serious sinkholes on your hand. Will we explode? No, the energy isn't enough to explode the Earth and have us scatter into space.

• 36:08Chuck Nice?

  Hmm, so the answer is we won't explode, but there's still hope for the cataclysm.

• 36:13Neil deGrasse Tyson?

  All right, next.

• 36:16Chuck Nice?

  Let's...

• 36:16Neil deGrasse Tyson?

  All right. Quick.

• 36:18Chuck Nice?

  Okay.

• 36:18Neil deGrasse Tyson?

  I got one minute, go.

• 36:19Chuck Nice?

  Here we go, one minute. All right, here we go. Mike McGill wants to know this. What's the most unexpected and less well-known danger we are exposed to as a planet from the cosmos?

• 36:31Neil deGrasse Tyson?

  Ooh, well, in the year 1900?

• 36:33Chuck Nice?

  Uh huh.

• 36:34Neil deGrasse Tyson?

  And you ask people, what are you most worried about? They're worried about overpopulation and lack of food and all of this. They were not worried about asteroids.

• 36:40Chuck Nice?

  So true.

• 36:41Neil deGrasse Tyson?

  They didn't learn about asteroids yet.

• 36:43Chuck Nice?

  And we know about them.

• 36:43Neil deGrasse Tyson?

  Well, now we know about them. So I ask myself, there's the known knowns, and how about the unknown unknowns? In a century, what will people be listing as the biggest risk to their lives? We have no idea. That's why it's good to kind of learn what's out there. Don't be saying, oh, I'm just looking at Earth, that's all I care about. No, because the end of your life may come from space.

• 37:04Chuck Nice?

  Learn something, dummy.

• 37:05Neil deGrasse Tyson?

  Well, we gotta go. This has been StarTalk Cosmic Queries Edition. Chuck Nice, thanks as always for being my co-host here.

• 37:12Chuck Nice?

  My pleasure.

• 37:12Neil deGrasse Tyson?

  I'm Neil deGrasse Tyson, your personal astrophysicist, thanking the National Science Foundation for their support, in part for the production of this program. As always, I bid you to keep looking up.