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We thought we knew
our solar system.
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00:00:07,960 --> 00:00:11,522
Turns out we were wrong.
3
00:00:11,523 --> 00:00:13,768
Groundbreaking
observations suggest
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00:00:13,769 --> 00:00:16,282
an unseen ninth planet
5
00:00:16,283 --> 00:00:20,933
may be out there on the
fringes of our solar system.
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And it could be huge,
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5,000 times
more massive than Pluto
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00:00:26,358 --> 00:00:28,990
and 10 times
the mass of the Earth.
9
00:00:29,000 --> 00:00:31,335
We don't get a lot
of revolutions in astronomy.
10
00:00:31,336 --> 00:00:35,234
And here we are on the cusp
of a discovery like this.
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It's crazy to think that,
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as much as we've looked
into the universe,
13
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that there's this ninth planet
out there that we've never seen.
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If planet 9 really is out there,
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what will it be like?
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Is it a rocky super-Earth,
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an icy mega-Pluto,
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or a gassy mini-Neptune?
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00:00:55,810 --> 00:00:58,710
Or is planet 9 an alien world
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stolen from another star?
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00:01:01,491 --> 00:01:05,023
And could it provide
an unlikely home for life
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100 billion miles from the Sun?
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Take a look at the night sky.
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The pattern of stars
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that drifts overhead
appears fixed.
26
00:01:29,725 --> 00:01:32,792
But look for longer,
weeks or months,
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00:01:32,793 --> 00:01:37,285
and you'll see a handful
of the points move.
28
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These slow-moving points
of light are the planets,
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the giant chunks of rock or gas
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that orbit our home star,
the Sun.
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We thought there were eight.
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We were wrong.
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You know, we think
we understand something
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as simple as our solar system.
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We've found all the planets.
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And, right in front of us,
we missed something big.
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A group of astronomers are
studying the Kuiper belt,
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a vast band of icy asteroids
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that sits way, way outside
the orbit of Neptune.
40
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Most of these objects move
in a neat, circular formation
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around the Sun.
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00:02:16,220 --> 00:02:19,386
But the astronomers
are puzzled by a small group
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that appear to break the rules,
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swinging far outside
the main belt
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on wild, extended orbits.
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00:02:28,006 --> 00:02:31,440
Something sitting far outside
the Kuiper belt
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seems to be pulling
these asteroids out of line,
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something the size
of a giant planet.
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Caltech astronomer
Mike Brown hears
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about the wild observations
51
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and is determined to prove
the planet theory wrong.
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When we saw
these alignments of all
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these objects out there,
we thought,
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"ugh, everybody's gonna say
there's a planet.
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We have to very strongly prove
there's not a planet."
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Because, of course, we all know
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there's not another planet
out there. That's ridiculous.
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00:03:03,209 --> 00:03:06,345
Mike asked his
colleague, Konstantin Batygin,
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to run a computer simulation
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00:03:08,196 --> 00:03:11,095
to see what effect
a ninth planet
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should have on the Kuiper belt.
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Stunningly,
the simulation predicts
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elongated orbits identical
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to ones already observed.
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00:03:20,706 --> 00:03:23,872
But the simulation also
spits out a surprise.
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00:03:23,873 --> 00:03:26,949
There should be
a second set of rogue orbits
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that are perpendicular
to the first set.
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00:03:29,593 --> 00:03:31,769
If Mike can locate these weird
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predicted objects
inside the Kuiper belt,
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00:03:35,174 --> 00:03:39,231
planet 9 is almost
certainly real.
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I took these simulation
results to Mike's office
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just a couple doors
down from my office.
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And I said, "look!" You know,
"we've got a huge problem!"
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He said, "no!"
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There's an object
called 2012 dr30
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"which has an orbit just like
the one you're predicting."
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Mike's asteroid fits
the prediction perfectly.
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He searches the records for
more and finds another four
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00:04:03,370 --> 00:04:05,615
that seem to be
in the right area.
80
00:04:05,616 --> 00:04:09,841
But just how closely
will they fit the prediction?
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00:04:09,842 --> 00:04:12,780
I remember sitting back
and thinking,
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"okay, we're going to,
right now, plot the data,
83
00:04:15,750 --> 00:04:19,916
the real observational data
on top of the model."
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00:04:19,917 --> 00:04:21,956
And Mike said,
"if these two match up,
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my jaw is just gonna
drop to the floor."
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The theory says they should be
right here and right here.
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00:04:28,438 --> 00:04:30,248
And I did the
calculations very quickly
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to see where they were
and brought them up.
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And there they are.
One, two, three, four, five,
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right on these lines
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00:04:38,572 --> 00:04:41,609
exactly where we predicted
they should be.
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The moment we saw this,
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we went from cautious
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to "holy cow!
This really is there!"
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We have to make sure
to tell everybody right away
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"because it's actually real!"
97
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Mike and Konstantin had unlocked
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00:04:55,772 --> 00:04:58,315
the solar system's
greatest secret.
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Planet 9 was almost
certainly real.
100
00:05:02,383 --> 00:05:03,995
And it had to be huge,
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00:05:03,996 --> 00:05:07,202
perhaps 10 times
the mass of Earth.
102
00:05:07,203 --> 00:05:09,577
We're not talking about
something like our moon
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or Pluto.
We're talking about something
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that is literally
planet-sized.
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And we're seeing
its gravitational wake
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affecting these other objects.
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The idea that there
could be a giant planet
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that we've never seen
is something I think
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most of people
wouldn't have bet on.
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But the evidence is remarkable!
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00:05:27,639 --> 00:05:29,915
To prove planet 9 exists,
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astronomers need to see it
with their telescopes.
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But there's a problem.
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Computer simulations
only give a broad idea
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of where to find it.
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And planet 9 is incredibly faint
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and almost
inconceivably far away.
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It's much, much farther out
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than we ever expected
to find planets.
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It probably spends
most of its life,
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if it's on an elliptical orbit,
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so far away from the Sun
that we just missed it.
123
00:06:02,218 --> 00:06:05,878
So just how far away
is planet 9?
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00:06:05,879 --> 00:06:09,145
The only way to truly
appreciate its vast orbit
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00:06:09,155 --> 00:06:12,321
is to build a scale model,
126
00:06:12,322 --> 00:06:15,884
perhaps the biggest working
model of the solar system
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ever attempted.
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Planetary scientist Kevin Walsh
is here to call the shots.
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00:06:23,119 --> 00:06:26,712
And he starts
with the size of the Sun.
130
00:06:26,722 --> 00:06:29,255
So what we've got here,
our kickball,
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00:06:29,265 --> 00:06:32,857
is going to set the scale of
our mini-solar system today.
132
00:06:32,858 --> 00:06:36,162
So everything is scaled off
of its relative size
133
00:06:36,163 --> 00:06:39,527
compared to the size of the Sun.
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00:06:39,528 --> 00:06:41,744
Kevin quickly
paces out the position
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00:06:41,745 --> 00:06:43,882
of the inner rocky planets.
136
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All four sit within 60 yards
of the Sun on this scale.
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00:06:48,474 --> 00:06:52,739
And each planet would appear
no bigger than a peppercorn.
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00:06:52,740 --> 00:06:55,442
To make this
a working solar system,
139
00:06:55,451 --> 00:06:57,332
we need to bring on the drones.
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Each drone represents
a different planet.
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00:07:14,631 --> 00:07:16,016
And the orbital speeds
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00:07:16,016 --> 00:07:18,788
have been scaled
so one Earth year
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takes just 30 seconds.
144
00:07:23,251 --> 00:07:24,665
Already, it's clear to see
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how tightly bunched
these inner planets are,
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and how the closest planets
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orbit faster
than those farther out.
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Far beyond the tightly
packed rocky planets
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lies the first
of the gas giant planets,
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00:07:43,984 --> 00:07:47,616
on this scale, just over
a football field from the Sun.
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So, after this 400-foot walk,
we made to to Jupiter,
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the largest planet
in the solar system.
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00:07:54,821 --> 00:07:56,107
But, even by this size scale,
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Jupiter is only about
the size of a lollipop.
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00:08:01,254 --> 00:08:03,935
Another football-field
length lies ahead
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on the walk to Saturn.
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As we look back
across the lake bed,
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I can barely see the drones.
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00:08:10,735 --> 00:08:13,802
We covered a huge distance.
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00:08:13,803 --> 00:08:16,681
The trek out to Uranus
is bigger still,
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three football fields
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or the length
of an aircraft carrier.
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Turns out there's a lot of wind
in the outer solar system!
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So I have to yell.
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Surprising amount of wind
in the outer solar system.
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Tumbleweed, rattlesnakes.
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After Uranus, it's around
200 yards out to Neptune.
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Before the discovery
of planet 9,
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we thought Neptune was the
farthest planet from the Sun,
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around half a mile
on the scale of our model.
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But Neptune's distant orbit
is nothing
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compared to the orbit
of planet 9.
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So here we are.
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We made it to
the orbit of Neptune.
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We're only at the tip
of the iceberg.
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00:08:59,841 --> 00:09:01,583
We need to stop
measuring in feet.
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00:09:01,593 --> 00:09:03,176
And we need to start
thinking in miles.
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We need a car
to get out to planet 9.
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Planet 9 swings out
on a highly elliptical orbit.
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Its closest pass to the Sun
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is a whopping 19 billion miles.
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That's six times wider
than the orbit of Neptune.
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00:09:25,038 --> 00:09:27,313
But, at its farthest point,
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00:09:27,314 --> 00:09:31,896
planet 9
is 112 billion miles away.
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And, on this scale,
that's an incredible 18 miles
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from our kickball-sized Sun.
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So we're here, end of the road.
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We've driven about 18 miles
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00:09:43,099 --> 00:09:45,435
from where we first started
setting up the solar system.
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00:09:45,445 --> 00:09:47,354
But, in the scale
of the solar system,
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it's over 100 billion miles.
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100 billion miles
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00:09:51,779 --> 00:09:55,083
to get out to the furthest
part of planet 9's orbit.
194
00:09:55,084 --> 00:09:56,538
So, to scale,
195
00:09:56,539 --> 00:09:58,776
and we don't know
what planet 9 would look like,
196
00:09:58,785 --> 00:10:02,347
but it's probably about
the size of a B.B.
197
00:10:02,348 --> 00:10:04,555
So this is the challenge
for our astronomers.
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00:10:04,565 --> 00:10:07,830
How do you see a b.B.
From 18 miles away?
199
00:10:07,831 --> 00:10:10,137
This is what we have to do.
200
00:10:10,147 --> 00:10:12,422
It could take years
for our telescopes
201
00:10:12,423 --> 00:10:16,084
to pick out an object
so impossibly faint,
202
00:10:16,085 --> 00:10:18,261
far away as planet 9.
203
00:10:18,262 --> 00:10:21,330
Until then, scientists
can only speculate
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00:10:21,340 --> 00:10:24,931
on what this mysterious world
might be like.
205
00:10:24,932 --> 00:10:27,307
We're in this wonderful moment
right now
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00:10:27,317 --> 00:10:28,999
where we suspect
that planet 9 exists.
207
00:10:29,000 --> 00:10:30,909
But we really have
no idea what it's like.
208
00:10:30,910 --> 00:10:33,879
And that means
our imaginations can run wild.
209
00:10:33,889 --> 00:10:35,402
They're informed by science.
210
00:10:35,403 --> 00:10:37,709
But I love it
when creativity takes hold,
211
00:10:37,719 --> 00:10:38,966
and you just run with it.
212
00:10:41,182 --> 00:10:42,834
So what are the options?
213
00:10:42,835 --> 00:10:45,734
Science suggests
three possibilities.
214
00:10:45,735 --> 00:10:48,515
And the first is astonishing.
215
00:10:48,516 --> 00:10:50,159
Planet 9 could be made
216
00:10:50,168 --> 00:10:52,998
from the same materials
as the Earth,
217
00:10:52,999 --> 00:10:55,145
but 10 times more massive,
218
00:10:55,146 --> 00:10:57,591
a rocky super-Earth.
219
00:10:59,808 --> 00:11:02,647
But what would
this giant, rocky planet
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00:11:02,648 --> 00:11:05,289
look like so far from the Sun?
221
00:11:05,290 --> 00:11:08,882
A bizarre volcanic world
scarred with fire
222
00:11:08,883 --> 00:11:13,574
somehow emerges from the
cold darkness of deep space.
223
00:11:27,973 --> 00:11:31,802
In 2016, astronomers
release astonishing evidence
224
00:11:31,803 --> 00:11:34,049
of a missing ninth planet
225
00:11:34,050 --> 00:11:36,752
on the frozen edges
of our solar system,
226
00:11:36,762 --> 00:11:41,016
100 billion miles from the Sun.
227
00:11:41,017 --> 00:11:42,768
Until our telescopes find it,
228
00:11:42,769 --> 00:11:47,450
we can only guess what this
mysterious planet 9 is like.
229
00:11:47,460 --> 00:11:51,417
But the first option is
perhaps the most surprising.
230
00:11:51,418 --> 00:11:54,584
Planet 9 could be
made from rock,
231
00:11:54,585 --> 00:11:56,039
just like the Earth,
232
00:11:56,040 --> 00:11:58,810
but 10 times more massive,
233
00:11:58,811 --> 00:12:02,086
a so-called rocky super-Earth.
234
00:12:02,087 --> 00:12:04,225
When we looked out
into the universe, we realized
235
00:12:04,234 --> 00:12:06,905
that the most common
type of planet
236
00:12:06,906 --> 00:12:08,093
in the entire galaxy
237
00:12:08,094 --> 00:12:09,806
is something we don't have,
238
00:12:09,816 --> 00:12:12,191
something called a
super-Earth.
239
00:12:15,259 --> 00:12:18,366
The Kepler space
telescope finds alien worlds
240
00:12:18,367 --> 00:12:21,305
by measuring
the tiny dip in light
241
00:12:21,306 --> 00:12:25,462
as a planet passes
in front of its host star.
242
00:12:25,463 --> 00:12:29,856
Most of the alien solar systems
Kepler finds have super-Earths.
243
00:12:29,857 --> 00:12:33,616
So how come our star
doesn't have one?
244
00:12:33,617 --> 00:12:38,179
Could it be possible that planet
9 is our missing super-Earth?
245
00:12:38,180 --> 00:12:41,316
If planet 9 is
a rocky super-Earth,
246
00:12:41,317 --> 00:12:43,553
what will it look like up close?
247
00:12:49,076 --> 00:12:53,163
Planetary geologist Jani
Radebaugh imagines planet 9
248
00:12:53,173 --> 00:12:58,190
as a dramatic world
of fire and ice.
249
00:12:58,191 --> 00:12:59,377
Right now, we're in Iceland.
250
00:12:59,378 --> 00:13:01,386
We're flying over amazing,
251
00:13:01,387 --> 00:13:04,296
beautiful volcanic landscapes
of Iceland.
252
00:13:04,297 --> 00:13:06,641
We think this might be
the perfect landscape
253
00:13:06,642 --> 00:13:09,679
for thinking about what might
be happening on planet 9
254
00:13:09,680 --> 00:13:13,213
if it's a rocky super-Earth.
255
00:13:13,214 --> 00:13:15,321
These black mountains
and lava flows
256
00:13:15,331 --> 00:13:17,438
were created by leftover heat
257
00:13:17,439 --> 00:13:21,100
from the Earth's formation
spilling out onto the surface.
258
00:13:21,101 --> 00:13:25,197
Planet 9, born with so much
more insulating rock,
259
00:13:25,198 --> 00:13:29,522
should have even more of this
leftover heat trapped inside it.
260
00:13:29,523 --> 00:13:30,809
What we're talking
about is a body
261
00:13:30,810 --> 00:13:33,718
that's maybe 10 times
the mass of the Earth.
262
00:13:33,719 --> 00:13:35,827
I'd expect,
because it's so large,
263
00:13:35,837 --> 00:13:37,944
that we should have lots
more internal heat.
264
00:13:37,945 --> 00:13:40,191
And so, even though it's
far away in the solar system,
265
00:13:40,192 --> 00:13:41,408
it's far away from the Sun,
266
00:13:41,409 --> 00:13:43,596
it's still got lots
of its own energy.
267
00:13:50,563 --> 00:13:53,462
Touching down on
the surface of planet 9,
268
00:13:53,463 --> 00:13:55,937
you'd find a world
as inhospitable
269
00:13:55,947 --> 00:13:59,439
as you could imagine.
270
00:13:59,440 --> 00:14:01,290
Billions of miles from the Sun,
271
00:14:01,291 --> 00:14:03,764
the surface is lit
by little more
272
00:14:03,765 --> 00:14:06,239
than the twinkle
of distant stars
273
00:14:06,249 --> 00:14:09,940
and the red glow of intense
geological activity
274
00:14:09,941 --> 00:14:12,483
on the surface.
275
00:14:12,484 --> 00:14:14,007
We can imagine, if we were on
276
00:14:14,008 --> 00:14:16,283
a super rocky Earth planet 9,
277
00:14:16,284 --> 00:14:19,153
we could have a landscape
just like this one.
278
00:14:19,154 --> 00:14:21,370
There should be volcanoes
erupting all the time.
279
00:14:21,371 --> 00:14:23,082
And the other thing
we should see
280
00:14:23,083 --> 00:14:25,992
is lots and lots of ice and
snow blanketing the landscape.
281
00:14:25,993 --> 00:14:28,931
This is because the atmosphere
is so cold
282
00:14:28,932 --> 00:14:30,683
that parts of it have condensed
283
00:14:30,684 --> 00:14:32,593
and settled back down
onto the surface.
284
00:14:32,594 --> 00:14:35,037
You're gonna have volcanoes.
You're gonna have canyons.
285
00:14:35,038 --> 00:14:37,581
You're gonna have plate
tectonics, mountain-building.
286
00:14:37,582 --> 00:14:40,352
All of these processes are still
gonna be going on out there
287
00:14:40,353 --> 00:14:43,093
in what we normally would
think of as the frozen, cold,
288
00:14:43,094 --> 00:14:45,568
and dead world
of the outer solar system.
289
00:14:48,943 --> 00:14:51,119
As hot lava reaches the surface,
290
00:14:51,120 --> 00:14:54,287
it freezes suddenly
in the cold of space,
291
00:14:54,297 --> 00:14:56,275
perhaps forming a weird,
292
00:14:56,276 --> 00:14:59,967
volcanic glass called obsidian,
293
00:14:59,968 --> 00:15:01,224
another feature shared
294
00:15:01,225 --> 00:15:03,668
with the sub-zero
volcanoes of Iceland.
295
00:15:03,669 --> 00:15:06,509
Okay, let's put
this whole thing together.
296
00:15:06,509 --> 00:15:08,686
We have a landscape
297
00:15:08,687 --> 00:15:11,062
that's kind of dimly lit
by starlight,
298
00:15:11,072 --> 00:15:13,347
but maybe also
by the reddish glow
299
00:15:13,348 --> 00:15:17,969
from erupting lavas spreading
across the landscape.
300
00:15:17,970 --> 00:15:20,215
And then, behind you,
you have gases
301
00:15:20,216 --> 00:15:21,760
that are changing
immediately to snow
302
00:15:21,770 --> 00:15:24,243
and falling as snow
down to the surface.
303
00:15:24,244 --> 00:15:27,639
And it would just be a
beautiful, magical landscape.
304
00:15:31,013 --> 00:15:35,002
The case for a giant, rocky
planet 9 is compelling
305
00:15:35,012 --> 00:15:37,248
because it paints
such a vivid picture
306
00:15:37,258 --> 00:15:40,751
of a living volcanic world.
307
00:15:40,752 --> 00:15:42,206
But there's a problem.
308
00:15:45,740 --> 00:15:48,945
If planet 9
is, in fact, a super-Earth,
309
00:15:48,946 --> 00:15:50,985
how did it form?
Where did it form?
310
00:15:50,995 --> 00:15:52,310
We don't have
any other super-Earths
311
00:15:52,311 --> 00:15:53,528
in our solar system.
312
00:15:53,538 --> 00:15:55,112
And the ones we see
around other stars
313
00:15:55,121 --> 00:15:57,457
are typically really
close to their star.
314
00:15:57,467 --> 00:16:00,564
So how did our super-Earth
end up way out there
315
00:16:00,565 --> 00:16:03,701
at the edges
of our solar system?
316
00:16:03,702 --> 00:16:06,670
For planet 9 to be
our rocky super-Earth,
317
00:16:06,671 --> 00:16:09,708
it would've had to have formed
in the inner solar system
318
00:16:09,709 --> 00:16:12,746
and then migrated out
to its current position.
319
00:16:12,747 --> 00:16:14,529
And that's a problem,
320
00:16:14,539 --> 00:16:17,932
because there probably wasn't
enough rocky material left over
321
00:16:17,933 --> 00:16:19,318
in the early solar system
322
00:16:19,319 --> 00:16:22,920
to create both
the massive planet 9
323
00:16:22,921 --> 00:16:27,275
as well as Mercury, Venus,
Earth, and Mars.
324
00:16:27,285 --> 00:16:28,729
It's really hard to imagine
325
00:16:28,730 --> 00:16:31,540
that we could have formed
a 10-Earth-mass planet here
326
00:16:31,541 --> 00:16:33,391
and still formed
the rocky planets
327
00:16:33,392 --> 00:16:36,726
that we see today.
328
00:16:36,727 --> 00:16:38,903
- '- Time for a new theory.
329
00:16:38,904 --> 00:16:42,010
What if planet 9 formed from ice
330
00:16:42,011 --> 00:16:44,941
in the outer solar system?
331
00:16:44,951 --> 00:16:47,919
Calculations tell us
it would have to be 10 times
332
00:16:47,920 --> 00:16:49,235
the mass of the Earth.
333
00:16:49,236 --> 00:16:51,185
And here's the kicker.
334
00:16:51,186 --> 00:16:53,363
An ice world that big
335
00:16:53,373 --> 00:16:57,391
would have an internal ocean
of liquid water.
336
00:16:57,401 --> 00:16:59,537
A new world is revealed
337
00:16:59,538 --> 00:17:02,081
where icy geysers
shoot through cracks
338
00:17:02,082 --> 00:17:03,665
in the frozen crust.
339
00:17:03,675 --> 00:17:05,060
And deep below it
340
00:17:05,061 --> 00:17:07,464
lies the largest body
of liquid water
341
00:17:07,465 --> 00:17:09,118
in the solar system.
342
00:17:32,464 --> 00:17:34,245
The planets that make up
our solar system
343
00:17:34,246 --> 00:17:37,748
seem to follow a pattern.
344
00:17:37,749 --> 00:17:42,043
The four closest to the Sun
are all made from rock.
345
00:17:42,044 --> 00:17:46,764
The next four are giants
made mostly from gas.
346
00:17:46,765 --> 00:17:49,565
Beyond Neptune, gas is replaced
347
00:17:49,575 --> 00:17:52,939
by multiple worlds
made from ice.
348
00:17:52,940 --> 00:17:54,750
This is the Kuiper belt,
349
00:17:54,751 --> 00:17:57,986
a frozen realm
of water-ice asteroids,
350
00:17:57,987 --> 00:18:00,332
millions of them.
351
00:18:00,333 --> 00:18:02,776
The Kuiper belt
is a region of space
352
00:18:02,777 --> 00:18:04,627
outside of Neptune's orbit
353
00:18:04,628 --> 00:18:06,309
that extends out,
354
00:18:06,310 --> 00:18:09,120
eh, about 50 times the distance
from the Earth to the Sun.
355
00:18:09,121 --> 00:18:10,971
So it's really far out there.
356
00:18:10,972 --> 00:18:13,109
And this is populated
by icy bodies.
357
00:18:13,119 --> 00:18:15,424
These are giant chunks of ice
358
00:18:15,425 --> 00:18:17,404
that have some rock
and other things in them.
359
00:18:17,405 --> 00:18:19,879
But they're mostly ice.
360
00:18:19,889 --> 00:18:23,252
Perhaps planet 9 is
made from the same materials,
361
00:18:23,253 --> 00:18:25,955
an overgrown version
of the Kuiper belt's
362
00:18:25,965 --> 00:18:29,162
most infamous citizen, Pluto.
363
00:18:31,576 --> 00:18:33,090
Poor Pluto.
364
00:18:33,091 --> 00:18:36,128
Discovered in 1930
by Clyde Tombaugh,
365
00:18:36,129 --> 00:18:38,077
this tiny ice world,
366
00:18:38,078 --> 00:18:39,562
smaller than our moon,
367
00:18:39,563 --> 00:18:43,293
was quickly proclaimed
the ninth planet.
368
00:18:43,294 --> 00:18:47,618
But, in the 1990s, Mike brown
and others discovered
369
00:18:47,619 --> 00:18:51,913
a host of icy worlds
orbiting out with Pluto.
370
00:18:51,914 --> 00:18:55,248
Pluto was just another
Kuiper belt object
371
00:18:55,249 --> 00:18:57,692
and got demoted to dwarf planet,
372
00:18:57,693 --> 00:19:00,335
to the dismay
of much of the world.
373
00:19:00,336 --> 00:19:04,689
Everybody loves the idea
that I killed Pluto,
374
00:19:04,690 --> 00:19:07,866
and now I'm trying
to atone for my sins
375
00:19:07,867 --> 00:19:11,330
by replacing it
with a new ninth planet.
376
00:19:11,331 --> 00:19:13,576
In fact, even my daughter
suggested this
377
00:19:13,577 --> 00:19:16,249
long before we started
looking for planet 9.
378
00:19:16,250 --> 00:19:19,386
She said, you know,
"you should find a new planet."
379
00:19:19,387 --> 00:19:21,167
And then you can have
found a planet.
380
00:19:21,168 --> 00:19:22,988
And there'll be
nine planets again.
381
00:19:22,989 --> 00:19:25,136
"And everybody
will like you again."
382
00:19:25,137 --> 00:19:29,292
If planet 9
is an icy Kuiper belt world,
383
00:19:29,293 --> 00:19:33,221
it'll be the biggest
we've ever found.
384
00:19:33,222 --> 00:19:35,438
Pluto, the biggest object
385
00:19:35,439 --> 00:19:37,388
we know out there
in the Kuiper belt now,
386
00:19:37,389 --> 00:19:39,922
is less than 1%
the mass of the Earth,
387
00:19:39,932 --> 00:19:41,445
less than that.
388
00:19:41,446 --> 00:19:44,256
Planet 9, we think, is 10
times the mass of the Earth.
389
00:19:44,257 --> 00:19:47,591
So we're dealing with a factor
of thousands of times in mass
390
00:19:47,592 --> 00:19:50,035
between the largest
Kuiper belt object
391
00:19:50,036 --> 00:19:51,847
that we know now
392
00:19:51,848 --> 00:19:54,321
and the size of planet 9.
393
00:19:54,322 --> 00:19:58,350
So you're talking about
super-mega-ultra-Pluto.
394
00:19:58,359 --> 00:20:00,239
It's really, really big.
395
00:20:00,240 --> 00:20:03,376
And it's hard to know
what an ice ball
396
00:20:03,377 --> 00:20:05,652
like that would look like.
397
00:20:05,653 --> 00:20:09,611
It's not crazy to speculate that
there could still be activity,
398
00:20:09,612 --> 00:20:11,234
internal geologic activity,
399
00:20:11,235 --> 00:20:13,807
keeping this world
from being cold
400
00:20:13,808 --> 00:20:16,380
and totally dead.
401
00:20:16,381 --> 00:20:18,102
Peering through the darkness
402
00:20:18,103 --> 00:20:21,863
to a hypothetical
mega-Pluto planet 9,
403
00:20:21,864 --> 00:20:25,099
we discover
a giant world of ice.
404
00:20:25,100 --> 00:20:28,503
There's much less rock
than a super-Earth planet 9.
405
00:20:28,504 --> 00:20:31,542
But the mass of ice alone
creates enough gravity
406
00:20:31,543 --> 00:20:36,431
to generate warmth deep in
the core, even out here.
407
00:20:36,432 --> 00:20:40,221
The real currency of keeping
a planet alive is mass.
408
00:20:40,222 --> 00:20:43,131
Does it have enough mass
to keep the interior warm?
409
00:20:43,132 --> 00:20:44,981
Well, something
that's 5 to 10 times
410
00:20:44,982 --> 00:20:49,474
the mass of the Earth
probably would be warm inside.
411
00:20:49,475 --> 00:20:53,661
Up close, the surface
explodes with activity.
412
00:20:53,662 --> 00:20:58,481
But these volcanoes
spew water ice, not lava.
413
00:20:58,491 --> 00:21:00,697
If something like
a giant Pluto exists,
414
00:21:00,698 --> 00:21:02,647
it must be the most
amazing landscape
415
00:21:02,648 --> 00:21:04,032
to take a walk over.
416
00:21:04,033 --> 00:21:07,466
You'd have these ice volcanoes
spewing out jets
417
00:21:07,467 --> 00:21:10,435
of frozen water,
of ice raining down on you.
418
00:21:10,436 --> 00:21:12,218
Maybe you'd look out
over the landscape
419
00:21:12,227 --> 00:21:14,662
and see hundreds
of these erupting.
420
00:21:14,672 --> 00:21:17,997
This dramatic,
icy vista is a gateway
421
00:21:18,007 --> 00:21:19,787
to a secret world,
422
00:21:19,788 --> 00:21:22,786
a vast, slushy ocean
of liquid water
423
00:21:22,787 --> 00:21:24,766
mixed with ice crystals,
424
00:21:24,776 --> 00:21:26,220
perhaps the largest
425
00:21:26,221 --> 00:21:28,833
single body of water
in the solar system.
426
00:21:28,834 --> 00:21:31,041
There's gonna be enough
internal heat, maybe,
427
00:21:31,051 --> 00:21:34,147
to turn this
into a slushy water world.
428
00:21:34,148 --> 00:21:37,018
So it's not quite
a terrestrial, rocky planet.
429
00:21:37,028 --> 00:21:39,501
And it's not
a Uranus or Neptune.
430
00:21:39,502 --> 00:21:42,500
It's a true mega-ocean world,
431
00:21:42,501 --> 00:21:46,399
but perhaps a very cold one.
432
00:21:46,400 --> 00:21:49,932
Is planet 9 an icy mega-Pluto?
433
00:21:49,933 --> 00:21:51,843
The problem is scale.
434
00:21:51,853 --> 00:21:55,910
Pluto and the other objects
in the Kuiper belt are tiny.
435
00:21:55,911 --> 00:21:58,415
So how could the same
building materials
436
00:21:58,425 --> 00:22:02,481
have come together
to form a giant?
437
00:22:02,482 --> 00:22:04,392
So, the idea that planet 9
438
00:22:04,402 --> 00:22:08,756
is simply a really scaled-up
Pluto, a mega-Pluto,
439
00:22:08,757 --> 00:22:10,408
has some difficulties.
440
00:22:10,409 --> 00:22:14,070
We just don't think that there
was enough mass out there
441
00:22:14,071 --> 00:22:15,921
in the far reaches
of the solar system
442
00:22:15,922 --> 00:22:18,327
to all come together
to build a planet that large.
443
00:22:18,337 --> 00:22:20,315
When you look
at the Kuiper belt,
444
00:22:20,316 --> 00:22:22,195
there are all of these
small, icy bodies.
445
00:22:22,196 --> 00:22:24,205
There's nothing
very big out there.
446
00:22:24,215 --> 00:22:26,253
And we think that's not
a coincidence,
447
00:22:26,254 --> 00:22:28,470
that the disk of dust and gas
that formed the planets
448
00:22:28,471 --> 00:22:30,647
had more stuff
closer to the Sun.
449
00:22:30,648 --> 00:22:32,567
And by the time you got out
to where Pluto is,
450
00:22:32,568 --> 00:22:35,269
there wasn't much material
to build planets out of,
451
00:22:35,270 --> 00:22:36,595
certainly not a planet
452
00:22:36,596 --> 00:22:40,949
5 to 10 times
the mass of the Earth.
453
00:22:40,950 --> 00:22:45,571
So, if planet 9 didn't form
in the icy outer system
454
00:22:45,572 --> 00:22:49,203
and didn't form in the rocky,
inner solar system,
455
00:22:49,204 --> 00:22:51,123
where did it come from?
456
00:22:51,124 --> 00:22:53,133
The more likely option,
457
00:22:53,143 --> 00:22:56,111
planet 9 formed
in the gas-rich zone
458
00:22:56,112 --> 00:22:58,219
in the middle
of our solar system
459
00:22:58,220 --> 00:23:02,484
that also created Jupiter,
Saturn, and Neptune.
460
00:23:02,485 --> 00:23:05,522
A gassy planet 9
could be similar to Neptune,
461
00:23:05,523 --> 00:23:08,957
but perhaps a little smaller,
462
00:23:08,958 --> 00:23:10,867
a mini-Neptune.
463
00:23:10,868 --> 00:23:13,479
But how would it get
so much farther out
464
00:23:13,480 --> 00:23:15,360
than the other gas giants?
465
00:23:15,361 --> 00:23:18,299
And what would it look like?
466
00:23:18,300 --> 00:23:21,535
Imagine a weird,
translucent world
467
00:23:21,536 --> 00:23:25,693
glowing in the dark like a
giant deep-sea creature.
468
00:23:43,170 --> 00:23:45,604
Something on the fringes
of our solar system
469
00:23:45,605 --> 00:23:49,039
is upsetting orbits
and causing a ruckus.
470
00:23:49,049 --> 00:23:51,848
Could it be a planet?
471
00:23:51,849 --> 00:23:53,957
It's incredible to me
that we now know
472
00:23:53,967 --> 00:23:55,579
of thousands of other planets
473
00:23:55,580 --> 00:23:57,628
going around other stars
in the sky,
474
00:23:57,629 --> 00:24:00,399
but we may have
missed a big planet
475
00:24:00,400 --> 00:24:02,517
in our own solar system.
476
00:24:02,518 --> 00:24:06,209
Planet 9, a world
we know almost nothing about,
477
00:24:06,219 --> 00:24:10,177
beyond the possibility
that it exists.
478
00:24:10,178 --> 00:24:14,868
Science suggests
intriguing options...
479
00:24:14,869 --> 00:24:18,262
a giant, rocky world
with a heart of fire,
480
00:24:18,263 --> 00:24:20,905
or an ice world filled
481
00:24:20,906 --> 00:24:23,913
with a giant, slushy ocean.
482
00:24:23,914 --> 00:24:28,268
But problems with each theory
have led to new hunches.
483
00:24:28,269 --> 00:24:31,247
So, if it's not a rocky,
metallic super-Earth
484
00:24:31,248 --> 00:24:35,403
and it's not a gigantic,
ice-ball, mega-Pluto,
485
00:24:35,404 --> 00:24:36,888
what's left?
486
00:24:36,889 --> 00:24:39,530
And the answer is a gas giant.
487
00:24:39,531 --> 00:24:43,726
And that strikes me as being
the most likely prospect.
488
00:24:43,727 --> 00:24:46,893
When you think about
the mass of planet 9
489
00:24:46,894 --> 00:24:49,733
and where it is now,
my best guess,
490
00:24:49,734 --> 00:24:54,494
it's something like a
miniature version of Neptune.
491
00:24:54,495 --> 00:24:56,404
The gas giant planets
492
00:24:56,405 --> 00:24:59,374
are the monsters
of our solar system.
493
00:24:59,384 --> 00:25:01,818
Instead of a solid surface,
like the Earth,
494
00:25:01,828 --> 00:25:05,320
the gas giants have thick,
stormy atmospheres
495
00:25:05,321 --> 00:25:08,428
that descend for tens
of thousands of miles,
496
00:25:08,429 --> 00:25:11,269
shrouding their small,
rocky cores.
497
00:25:13,447 --> 00:25:15,950
Jupiter is
the largest gas giant,
498
00:25:15,960 --> 00:25:19,582
over 300 times
the mass of Earth.
499
00:25:19,592 --> 00:25:20,878
Moving out from Jupiter,
500
00:25:20,879 --> 00:25:24,371
the gas giants
get progressively smaller,
501
00:25:24,372 --> 00:25:28,301
Saturn, then Uranus,
and finally Neptune,
502
00:25:28,311 --> 00:25:32,131
around 17 times
the mass of the Earth.
503
00:25:32,141 --> 00:25:34,972
If planet 9 is a gas giant,
504
00:25:34,981 --> 00:25:37,019
it'll be even smaller,
505
00:25:37,020 --> 00:25:39,167
a mini-Neptune.
506
00:25:39,168 --> 00:25:41,345
If planet 9 is a mini-Neptune,
507
00:25:41,355 --> 00:25:43,165
if it's a lot like Neptune,
508
00:25:43,166 --> 00:25:44,977
then it's not really like
509
00:25:44,987 --> 00:25:46,500
a terrestrial planet,
like Earth.
510
00:25:46,501 --> 00:25:49,044
But it's not really like
a gas giant, like Jupiter.
511
00:25:49,045 --> 00:25:51,350
Neptune is this weird,
in-between thing
512
00:25:51,360 --> 00:25:53,735
where it's probably got
a rocky core.
513
00:25:53,736 --> 00:25:56,605
But it's actually, mostly,
what astronomers call ices.
514
00:25:56,606 --> 00:26:00,207
It's got methane in it and water
and various other substances
515
00:26:00,208 --> 00:26:03,305
and a very, very, very thick
atmosphere on top of that.
516
00:26:07,769 --> 00:26:10,470
Neptune's thick clouds
are stained blue
517
00:26:10,471 --> 00:26:12,587
with molecules of methane.
518
00:26:12,588 --> 00:26:17,209
But planet 9's atmosphere
could be transparent.
519
00:26:17,210 --> 00:26:20,218
It's so cold out there,
you're getting almost
520
00:26:20,219 --> 00:26:22,296
no extra energy from the Sun.
521
00:26:22,297 --> 00:26:24,176
And so then anything
heavy in the atmosphere,
522
00:26:24,177 --> 00:26:26,225
any heavier molecule, over time,
523
00:26:26,226 --> 00:26:28,274
would have probably
fallen to the surface.
524
00:26:28,275 --> 00:26:30,184
And only the lightest elements,
525
00:26:30,185 --> 00:26:33,123
the lightest molecules,
would stay in your atmosphere,
526
00:26:33,124 --> 00:26:36,260
so maybe just almost
pure hydrogen or helium.
527
00:26:36,261 --> 00:26:39,595
And you'd have, maybe,
a really clear atmosphere.
528
00:26:39,596 --> 00:26:41,644
What would
a mini-Neptune look like
529
00:26:41,645 --> 00:26:43,326
that far out from the Sun?
530
00:26:43,327 --> 00:26:45,900
The thing I think of are
things like jellyfish, right?
531
00:26:45,910 --> 00:26:47,621
That sort of beautiful,
translucent look,
532
00:26:47,622 --> 00:26:50,957
where you're looking through to
the innards of the organism.
533
00:26:50,957 --> 00:26:52,411
In this case,
you might look through
534
00:26:52,412 --> 00:26:55,807
to the innards
of the planet in some way.
535
00:26:55,817 --> 00:26:58,350
The atmosphere
may be transparent.
536
00:26:58,360 --> 00:27:01,031
But this planet
is far from calm.
537
00:27:01,032 --> 00:27:04,526
The interior is lit by
the flash of thunderstorms.
538
00:27:04,536 --> 00:27:07,168
And faint lights
dance around the poles
539
00:27:07,178 --> 00:27:09,750
as solar winds
from distant stars
540
00:27:09,751 --> 00:27:12,689
stream down the planet's
magnetic fields.
541
00:27:12,690 --> 00:27:14,698
Looking into the
innards of the planet,
542
00:27:14,699 --> 00:27:17,272
it would look, in some ways,
like these gorgeous,
543
00:27:17,282 --> 00:27:21,240
beautiful deep-sea organisms
that are bioluminescent.
544
00:27:21,241 --> 00:27:23,190
And we may have
the planetary equivalent
545
00:27:23,191 --> 00:27:25,961
of something like out there in
the inky blackness of space,
546
00:27:25,962 --> 00:27:30,285
rather than the inky blackness
of the deep ocean.
547
00:27:30,286 --> 00:27:33,353
Could planet 9
be a mini-Neptune?
548
00:27:33,354 --> 00:27:36,926
Surprisingly, the possibility
of an extra gas giant
549
00:27:36,927 --> 00:27:39,994
in our solar system isn't new.
550
00:27:39,995 --> 00:27:42,567
In 2011, scientists attempted
551
00:27:42,568 --> 00:27:43,824
to replicate the formation
552
00:27:43,825 --> 00:27:47,159
of our solar system
using supercomputers.
553
00:27:47,160 --> 00:27:49,208
But their models didn't work
554
00:27:49,209 --> 00:27:54,621
unless they added an extra
gas giant planet to the mix.
555
00:27:54,622 --> 00:27:56,799
It was really
difficult to reproduce
556
00:27:56,809 --> 00:27:58,887
our current solar system.
557
00:27:58,888 --> 00:28:00,668
But one scientist found that,
558
00:28:00,669 --> 00:28:03,508
if you add a fifth large planet
559
00:28:03,509 --> 00:28:04,894
to our solar system,
560
00:28:04,895 --> 00:28:07,536
then that planet will end up
561
00:28:07,537 --> 00:28:09,743
getting ejected
from our solar system.
562
00:28:09,744 --> 00:28:12,654
And you'd have the planets
that we have today.
563
00:28:14,574 --> 00:28:16,978
Is planet 9
the missing gas giant
564
00:28:16,979 --> 00:28:19,689
predicted by the supercomputers?
565
00:28:19,690 --> 00:28:21,965
The computer model
shows it being ejected
566
00:28:21,966 --> 00:28:24,371
by the immense gravity
of Jupiter.
567
00:28:24,381 --> 00:28:28,665
But did planet 9 instead
cling to our solar system
568
00:28:28,666 --> 00:28:32,337
by the tips of its
gravitational fingers?
569
00:28:32,338 --> 00:28:34,019
Sometimes,
our mathematical models
570
00:28:34,020 --> 00:28:35,900
predict things
that we think are impossible.
571
00:28:35,901 --> 00:28:37,454
And then we find them.
572
00:28:37,455 --> 00:28:39,106
And, for a while,
we've known that,
573
00:28:39,107 --> 00:28:40,591
if you throw a mini-Neptune
574
00:28:40,592 --> 00:28:42,699
into the mix of planets forming,
575
00:28:42,700 --> 00:28:44,223
the models work better.
576
00:28:44,224 --> 00:28:48,053
Maybe we found that key,
finally... planet 9.
577
00:28:48,054 --> 00:28:51,190
We know giant planets
can get thrown around.
578
00:28:51,191 --> 00:28:53,794
Observers have even seen
ejected planets
579
00:28:53,804 --> 00:28:57,426
floating free in the space
between stars.
580
00:28:57,436 --> 00:29:01,492
Did planet 9 almost
suffer the same fate?
581
00:29:01,493 --> 00:29:04,135
It's entirely possible
that there could've been
582
00:29:04,136 --> 00:29:05,550
a planet forming
bigger than Earth,
583
00:29:05,551 --> 00:29:07,569
something like a super-Earth,
well on its way
584
00:29:07,570 --> 00:29:09,083
to becoming a gas giant
585
00:29:09,084 --> 00:29:12,092
in this wonderful area
of the disk,
586
00:29:12,093 --> 00:29:13,843
where it could've drawn in
a lot of material
587
00:29:13,844 --> 00:29:15,892
and become a gas giant
like Jupiter,
588
00:29:15,893 --> 00:29:18,237
except it got
too close to Jupiter.
589
00:29:18,238 --> 00:29:19,751
And, before it could do that,
590
00:29:19,752 --> 00:29:22,028
it was gravitationally
thrown away
591
00:29:22,029 --> 00:29:24,343
from this wonderful
feeding ground
592
00:29:24,344 --> 00:29:26,194
out into the much sparser,
593
00:29:26,195 --> 00:29:29,065
more barren desert
of the outer solar system.
594
00:29:32,004 --> 00:29:35,368
Is planet 9 really
a frozen mini-Neptune
595
00:29:35,369 --> 00:29:38,802
banished to the badlands
of the outer solar system?
596
00:29:38,803 --> 00:29:41,484
Right now, it's our best bet.
597
00:29:41,485 --> 00:29:44,186
But there is one more option.
598
00:29:44,187 --> 00:29:46,007
Some scientists believe
599
00:29:46,008 --> 00:29:49,798
planet 9 may not have formed
around our Sun at all.
600
00:29:53,144 --> 00:29:55,349
Is our most distant planet
601
00:29:55,350 --> 00:29:58,884
an alien world snatched
from another star?
602
00:30:18,667 --> 00:30:21,437
If the mysterious
planet 9 exists,
603
00:30:21,438 --> 00:30:23,942
it is by far
the most distant planet
604
00:30:23,952 --> 00:30:25,336
in the solar system,
605
00:30:25,337 --> 00:30:28,176
20 times farther out
than Neptune.
606
00:30:28,177 --> 00:30:30,720
So how did it get there?
607
00:30:30,721 --> 00:30:34,451
Was it made in the place
it currently occupies?
608
00:30:34,452 --> 00:30:37,054
Or was it flung out
from the inner solar system
609
00:30:37,055 --> 00:30:38,578
as a rocky super-Earth
610
00:30:38,579 --> 00:30:42,012
or, more likely, a
mini-Neptune?
611
00:30:42,013 --> 00:30:43,694
The jury's out.
612
00:30:43,695 --> 00:30:46,595
But there is another option.
613
00:30:46,605 --> 00:30:48,385
And it's out of this world.
614
00:30:48,386 --> 00:30:51,087
So the question is, then,
where did it come from
615
00:30:51,088 --> 00:30:52,542
if neither of these things
is right?
616
00:30:52,543 --> 00:30:56,075
And it's possible that
there is another explanation.
617
00:30:56,076 --> 00:30:59,905
And that is that planet 9
is an alien visitor
618
00:30:59,906 --> 00:31:01,727
from outer space.
619
00:31:04,666 --> 00:31:08,099
The Sun is just 1
of 200 billion stars
620
00:31:08,100 --> 00:31:10,742
orbiting the supermassive
black hole
621
00:31:10,743 --> 00:31:13,809
at the center
of the milky way galaxy.
622
00:31:13,810 --> 00:31:17,244
Most of these stars probably
have multiple planets.
623
00:31:17,245 --> 00:31:20,777
And scientists now believe
that, from time to time,
624
00:31:20,778 --> 00:31:24,736
two stars might pass a little
too close for comfort.
625
00:31:24,746 --> 00:31:29,160
The result... planetary theft.
626
00:31:29,170 --> 00:31:31,376
We know that the Sun moves
around in the galaxy.
627
00:31:31,377 --> 00:31:32,959
We know that there
are other stars
628
00:31:32,960 --> 00:31:34,147
and other solar systems.
629
00:31:34,148 --> 00:31:36,859
Is it possible that
the Sun passed so close
630
00:31:36,860 --> 00:31:38,145
to another solar system
631
00:31:38,146 --> 00:31:41,678
that it stole a planet?
632
00:31:41,679 --> 00:31:44,549
Today, our Sun
drifts through space alone,
633
00:31:44,559 --> 00:31:47,488
like a yacht in the open ocean.
634
00:31:47,489 --> 00:31:49,803
But that wasn't always the case.
635
00:31:49,804 --> 00:31:53,040
Rewind the clock
4.6 billion years,
636
00:31:53,041 --> 00:31:57,265
and our local star cluster
was a much more crowded place,
637
00:31:57,266 --> 00:32:01,126
ideal conditions
for planet 9 to jump ship.
638
00:32:03,145 --> 00:32:04,995
The Sun was born in a nursery
639
00:32:04,996 --> 00:32:07,073
with thousands of other stars.
640
00:32:07,074 --> 00:32:08,924
Just like the boats
in this harbor,
641
00:32:08,925 --> 00:32:12,061
there are so many boats
around, so many neighbors.
642
00:32:12,062 --> 00:32:13,972
It was like that
for the young Sun.
643
00:32:15,921 --> 00:32:19,355
Stars like the Sun
are born in stellar nurseries,
644
00:32:19,355 --> 00:32:21,731
vast clouds of gas that collapse
645
00:32:21,741 --> 00:32:24,639
to form tens of thousands
of stars,
646
00:32:24,640 --> 00:32:26,986
all tightly packed together.
647
00:32:28,965 --> 00:32:31,043
Astronomers think it's possible
648
00:32:31,053 --> 00:32:35,209
that, inside this cramped,
confused playground of stars,
649
00:32:35,210 --> 00:32:38,445
our Sun's gravity
could've stolen planet 9
650
00:32:38,446 --> 00:32:40,395
from a passing neighbor.
651
00:32:40,396 --> 00:32:42,107
Imagine this cool scenario.
652
00:32:42,108 --> 00:32:44,087
You've got an alien star.
653
00:32:44,097 --> 00:32:46,234
And around that star
forms a planet.
654
00:32:46,235 --> 00:32:47,620
This is planet 9.
655
00:32:47,630 --> 00:32:49,668
And here comes the Sun
whizzing by.
656
00:32:49,669 --> 00:32:52,409
The Sun gets so close
that it steals planet 9
657
00:32:52,410 --> 00:32:56,081
on its way out into the galaxy.
658
00:32:56,082 --> 00:32:58,357
It sounds like science fiction.
659
00:32:58,358 --> 00:33:02,445
But our Sun may already
have a criminal record.
660
00:33:02,455 --> 00:33:05,750
There's some evidence that
the comets in our solar system
661
00:33:05,751 --> 00:33:07,829
may not have started
in our solar system.
662
00:33:07,839 --> 00:33:10,966
We may have stolen comets
from other stars.
663
00:33:10,976 --> 00:33:12,489
If that's the case,
664
00:33:12,490 --> 00:33:14,103
it's not totally outrageous
665
00:33:14,113 --> 00:33:17,903
to think that a planet that
formed around another star
666
00:33:17,904 --> 00:33:20,675
somehow made its way
into our solar system
667
00:33:20,685 --> 00:33:24,147
and became part of our family.
668
00:33:24,148 --> 00:33:26,918
But if planet 9 really did
come from another star,
669
00:33:26,919 --> 00:33:30,353
how will we know for sure
that it's an alien visitor?
670
00:33:30,354 --> 00:33:32,302
What we'd like to do
is essentially
671
00:33:32,303 --> 00:33:34,677
a DNA test on planet 9,
672
00:33:34,678 --> 00:33:36,627
scoop up some of its surface
673
00:33:36,628 --> 00:33:40,587
and look for material
that we absolutely know
674
00:33:40,596 --> 00:33:42,278
couldn't have formed
around our Sun,
675
00:33:42,279 --> 00:33:44,653
because we don't see it anywhere
else in our solar system.
676
00:33:44,654 --> 00:33:46,563
We may even have
to send a probe there
677
00:33:46,564 --> 00:33:48,285
to really get a good look at it
678
00:33:48,286 --> 00:33:50,561
and find out what
its chemical composition is,
679
00:33:50,562 --> 00:33:53,570
exactly everything we can
find out about its orbit.
680
00:33:53,571 --> 00:33:54,985
And, that way,
we might be able to see
681
00:33:54,986 --> 00:33:57,856
if there are any
sort of fingerprints,
682
00:33:57,866 --> 00:34:00,004
smoking-gun pieces of evidence
683
00:34:00,014 --> 00:34:02,942
that'll say clearly
this formed here
684
00:34:02,943 --> 00:34:05,259
or it formed out there.
685
00:34:08,891 --> 00:34:13,017
Unfortunately, before we can
686
00:34:13,018 --> 00:34:16,778
we first have to find it.
687
00:34:16,788 --> 00:34:18,232
Astronomers like Mike brown
688
00:34:18,233 --> 00:34:20,410
have made the challenge
a little easier,
689
00:34:20,420 --> 00:34:23,913
using math
to narrow down the zone.
690
00:34:23,914 --> 00:34:26,328
What we know right now
is that planet 9
691
00:34:26,329 --> 00:34:29,425
is in a swath of the sky
that goes about like this.
692
00:34:29,426 --> 00:34:31,741
It's about this big.
It goes across like this.
693
00:34:31,742 --> 00:34:33,987
But we think we even know
a little bit better.
694
00:34:33,988 --> 00:34:36,363
We've pinpointed, or at least
slightly constrained
695
00:34:36,364 --> 00:34:39,926
where it is, to a patch of sky
that's about this big.
696
00:34:39,936 --> 00:34:41,647
It's still a lot of sky
to look at.
697
00:34:41,648 --> 00:34:45,705
But it's a lot less than having
to look at the whole sky.
698
00:34:45,706 --> 00:34:50,328
Mike's patch of sky is close
699
00:34:50,338 --> 00:34:51,752
he's going to wait until fall,
700
00:34:51,753 --> 00:34:53,663
when Orion is highest
in the sky,
701
00:34:53,673 --> 00:34:55,483
to search for planet 9
702
00:34:55,484 --> 00:35:00,234
using the Subaru infrared
telescope on Hawaii.
703
00:35:00,244 --> 00:35:01,728
The telescope is fine-tuned
704
00:35:01,729 --> 00:35:03,767
to pick out the faint
heat signature
705
00:35:03,777 --> 00:35:05,360
of distant objects
706
00:35:05,361 --> 00:35:08,893
against the cold backdrop
of deep space.
707
00:35:08,894 --> 00:35:11,199
Planet 9 may be frozen.
708
00:35:11,200 --> 00:35:13,119
But it will be
warmer than space.
709
00:35:13,120 --> 00:35:15,424
And that tiny difference
in temperature
710
00:35:15,425 --> 00:35:18,532
is all this incredible
telescope needs.
711
00:35:18,533 --> 00:35:20,680
We want to see
two pictures taken
712
00:35:20,681 --> 00:35:23,283
of the same area of the sky
a few weeks apart.
713
00:35:23,293 --> 00:35:24,905
The stars don't move.
714
00:35:24,906 --> 00:35:27,182
But you see this one, little
thing going, "boop, boop, boop,"
715
00:35:27,183 --> 00:35:28,904
as you flash the pictures
back and forth.
716
00:35:28,905 --> 00:35:30,685
That's what happens
when you have an object
717
00:35:30,686 --> 00:35:32,338
moving around the Sun
718
00:35:32,339 --> 00:35:34,050
against the background of stars.
719
00:35:34,051 --> 00:35:35,970
That's how Pluto was discovered.
720
00:35:35,971 --> 00:35:38,811
That's how we're gonna
find planet 9 if it exists.
721
00:35:40,959 --> 00:35:43,531
It could take years
to find planet 9.
722
00:35:43,532 --> 00:35:45,579
But when we do spot it,
723
00:35:45,580 --> 00:35:48,746
scientists will be able
to analyze its light.
724
00:35:48,747 --> 00:35:51,121
And hidden within
that faint glow
725
00:35:51,122 --> 00:35:53,041
could be the chemical signature
726
00:35:53,042 --> 00:35:56,239
for rock, ice, or gas.
727
00:35:56,249 --> 00:35:59,118
If it is, planet 9's identity
728
00:35:59,119 --> 00:36:03,107
will finally be revealed.
729
00:36:03,117 --> 00:36:06,283
What lies in store beyond that
is a mystery.
730
00:36:06,284 --> 00:36:09,420
But perhaps
the most exciting prospect
731
00:36:09,421 --> 00:36:14,566
is planet 9 could be home
to a family of moons.
732
00:36:14,567 --> 00:36:17,377
And it's just possible
one of these moons
733
00:36:17,378 --> 00:36:19,554
could provide a home for life
734
00:36:19,555 --> 00:36:22,623
100 billion miles from the Sun.
735
00:36:42,050 --> 00:36:44,425
Are we alone in the universe?
736
00:36:47,028 --> 00:36:49,442
For decades,
scientists have scoured
737
00:36:49,443 --> 00:36:51,293
our closest planetary neighbor
738
00:36:51,294 --> 00:36:54,035
for signs of
extraterrestrial life.
739
00:36:56,014 --> 00:36:58,953
But so far, not a trace
has been found.
740
00:37:02,981 --> 00:37:06,247
Is it possible we're targeting
the wrong planet?
741
00:37:10,147 --> 00:37:12,125
If planet 9 is real,
742
00:37:12,126 --> 00:37:15,689
it sits on the icy outer
limits of the solar system.
743
00:37:15,698 --> 00:37:19,815
But even here, 100 billion
miles from the Sun,
744
00:37:19,825 --> 00:37:23,120
it's just possible
that life could thrive
745
00:37:23,121 --> 00:37:25,337
not on the planet itself,
746
00:37:25,338 --> 00:37:28,108
but deep inside its moons.
747
00:37:28,109 --> 00:37:30,424
Historically,
we've always thought of moons
748
00:37:30,425 --> 00:37:32,730
as being these little,
insignificant places.
749
00:37:32,730 --> 00:37:34,382
But the incredible thing
is they may be
750
00:37:34,383 --> 00:37:36,491
the best places to find life.
751
00:37:36,501 --> 00:37:38,045
In our solar system alone,
752
00:37:38,055 --> 00:37:40,587
there may be far more chances
for life on moons of planets
753
00:37:40,588 --> 00:37:43,033
than there are
on planets themselves.
754
00:37:45,052 --> 00:37:47,495
Moons excite astrobiologists
755
00:37:47,496 --> 00:37:51,157
because they can sometimes
support liquid water,
756
00:37:51,158 --> 00:37:53,799
no matter how far
they sit from the Sun.
757
00:37:53,800 --> 00:37:57,036
The key is something
called tidal heating.
758
00:37:59,709 --> 00:38:02,617
Moons on elliptical orbits
get squashed
759
00:38:02,618 --> 00:38:06,051
and squeezed by the gravity
of their parent planet.
760
00:38:06,052 --> 00:38:08,426
This generates heat
and melts ice
761
00:38:08,427 --> 00:38:12,256
to form underground
oceans of liquid water,
762
00:38:12,257 --> 00:38:16,779
the key ingredient
for life as we know it.
763
00:38:16,780 --> 00:38:20,015
If planet 9 is
as big as scientists predict,
764
00:38:20,016 --> 00:38:22,331
it could have multiple moons.
765
00:38:22,332 --> 00:38:24,677
And maybe one of those moons
766
00:38:24,678 --> 00:38:27,180
could have warm, salty oceans
767
00:38:27,181 --> 00:38:30,318
primed for simple life.
768
00:38:30,319 --> 00:38:32,199
So, if you have planet 9,
769
00:38:32,209 --> 00:38:34,019
and it's got icy moons,
and these icy moons
770
00:38:34,020 --> 00:38:36,167
are on the right
kinds of orbits,
771
00:38:36,168 --> 00:38:39,205
the heat could be coming
from within, not without.
772
00:38:39,206 --> 00:38:42,007
And so the Sun basically
doesn't matter.
773
00:38:42,016 --> 00:38:45,479
You could have liquid water
below the surface
774
00:38:45,480 --> 00:38:47,687
that's heated from
the internal geology.
775
00:38:47,697 --> 00:38:49,477
You could have geysers of water
776
00:38:49,478 --> 00:38:50,923
like what we see
coming off of moons
777
00:38:50,933 --> 00:38:52,516
around Saturn and Jupiter.
778
00:38:52,517 --> 00:38:54,852
You could have that all the
way out there at planet 9.
779
00:38:58,494 --> 00:39:03,570
Imagine planet 9
with a system of giant moons.
780
00:39:03,571 --> 00:39:06,351
The closest moon
is heated to melting point
781
00:39:06,352 --> 00:39:09,548
by planet 9's immense gravity.
782
00:39:09,549 --> 00:39:11,072
There's no life here.
783
00:39:11,073 --> 00:39:13,972
Any water boiled away
millions of years ago,
784
00:39:13,982 --> 00:39:16,882
creating a hot,
arid ball of rock.
785
00:39:19,851 --> 00:39:22,492
Farther out lies
a second giant moon.
786
00:39:22,493 --> 00:39:26,887
This new world is encased
in bright, white water ice.
787
00:39:29,500 --> 00:39:31,539
But the crust hides a secret...
788
00:39:31,549 --> 00:39:34,517
a vast ocean
of warm liquid water
789
00:39:34,518 --> 00:39:37,714
heated by volcanic vents
on the ocean floor.
790
00:39:39,931 --> 00:39:43,295
This hidden world is rich
with organic chemistry.
791
00:39:43,296 --> 00:39:48,154
And it could even support
a weird, alien zoo
792
00:39:48,155 --> 00:39:51,192
of pale aquatic creatures.
793
00:39:51,193 --> 00:39:53,469
We associate life with the Sun.
794
00:39:53,470 --> 00:39:56,012
That's how we think of life
originating on the Earth.
795
00:39:56,013 --> 00:39:57,626
But we know
you don't need the Sun.
796
00:39:57,636 --> 00:40:00,170
We have tube worms
at the bottom of the ocean
797
00:40:00,180 --> 00:40:02,158
which live off
of hydrothermal vents.
798
00:40:02,159 --> 00:40:04,198
They get all the chemicals
and the heat they need
799
00:40:04,207 --> 00:40:06,483
from, basically,
the interior of the Earth.
800
00:40:06,484 --> 00:40:08,729
This is not out of the question.
You know, decades ago,
801
00:40:08,730 --> 00:40:10,709
you'd have been laughed
out of a lecture hall
802
00:40:10,709 --> 00:40:12,688
if you'd have said
something like that.
803
00:40:12,689 --> 00:40:14,736
But we have learned
so much about life
804
00:40:14,737 --> 00:40:16,053
in extreme environments
since then
805
00:40:16,054 --> 00:40:18,330
that this is now
in the realm of possibility,
806
00:40:18,340 --> 00:40:19,884
talking about life on a planet
807
00:40:19,894 --> 00:40:21,872
beyond Pluto
in our own solar system.
808
00:40:21,873 --> 00:40:23,455
Wherever there's energy,
809
00:40:23,456 --> 00:40:25,435
wherever there's heat,
there can be life,
810
00:40:25,436 --> 00:40:28,770
even all the way
out by planet 9.
811
00:40:28,771 --> 00:40:30,254
There is good news.
812
00:40:30,255 --> 00:40:33,224
If planet 9 does have
an active watery moon,
813
00:40:33,234 --> 00:40:35,837
we should be able to see it
with our telescopes.
814
00:40:38,153 --> 00:40:40,161
The active moons
of Jupiter and Saturn
815
00:40:40,162 --> 00:40:42,437
are the brightest
in the night sky,
816
00:40:42,438 --> 00:40:46,138
thanks to warm water gushing
out from cracks in the surface
817
00:40:46,139 --> 00:40:51,423
and freezing in bright
white layers of fresh ice.
818
00:40:51,424 --> 00:40:54,324
If planet 9's moons
have liquid oceans,
819
00:40:54,334 --> 00:40:57,500
their surfaces should be
just as bright.
820
00:41:04,893 --> 00:41:08,623
The race is on to image
planet 9 and its moons.
821
00:41:08,624 --> 00:41:12,097
But what we'll see
when those pictures come back
822
00:41:12,098 --> 00:41:13,611
is anybody's guess.
823
00:41:13,612 --> 00:41:15,689
I have to admit, there's
some wonderful tension
824
00:41:15,690 --> 00:41:18,470
that I feel right now when it
comes to finding planet 9.
825
00:41:18,471 --> 00:41:20,015
We have giant telescopes
826
00:41:20,025 --> 00:41:22,261
that are scanning the sky
looking for it.
827
00:41:22,262 --> 00:41:25,665
So, any day now, I'm waiting
with baited breath.
828
00:41:25,666 --> 00:41:26,883
My daughter believes
829
00:41:26,893 --> 00:41:30,158
that planet 9 is pink
with purple dots.
830
00:41:30,159 --> 00:41:32,930
Um, she might be right.
831
00:41:37,324 --> 00:41:38,709
One thing's for sure.
832
00:41:38,710 --> 00:41:41,915
If and when we do find planet 9,
833
00:41:41,916 --> 00:41:46,042
we'll never look at our solar
system the same way again.
834
00:41:46,043 --> 00:41:47,725
This is tremendously exciting,
835
00:41:47,726 --> 00:41:49,902
because, if it's there,
it's already telling us
836
00:41:49,903 --> 00:41:54,494
that there's more to know
about our solar system,
837
00:41:54,495 --> 00:41:57,463
that there are more secrets
literally under the Sun
838
00:41:57,464 --> 00:41:59,908
than we have dreamed of
in our philosophy.
64991
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