Asteroid 2019 OK: The Little Doomsday

The near-Earth object (NEO) known as Asteroid 2019 OK just made an unexpected close pass, raising the hair on the back of humanity’s collective neck. In this episode of Stuff to Blow Your Mind, Robert and Joe weigh the risks posed by other NEOs and discuss what we’re doing to track them and even stop an incoming doomsday rock. 

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:03):
Welcome Stuff to Blow Your Mind, a production of I
Heart Radios How Stuff Works. Hey, you welcome to Stuff
to Blow your Mind. My name is Robert Lamb and
I'm Joe McCormick. You know, we've been talking a lot
recently about you know, some perhaps more ambiguous risks to humanity,

(00:25):
but but not so much the ambiguity in this episode. Wait,
what are the ambiguous risks? Oh, you know we're talking
about like you know, you're getting talking about like social
media and how and how it's affecting the human condition
or you know, certainly in our episodes on psychedelics, you know,
we talked about some of the more ambiguous and even
more concrete threats facing humanity and to what extent some

(00:48):
commentators think that the psychedelic experience can prepare us for
those threats. Okay, so kind of vague possible psychic and
cultural threats, right, yeah, less less threats like a huge
rock hitting you. Right, because because we over good, what
we're gonna be talking about the day is certainly the
kind of threat that that a mushroom is not going
to be able to help us with. Right, So we

(01:10):
wanted to talk about an interesting, perhaps hair raising story
from recent Space News. So, just within the past couple
of weeks, Earth had a very close encounter and almost
perfectly timed intersection with the orbit of a fast moving
object from outer space. And the creepy and fascinating thing

(01:31):
about this is that this object came very close to
Earth and we had almost no forewarning that it was coming.
So what was this thing? Well, I actually first saw
it when Robert shared an article about it on on
social media. That's right, Yeah, there we go, determining the
topics of all conversation. Well, and the crazy thing about
it is that, you know, as we've discussed in the show,

(01:52):
and the the more extreme things get to know, the rise
to the surface and social media and especially right now,
it tends to be stuff related to politics. But then somehow, uh,
this one story breached the surface. It may have helped
that it had the word killer in the headline. So
this was an asteroid that is now officially called asteroid nineteen. Okay,

(02:14):
and that doesn't mean it's okay, that's just a you know,
that's the code assigned to it. I read it as
asteroid two thousand, nineteen, Okay, it's kind of like that.
So it was detected by astronomers in Brazil and the
United States before being confirmed by NASA JPL and on July.

(02:35):
It passed by Earth at a speed of about twenty
four kilometers per second, which is like fifty four thousand
miles per hour. Pretty fast. And what we want to
emphasize is it's already gone, okay, so we should emphasize
that at the beginning, this asteroid represents zero threat to
us on any meaningful time scale. It is passed, it's

(02:57):
on its way to other things. And the reason we're
talking about this is that I feel like this event
is instructive. It shows the real life and death importance
of astronomy in general and improving our capabilities for cataloging
near Earth objects more specifically. And it's also I think
an event that really reveals the part of you that

(03:17):
either leans towards the positive or the negative interpretation of things,
you know, the glass half full half empty kind of thing, right,
the near miss versus near hit. Yeah, and also reminded
of the old adage. You know, I don't know if
it's truly an adage, but the observation that you never
hear the one that has your name on it. You know,
generally talking about say, you know, a bullet in a military,

(03:37):
uh situation. It's like on the Sopranos, you know, you
never know the one that's coming for you, right. But
the thing is we are we are in the business
right now of trying to know the ones that have
our name on it, the the asteroids particularly that have
that that have Earth or possibly Earth printed on their side. Yeah,
and it's always going to be a probabilistic thing when

(03:59):
we're looking to far out, so you wouldn't know for sure,
but you'd say, you know, we think there's a you know,
zero point whatever percent chance this has Earth on its name,
has Earth's name on it, or maybe has a chance
right yet to be clear. And we'll get into some
of the statistics here in a bit. But there there
are no asteroids out there right now that that Nassa

(04:20):
or anyone else is saying this is a definite collision course.
No no big ones, No big ones. So yeah, I mean,
obviously they are ones that are going to imbact Us
and with with with a little or no effect. But
in terms of like really big problematic asteroids, the ones
that are the ones that we know of, and it
is a you know, just a segment of the ones
that are out there. There are none that we are

(04:41):
like positive like, this is the one. This is the
one we have to act on right now, right now. Yeah,
but this twenty nineteen, Okay, asteroids. So first of all,
the question we need to play the glass half full
half empty thing with Was it big or was it small? Well,
it was between we think about fifty seven and a
hundred and thirty meters in diameter, which is a hundred
and eighty seven to four hundred and twenty seven feet.

(05:05):
Is that big or is that small? Well, it depends
on what you compare it to the object that struck
the Earth sixty six million years ago, the impact that
most likely played a major role in the extinction of
the dinosaurs. That one was probably I've seen estimates of
ten to fifteen kilometers across. I've seen that people say
more recently, this might be an updated or more more
precise figure that it was like fifteen or sixteen kilometers across.

(05:28):
That's obviously a lot bigger. We're we're talking this object
that just went past us is a couple of orders
of magnitude smaller than that. So we're not talking about
like necessarily a full blown civilization buster. No no, no
extinction event level impact. Yeah. Unfortunately, astronomers believe that more
than nine percent of objects in this extinction event size

(05:48):
category category, the category of things on the scale of
the asteroid that killed the dinosaurs, uh, things like that,
more than nine percent in our orbital vicinity have already
been disc covered and cataloged by NASA and other observers
and space agencies because the bare ones are simply easier
to spot, right exactly, And so for the biggest of
the biggest, we're pretty sure we know where they are,

(06:11):
uh that, and that we would be able to predict
if they're headed our way, which is good, right, But
then again, you could compare it to something on the
other side. So the Chelly bents Comedia, which exploded in
the atmosphere over Russia in was only about twenty meters
in diameter, just twenty And this meteor was not even
large enough to reach the ground. It didn't hit the

(06:32):
surface of the Earth like most smaller objects entering our
atmosphere from space. It exploded in the atmosphere and what's
known as an air burst. And this this explosion injured
over a thousand people. I think it was close to people.
It damaged buildings, it collapsed roofs, it smashed windows in
this big elliptical impact zone stretched out for dozens of

(06:53):
kilometers um and and a lot of the damage and
human injuries from this air blast were due to like
blown out glass from windows hitting people. I should say.
The footage also, of course, was incredible and certainly certainly
makes you feel like a primate when you watch it.
You feel like an earth bound primate um that has
no control over the great fiery mass that is just

(07:16):
seared across the horizon. It's a it's a two thousand
one of space Odyssey monolith kind of thing. Yeah, you're like, well, okay,
should I worship that? Maybe? But so that one, the
one that caused all that damage, was just twenty wide.
This this one that just passed us was somewhere between
fifty seven and a hundred and thirty meters. Why that's

(07:36):
a good bit bigger. It's somewhere between an extinction event
level asteroid or object and you know, one of the
smaller ones like we've seen with Cheli Bensk. In fact,
the size of this thing that just passed us is
probably roughly comparable to the size of something we're gonna
talk about more in a bit, the meteor that exploded
over Siberia in nineteen o eight and the event known

(07:58):
as the Tunguska in impact. And like I said, well,
we'll come back to that later. But basically though, the
issue is it depends on where it hits. Y. Yeah,
the thing that just passed us. The point is that
it poses no threat to us. It's already gone. But
if it had hit Earth, that would be really scary

(08:19):
on the off chance that it came anywhere near a
populated area. And of course the location is important with
any of these. I mean, I've I've read arguments that
the chicks a lube impact, Like if it had hit uh,
if it had been a water impact as opposed to
a land impact, Um, you know, it would have made
some difference in what occurred. So that's that's going to

(08:41):
be a factor no matter what scale you're talking about here. Absolutely, yeah,
that that place a big role. Well, we'll talk more
about that as we go on. So uh So we
talked about the size, Another question is how close exactly
did it come to Earth? Because there are the simulations
that you can watch online. You should look this up. Actually,
that show like the orbital pathways of Earth and this

(09:02):
asteroid and as they sort of approach each other, as
the intersection of these two orbital pathways comes up, it'll
zoom in further and further for you. And there it
looks like they're just on a perfect collision course and
then they just miss at the last second. Now, what
what does that miss look like on distances that are
appreciable to us. The answer is it came within about

(09:25):
seventy three thousand kilometers or about forty five thousand miles
of Earth. So that sounds pretty far away, right, that's
at least few trips to Disneyland. But if you stay
zoomed out, like we were just talking about, looking at
looking at this path on like an Earth orbit scale,
the distance is something you can't even really see. It
passed inside the orbit of the Moon, and that's pretty close.

(09:47):
Like it is. Essentially you could you could say it
has passed within the realm of U, within the sphere
of of human culture, you know, like we have been
to the Moon and this thing has traversed the space
betwixt the two. Yeah, and it wasn't even in the
far side of the Moon circumference like in fact, twenty
nineteen okay, came within less than twenty percent of the

(10:10):
distance from the Earth to the Moon. It was pretty close.
According to a to a piece I was reading on
vox by Kelsey Piper, on average, about zero point five
percent of asteroids that come within this range of Earth
actually hit us. So that's that's a nice thing to consider, right.
That's on the other hand, the other ninety nine point
five percent within this range still pass us by, like

(10:33):
nineteen okay, did you know the vast majority are not
going to hit Earth? So that's good, right, But we
kind of must ask the question, what if an asteroid
of this size did hit Earth? What exactly would happen? Uh?
So I was reading an article by Liam Mannox of
the Sydney Morning Herald who interviewed the Swinburne University astronomer

(10:53):
Dr Alan Duffy, and Duffy said that an object of
this size would be what astronomers sometimes maybe maybe loqually
call a city killer. So it's not of a size
that would cause a mass extinction or potentially qualify as
like a planet killer. Its worst effects would probably be
local in the area around where it hit, and if

(11:14):
it had struck Earth. Duffy compared this hypothetical impact to
something like a large nuclear weapons strike. One of our
listeners on the Facebook discussion module that Stuff to Build
Your Mind discussion module Facebook group shared a like a
map tool where you can input your city and then
look at what would happen if various models of nuclear

(11:38):
weaponry hit your city and determine like how far the
danger the danger zone is, how you know, far the
the radiation radiation extends. It's a scary tool, yeah, but
it also just really drives home that most of these
these devices are very capable of destroying modern cities, or
at least taking such a sizeable and crucial chunk out

(12:00):
of them to effectively destroy it. And I mean so
this impact would have actually been bigger than the real
atomic weapons that we have seen deployed on cities in
human history. According to Duffy, this impact, if it had
hit Earth, would have hit with over quote thirty times
the energy of the atomic blast at Hiroshima. And so

(12:23):
that you might be wondering, Okay, if you don't usually
think about these things, how would it have that much energy?
It's not a bomb, right, It's just a rock. Why
would it act like a bomb that explodes? Um. So
what you have to remember is that the the energy
released upon an impact with Earth's surface is a product
of the mass and velocity of the falling object. Now, normally,

(12:44):
when objects like a chunk of rock fall to the ground,
they don't behave like a bomb because they're relatively light
and they're relatively slow. So this, this asteroid, would be
a falling object of a size and a speed that
we never encounter in normal life in Earth's atmosphere. Something
you know, maybe a hundred meters across, like a giant
boulder or a chunk of a mountainside. Things that big

(13:06):
don't usually fall to begin with, I mean, except maybe
like huge airplanes. Uh. And then it would be traveling
at twenty four kilometers per second, which is more than
twenty times the speed of your average shooting bullet. Yeah, exactly.
And so once you multiply those things together, that mass
and that velocity, and it also matters, of course the
angle at which it enters the atmosphere hits the ground.

(13:29):
But once you build up these levels of kinetic energy,
any normal falling object like a huge chunk of rock
or metal as you would find in the case of
an asteroid, essentially becomes a bomb upon impact. And this
is a fact we've touched on in some of our
more science fiction ety episodes where we've talked about about
how if you simply had orbital superiority over a planet,

(13:51):
this planet or another planet that had occupants, just by
virtue of having orbit, uh an orbital position, you could
drop anything. You would not need to drop a bomb
from that height. If you could drop just a big
piece of metal or rock, et cetera, then you already
you have a tremendous weapon at your disposal. And this

(14:11):
is where we get the you know, the term rods
from god kinetic energy kannetic kinetic energy weapons would just
be a matter of just drop anything from up there
and it can destroy like nothing else. Yeah, it's scary.
And now, on the other hand, uh, we want to
remember throughout this episode to not be alarmist and not
get people to worked up. Now, first of all, this asteroid,

(14:32):
like we said, it already missed us. It's on its way.
About things like this in general, it really does matter
where it hits. So fortunately in this scenario, the majority
of Earth's humans are actually squeezed into a fairly small
subsection of Earth's surface, So chances are that even if
an asteroid like this were to hit Earth, it would

(14:53):
probably strike in the ocean. Now that could have negative
consequences depending on where it happens, but but definitely better
than a hitting u like you know, land, yeah, populated
area especially yeah uh. And if it did strike on land,
it would probably most likely hit in a rural, less
populated area. Now, not like that would be okay, but
that would be you know, obviously fewer casualties than it

(15:15):
hitting one of these smaller subsections of Earth's surface where
there are a lot of people. Now, small objects from
space passed by Earth and inter Earth's atmosphere all the time.
What's interesting about this asteroid was the combination of its
size and how close it passed. Apparently a few dozen
smaller objects like less than twelve meters in diameter passed

(15:36):
within the orbit of the Moon every year, and according
to one article I was reading, objects of about the
size of twenty nineteen okay, only passed by this close
to Earth roughly once every ten years. So we just
had like a decade event and that's generally our way
of understanding these these these asteroids we generally talk about

(15:57):
like the frequency of their occurrence. Is this a once
in a decade, Is this a once in a lifetime?
Is this, you know, once in a thousand years or more?
That's right, because all these things we think of across
time scales in in terms of probability. Right, you know,
things that are unlikely to happen any given year become
near certainties at a certain time scale. Right. And of course,

(16:18):
these devastating impacts of you know, of of you know,
from prehistoric times and uh, you know, they tend to
leave of mark. You can tell that they occurred, and
we can extrapolate the kind of damage that that resonated
exactly right. So to come back to another thing we
we mentioned earlier, we mentioned that this thing snuck up, right,
we seemed to come out of nowhere. People astronomers did

(16:41):
not detect it until just days before its arrival. And
that's ultimately the most sobering thing about it. Is not
that that that asteroids like this exists, or that they
that they they reached these sizes or or passed in
this proximity, but that we just didn't see it coming,
and then it was gone like that, just passed us
in the night. Then we realized how close we came.

(17:02):
So the question is why. There are a couple of
reasons here. One is that it was relatively small and faint. Obviously,
it's easier to use our telescopes to pick up and
track near Earth objects that are larger and reflect more light.
Another reason is that it came generally from the direction
of the Sun, which makes it harder to see because

(17:22):
of the glare in the background. Another reason it was
hard to pick up was that it was traveling very fast.
It makes it harder to detect. Other asteroids recently passing
by Earth have been slower. According to an article I
was reading by Alison Chew in the Washington Post, most
of the recent asteroids passing by Earth have been between
four and nineteen kilometers per second. Remember again, this one

(17:44):
was booking at twenty four kilometers per second, which is
very fast, which also, of course, potentially means that if
it had hit Earth, the impact would have been more
powerful because it's going faster. Next, the shape of its
orbit made it difficult to detect. Nineteen Okay had a
very elliptical orbit, meaning it was not roughly circular like
a lot of the orbit of a lot of things,
most of the planets, it had an oblong oval shape.

(18:07):
So this asteroid, as it travels around the Sun, sometimes
it comes very close, like within the orbit of Venus,
and other times it gets very far away, out beyond
the orbit of Mars. This also made it more difficult
to detect. And so if you add all this up,
you've got this small, fast moving object that's relatively faint
out there orbiting the Sun, and then suddenly, within maybe

(18:27):
just a couple of weeks before it passes us, it
becomes bright enough to see, and then other people have
to see it and confirm it. Uh, somebody's got to
be looking at the right place at the right time
in the first place to see it. It's not easy.
Things like this really can just sneak up on us,
and scientists don't necessarily always have fore warning. So this
kind of serves as a reminder that our orbital neighborhood

(18:50):
is not a void. Space is not just avoid is
full of rocks and comets and stuff, and that while
our astronomers do a really admirable job cataloging near Earth
objects with the tools available to them. Objects of really
frightening size can still creep up on us in ways
that give us only days or even hours of warning,
or maybe no warning at all. Speaking to the Sydney

(19:11):
Morning Herald, Australian National University astronomer Dr Brad Tucker said
that it is completely possible that objects of comparable size,
objects about the size of twenty nineteen okay, passed by
us like this and we never detect them at all.
Sometimes they just go right by and no, no human
is any the wiser. All right, well, and that's sobering. Note.
We're going to take a quick break, but when we

(19:32):
come back, we will discuss what an asteroid of this
size would do if it actually hit us. Thank alright,
we're back, all right. So we're talking about the idea
of the asteroid that just recently passed the Earth within
the past few weeks nineteen okay, which again zero risk
to us now it's gone, you know, But we're thinking

(19:54):
about what an asteroid of this size, you know, roughly
this size would do if were to be you know,
the zero point five percent of asteroids that come within
this range that actually do hit Earth. Uh, we know
that an impact from a large enough asteroid can be
devastating on a planetary scale, like space impacts have contributed

(20:15):
to mass extinctions in Earth history, and of course we
know that the main theory explaining the the kt extinction
or the KPg extinction was a theory involving a space impact,
and of course that this was the extinction event that
killed the dinosaurs about sixty six million years ago. It's
the third greatest extinction event in Earth history. The basic

(20:36):
details are probably familiar to you at this point, but
a commeter asteroid some bulllied from space hit the Earth
in what is now the Yucatan Peninsula was probably I've
seen estimates, uh. I think maybe the older estimates are
that it was ten to fifteen kilometers in diameter. More recently,
I think I've seen people saying sixteen kilometers in diameter
is a huge object, you know, measured on a scale

(20:58):
of miles or kilometers, And an object of this size
impacting Earth at orbital speed is not just a collision.
It is, as we were talking about earlier, a detonation.
It releases a blast of energy equivalent to millions of
nuclear warheads all exploding at the same time, and things
on this scale hitting the Earth are especially scary because

(21:20):
they're not just threatening to organisms living in the local
area right that they can have planet scale effects, like
the leading theory about the cause of the KPg extinction
is that this impact happened. This bowled from space hit
the Earth, and it threw up so much dust and
debris into the atmosphere that it blocked out the sun

(21:42):
for perhaps months, preventing photosynthesis, killing off huge numbers of
plants and photosynthesizing organisms, which of course cut off food
sources for larger animals. And more than three quarters of
Earth species are believed to have been completely wiped out
in this event. But there's good news. Scientists now think
that if there are asteroids of that size on any

(22:03):
kind of likely collision course with Earth, we would very
very likely already know about them. It's not a sure thing,
but we would really probably know because, like I said,
we've we've cataloged more than nine we think of asteroids
that could be of this size in our orbital neighborhood.
And we're always trying to improve our near Earth object
detection and mapping capabilities, And this is an astronomy priority

(22:27):
of species level importance. Keep watching the skies. But objects
on the scale of the one that just passed us.
Remember it's not even close to as big as that one.
But objects on this scale are trickier. They're more difficult
to be sure about because they're smaller. We also have
less confidence in our ability to detect them ahead of time.
So what would happen if an object roughly on the

(22:49):
scale of twenty nineteen okay, were to hit the earth? Well,
it turns out we actually have a pretty close analogy
from twentieth century history, which we alluded to earlier, and
that is the Tongue event. Robert. For my money, this
is one of the most darkly fascinating events of the
last few hundred years. I think, yeah, they're there, you know,

(23:10):
it's one of one of these stories. It's certainly it's
given the fact that it did not decimate a major
center of population, uh makes it something that doesn't feel,
you know, googlesh to to look at. But it's it's
it doesn't have this kind of mysterious quality to it.
It's almost like it's like a warning shot from the gods.
It is also strangely kind of a magnet for cranky theories.

(23:33):
It really attracts, you know, people who want to believe
that like a sudden black hole or a bit of
anti matter appeared and caused it, or that it was
UFOs or some kind of science fiction, you know, like
Tesla experiment or something. I've seen those various conspiracy theories
and whatnot. I'm sorry for repeating them, because those things
are not correct. I mean, we're positive this was a
space impact. So what happened, Well, on the morning of

(23:55):
June thirtie, nineteen oh eight, okay, nineteen o eight, and
checked from space, Probably some kind of asteroid entered Earth's
atmosphere and possibly hit the ground, but more likely exploded
in the air at an altitude of about five to
ten kilometers over an area of eastern Siberia around the
stony Tunguska River. And this is an area of extremely

(24:18):
sparsely populated wilderness. There's not a lot of people, not
a lot of population density out there, and this explosion
is hard for us to imagine. It annihilated roughly two
thousand square kilometers of forest land, leaving trees flattened or
stripped of all branches. The photos that exist of this
damaged area look like a nuclear test. Site. The forest

(24:41):
is just shredded and pancaked, and there actually were Despite
how sparsely populated this area was, there were some contemporaneous
witnesses who were fairly close. And by fairly close, I
mean within dozens of miles. Uh So, I want to
read one contemporaneous account from a witness named S. B. Simonov,
who lived in a place called Vanavara, which was about

(25:04):
sixty kilometers south southeast from the epicenter of the blast side.
Remember this is sixty kilometers away. Here's how his account goes.
I was sitting on the porch of the house at
the trading station of Vena Vara at breakfast time, and
looking towards the north. I had just raised my axe

(25:24):
to hoop a cask, when suddenly, in the north, above
vassili Iliatch own cools Tunguska Road, the sky split in two,
and high above the forest, the whole northern part of
the sky appeared to be covered with fire. At that moment,
I felt great heat, as if my shirt had caught fire.
This heat came from the north side. I wanted to

(25:46):
pull off my shirt and throw it away, but at
that moment there was a bang in the sky, and
a mighty crash was heard. I was thrown onto the
ground about five and a half meters away from the porch,
and for a moment I lost consciousness. My wife ran
out and carried me into the hut. The crash was
followed by noise like stones falling from the sky or

(26:07):
guns firing. The earth trembled, and when I lay on
the ground, I covered my head because I was afraid
stones might hit it. At the moment when the sky opened,
a hot wind, as from a cannon, blew past the
huts from the north. It left its mark on the
ground in the form of little paths. It damaged onion plants.
Later it turned out that many panes in the windows

(26:28):
had been blown out, and the iron hasp in the
door of the barn had been broken. When the fire appeared,
I saw Kosolopov, who was working near the window of
the house, sit down on the ground, seize his head
with both hands, and then run into the hut sixty
kilometers away. And and and this was again this was

(26:49):
like to what extent I mean today, if you saw that,
you would your your mind would instantly turn to nuclear weapons,
you know. But but there were no nuclear but there
was nothing on the human scale that could, uh, they
could explain what he was witnessing. I mean, you're you're
left to, you know, astronomical explanations if you had privy

(27:09):
to them. Otherwise it's just purely supernatural destruction, exactly. Well.
Some I have read reports that some of the native
Siberian peoples of the region of the known as the
Evenki tribes or the Tung people, believed that the Tunguska
impact was the work of a god named Aga Dy
who's the god of thunder and lightning. Though I've also
seen ody described as these believe these creatures that were

(27:31):
like metal birds of thunder and lightning. Yeah. Other witnesses
and generally describe having seen like a blue white streak
in the sky, followed by what appeared to be this
enormous fire consuming the whole sky, and then this gigantic
column of black smoke and loud blasts and crashing noises

(27:53):
booming over the land. The air blast was picked up
by meteorological equipment really far away, like more and six
thousand kilometers away in England, and reportedly in the nights
following the explosion, and I'm not sure this story is true,
but this is just an anecdote repeated through history, may
may or may not be true. Supposedly, and the sky

(28:15):
remained bright over parts of Europe and Asia in the
following nights and uh and according to this anecdote, it
was so bright that you could stand outside at night
and read a newspaper by the light that was still
glowing in the sky. The blast triggered fires that burned
trees tens of kilometers away. Amazingly, despite how destructive this

(28:35):
blast was, I've read the most recent research on it
has found evidence of only three reported human casualties from
the impact. And this is apparently just sheer luck, you know,
because it was out there where very few people live,
in extremely sparse wilderness. If it had struck over Beijing
or London, it would have been much like a city
getting hit with a nuclear weapon and probably would have

(28:57):
killed millions. Yeah, and I mean of it, it it hid
and major center of population even in I mean, it
could have changed the course of history. I mean, it
just it's it's impossible to really, I mean, I'm sure
you can you can sort of like follow individual uh,
you know, life stories and what non prefats There's been
some speculation on this, but I mean it would it

(29:18):
would have changed the course of history. It would have
It would have killed so many people and impacted uh,
you know, places of of of power. It would have
had an impact on on politics. I mean, this is
it's it's it's almost hard to fathom the the different
world we would live in had this thing impacted pretty

(29:38):
much anywhere else. Right. Uh. Now, one thing we do
know is that an object of the size is not Uh.
While it could have had worldwide events, like you're saying,
like cultural impacts that far, it would not have been
like the KPg extinction event size thing because it wouldn't
have like thrown up sediment that completely blocked out the

(30:00):
sun and like cut off photosynthesis. You know, it wouldn't
be that big, right, Like if it hits St. Petersburg,
it would not have wiped out humanity. It would not
have wiped out, you know, all members of the Russian
Empire or anything to to that extent, but it would
have severely it would have it would have killed countless
people in that one city. Yeah, catastrophic local effects and

(30:22):
maybe some maybe some smaller global effects. Um. And so
another question I guess is with strikes like this, these
smaller ones, not like the you know, KPg event level thing,
but with these smaller ones, has anybody studied what actually
happens to nearby humans and other life forms when this
type of impact occurs, Like if a Tungusca size object hits,

(30:46):
what happens to you if you're nearby? I did find yes,
there is at least one study of this uh. It
was published in Geophysical Research Letters in it's by rump
Lewis and Atkinson. Is called Asteroid Impact of X and
their Immediate Hazards for Human populations. And what the authors
did here is they simulated the impacts of more than

(31:07):
fifty thousand asteroid strikes at random locations on the surface
of the Earth to gain insights on the average effects
of human populations who would be nearby and so. Here
were a few of their main findings. One is that
objects are less than maybe like sixty or seventy meters
across tend not to hit the surface of the Earth,

(31:27):
but rather always explode in the atmosphere. And this is
not without risks like remember that all the damage caused
by the Chelabinsk media which exploded in the sky, but
it it tends to generate the air burst only, and
an air bursts can still be powerful and dangerous. The
main theory, of course about the Tunguska event is that
it was an air burst. It's exploded in the atmosphere

(31:48):
and didn't have a chance to hit the ground, even
though it was a good bit bigger. But for most
sizes of asteroids, by far the greatest risk to humans
is from what's known as wind blast. These are waves,
you know, wave of hot compressed air exploding out of
the object. Uh. The second greatest risk after that is
just straight thermal risk heat generated due to the impact,

(32:11):
And then the third greatest risk in general was due
to tsunamis, And the authors actually found that risk to
human life from tsunamis is relatively lower than they expected,
but it increases a lot as the object becomes larger
than like two hundred or two hundred and fifty in diameter,
And their estimates only include objects up to four hundred
meters in diameter, so effects could change dramatically as objects

(32:35):
become bigger and bigger. Now, Robert, I think I think
we should step back after what we've just been talking about.
We should do in lot a reality check. We don't
want to be alarmists, so to reiterate, the odds are
in our favor here, at least on short time scales,
because the vast majority of asteroids of this size don't
come this close to Earth, maybe roughly one every ten years.
By that estimate we talked about earlier, only about zero

(32:58):
point five percent of asteroid it's that pass within this
range will actually hit Earth. And then even if one
does hit Earth, most of the world's surfaces water, though
of course there can be threats from an impact in
water depending on where it happens. And then much of
the land surface of Earth is sparsely populated, so on
short time scales, the odds of a catastrophic impact on

(33:19):
a city or something like that are very very low.
But it's one of those cases where the chance of
a bad outcome on a short time scale may be low,
but the consequences when that off chance does come to
pass are devastating and on. Of course, the the other
side of the coin is that on long enough time scales,
these events go from extremely unlikely to near certainty. Yeah,

(33:42):
one of the things I keep keep asking when I
look at all these stats. It's like, Okay, am I
comfortable with those odds? But then if I'm comfortable with
the odds, am I am I comfortable with the steaks?
You know? Yeah? Totally uh. And it also raises, I
guess a tangentially interesting question, at least to me, which is, like,
how long have a time scale should we be concerned about? Like,

(34:02):
if something is a civilization level threat but it's unlikely
to happen, you know, more than once within the next
ten thousand years, how much of our attention should it get?
Well that's how much should or how much will it?
You know? I mean, well, yeah, those are very I
mean exactly tend to be rather terrible at at weighing

(34:23):
you know, our immediate situation with long term threats to
to to the survival of the human race sort of
the health of the planet. Yeah, you're exactly right about that.
I mean, obviously we're not even appropriately preparing for extremely
likely to near certain climate related problems that are less
than a hundred years away some or even you know,
happening now or decades away. So maybe this question about

(34:44):
longer time scales is moot just given like what our
capabilities are, Like, maybe it doesn't even matter what we
should be doing, because humans just can't make themselves do it.
But I don't want to be resigned or you know,
I don't want to throw in the towel about that
just because we haven't been good at it so far. No,
because we the we have the tremendous ability to correct
these errors. I mean, this has often brought up on

(35:06):
the subject of climate change. Uh you know, well that's
what I was just referring to. Yeah, I mean, but
but specifically with climate change. Like, yes, we've got ourselves
into quite a mess, and that's that's bad. But the
good side of it is we got ourselves into so
much of this mess that just shows you the potential
of human technology. Like, look at what we can do. Granted,

(35:28):
we screwed things up here, but we imagine if we
use that same level of energy and intensity towards a
corrective measure. Yes, though I want to be clear that
so we're not misunderstood here. We are not advising people
to hang their hat on like a potential like Holy
Grail technology that will get rid of all the carbon
or something like that. That is not a gamble that's
worth playing with. I think they're talking about like other

(35:49):
energy technology, other energy technologies, and also just like corrective
measures like and a willingness to change in that case. Yeah, absolutely,
But I don't know, I mean, I I do think
like this is a different kind of thing than climate change,
because climate change is something that we're like, we're we're
like near certain about some types of effects that are
coming within a you know, compared to this a relatively

(36:10):
short time scale. They're like almost definitely going to happen
within decades or a hundred years or something, and the
effects will be catastrophic. So that's like you'd probably say
that's actually a higher priority, but but this is a
different priority, so that it's like a catastrophic tail risk.
It's unlikely that we would get hit by an asteroid
like this anytime soon, but if we did, it could

(36:32):
be really bad, right of course. That The other obvious
thing to point out is that asteroids have mostly, if
not entirely and thankfully not been politicized. Oh yeah, so
nobody is out there saying why aren't we why are
we charting the asteroids? Like look at the I mean they,
I mean, you could easily imagine somebody taking up this

(36:53):
is is there. They're they're horrible battle cry and saying,
look how much we're spending on space exploration, Look how
much we're spending on this, on on watching the movements
of the asteroids, and look at these astronomical chances that
anything is going to hit us. Well, the unfortunate fact
about the politicization of science is that it does not
require both sides in order to happen. You can asymmetrically
politicize and currently non political issue, you know, just by

(37:18):
having one side get worked up about it, and then
of course the process is irreversible. And so please don't
do that with the planetary defense and stuff about, right, Yeah, hopefully,
I think planetary defense should be something that we that
everybody can agree on, and we should all like everybody
should be able to agree, Yes, this is a this
is a good investment in our future. It's like having
a lock on the door to your house. Yeah. But

(37:40):
then again, the exact same thing should be true about
alternative energy and climate change and stuff, and it's true
not I mean, clearly, what is in our interest to
de politicize does not correlate to what people actually do
de politicize. I think hopefully one I think one thing
in our favor here is that, as we've discussed on
the show, one of the problems with climate issues is

(38:01):
that it's it's very difficult for most of us to
wrap our hands heads around all that's happening in this
vast chaotic system of atmosphere and uh in climate. You know,
it's particularly when you're dealing with with larger periods of time,
oh and asteroids more like an easy to identify villain.
It's like it's like a rock thrown at your head.
Like we can instantly be like, yeah, like i'm here,

(38:22):
that's there. That should not hit where I am, and
like we can all agree that that that this this
is a bad thing, that should be that the big
should should be avoided at all costs and easier to
process in the mind, it's an incoming projectile, and we've
we've evolved to deal with that kind of threat. That's
a really good point, and I think it's absolutely, of

(38:42):
course worth investing in planetary defense at multiple levels, by
the way, probably most importantly right now, and expanding our
surveying capabilities right to increase our ability to catalog and
track near Earth objects, which we're already doing a pretty
good job at with Earth based telescopes and all that,
but expanding those capabilities it sounds like a very good
idea to me. And then I guess the next thing

(39:03):
on top of that is something that maybe we'll talk
about at the end of the episode, is what would
we do if we did detect something? You know, pretty
we did have fore warning, we're pretty sure something's on
a collision course with Earth. Is there anything we can
actually do about it? Right? All right, well, let's take
another break and when we come back, we'll discuss our
general state of preparedness for small near Earth objects and

(39:24):
then yeah, what what we would do if something did
seem to have our name on it? Thank? Thank Alright,
we're back. Okay, So Robert, we need to talk about
what we would do if we got some bad news
about a an asteroid uh coming down the pike in
our direction? All right? Well, yeah, well first let's let's

(39:44):
let's touch again on our general state of preparedness. So,
like we said earlier, of extinction, class near Earth objects
and eos are are marked, and it works out in
our favor because the bigger ones are easier to see.
Exactly fortunate our ability to to track these things has
certainly come a long way. Like I was reading about
how in observations of the asteroid n XF eleven suggested

(40:11):
that this half mile wide object would just simply hit
the Earth in. Only later did it turn out, via
better orbit analysis that the Earth actually isn't in danger
from this particular asteroid. So it was just you know,
more or less taken off the list based on our
current data. NASA has a sort of rogues gallery of
potentially dangerous asteroids or UM, you know, also known as

(40:34):
p h as fause potentially has dis asteroids, that's the
abbreviation UM. And these are ones that are predicted to
you know, to make close passes, such as say feet on,
which made a close pass in twenty seventeen, and we'll
make a closer pass in but we're talking about a
twenty seventeen distance of what, let's see, ten million, three

(40:58):
d and twelve thousand and thirty four kilometers or six million,
four hundred and seven thousand and six hundred one miles
and then uh, the next pass, we're going to see
it come in at two million, nine sixty four thousand
kilometers or one million, eight hundred forty one thousand miles,
which is still again close enough to be of concern.
But again this is just a to to really drive

(41:20):
home the distances we're talking about here. So there are
a number there are a number of potentially hazardous asteroids,
but even the more hazardous ones have a pretty low
chance of hitting the Earth. One of the biggest known
dangers out there right now, for example, is two thousand
s g threety four, which has a one and eleven
hundred chance of impact in one and again I come

(41:41):
back to that question. You might are you might be
cool with those odds, but are you cool with the steaks?
It's again easier to spot the big civilization busters, and
that's where that nine tracking rate comes in. But according
to the Planetary Society, which has a has a number
of wonderful um uh educational resources on space, experty and astronomy,
we're only tracking like twenty thousand out of a million

(42:05):
smaller but potentially deadly pH s. So we need to
improve our tracking capabilities right for these again, to deal
with these potential city busters, especially, So I suppose the
answer is that you know, we're doing better than we
ever have, but there's a lot of room for improvement
and lots more room for certainty when the stakes are

(42:25):
this high. And this is also a very important reason
to always support and vote for political candidates and parties
that value science, scientific consensus, and h and manifest that
support for science in the form of policy and funding. Now,
the next question is, okay, what if we what if
we do spot one that is just coming way too
close for comfort? What are we prepared to do about it?

(42:47):
And this is an area where various plans have been
presented over the years, and it's really like it's one
of these scenarios that that you really get the sense
that a lot of you know, astronomers and science is
really relish. The problem is a pure thought experiment, like
what can you do to to deal with an asteroid

(43:07):
that is on course to hit the Earth or getting
way too close to the Earth for our comfort level?
So you get Bruce Willis, Oh, no, I'm sorry, I
made that joke. You know. I was like, I'm gonna
go this episode without referencing arm Agin, and then I
just did it anyway. Yeah, well, I've never seen Armagin,
so I can't I can't even chime in on that.
I don't know if it's worth your time. But I've

(43:27):
seen chronicles of Riddick and that had that had a
dangerous sort of near Earth object like the Necromonger spaceship.
As a comment, right, oh man, those those rat tail
braids on Carl Urban's head, and that that is the
near Earth object that I'm most worried about. All right,
So a near Earth object coming at the planet. What
can you do? Well, all the all the proposed solutions

(43:49):
tend to fall under one of two categories. Either you
destroy the near Earth object, fragmenting it into smaller chunks,
or you alter its trajectory. I am of the you know,
I'm not an expert in this realm, but I'm of
the opinion that one of the forks of the stile
emma is much better than the other. Well, blowing it
up is certainly very you know, I think it's an

(44:09):
ego inflate inflating option to be sure, you know, launch
a nuke, get into that puppy and just make it
go boom. Right. Of course, the thing is this fragments
the larger ineo into smaller chunks that you know, hopefully
if you're dealing with a small enough ineo, you know,
you're you're breaking it up into chunks that will then
just burn up in the atmosphere should you hit the atmosphere.
But you know it's also you could look at it

(44:31):
another way and say, well, it's a bit like turning
an incoming slug or an incoming bullet into an incoming
blast of buckshot. Right. According according to Alan Duffy, one
of the researchers we mentioned earlier, he was quoted in
the Washington Post saying that this option of nuking it
and blowing it into pieces, he says, quote, it makes
for a great Hollywood film. The challenge with a nuke

(44:52):
is that it may or may not work, but would
definitely make the asteroid radioactive. Okay, so radioactive buckshot? Ye
coming I ship Now. The more popular ideas involve changing
the ineo's trajectory, and these range from crashing another object
into it so like croquet or Billard style, you know,
to gently gently nudging it off course. This is generally

(45:15):
known as the kinetic impact, but you could also use
nukes for this as well. It should be point out
like if you were to use a nuclear device to
deter to deflect an asteroid, you wouldn't have to like
blow it up. You could just create an explosion in
a close enough proximity to it to try and nudge
it off course. Yeah, so you could, you know, of
course you could have a kinetic impact or an explosion

(45:37):
try to divert its course. Another often discussed solution is
what's known as the gravity tractor. Oh yeah, I really
like this one. So this involves flying a probe out
to meet the asteroid and then having the probe simply
fly alongside it. And remember that gravity works both ways.
It not only attracts smaller bodies to larger ones, it
also attracts larger bodies to smaller ones. For example, in

(45:59):
our Solar System, the planets actually do exert a small
gravitational influence over the Sun, causing it to sort of
wobble in place, and the same would be true here.
Over time, if you have a small spacecraft flying next
to an asteroid, the asteroid would feel a slight gravitational
tug toward the mutual center of gravity that shares with
the probe flying alongside it, and this gravitational tug would slowly,

(46:23):
over time nudge the asteroid off its trajectory and something
about the solution is kind of beautiful to me, and
I can tell from the way that many astrophysicists talk
about this they kind of feel the same way. I
often see the gravity tractor described with the word elegant.
I feel like it's kind of the Pixar solution because
I can imagine it as a Pixar short the big
grumpy asteroid that's on its way to destroy us, and

(46:46):
we solve it not by launching a weapon at it,
but by sending a robot friend. It gets there, it
gets a manic Pixie gravity tractors, and and then it
just over time, you know, it gradually steers off course
and chooses a new path in line. Now, the key
to either of these, whether it's kinetic impact or or
gravity tractor, if you're trying to divert the trajectory, the

(47:07):
key is lead time. The earlier you detect a potential
threat asteroid, the easier it is to divert. Kind of
like if you imagine you're trying to knock off the
aim of a gun. If it's at point blank range,
this is a lot harder, you know, because the gun
can move around a lot and still hit you. If
it's a very long range, an extremely tiny nudge will

(47:29):
cause a miss right just because of the distance. You know,
it goes wider and wider as it gets farther and
farther away. Yeah, so it means that if you if
you had advanced knowledge and you had the ability to
send something out there to it some sort of probe.
There are a number of more elegant solutions that present
themselves that don't involve massive explosions and big kinetic strikes.

(47:49):
Uh So. Individual strategies involve everything from a fixing rocket
boosters to to an object to one of my favorites,
simply painting it white. Because consider if if an object
were were darker, it would reflect something like the sunlight,
but a white coat of paint. You see that number
go up to about so altering the way photons of

(48:11):
light interact with an ineos surface, either through paint another
way that is sometimes there's been a suggested is through
solar sale shading. So move some sort of large solar
sale device essentially a big space umbrella between the sun
and the asteroid, or use lasers, etcetera. And this would

(48:32):
allow you to mess with the Arkovsky effect. Now, the
Arkovsky effect, this is the NASA definition. Is it's name
for a nineteenth century nineteenth century Russian engineer who first
proposed the idea, and that is that a small, rocky
space object would, over long periods of time be noticeably
nudged in its orbit by the slight push created when

(48:55):
it absorbs sunlight and then re emits that energy is heat,
which is pretty which is pretty wonderful to think about.
It's like you don't have to send out at a
bomb or or a robot to mess with it, and
like strap rockets onto it. All you have to do
is send more or less light and you can alter
the trajectory of this asteroid. But again, all of these

(49:16):
these options are highly dependent on having lots of lead time,
knowing way way in advance that it could be coming
our way. And this is yet again why the most
important thing in all of these solutions is improving our
survey and detection capabilities. I think we should come up
with with an asteroid character right now that can be

(49:37):
our stand in villain. So when the asteroid, when the
one appears that is a threat. We've got a ready
made like character in our mythology to pair it up with, right, Yeah,
you know, like, so you mentioned the Pixar movie you
gotta have the grumpy asteroid that gets paired with the
Manning Pixie space probe. Well, uh, you know, there are
a few different ways you could go in that. In

(49:58):
that in that area, I mean, obviously one turns to
comics and you think of of say, oh, what's the
big Marvel guy, the planet guy Galactus? Galactus is a
wonderful stand in for some sort of enormous cosmic threat.
Does Galactus eat planets? He eats planets? Seems the other
way around. Well, I mean it's like it's like a
poison pill that our planet would eat. Well, I think
the thing is, once Galactus gets to your planet, it's over.

(50:22):
Uh you know, it's it doesn't really matter exactly how
he you know, what happens. You just know you're doomed.
And and that's kind of the scenario with a significantly
sized asteroid. But one thing I do keep coming back
to with this topic, and I have over the years,
it's like we're talking about an actual threat to the
planet and efforts to mitigate that threat and to prevent

(50:47):
any of any objects from hitting us. And it's like
it is ultimately such a noble venture and again one
that we can all get behind and all celebrate. And
really it kind of serves as as an example. I mean,
it's it's almost like a perfectly romantic, uh simple problem
to have and in many respects, like, yes, they're technological

(51:09):
hurdles to overcome, but unlike so many more complicated problems
in uh, in human events and even in the you know,
the health of our planet, like, it's something with a
clear cut threat and some some basic steps that we
can continue to take to try and mitigate the danger.
I agree. It's like it's like the one noble war.
It's a you know, a war. It's a fight for

(51:30):
our lives, but without a human enemy. Right. Yeah. And
and also the next time you hear a bit of
space news that doesn't just completely like you know, fill
you with wonder and excitement where you're like, oh, well,
that's just I'm not particularly you know one over by
that it doesn't like, you know, fill me with the
zeal for space. Think back to the fact that it's

(51:51):
that's all a part of our ongoing attempt to better
understand understand our our local and overall uh you know,
galactic neighborhood. And by doing so, you know we're able
to protect the planet from threats like this again, to
protect ourselves against the wrath of Galactus or the wrath
of act Yeah, all right, we're gonna call it right there.
But as always, if you want to check out more
episodes of Stuff to Blow Your Mind, head on over

(52:12):
to stuff to Blow your Mind dot com. And if
you want to support the show, the best thing you
can do is rate and review us wherever you have
the power to do so, and make sure you have
subscribed not only to this show but also Invention, which
is the other podcast that Joe and I host, where
each episode, one episode a week, we look at a
different invention from human techno history, discuss where it came from,

(52:33):
what came before, how do we possibly live before we had, say,
a toaster? And then how was life change forever afterwards?
Huge thanks as always to our excellent audio producer Maya Cole.
If you would like to get in touch with us
with feedback on this episode or any other, to suggest
a topic for the future, for just to say hello,
you can email us at contact at stuff to Blow

(52:54):
your Mind dot com. Stuff to Blow Your Mind is
a production of iHeart Radio's How Stuff Works. For more
podcasts for my heart Radio, visit the iHeart Radio app,
Apple podcasts, or wherever you listen to your favorite shows.