Latest / Talking Science / Pluto and the Kuiper Belt

Transcript

Pluto and the Kuiper Belt · Talking Science

0:00
So imagine looking out your window, right, and
0:02
you see this really cute stray cat. Wow. And
0:05
you decide to bring it inside to be your new
0:07
pet. You know, you name it, you feed it, you
0:09
give it this cozy little spot on the rug. As
0:11
one does, yeah. Right. But then the next morning
0:14
you look out your window again and there are
0:16
like a hundred identical cats just sitting in
0:19
your yard. Oh, wow. That is a lot of cats. Yeah.
0:22
So what do you do? Do you bring every single
0:25
one of them inside? Or, I mean, you kind of have
0:29
to rethink what you even consider a house pet.
0:32
Right. And the funny thing is, in the early 2000s,
0:34
astronomers basically looked through their telescopes
0:37
and realized they had this exact same problem,
0:39
but, you know, with planets. That is honestly
0:42
the perfect way to frame one of the most misunderstood
0:45
moments in, like... Modern science. Yeah. Oh,
0:49
absolutely. We are, of course, talking about
0:51
Pluto because, I mean, if you mention in a crowded
0:54
room that Pluto isn't a planet anymore, someone
0:57
is going to bristle. Oh, 100 percent. People
0:59
get genuinely mad about it. They do. It feels
1:02
like this childhood certainty was just snatched
1:05
away. Right. You know, or like astronomers were
1:08
just being. arbitrarily mean to the small distant
1:11
world right like they bullied it out of the solar
1:13
system but today we are diving into some really
1:17
fascinating source material that completely flips
1:20
that whole narrative yeah It really does. So
1:23
the mission for this deep dive is to basically
1:25
unlearn that whole idea of a demotion. We're
1:29
going to explore how Pluto's reclassification
1:30
is actually it's a triumphant story. It really
1:34
is. It's science working exactly how it should.
1:36
Exactly. It's a perfect example of science updating
1:39
itself when the universe, you know, surprises
1:41
us. OK, let's unpack this. We are going to take
1:44
you on a journey to the very edge of our solar
1:47
system today. And we should say we are going
1:49
to do this. Assuming you have zero background
1:51
in astronomy. Zero. None required. Right. We
1:54
aren't going to use heavy jargon without explaining
1:56
it. And we're going to take our time to really
1:58
understand the mechanisms of the cosmos. Because
2:01
we want to explore not just what happened to
2:03
Pluto, but, you know, the mechanics of why it
2:05
happened. The why is the best part. Yeah, because
2:07
the why is where the real magic of the scientific
2:09
method lies. Science is not it's not a static
2:14
list of facts you memorize in the third grade.
2:16
It's an active process of refining our categories
2:19
based on new data, which sometimes requires us
2:22
to, well, abandon our assumptions and look at
2:25
the cosmos with fresh eyes. Which brings us to
2:27
the beginning of the whole mess, because before
2:29
we can really grasp why Pluto lost its planetary
2:32
status, we kind of have to rewind, right? We
2:35
do. We need to understand how it got that status
2:38
in the first place and why it was. Honestly,
2:41
like always a bit of a suspicious fit. Very suspicious.
2:43
So let's go back to 1930, the discovery of Pluto.
2:47
Right. So 1930 was a totally different era for
2:49
astronomy. There were no no automated computer
2:52
guided telescopes mapping the sky in high definition
2:55
like we have now. Yeah. No smartphones to just
2:58
snap a pic of the sky. Exactly. So Pluto was
3:00
discovered by a young American astronomer named
3:02
Clyde Tombaugh. And the way he found it is just
3:05
it's a testament to human endurance. Oh, my gosh.
3:08
Yes. He used a device called a blink comparator.
3:10
I've read about this process and the sheer like.
3:13
The tediousness of it is staggering. It's mind
3:16
-numbing. Right. Because he wasn't just looking
3:18
through an eyepiece, you know, hoping to spot
3:20
a new planet. He was taking these massive glass
3:23
photographic plates of the night sky and capturing
3:26
the exact same patch of space a few days apart.
3:29
Right. And then he would load those two glass
3:32
plates into the blink comparator. And what the
3:35
machine would do is rapidly switch the view back
3:38
and forth between plate A and plate B. Click,
3:41
click, click. Exactly. And the fixed stars, which
3:44
are incredibly far away, they wouldn't move at
3:47
all between the photos. But if there was a planet
3:50
or an asteroid in our solar system, it would
3:52
have moved slightly along its orbit during those
3:54
few days. Right. So by flicking back and forth,
3:56
the human brain's motion detection kicks in.
3:59
Out of like thousands of static white dots, one
4:02
tiny speck would appear to jump or blink back
4:04
and forth. That is the precise mechanism. And
4:07
Tombo spent thousands of hours staring into this
4:09
machine. Thousands of hours. Thousands. Analyzing
4:13
millions of stars, fighting off severe eye strain.
4:17
And eventually he finds a dot that jumps. Wow.
4:20
And it is immediately hailed as the ninth planet.
4:24
The supposed planet X that older astronomers
4:27
had been predicting for years. But wait, if we
4:30
are looking closely at the data from day one,
4:32
Pluto was always an oddball. Like it never really
4:35
fit the profile of a major planet. No, it didn't.
4:38
For starters, the size. We eventually realized
4:40
Pluto is incredibly small, like it's smaller
4:43
than our own moon. Yes. It's wild to think about
4:46
a planet being smaller than the rock orbiting
4:48
our own planet. Yeah, size was definitely the
4:50
first red flag. The early astronomers, they assumed
4:53
they were looking for a massive gas giant, something
4:56
that was actively tugging on the orbits of Uranus
4:58
and Neptune. Right, because they thought some
5:00
gravity was messing with those planets. Exactly.
5:02
So they thought Pluto was huge, but it just appeared
5:04
faint because it was so far away. But as decades
5:08
pass and our measurements got better, Pluto kept
5:11
like shrinking in our estimates. It's getting
5:13
smaller and smaller. Right. Until by the 1970s,
5:16
astronomers realized it was this tiny ice world
5:19
totally lacking the mass to have ever pulled
5:21
on the gas giants in the first place. And it
5:23
wasn't just the mass, right? The orbit was completely
5:25
bizarre. The orbit is a mess. Yeah. So like if
5:28
you picture the solar system, most of the planets
5:31
operate on a tidy, relatively flat plane. Think
5:35
of like an old vinyl record spinning on a turntable.
5:38
Okay, good visual. All the major planets, Earth,
5:41
Mars, Jupiter. They're sitting neatly in the
5:45
grooves of that flat record, but Pluto is completely
5:48
ignoring the record. It is entirely off the plane.
5:50
It's like a moth diving through the record at
5:53
a steep, what, 17 degree angle? Yeah, about 17
5:55
degrees. And not only is it tilted, but its orbit
5:57
is wildly stretched out. It's an oval. It's so
6:00
lopsided that for a 20 year stretch of its 248
6:03
year orbit, Pluto actually dips inside the track
6:07
of Neptune. It does. It sneaks closer to the
6:10
sun than the eighth planet does. It doesn't sound
6:13
like a stable major planet. So I have to ask,
6:17
were astronomers just ignoring these giant red
6:20
flags for decades because they desperately wanted
6:23
a complete set of nine planets? Well, what's
6:26
fascinating here is that science often has to
6:28
work with the best categories and the best technology
6:31
it has at any given time. Okay. Fair. In the
6:34
mid -20th century, we just didn't have the technology
6:36
to see anything else that far out. Yeah. So you
6:39
have this object, right? It orbits the sun. It's
6:41
round. It's far away. Based on the framework
6:44
of the time, the only available box to put it
6:47
in was planet. It was the only label we had.
6:50
Exactly. It wasn't willful ignorance. It was
6:52
simply the limitation of the era's technology.
6:55
We categorized it with the information we had.
6:57
The universe just like hadn't shown us the rest
7:00
of its cards yet. Beautifully put. Yeah. Which
7:02
brings us to the turning point because we stopped
7:05
ignoring the red flags when our telescopes went
7:08
through a massive technological revolution, right?
7:10
We moved away from those glass photographic plates
7:12
and started using CCDs, basically digital sensors,
7:16
like highly advanced versions of the camera in
7:19
your smartphone. Yep. Digital completely changed
7:21
the game. And these digital sensors revealed
7:23
that Pluto was hiding a massive secret about
7:26
the edges of our solar system. Yeah, the technological
7:28
leap in the late 1990s and early 2000s changes
7:32
the entire map of the solar system. Astronomers
7:35
start staring deeply into that same distant freezing
7:38
region where Pluto lives. Right. And they realize
7:41
Pluto is not alone out there, not even close.
7:44
Not by a long shot. No. It turns out Pluto is
7:47
just one piece of a vast donut -shaped ring of
7:51
icy bodies stretching far beyond Neptune. We
7:55
now call this the Kuiper Belt. And for those
7:56
of you listening, if you want a mental picture,
7:58
think of the Kuiper Belt as a second, vastly
8:01
larger asteroid belt. That's a great way to think
8:03
of it. Right, because we have the main asteroid
8:05
belt between Mars and Jupiter, which is mostly
8:08
rock and metal because it's closer to the warmth
8:10
of the sun. But the Kuiper Belt is much further
8:12
out in the deep freeze of space. It is incredibly
8:15
cold out there. Yeah, so the debris out there
8:17
is mostly made of ice and frozen gases, not rock.
8:21
Exactly. And when the solar system formed, Four
8:23
and a half billion years ago from this swirling
8:25
disk of gas and dust, the planet swept up most
8:29
of the material. Right. But at the very fringes,
8:31
the material was too sparse and too cold to clump
8:34
together into a massive planet. It just stayed
8:37
as a vast debris field of primordial ice. It's
8:40
essentially a... cosmic time capsule. Oh, wow,
8:43
a time capsule. Well, and as our digital telescopes
8:46
pierced the darkness of this region, we found
8:49
countless objects, everything from tiny chunks
8:51
of ice to, well, substantial little worlds. And
8:55
the realization slowly dawns on the astronomical
8:57
community. Pluto wasn't the lonely ninth planet
9:00
bringing up the rear of the solar system. Not
9:02
at all. It was just one of the larger members
9:03
of this massive frozen crowd. Yeah. Which brings
9:07
us right back to our stray cat analogy. Yes,
9:09
the cats. You let Pluto in the house, but now
9:11
you have hundreds of icy cats on your lawn. And
9:14
the situation becomes critical in the 2000s because
9:17
astronomers start finding Kuiper Belt objects
9:19
that are roughly Pluto's size, worlds with names
9:22
like Haumea and Makemake. Right. But the absolute
9:25
clincher came in 2005. with the discovery of
9:28
a world named Eris. Okay, I want to pause on
9:31
Eris for a second, because if it was as big as
9:33
Pluto, why did it take until 2005 to find it?
9:36
Like, shouldn't we have seen it earlier? That
9:38
is an excellent question. Eris was incredibly
9:41
hard to find for two main reasons. First, it
9:44
is located in what we call the scattered disk,
9:47
which is much further out than Pluto. Okay, so
9:49
it's darker. Exactly. It reflects way less sunlight,
9:52
and it moves agonizingly slowly across the sky.
9:55
Remember Tom Ball's... link comparator yeah looking
9:57
for the jump right you need an object to move
10:00
noticeably against the background stars but iris
10:03
is moving at a glacial pace and second Its orbit
10:06
is tilted even more crazily than Pluto's. Wait,
10:09
more than 17 degrees? A massive 44 -degree angle
10:12
to the solar system's flat plane. Oh, wow. And
10:14
since astronomers usually scan the flat plane
10:16
where all the other planets are, Eris was just
10:19
hiding way up in the attic of the solar system
10:22
where nobody was looking. Okay, that makes sense.
10:24
But once they finally spot it, they realize Eris
10:27
is a total game -changer. I mean, initial measurements
10:30
actually made it look even bigger and heavier
10:32
than Pluto. Right. And if we connect this to
10:35
the bigger picture, the discovery of Eris created
10:37
a genuine structural dilemma for astronomy. How
10:41
so? Well, if Pluto is a planet, then Eris, being
10:45
practically the same size, absolutely must be
10:47
a planet too. Right. And if those two are planets,
10:50
what about Makemake? What about the next object
10:52
you find? We could be looking at dozens, maybe
10:55
hundreds of Pluto -sized ice balls waiting to
10:57
be discovered in the Kuiper Belt. So we really
11:00
were staring down the barrel of having 50 or
11:02
100 planets. You'd have to update the textbooks
11:04
every six months. Yes. And kids would have to
11:07
memorize a song with 100 planets in it. That
11:09
sounds like a nightmare. It really does. And
11:12
scientifically, if you have 100 planets, including
11:15
countless chunks of ice that are practically
11:17
indistinguishable from one another, the word
11:20
planet... loses all scientific utility. It just
11:24
becomes a meaningless word. Exactly. A category
11:27
that lumps together a massive gas giant like
11:29
Jupiter, which is hundreds of times heavier than
11:32
Earth with a thousand tiny icy rocks, doesn't
11:35
actually help scientists describe the mechanics
11:38
of the universe. The classification system was
11:41
basically buckling under the weight of new data.
11:44
Which forces the scientific community to sit
11:46
down and do something you'd think they would
11:47
have done centuries ago. You would think so,
11:49
yeah. Because the word planet was about to become
11:51
totally meaningless in 2006, the International
11:54
Astronomical Union, the IAU, which is the official
11:57
body that names things in space they gathered
12:00
in Prague, to formally define what a planet actually
12:03
is. And it is genuinely surprising to realize
12:06
that before 2006, science had no strict mathematical
12:09
definition for a planet. That is wild to me.
12:12
Right. It was just a historical assumption. You
12:14
just kind of knew a planet when you saw it. Yeah.
12:16
But Eris forced them to write rules. The IAU
12:20
debated fiercely and ultimately settled on a
12:22
three -part definition. Okay, let's walk through
12:24
this definition because the mechanics of these
12:26
rules are brilliant. The first two rules are
12:28
pretty intuitive. They are. Rule one, it must
12:32
orbit the sun. So that immediately disqualifies
12:35
all the moons orbiting Jupiter and Saturn. Pluto
12:38
orbits the sun, so it passes rule one. Right,
12:41
easy pass. Rule two. It must be big enough that
12:44
its own gravity has pulled it into a round shape.
12:47
And the scientific term for rule two is hydrostatic
12:50
equilibrium. Hydrostatic equilibrium. Yeah, it
12:53
sounds complicated, but it's really just a battle
12:56
between gravity and the structural strength of
12:58
a material. Okay. If an asteroid is small, maybe
13:00
a few miles across, the rock or ice is strong
13:03
enough to hold a weird, lumpy potato shape. Like
13:06
a space potato. Exactly, a space potato. Because
13:10
its gravity is too weak to crush the rock. But
13:13
if an object gathers enough mass, its gravity
13:17
becomes overwhelming. The gravity pulls equally
13:20
from the center in all directions, crushing the
13:22
rock and ice until the whole world smooths out
13:25
into a sphere. Okay, and Pluto is definitely
13:27
massive enough for its gravity to crush it into
13:30
a sphere. So it achieves hydrostatic equilibrium.
13:33
It does. It passes rule two easily. It's two
13:35
for two. So far, we still have our ninth planet,
13:38
but then we hit the trap. Rule three. Yes. The
13:41
third rule is where the line in the sand is drawn.
13:43
To be a true planet, a body must have cleared
13:46
its neighborhood. so what does this all mean
13:48
cleared its neighborhood i've always loved the
13:50
mechanics of this concept let's um let's use
13:52
an everyday analogy okay let's hear it imagine
13:55
a true planet like earth or jupiter as a massive
13:58
heavy -duty snowplow driving down a street the
14:01
street represents the planet's orbit around the
14:03
sun A true planet is so massively heavy and its
14:07
gravitational dominance is so overwhelming that
14:10
over billions of years it sweeps up or violently
14:13
flings away all the other loose debris in its
14:16
path. Right. It pushes everything out of the
14:17
way. Exactly. The street is completely clear
14:20
behind the snowplow. But Pluto, Pluto is just
14:23
a regular car trundling along through a heavy
14:26
snowstorm. It's driving right in the middle of
14:28
a massive swarm of other cars. That analogy gets
14:31
right to the physics of the IAU decision. They
14:34
use something called a planetary discriminant,
14:36
which is essentially a math equation. They compare
14:39
the mass of a planet to the total mass of all
14:41
the other debris sharing its orbit. Okay. Earth
14:45
is over a million times heavier than all the
14:47
stray asteroids in its path combined. A million
14:50
times. Over a million, yeah. It is the undisputed
14:52
gravitational bully of its neighborhood. Pluto,
14:55
on the other hand, is only a fraction of the
14:58
weight of all the other icy bodies swarming around
15:00
in the Kuiper Belt. It isn't the driver, it's
15:02
just the passenger in the swarm. It hasn't cleared
15:04
the street at all. Exactly why Pluto fails the
15:07
third test. It is not gravitationally dominant
15:10
enough to have tidied up its own patch of space.
15:13
Because of this, the IAU had to create a brand
15:16
new category for worlds that pass the first two
15:19
rules but fail the third. And that's how Pluto
15:21
was reclassified as a dwarf planet. Exactly.
15:24
And it's so important to reiterate that this
15:26
wasn't a punishment, like nobody was mad at Pluto.
15:28
No, not at all. It was a necessary reorganization
15:31
of our cosmic filing cabinet. We learned more
15:34
about how the solar system formed, we recognized
15:35
the Kuiper belt, so we just needed better folders
15:38
to organize. organize the information based on
15:40
how gravity actually operates out there. Right.
15:43
But if you think the debate ended neatly in 2006
15:46
with everyone shaking hands and agreeing, you
15:48
would be very wrong. Oh, very wrong. This remains
15:51
a genuinely contentious debate among many serious
15:55
scientists today. Because a lot of critics, especially
15:57
planetary geologists, argue that the cleared
16:01
-its -neighborhood rule is fundamentally flawed.
16:03
Right, because rule three relies on orbital dynamics,
16:06
like where a world is and what's around it. But
16:09
geologists care about what a world is. And here's
16:11
where it gets really interesting. Just as everyone
16:15
is furiously debating this new dwarf planet label
16:18
in the late 2000s, humanity decides to actually
16:22
go there and look at it. Yes, finally. In 2015,
16:25
a NASA spacecraft called New Horizons finally
16:28
reaches Pluto. And the scale of the New Horizons
16:31
mission is just a triumph of engineering. It's
16:34
incredible. It was the fastest spacecraft ever
16:36
launched at the time. It flew for nine and a
16:38
half years, utilizing gravity assist from Jupiter,
16:41
just to pick up enough speed to cross the three
16:43
billion kilometers to the Kuiper Belt. Three
16:45
billion kilometers. Yeah. And it didn't even
16:48
have enough fuel to slow down and orbit Pluto.
16:50
It had to execute a flawless high speed flyby,
16:53
snapping as many pictures as possible in a matter
16:56
of hours. The tension must have been unbearable
16:58
because before 2015, our best pictures of Pluto,
17:01
even using the Hubble Space Telescope, were just
17:04
fuzzy pixelated blobs. Yeah, you could barely
17:06
see anything. Right. So people assumed a tiny
17:08
dwarf planet three billion kilometers away from
17:11
the warmth of the sun would just be a dead, heavily
17:14
cratered lump of ice, just a frozen graveyard.
17:16
That was the expectation, yeah. And then the
17:18
high -definition images start downloading to
17:21
Earth. The imagery astonished everybody. Yeah.
17:23
It completely rewrote our understanding of the
17:25
outer solar system. What did they see? Well,
17:28
New Horizons revealed towering mountains that
17:31
rival the Rockies. Mountains on Pluto. Yes. And
17:34
because the surface temperature is around minus
17:36
380 degrees Fahrenheit, the water ice making
17:40
up those mountains is frozen so solid it acts
17:43
like bedrock. It is as hard as granite. That
17:46
is wild. And surrounded by those mountains of
17:49
water ice, they found this fast, perfectly smooth
17:52
plane, famously shaped like a giant heart. The
17:55
famous Pluto heart, yeah. And this plane is made
17:57
of frozen nitrogen. But here's the crazy part.
18:00
Nitrogen has a lower freezing point than water.
18:02
So even at minus 380 degrees, the nitrogen ice
18:05
remains pliable. Right, it's softer. Yeah, it
18:07
acts like a slow -moving glacier. The images
18:09
showed this nitrogen heart is slowly churning.
18:12
bubbling up from below, erasing all the craters
18:15
on the surface and renewing itself. Pluto even
18:17
has a thin hazy blue atmosphere. And that geological
18:20
activity is what truly shocked the scientific
18:23
community. To see churning nitrogen planes in
18:26
an atmosphere on a world that distant means Pluto
18:30
is geologically alive. But wait, how is that
18:33
mechanically possible? We just established it's
18:35
freezing out there. It's tiny. So shouldn't it
18:38
have lost all its internal heat billions of years
18:40
ago? That is the mystery that makes Pluto so
18:43
spectacular. The prevailing theory is that deep
18:45
inside Pluto, there is a rocky core containing
18:48
trace amounts of radioactive elements. Oh, interesting.
18:51
Yeah, things like uranium or thorium left over
18:54
from the birth of the solar system. As those
18:56
elements decay over billions of years, they release
18:59
a tiny, steady amount of heat. Okay. And because
19:02
Pluto is wrapped in a thick blanket of ice, that
19:04
heat is trapped inside like a cosmic heating
19:06
pad. So that trapped internal heat is slowly
19:09
driving convection currents, pushing the slushy
19:12
nitrogen ice up to the surface to create those
19:14
churning planes. Exactly. I read there are even
19:17
theories that this radioactive heating might
19:19
maintain a liquid water ocean deep beneath the
19:21
ice crust. There are, which brings the debate
19:24
right back to the forefront. The planetary geologists
19:27
look at the New Horizons data. The mountains,
19:31
the glaciers, the complex atmosphere, the potential
19:33
subsurface oceans. And they argue this world
19:36
is incredibly complex. I mean, I have to push
19:39
back on the IAU's strict rules based on this,
19:42
too, because if a world has churning plains,
19:44
geological heat and weather, doesn't it fundamentally
19:47
feel more like a planet than just a piece of
19:49
icy rubble? It certainly feels that way. Right.
19:52
Like, doesn't the sheer complexity of Cluedo
19:54
make that third rule about clearing its neighborhood
19:56
seem a bit arbitrary? Well, this raises an important
19:59
question about how we classify nature. The geologists
20:02
argue that a planet should be defined by its
20:04
intrinsic properties, its geophysics. Does it
20:07
have geology? Does it have a complex surface?
20:09
Right. But the orbital dynamicists, who champion
20:12
the IAU definition, they argue that a planet
20:15
must be defined by its context in the solar system.
20:18
Does it dominate its environment gravitationally?
20:20
It's a clash of perspectives. Exactly. And this
20:23
disagreement is an example of healthy science
20:25
at work. As our sources point out, these scientific
20:29
definitions are often more about usefulness than
20:32
about uncovering some absolute universal truth.
20:36
Usefulness. Let's dig into that. Because the
20:38
label dwarf planet is useful for an astrophysicist
20:41
plotting the architecture of the solar system.
20:44
Yes. It immediately tells them about Pluto's
20:46
location and gravitational context within a belt
20:48
of thousands of other objects. But dwarf planet
20:52
doesn't mean it's a boring rock. No, not at all.
20:54
To understand the architecture of our solar system,
20:57
we need to acknowledge that the inner region
20:59
is dominated by rocky worlds, the middle is dominated
21:02
by gas giants, and the outer fringe is a vast
21:05
swarm of icy bodies. Putting Pluto in the dwarf
21:08
planet category alongside Eris and Makemake helps
21:11
us understand that third zone. We completely
21:13
reframe the narrative when we see this. Pluto
21:16
wasn't demoted because it shrank or because it
21:18
failed. It was reclassified because we realized
21:21
it had a lot of company. It's far better understood
21:23
as the shining king of the Kuiper Belt than as
21:25
the bizarre mismatched runt of the major planets.
21:28
Pluto didn't lose anything in 2006. It gained
21:31
a whole kingdom. It is a profound shift in perspective.
21:34
Science isn't just about preserving the models
21:37
we learned in childhood. It's about remaining
21:38
open to the unknown. Yeah. The story of Pluto's
21:42
reclassification is a reminder. that our mental
21:45
maps of reality must always bow to reality itself,
21:49
no matter how much nostalgia we hold for the
21:52
old maps. So for you listening to this deep dive,
21:54
why should you care about the shifting labels
21:56
of a distant ball of ice? Because this story
21:59
equips you with a much better answer the next
22:01
time you hear someone complain about Pluto's
22:02
demotion. Right. You can explain the mechanics
22:05
of hydrostatic equilibrium or the vastness of
22:07
the Kuiper Belt. You can tell them about the
22:09
mountains of rock -hard water ice, the trapped
22:12
radioactive heat. and the churning nitrogen heart?
22:15
It's just a fascinating world. It really is.
22:18
Pluto is the...