March 1, 2012 • 20 mins
Why do we never see the moon's backside? What would the Earth be like if one side always faced the sun? In this episode, Robert and Julie contemplate tidally locked planets and moons, where one side of the globe burns while the other freezes in darkness.
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Episode Transcript
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Speaker 1 (00:03):
Welcome to Stuff to Blow your Mind from how Stuff
Works dot com. Hey you welcome to Stuff to Blow
your Mind. My name is Robert Lamb and I'm Julie Douglas.
And today we're talking about tidle lock which is we're
discussing earlier sounds like it would have been like an
awesome lady surfers in prison movie from like mid nineties
(00:24):
cinematic tidal Lockdown. Yeah, title Lockdown. They were rebels on
the board and they paid dearly beneath the sea something
like that. Yeah, yeah, yeah, that's I like the ided
to mention that's an underwater prison. Yeah yeah, yeah, yeah,
it's wind so difficult to break out off. But now
we are not talking about that wonderful film idea. What
we are instead of talking about title locking in terms
(00:46):
of the way our planets and the ware Moon's gravitate
around other objects. Yeah, and how it actually affects the
planets um and the stars and the moon's And if
you think about the Moon and the Earth, for instance,
the moon is tidally locked to the Earth. We look
into the night sky and we always see the same
side of the moon, the same face, the same face
(01:08):
of the moon and the Moon's backside is always facing
away from us. Uh the dark side of the moon,
if you will, even though it's not technically dark all
the time because it gets sunlight as well, it's just
we never see it. It's it's tidally locked to us,
not to the Sun. If we were tidally locked to
the sun. Uh I, if an objects were titally locked
to the Sun, it would be a different scenario where
(01:29):
only one side of the planet would receive sunlight and
the other side would be cast in perpetual darkness. Yeah,
but for us, this is a very stable arrangement right
right as having the moon tidally locked to us and
the man the moon just bean that that same face
that we see every night, and presumably his his hind
quarters on the other side. Yeah. The Moon, of course
is rotating like it's It's important to note it's not
(01:51):
that the moon is motionless up there, but it completes
one rotation about its axis in the same time it
takes to complete one orbit around the Earth. So it's
it's just lined up perfectly. It's there's a synchronicity and
in the way these these worlds are moving and meanwhile
we're just you know, turning to run our access going
hey son and getting day and night right right, And
the title inners it because the synchronization is caused by
(02:13):
strong tidal forces from the Earth that effectively lock the
moon's orientation. And it's really interesting to know that it
wasn't always like this. The rotation has sort of set
in over time, which I think is pretty fascinating. That's right.
The gravitational poll has has changed the rate of the speed,
I should say, of our rotation. But this has happened
over millions and millions and millions. Yea. And there of
(02:35):
course other moons that have a similar situation going, and
you see a lot with moons. If we look all
the way to the edge of our solar system to
the Planetoi Pluto, you'll find that it has a little
moon called sharone Um or Sharon, however you want to
say it. My Dante teacher always such Sharon. Yeah, Salva Maria.
If anyone anyone at Tense University of tennessee Knox Fall
(02:57):
and wants a good Italian Dante teacher, h check up
old Steal anyway, So Sharon's or a bit around Pluto
takes six point for earth days and one Pluto rotation
takes six point four earth days. What's interesting here is
that sharone neither rises nor sets, but basically hovers over
the same spot on Pluto's surface all the time. So
(03:17):
it's like a really extreme example of tidal locking. Yeah,
and this again happens with moons, but it also is
very common that it happens with stars as well, red
dwarf stars most commonly. So a planet gets locked into
or rather I should say, yes, the planet gets locked
into the star's orientation, and that changes everything for the planet, right,
(03:38):
because if you are just facing one side of the sun,
you would never experience day and night like we do.
One side would constantly be in darkness while the other
side would constantly be in light. There are various old
folk tales where like they'll be like a maiden whose
task with a job like she has to before the
sun comes up, she has to finish knitting a scar
for ori. Generally it's something a little more complex, like
(04:00):
draining an entire pond with a straw or a spoon
or something that sounds just like those old folk tales are. Yeah,
it's always some ridiculous task. And then like a good
fairiy or something will come along and turn back the clock.
In real life, there would be just catastrophic consequences because
the cycle of night and day is vital to the
way our weather works, but the way that the Earth
(04:21):
as we experience it works. I mean you have one side,
you have daylight regions heating up, you have night regions
cooling down, you have airflow moving back and forth. I mean,
it's all part of the system. There's an article on
house the work's called How Weather Works that I happen
to write. But it is a good job of taking
some of the very simple elements of night and day
and using that as a starting point for understanding how
(04:43):
global weather operates well and also how it affects every
living organism. Right, And we take that for granted sometimes
because of course the sun rises in the sunsets um
and we we live and die by this configuration. But
you know, they're they're of at the other configurations going
on in the universe. And the question is what does
(05:06):
this look like? And if you did have this sort
of configuration where it was only day only night on
one half of the planet, would there be opportunities for life?
Would organisms have a habitable area, and so that's what
we're going to talk about a little bit more in depth. Um,
(05:26):
you know, what, what does the weather look like? You know?
My mind immediately turned to science fiction, so I I
was looking up to see what other examples I could
think of that were sci fi related. If anyone out
there knows of a good example of a tidally locked
world in science fiction where they actually explore weather and
some of the more realistic effects, I would love to
hear about them, because the main examples would come to
(05:47):
my mind, or things like there's the nineteen twelve novel
The Night Land by William Hope Hodgson, which I'm pretty
sure I've mentioned here before. This is the early post
apocalyptic book that is so filled with this fantastic, wonderful
ark ideas, but it's written so tiresomely, so badly, that
it's you're just constantly sifting for these nuggets of gold
(06:10):
amid just utter crap. It has its lovers, and I
have kind of I have a very much of love
hate relationship with this book. But it takes place in
a world where the sun is burned out and the
remnants of humanity retreat into these massive geothermal powered pyramids,
and they grow crop crops and subterranean chambers, and they're
telepaths and they're spinning disc weapons all you know, monsters
(06:32):
out in the dark and all. But what's really cool
about it is that Hodgson's fiction was based on Lord
Kelvin's theories of the way gravity works. So the night
land in the scenario this whole plant is the world
again where the sun has going going dark and title
Dragon slow the earth rotation to a crawl. He depicts
this world is one where you have an entire just
frozen night side of the world and then this dying
(06:53):
side of the world that's facing a sun that's fading out.
Another example that comes to mind is Jack of Shadows
by Roger zelaz Name. This is a pretty fabulous little
novel that has a that has a lot of magic
in it. So it's not really you know, like I say,
he's not really concerned with weather patterns. But there's a
side of that. It's a tidally locked world. There's a
night world and then there's a day world. The day
world is ruled by science and technology, in the night
(07:15):
world is ruled by magic. And you have a character
who's from the night world and every time he dies
in the daylight world, he's he's reborn on the far
side and dreams. Yeah. Uh. And then and of course
that we have to look at Star Trek. There are
a few different planets that pop up there, but the
most notable seems to be the planet Remus, which is
(07:36):
the third of four planets in the Romulan system. And
you have a situation here where it's basically a mining world,
and you have a race of individuals called the Riemans.
It's playing on the whole Remus and Romulus. You know,
the Riemans are either a separate species that evolve on
the dark side of the planet, or they're sort of
like the early Romulan setters who have devolved or evolved
(07:59):
into nighttime species, so they look like kind of big
bat creatures. They've evolved to live in this dark portion
of this tidally locked world. Well see, and that's what
that's why our imagination can't help but go wild with this,
because when you start to think about tidally locked world,
you start to think about, you know, some sort of
organism that may I'm not saying that they're there are
(08:19):
bad people um. But but obviously there are adaptations that
nature makes, and so you start to wonder what that
would look like. But before you can even start to
look at that, you have to really start to think
about what this planet would feel like, um, what sort
of weather systems. Obviously, there would be no seasons, right.
The only change in the amount of sunlight would come
(08:40):
from the slight variation and distance from the Sun because
of the like for instance, if if Earth were to
become locked to the Sun UM because the Earth's orbit
being slightly out of round. So if that were to
happen with the Earth, then you'd have slight variations. There
might be different climate depending on how far away you
are from the center of the side that always faces
(09:01):
the sun UM. On the equator of the sun facing side,
you'd have like these incredibly high temperatures, and in the
center of land masses that are facing the sun, you'd
have hot as haitise deserts. Right. And then by the coast, okay,
there would be an incredible amount of thunderstorms because of
the rapid evaporation of water. So yes, their water could
(09:24):
exist in some of these scenarios, and there have been
tons of computer models that have told us there's an
opportunity for atmosphere to die off, to completely evaporate, right,
or it could sustain itself in this continuous cycle where
if you have thunderstorms depositing weather systems of rain over
to the dark side. I love to think of this
(09:45):
dark side is sort of a snow globe effect. You
know that it's constantly you know, snowing over there or
raining over there, and uh, and then again the cycle
just continues on. Yeah, and then like you said, there
are other models of it that should there being very
little person to station on the night side, because you
end up with the substantial precipitation at the what it's
called the subsolar point, the point where the sun is
(10:08):
baking the earth the most though, like the dead on
sun zone, and then you have net evaporation, and so
you have all the the atmospheric water is transported from
the night side of the day side. You eventually have
oceans just freezing on the other side of the world. Right.
So it takes a little time because you also they're
also those oceans are growing saltier due to the evaporation,
and there you know, it's still a system of water
(10:30):
that's very much and flows, so it takes longer for
it to to freeze up. Yeah, and so you would
have all these different circles of climates. Basically, it wouldn't
just be like, oh, this one half of of you
know on Earth that had become locked to the Sun
was completely hot boiling and the other half was frozen zero.
I mean, there would be variations in between. And that's
the really exciting thing about whether or not um there
(10:52):
would be habitable zones that could support life, right, And
this is very much a question when we're looking at
these exoplanets, because we're catching the planets in the habitable zone,
but there's a little there's a certain amount of crossover
between habitable zone planets and potentially tidally locked planets, especially
when it comes to in the stars, which are stars
that are slightly bigger than the one that we call Sun.
(11:14):
It would be one of those situations where you'd be like,
all right, the planets in the right spot. It's in
that Goldilocks zone where it's just the right size where
it could conceivably have life. Oh, but it's not rotating.
So it's kind of like the house looks great, but
there's no power you know, it's uh, there's something drastically
wrong here. Alright, we're gonna take a quick break and
then we're gonna get back to all this. So hanging
(11:34):
there for one sec. All right, we're back now. Astrobiologists
think there might be some situations to where you would
have a certain amount of what's called substellar weathering instability
occur where basically you have higher temperatures that resulting in
stronger rainfall, and those the rainfall is weathering away the soil,
(11:55):
exposing more and more minerals, which then react with the
chemicals in the air into a certain extent that could
be counteracted by volcanic activity on the planet. So there
might be a situation where tidily locked world would be
balanced out a bit and you would have this habitable
zone on the world. Generally, it would be that that
ring that sort of exists as a borderland between the
(12:15):
night land and then in the dayland, right, Which is
that That's the part that I just get so excited
about because I think where there's there's the opportunity for
for life existing. And it kind of made me think
about when we were talking about star dust though, about
how difficult it is to build up life on a planet,
and you just have you have to have the absolute
(12:36):
right conditions and the right building blocks. So I mean,
you know, remember that life evolved on Earth for two
billion years before it began to produce and use oxygen,
for instance, and organisms used photosynthesis, which use carbon dioxide,
and all those little guys produce little puffs of oxygen
and over millions and millions of years, created more and
(12:57):
more oxygen and what is now our atmosp fhere, right,
So you know, we talked about this and we say
there could be habitable zones, but again, all these elements
have to be just right, yeah, and the only model
for life that we have is very much a rotating planet.
It's it is not tidally locked. So it becomes even
more difficult to try imagine how that process might take
(13:19):
place on a world where you have just a night world,
a day world and then this potentially happenable twilight zone
ringing around them right, right, and you'd have to have
an atmosphere, right, So that's that's the first thing again though,
there there's this opportunity to have the atmosphere, as you said,
if you've got enough going on day and night side
(13:40):
that they sort of converge to have these habitable zones
that could support um, you know, an atmosphere and keep
it in. Yeah, and what's interesting to there's some models
for tidally locked worlds where it's not it's not like
a perfect tidal lock, where they'll be the two rotations
don't completely line up, so they'll be like a little
bit of wiggle room there. You could potentially have a
(14:01):
world where there would be regions that would sort of
have a little night and day going on in that
habitable ring. Well, and a lot of people have thought
about this, particularly in terms of Earth, like whatever, Earth
became totally locked to the Sun because Mercury, it's thought
was once tinally locked. Um Radar observations of Mercury revealed
(14:21):
that the planet rotates three times on its access for
every two orbits yea. Early on, we actually thought it
was titlely locked like the n Yeah. The thing is,
because of the planet's tiny size and the proximity to
the Sun, it makes it a really good candidate for
being tital a locked. So here's the thing though, They
think that this this weird sort of rotation system that
(14:42):
has going on is the result of a giant impact
from the asteroid that knocked Mercury once it was totally
locked um into what is now sort of odd rotation configuration. Yeah,
it's got a massive hole in it called Rambat Crater,
which is about a seven and fifty kilometers wide. Would
is pretty substantial for a planet that's under five thousand
(15:03):
kilometers in size. Yeah, and they said that asteroid would
have been about forty three miles wide and about fifty
trillion metric tons in mass. So can you imagine this
object hurling into Mercury tile a locked world and actually
changing not just the spin but the but it even
being locked. Yeah, there's there's a theory that this planet
(15:25):
size impact may have also had an effect on the
density of the planet because it is an extremely dense world.
And there are a number of theories as the wine
that may be, but one of them is that this
enormous impact may have knocked it round. Here's here's what
I want to get to is that the what effs? Right?
And I immediately start thinking how you've got this perpetual
night and my mind goes to cave fish. Yes, because
(15:48):
kfish are a great example of something that has adapted
to its environment. Cavefish are indigenous to Somalium, and they
have been cut off from the sun for up to
two point six million years and they lived in dark
caves under the Smilean dessert for millions of years um.
And then they had lost their eyes and scales and
(16:09):
their coloring. And now researchers think that they're they're actually
losing their their internal body clocks. What is fascinating about
that is that it's taken that long for their internal
clocks to kind of get off a bit. Wow, So
that's the pace in which these changes occur. Really, yeah,
I mean, you know, the obviously their their physical changes occurred,
(16:31):
you know, much faster than that. So if you can
imagine humans, if this were to happen to the Earth
right for some reason, uh, you know, our eyes kind
of scaling over with skin uh and then you know,
our pigment changing, but still even two point six million
years after the event, having some sort of pull towards this,
you know, dining in old World even though you're in
(16:53):
perpetual darkness because their entire evolutionary history hinges on it.
Even if we ended up becoming some sort of more
lock or or like the creatures in the descent, you know, yeah,
so I mean if you were sun deprived, can you
can you imagine the sort of traditions and metaphors that
would arise in language if you if you are sun
starved and still dependent on it and yet you had
(17:13):
adapted in some ways. Yeah, of course, there would be
a lot of questions as to how you were obtaining food,
and because as we've explored the the situation on the
dark side of the world would be pretty grim. I mean,
there's no there's no light, so photosynthesis is coming to
a close. Um, you have freezing temperatures, you have moisture
being drawn to the other side of the world. So
(17:35):
it's it's hard to imagine what life would consist of
in that situation unless you you did have a scenario
where individuals were somehow technologically sustained, or if there was
some sort of trade situation with the with the daylit world.
But but things are gonna be pretty severe there too,
so I guess it would be more like you would
have to have some sort of trade scenario with the
twilight world, like that's the that's the area where civilization
(17:58):
is going to thrive more because you can have the
baked side and the frozen side and only in the
middle of things going to be just right right. And
of course we're talking about you know, if this were
to occur on the Earth, this is not something that
would happen like the next dayking about millions of millions. Yeah, yeah, yeah, right,
but you know, I mean, you'd have life forms that
could not subsist on the on the sunlit side, and
(18:19):
by some versa, well you've seen what happens to say,
like the neighborhoods in Atlanta when when there's a severe
snowstorm like two weeks and it's full on cannibalism and
road warriors in the street. Yeah, Atlanta would not farewell, Yeah,
with this situation at all. But the heat side conscious
sign we could. We could probably roll with that pretty
much what we do in the summer anymore. Yeah, you're right, right,
(18:41):
I mean, actually like eight months of a year. Yeah,
you hear us Florida, you hear us Alabama. All right,
So tell us what you think about all that. Do
you have any thoughts on a tidally locked world? You
have some other great examples from science fiction you would
like to do or fantasy you would like to share
with us. There is I mean, there's a whole wonderful
sub genre of to see zi fi with the dying
(19:02):
art scenario where you have the sun dying, and I
think I did a blog post about that a while back.
It's the fascinating zone of imagination. But I have not
encountered much in the way of tidily locked world. So
send me some examples. I would especially again love to
hear examples that take weather into account. Yeah, especially if
if you've ever come across, uh, some sort of idea
(19:23):
of an extra planet with half of the planet being
a snow globe. Yeah, that's that's That's all I'm interested in, really,
the snow globe part of it. Snow global girl. Yeah
all right. Well, hey, if you want to share it
with us, you can find us on Facebook. You can
find us on Twitter. On Facebook, we are stuff to
Blow the Mind and on Twitter. Our Twitter handle is
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line at Blow the Mind at Discovery dot com. Be
(19:51):
sure to check out our new video podcast, Stuff from
the Future. Join how stuf work staff as we explore
the most promising and perplexing possibilities of tomorrow. Three
Welcome to Stuff to Blow your Mind from how Stuff
Works dot com. Hey you welcome to Stuff to Blow
your Mind. My name is Robert Lamb and I'm Julie Douglas.
And today we're talking about tidle lock which is we're
discussing earlier sounds like it would have been like an
awesome lady surfers in prison movie from like mid nineties
(00:24):
cinematic tidal Lockdown. Yeah, title Lockdown. They were rebels on
the board and they paid dearly beneath the sea something
like that. Yeah, yeah, yeah, that's I like the ided
to mention that's an underwater prison. Yeah yeah, yeah, yeah,
it's wind so difficult to break out off. But now
we are not talking about that wonderful film idea. What
we are instead of talking about title locking in terms
(00:46):
of the way our planets and the ware Moon's gravitate
around other objects. Yeah, and how it actually affects the
planets um and the stars and the moon's And if
you think about the Moon and the Earth, for instance,
the moon is tidally locked to the Earth. We look
into the night sky and we always see the same
side of the moon, the same face, the same face
(01:08):
of the moon and the Moon's backside is always facing
away from us. Uh the dark side of the moon,
if you will, even though it's not technically dark all
the time because it gets sunlight as well, it's just
we never see it. It's it's tidally locked to us,
not to the Sun. If we were tidally locked to
the sun. Uh I, if an objects were titally locked
to the Sun, it would be a different scenario where
(01:29):
only one side of the planet would receive sunlight and
the other side would be cast in perpetual darkness. Yeah,
but for us, this is a very stable arrangement right
right as having the moon tidally locked to us and
the man the moon just bean that that same face
that we see every night, and presumably his his hind
quarters on the other side. Yeah. The Moon, of course
is rotating like it's It's important to note it's not
(01:51):
that the moon is motionless up there, but it completes
one rotation about its axis in the same time it
takes to complete one orbit around the Earth. So it's
it's just lined up perfectly. It's there's a synchronicity and
in the way these these worlds are moving and meanwhile
we're just you know, turning to run our access going
hey son and getting day and night right right, And
the title inners it because the synchronization is caused by
(02:13):
strong tidal forces from the Earth that effectively lock the
moon's orientation. And it's really interesting to know that it
wasn't always like this. The rotation has sort of set
in over time, which I think is pretty fascinating. That's right.
The gravitational poll has has changed the rate of the speed,
I should say, of our rotation. But this has happened
over millions and millions and millions. Yea. And there of
(02:35):
course other moons that have a similar situation going, and
you see a lot with moons. If we look all
the way to the edge of our solar system to
the Planetoi Pluto, you'll find that it has a little
moon called sharone Um or Sharon, however you want to
say it. My Dante teacher always such Sharon. Yeah, Salva Maria.
If anyone anyone at Tense University of tennessee Knox Fall
(02:57):
and wants a good Italian Dante teacher, h check up
old Steal anyway, So Sharon's or a bit around Pluto
takes six point for earth days and one Pluto rotation
takes six point four earth days. What's interesting here is
that sharone neither rises nor sets, but basically hovers over
the same spot on Pluto's surface all the time. So
(03:17):
it's like a really extreme example of tidal locking. Yeah,
and this again happens with moons, but it also is
very common that it happens with stars as well, red
dwarf stars most commonly. So a planet gets locked into
or rather I should say, yes, the planet gets locked
into the star's orientation, and that changes everything for the planet, right,
(03:38):
because if you are just facing one side of the sun,
you would never experience day and night like we do.
One side would constantly be in darkness while the other
side would constantly be in light. There are various old
folk tales where like they'll be like a maiden whose
task with a job like she has to before the
sun comes up, she has to finish knitting a scar
for ori. Generally it's something a little more complex, like
(04:00):
draining an entire pond with a straw or a spoon
or something that sounds just like those old folk tales are. Yeah,
it's always some ridiculous task. And then like a good
fairiy or something will come along and turn back the clock.
In real life, there would be just catastrophic consequences because
the cycle of night and day is vital to the
way our weather works, but the way that the Earth
(04:21):
as we experience it works. I mean you have one side,
you have daylight regions heating up, you have night regions
cooling down, you have airflow moving back and forth. I mean,
it's all part of the system. There's an article on
house the work's called How Weather Works that I happen
to write. But it is a good job of taking
some of the very simple elements of night and day
and using that as a starting point for understanding how
(04:43):
global weather operates well and also how it affects every
living organism. Right, And we take that for granted sometimes
because of course the sun rises in the sunsets um
and we we live and die by this configuration. But
you know, they're they're of at the other configurations going
on in the universe. And the question is what does
(05:06):
this look like? And if you did have this sort
of configuration where it was only day only night on
one half of the planet, would there be opportunities for life?
Would organisms have a habitable area, and so that's what
we're going to talk about a little bit more in depth. Um,
(05:26):
you know, what, what does the weather look like? You know?
My mind immediately turned to science fiction, so I I
was looking up to see what other examples I could
think of that were sci fi related. If anyone out
there knows of a good example of a tidally locked
world in science fiction where they actually explore weather and
some of the more realistic effects, I would love to
hear about them, because the main examples would come to
(05:47):
my mind, or things like there's the nineteen twelve novel
The Night Land by William Hope Hodgson, which I'm pretty
sure I've mentioned here before. This is the early post
apocalyptic book that is so filled with this fantastic, wonderful
ark ideas, but it's written so tiresomely, so badly, that
it's you're just constantly sifting for these nuggets of gold
(06:10):
amid just utter crap. It has its lovers, and I
have kind of I have a very much of love
hate relationship with this book. But it takes place in
a world where the sun is burned out and the
remnants of humanity retreat into these massive geothermal powered pyramids,
and they grow crop crops and subterranean chambers, and they're
telepaths and they're spinning disc weapons all you know, monsters
(06:32):
out in the dark and all. But what's really cool
about it is that Hodgson's fiction was based on Lord
Kelvin's theories of the way gravity works. So the night
land in the scenario this whole plant is the world
again where the sun has going going dark and title
Dragon slow the earth rotation to a crawl. He depicts
this world is one where you have an entire just
frozen night side of the world and then this dying
(06:53):
side of the world that's facing a sun that's fading out.
Another example that comes to mind is Jack of Shadows
by Roger zelaz Name. This is a pretty fabulous little
novel that has a that has a lot of magic
in it. So it's not really you know, like I say,
he's not really concerned with weather patterns. But there's a
side of that. It's a tidally locked world. There's a
night world and then there's a day world. The day
world is ruled by science and technology, in the night
(07:15):
world is ruled by magic. And you have a character
who's from the night world and every time he dies
in the daylight world, he's he's reborn on the far
side and dreams. Yeah. Uh. And then and of course
that we have to look at Star Trek. There are
a few different planets that pop up there, but the
most notable seems to be the planet Remus, which is
(07:36):
the third of four planets in the Romulan system. And
you have a situation here where it's basically a mining world,
and you have a race of individuals called the Riemans.
It's playing on the whole Remus and Romulus. You know,
the Riemans are either a separate species that evolve on
the dark side of the planet, or they're sort of
like the early Romulan setters who have devolved or evolved
(07:59):
into nighttime species, so they look like kind of big
bat creatures. They've evolved to live in this dark portion
of this tidally locked world. Well see, and that's what
that's why our imagination can't help but go wild with this,
because when you start to think about tidally locked world,
you start to think about, you know, some sort of
organism that may I'm not saying that they're there are
(08:19):
bad people um. But but obviously there are adaptations that
nature makes, and so you start to wonder what that
would look like. But before you can even start to
look at that, you have to really start to think
about what this planet would feel like, um, what sort
of weather systems. Obviously, there would be no seasons, right.
The only change in the amount of sunlight would come
(08:40):
from the slight variation and distance from the Sun because
of the like for instance, if if Earth were to
become locked to the Sun UM because the Earth's orbit
being slightly out of round. So if that were to
happen with the Earth, then you'd have slight variations. There
might be different climate depending on how far away you
are from the center of the side that always faces
(09:01):
the sun UM. On the equator of the sun facing side,
you'd have like these incredibly high temperatures, and in the
center of land masses that are facing the sun, you'd
have hot as haitise deserts. Right. And then by the coast, okay,
there would be an incredible amount of thunderstorms because of
the rapid evaporation of water. So yes, their water could
(09:24):
exist in some of these scenarios, and there have been
tons of computer models that have told us there's an
opportunity for atmosphere to die off, to completely evaporate, right,
or it could sustain itself in this continuous cycle where
if you have thunderstorms depositing weather systems of rain over
to the dark side. I love to think of this
(09:45):
dark side is sort of a snow globe effect. You
know that it's constantly you know, snowing over there or
raining over there, and uh, and then again the cycle
just continues on. Yeah, and then like you said, there
are other models of it that should there being very
little person to station on the night side, because you
end up with the substantial precipitation at the what it's
called the subsolar point, the point where the sun is
(10:08):
baking the earth the most though, like the dead on
sun zone, and then you have net evaporation, and so
you have all the the atmospheric water is transported from
the night side of the day side. You eventually have
oceans just freezing on the other side of the world. Right.
So it takes a little time because you also they're
also those oceans are growing saltier due to the evaporation,
and there you know, it's still a system of water
(10:30):
that's very much and flows, so it takes longer for
it to to freeze up. Yeah, and so you would
have all these different circles of climates. Basically, it wouldn't
just be like, oh, this one half of of you
know on Earth that had become locked to the Sun
was completely hot boiling and the other half was frozen zero.
I mean, there would be variations in between. And that's
the really exciting thing about whether or not um there
(10:52):
would be habitable zones that could support life, right, And
this is very much a question when we're looking at
these exoplanets, because we're catching the planets in the habitable zone,
but there's a little there's a certain amount of crossover
between habitable zone planets and potentially tidally locked planets, especially
when it comes to in the stars, which are stars
that are slightly bigger than the one that we call Sun.
(11:14):
It would be one of those situations where you'd be like,
all right, the planets in the right spot. It's in
that Goldilocks zone where it's just the right size where
it could conceivably have life. Oh, but it's not rotating.
So it's kind of like the house looks great, but
there's no power you know, it's uh, there's something drastically
wrong here. Alright, we're gonna take a quick break and
then we're gonna get back to all this. So hanging
(11:34):
there for one sec. All right, we're back now. Astrobiologists
think there might be some situations to where you would
have a certain amount of what's called substellar weathering instability
occur where basically you have higher temperatures that resulting in
stronger rainfall, and those the rainfall is weathering away the soil,
(11:55):
exposing more and more minerals, which then react with the
chemicals in the air into a certain extent that could
be counteracted by volcanic activity on the planet. So there
might be a situation where tidily locked world would be
balanced out a bit and you would have this habitable
zone on the world. Generally, it would be that that
ring that sort of exists as a borderland between the
(12:15):
night land and then in the dayland, right, Which is
that That's the part that I just get so excited
about because I think where there's there's the opportunity for
for life existing. And it kind of made me think
about when we were talking about star dust though, about
how difficult it is to build up life on a planet,
and you just have you have to have the absolute
(12:36):
right conditions and the right building blocks. So I mean,
you know, remember that life evolved on Earth for two
billion years before it began to produce and use oxygen,
for instance, and organisms used photosynthesis, which use carbon dioxide,
and all those little guys produce little puffs of oxygen
and over millions and millions of years, created more and
(12:57):
more oxygen and what is now our atmosp fhere, right,
So you know, we talked about this and we say
there could be habitable zones, but again, all these elements
have to be just right, yeah, and the only model
for life that we have is very much a rotating planet.
It's it is not tidally locked. So it becomes even
more difficult to try imagine how that process might take
(13:19):
place on a world where you have just a night world,
a day world and then this potentially happenable twilight zone
ringing around them right, right, and you'd have to have
an atmosphere, right, So that's that's the first thing again though,
there there's this opportunity to have the atmosphere, as you said,
if you've got enough going on day and night side
(13:40):
that they sort of converge to have these habitable zones
that could support um, you know, an atmosphere and keep
it in. Yeah, and what's interesting to there's some models
for tidally locked worlds where it's not it's not like
a perfect tidal lock, where they'll be the two rotations
don't completely line up, so they'll be like a little
bit of wiggle room there. You could potentially have a
(14:01):
world where there would be regions that would sort of
have a little night and day going on in that
habitable ring. Well, and a lot of people have thought
about this, particularly in terms of Earth, like whatever, Earth
became totally locked to the Sun because Mercury, it's thought
was once tinally locked. Um Radar observations of Mercury revealed
(14:21):
that the planet rotates three times on its access for
every two orbits yea. Early on, we actually thought it
was titlely locked like the n Yeah. The thing is,
because of the planet's tiny size and the proximity to
the Sun, it makes it a really good candidate for
being tital a locked. So here's the thing though, They
think that this this weird sort of rotation system that
(14:42):
has going on is the result of a giant impact
from the asteroid that knocked Mercury once it was totally
locked um into what is now sort of odd rotation configuration. Yeah,
it's got a massive hole in it called Rambat Crater,
which is about a seven and fifty kilometers wide. Would
is pretty substantial for a planet that's under five thousand
(15:03):
kilometers in size. Yeah, and they said that asteroid would
have been about forty three miles wide and about fifty
trillion metric tons in mass. So can you imagine this
object hurling into Mercury tile a locked world and actually
changing not just the spin but the but it even
being locked. Yeah, there's there's a theory that this planet
(15:25):
size impact may have also had an effect on the
density of the planet because it is an extremely dense world.
And there are a number of theories as the wine
that may be, but one of them is that this
enormous impact may have knocked it round. Here's here's what
I want to get to is that the what effs? Right?
And I immediately start thinking how you've got this perpetual
night and my mind goes to cave fish. Yes, because
(15:48):
kfish are a great example of something that has adapted
to its environment. Cavefish are indigenous to Somalium, and they
have been cut off from the sun for up to
two point six million years and they lived in dark
caves under the Smilean dessert for millions of years um.
And then they had lost their eyes and scales and
(16:09):
their coloring. And now researchers think that they're they're actually
losing their their internal body clocks. What is fascinating about
that is that it's taken that long for their internal
clocks to kind of get off a bit. Wow, So
that's the pace in which these changes occur. Really, yeah,
I mean, you know, the obviously their their physical changes occurred,
(16:31):
you know, much faster than that. So if you can
imagine humans, if this were to happen to the Earth
right for some reason, uh, you know, our eyes kind
of scaling over with skin uh and then you know,
our pigment changing, but still even two point six million
years after the event, having some sort of pull towards this,
you know, dining in old World even though you're in
(16:53):
perpetual darkness because their entire evolutionary history hinges on it.
Even if we ended up becoming some sort of more
lock or or like the creatures in the descent, you know, yeah,
so I mean if you were sun deprived, can you
can you imagine the sort of traditions and metaphors that
would arise in language if you if you are sun
starved and still dependent on it and yet you had
(17:13):
adapted in some ways. Yeah, of course, there would be
a lot of questions as to how you were obtaining food,
and because as we've explored the the situation on the
dark side of the world would be pretty grim. I mean,
there's no there's no light, so photosynthesis is coming to
a close. Um, you have freezing temperatures, you have moisture
being drawn to the other side of the world. So
(17:35):
it's it's hard to imagine what life would consist of
in that situation unless you you did have a scenario
where individuals were somehow technologically sustained, or if there was
some sort of trade situation with the with the daylit world.
But but things are gonna be pretty severe there too,
so I guess it would be more like you would
have to have some sort of trade scenario with the
twilight world, like that's the that's the area where civilization
(17:58):
is going to thrive more because you can have the
baked side and the frozen side and only in the
middle of things going to be just right right. And
of course we're talking about you know, if this were
to occur on the Earth, this is not something that
would happen like the next dayking about millions of millions. Yeah, yeah, yeah, right,
but you know, I mean, you'd have life forms that
could not subsist on the on the sunlit side, and
(18:19):
by some versa, well you've seen what happens to say,
like the neighborhoods in Atlanta when when there's a severe
snowstorm like two weeks and it's full on cannibalism and
road warriors in the street. Yeah, Atlanta would not farewell, Yeah,
with this situation at all. But the heat side conscious
sign we could. We could probably roll with that pretty
much what we do in the summer anymore. Yeah, you're right, right,
(18:41):
I mean, actually like eight months of a year. Yeah,
you hear us Florida, you hear us Alabama. All right,
So tell us what you think about all that. Do
you have any thoughts on a tidally locked world? You
have some other great examples from science fiction you would
like to do or fantasy you would like to share
with us. There is I mean, there's a whole wonderful
sub genre of to see zi fi with the dying
(19:02):
art scenario where you have the sun dying, and I
think I did a blog post about that a while back.
It's the fascinating zone of imagination. But I have not
encountered much in the way of tidily locked world. So
send me some examples. I would especially again love to
hear examples that take weather into account. Yeah, especially if
if you've ever come across, uh, some sort of idea
(19:23):
of an extra planet with half of the planet being
a snow globe. Yeah, that's that's That's all I'm interested in, really,
the snow globe part of it. Snow global girl. Yeah
all right. Well, hey, if you want to share it
with us, you can find us on Facebook. You can
find us on Twitter. On Facebook, we are stuff to
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(19:51):
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