WEBVTT - Asteroid 2019 OK: The Little Doomsday 0:00:03.000 --> 0:00:04.960 Welcome Stuff to Blow Your Mind, a production of I 0:00:05.000 --> 0:00:13.920 Heart Radios How Stuff Works. Hey, you welcome to Stuff 0:00:13.920 --> 0:00:15.840 to Blow your Mind. My name is Robert Lamb and 0:00:15.920 --> 0:00:18.280 I'm Joe McCormick. You know, we've been talking a lot 0:00:18.360 --> 0:00:24.360 recently about you know, some perhaps more ambiguous risks to humanity, 0:00:25.000 --> 0:00:29.720 but but not so much the ambiguity in this episode. Wait, 0:00:29.720 --> 0:00:31.680 what are the ambiguous risks? Oh, you know we're talking 0:00:31.720 --> 0:00:34.120 about like you know, you're getting talking about like social 0:00:34.120 --> 0:00:37.840 media and how and how it's affecting the human condition 0:00:38.120 --> 0:00:40.760 or you know, certainly in our episodes on psychedelics, you know, 0:00:40.800 --> 0:00:44.040 we talked about some of the more ambiguous and even 0:00:44.040 --> 0:00:48.160 more concrete threats facing humanity and to what extent some 0:00:48.280 --> 0:00:51.800 commentators think that the psychedelic experience can prepare us for 0:00:51.840 --> 0:00:55.280 those threats. Okay, so kind of vague possible psychic and 0:00:55.320 --> 0:00:59.360 cultural threats, right, yeah, less less threats like a huge 0:00:59.480 --> 0:01:03.000 rock hitting you. Right, because because we over good, what 0:01:03.040 --> 0:01:05.080 we're gonna be talking about the day is certainly the 0:01:05.160 --> 0:01:08.080 kind of threat that that a mushroom is not going 0:01:08.120 --> 0:01:09.959 to be able to help us with. Right, So we 0:01:10.000 --> 0:01:13.720 wanted to talk about an interesting, perhaps hair raising story 0:01:14.240 --> 0:01:18.240 from recent Space News. So, just within the past couple 0:01:18.280 --> 0:01:22.399 of weeks, Earth had a very close encounter and almost 0:01:22.600 --> 0:01:27.240 perfectly timed intersection with the orbit of a fast moving 0:01:27.280 --> 0:01:31.680 object from outer space. And the creepy and fascinating thing 0:01:31.680 --> 0:01:34.240 about this is that this object came very close to 0:01:34.280 --> 0:01:37.600 Earth and we had almost no forewarning that it was coming. 0:01:38.120 --> 0:01:40.840 So what was this thing? Well, I actually first saw 0:01:40.880 --> 0:01:44.280 it when Robert shared an article about it on on 0:01:44.360 --> 0:01:47.800 social media. That's right, Yeah, there we go, determining the 0:01:47.800 --> 0:01:50.320 topics of all conversation. Well, and the crazy thing about 0:01:50.320 --> 0:01:52.240 it is that, you know, as we've discussed in the show, 0:01:52.280 --> 0:01:54.800 and the the more extreme things get to know, the rise 0:01:54.880 --> 0:01:57.600 to the surface and social media and especially right now, 0:01:57.680 --> 0:02:01.640 it tends to be stuff related to politics. But then somehow, uh, 0:02:01.800 --> 0:02:05.800 this one story breached the surface. It may have helped 0:02:05.880 --> 0:02:09.200 that it had the word killer in the headline. So 0:02:09.280 --> 0:02:14.440 this was an asteroid that is now officially called asteroid nineteen. Okay, 0:02:14.520 --> 0:02:17.520 and that doesn't mean it's okay, that's just a you know, 0:02:17.639 --> 0:02:19.880 that's the code assigned to it. I read it as 0:02:20.200 --> 0:02:25.000 asteroid two thousand, nineteen, Okay, it's kind of like that. 0:02:25.360 --> 0:02:28.320 So it was detected by astronomers in Brazil and the 0:02:28.400 --> 0:02:33.400 United States before being confirmed by NASA JPL and on July. 0:02:35.360 --> 0:02:38.520 It passed by Earth at a speed of about twenty 0:02:38.560 --> 0:02:43.320 four kilometers per second, which is like fifty four thousand 0:02:43.440 --> 0:02:46.679 miles per hour. Pretty fast. And what we want to 0:02:46.680 --> 0:02:50.040 emphasize is it's already gone, okay, so we should emphasize 0:02:50.080 --> 0:02:53.520 that at the beginning, this asteroid represents zero threat to 0:02:53.680 --> 0:02:57.079 us on any meaningful time scale. It is passed, it's 0:02:57.120 --> 0:02:59.679 on its way to other things. And the reason we're 0:02:59.680 --> 0:03:01.959 talking about this is that I feel like this event 0:03:02.080 --> 0:03:06.160 is instructive. It shows the real life and death importance 0:03:06.200 --> 0:03:10.160 of astronomy in general and improving our capabilities for cataloging 0:03:10.280 --> 0:03:14.400 near Earth objects more specifically. And it's also I think 0:03:14.440 --> 0:03:17.120 an event that really reveals the part of you that 0:03:17.200 --> 0:03:21.200 either leans towards the positive or the negative interpretation of things, 0:03:21.360 --> 0:03:24.160 you know, the glass half full half empty kind of thing, right, 0:03:24.320 --> 0:03:27.600 the near miss versus near hit. Yeah, and also reminded 0:03:27.600 --> 0:03:29.520 of the old adage. You know, I don't know if 0:03:29.560 --> 0:03:32.760 it's truly an adage, but the observation that you never 0:03:32.840 --> 0:03:34.720 hear the one that has your name on it. You know, 0:03:34.760 --> 0:03:37.520 generally talking about say, you know, a bullet in a military, 0:03:37.880 --> 0:03:40.600 uh situation. It's like on the Sopranos, you know, you 0:03:40.640 --> 0:03:42.800 never know the one that's coming for you, right. But 0:03:43.040 --> 0:03:45.640 the thing is we are we are in the business 0:03:45.800 --> 0:03:48.680 right now of trying to know the ones that have 0:03:48.760 --> 0:03:51.920 our name on it, the the asteroids particularly that have 0:03:52.640 --> 0:03:56.920 that that have Earth or possibly Earth printed on their side. Yeah, 0:03:57.000 --> 0:03:59.240 and it's always going to be a probabilistic thing when 0:03:59.240 --> 0:04:02.320 we're looking to far out, so you wouldn't know for sure, 0:04:02.360 --> 0:04:04.320 but you'd say, you know, we think there's a you know, 0:04:04.640 --> 0:04:07.880 zero point whatever percent chance this has Earth on its name, 0:04:08.280 --> 0:04:11.520 has Earth's name on it, or maybe has a chance 0:04:11.680 --> 0:04:13.240 right yet to be clear. And we'll get into some 0:04:13.320 --> 0:04:16.400 of the statistics here in a bit. But there there 0:04:16.400 --> 0:04:20.200 are no asteroids out there right now that that Nassa 0:04:20.279 --> 0:04:23.839 or anyone else is saying this is a definite collision course. 0:04:24.160 --> 0:04:26.320 No no big ones, No big ones. So yeah, I mean, 0:04:26.360 --> 0:04:28.600 obviously they are ones that are going to imbact Us 0:04:28.600 --> 0:04:31.279 and with with with a little or no effect. But 0:04:31.320 --> 0:04:34.919 in terms of like really big problematic asteroids, the ones 0:04:34.960 --> 0:04:37.159 that are the ones that we know of, and it 0:04:37.279 --> 0:04:38.960 is a you know, just a segment of the ones 0:04:39.000 --> 0:04:41.520 that are out there. There are none that we are 0:04:41.560 --> 0:04:43.919 like positive like, this is the one. This is the 0:04:43.960 --> 0:04:46.600 one we have to act on right now, right now. Yeah, 0:04:46.720 --> 0:04:49.840 but this twenty nineteen, Okay, asteroids. So first of all, 0:04:49.920 --> 0:04:52.080 the question we need to play the glass half full 0:04:52.120 --> 0:04:55.559 half empty thing with Was it big or was it small? Well, 0:04:55.600 --> 0:04:58.240 it was between we think about fifty seven and a 0:04:58.360 --> 0:05:01.320 hundred and thirty meters in diameter, which is a hundred 0:05:01.320 --> 0:05:04.440 and eighty seven to four hundred and twenty seven feet. 0:05:05.160 --> 0:05:07.360 Is that big or is that small? Well, it depends 0:05:07.360 --> 0:05:10.200 on what you compare it to the object that struck 0:05:10.240 --> 0:05:13.040 the Earth sixty six million years ago, the impact that 0:05:13.320 --> 0:05:15.520 most likely played a major role in the extinction of 0:05:15.520 --> 0:05:18.839 the dinosaurs. That one was probably I've seen estimates of 0:05:18.839 --> 0:05:21.560 ten to fifteen kilometers across. I've seen that people say 0:05:21.600 --> 0:05:23.880 more recently, this might be an updated or more more 0:05:23.920 --> 0:05:27.880 precise figure that it was like fifteen or sixteen kilometers across. 0:05:28.000 --> 0:05:30.560 That's obviously a lot bigger. We're we're talking this object 0:05:30.640 --> 0:05:32.640 that just went past us is a couple of orders 0:05:32.680 --> 0:05:35.760 of magnitude smaller than that. So we're not talking about 0:05:35.800 --> 0:05:39.320 like necessarily a full blown civilization buster. No no, no 0:05:39.440 --> 0:05:44.360 extinction event level impact. Yeah. Unfortunately, astronomers believe that more 0:05:44.440 --> 0:05:48.920 than nine percent of objects in this extinction event size 0:05:48.960 --> 0:05:52.360 category category, the category of things on the scale of 0:05:52.400 --> 0:05:55.840 the asteroid that killed the dinosaurs, uh, things like that, 0:05:56.000 --> 0:05:59.440 more than nine percent in our orbital vicinity have already 0:05:59.480 --> 0:06:02.520 been disc covered and cataloged by NASA and other observers 0:06:02.520 --> 0:06:05.960 and space agencies because the bare ones are simply easier 0:06:06.000 --> 0:06:08.600 to spot, right exactly, And so for the biggest of 0:06:08.640 --> 0:06:10.560 the biggest, we're pretty sure we know where they are, 0:06:11.080 --> 0:06:13.120 uh that, and that we would be able to predict 0:06:13.200 --> 0:06:15.880 if they're headed our way, which is good, right, But 0:06:15.920 --> 0:06:18.240 then again, you could compare it to something on the 0:06:18.279 --> 0:06:21.640 other side. So the Chelly bents Comedia, which exploded in 0:06:21.680 --> 0:06:26.000 the atmosphere over Russia in was only about twenty meters 0:06:26.160 --> 0:06:29.680 in diameter, just twenty And this meteor was not even 0:06:29.760 --> 0:06:31.960 large enough to reach the ground. It didn't hit the 0:06:32.000 --> 0:06:35.760 surface of the Earth like most smaller objects entering our 0:06:35.800 --> 0:06:39.360 atmosphere from space. It exploded in the atmosphere and what's 0:06:39.400 --> 0:06:42.920 known as an air burst. And this this explosion injured 0:06:42.960 --> 0:06:45.960 over a thousand people. I think it was close to people. 0:06:46.360 --> 0:06:50.159 It damaged buildings, it collapsed roofs, it smashed windows in 0:06:50.200 --> 0:06:53.520 this big elliptical impact zone stretched out for dozens of 0:06:53.560 --> 0:06:56.400 kilometers um and and a lot of the damage and 0:06:56.480 --> 0:06:59.120 human injuries from this air blast were due to like 0:06:59.279 --> 0:07:02.600 blown out glass from windows hitting people. I should say. 0:07:02.640 --> 0:07:07.000 The footage also, of course, was incredible and certainly certainly 0:07:07.000 --> 0:07:08.839 makes you feel like a primate when you watch it. 0:07:08.920 --> 0:07:13.440 You feel like an earth bound primate um that has 0:07:13.560 --> 0:07:16.240 no control over the great fiery mass that is just 0:07:16.400 --> 0:07:18.960 seared across the horizon. It's a it's a two thousand 0:07:18.960 --> 0:07:23.400 one of space Odyssey monolith kind of thing. Yeah, you're like, well, okay, 0:07:23.440 --> 0:07:27.920 should I worship that? Maybe? But so that one, the 0:07:27.920 --> 0:07:30.480 one that caused all that damage, was just twenty wide. 0:07:30.800 --> 0:07:33.360 This this one that just passed us was somewhere between 0:07:33.400 --> 0:07:36.080 fifty seven and a hundred and thirty meters. Why that's 0:07:36.520 --> 0:07:39.360 a good bit bigger. It's somewhere between an extinction event 0:07:39.440 --> 0:07:42.720 level asteroid or object and you know, one of the 0:07:42.960 --> 0:07:45.760 smaller ones like we've seen with Cheli Bensk. In fact, 0:07:46.640 --> 0:07:49.200 the size of this thing that just passed us is 0:07:49.200 --> 0:07:53.040 probably roughly comparable to the size of something we're gonna 0:07:53.080 --> 0:07:55.400 talk about more in a bit, the meteor that exploded 0:07:55.440 --> 0:07:58.760 over Siberia in nineteen o eight and the event known 0:07:58.800 --> 0:08:01.520 as the Tunguska in impact. And like I said, well, 0:08:01.680 --> 0:08:04.960 we'll come back to that later. But basically though, the 0:08:05.640 --> 0:08:09.760 issue is it depends on where it hits. Y. Yeah, 0:08:09.840 --> 0:08:12.320 the thing that just passed us. The point is that 0:08:12.800 --> 0:08:15.480 it poses no threat to us. It's already gone. But 0:08:15.640 --> 0:08:19.120 if it had hit Earth, that would be really scary 0:08:19.240 --> 0:08:21.520 on the off chance that it came anywhere near a 0:08:21.560 --> 0:08:24.600 populated area. And of course the location is important with 0:08:24.640 --> 0:08:27.640 any of these. I mean, I've I've read arguments that 0:08:27.720 --> 0:08:32.280 the chicks a lube impact, Like if it had hit uh, 0:08:32.320 --> 0:08:34.680 if it had been a water impact as opposed to 0:08:34.679 --> 0:08:37.440 a land impact, Um, you know, it would have made 0:08:37.480 --> 0:08:41.120 some difference in what occurred. So that's that's going to 0:08:41.160 --> 0:08:45.600 be a factor no matter what scale you're talking about here. Absolutely, yeah, 0:08:45.679 --> 0:08:47.440 that that place a big role. Well, we'll talk more 0:08:47.440 --> 0:08:50.040 about that as we go on. So uh So we 0:08:50.080 --> 0:08:53.439 talked about the size, Another question is how close exactly 0:08:53.559 --> 0:08:56.360 did it come to Earth? Because there are the simulations 0:08:56.440 --> 0:08:58.760 that you can watch online. You should look this up. Actually, 0:08:58.800 --> 0:09:02.520 that show like the orbital pathways of Earth and this 0:09:02.800 --> 0:09:07.120 asteroid and as they sort of approach each other, as 0:09:07.160 --> 0:09:10.439 the intersection of these two orbital pathways comes up, it'll 0:09:10.520 --> 0:09:14.040 zoom in further and further for you. And there it 0:09:14.120 --> 0:09:16.640 looks like they're just on a perfect collision course and 0:09:16.679 --> 0:09:19.480 then they just miss at the last second. Now, what 0:09:19.480 --> 0:09:22.080 what does that miss look like on distances that are 0:09:22.120 --> 0:09:25.319 appreciable to us. The answer is it came within about 0:09:25.480 --> 0:09:29.320 seventy three thousand kilometers or about forty five thousand miles 0:09:29.320 --> 0:09:31.920 of Earth. So that sounds pretty far away, right, that's 0:09:31.960 --> 0:09:35.120 at least few trips to Disneyland. But if you stay 0:09:35.200 --> 0:09:37.439 zoomed out, like we were just talking about, looking at 0:09:37.640 --> 0:09:40.040 looking at this path on like an Earth orbit scale, 0:09:40.080 --> 0:09:43.040 the distance is something you can't even really see. It 0:09:43.160 --> 0:09:47.079 passed inside the orbit of the Moon, and that's pretty close. 0:09:47.440 --> 0:09:49.800 Like it is. Essentially you could you could say it 0:09:49.840 --> 0:09:54.160 has passed within the realm of U, within the sphere 0:09:54.320 --> 0:09:57.439 of of human culture, you know, like we have been 0:09:57.480 --> 0:10:00.000 to the Moon and this thing has traversed the space 0:10:00.400 --> 0:10:02.720 betwixt the two. Yeah, and it wasn't even in the 0:10:02.760 --> 0:10:06.800 far side of the Moon circumference like in fact, twenty 0:10:06.920 --> 0:10:10.080 nineteen okay, came within less than twenty percent of the 0:10:10.120 --> 0:10:13.080 distance from the Earth to the Moon. It was pretty close. 0:10:13.440 --> 0:10:15.319 According to a to a piece I was reading on 0:10:15.440 --> 0:10:19.720 vox by Kelsey Piper, on average, about zero point five 0:10:19.800 --> 0:10:22.839 percent of asteroids that come within this range of Earth 0:10:23.200 --> 0:10:26.520 actually hit us. So that's that's a nice thing to consider, right. 0:10:26.559 --> 0:10:29.160 That's on the other hand, the other ninety nine point 0:10:29.240 --> 0:10:32.480 five percent within this range still pass us by, like 0:10:33.000 --> 0:10:36.080 nineteen okay, did you know the vast majority are not 0:10:36.120 --> 0:10:38.280 going to hit Earth? So that's good, right, But we 0:10:38.480 --> 0:10:42.120 kind of must ask the question, what if an asteroid 0:10:42.200 --> 0:10:46.280 of this size did hit Earth? What exactly would happen? Uh? 0:10:46.400 --> 0:10:49.040 So I was reading an article by Liam Mannox of 0:10:49.120 --> 0:10:53.079 the Sydney Morning Herald who interviewed the Swinburne University astronomer 0:10:53.160 --> 0:10:56.320 Dr Alan Duffy, and Duffy said that an object of 0:10:56.360 --> 0:11:00.559 this size would be what astronomers sometimes maybe maybe loqually 0:11:01.040 --> 0:11:04.440 call a city killer. So it's not of a size 0:11:04.480 --> 0:11:07.679 that would cause a mass extinction or potentially qualify as 0:11:07.720 --> 0:11:11.000 like a planet killer. Its worst effects would probably be 0:11:11.160 --> 0:11:14.719 local in the area around where it hit, and if 0:11:14.720 --> 0:11:18.600 it had struck Earth. Duffy compared this hypothetical impact to 0:11:18.800 --> 0:11:22.679 something like a large nuclear weapons strike. One of our 0:11:23.200 --> 0:11:27.320 listeners on the Facebook discussion module that Stuff to Build 0:11:27.320 --> 0:11:30.480 Your Mind discussion module Facebook group shared a like a 0:11:30.520 --> 0:11:34.160 map tool where you can input your city and then 0:11:34.280 --> 0:11:38.520 look at what would happen if various models of nuclear 0:11:38.559 --> 0:11:41.679 weaponry hit your city and determine like how far the 0:11:41.760 --> 0:11:44.880 danger the danger zone is, how you know, far the 0:11:44.880 --> 0:11:48.679 the radiation radiation extends. It's a scary tool, yeah, but 0:11:49.160 --> 0:11:51.520 it also just really drives home that most of these 0:11:51.720 --> 0:11:57.160 these devices are very capable of destroying modern cities, or 0:11:57.200 --> 0:12:00.840 at least taking such a sizeable and crucial chunk out 0:12:00.840 --> 0:12:05.199 of them to effectively destroy it. And I mean so 0:12:05.600 --> 0:12:09.120 this impact would have actually been bigger than the real 0:12:09.280 --> 0:12:12.040 atomic weapons that we have seen deployed on cities in 0:12:12.360 --> 0:12:16.079 human history. According to Duffy, this impact, if it had 0:12:16.160 --> 0:12:19.440 hit Earth, would have hit with over quote thirty times 0:12:19.480 --> 0:12:23.280 the energy of the atomic blast at Hiroshima. And so 0:12:23.320 --> 0:12:25.839 that you might be wondering, Okay, if you don't usually 0:12:25.840 --> 0:12:28.000 think about these things, how would it have that much energy? 0:12:28.000 --> 0:12:30.320 It's not a bomb, right, It's just a rock. Why 0:12:30.320 --> 0:12:34.720 would it act like a bomb that explodes? Um. So 0:12:34.920 --> 0:12:37.000 what you have to remember is that the the energy 0:12:37.200 --> 0:12:40.840 released upon an impact with Earth's surface is a product 0:12:40.920 --> 0:12:44.199 of the mass and velocity of the falling object. Now, normally, 0:12:44.240 --> 0:12:47.199 when objects like a chunk of rock fall to the ground, 0:12:47.200 --> 0:12:50.440 they don't behave like a bomb because they're relatively light 0:12:50.600 --> 0:12:54.319 and they're relatively slow. So this, this asteroid, would be 0:12:54.360 --> 0:12:57.120 a falling object of a size and a speed that 0:12:57.200 --> 0:13:01.320 we never encounter in normal life in Earth's atmosphere. Something 0:13:01.559 --> 0:13:04.000 you know, maybe a hundred meters across, like a giant 0:13:04.080 --> 0:13:06.800 boulder or a chunk of a mountainside. Things that big 0:13:06.840 --> 0:13:09.440 don't usually fall to begin with, I mean, except maybe 0:13:09.520 --> 0:13:12.800 like huge airplanes. Uh. And then it would be traveling 0:13:12.800 --> 0:13:16.120 at twenty four kilometers per second, which is more than 0:13:16.160 --> 0:13:20.240 twenty times the speed of your average shooting bullet. Yeah, exactly. 0:13:20.280 --> 0:13:22.960 And so once you multiply those things together, that mass 0:13:23.000 --> 0:13:25.760 and that velocity, and it also matters, of course the 0:13:25.800 --> 0:13:28.880 angle at which it enters the atmosphere hits the ground. 0:13:29.240 --> 0:13:32.240 But once you build up these levels of kinetic energy, 0:13:32.400 --> 0:13:35.760 any normal falling object like a huge chunk of rock 0:13:35.880 --> 0:13:38.240 or metal as you would find in the case of 0:13:38.240 --> 0:13:41.840 an asteroid, essentially becomes a bomb upon impact. And this 0:13:41.880 --> 0:13:43.520 is a fact we've touched on in some of our 0:13:43.559 --> 0:13:47.200 more science fiction ety episodes where we've talked about about 0:13:47.240 --> 0:13:51.360 how if you simply had orbital superiority over a planet, 0:13:51.360 --> 0:13:55.280 this planet or another planet that had occupants, just by 0:13:55.400 --> 0:13:59.800 virtue of having orbit, uh an orbital position, you could 0:13:59.840 --> 0:14:02.319 drop anything. You would not need to drop a bomb 0:14:02.559 --> 0:14:05.480 from that height. If you could drop just a big 0:14:05.520 --> 0:14:08.640 piece of metal or rock, et cetera, then you already 0:14:08.679 --> 0:14:11.480 you have a tremendous weapon at your disposal. And this 0:14:11.520 --> 0:14:14.439 is where we get the you know, the term rods 0:14:14.559 --> 0:14:19.320 from god kinetic energy kannetic kinetic energy weapons would just 0:14:19.360 --> 0:14:21.160 be a matter of just drop anything from up there 0:14:21.200 --> 0:14:24.560 and it can destroy like nothing else. Yeah, it's scary. 0:14:24.640 --> 0:14:26.800 And now, on the other hand, uh, we want to 0:14:26.800 --> 0:14:29.720 remember throughout this episode to not be alarmist and not 0:14:29.760 --> 0:14:32.880 get people to worked up. Now, first of all, this asteroid, 0:14:32.920 --> 0:14:35.400 like we said, it already missed us. It's on its way. 0:14:35.440 --> 0:14:39.240 About things like this in general, it really does matter 0:14:39.360 --> 0:14:43.960 where it hits. So fortunately in this scenario, the majority 0:14:44.080 --> 0:14:46.960 of Earth's humans are actually squeezed into a fairly small 0:14:47.000 --> 0:14:50.360 subsection of Earth's surface, So chances are that even if 0:14:50.680 --> 0:14:53.080 an asteroid like this were to hit Earth, it would 0:14:53.080 --> 0:14:55.280 probably strike in the ocean. Now that could have negative 0:14:55.320 --> 0:14:58.760 consequences depending on where it happens, but but definitely better 0:14:58.760 --> 0:15:02.520 than a hitting u like you know, land, yeah, populated 0:15:02.560 --> 0:15:06.000 area especially yeah uh. And if it did strike on land, 0:15:06.080 --> 0:15:09.640 it would probably most likely hit in a rural, less 0:15:09.680 --> 0:15:12.640 populated area. Now, not like that would be okay, but 0:15:12.720 --> 0:15:15.240 that would be you know, obviously fewer casualties than it 0:15:15.360 --> 0:15:18.240 hitting one of these smaller subsections of Earth's surface where 0:15:18.240 --> 0:15:21.520 there are a lot of people. Now, small objects from 0:15:21.520 --> 0:15:24.840 space passed by Earth and inter Earth's atmosphere all the time. 0:15:25.080 --> 0:15:28.560 What's interesting about this asteroid was the combination of its 0:15:28.600 --> 0:15:32.600 size and how close it passed. Apparently a few dozen 0:15:32.720 --> 0:15:36.560 smaller objects like less than twelve meters in diameter passed 0:15:36.640 --> 0:15:39.680 within the orbit of the Moon every year, and according 0:15:39.720 --> 0:15:42.680 to one article I was reading, objects of about the 0:15:42.760 --> 0:15:46.320 size of twenty nineteen okay, only passed by this close 0:15:46.360 --> 0:15:49.400 to Earth roughly once every ten years. So we just 0:15:49.480 --> 0:15:52.880 had like a decade event and that's generally our way 0:15:52.880 --> 0:15:57.320 of understanding these these these asteroids we generally talk about 0:15:57.320 --> 0:15:59.720 like the frequency of their occurrence. Is this a once 0:15:59.720 --> 0:16:02.000 in a decade, Is this a once in a lifetime? 0:16:02.160 --> 0:16:05.160 Is this, you know, once in a thousand years or more? 0:16:05.440 --> 0:16:07.840 That's right, because all these things we think of across 0:16:07.920 --> 0:16:10.680 time scales in in terms of probability. Right, you know, 0:16:11.520 --> 0:16:15.160 things that are unlikely to happen any given year become 0:16:15.280 --> 0:16:18.880 near certainties at a certain time scale. Right. And of course, 0:16:18.920 --> 0:16:22.480 these devastating impacts of you know, of of you know, 0:16:22.480 --> 0:16:25.320 from prehistoric times and uh, you know, they tend to 0:16:25.400 --> 0:16:27.760 leave of mark. You can tell that they occurred, and 0:16:27.800 --> 0:16:31.640 we can extrapolate the kind of damage that that resonated 0:16:31.920 --> 0:16:34.720 exactly right. So to come back to another thing we 0:16:34.720 --> 0:16:38.240 we mentioned earlier, we mentioned that this thing snuck up, right, 0:16:38.400 --> 0:16:41.480 we seemed to come out of nowhere. People astronomers did 0:16:41.520 --> 0:16:45.240 not detect it until just days before its arrival. And 0:16:45.280 --> 0:16:47.720 that's ultimately the most sobering thing about it. Is not 0:16:47.840 --> 0:16:51.280 that that that asteroids like this exists, or that they 0:16:51.320 --> 0:16:54.200 that they they reached these sizes or or passed in 0:16:54.240 --> 0:16:56.880 this proximity, but that we just didn't see it coming, 0:16:56.920 --> 0:16:59.200 and then it was gone like that, just passed us 0:16:59.320 --> 0:17:01.800 in the night. Then we realized how close we came. 0:17:02.280 --> 0:17:05.320 So the question is why. There are a couple of 0:17:05.320 --> 0:17:09.760 reasons here. One is that it was relatively small and faint. Obviously, 0:17:10.240 --> 0:17:12.560 it's easier to use our telescopes to pick up and 0:17:12.600 --> 0:17:16.360 track near Earth objects that are larger and reflect more light. 0:17:16.640 --> 0:17:19.920 Another reason is that it came generally from the direction 0:17:19.960 --> 0:17:22.520 of the Sun, which makes it harder to see because 0:17:22.520 --> 0:17:25.760 of the glare in the background. Another reason it was 0:17:25.800 --> 0:17:28.280 hard to pick up was that it was traveling very fast. 0:17:28.359 --> 0:17:31.959 It makes it harder to detect. Other asteroids recently passing 0:17:32.000 --> 0:17:34.240 by Earth have been slower. According to an article I 0:17:34.280 --> 0:17:37.639 was reading by Alison Chew in the Washington Post, most 0:17:37.680 --> 0:17:40.800 of the recent asteroids passing by Earth have been between 0:17:40.840 --> 0:17:44.400 four and nineteen kilometers per second. Remember again, this one 0:17:44.520 --> 0:17:47.399 was booking at twenty four kilometers per second, which is 0:17:47.520 --> 0:17:50.159 very fast, which also, of course, potentially means that if 0:17:50.160 --> 0:17:52.280 it had hit Earth, the impact would have been more 0:17:52.320 --> 0:17:55.680 powerful because it's going faster. Next, the shape of its 0:17:55.800 --> 0:17:59.040 orbit made it difficult to detect. Nineteen Okay had a 0:17:59.119 --> 0:18:02.679 very elliptical orbit, meaning it was not roughly circular like 0:18:02.720 --> 0:18:04.200 a lot of the orbit of a lot of things, 0:18:04.200 --> 0:18:07.399 most of the planets, it had an oblong oval shape. 0:18:07.440 --> 0:18:10.360 So this asteroid, as it travels around the Sun, sometimes 0:18:10.359 --> 0:18:13.040 it comes very close, like within the orbit of Venus, 0:18:13.280 --> 0:18:15.760 and other times it gets very far away, out beyond 0:18:15.840 --> 0:18:18.560 the orbit of Mars. This also made it more difficult 0:18:18.560 --> 0:18:20.880 to detect. And so if you add all this up, 0:18:20.920 --> 0:18:24.439 you've got this small, fast moving object that's relatively faint 0:18:24.680 --> 0:18:27.720 out there orbiting the Sun, and then suddenly, within maybe 0:18:27.720 --> 0:18:30.159 just a couple of weeks before it passes us, it 0:18:30.200 --> 0:18:33.199 becomes bright enough to see, and then other people have 0:18:33.280 --> 0:18:35.480 to see it and confirm it. Uh, somebody's got to 0:18:35.520 --> 0:18:37.240 be looking at the right place at the right time 0:18:37.280 --> 0:18:40.040 in the first place to see it. It's not easy. 0:18:40.160 --> 0:18:42.640 Things like this really can just sneak up on us, 0:18:42.680 --> 0:18:46.600 and scientists don't necessarily always have fore warning. So this 0:18:46.720 --> 0:18:49.480 kind of serves as a reminder that our orbital neighborhood 0:18:50.080 --> 0:18:52.560 is not a void. Space is not just avoid is 0:18:52.600 --> 0:18:56.040 full of rocks and comets and stuff, and that while 0:18:56.160 --> 0:18:59.920 our astronomers do a really admirable job cataloging near Earth 0:19:00.040 --> 0:19:03.359 objects with the tools available to them. Objects of really 0:19:03.400 --> 0:19:06.159 frightening size can still creep up on us in ways 0:19:06.200 --> 0:19:08.840 that give us only days or even hours of warning, 0:19:09.240 --> 0:19:11.679 or maybe no warning at all. Speaking to the Sydney 0:19:11.720 --> 0:19:16.800 Morning Herald, Australian National University astronomer Dr Brad Tucker said 0:19:16.840 --> 0:19:20.080 that it is completely possible that objects of comparable size, 0:19:20.119 --> 0:19:23.280 objects about the size of twenty nineteen okay, passed by 0:19:23.400 --> 0:19:25.560 us like this and we never detect them at all. 0:19:25.880 --> 0:19:28.440 Sometimes they just go right by and no, no human 0:19:28.520 --> 0:19:30.760 is any the wiser. All right, well, and that's sobering. Note. 0:19:30.800 --> 0:19:32.159 We're going to take a quick break, but when we 0:19:32.240 --> 0:19:35.439 come back, we will discuss what an asteroid of this 0:19:35.560 --> 0:19:41.840 size would do if it actually hit us. Thank alright, 0:19:41.840 --> 0:19:43.760 we're back, all right. So we're talking about the idea 0:19:43.840 --> 0:19:47.400 of the asteroid that just recently passed the Earth within 0:19:47.440 --> 0:19:51.360 the past few weeks nineteen okay, which again zero risk 0:19:51.440 --> 0:19:54.800 to us now it's gone, you know, But we're thinking 0:19:54.800 --> 0:19:58.000 about what an asteroid of this size, you know, roughly 0:19:58.119 --> 0:20:01.600 this size would do if were to be you know, 0:20:01.680 --> 0:20:04.840 the zero point five percent of asteroids that come within 0:20:04.880 --> 0:20:08.080 this range that actually do hit Earth. Uh, we know 0:20:08.240 --> 0:20:10.720 that an impact from a large enough asteroid can be 0:20:10.880 --> 0:20:15.880 devastating on a planetary scale, like space impacts have contributed 0:20:15.920 --> 0:20:18.439 to mass extinctions in Earth history, and of course we 0:20:18.480 --> 0:20:22.760 know that the main theory explaining the the kt extinction 0:20:22.840 --> 0:20:26.840 or the KPg extinction was a theory involving a space impact, 0:20:26.840 --> 0:20:29.240 and of course that this was the extinction event that 0:20:29.400 --> 0:20:32.480 killed the dinosaurs about sixty six million years ago. It's 0:20:32.520 --> 0:20:36.560 the third greatest extinction event in Earth history. The basic 0:20:36.640 --> 0:20:38.879 details are probably familiar to you at this point, but 0:20:39.119 --> 0:20:43.119 a commeter asteroid some bulllied from space hit the Earth 0:20:43.480 --> 0:20:47.400 in what is now the Yucatan Peninsula was probably I've 0:20:47.440 --> 0:20:49.879 seen estimates, uh. I think maybe the older estimates are 0:20:49.960 --> 0:20:52.960 that it was ten to fifteen kilometers in diameter. More recently, 0:20:53.000 --> 0:20:55.880 I think I've seen people saying sixteen kilometers in diameter 0:20:56.200 --> 0:20:58.480 is a huge object, you know, measured on a scale 0:20:58.480 --> 0:21:02.200 of miles or kilometers, And an object of this size 0:21:02.240 --> 0:21:06.000 impacting Earth at orbital speed is not just a collision. 0:21:06.080 --> 0:21:08.480 It is, as we were talking about earlier, a detonation. 0:21:08.760 --> 0:21:12.399 It releases a blast of energy equivalent to millions of 0:21:12.480 --> 0:21:16.960 nuclear warheads all exploding at the same time, and things 0:21:16.960 --> 0:21:20.359 on this scale hitting the Earth are especially scary because 0:21:20.400 --> 0:21:24.800 they're not just threatening to organisms living in the local 0:21:24.960 --> 0:21:28.439 area right that they can have planet scale effects, like 0:21:28.520 --> 0:21:32.119 the leading theory about the cause of the KPg extinction 0:21:32.640 --> 0:21:35.760 is that this impact happened. This bowled from space hit 0:21:35.800 --> 0:21:38.560 the Earth, and it threw up so much dust and 0:21:38.640 --> 0:21:41.920 debris into the atmosphere that it blocked out the sun 0:21:42.080 --> 0:21:46.199 for perhaps months, preventing photosynthesis, killing off huge numbers of 0:21:46.200 --> 0:21:50.000 plants and photosynthesizing organisms, which of course cut off food 0:21:50.040 --> 0:21:53.679 sources for larger animals. And more than three quarters of 0:21:53.760 --> 0:21:56.880