All Episodes

October 8, 2020 42 mins

Daniel and Jorge talk about the vast and amazing Oort cloud, and whether it is throwing snowballs at us.

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

See omnystudio.com/listener for privacy information.

Mark as Played
Transcript

Episode Transcript

Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:08):
Hey, Jorgey, what's your favorite Solar System object? I'm gonna
have to go with the Earth because you know, it's
the only one I've been to, so you're not a
gas giant kind of person. Depends how many tacas I
had for munch. But what if I do? You do
you have a favorite? I'm a big fan of the
Sun and everything it does for us here on Earth,
But my favorite thing in the Solar System is actually comets.

(00:31):
Comments what have commets done for us? Well, they're like
cosmic snowballs, and actually most of Earth's water turns out
to be melted comets. I guess water is pretty useful
to have. But wait, are you saying the Solar System
is having a snowball fight. Yeah, it's more like deadly
planetary dodgeball. Hi am more Hammon, cartoonists and the creator

(01:07):
of PhD Comics. Hi. I'm Daniel. I'm a particle physicist,
but I have strong opinions about various Solar System objects.
And Welcome to our podcast, Daniel and Jorge Explain the Universe,
a production of I Heart Radio in which we talk
about everything that we know about the universe and everything
that we don't know about the universe, everything that makes
us wonder and everything that makes us go huh. And

(01:28):
we explain all of it to you because we think
that your curiosity is as valuable as the curiosity of
scientists working on the front line. Yeah, and there's a
lot to be curious about. The universe is full of
amazing and incredible things and a lot of mysteries, a
lot of things that we don't know where they come from,
or what makes them what they are, or why they're there. Yeah,

(01:51):
And a lot of great scientific discoveries begin with pretty
simple questions, you know, like why is that thing there?
Or why are those common? It's flying through space and
where do they come from? Is one of them going
to hit us and wipe us out? Great scientific discoveries
come from really simple questions that everybody wants to know
the answers to. Yeah, because we have questions even about

(02:12):
our own backyard. Our solar system is still full of
things that we don't quite fully understand. People like to
talk about things in the distant universe that are still
a mystery. We don't know how big it is or
what's going on out there in the depths of the universe.
But you're absolutely right, there's still a lot to be
discovered right in our own neighborhood, big questions about what's

(02:34):
going on in our own household that we still don't
know the answers to. So they know you have a
strong opinions about things in our Solar System? Are they
all positive or are some of them negative? Is there
someone you don't like here in system? Now? They're all positive.
I love everything in the Solar System, from ice giants
to planetism als, to space centaurs, to deadly comments to

(02:57):
enormous burning balls of gas. I just think it's all
pretty awesome. I can't imagine having a negative opinion about anything.
Do you include in that all the people on Earth too? Yes?
I love everybody. No, it's incredible when you look out
there in space that you see so many beautiful, amazing things.
Like when was the last time you looked at something

(03:18):
out in space and you thought that's just kind of
you know, it's all just sort of like incredible and beautiful.
You know, whoever the universe's visual artist is, they're doing
a good job. Although you know, we live in California,
so right now, when I look up at the sky,
it's mostly smoke. Well, then take a journey through the
Solar System with your mind's eye. Yeah, there are a
lot of big questions about the Solar System and how

(03:38):
we got to where we are. And one of those
big questions about our Solar system is where do comets
come from? We don't know a comet factory here in
our Solar system, do we We don't know of a
comet factory. It could be that there are aliens out
there in the outskirts of the Solar System packing up
ice balls and shooting them at Earth. Or it could
be that they come from something else, something deep out

(04:01):
there in the Solar System. That's basically a huge reservoir
of comets ready to fall in, screaming towards the Sun
and boiling. And this is a big question because some
people think that most of the water on Earth came
from comets. That's right, Commets are mostly ice. You know,
something a lot of people don't understand about the universe
is that water is not rare. We talk about liquid

(04:25):
water being something we're looking for in the surface of
planets to see if there's alien life, but water as
a chemical, there's tons of it out there. There's like
planet size blobs of it. So most comets are icy
planetism alls. They're just big balls of ice, and some
of them fell towards the Earth in the early days
and landed and melted and formed our oceans. Thank goodness,

(04:47):
because that's where life came from. Right, we had them
in for those snowballs, and we wouldn't be here, that's right.
So next time you put your lips to a glass
of melted comet, remember you're drinking. The outer Solar System
are melted common Right, next time you go somewhere in
order a drink, order sparkling melted comment and see what
they do. Yeah, So a big question is where they

(05:09):
come from, and so scientists have a potential answer to
that question, right, Daniel, that's right. They don't know for sure.
Nobody's ever actually seen it, but we've given it a name.
So today on the podcast, we will be asking the question,
what is now Daniel? Is that pronounced or or or

(05:29):
because it's spelled O r T. It's a great question,
and it's a Dutch name. It comes from a Dutch
astronomer who first thought it up. And so I reached
out to my Dutch speaking brother to ask him for
his preferred pronunciation because I didn't know is it ort
ort ort or something like weird Dutch vowel that we
don't even have in English that can never be replicated?

(05:51):
Keep going, keep going? Well, you know there are vowels
in Danish that you know you can only replicate. You
get like punched in the gut in exactly the right way,
like you Dango speakers out there know what I'm talking about.
But it turns out that or its spelled o o
rt is pronounced like port. All right, So it's a

(06:11):
cloud apparently of some sort, and it's I'm guessing it's
out in space, and so the big question is how
many people out there know what it is and what
its significance is. That's right? So I pulled our listeners
who have volunteered to answer random questions over the Internet
from a businessist they've never met. If you'd like to
participate in such absurd commentary on our physical universe, please

(06:34):
write to me two questions at Daniel and Jorge dot com.
And thanks to everybody who shared your speculations. Think about
it for a second. If someone asked you what the
orc cloud is, what would you answer. Here's what people
had to say, The or Cloud is one of the
outermost regions of the Solar System, comprised of we think

(06:55):
a bunch of remnants of the early Solar system. The
Orc Cloud is a group of like dust and rocks
and asteroids and just material that's way outside are encircles
our whole Solar system. I think in a giant sphere,

(07:16):
or maybe just a circle. The art Cloud is a
vast array of comets and other such I see debris
forwarding around the Sun, very far away from the rest
of the planetary systems. I know that the Sun, it's
the middle of it, and it passes our solar systems,

(07:38):
so passes Pluto. Is it the big cloud of dust
that I'm spewing out the top and the bottom of
the Milky Way? I have anything to do with equippable?
Probably close to the Solar system. I think the art
Cloud is like an area outside the Solar system where
there are some icy objects. I'm not sure what, probably

(07:59):
comets and things like that. All right, some pretty good answers.
Most people seem to know it's something related to our
Solar system, and that it's a cloud, and that maybe
there's ice involved. Yeah, exactly, it's something big and fuzzy
and out there and cool. Cool. And my favorite thing
about the Orc cloud is at the acronym the O
C is the same as the place I live, Orange County,

(08:23):
except it's a little warmer, I think, a little warmer,
but it's also still very very cool. That's the first
time I've heard you give a compliment to the Orange
County there. I love Orange County. Best place in the
world to live. Seriously, what could you complain about? But
that's not the topic of today's podcast. We're talking about
the cosmic o C, the solar systems O C, not

(08:46):
calibornias o C and to uh, it's apparently something out
in space and so Daniel, let's step people through it.
So what is the orc Cloud? The orc cloud is
super awesome. It is a theoretical cloud of icy planetisml's
or many planets planetismal. Did you just make that up
or is that the actual science terms? Oh? Man, I

(09:07):
wish I could have made that word of there's something
wonderful about just saying that word planetismal. Right, but no,
planetismal is a mini planet and it's smaller than a
dwarf planet. Right, You've got planet dwarf planet, and then
planet Tismal. They couldn't just say mini planet. Well it's
sort of like Planetino, you know, that's what you do
with English planet Tito. And so it's a bunch of

(09:28):
these and they're really really far out there. Like if
you have the Solar system, you know, the Earth is
at one AU call an astronomical unit, and you go
really far out you get out to like Neptune and Pluto.
You have to go much, much, much further before you
get to the arch cloud. Is it even considered our
Solar system or is it technically outside of our Solar system? Yeah,

(09:51):
it's a great question. Most people consider the end of
our Solar system to be just under about a hundred
a U, where the sun radiation becomes dominated by the
galactic radiation. How you think of space is sort of
like empty, right, but actually it's filled with streaming particles.
The Sun is pumping out particles, not just photons, but

(10:11):
protons and electrons and all sorts of crazy stuff, and
it dominates the region around it with all of its
pulsating radiation. But the rest of the galaxy also has
a wind that's coming from all the other stars in
the central black hole. And all that crazy stuff. So
we define the edge of the Solar system it's called
the helio pause, as the place where the Sun's radiation

(10:33):
stops dominating the local environment and you're taken over by
the galactic wind. And that's like a hundred or so A.
It's like when our Sun becomes just another star kind
of yeah, exactly, and the wind from the rest of
the galaxy takes over the Sun's wind. And here again
wind we don't mean air, We just mean the particles
that it's shooting out. But the rac cloud starts like

(10:54):
ten times further out than that, like at a thousand
a U. Now it's just still sort of like bound
by the gravity of the Sun, or is it pretty
much like an independent thing from our solar system. It's
definitely bound by the gravity of the Sun. So if
you define the edge of the Solar system by the radiation,
it's like a hundred a U. But stuff that's further

(11:17):
out is still gravitationally bound to the Sun, but it's
a little bit loose. It's like a little fuzzy. It's
so far out from the Sun that it's not that
hard to knock something off and have an escape into
interstellar space, so it's not orbiting around us. It's sort
of like we're tugging them and it's tugging us. It's
definitely orbiting around us. Think of it like a huge

(11:39):
shell surrounding the Solar System. The other fascinating thing about
it is that it's not a disk, right, Most of
the stuff in the Solar System is a big disc,
it's flat. But the Orc Cloud, we think, is a sphere.
It's like totally surrounding the Solar System, and it goes
out really really far out to like a light year
maybe two light years of just this like cloud of

(12:00):
little frozen objects, and there could be like trillions of
the planetismal, trillions of planetism many planets I'm sorry, yeah,
planet titos. And it's sort of like calculus. You know,
in calculus, you sum over infinitismals and you get like
an actual quantity. In the same way, if you sum
over all the planetism als in the ord cloud, you
get a combined mass of stuff that's like five times

(12:22):
the mass of the Earth, but then again spread out
into like trillions of objects. It spread out not just
like wide but tall to like it's it's pretty diffuse
it's very diffuse, Like it's not like flying the millennium
falcon through an asteroid field. You gonna like dodge and
weave right, it's like, could we see something, like is
there one there? It's so far out there, it's mostly empty.

(12:43):
But again, they are gravitationally bound to the Sun and
they are orbiting the Sun. That's why they are in
a cloud around the Sun. It's not like just the
whole interstellar medium is filled with these objects. It's a
cloud of them. We think. Again, we think we don't
know for sure. We haven't seen them because they're so
small and far away, but we think that they're there
in this big blob around the size see, and it's

(13:04):
made up of like giant literally like giant balls of ice,
basically snowballs. How big, Well, each one could be like
bigger than a kilometer in size, So we think that
they're like trillions of them that are more than a
kilometer and maybe only billions that are twenty kilometers are larger.
But if you wanted to have a cosmic snowball fight,
that's like where your arsenal is, that's the best place

(13:25):
to go for the stockpile. Wow, So that's like, let
me see, that's like a snowball about the size of
Los Angeles right kilometers. Yeah, there are billions of frozen
Los Angeles is out there in the o C because
they are pretty cool, icy cool. They are pretty cool,
and if they weren't gravitationally bound to the Sun, they

(13:45):
would just sort of float away into space. But they
are bound there. They're floating around, but you know, it's
sort of loose, and so sometimes the thought is sometimes
something perturbs them and then they can get knocked out
of their very loose orbit and plummet towards the inner
Solar System because they're in a stable orbit. Is that
the idea is that they're like happily going around our

(14:07):
Sun in this huge, wide orbit, but sometimes they can
fall in. Yeah, we think it's probably stable and if
nothing perturbed them, they would just happily hang out there
really far away, staying frozen. But you know, we are
in a little neighborhood, and since it's sort of loosely
held by the Sun, it's not that hard to perturb them.

(14:27):
And you can have things like galactic tides that squeeze
the orac cloud and knock some of them out of orbit.
You mean from the center of the galaxy. Yeah, just
the way the Moon has a gravitational effect on the
water of the Earth. So as the Moon goes around
the Earth, it tugs on the oceans and causes tides.
We have a gravitational pull towards the center of the galaxy,
and that tends to tug on one part of the

(14:49):
Orc Cloud that's closer to it more than the rest
of the Orc clouds, so sort of extends it. And
then as we move around the center of the galaxy
very slowly, you know, hundreds of millions of years, the
direction of that tug changes, so it's a dynamic. So
as we move around the center of the galaxy, the
tides change, the galactic tides change. So are we right
now and high tide or lord tide. Well, we're at

(15:17):
the center of it right so we wouldn't feel it
at all. But there's a blob of the Orc cloud
that's always pointed towards the center of the galaxy that
would be at high tide. There's more objects in that
part of it, so we're sort of at the very
center of it, so we can't tell, but it can
be galactic tides. It can also be like nearby stars.
If a nearby star happens to come somewhere close to

(15:39):
us as we all swish around the Milky Way, it
can perturb the orc cloud and send comets falling in
towards the center of the Solar system, right or steal them,
possibly steal them, or steal them absolutely, and we'll talk
about where these came from. It's not clear that all
of them actually came from our Solar system. And I
guess the thing is that we've never actually seen the cloud, right, Like,

(16:00):
we don't have pictures of it or even like radar
of it or evidence of it. That's right. It's so
far out there that it's still theoretical. There have been
some glimpses of one or two objects that people debate
might be like part of the Inner Inner Inner or cloud.
But these things are really small and really really far away,
Like it's hard to see Pluto, right, and Pluto is

(16:22):
really close compared to these things, and nothing that we
have out there in the Solar System has gotten anywhere
close to them, Like the thing that we have sent
out into space, that's the furthest object the humans have
ever built, that's Voyager one. The fastest human spaceship ever. Right,
that thing won't get to the beginning of the Orc
Cloud for another three hundred years. Well, Daniel, I don't

(16:46):
know if I believe in this thing or not, but
let's get into how we know it's actually there and
why we think it's important for our origin as a
planet and as a human species. But first, let's take
a quick break. All right, we're talking about the or Cloud,

(17:14):
which is uh. I guess Daniel, you would describe it
as like a giant shell of city size snowballs floating
out hundreds of light years away from the Sun. That's right,
And snowballs makes it sound quaint and fun and like
if you get hit by one, you can just go
inside and warm up with a cup of hot cocoa. Right,

(17:35):
But these things are massive ice balls, and if one
of them hit the Earth, we might be toasted. So
we'll talk about the danger these things later on, but
I want to make sure people are aware that these
are basically massive space bullets waiting to hit the Earth.
It's like a real snowball. If they pack enough ice
into that slush ball, it can really hurt. Yeah, alright,
so how do we know that it's actually there. Then

(17:55):
what makes us think that there is this giant cloud
of snowballs in space? Well, it comes um sort of
a paradox. In the last hundred years, we've established that
there are lots of comets, but the Solar system is
not very young, and so people have been wondering, like,
where do all these comets come from? Because comets are
not stable. Like, once a comet starts falling in towards
the Sun, it loses a lot of its mass as

(18:17):
the Sun boils it away. So a comet can't like
zip around the Sun for billions of years. It only
gets like, you know, fifty or a hundred, maybe two
hundred times around before it gets boiled away. Right, So
if that's the case, if comets don't last very long,
why are we still seeing commets? Like you lived in Arizona,
and every once in a while somebody throws a snowball

(18:38):
at your house, You're like, this is recent, Like somebody
just made this. Yeah, Or you know, if you're walking
around your neighborhood and everybody's eating ice cream, you're like,
where's the ice cream? Chuck? It must have just come by.
And so exactly, they thought there must be some sort
of source of these things. The other clue was that
there's sort of two types of comets. There are short

(18:58):
period comets. Com is to have an orbit around the
Sun that's like less than ten a U, and these
are mostly aligned with the Solar System. It seems like
they're like basically Solar System objects, just blobs of ice
somewhere in the outer reaches of the Solar System. But
then there's a second group of commets. They're called long
period comets. These are ones that have an orbit that's
like a thousand a U or more, and they take

(19:21):
a long time to go around the Sun, and they
don't follow the plane of the Solar system. So these
were really the mystery. They're like, where are these long
period comets coming from? They couldn't explain it. They shouldn't
stick around. And so to explain where the new ones
were coming from, they said, maybe there's a huge blob
of them somewhere out there beyond where we can see. Oh,

(19:41):
I see, you're saying these long period comments. They're sort
of coming out of left field. Doesn't look like they're
hanging out with us, or have been hanging out with
us for a long time. It's like they're coming from
somewhere else. Yeah, because they can't last for very long. Like,
once you see a comet, you're seeing it in the
end of its life cycle. It could have been out
happily for billions of years deep out there in the

(20:02):
Solar System. But once you see it, that means it's
falling towards the Sun and it's going to get boiled
away as it goes around the Sun, and it can't
survive for very long. And even if it does make
it a hundred or two hundred orbits, it's got a
high chance of getting kicked out of the Solar System
being perturbed by the gravity of one of the outer planets.
So once you see a comet, it means it's in

(20:24):
its last chapter of its life in the Solar System.
So we're still seeing comets four and a half billion
years into the story of the Solar System. There has
to be some fresh resupply every once in a while.
I guess if you're seeing a comment, that means it's
getting hit by the rays of the Sun, which is
probably melting it. It's definitely melting it, and that's where
the comets tail is. Right. People like to imagine the

(20:44):
commets tails like little action lines in a cartoon that
show you where it's moving. But the commets tail is
not actually pointed away from the direction of the comets motion.
It's pointed away from the sun because the tail comes
from the sun boiling away all the stuff on the comet. Yeah,
that's the signature tale of of comets. That's what it is.

(21:04):
It's not really a tail. It's more like a haircut.
Is that what you're saying, Yeah, precisely. And comets can
actually have multiple tales. They can have tales going in
different directions based on like the stuff that's in there
that's good and getting boiled away different compositions. So it's
pretty fascinating look at the tales of comets. It's pretty awesome. Okay.
So then someone named Yon Ord in the fifties said, hey,

(21:28):
maybe all of these weird long period comets are coming
from a very specific place. And so he came up
with this idea of the Ord cloud. Yeah, and he
looked at the orbits of these comets and he said,
how far out does it have to be to generate
comets with this length or but these long period comets,
And so that's how he estimated. He made a very

(21:48):
rough estimate for you know, how far away should be.
And since then we have much better data, better telescopes.
We can see the orbit of these comets much more clearly.
We have more telescopes, we have hubble and so be
can track all this stuff, and we have better estimates
for what's out there and how big it is. But
the basic idea came from this guy, yawned Ort in

(22:08):
nineteen fifty. And you know, it's pretty awesome to get
to put your name on the biggest thing in the
Solar system, Like this thing just dwarfs the rest of
the Solar system. Did he call it that the the
ord cloud or was it named after him? That's a
great question. I should read his original paper to see
if he put his own name on it or if
he was humble. Yeah, when he called the cloud of
Testimal and let somebody said that's a ridiculous name. We'll

(22:31):
go with orc. Yeah. And it's fascinating and it's cool
because it answers a question, right, It tells you, oh,
that must be where these comets are coming from. But
like everything in science, when you answer a question, it
opens up more questions, like all right, Well, where did
this ort cloud come from? Why is it there? Why
aren't they just closer into the rest of the Solar System.
And that's an active area of research right now. So

(22:52):
we actually haven't seen this cloud. We're just sort of
tracking where comets come from, and we think they come
from the cloud. Yeah, we have not seen this. We
don't have telescopes that are powerful enough to spot it,
none of our probes are anywhere near it. But it's
sort of the best explanation and we have for the
source of comets. So it's pretty well accepted in the

(23:14):
astronomical community that it exists. Like we always like to
see direct evidence of something before we conclude that it exists,
like there was evidence for Pluto before we spotted it
in a telescope. But you don't really claim discovery of
it until you actually see it, right, It's like finding
the body in a murder mystery. But sometimes it's the
best you can do for a while, so we can

(23:36):
talk later about like plans people have for how to
spot the Orc cloud and to study it, but for
now we have no direct evidence of it. I guess
it's not a thick enough cloud that it like makes
your view hazy, or you can see some of the
like the light getting filtered through it. It's not that thick, No,
it's not that thick. These things are very small and
very far away, so thick is definitely not how you

(23:57):
describe it. There's enormous that empty spaces between every object
in the orc cloud. Even though there are trillions and
trillions of objects. The space we're talking about is incredibly vast, Right,
We're talking about a sphere that's basically a light year
in radius, and so there's a lot of space in
there to distribute the trillion objects and still have lots

(24:20):
of room in between them. All Right, Well, I guess,
like you said, a big question is where did this
orc cloud come from? Like why is there all this
water deposited in one spot out there in the Solar system?
Beyond the Solar system. Well, as usual, we have a
few theories. We have sort of like the most boring
theory and then the most exciting theory, and the most
boring theory is sort of a story of the formation

(24:40):
of our Solar system. Like we start from a big
cloud of molecular gas and dust and stuff that collapses
and you get the Sun and you have a disc
of stuff that has too much angular momentum to collapse
into the Sun, so it spins around the Sun without
forming part of the star. And that's the protoplanetary disc, right.
And there you have of ice and gas and dust

(25:01):
and all kinds of stuff that starts to form planets
and clump together and form all sorts of stuff. The
idea is that not everything clumps together to form a planet,
like you have asteroids for example, of smaller things. Gravity
doesn't succeed in clumping everything together. But you do get
big gas giants out there, like Neptune and Urineus and

(25:22):
Saturn and Jupiter. They start to be sort of like
heavyweights of their own gravitationally, and they can perturb the
other stuff. And so there was a bit of a
dance in the early Solar System as these big planets
we're finding their place, and as they move around, they
affected everything else. So the short version of the story
is that we think that they were essentially tossed out

(25:43):
of the Solar System by some of these gas giants
as they were being born. These planets sort of like
muscled their way around the craziness of the Solar System. Yeah,
and one of the definitions of planets, if you believe
in you know, silly astronomical categories, is that it's cleared
its own path around the Sun. And so that's just
sort of like the job of growing up and being
a modern planet is that you have to like toss

(26:05):
the little bits out of the way, or you know,
slave them and make them into your moons. But in
this case, most of the stuff we think was tossed
out sort of in the early days of the Solar
System formation. And it also it had a reverse effect.
Remember gravity is always two directions. So we think that
one of the reasons that Neptune is as far out
as it is is that it got tugged out by

(26:26):
these objects as they were leaving the Solar System. I guess.
One question is if a planet is kind of plowing
through and sending things out into space, wouldn't it send
all kinds of things like asteroids and rocks and gas.
How did all this ice come together so purely, I guess,
And like, you know, why isn't it a mix of
all other things? Yeah, that's a great question. It is

(26:47):
mostly a mix, right, These things are not pure water.
It's like you go out there and you find these
pristine cubes of ice that you're ready to chisel out
and put onto your space cocktails. These things are dirty.
It's definitely still rocks in there. But remember that a
large fraction of the stuff in the outer Solar system
is ice, like you call uranus and neptune. They are

(27:08):
called ice giants, and so it's something of a matter
of how these chemicals are distributed through the solar system,
like where water ends up and ends up freezing and
gathering together. But a lot of the stuff in the
outer Solar system, and non significant fraction of all the
mass in the outer Solar system is water. I guess
out there most of it is ice and liquid, because

(27:29):
if it was closer, it would evaporate and maybe blow
out exactly. Some complicated arguments about where stuff in the
solar system collapses and what falls in and what doesn't.
But you end up with a lot of ice in
the outer Solar system. But these things are not pure water. Again,
they're definitely bits of rock. I would not recommend drinking
an or object if you found one, unless you like rocks,

(27:52):
unless they like your cocktails dirty. I guess they're dirty
snowballs all right, So that's one theory about how it forms,
just like you know, byproduct of the dynamics of the
solar system. What are the more interesting theories? The more
interesting theories are the interstellar theories. One idea is that
our son, when it formed, wasn't on its own. But
you know, we've discovered barely recently that a lot of

(28:13):
stars it was a twin. Yes, we're born as twins.
That binary star systems are much more common than we imagined.
So it could have been that our son had a
twin and that this collapsing cloud of stuff formed two
stars instead of one. But then these two sort of
drifted apart, as you know siblings sometimes do, and there's
a lot of material exchanged, and that gives you an

(28:35):
opportunity to sort of pull material further away from the
Sun because you have this big, heavy object, the other star,
tugging on your solar system. What so, what happened to
this other star, sister star. It's the subject of a
Netflix documentary, you know, where they're going to reunite the
stars for a dramatic conclusion at the end of the universe,
or a hit podcast mini series. That's right, not true crime,

(28:59):
but true physics. No, we don't know. It's just hypothetical.
We don't know that the Sun had a twin star
at its birth. It's just an idea. But if it did,
it could have been pulled off and gone in any direction.
It's been a long time, it's been billions of years,
and so it's hard to trace. It's not like the
nearest star is necessarily a category for our lost twin.

(29:20):
This thing would have been moving for a long time.
It could be anywhere at this point. And so the
idea is that the sister star pulled some things from
the Sun and then left it out there and where
the orc tod would be. Yeah, just like we were
talking about the gas giants tossing stuff out of the
Solar system, Now you have a much bigger object, a
heavier object, another star even further out. It's going to

(29:41):
tug out some of these stuff in our solar system
to have a very large radius. And then as the
to sort of separate. I'm imagining, like you know, sell
mitoses here two stars are pulling apart from each other
and it's sort of like threads in between them, and
then as they get far enough away, they stop affecting
each other gravitationally and things settle into place. But you
have stuff out at a pretty far radius because the

(30:04):
gravitational pull of the other star interesting. So it was
like the leftover from the divorce or something I just
got dropped there in the middle of space. That's right,
the poor abandoned objects in the stellar o c so
many seems appropriate. All right, let's get into our last
theory about where this orc cloud came from and what

(30:26):
it all means. The first let's take another quick break.
All right, Daniel, there's a giant cloud of snowballs out
in space about three light years away from the Sun,

(30:50):
and we think that's where comments come from. But the
question is where did this cloud come from? And so
you have one more theory for us about that, and
I'm going to guess it involves eight It involves alien stars,
though we don't know if there are aliens enough living
around those stars. The problem is that if you do
the calculations, and you have your theory of the Solar
system and you predict how many things there should be

(31:12):
in the or cloud, you get a number that's way
too small. You get a number like six billion objects.
But we know the number is much much bigger than that.
So the idea is like, well, where do these things
come from? So wait, how do we know how big
it should be? If we don't, we've never seen it
and it's all theoretical. Is it just from like the
frequency of comments that we get exactly to explain the

(31:33):
number of comments that we see, and they're radius and stuff,
there should be a certain number of objects in the
Orc cloud, otherwise we would see fewer and fewer comments.
But if we try to predict how many things are
in the Orc cloud from sort of first principles formation,
like how many things should have been tossed out there
by Neptune and Saturn Uranus, then we get a much
smaller number. So there's a discrepancy there. We know there

(31:55):
are objects out there, we can't explain how they got there.
So one idea is as well, when our star was forming,
what was going on nearby? We talked about how maybe
there was a sister star formed with us. But another
idea is that maybe our stellar cloud that collapsed was
near some other objects and it stole some material from

(32:15):
those objects. That basically the Orc cloud is like a
lot of stuff from other solar systems that was stolen
by our sun when it formed. What it could be stolen? Good? Yeah,
the water we're drinking could have been stolen from another
solar system. Is that what you're saying? You should feel
guilty every time you have a drink. It's elicit. But

(32:36):
it could basically be all a muamua, right, Remember Mumua
was this interstellar comment, this frozen object that passed through
our solar system coming from some other solar system. And
it could be that the Orc Cloud is basically just
a bunch of these. Oh I see, is that a
theory that Oma came from the Orc Cloud? No, mum
It definitely did not come from the Orc Cloud. Its

(32:57):
trajectory is totally inconsistent with that. We know that it
came from another solar system. But it could be think
the Orc Cloud is the product of stealing a bunch
of Omumua like objects much much earlier, a long time ago,
as our solar systems forming. So you know, possession is
nine tenths of the law. Then you know we've had
these for billions of years. They're basically ours now, but

(33:19):
there's a bit of original sin there and having stolen
them from another solar system a long time ago. Well, yeah,
I guess, because you know, I think the closest stars
to us our solar system are about what is it
like five light years away, right, yeah, three and a
half light years away to proximates Centauri. Yeah, so this
orc cloud is about where those other stars are. Yeah,
it's the right order of magnitude, right, it's that big.

(33:42):
It's so big that it gets you part way to
other stars. And those other stars probably have their own clouds,
and these stars tugging each other, and one of the
ways to perturb our or cloud is to have other
stars come nearby and give it like a little gravitational tug,
which results in comets falling towards the Earth. Also, an
orac cloud is not necessarily like a good thing. We

(34:02):
talked about stealing this, but like it's a bunch of
bullets hanging over our head where at the bottom of
this gravity, well, any of them roll down, they could
totally wipe us out, like deadly hail or something. You
don't You don't necessarily want that, it won't create a
winter wonder lamp. You want it early on, so we
can give you oceans, but then you basically want to
give them away. To your neighbor, so you don't have

(34:23):
them anymore. Wow. Alright, so it is kind of like
a giant interplanetary snowball fight almost or tug of war. Yeah,
and that's where we think most commets come from. And
you know, every time you see a comet that's come
from the outer Solar System, it's been out there for
billions of years, happily orbiting, not being close to anybody,
being an introvert. And now it's screaming towards the center

(34:45):
of the Solar System, maybe hitting a planet, maybe hitting
the Sun, maybe just whipping around and going back out right.
It's kind of dangerous. It's actually quite dangerous. You know.
People talk about asteroids hitting the Earth and worrying about
big rocks and planet killers and all kinds of stuff,
But the truth is NASA has most of those figured out.
Like most of the asteroids, the things in our Solar System,

(35:07):
we could see them because they're pretty close, certainly anything
that's big enough to cause us any danger. And NASA
has a great team of planetary protectors tracking these things
and predicting where they're gonna be and letting us know
if they're gonna be anywhere nearby, and often one of
them slips through and we don't see it until it
hits us. But that's because it's small. So a really
big object that would actually cause any damage. NASA is

(35:30):
pretty sure we're safe from those for a couple hundred
years because they're hanging out in the Solar System, so
we can kind of see them, but we can see them.
But if it's coming from outside the Solar System, then
it can surprise us. Yeah, if it comes from left field,
it could be a real surprise. These things could have
orbits that are hundreds or thousands of years, and so
the first time we see one might be the last

(35:51):
time we see one because it could be headed for Earth.
And so these things could fall into the Solar System
and smack right into a planet and you know, cause
a lot of destruction. Because they also they move really
really fast. They've been accelerating for a long time falling
in towards the Sun, and so they have a huge
amount of kinetic energy. This is not a gently tossed snowball.

(36:13):
This is like a rocket. It's like a rocket propelled
missile launched snowball. Yeah, you give like a really hard
block of ice to a major League pitcher and stand
right in front of the mess. He throws it at
your face. That's about how terrifying this is. Just like
when they threw those frozen turkeys at airplane to see
if the airplanes would break. Is that a real experiment
used to make that up? That's a real thing. They

(36:35):
shot frozen turkeys at an airplanes to see what would happen.
And it's happened before, right, Like our Solar system has
gone pelted by giant snowballs, and some of them even
hit some planets. Yeah, exactly. If you think, oh, that's
not likely to happen, or it might only happen every
thousand or million years, we don't know how often it happens,
but we do know that it happened recently. It was

(36:56):
in the nineties that a big comet hit Jupiter commt
Maker Levy. It broke up into a bunch of pieces
and each one pelted Jupiter, and even after it broke
up and made fireballs that were larger than Earth when
each one hit. So these are very dramatic planetary events,
not the kind of thing we want to have happened
to Earth. Yeah, that would be bad, It would be bad.

(37:18):
And now, Daniel, I have a note here in the
document you send me here, and I'm trying to figure
out it says also space centaurs, And that's it. What
does that even mean? Space centers are so much fun.
I decided to make it a whole other episode for
a few weeks from now. But there is this thing
in the Solar System called a space center. Seriously, it's

(37:42):
a thing. Scientists found the thing and called them space centers.
But they're not like you might imagine, maybe like you know,
asteroids that happened to look like the fusion between man
and horse. No, they're just the name that you give
small objects between Jupiter and Neptune that sort of cross
back and forth between the orbits of these gas giants,

(38:03):
sort of like transitional objects. So they're like we could
call them space unicorns or space griffins. That would be
too crazy, but we'll go with space centers. I don't
know what kind of bananas they were smoking the day
they came up with that name, but it did tickle
my sense of humor. But they think that maybe space
centers also have come from the orc cloud. They've essentially
fallen in and then into these more stable orbits somewhere

(38:27):
in the outer solar systems thing. Well, then I vote
we rename comments to space unicorns. I second your motion,
but I don't think we have any jurisdiction here. All right, Well,
it sounds like comments are pretty cool. They might be
coming from the Orc cloud, this theoretical cloud out there
in space which gave us water, which is a good thing,

(38:47):
but which may kill us in the future. And so
we're we're studying this cloud. Now we're studying comments more.
What are we doing about it? Well, we're doing everything
we can. It's pretty hard to spot these things right there,
so small, they're so far away. People have one really
fun idea for how to visualize these things, and essentially
it's to look for star eclipses. Like if we are

(39:09):
surrounded by this huge cloud of these little objects there
essentially black, they're so far away they don't reflect enough sunlight,
but occasionally they should pass in front of stars, causing
these little transitions where the star basically blinks out momentarily.
So you can look at all the stars and watch
them and wait to see if you see one of

(39:30):
these eclipses, and if you do, then you can use
that to measure like how many things there are out there,
but based on the rate at which you see these things,
And if you don't, then you can set a limit
and say, well, there can't be that many, otherwise I
would have seen them. You're looking at Like how the
stars are twinkling, Yeah, because they might be twinkling because
of a giant comment heading towards us, Yeah, or just

(39:52):
a giant, silent, frozen comment passing between us and that star.
And you know it has to line up just right.
You have to draw a line between the Earth and
that star super far away, and then the orc cloud
object has to basically break that line in order for
there to be this eclipse. So it's not that likely,
but there are a lot of stars out there and

(40:13):
maybe a lot of orc cloud objects, so if you
get enough telescope time, you might be able to spot it.
And unicorns are pretty magical, so you never know what
they're gonna do. What if they're all turned out to
be rainbow colored, that would be amazing. And it could
also be that if we pass nearby another star, that
that star could like pass through our or cloud, causing

(40:34):
like a new bombardment of comets, and that would be
sort of a confirmation because we'd see a lot of
these things rushing towards the inner Solar system. Well, clearly
we need to build like an ice Ford Daniel around
the Earth. That um, yeah, I think it's called Neptune.
That's an ice giant, and hopefully it captures these things
as they come into the inner Solar system. You know,

(40:55):
we actually do have the gas giants to thank for
protecting us from a lot of these things. They tend
to pull them in and they also tend to clean
them up. So without those big planets out there protecting
us from the o C bullies throwing snowballs, we would
have had a rougher time of it. And then, to
be ironic, if there was a like a giant comment
heading towards us, but then at the last minute Pluto

(41:16):
gets in the way and blocks it. That sounds like
the plot of our movie. That sounds like a good
slow motion scene at the end and flat and everyone's like, oh, Pluto,
we took you for granted, but now you see it
is all it's too late, but now we value your contribution,
all right. Well, the next time you look out into

(41:38):
the night, Skuy, we hope you think about what's out
there and what could possibly be out there, and also
think of ice unicorns floating out there in space. And
remember that there's a lot of things out there that
we still don't understand, sources of mystery, sources of wonder,
and sources of danger. So we better get on it
and figure this stuff out before it wipes us out,

(41:59):
or it might be too late. We're ready or not.
All right, Well, we hope you enjoyed that. Thanks for
joining us, See you next time. Thanks for listening, and
remember that Daniel and Jorge Explain the Universe is a
production of I Heart Radio or more podcast For my

(42:20):
heart Radio, visit the I heart Radio app, Apple Podcasts,
or wherever you listen to your favorite shows.
Advertise With Us

Follow Us On

Hosts And Creators

Daniel Whiteson

Daniel Whiteson

Kelly Weinersmith

Kelly Weinersmith

Show Links

RSS FeedBlueSky

Popular Podcasts

On Purpose with Jay Shetty

On Purpose with Jay Shetty

I’m Jay Shetty host of On Purpose the worlds #1 Mental Health podcast and I’m so grateful you found us. I started this podcast 5 years ago to invite you into conversations and workshops that are designed to help make you happier, healthier and more healed. I believe that when you (yes you) feel seen, heard and understood you’re able to deal with relationship struggles, work challenges and life’s ups and downs with more ease and grace. I interview experts, celebrities, thought leaders and athletes so that we can grow our mindset, build better habits and uncover a side of them we’ve never seen before. New episodes every Monday and Friday. Your support means the world to me and I don’t take it for granted — click the follow button and leave a review to help us spread the love with On Purpose. I can’t wait for you to listen to your first or 500th episode!

Las Culturistas with Matt Rogers and Bowen Yang

Las Culturistas with Matt Rogers and Bowen Yang

Ding dong! Join your culture consultants, Matt Rogers and Bowen Yang, on an unforgettable journey into the beating heart of CULTURE. Alongside sizzling special guests, they GET INTO the hottest pop-culture moments of the day and the formative cultural experiences that turned them into Culturistas. Produced by the Big Money Players Network and iHeartRadio.

Crime Junkie

Crime Junkie

Does hearing about a true crime case always leave you scouring the internet for the truth behind the story? Dive into your next mystery with Crime Junkie. Every Monday, join your host Ashley Flowers as she unravels all the details of infamous and underreported true crime cases with her best friend Brit Prawat. From cold cases to missing persons and heroes in our community who seek justice, Crime Junkie is your destination for theories and stories you won’t hear anywhere else. Whether you're a seasoned true crime enthusiast or new to the genre, you'll find yourself on the edge of your seat awaiting a new episode every Monday. If you can never get enough true crime... Congratulations, you’ve found your people. Follow to join a community of Crime Junkies! Crime Junkie is presented by audiochuck Media Company.

Music, radio and podcasts, all free. Listen online or download the iHeart App.

Connect

© 2025 iHeartMedia, Inc.