Episode Transcript
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Speaker 1 (00:09):
Ay, Daniel, When you were growing up, when did you
first realize that the rest of the world was not
like the neighborhood you lived in. Mmm, well, I grew
up in Los Alngos, where I was surrounded by people
with pH d s, and now I live on campus
at you see Irvine, also surrounded by people with PhDs.
(00:31):
Are you saying that's not typical? First of all, I
feel a little sad for you. The second, I think
maybe you need to travel more. Hey, I mean I
have lots of friends who don't have PhDs like me,
And you mean you do know I have a PhD. Right, Oh,
that's true. Actually, well, I'm sure one of my friends
out there doesn't have a PhD in something. Probably sometimes
(00:54):
you have to leave your comfort zone to discover what
the rest of the world or the universe is. Like.
(01:17):
Hi am or hand Ma cartoonists and the creator of
PhD comics. Hi, I'm Daniel. I'm a particle physicist by
day and a podcaster by night. It makes it sound
like you're a superhero. Like you you put on a
costume and you go and fight crime and discover things. Wait,
which is the alter ego and which is a superhero.
Ag are you saying particle physicists are superheroes or podcasters? Well,
(01:42):
since I'm not a physicist, I would say the podcasters
are the superhero. That's right. By day, a boring, run
of the mill particle physicists like the kind you meet
at your grocery store every day. No more like during
the day. You're a physicist scientists supervillain during night, then
you try to fix fixed by being a podcaster. That's right,
(02:02):
And I take off my glasses to reveal my secret
podcast identity. You shave your beard every night never. That
is the source of my knowledge and inspiration, source of
your source of professor male professor's powers. That's right. I
am the Samson of physics. Before I grew this beard,
(02:23):
I never achieved anything in science. Oh man, what if
you could a got Does that cut your productivity? You
can have? It's nonlinear. Well, welcome to our podcast, Daniel
and Jorge Explain the Universe, a production of I Heart
Radio in which we tackle all things about the universe
that are mysterious, that are amazing, that are bonkers, from
how the universe was formed, to how big is it?
(02:45):
To how old the Earth is, to whether or not
your facial hair determines your evil or innocence yep. Or
whether being a podcaster makes you a superhero or not.
I think we all know the answer to that one.
But basically, we talk about all the things that are
interesting and different and fascinating about our universe right especially
(03:08):
the things around us, and we try to focus on
the things that science is asking right now, the questions
in the minds of scientists. We try to take you
to the cutting edge of current science and then do
obscurify it. We don't use complicated words like de obscurify.
We try to make things clear and understandable. You just
(03:28):
contradicted yourself there. I feel like we try to explain
things in the simplest way possible. When we explain it
are explaining, we use the most complicated words possible. Hey,
this is Daniel Jorge explained the universe, not Daniel Jorge
explained the explaining and then welcome through new podcast Daniel
and Jorge explain. Daniel and Jorge explain the universe. That's right,
the spinoff podcast exactly. I'm looking forward to that one.
(03:50):
A lot of TV shows now having like an aftershow,
So that's the better off solid podcasts. Yeah, let's talk
Daniel and Jorge podcast. Doesn't that need to have somebody
else on it though, where they can ridicule all of
our jokes. Yeah, let's pretend to be some other person. Oh,
there you go. I'll be David and you'll be Gearmo.
(04:12):
David and Jose. David Jose ridiculed Daniel and Jorge. Al right, well, yeah,
we talked about all the things scientists want to know
and um and how they look at the universe as well, right, Like,
you know, one way to look at the universe is
to compare it to the things around us. That's right,
and something we're always trying to do in sciences. Understand
(04:35):
our context is understand where we live, because hey, this
is our planet in our solar system. We'd like to
know is the rest of the of the universe similar
to what we're finding around us or is it totally different? Yeah,
because we like the Earth presumably, and it's pretty comfortable.
And I'm pro Earth. Your pro it's pretty I'm taking
a controversial opinion here at night, you're pro probably during
(04:58):
the day your entire Earth. Well, it's not like particle
physicists threatened to destroy the universe at any moment, so
on purpose, right, Hey, intentions matter. Okay, I'm sure they
matter once we're all made out of dissolved particles now.
But we want to understand the world around us, and
we want to understand if there are other worlds out there,
(05:18):
and we'd also just like to know is the thing
that we've been studying for the entire history of science
is it normal? Is it typical? Or are we studying
something which turns out to be really unusual and that
we can't generalize from to get sort of deeper truths
about the nature of the universe. Yeah, we like the Earth,
we like our solar system, but um is the rest
(05:39):
of the universe like us. And we're an amazing moment
in human history when we're for the first time really
getting glimpses for what the rest of the universe looked like.
You know, for thousands of years, all we could see
where other stars, but didn't even know if there were
other planets out there. And then fairly recently in human history,
thousands of years ago we discovered that there are other
planets out there. And now super recently, just like twenty
(06:00):
years ago, we've begun seeing planets around other stars. So
we can now ask and answer this question people have
been wondering about four thousands and thousands of years. So
today on the podcast, we'll be asking the question, is
our solar system weird or typical? And either way we
(06:23):
love it. Right, it's our solar system, whatever label you
put on it, we like it. But we're still curious.
Is it sort of the oddball solar system it's the
only one we've been studying for a long time, or
is it pretty typical? Yeah, this is a really cool question.
And because you know, I think we grew we grew
up in this solar system, right, and we don't have
we have no idea whether it's every other solar system
(06:46):
looks like this one, or whether we're like, it's really weird,
odd special gem or disaster, depending on how things work
out of a solar system. Yeah, and it's all we
could have studied for the long this time because our
telescopes couldn't see any further, so we were limited to
only looking at our cosmic neighborhood, to studying our planet
(07:07):
and the ones nearby, and so of course we were
curious what else was out there in the rest of
the universe. But imagine if you had only lived in
your hometown your whole life, and you never received any
news in the outside world, and so you didn't know
that people eight differently in other countries, and people went
to the bathroom differently in other countries, and dressed differently
and spoke differently. You imagined that everything else in the
(07:28):
world was sort of like your hometown. That's where we
are right now in science we're wondering if those other
solar systems are totally different or just the same as ours. Yeah,
you're saying humanity sort of like a like those mirror
cats you've seen documentaries. We were just finally sticking our
head out of the hole in the ground that we've
been living in and looking around this. Yeah, but we've
(07:49):
been desperate to do it for for a long time,
and we've only recently built a technology that's let us
see other solar systems and start to get an answer
to this question, because you know, I feel like most
people just assume that the rest of the universe looks
like our solar system and our planet, right Like, if
you look at most science fiction TV shows and movies,
you know, everywhere they go, it sort of looks suspiciously
(08:12):
like Earth. Yeah, And I think that's a failure of imagination,
especially on the part of science fiction. When you fly
to another planet and you know, hey, it has oxygen
on it and trees and hills and water that looks
just like ours, and oh, people on it that look
just like ours, but their foreheads are slightly wrinkly. I
think that's a failure of imagination. But it's also sort
of understandable because it's hard to imagine things totally different
(08:37):
from anything you've ever seen before. That's why good science
fiction is rare. Did you just insult All Star Trek
and Star Wars that was supposed to be sort of
like a subtweet? Didn't mention it by name, but yeah, yeah.
And so the question is are those science fiction movies right?
Are Are there really other earths out there? Are other
solar systems like ours? Or are we unique in this universe?
(08:59):
And so, as usual, we were wondering how what people
thought about this question, whether people thought that we are
unique or whether things are very different out there in
the verse. So I walk around campus and I asked
random students about other random solar systems. I think, for
a moment, do you think other solar systems look like ours?
Is our solar system typical or is our solar system
(09:21):
going to turn out to be really weird? The galactic oddball.
Here's what people had to say. From what I know,
it's typical. Um, I mean it depends what you say.
Typical is considering there billions of stars, but it's not unusual. No,
I have no idea. It's probably random. If there were
gases on a planet that were closer to the Sun
(09:43):
or like star, maybe they would like dissipate faster. I
think that it's ranks. I think you say I do
not know. I think it's random, and I think it's
going to be different Because our solar system it revolves
around the Sun. I think other systems are gonna be different.
So what do you think of those answers? Or pretty good?
I thought I felt like people had a strong opinion
(10:06):
about this topic. You know, everyone said I think it's X.
Nobody said I don't know or only one. Only a
few people said I had no idea, But a lot
of people that were like, I think I have an
opinion about this. Yeah, given that nobody really knows the
answer to this question, I was a little surprised at
the strength of people's opinions. I mean, I often ask
people questions and they go, I have no idea quantum what.
(10:28):
But this time people had an opinion. And maybe that's
just because people have thought about this. They've wondered what
other solar systems look like. They've thought about traveling to
the stars and walking on those planets and wondered if
they would be like ours. I wonder if you would
get different answers if you caveat each time you ask
these questions, If you caveat them with oh, and by
the way, some of the smartest people in the world
(10:49):
don't know the answer to this, I would be so
much less fun. Who would want to answer that? Nobody?
I love when people speculated. I of seeing them in
their minds sort of take this question on and sometimes
for the first time and formulate an answer. And my
favorite moments are when you can see somebody giving an
answer that sort of surprises themselves. They think about it,
(11:12):
they give an answer that, oh, I didn't realize I
do think that. That's fascinating. Makes me wonder how much
we actually think about the things we say. Sometimes I'm
just listening to my own self talking, I'm like, what
did he just say? So that's the question of the day.
Is is our solar system unique? Or is it pretty typical?
And if it's not typical, how different could it be
(11:34):
out there? And you should count yourself lucky to live
in a time when we will know the answer to
this question. Some of the greatest minds in history, Galileo Einstein, Newton,
even recent people like Richard Feynman, they looked up at
the stars and they wondered if other solar systems look
like ours. They all died not knowing the answer. All
you have to do is listen to this podcast. Yeah,
(11:55):
so you're welcome. Are you taking it for all the
scientific discoveries? Thank you? Or hey who personally built the
Hubble space telescope with his own hands? I signed the
back of it. I don't know if anyone will ever
you drew a doodle on it? Are you the official
cartoonist of the space telescope? Technically you can't prove that
I didn't sign the back of the Hubble telescope. Oh
(12:16):
I need another telescope trained on the space telescope to
see the back of it. I wonder if anybody ever
does that, But yeah, do you think so? Yeah, it's
an interesting question. I'm sure a lot of people have
asked before. So let's break it down for people, Daniel.
Let's talk about our solar system, and then let's talk
about what other solar system. Well, we know about other
solar systems out there, right, and our solar system is
(12:39):
actually quite fascinating because it has some sort of trends
in it. And you have to remember that all of
our knowledge of solar systems and how they're formed, all
of our theories how solar systems were built, have been
developed over decades or hundreds of years based on just
this one example, our solar system. So you know, we
sort of tuned these theories to describe what we've seen here,
(13:01):
and now comes the big test to see whether these
theories can be applied and explain other solar systems, right,
Because I think maybe people a lot of people don't
realize that we can't. Just up until very very recently,
and only just now barely, we haven't really been able
to like take a telescope pointing at another star and
see another solar system, right like it's up until very
(13:23):
very recently, it's been a complete mystery. What other solar
systems look like? Yeah, the first planet around another star
was seen just over twenty years ago, so it's a
blip in human history and even in scientific history. But
even before we talk about the other solar systems, our
solar system is interesting, like there are some weird trends
in it. You know, the first four planets in the
(13:43):
Solar System are all rocky planets. Planets basically come in
two flavors, rocky or gassy. It sounds like sounds like
a bad ice cream shop. Yeah, like like like what
happens when I like those into olm prison goes to
an ice cream shop? Yeah, well, the first four planets
have surfaces on them, right, You've got Mercury, Venus, Earth,
(14:04):
and Mars. These are basically balls of rock, rock and metal.
And so we call those rocky planets. And there's no
gas planets in the inner flour And said, you know
the four rocky planets, then you have the asteroid belt
that we dug into in a recent episode. And then
after the asteroid belt, you've got the gas giants and
the ice giants. You got Saturned, You've got Jupiter, you've
got Urinus and Neptune, and those are pretty different from
(14:26):
the inner planets. Is there a reason we don't have
liquid planets or like wet planets or like giant balls
of of a liquid floating around. Well, we can't have
liquid planets. In the far Solar System. We have basically
ice giants Uranus and Neptune. A huge fraction of them
is made of water, but it's frozen. Of course, it's
too cold out there. There is of course water here
on Earth. But could you have just like an entire
(14:47):
drop of water be a planet, that would be pretty amazing.
I think the pressure from it would probably crystallize the inside.
So basically become an ice planet with a ocean around it,
kind of like a Europa or what's what's the wound
that's like a giant ocean. Yeah, Europa has a huge,
actually thick crust of ice on top and then a
(15:08):
layer of water underneath, like an ocean underneath, and then
we don't know what's inside of that. So that's like
an eminem sort of. But as the reason we don't
have liquid planets, just just depending on the elements that
we have in our Solar system, I don't think you
can make a blob of of liquid water large enough
stay liquid because the core of it would just be
too dense. It would form a solid, like by the
(15:30):
time it got big enough to be called the planet,
would it would totally not be liquid. Yeah, the gravitational
pressure would make the inside of it become a solid
or or something more dense, so it wouldn't be liquid anymore.
Do you have this fantasy of swimming through like a
planet sized pool of water? The universe is biggest swimming pool.
That would be pretty cool, nothing but a huge drop
(15:51):
of water the size of the Earth and then a
single diving boards. You're like, you think you have an
infinity pool. I have a planet universe universe infinity pool.
But no, we don't have any liquid planets in our
solar system. But hey, maybe you know, we'll find planets
in other solar systems that are liquids and that will
prove us wrong, and maybe liquid planets are possible, but
(16:14):
we don't happen to have any in our solar systems.
That we have four rocky planets the asteroid belt and
then the gas giants and the ice giants. And you're saying,
that's kind of funny in that it's sort of like
a pattern, like it's four rocky asteroid belt gas giants.
It's not like rocky gas, rocky gas gas gas rocky. Yeah,
it doesn't seem random. Here's a question from a listener,
(16:36):
Camille who thought just the same thing. Hello, Danielle and Jey.
One of the recent episodes I have listened to your show,
which was all about the asteroid belt, you, daniel mentioned
that there must be a reason why we have solid
rocky planets before the asteroid belt and then only gas
giants afterwards. But you never got to answering this question,
(16:56):
is there a reason we know? Why? Is it like
this that we see these kind of pattern other stuff?
I'm dying to know. That's such a good point. Thank
you Camille for sending in that question. And every time
you see a pattern, you think maybe there's a reason
and you want to untangle that reason. Now, it's very
dangerous when you're drawing conclusions from one example. If you
(17:16):
visit somebody's house and they're like, oh, look, their family
is boy boy, boy, boy boy, girl, girl, girl, girl girl,
you're going to conclude there's a reason, right that they
all have younger girls and older boys. But if you're
only looking at one house, you're gonna be totally wrong.
That would be kind of impolite to ask Daniel. You're like,
did you guys try are you're doing something different? You
know when you um um, you know you'd be desperate
(17:39):
to know though, you'd be super curious. And also, there's
lots of families where it's like five boys and then
a girl, and you know that they were trying for
a girl and they finally got one and that's when
they stopped having kids. That's when they're like, we're a
closing shop. Yeah, so maybe our source systems close shops
after after Neptune or uranus. We're done trying to make
(18:00):
a liquid planet. It's not happening. We're sorry, we're trying
to make a giant swimming pool, but you know, it
just hasn't happened. That's right. The kid's gotta go swim
somewhere else. But so we do have some explanations we've
cooked up, but of course the proviso is, we don't
know if this works until we try to apply to
other solar systems. And the basic idea is that you
don't get gas giants close into the sun because the
(18:23):
Sun has all this radiation it spewing up the solar wind,
and that basically blows out all the light elements, the hydrogen,
the helium, all the stuff you need to make a
gas giant, all the gas. It blows it away from
the Sun. So that's why you don't have gas giants
close up to their star. It's kind of like a cloud.
It gets too close to the Sun, which is kind
of wish evaprate. Yeah, and so that's sort of the
(18:45):
explanation for why you have rocky planets close in. And
then in the outer planets it's colder, and so instead
of having liquid water, you have ice, and then that
ice helps the core of the planet's form. You're like,
you know, how does the planet form? Anyway, You the
initial sort of disc of stuff from the that formed
the whole Solar System, and some of it is spinning
so it doesn't fall into the star. And then in
(19:07):
the outer reaches, it's cold enough that you have ice
and that helps accumulate the gravity very slowly gather the
stuff together. Because you have ice out there, it can
sort of add ice to your basic planet core and
they can get big enough to suck up all the
gas and the hydrogen in the helium. Because remember hydrogen
helium is very light, which means it's hard to hold onto.
(19:28):
You need a huge gravitational mass to attract that. So
to make a gas giant, you have to form a
really big core of some metals and some ice in
order to pull in the rest of the gas. And
that can only happen in the outer reaches of the
solar system, where you have ice. And so the reason
you get gas giants and the outer Solar system is
because that's where the gas is and because that's where
(19:49):
the ice is to help pull those light gases together
into a gas giant. At least that's our theory, and
that's based on just what we've observed, all right. So
that explains why our solar system looks to wait us,
why it's like rocky in the middle and then gassie
out there in the edges of it. And so that's
kind of the picture of our solar system. We have
(20:10):
a yellow sun, some rocky planets, some asteroids, and then
giant gas balls um swirling around the edges of them, precisely.
And remember we've been aware of this for decades and
decades and decades and so we had a long time
to cook up this model based on just this one
solar system. It's become very fine tuned and and very
(20:31):
sort of baroque to explain exactly what we're seeing. And
so now comes the test. Now we get to apply
it to other solar systems and see if it also
explains what we see out there. Yeah, all right, so
let's get into what other solar systems look like. But
first let's take a quick break. All right, we're talking
(21:01):
about how our solar system may or may not be
different than other solar systems out there, and we know
that we have a pretty good picture you're saying, of
our solar system, and it's taken as a while, but
we can have a good idea of how our solar
system formed sort of and or white looks like rocky
planets and then gas giants. And so now the question
is is this what other solar systems look like like?
(21:23):
If I went to a nearby star, would I also
see you know, a similar sun, similar rocky planets in
the middle, and similar gas giants on the edges? Yea,
So maybe we should start from the center, right from
the star. That is, of course the easiest thing to see.
Our star is something we call a yellow dwarf, and
it turns out that even our kind of star is unusual.
(21:45):
Only like ten of the stars in our galaxy are
yellow dwarfs. The rest are something else we call a
red dwarf. And these names have to do with not
just like the size of the Sun, but also how
old the Sun is. Right, Yeah, they tell you something
where the Sun is in its life cycle. And there's
lots of different sort of paths that a sun can
take depending on how much mass it's started with. And
(22:08):
we had a whole episode about stellar evolution, and based
on the size that the Sun started with, they will
follow a certain path, And so the name of the
star tells you sort of which path it's on and
sort of how far along that path is. But most
of the stars in our galaxy are red dwarfs, which
mean that they're older than our Sun, and they're colder
and they're smaller. So if you want as much heat
(22:30):
that we as we feel on Earth, you'd have to
be closer to the star than you would be to ours.
So our sun is kind of is big for compared
to other stars in the universe, and it's also kind
of young, right, Like I think we're sort of like
in the teenage years of our shunt. It's big compared
to most of the stars in the galaxy. Of course,
there are other stars out there that totally dwarf it.
There these huge giants out there that are fantastically bigger
(22:54):
than our star, but they're unusual. Most of the stars
in the galaxy are smaller and colder and older than ours.
And ours is also different in another really fascinating way,
in that it's by itself. Our star doesn't have a
companion star. It's not like there's another star orbiting. It
turns out most stars actually formed together to like a
(23:14):
pair of stars. Right, So our son is all alone,
or or as uh Emma Watson would sage, where our
son is self partnered. Yea, our star is like the
runaway teenage star. It's all by itself in this lonely universe.
Of other stars in the universe are totally different than
our sun. Yeah. Yeah, so right there. If you want
(23:37):
to extrapolate from our solar system to others, you have
to be careful because most solar systems have a very
different kind of star. And that doesn't mean it's going
to be a completely different solar system where that it's
impossible to live there. But it means you want the
same amount of heat. For example, you have to be
closer up, so the Goldilocks zone for these stars is
smaller than it is for our star. The sun is colder,
(23:59):
and then you need to be closer to it to
be to have any life as we know it here
on Earth. Yeah, to have liquid water on the surface,
for example, which is basically what you need to have life,
we think life as we defined it. Right, Then they
need to be close enough to the star to get
enough radiation, and that would be closer to those smaller,
colder stars than ours. And so ninety percent of stars
(24:21):
are different out there, which means that if you are
in another planet, in another solar system, you know, ninety
percent of the time, it's not going to look like
it looks like you're it's not going to look like
a bright yellow you know son. Yeah, it would be
a little redder and a little colder. It sounds like
maybe in a lot of or most solar systems out there,
it would look like in Star Wars where they see
(24:43):
two sons in the horizon. Yeah, most of them have companions,
and those aren't necessarily super close together. Sometimes the companions
can be kind of far apart. But yeah, most stars
have another star pretty close by and they're orbiting each other.
But ours is by itself, and that's that's more unused
dual than typical. So already our star is unusual in
two ways, and that it's by itself, and that it's
(25:05):
a yellow dwarf. So already our solar system is is
pretty odd compared to the universe. Well, now, let's let's
talk about the Earth. Is a planet like Planet Earth,
the weird to have in a solar system out there?
Or is it pretty common? It turns out that the
most common planet to have in one of these solar
systems is not the Earth. It's something called a super Earth.
(25:26):
It's a rocky planet that's like ten or fifteen times
bigger than the Earth. And they categorize these planets in
other solar systems by giving them names relative to our planets,
like define the various categories. So like you have an
Earth planet or a super Earth up to you know,
ten or fifteen times the Earth. Anything bigger than that,
they call it like a mini Neptune. So that's the
(25:48):
names of these categories. And most solar systems have a
super Earth. It's the most common planet out there. Now,
you'll notice we don't have a super Earth. There's no
planet in our solar system that's a rocky planet that
it's like ten times the size of Earth. Is the
Earth the biggest rocky planet in our solar system? Yeah,
the Earth and Venus Venus is almost as big as
(26:08):
the Earth. Mars and Mercury are much smaller. And so
the Earth is the biggest rocky planet in our solar system.
But most solar systems you would find one that's like
ten or fifteen times bigger, bigger in terms of like
the radius or like the you know, there's the weight
of it. Yeah, ten times the mass, which doesn't quite
correspond to ten times the radius because you know, there's
some nonlinear effects there. But it's a lot more stuff, right,
(26:29):
So ten times as many rocks came together to form
a planet, and so we don't really know what that means.
This is something we've only recently figured out. We don't
know if that means that the distribution of rocks in
our solar system was different when it formed, or maybe
there was a super big planet, but it got broken up.
We don't really know. Is this just random that we
not unlucky, or is there some important reason for why
(26:51):
our solar system looks different in this important way. We
just don't know. So that if there are scientists on
those other earths, they would probably say that we live
in many Earth. Yeah, they would say, hey, look at
this weird solar system we found. It has only many
rocky planets. How cute. Look at those tiny little planets,
Baby Earth's look at those tiny little people with tiny heads.
(27:13):
Not only is our solar system weird in that that
our Sun is weird, but also our Earth is really weird.
So most earths out there are much much bigger. Yeah,
and some solar systems we found out there just have
more planets sort of tucked in close to the Sun.
Like we found this one solar system it's called the
Trappist System. It has seven planets within six million miles
(27:36):
of their sun. Remember, the Earth is like ninety million
miles from our Sun, So they have seven planets tucked
in like around the distance that Mercury is. Wow, just
spinning around like like crazy. Yeah, I'm just spinning around
like crazy. So most of the solar systems we've seen
have more planets close to the Sun than ours. Now,
(27:57):
this is hard to know. It might be that there's
a bias here because it's harder to see planets that
are far from the Sun because the way we observe them. Remember,
as we see planets like passing in front of the Sun,
and if a planet is going around the Sun every
hundred years, it just doesn't pass in front of the
Sun is often, so it's easier for us to see
planets that are close to their Sun. So it might
(28:19):
be that there's a bias that we're finding the weird
ones first. But they don't think so. They think they've
accounted for that effect and they think it's still real
that the average solar system out there has more planets
close to the Sun than ours. Interesting, so the average
solar system out there is busier, yeah, especially close in
like more I guess, more concentrated. It's like a traffic
(28:39):
jam every day, all day for the for for eternity literally. Yeah.
But on the other hand, it means it's not as
hard to get from planet to planet, like your neighboring
planet is more like a neighbor, you know, you could
jump from planet to planet. Wouldn't take hundreds of days
like it would take for us to get from Earth
to Mars. You could get to the next planet it
(29:00):
in you know, just a few days. Right, and maybe
even more dangerous to write, because all those planets that
close together, they some of them could crash into each other, right, yeah,
and they can also affect each other's orbits. Right, planets
are big, and remember these planets are not tiny things,
and so they can tweak each other's orbits. Theres lots
more weird gravitational interactions, and we've also seen that we've
(29:22):
seen that a lot of these solar systems have weird orbits.
Like in our Solar system, things are very neatly laid out,
like the planets are sort of equally spaced, and everything
is separated, and everything is mostly flat in a single
plane and pretty circular, though not completely. But other Solar
systems the orbits were seeing are really eccentric. They are
much less circular, some of them, Like there's one for example,
(29:45):
I looked up and it goes from being just a
few million miles of its from its star on one
side to two hundred million miles on the other, so
like it's super close and then whizzes out really far away, right,
Because orbits can be not just circular or oval shaped,
they can also be kind of off center from the Sun,
kind of like comets have these weird elliptical orbits that
(30:06):
are like go really far out and then come back
in really close, right. Yeah, And commets don't have to
be sort of on the plane of the planets. And
what we're seeing is that other solar systems don't always
have the same orderly plane, that the planets are all
all on different planes, and we don't know what that means.
We don't know, like is that typical and our solar
system is just kind of weirdly randomly well ordered, or
(30:27):
maybe something happened in those solar systems there were some
collisions because everything was so crowded in and they got
tugged and thrown off into weird orbits. We just don't know.
I feel like we're getting more and more into the
idea that maybe our solar system is really weird. It's
like we have a weird Sun and a weird Earth,
and a weird, weird arrangement of planets and a weird orbit.
(30:47):
It's like it's just right. Yeah, And we're like that
kid that went to school for the first time and
discovered that his family is really, really weird. Nobody else
eats peanut butter pickle sandwiches for lunch and dresses in
that weird way or whatever. And the other thing that
I found really fascinating is that, you know, in our
Solar system we have all the gas giants on the outside.
We thought we had an explanation for that, that the
(31:08):
gas was blown out by the solar wind. But in
other solar systems we find these planets we call hot jupiters,
big gas giants that are close to their stars, close
enough to be hot. Right, they're trending, that's right, exactly,
they're viral jupiters. No. But for example, there's a system
um I won't pronounce the name because it's just letters
(31:28):
and numbers, but there's a Jupiter sized planet that's so
close to its star at orbits every two days. What
it's whipping around the Sun every two days. Yeah, but
it's the size of Jupiter, and so people wonder, like,
how did this planet form? There's not enough gas in
our understanding in the center of the Solar system, to
form a gas giant. Right, the gas either fell into
(31:50):
the Sun to form the star or got blown out
by that star into the outer reaches of those solar systems. So,
how do you make a hot jupiter if it's just
a cloud of as when in it just kind of
you know, whipping around that fast wheed it just kind
of break apart or dissolver smear. But no, it's somehow
it's spinning around every two days. Yeah, and maybe it
has a really strong magnetic field which helps protected from
(32:13):
the solar radiation and the solar wind from blowing it apart.
We don't know. And one idea is that maybe it
did form on the outer reaches of that solar system,
but then sort of moved up, like bumped the other
planets out of the way to get closer to the Sun.
This could happen, right, Planets can change orders. Wow, So
you're basically saying that like our nice orderly solar system
(32:34):
with the rocky planets first and our gas giants out there,
is maybe not even typical either, Like that sort of arrangement.
You can have gas giants close to the Sun and
you could probably have rocky planets out there. Yeah, we've
seen hot jupiters. We've seen solar systems with gas giants
close to the Sun, and in some of these it
does look like maybe they did migrate in from the outside,
(32:57):
because we don't see like a lot of other inner
planets nearby. What would happen if Jupiter, for example, moved
in and tried to take over Venus orbit, well, Earth
and Mars and Venus and Mercury, we probably get tossed
out of the Solar system by Jupiter's gravity, And that's
what we see in these solar systems with a hot Jupiter.
We don't see a lot of other inner planets, so
we think maybe, you know, the big gas giant bully
(33:19):
came in and cleared out the playground, all right. So yeah,
there's a lot of ways in which our Solar system
is weird, right in terms of the Sun, the Earth,
and the gas giants. And so now let's talk about
UM some of the ideas that scientists have about whether
solar systems all formed the same way, or whether are
somehow made it into this special configuration for a special reason. First,
(33:42):
let's take a quick break a right, So let's talk
about um. What idea scientists have to explain all these
weird types of solar systems, like why is ours different?
(34:05):
How do other system solar systems form? What's the sort
of prevailing theory about how solar systems are made. Yeah,
So the theory we had for a long time before
we saw all these other solar systems, we call that
the core accretion theory, and it basically says, you start
from a big rotating blob of gas and dust and
some ice, and the star forms and the rest of
(34:25):
it you get you accrete the cores of these planets.
That just means that like the biggest rock that happens
to be out there gathers up other rocks around it,
and they form and they gather more stuff until you
get stuff big enough stuff to make a planet. And
that's how we explain how you get Jupiter. For example.
You're gathering together a bunch of rocks and ice and
that sucks up all the gas. Also, stuff was just
(34:46):
floating around and then they just because of gravity, just
formed into planets like condensation almost. And one the thing
that people have always wondered about that theory that they
didn't really like is that it takes a long time.
I mean gravity is really weak, and we're talking about
when you start, you're tugging on really small bits, you know,
bits of gas and bits of dust and tiny little pebbles.
(35:07):
So it's gonna take a long time to make Jupiter
out of bits of sand, right, And they worry that
it takes so long to form the core on this,
you know, the dust and the ice, that by then
all the gas will just have floated away or been
blown away by the solar wind. So there's always been
this bit of tension like how do you get these
planets to form soon enough that they can gather any
(35:27):
of that less leftover gas. So that's the old idea
and the sort of the concerns people have with it.
And now that we've seen these other solar systems, they're wondering, well,
maybe we need new ideas. And so there is a
new idea on the block. Oh I see, because this
idea that solar systems kind of form slowly might explain
may not even explain ours. But looking at other solar systems,
(35:49):
we're like, oh, whoa, whoa, we don't really have a
good idea about how solar systems form, because whatever we
come up with has to work for all of these
other solar systems. Yeah, and you know you need inspiration
in science, and this old idea was inspired by this
one example. Now that we've seen these other examples and
sort of stretches us in the right way to come
up with new ideas for how you could explain these examples.
(36:10):
And so one of these new ideas is called the
disc instability model. That idea is basically that when the
Solar system formed, you have this disc, but it wasn't
like a nice, calm, smooth disc that was slowly formed
from the rotating blob, but that there was still a
lot of sort of stuff going on. There's a lot
of action there, and that these instabilities is action inside
the disc might be a way to get these planets
(36:32):
to form sooner and also for them to form closer
to their stars. But what do you mean disc instability?
Like there's something extra special going on that makes Jupiters
and weird planets like that. Yeah. If the model you
have in your head is sort of like a giant,
stately cloud which is slowly rotating and then gradually gathering
together into a flat disc, that's the core creation model.
(36:54):
It assumes that everything is sort of very smoothly flowing.
But if instead it's a bit more turbulent, if this
is a little bit more chaos in there, you know,
it's more like a storm and it's being squeezed by
gravity a little bit, but there's still sort of stuff
going on inside of it. That's stuff that energy can
be used to sort of collide stuff together and make
and from those instabilities form gravitational course that can that
(37:16):
can gather stuff more rapidly. Oh, and that would explain
our solar systems or sort of all solar systems. Well,
it's not a very popular model yet and it's very fresh,
but it might explain how our solar system got gas
giants because it unless you form planets more rapidly. And
it also might explain how you were able to form
gas giants close to the star, because you could form
(37:38):
them quickly enough that you could form them before all
the gas was blown away by the Sun. But it's
still it's a very fresh model and it hasn't gained
wide acceptance yet, so it could be like maybe it's
just like the way solar systems form, is it just
this very chaotic process and sometimes you get solar systems
like ours and sometimes you get totally different solar systems. Yeah, precisely.
(38:00):
And the other idea is about planetary migration. People think
that maybe it's not unusual for planets to sort of
tug each other out of orbit and switch spots, you know,
to take each other's seats. And there's even the idea
that it could have happened in our Solar system. People
think that maybe. Yeah, people think that maybe Saturday and
Jupiter used to have an opposite order, and there was
(38:22):
another planet out there, a big ice giant, and the
three of them are sort of in this chaotic bumping
of each other, and they switched Saturn and Jupiter switched
and tossed the other planet sort of out to the
far reaches of the Solar System. And we just did
a whole episode about planet nine that could explain like
why planet nine is so far out there. So, yeah,
you're saying that even if you you form a solar system,
(38:44):
it can still change. You can still you can still
switch it around and change the structure of it, even
when it's sort of stable and floating along. Yeah, and
that means something interesting for our Solar system. It could
be in the future if you went away on a
spaceship for a billion years and came back, that you
could come back and find the Solar system looking quite different. Right,
Jupiter might have moved in on Mercury's territory and become
(39:06):
hot and tossed out all the other planets. We just
don't know. We don't know if this configuration is stable
on billions year time scales. That would be pretty cool
if you left for a few million years and then
came back and you're like, what happened to my house? Remodeled?
Just like everybody who goes away to college and comes
back after Thanksgiving and like, hey, everything looks different. You
turned my plan into a workout room. All right, Well,
(39:29):
it sounds like our solar system is not. It is weird,
that's the answer to the Today's question. It is kind
of weird in that you know, our son is single
and hot and young, and we apparently live in a
mini Earth, are not super Earth. And it's also weird
that we have all all of our gas giants out
(39:51):
there floating out there far away from the Sun. And
so it is because it sounds like it is sort
of a special case or solar system, like if we
go to other solar systems. We should be prepared to
see things that are very different. Yeah, and I'm so
glad that that's the answer. It would be so boring
if we discovered every solar system looked like ours, and
that the idea we have for how the solar system
(40:12):
formed was pretty much being on. It's exactly what you
hope for in science, that once you open up new
eyeballs or build bigger eyeballs, that you see surprises, that
you learn things, the things that shake up your ideas
for how our home and our solar system have been made.
And maybe it gives us a bit of a special
appreciation for this particular little cute many Earth we find
ourselves on. Yeah, maybe you'll go to another solar system
(40:34):
and everybody will have two pH d s. Should be
like what the Bruce Banner solar system? All right, Well,
we hope you the next time you think about your
planet or the solar system we're in, you sort of
think about how special it is and how weird it is,
and how unique it is out there in the universe.
And in five years or twenty years or fifty years,
(40:55):
we could find even more weird, surprising solar systems out
there that challenge our very concept of what the universe
looks like. Yeah, so stay tuned and keep funding science.
Thanks for tuning in, See you next time. Before you
still have a question after listening to all these explanations,
(41:18):
please drop us the line. We'd love to hear from you.
You can find us on Facebook, Twitter, and Instagram at
Daniel and Jorge That's one word, or email us at
Feedback at Daniel and Jorge dot com. Thanks for listening
and remember that Daniel and Jorge Explain the Universe is
a production of I Heart Radio. For more podcast from
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(41:42):
or wherever you listen to your favorite shows.