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1
00:00:04,860 --> 00:00:07,960
We thought we knew
our solar system.
2
00:00:07,960 --> 00:00:11,560
Turns out we were wrong.
3
00:00:11,560 --> 00:00:13,830
Groundbreaking
observations suggest
4
00:00:13,830 --> 00:00:16,370
an unseen ninth planet
5
00:00:16,370 --> 00:00:21,070
may be out there on the
fringes of our solar system.
6
00:00:21,070 --> 00:00:23,170
And it could be huge,
7
00:00:23,180 --> 00:00:26,540
5,000 times
more massive than Pluto
8
00:00:26,550 --> 00:00:29,210
and 10 times
the mass of the Earth.
9
00:00:29,220 --> 00:00:31,580
We don't get a lot
of revolutions in astronomy.
10
00:00:31,580 --> 00:00:35,520
And here we are on the cusp
of a discovery like this.
11
00:00:35,520 --> 00:00:36,990
It's crazy to think that,
12
00:00:36,990 --> 00:00:38,860
as much as we've looked
into the universe,
13
00:00:38,860 --> 00:00:42,930
that there's this ninth planet
out there that we've never seen.
14
00:00:42,930 --> 00:00:45,930
If planet 9 really is out there,
15
00:00:45,930 --> 00:00:48,270
what will it be like?
16
00:00:48,270 --> 00:00:50,670
Is it a rocky super-Earth,
17
00:00:50,670 --> 00:00:53,070
an icy mega-Pluto,
18
00:00:53,070 --> 00:00:56,310
or a gassy mini-Neptune?
19
00:00:56,310 --> 00:00:59,240
Or is planet 9 an alien world
20
00:00:59,250 --> 00:01:02,050
stolen from another star?
21
00:01:02,050 --> 00:01:05,620
And could it provide
an unlikely home for life
22
00:01:05,620 --> 00:01:09,490
100 billion miles from the Sun?
23
00:01:09,490 --> 00:01:12,560
...Captions by vitac...
www.Vitac.Com
24
00:01:12,560 --> 00:01:15,530
Captions paid for by
Discovery communications
25
00:01:23,670 --> 00:01:25,770
Take a look at the night sky.
26
00:01:25,770 --> 00:01:27,240
The pattern of stars
27
00:01:27,240 --> 00:01:30,570
that drifts overhead
appears fixed.
28
00:01:30,580 --> 00:01:33,680
But look for longer,
weeks or months,
29
00:01:33,680 --> 00:01:38,220
and you'll see a handful
of the points move.
30
00:01:38,220 --> 00:01:41,320
These slow-moving points
of light are the planets,
31
00:01:41,320 --> 00:01:43,520
the giant chunks of rock or gas
32
00:01:43,520 --> 00:01:46,560
that orbit our home star,
the Sun.
33
00:01:46,560 --> 00:01:49,230
We thought there were eight.
34
00:01:49,230 --> 00:01:50,560
We were wrong.
35
00:01:50,560 --> 00:01:52,760
You know, we think
we understand something
36
00:01:52,770 --> 00:01:54,200
as simple as our solar system.
37
00:01:54,200 --> 00:01:56,270
We've found all the planets.
38
00:01:56,270 --> 00:02:00,900
And, right in front of us,
we missed something big.
39
00:02:00,910 --> 00:02:05,340
A group of astronomers are
studying the Kuiper belt,
40
00:02:05,340 --> 00:02:07,740
a vast band of icy asteroids
41
00:02:07,750 --> 00:02:12,350
that sits way, way outside
the orbit of Neptune.
42
00:02:12,350 --> 00:02:15,790
Most of these objects move
in a neat, circular formation
43
00:02:15,790 --> 00:02:17,550
around the Sun.
44
00:02:17,560 --> 00:02:20,760
But the astronomers
are puzzled by a small group
45
00:02:20,760 --> 00:02:22,990
that appear to break the rules,
46
00:02:23,000 --> 00:02:25,830
swinging far outside
the main belt
47
00:02:25,830 --> 00:02:29,470
on wild, extended orbits.
48
00:02:29,470 --> 00:02:32,940
Something sitting far outside
the Kuiper belt
49
00:02:32,940 --> 00:02:36,670
seems to be pulling
these asteroids out of line,
50
00:02:36,680 --> 00:02:40,280
something the size
of a giant planet.
51
00:02:42,350 --> 00:02:44,510
Caltech astronomer
Mike Brown hears
52
00:02:44,520 --> 00:02:46,750
about the wild observations
53
00:02:46,750 --> 00:02:51,120
and is determined to prove
the planet theory wrong.
54
00:02:51,120 --> 00:02:52,360
When we saw
these alignments of all
55
00:02:52,360 --> 00:02:54,190
these objects out there,
we thought,
56
00:02:54,190 --> 00:02:55,730
"ugh, everybody's gonna say
there's a planet.
57
00:02:55,730 --> 00:02:58,860
We have to very strongly prove
there's not a planet."
58
00:02:58,860 --> 00:03:00,500
Because, of course, we all know
59
00:03:00,500 --> 00:03:05,040
there's not another planet
out there. That's ridiculous.
60
00:03:05,040 --> 00:03:08,210
Mike asked his
colleague, Konstantin Batygin,
61
00:03:08,210 --> 00:03:10,070
to run a computer simulation
62
00:03:10,080 --> 00:03:13,010
to see what effect
a ninth planet
63
00:03:13,010 --> 00:03:15,410
should have on the Kuiper belt.
64
00:03:15,410 --> 00:03:17,610
Stunningly,
the simulation predicts
65
00:03:17,620 --> 00:03:20,450
elongated orbits identical
66
00:03:20,450 --> 00:03:22,720
to ones already observed.
67
00:03:22,720 --> 00:03:25,920
But the simulation also
spits out a surprise.
68
00:03:25,920 --> 00:03:29,030
There should be
a second set of rogue orbits
69
00:03:29,030 --> 00:03:31,700
that are perpendicular
to the first set.
70
00:03:31,700 --> 00:03:33,900
If Mike can locate these weird
71
00:03:33,900 --> 00:03:37,330
predicted objects
inside the Kuiper belt,
72
00:03:37,340 --> 00:03:41,440
planet 9 is almost
certainly real.
73
00:03:41,440 --> 00:03:44,810
I took these simulation
results to Mike's office
74
00:03:44,810 --> 00:03:47,480
just a couple doors
down from my office.
75
00:03:47,480 --> 00:03:49,680
And I said, "look!" You know,
"we've got a huge problem!"
76
00:03:49,680 --> 00:03:51,010
He said, "no!"
77
00:03:51,020 --> 00:03:54,550
There's an object
called 2012 dr30
78
00:03:54,550 --> 00:03:58,720
"which has an orbit just like
the one you're predicting."
79
00:03:58,720 --> 00:04:01,790
Mike's asteroid fits
the prediction perfectly.
80
00:04:01,790 --> 00:04:05,830
He searches the records for
more and finds another four
81
00:04:05,830 --> 00:04:08,100
that seem to be
in the right area.
82
00:04:08,100 --> 00:04:12,370
But just how closely
will they fit the prediction?
83
00:04:12,370 --> 00:04:15,340
I remember sitting back
and thinking,
84
00:04:15,340 --> 00:04:18,340
"okay, we're going to,
right now, plot the data,
85
00:04:18,340 --> 00:04:22,550
the real observational data
on top of the model."
86
00:04:22,550 --> 00:04:24,610
And Mike said,
"if these two match up,
87
00:04:24,620 --> 00:04:26,980
my jaw is just gonna
drop to the floor."
88
00:04:26,990 --> 00:04:31,150
The theory says they should be
right here and right here.
89
00:04:31,160 --> 00:04:32,990
And I did the
calculations very quickly
90
00:04:32,990 --> 00:04:36,230
to see where they were
and brought them up.
91
00:04:36,230 --> 00:04:39,860
And there they are.
One, two, three, four, five,
92
00:04:39,870 --> 00:04:41,400
right on these lines
93
00:04:41,400 --> 00:04:44,470
exactly where we predicted
they should be.
94
00:04:44,470 --> 00:04:47,040
The moment we saw this,
95
00:04:47,040 --> 00:04:48,910
we went from cautious
96
00:04:48,910 --> 00:04:51,270
to "holy cow!
This really is there!"
97
00:04:51,280 --> 00:04:53,540
We have to make sure
to tell everybody right away
98
00:04:53,550 --> 00:04:56,250
"because it's actually real!"
99
00:04:56,250 --> 00:04:58,780
Mike and Konstantin had unlocked
100
00:04:58,780 --> 00:05:01,350
the solar system's
greatest secret.
101
00:05:01,350 --> 00:05:05,460
Planet 9 was almost
certainly real.
102
00:05:05,460 --> 00:05:07,090
And it had to be huge,
103
00:05:07,090 --> 00:05:10,330
perhaps 10 times
the mass of Earth.
104
00:05:10,330 --> 00:05:12,730
We're not talking about
something like our moon
105
00:05:12,730 --> 00:05:14,600
or Pluto.
We're talking about something
106
00:05:14,600 --> 00:05:17,770
that is literally
planet-sized.
107
00:05:17,770 --> 00:05:20,370
And we're seeing
its gravitational wake
108
00:05:20,370 --> 00:05:21,710
affecting these other objects.
109
00:05:21,710 --> 00:05:23,840
The idea that there
could be a giant planet
110
00:05:23,840 --> 00:05:25,640
that we've never seen
is something I think
111
00:05:25,640 --> 00:05:27,710
most of people
wouldn't have bet on.
112
00:05:27,710 --> 00:05:30,980
But the evidence is remarkable!
113
00:05:30,980 --> 00:05:33,280
To prove planet 9 exists,
114
00:05:33,290 --> 00:05:36,490
astronomers need to see it
with their telescopes.
115
00:05:36,490 --> 00:05:38,620
But there's a problem.
116
00:05:38,620 --> 00:05:41,360
Computer simulations
only give a broad idea
117
00:05:41,360 --> 00:05:43,490
of where to find it.
118
00:05:43,500 --> 00:05:46,300
And planet 9 is incredibly faint
119
00:05:46,300 --> 00:05:49,500
and almost
inconceivably far away.
120
00:05:49,500 --> 00:05:51,330
It's much, much farther out
121
00:05:51,340 --> 00:05:53,600
than we ever expected
to find planets.
122
00:05:53,610 --> 00:05:55,240
It probably spends
most of its life,
123
00:05:55,240 --> 00:05:56,540
if it's on an elliptical orbit,
124
00:05:56,540 --> 00:05:59,440
so far away from the Sun
that we just missed it.
125
00:06:05,920 --> 00:06:09,620
So just how far away
is planet 9?
126
00:06:09,620 --> 00:06:12,920
The only way to truly
appreciate its vast orbit
127
00:06:12,930 --> 00:06:16,130
is to build a scale model,
128
00:06:16,130 --> 00:06:19,730
perhaps the biggest working
model of the solar system
129
00:06:19,730 --> 00:06:23,030
ever attempted.
130
00:06:23,040 --> 00:06:27,040
Planetary scientist Kevin Walsh
is here to call the shots.
131
00:06:27,040 --> 00:06:30,670
And he starts
with the size of the Sun.
132
00:06:30,680 --> 00:06:33,240
So what we've got here,
our kickball,
133
00:06:33,250 --> 00:06:36,880
is going to set the scale of
our mini-solar system today.
134
00:06:36,880 --> 00:06:40,220
So everything is scaled off
of its relative size
135
00:06:40,220 --> 00:06:43,620
compared to the size of the Sun.
136
00:06:43,620 --> 00:06:45,860
Kevin quickly
paces out the position
137
00:06:45,860 --> 00:06:48,020
of the inner rocky planets.
138
00:06:48,030 --> 00:06:52,660
All four sit within 60 yards
of the Sun on this scale.
139
00:06:52,660 --> 00:06:56,970
And each planet would appear
no bigger than a peppercorn.
140
00:06:56,970 --> 00:06:59,700
To make this
a working solar system,
141
00:06:59,710 --> 00:07:01,610
we need to bring on the drones.
142
00:07:16,150 --> 00:07:19,090
Each drone represents
a different planet.
143
00:07:19,090 --> 00:07:20,490
And the orbital speeds
144
00:07:20,490 --> 00:07:23,290
have been scaled
so one Earth year
145
00:07:23,300 --> 00:07:25,760
takes just 30 seconds.
146
00:07:27,800 --> 00:07:29,230
Already, it's clear to see
147
00:07:29,230 --> 00:07:32,300
how tightly bunched
these inner planets are,
148
00:07:32,300 --> 00:07:34,240
and how the closest planets
149
00:07:34,240 --> 00:07:36,770
orbit faster
than those farther out.
150
00:07:42,250 --> 00:07:45,350
Far beyond the tightly
packed rocky planets
151
00:07:45,350 --> 00:07:48,750
lies the first
of the gas giant planets,
152
00:07:48,750 --> 00:07:52,420
on this scale, just over
a football field from the Sun.
153
00:07:54,560 --> 00:07:57,390
So, after this 400-foot walk,
we made to to Jupiter,
154
00:07:57,400 --> 00:07:59,700
the largest planet
in the solar system.
155
00:07:59,700 --> 00:08:01,000
But, even by this size scale,
156
00:08:01,000 --> 00:08:04,170
Jupiter is only about
the size of a lollipop.
157
00:08:06,200 --> 00:08:08,910
Another football-field
length lies ahead
158
00:08:08,910 --> 00:08:11,610
on the walk to Saturn.
159
00:08:11,610 --> 00:08:14,340
As we look back
across the lake bed,
160
00:08:14,350 --> 00:08:15,780
I can barely see the drones.
161
00:08:15,780 --> 00:08:18,880
We covered a huge distance.
162
00:08:18,880 --> 00:08:21,790
The trek out to Uranus
is bigger still,
163
00:08:21,790 --> 00:08:23,320
three football fields
164
00:08:23,320 --> 00:08:25,690
or the length
of an aircraft carrier.
165
00:08:25,690 --> 00:08:28,790
Turns out there's a lot of wind
in the outer solar system!
166
00:08:28,790 --> 00:08:32,500
So I have to yell.
167
00:08:32,500 --> 00:08:34,830
Surprising amount of wind
in the outer solar system.
168
00:08:37,170 --> 00:08:40,670
Tumbleweed, rattlesnakes.
169
00:08:40,670 --> 00:08:44,840
After Uranus, it's around
200 yards out to Neptune.
170
00:08:44,840 --> 00:08:47,140
Before the discovery
of planet 9,
171
00:08:47,150 --> 00:08:50,650
we thought Neptune was the
farthest planet from the Sun,
172
00:08:50,650 --> 00:08:53,320
around half a mile
on the scale of our model.
173
00:08:53,320 --> 00:08:56,320
But Neptune's distant orbit
is nothing
174
00:08:56,320 --> 00:08:59,690
compared to the orbit
of planet 9.
175
00:08:59,690 --> 00:09:00,890
So here we are.
176
00:09:00,890 --> 00:09:03,030
We made it to
the orbit of Neptune.
177
00:09:03,030 --> 00:09:05,400
We're only at the tip
of the iceberg.
178
00:09:05,400 --> 00:09:07,160
We need to stop
measuring in feet.
179
00:09:07,170 --> 00:09:08,770
And we need to start
thinking in miles.
180
00:09:08,770 --> 00:09:11,370
We need a car
to get out to planet 9.
181
00:09:17,880 --> 00:09:22,150
Planet 9 swings out
on a highly elliptical orbit.
182
00:09:22,150 --> 00:09:24,110
Its closest pass to the Sun
183
00:09:24,120 --> 00:09:27,620
is a whopping 19 billion miles.
184
00:09:27,620 --> 00:09:30,850
That's six times wider
than the orbit of Neptune.
185
00:09:30,860 --> 00:09:33,160
But, at its farthest point,
186
00:09:33,160 --> 00:09:37,790
planet 9
is 112 billion miles away.
187
00:09:37,800 --> 00:09:42,230
And, on this scale,
that's an incredible 18 miles
188
00:09:42,230 --> 00:09:44,970
from our kickball-sized Sun.
189
00:09:44,970 --> 00:09:47,040
So we're here, end of the road.
190
00:09:47,040 --> 00:09:49,110
We've driven about 18 miles
191
00:09:49,110 --> 00:09:51,470
from where we first started
setting up the solar system.
192
00:09:51,480 --> 00:09:53,410
But, in the scale
of the solar system,
193
00:09:53,410 --> 00:09:55,350
it's over 100 billion miles.
194
00:09:55,350 --> 00:09:57,880
100 billion miles
195
00:09:57,880 --> 00:10:01,220
to get out to the furthest
part of planet 9's orbit.
196
00:10:01,220 --> 00:10:02,690
So, to scale,
197
00:10:02,690 --> 00:10:04,950
and we don't know
what planet 9 would look like,
198
00:10:04,960 --> 00:10:08,560
but it's probably about
the size of a B.B.
199
00:10:08,560 --> 00:10:10,790
So this is the challenge
for our astronomers.
200
00:10:10,800 --> 00:10:14,100
How do you see a b.B.
From 18 miles away?
201
00:10:14,100 --> 00:10:16,430
This is what we have to do.
202
00:10:16,440 --> 00:10:18,740
It could take years
for our telescopes
203
00:10:18,740 --> 00:10:22,440
to pick out an object
so impossibly faint,
204
00:10:22,440 --> 00:10:24,640
far away as planet 9.
205
00:10:24,640 --> 00:10:27,740
Until then, scientists
can only speculate
206
00:10:27,750 --> 00:10:31,380
on what this mysterious world
might be like.
207
00:10:31,380 --> 00:10:33,780
We're in this wonderful moment
right now
208
00:10:33,790 --> 00:10:35,490
where we suspect
that planet 9 exists.
209
00:10:35,490 --> 00:10:37,420
But we really have
no idea what it's like.
210
00:10:37,420 --> 00:10:40,420
And that means
our imaginations can run wild.
211
00:10:40,430 --> 00:10:41,960
They're informed by science.
212
00:10:41,960 --> 00:10:44,290
But I love it
when creativity takes hold,
213
00:10:44,300 --> 00:10:45,560
and you just run with it.
214
00:10:47,800 --> 00:10:49,470
So what are the options?
215
00:10:49,470 --> 00:10:52,400
Science suggests
three possibilities.
216
00:10:52,400 --> 00:10:55,210
And the first is astonishing.
217
00:10:55,210 --> 00:10:56,870
Planet 9 could be made
218
00:10:56,880 --> 00:10:59,740
from the same materials
as the Earth,
219
00:10:59,740 --> 00:11:01,910
but 10 times more massive,
220
00:11:01,910 --> 00:11:04,380
a rocky super-Earth.
221
00:11:06,620 --> 00:11:09,490
But what would
this giant, rocky planet
222
00:11:09,490 --> 00:11:12,160
look like so far from the Sun?
223
00:11:12,160 --> 00:11:15,790
A bizarre volcanic world
scarred with fire
224
00:11:15,790 --> 00:11:20,530
somehow emerges from the
cold darkness of deep space.
225
00:11:35,080 --> 00:11:38,950
In 2016, astronomers
release astonishing evidence
226
00:11:38,950 --> 00:11:41,220
of a missing ninth planet
227
00:11:41,220 --> 00:11:43,950
on the frozen edges
of our solar system,
228
00:11:43,960 --> 00:11:48,260
100 billion miles from the Sun.
229
00:11:48,260 --> 00:11:50,030
Until our telescopes find it,
230
00:11:50,030 --> 00:11:54,760
we can only guess what this
mysterious planet 9 is like.
231
00:11:54,770 --> 00:11:58,770
But the first option is
perhaps the most surprising.
232
00:11:58,770 --> 00:12:01,970
Planet 9 could be
made from rock,
233
00:12:01,970 --> 00:12:03,440
just like the Earth,
234
00:12:03,440 --> 00:12:06,240
but 10 times more massive,
235
00:12:06,240 --> 00:12:09,550
a so-called rocky super-Earth.
236
00:12:09,550 --> 00:12:11,710
When we looked out
into the universe, we realized
237
00:12:11,720 --> 00:12:14,420
that the most common
type of planet
238
00:12:14,420 --> 00:12:15,620
in the entire galaxy
239
00:12:15,620 --> 00:12:17,350
is something we don't have,
240
00:12:17,360 --> 00:12:19,760
something called a
super-Earth.
241
00:12:22,860 --> 00:12:26,000
The Kepler space
telescope finds alien worlds
242
00:12:26,000 --> 00:12:28,970
by measuring
the tiny dip in light
243
00:12:28,970 --> 00:12:33,170
as a planet passes
in front of its host star.
244
00:12:33,170 --> 00:12:37,610
Most of the alien solar systems
Kepler finds have super-Earths.
245
00:12:37,610 --> 00:12:41,410
So how come our star
doesn't have one?
246
00:12:41,410 --> 00:12:46,020
Could it be possible that planet
9 is our missing super-Earth?
247
00:12:46,020 --> 00:12:49,190
If planet 9 is
a rocky super-Earth,
248
00:12:49,190 --> 00:12:51,450
what will it look like up close?
249
00:12:57,030 --> 00:13:01,160
Planetary geologist Jani
Radebaugh imagines planet 9
250
00:13:01,170 --> 00:13:06,240
as a dramatic world
of fire and ice.
251
00:13:06,240 --> 00:13:07,440
Right now, we're in Iceland.
252
00:13:07,440 --> 00:13:09,470
We're flying over amazing,
253
00:13:09,470 --> 00:13:12,410
beautiful volcanic landscapes
of Iceland.
254
00:13:12,410 --> 00:13:14,780
We think this might be
the perfect landscape
255
00:13:14,780 --> 00:13:17,850
for thinking about what might
be happening on planet 9
256
00:13:17,850 --> 00:13:21,420
if it's a rocky super-Earth.
257
00:13:21,420 --> 00:13:23,550
These black mountains
and lava flows
258
00:13:23,560 --> 00:13:25,690
were created by leftover heat
259
00:13:25,690 --> 00:13:29,390
from the Earth's formation
spilling out onto the surface.
260
00:13:29,390 --> 00:13:33,530
Planet 9, born with so much
more insulating rock,
261
00:13:33,530 --> 00:13:37,900
should have even more of this
leftover heat trapped inside it.
262
00:13:37,900 --> 00:13:39,200
What we're talking
about is a body
263
00:13:39,200 --> 00:13:42,140
that's maybe 10 times
the mass of the Earth.
264
00:13:42,140 --> 00:13:44,270
I'd expect,
because it's so large,
265
00:13:44,280 --> 00:13:46,410
that we should have lots
more internal heat.
266
00:13:46,410 --> 00:13:48,680
And so, even though it's
far away in the solar system,
267
00:13:48,680 --> 00:13:49,910
it's far away from the Sun,
268
00:13:49,910 --> 00:13:52,120
it's still got lots
of its own energy.
269
00:13:59,160 --> 00:14:02,090
Touching down on
the surface of planet 9,
270
00:14:02,090 --> 00:14:04,590
you'd find a world
as inhospitable
271
00:14:04,600 --> 00:14:08,130
as you could imagine.
272
00:14:08,130 --> 00:14:10,000
Billions of miles from the Sun,
273
00:14:10,000 --> 00:14:12,500
the surface is lit
by little more
274
00:14:12,500 --> 00:14:15,000
than the twinkle
of distant stars
275
00:14:15,010 --> 00:14:18,740
and the red glow of intense
geological activity
276
00:14:18,740 --> 00:14:21,310
on the surface.
277
00:14:21,310 --> 00:14:22,850
We can imagine, if we were on
278
00:14:22,850 --> 00:14:25,150
a super rocky Earth planet 9,
279
00:14:25,150 --> 00:14:28,050
we could have a landscape
just like this one.
280
00:14:28,050 --> 00:14:30,290
There should be volcanoes
erupting all the time.
281
00:14:30,290 --> 00:14:32,020
And the other thing
we should see
282
00:14:32,020 --> 00:14:34,960
is lots and lots of ice and
snow blanketing the landscape.
283
00:14:34,960 --> 00:14:37,930
This is because the atmosphere
is so cold
284
00:14:37,930 --> 00:14:39,700
that parts of it have condensed
285
00:14:39,700 --> 00:14:41,630
and settled back down
onto the surface.
286
00:14:41,630 --> 00:14:44,100
You're gonna have volcanoes.
You're gonna have canyons.
287
00:14:44,100 --> 00:14:46,670
You're gonna have plate
tectonics, mountain-building.
288
00:14:46,670 --> 00:14:49,470
All of these processes are still
gonna be going on out there
289
00:14:49,470 --> 00:14:52,240
in what we normally would
think of as the frozen, cold,
290
00:14:52,240 --> 00:14:54,740
and dead world
of the outer solar system.
291
00:14:58,150 --> 00:15:00,350
As hot lava reaches the surface,
292
00:15:00,350 --> 00:15:03,550
it freezes suddenly
in the cold of space,
293
00:15:03,560 --> 00:15:05,560
perhaps forming a weird,
294
00:15:05,560 --> 00:15:09,290
volcanic glass called obsidian,
295
00:15:09,290 --> 00:15:10,560
another feature shared
296
00:15:10,560 --> 00:15:13,030
with the sub-zero
volcanoes of Iceland.
297
00:15:13,030 --> 00:15:15,900
Okay, let's put
this whole thing together.
298
00:15:15,900 --> 00:15:18,100
We have a landscape
299
00:15:18,100 --> 00:15:20,500
that's kind of dimly lit
by starlight,
300
00:15:20,510 --> 00:15:22,810
but maybe also
by the reddish glow
301
00:15:22,810 --> 00:15:27,480
from erupting lavas spreading
across the landscape.
302
00:15:27,480 --> 00:15:29,750
And then, behind you,
you have gases
303
00:15:29,750 --> 00:15:31,310
that are changing
immediately to snow
304
00:15:31,320 --> 00:15:33,820
and falling as snow
down to the surface.
305
00:15:33,820 --> 00:15:37,250
And it would just be a
beautiful, magical landscape.
306
00:15:40,660 --> 00:15:44,690
The case for a giant, rocky
planet 9 is compelling
307
00:15:44,700 --> 00:15:46,960
because it paints
such a vivid picture
308
00:15:46,970 --> 00:15:50,500
of a living volcanic world.
309
00:15:50,500 --> 00:15:51,970
But there's a problem.
310
00:15:55,540 --> 00:15:58,780
If planet 9
is, in fact, a super-Earth,
311
00:15:58,780 --> 00:16:00,840
how did it form?
Where did it form?
312
00:16:00,850 --> 00:16:02,180
We don't have
any other super-Earths
313
00:16:02,180 --> 00:16:03,410
in our solar system.
314
00:16:03,420 --> 00:16:05,010
And the ones we see
around other stars
315
00:16:05,020 --> 00:16:07,380
are typically really
close to their star.
316
00:16:07,390 --> 00:16:10,520
So how did our super-Earth
end up way out there
317
00:16:10,520 --> 00:16:13,690
at the edges
of our solar system?
318
00:16:13,690 --> 00:16:16,690
For planet 9 to be
our rocky super-Earth,
319
00:16:16,690 --> 00:16:19,760
it would've had to have formed
in the inner solar system
320
00:16:19,760 --> 00:16:22,830
and then migrated out
to its current position.
321
00:16:22,830 --> 00:16:24,630
And that's a problem,
322
00:16:24,640 --> 00:16:28,070
because there probably wasn't
enough rocky material left over
323
00:16:28,070 --> 00:16:29,470
in the early solar system
324
00:16:29,470 --> 00:16:33,110
to create both
the massive planet 9
325
00:16:33,110 --> 00:16:37,510
as well as Mercury, Venus,
Earth, and Mars.
326
00:16:37,520 --> 00:16:38,980
It's really hard to imagine
327
00:16:38,980 --> 00:16:41,820
that we could have formed
a 10-Earth-mass planet here
328
00:16:41,820 --> 00:16:43,690
and still formed
the rocky planets
329
00:16:43,690 --> 00:16:47,060
that we see today.
330
00:16:47,060 --> 00:16:49,260
- '- Time for a new theory.
331
00:16:49,260 --> 00:16:52,400
What if planet 9 formed from ice
332
00:16:52,400 --> 00:16:55,360
in the outer solar system?
333
00:16:55,370 --> 00:16:58,370
Calculations tell us
it would have to be 10 times
334
00:16:58,370 --> 00:16:59,700
the mass of the Earth.
335
00:16:59,700 --> 00:17:01,670
And here's the kicker.
336
00:17:01,670 --> 00:17:03,870
An ice world that big
337
00:17:03,880 --> 00:17:07,940
would have an internal ocean
of liquid water.
338
00:17:07,950 --> 00:17:10,110
A new world is revealed
339
00:17:10,110 --> 00:17:12,680
where icy geysers
shoot through cracks
340
00:17:12,680 --> 00:17:14,280
in the frozen crust.
341
00:17:14,290 --> 00:17:15,690
And deep below it
342
00:17:15,690 --> 00:17:18,120
lies the largest body
of liquid water
343
00:17:18,120 --> 00:17:19,790
in the solar system.
344
00:17:43,380 --> 00:17:45,180
The planets that make up
our solar system
345
00:17:45,180 --> 00:17:48,720
seem to follow a pattern.
346
00:17:48,720 --> 00:17:53,060
The four closest to the Sun
are all made from rock.
347
00:17:53,060 --> 00:17:57,830
The next four are giants
made mostly from gas.
348
00:17:57,830 --> 00:18:00,660
Beyond Neptune, gas is replaced
349
00:18:00,670 --> 00:18:04,070
by multiple worlds
made from ice.
350
00:18:04,070 --> 00:18:05,900
This is the Kuiper belt,
351
00:18:05,900 --> 00:18:09,170
a frozen realm
of water-ice asteroids,
352
00:18:09,170 --> 00:18:11,540
millions of them.
353
00:18:11,540 --> 00:18:14,010
The Kuiper belt
is a region of space
354
00:18:14,010 --> 00:18:15,880
outside of Neptune's orbit
355
00:18:15,880 --> 00:18:17,580
that extends out,
356
00:18:17,580 --> 00:18:20,420
eh, about 50 times the distance
from the Earth to the Sun.
357
00:18:20,420 --> 00:18:22,290
So it's really far out there.
358
00:18:22,290 --> 00:18:24,450
And this is populated
by icy bodies.
359
00:18:24,460 --> 00:18:26,790
These are giant chunks of ice
360
00:18:26,790 --> 00:18:28,790
that have some rock
and other things in them.
361
00:18:28,790 --> 00:18:31,290
But they're mostly ice.
362
00:18:31,300 --> 00:18:34,700
Perhaps planet 9 is
made from the same materials,
363
00:18:34,700 --> 00:18:37,430
an overgrown version
of the Kuiper belt's
364
00:18:37,440 --> 00:18:40,670
most infamous citizen, Pluto.
365
00:18:43,110 --> 00:18:44,640
Poor Pluto.
366
00:18:44,640 --> 00:18:47,710
Discovered in 1930
by Clyde Tombaugh,
367
00:18:47,710 --> 00:18:49,680
this tiny ice world,
368
00:18:49,680 --> 00:18:51,180
smaller than our moon,
369
00:18:51,180 --> 00:18:54,950
was quickly proclaimed
the ninth planet.
370
00:18:54,950 --> 00:18:59,320
But, in the 1990s, Mike brown
and others discovered
371
00:18:59,320 --> 00:19:03,660
a host of icy worlds
orbiting out with Pluto.
372
00:19:03,660 --> 00:19:07,030
Pluto was just another
Kuiper belt object
373
00:19:07,030 --> 00:19:09,500
and got demoted to dwarf planet,
374
00:19:09,500 --> 00:19:12,170
to the dismay
of much of the world.
375
00:19:12,170 --> 00:19:16,570
Everybody loves the idea
that I killed Pluto,
376
00:19:16,570 --> 00:19:19,780
and now I'm trying
to atone for my sins
377
00:19:19,780 --> 00:19:23,280
by replacing it
with a new ninth planet.
378
00:19:23,280 --> 00:19:25,550
In fact, even my daughter
suggested this
379
00:19:25,550 --> 00:19:28,250
long before we started
looking for planet 9.
380
00:19:28,250 --> 00:19:31,420
She said, you know,
"you should find a new planet."
381
00:19:31,420 --> 00:19:33,220
And then you can have
found a planet.
382
00:19:33,220 --> 00:19:35,060
And there'll be
nine planets again.
383
00:19:35,060 --> 00:19:37,230
"And everybody
will like you again."
384
00:19:37,230 --> 00:19:41,430
If planet 9
is an icy Kuiper belt world,
385
00:19:41,430 --> 00:19:45,400
it'll be the biggest
we've ever found.
386
00:19:45,400 --> 00:19:47,640
Pluto, the biggest object
387
00:19:47,640 --> 00:19:49,610
we know out there
in the Kuiper belt now,
388
00:19:49,610 --> 00:19:52,170
is less than 1%
the mass of the Earth,
389
00:19:52,180 --> 00:19:53,710
less than that.
390
00:19:53,710 --> 00:19:56,550
Planet 9, we think, is 10
times the mass of the Earth.
391
00:19:56,550 --> 00:19:59,920
So we're dealing with a factor
of thousands of times in mass
392
00:19:59,920 --> 00:20:02,390
between the largest
Kuiper belt object
393
00:20:02,390 --> 00:20:04,220
that we know now
394
00:20:04,220 --> 00:20:06,720
and the size of planet 9.
395
00:20:06,720 --> 00:20:10,790
So you're talking about
super-mega-ultra-Pluto.
396
00:20:10,800 --> 00:20:12,700
It's really, really big.
397
00:20:12,700 --> 00:20:15,870
And it's hard to know
what an ice ball
398
00:20:15,870 --> 00:20:18,170
like that would look like.
399
00:20:18,170 --> 00:20:22,170
It's not crazy to speculate that
there could still be activity,
400
00:20:22,170 --> 00:20:23,810
internal geologic activity,
401
00:20:23,810 --> 00:20:26,410
keeping this world
from being cold
402
00:20:26,410 --> 00:20:29,010
and totally dead.
403
00:20:29,010 --> 00:20:30,750
Peering through the darkness
404
00:20:30,750 --> 00:20:34,550
to a hypothetical
mega-Pluto planet 9,
405
00:20:34,550 --> 00:20:37,820
we discover
a giant world of ice.
406
00:20:37,820 --> 00:20:41,260
There's much less rock
than a super-Earth planet 9.
407
00:20:41,260 --> 00:20:44,330
But the mass of ice alone
creates enough gravity
408
00:20:44,330 --> 00:20:49,270
to generate warmth deep in
the core, even out here.
409
00:20:49,270 --> 00:20:53,100
The real currency of keeping
a planet alive is mass.
410
00:20:53,100 --> 00:20:56,040
Does it have enough mass
to keep the interior warm?
411
00:20:56,040 --> 00:20:57,910
Well, something
that's 5 to 10 times
412
00:20:57,910 --> 00:21:02,450
the mass of the Earth
probably would be warm inside.
413
00:21:02,450 --> 00:21:06,680
Up close, the surface
explodes with activity.
414
00:21:06,680 --> 00:21:11,550
But these volcanoes
spew water ice, not lava.
415
00:21:11,560 --> 00:21:13,790
If something like
a giant Pluto exists,
416
00:21:13,790 --> 00:21:15,760
it must be the most
amazing landscape
417
00:21:15,760 --> 00:21:17,160
to take a walk over.
418
00:21:17,160 --> 00:21:20,630
You'd have these ice volcanoes
spewing out jets
419
00:21:20,630 --> 00:21:23,630
of frozen water,
of ice raining down on you.
420
00:21:23,630 --> 00:21:25,430
Maybe you'd look out
over the landscape
421
00:21:25,440 --> 00:21:27,900
and see hundreds
of these erupting.
422
00:21:27,910 --> 00:21:31,270
This dramatic,
icy vista is a gateway
423
00:21:31,280 --> 00:21:33,080
to a secret world,
424
00:21:33,080 --> 00:21:36,110
a vast, slushy ocean
of liquid water
425
00:21:36,110 --> 00:21:38,110
mixed with ice crystals,
426
00:21:38,120 --> 00:21:39,580
perhaps the largest
427
00:21:39,580 --> 00:21:42,220
single body of water
in the solar system.
428
00:21:42,220 --> 00:21:44,450
There's gonna be enough
internal heat, maybe,
429
00:21:44,460 --> 00:21:47,590
to turn this
into a slushy water world.
430
00:21:47,590 --> 00:21:50,490
So it's not quite
a terrestrial, rocky planet.
431
00:21:50,500 --> 00:21:53,000
And it's not
a Uranus or Neptune.
432
00:21:53,000 --> 00:21:56,030
It's a true mega-ocean world,
433
00:21:56,030 --> 00:21:59,970
but perhaps a very cold one.
434
00:21:59,970 --> 00:22:03,540
Is planet 9 an icy mega-Pluto?
435
00:22:03,540 --> 00:22:05,470
The problem is scale.
436
00:22:05,480 --> 00:22:09,580
Pluto and the other objects
in the Kuiper belt are tiny.
437
00:22:09,580 --> 00:22:12,110
So how could the same
building materials
438
00:22:12,120 --> 00:22:16,220
have come together
to form a giant?
439
00:22:16,220 --> 00:22:18,150
So, the idea that planet 9
440
00:22:18,160 --> 00:22:22,560
is simply a really scaled-up
Pluto, a mega-Pluto,
441
00:22:22,560 --> 00:22:24,230
has some difficulties.
442
00:22:24,230 --> 00:22:27,930
We just don't think that there
was enough mass out there
443
00:22:27,930 --> 00:22:29,800
in the far reaches
of the solar system
444
00:22:29,800 --> 00:22:32,230
to all come together
to build a planet that large.
445
00:22:32,240 --> 00:22:34,240
When you look
at the Kuiper belt,
446
00:22:34,240 --> 00:22:36,140
there are all of these
small, icy bodies.
447
00:22:36,140 --> 00:22:38,170
There's nothing
very big out there.
448
00:22:38,180 --> 00:22:40,240
And we think that's not
a coincidence,
449
00:22:40,240 --> 00:22:42,480
that the disk of dust and gas
that formed the planets
450
00:22:42,480 --> 00:22:44,680
had more stuff
closer to the Sun.
451
00:22:44,680 --> 00:22:46,620
And by the time you got out
to where Pluto is,
452
00:22:46,620 --> 00:22:49,350
there wasn't much material
to build planets out of,
453
00:22:49,350 --> 00:22:50,690
certainly not a planet
454
00:22:50,690 --> 00:22:55,090
5 to 10 times
the mass of the Earth.
455
00:22:55,090 --> 00:22:59,760
So, if planet 9 didn't form
in the icy outer system
456
00:22:59,760 --> 00:23:03,430
and didn't form in the rocky,
inner solar system,
457
00:23:03,430 --> 00:23:05,370
where did it come from?
458
00:23:05,370 --> 00:23:07,400
The more likely option,
459
00:23:07,410 --> 00:23:10,410
planet 9 formed
in the gas-rich zone
460
00:23:10,410 --> 00:23:12,540
in the middle
of our solar system
461
00:23:12,540 --> 00:23:16,850
that also created Jupiter,
Saturn, and Neptune.
462
00:23:16,850 --> 00:23:19,920
A gassy planet 9
could be similar to Neptune,
463
00:23:19,920 --> 00:23:23,390
but perhaps a little smaller,
464
00:23:23,390 --> 00:23:25,320
a mini-Neptune.
465
00:23:25,320 --> 00:23:27,960
But how would it get
so much farther out
466
00:23:27,960 --> 00:23:29,860
than the other gas giants?
467
00:23:29,860 --> 00:23:32,830
And what would it look like?
468
00:23:32,830 --> 00:23:36,100
Imagine a weird,
translucent world
469
00:23:36,100 --> 00:23:40,300
glowing in the dark like a
giant deep-sea creature.
470
00:23:57,960 --> 00:24:00,420
Something on the fringes
of our solar system
471
00:24:00,420 --> 00:24:03,890
is upsetting orbits
and causing a ruckus.
472
00:24:03,900 --> 00:24:06,730
Could it be a planet?
473
00:24:06,730 --> 00:24:08,860
It's incredible to me
that we now know
474
00:24:08,870 --> 00:24:10,500
of thousands of other planets
475
00:24:10,500 --> 00:24:12,570
going around other stars
in the sky,
476
00:24:12,570 --> 00:24:15,370
but we may have
missed a big planet
477
00:24:15,370 --> 00:24:17,510
in our own solar system.
478
00:24:17,510 --> 00:24:21,240
Planet 9, a world
we know almost nothing about,
479
00:24:21,250 --> 00:24:25,250
beyond the possibility
that it exists.
480
00:24:25,250 --> 00:24:29,990
Science suggests
intriguing options...
481
00:24:29,990 --> 00:24:33,420
a giant, rocky world
with a heart of fire,
482
00:24:33,420 --> 00:24:36,090
or an ice world filled
483
00:24:36,090 --> 00:24:39,130
with a giant, slushy ocean.
484
00:24:39,130 --> 00:24:43,530
But problems with each theory
have led to new hunches.
485
00:24:43,530 --> 00:24:46,540
So, if it's not a rocky,
metallic super-Earth
486
00:24:46,540 --> 00:24:50,740
and it's not a gigantic,
ice-ball, mega-Pluto,
487
00:24:50,740 --> 00:24:52,240
what's left?
488
00:24:52,240 --> 00:24:54,910
And the answer is a gas giant.
489
00:24:54,910 --> 00:24:59,150
And that strikes me as being
the most likely prospect.
490
00:24:59,150 --> 00:25:02,350
When you think about
the mass of planet 9
491
00:25:02,350 --> 00:25:05,220
and where it is now,
my best guess,
492
00:25:05,220 --> 00:25:10,030
it's something like a
miniature version of Neptune.
493
00:25:10,030 --> 00:25:11,960
The gas giant planets
494
00:25:11,960 --> 00:25:14,960
are the monsters
of our solar system.
495
00:25:14,970 --> 00:25:17,430
Instead of a solid surface,
like the Earth,
496
00:25:17,440 --> 00:25:20,970
the gas giants have thick,
stormy atmospheres
497
00:25:20,970 --> 00:25:24,110
that descend for tens
of thousands of miles,
498
00:25:24,110 --> 00:25:26,980
shrouding their small,
rocky cores.
499
00:25:29,180 --> 00:25:31,710
Jupiter is
the largest gas giant,
500
00:25:31,720 --> 00:25:35,380
over 300 times
the mass of Earth.
501
00:25:35,390 --> 00:25:36,690
Moving out from Jupiter,
502
00:25:36,690 --> 00:25:40,220
the gas giants
get progressively smaller,
503
00:25:40,220 --> 00:25:44,190
Saturn, then Uranus,
and finally Neptune,
504
00:25:44,200 --> 00:25:48,060
around 17 times
the mass of the Earth.
505
00:25:48,070 --> 00:25:50,930
If planet 9 is a gas giant,
506
00:25:50,940 --> 00:25:53,000
it'll be even smaller,
507
00:25:53,000 --> 00:25:55,170
a mini-Neptune.
508
00:25:55,170 --> 00:25:57,370
If planet 9 is a mini-Neptune,
509
00:25:57,380 --> 00:25:59,210
if it's a lot like Neptune,
510
00:25:59,210 --> 00:26:01,040
then it's not really like
511
00:26:01,050 --> 00:26:02,580
a terrestrial planet,
like Earth.
512
00:26:02,580 --> 00:26:05,150
But it's not really like
a gas giant, like Jupiter.
513
00:26:05,150 --> 00:26:07,480
Neptune is this weird,
in-between thing
514
00:26:07,490 --> 00:26:09,890
where it's probably got
a rocky core.
515
00:26:09,890 --> 00:26:12,790
But it's actually, mostly,
what astronomers call ices.
516
00:26:12,790 --> 00:26:16,430
It's got methane in it and water
and various other substances
517
00:26:16,430 --> 00:26:19,560
and a very, very, very thick
atmosphere on top of that.
518
00:26:24,070 --> 00:26:26,800
Neptune's thick clouds
are stained blue
519
00:26:26,800 --> 00:26:28,940
with molecules of methane.
520
00:26:28,940 --> 00:26:33,610
But planet 9's atmosphere
could be transparent.
521
00:26:33,610 --> 00:26:36,650
It's so cold out there,
you're getting almost
522
00:26:36,650 --> 00:26:38,750
no extra energy from the Sun.
523
00:26:38,750 --> 00:26:40,650
And so then anything
heavy in the atmosphere,
524
00:26:40,650 --> 00:26:42,720
any heavier molecule, over time,
525
00:26:42,720 --> 00:26:44,790
would have probably
fallen to the surface.
526
00:26:44,790 --> 00:26:46,720
And only the lightest elements,
527
00:26:46,720 --> 00:26:49,690
the lightest molecules,
would stay in your atmosphere,
528
00:26:49,690 --> 00:26:52,860
so maybe just almost
pure hydrogen or helium.
529
00:26:52,860 --> 00:26:56,230
And you'd have, maybe,
a really clear atmosphere.
530
00:26:56,230 --> 00:26:58,300
What would
a mini-Neptune look like
531
00:26:58,300 --> 00:27:00,000
that far out from the Sun?
532
00:27:00,000 --> 00:27:02,600
The thing I think of are
things like jellyfish, right?
533
00:27:02,610 --> 00:27:04,340
That sort of beautiful,
translucent look,
534
00:27:04,340 --> 00:27:07,710
where you're looking through to
the innards of the organism.
535
00:27:07,710 --> 00:27:09,180
In this case,
you might look through
536
00:27:09,180 --> 00:27:12,610
to the innards
of the planet in some way.
537
00:27:12,620 --> 00:27:15,180
The atmosphere
may be transparent.
538
00:27:15,190 --> 00:27:17,890
But this planet
is far from calm.
539
00:27:17,890 --> 00:27:21,420
The interior is lit by
the flash of thunderstorms.
540
00:27:21,430 --> 00:27:24,090
And faint lights
dance around the poles
541
00:27:24,100 --> 00:27:26,700
as solar winds
from distant stars
542
00:27:26,700 --> 00:27:29,670
stream down the planet's
magnetic fields.
543
00:27:29,670 --> 00:27:31,700
Looking into the
innards of the planet,
544
00:27:31,700 --> 00:27:34,300
it would look, in some ways,
like these gorgeous,
545
00:27:34,310 --> 00:27:38,310
beautiful deep-sea organisms
that are bioluminescent.
546
00:27:38,310 --> 00:27:40,280
And we may have
the planetary equivalent
547
00:27:40,280 --> 00:27:43,080
of something like out there in
the inky blackness of space,
548
00:27:43,080 --> 00:27:47,450
rather than the inky blackness
of the deep ocean.
549
00:27:47,450 --> 00:27:50,550
Could planet 9
be a mini-Neptune?
550
00:27:50,550 --> 00:27:54,160
Surprisingly, the possibility
of an extra gas giant
551
00:27:54,160 --> 00:27:57,260
in our solar system isn't new.
552
00:27:57,260 --> 00:27:59,860
In 2011, scientists attempted
553
00:27:59,860 --> 00:28:01,130
to replicate the formation
554
00:28:01,130 --> 00:28:04,500
of our solar system
using supercomputers.
555
00:28:04,500 --> 00:28:06,570
But their models didn't work
556
00:28:06,570 --> 00:28:12,040
unless they added an extra
gas giant planet to the mix.
557
00:28:12,040 --> 00:28:14,240
It was really
difficult to reproduce
558
00:28:14,250 --> 00:28:16,350
our current solar system.
559
00:28:16,350 --> 00:28:18,150
But one scientist found that,
560
00:28:18,150 --> 00:28:21,020
if you add a fifth large planet
561
00:28:21,020 --> 00:28:22,420
to our solar system,
562
00:28:22,420 --> 00:28:25,090
then that planet will end up
563
00:28:25,090 --> 00:28:27,320
getting ejected
from our solar system.
564
00:28:27,320 --> 00:28:30,260
And you'd have the planets
that we have today.
565
00:28:32,200 --> 00:28:34,630
Is planet 9
the missing gas giant
566
00:28:34,630 --> 00:28:37,370
predicted by the supercomputers?
567
00:28:37,370 --> 00:28:39,670
The computer model
shows it being ejected
568
00:28:39,670 --> 00:28:42,100
by the immense gravity
of Jupiter.
569
00:28:42,110 --> 00:28:46,440
But did planet 9 instead
cling to our solar system
570
00:28:46,440 --> 00:28:50,150
by the tips of its
gravitational fingers?
571
00:28:50,150 --> 00:28:51,850
Sometimes,
our mathematical models
572
00:28:51,850 --> 00:28:53,750
predict things
that we think are impossible.
573
00:28:53,750 --> 00:28:55,320
And then we find them.
574
00:28:55,320 --> 00:28:56,990
And, for a while,
we've known that,
575
00:28:56,990 --> 00:28:58,490
if you throw a mini-Neptune
576
00:28:58,490 --> 00:29:00,620
into the mix of planets forming,
577
00:29:00,620 --> 00:29:02,160
the models work better.
578
00:29:02,160 --> 00:29:06,030
Maybe we found that key,
finally... planet 9.
579
00:29:06,030 --> 00:29:09,200
We know giant planets
can get thrown around.
580
00:29:09,200 --> 00:29:11,830
Observers have even seen
ejected planets
581
00:29:11,840 --> 00:29:15,500
floating free in the space
between stars.
582
00:29:15,510 --> 00:29:19,610
Did planet 9 almost
suffer the same fate?
583
00:29:19,610 --> 00:29:22,280
It's entirely possible
that there could've been
584
00:29:22,280 --> 00:29:23,710
a planet forming
bigger than Earth,
585
00:29:23,710 --> 00:29:25,750
something like a super-Earth,
well on its way
586
00:29:25,750 --> 00:29:27,280
to becoming a gas giant
587
00:29:27,280 --> 00:29:30,320
in this wonderful area
of the disk,
588
00:29:30,320 --> 00:29:32,090
where it could've drawn in
a lot of material
589
00:29:32,090 --> 00:29:34,160
and become a gas giant
like Jupiter,
590
00:29:34,160 --> 00:29:36,530
except it got
too close to Jupiter.
591
00:29:36,530 --> 00:29:38,060
And, before it could do that,
592
00:29:38,060 --> 00:29:40,360
it was gravitationally
thrown away
593
00:29:40,360 --> 00:29:42,700
from this wonderful
feeding ground
594
00:29:42,700 --> 00:29:44,570
out into the much sparser,
595
00:29:44,570 --> 00:29:47,470
more barren desert
of the outer solar system.
596
00:29:50,440 --> 00:29:53,840
Is planet 9 really
a frozen mini-Neptune
597
00:29:53,840 --> 00:29:57,310
banished to the badlands
of the outer solar system?
598
00:29:57,310 --> 00:30:00,020
Right now, it's our best bet.
599
00:30:00,020 --> 00:30:02,750
But there is one more option.
600
00:30:02,750 --> 00:30:04,590
Some scientists believe
601
00:30:04,590 --> 00:30:08,420
planet 9 may not have formed
around our Sun at all.
602
00:30:11,800 --> 00:30:14,030
Is our most distant planet
603
00:30:14,030 --> 00:30:17,600
an alien world snatched
from another star?
604
00:30:37,590 --> 00:30:40,390
If the mysterious
planet 9 exists,
605
00:30:40,390 --> 00:30:42,920
it is by far
the most distant planet
606
00:30:42,930 --> 00:30:44,330
in the solar system,
607
00:30:44,330 --> 00:30:47,200
20 times farther out
than Neptune.
608
00:30:47,200 --> 00:30:49,770
So how did it get there?
609
00:30:49,770 --> 00:30:53,540
Was it made in the place
it currently occupies?
610
00:30:53,540 --> 00:30:56,170
Or was it flung out
from the inner solar system
611
00:30:56,170 --> 00:30:57,710
as a rocky super-Earth
612
00:30:57,710 --> 00:31:01,180
or, more likely, a
mini-Neptune?
613
00:31:01,180 --> 00:31:02,880
The jury's out.
614
00:31:02,880 --> 00:31:05,810
But there is another option.
615
00:31:05,820 --> 00:31:07,620
And it's out of this world.
616
00:31:07,620 --> 00:31:10,350
So the question is, then,
where did it come from
617
00:31:10,350 --> 00:31:11,820
if neither of these things
is right?
618
00:31:11,820 --> 00:31:15,390
And it's possible that
there is another explanation.
619
00:31:15,390 --> 00:31:19,260
And that is that planet 9
is an alien visitor
620
00:31:19,260 --> 00:31:21,100
from outer space.
621
00:31:24,070 --> 00:31:27,540
The Sun is just 1
of 200 billion stars
622
00:31:27,540 --> 00:31:30,210
orbiting the supermassive
black hole
623
00:31:30,210 --> 00:31:33,310
at the center
of the milky way galaxy.
624
00:31:33,310 --> 00:31:36,780
Most of these stars probably
have multiple planets.
625
00:31:36,780 --> 00:31:40,350
And scientists now believe
that, from time to time,
626
00:31:40,350 --> 00:31:44,350
two stars might pass a little
too close for comfort.
627
00:31:44,360 --> 00:31:48,820
The result... planetary theft.
628
00:31:48,830 --> 00:31:51,060
We know that the Sun moves
around in the galaxy.
629
00:31:51,060 --> 00:31:52,660
We know that there
are other stars
630
00:31:52,660 --> 00:31:53,860
and other solar systems.
631
00:31:53,860 --> 00:31:56,600
Is it possible that
the Sun passed so close
632
00:31:56,600 --> 00:31:57,900
to another solar system
633
00:31:57,900 --> 00:32:01,470
that it stole a planet?
634
00:32:01,470 --> 00:32:04,370
Today, our Sun
drifts through space alone,
635
00:32:04,380 --> 00:32:07,340
like a yacht in the open ocean.
636
00:32:07,340 --> 00:32:09,680
But that wasn't always the case.
637
00:32:09,680 --> 00:32:12,950
Rewind the clock
4.6 billion years,
638
00:32:12,950 --> 00:32:17,220
and our local star cluster
was a much more crowded place,
639
00:32:17,220 --> 00:32:21,120
ideal conditions
for planet 9 to jump ship.
640
00:32:23,160 --> 00:32:25,030
The Sun was born in a nursery
641
00:32:25,030 --> 00:32:27,130
with thousands of other stars.
642
00:32:27,130 --> 00:32:29,000
Just like the boats
in this harbor,
643
00:32:29,000 --> 00:32:32,170
there are so many boats
around, so many neighbors.
644
00:32:32,170 --> 00:32:34,100
It was like that
for the young Sun.
645
00:32:36,070 --> 00:32:39,540
Stars like the Sun
are born in stellar nurseries,
646
00:32:39,540 --> 00:32:41,940
vast clouds of gas that collapse
647
00:32:41,950 --> 00:32:44,880
to form tens of thousands
of stars,
648
00:32:44,880 --> 00:32:47,250
all tightly packed together.
649
00:32:49,250 --> 00:32:51,350
Astronomers think it's possible
650
00:32:51,360 --> 00:32:55,560
that, inside this cramped,
confused playground of stars,
651
00:32:55,560 --> 00:32:58,830
our Sun's gravity
could've stolen planet 9
652
00:32:58,830 --> 00:33:00,800
from a passing neighbor.
653
00:33:00,800 --> 00:33:02,530
Imagine this cool scenario.
654
00:33:02,530 --> 00:33:04,530
You've got an alien star.
655
00:33:04,540 --> 00:33:06,700
And around that star
forms a planet.
656
00:33:06,700 --> 00:33:08,100
This is planet 9.
657
00:33:08,110 --> 00:33:10,170
And here comes the Sun
whizzing by.
658
00:33:10,170 --> 00:33:12,940
The Sun gets so close
that it steals planet 9
659
00:33:12,940 --> 00:33:16,650
on its way out into the galaxy.
660
00:33:16,650 --> 00:33:18,950
It sounds like science fiction.
661
00:33:18,950 --> 00:33:23,080
But our Sun may already
have a criminal record.
662
00:33:23,090 --> 00:33:26,420
There's some evidence that
the comets in our solar system
663
00:33:26,420 --> 00:33:28,520
may not have started
in our solar system.
664
00:33:28,530 --> 00:33:31,690
We may have stolen comets
from other stars.
665
00:33:31,700 --> 00:33:33,230
If that's the case,
666
00:33:33,230 --> 00:33:34,860
it's not totally outrageous
667
00:33:34,870 --> 00:33:38,700
to think that a planet that
formed around another star
668
00:33:38,700 --> 00:33:41,500
somehow made its way
into our solar system
669
00:33:41,510 --> 00:33:45,010
and became part of our family.
670
00:33:45,010 --> 00:33:47,810
But if planet 9 really did
come from another star,
671
00:33:47,810 --> 00:33:51,280
how will we know for sure
that it's an alien visitor?
672
00:33:51,280 --> 00:33:53,250
What we'd like to do
is essentially
673
00:33:53,250 --> 00:33:55,650
a DNA test on planet 9,
674
00:33:55,650 --> 00:33:57,620
scoop up some of its surface
675
00:33:57,620 --> 00:34:01,620
and look for material
that we absolutely know
676
00:34:01,630 --> 00:34:03,330
couldn't have formed
around our Sun,
677
00:34:03,330 --> 00:34:05,730
because we don't see it anywhere
else in our solar system.
678
00:34:05,730 --> 00:34:07,660
We may even have
to send a probe there
679
00:34:07,660 --> 00:34:09,400
to really get a good look at it
680
00:34:09,400 --> 00:34:11,700
and find out what
its chemical composition is,
681
00:34:11,700 --> 00:34:14,740
exactly everything we can
find out about its orbit.
682
00:34:14,740 --> 00:34:16,170
And, that way,
we might be able to see
683
00:34:16,170 --> 00:34:19,070
if there are any
sort of fingerprints,
684
00:34:19,080 --> 00:34:21,240
smoking-gun pieces of evidence
685
00:34:21,250 --> 00:34:24,210
that'll say clearly
this formed here
686
00:34:24,210 --> 00:34:26,550
or it formed out there.
687
00:34:30,220 --> 00:34:34,390
Unfortunately, before we can
688
00:34:34,390 --> 00:34:38,190
we first have to find it.
689
00:34:38,200 --> 00:34:39,660
Astronomers like Mike brown
690
00:34:39,660 --> 00:34:41,860
have made the challenge
a little easier,
691
00:34:41,870 --> 00:34:45,400
using math
to narrow down the zone.
692
00:34:45,400 --> 00:34:47,840
What we know right now
is that planet 9
693
00:34:47,840 --> 00:34:50,970
is in a swath of the sky
that goes about like this.
694
00:34:50,970 --> 00:34:53,310
It's about this big.
It goes across like this.
695
00:34:53,310 --> 00:34:55,580
But we think we even know
a little bit better.
696
00:34:55,580 --> 00:34:57,980
We've pinpointed, or at least
slightly constrained
697
00:34:57,980 --> 00:35:01,580
where it is, to a patch of sky
that's about this big.
698
00:35:01,590 --> 00:35:03,320
It's still a lot of sky
to look at.
699
00:35:03,320 --> 00:35:07,420
But it's a lot less than having
to look at the whole sky.
700
00:35:07,420 --> 00:35:12,090
Mike's patch of sky is close
701
00:35:12,100 --> 00:35:13,530
he's going to wait until fall,
702
00:35:13,530 --> 00:35:15,460
when Orion is highest
in the sky,
703
00:35:15,470 --> 00:35:17,300
to search for planet 9
704
00:35:17,300 --> 00:35:22,100
using the Subaru infrared
telescope on Hawaii.
705
00:35:22,110 --> 00:35:23,610
The telescope is fine-tuned
706
00:35:23,610 --> 00:35:25,670
to pick out the faint
heat signature
707
00:35:25,680 --> 00:35:27,280
of distant objects
708
00:35:27,280 --> 00:35:30,850
against the cold backdrop
of deep space.
709
00:35:30,850 --> 00:35:33,180
Planet 9 may be frozen.
710
00:35:33,180 --> 00:35:35,120
But it will be
warmer than space.
711
00:35:35,120 --> 00:35:37,450
And that tiny difference
in temperature
712
00:35:37,450 --> 00:35:40,590
is all this incredible
telescope needs.
713
00:35:40,590 --> 00:35:42,760
We want to see
two pictures taken
714
00:35:42,760 --> 00:35:45,390
of the same area of the sky
a few weeks apart.
715
00:35:45,400 --> 00:35:47,030
The stars don't move.
716
00:35:47,030 --> 00:35:49,330
But you see this one, little
thing going, "boop, boop, boop,"
717
00:35:49,330 --> 00:35:51,070
as you flash the pictures
back and forth.
718
00:35:51,070 --> 00:35:52,870
That's what happens
when you have an object
719
00:35:52,870 --> 00:35:54,540
moving around the Sun
720
00:35:54,540 --> 00:35:56,270
against the background of stars.
721
00:35:56,270 --> 00:35:58,210
That's how Pluto was discovered.
722
00:35:58,210 --> 00:36:01,080
That's how we're gonna
find planet 9 if it exists.
723
00:36:03,250 --> 00:36:05,850
It could take years
to find planet 9.
724
00:36:05,850 --> 00:36:07,920
But when we do spot it,
725
00:36:07,920 --> 00:36:11,120
scientists will be able
to analyze its light.
726
00:36:11,120 --> 00:36:13,520
And hidden within
that faint glow
727
00:36:13,520 --> 00:36:15,460
could be the chemical signature
728
00:36:15,460 --> 00:36:18,690
for rock, ice, or gas.
729
00:36:18,700 --> 00:36:21,600
If it is, planet 9's identity
730
00:36:21,600 --> 00:36:25,630
will finally be revealed.
731
00:36:25,640 --> 00:36:28,840
What lies in store beyond that
is a mystery.
732
00:36:28,840 --> 00:36:32,010
But perhaps
the most exciting prospect
733
00:36:32,010 --> 00:36:37,210
is planet 9 could be home
to a family of moons.
734
00:36:37,210 --> 00:36:40,050
And it's just possible
one of these moons
735
00:36:40,050 --> 00:36:42,250
could provide a home for life
736
00:36:42,250 --> 00:36:45,350
100 billion miles from the Sun.
737
00:37:04,980 --> 00:37:07,380
Are we alone in the universe?
738
00:37:10,010 --> 00:37:12,450
For decades,
scientists have scoured
739
00:37:12,450 --> 00:37:14,320
our closest planetary neighbor
740
00:37:14,320 --> 00:37:17,090
for signs of
extraterrestrial life.
741
00:37:19,090 --> 00:37:22,060
But so far, not a trace
has been found.
742
00:37:26,130 --> 00:37:29,430
Is it possible we're targeting
the wrong planet?
743
00:37:33,370 --> 00:37:35,370
If planet 9 is real,
744
00:37:35,370 --> 00:37:38,970
it sits on the icy outer
limits of the solar system.
745
00:37:38,980 --> 00:37:43,140
But even here, 100 billion
miles from the Sun,
746
00:37:43,150 --> 00:37:46,480
it's just possible
that life could thrive
747
00:37:46,480 --> 00:37:48,720
not on the planet itself,
748
00:37:48,720 --> 00:37:51,520
but deep inside its moons.
749
00:37:51,520 --> 00:37:53,860
Historically,
we've always thought of moons
750
00:37:53,860 --> 00:37:56,190
as being these little,
insignificant places.
751
00:37:56,190 --> 00:37:57,860
But the incredible thing
is they may be
752
00:37:57,860 --> 00:37:59,990
the best places to find life.
753
00:38:00,000 --> 00:38:01,560
In our solar system alone,
754
00:38:01,570 --> 00:38:04,130
there may be far more chances
for life on moons of planets
755
00:38:04,130 --> 00:38:06,600
than there are
on planets themselves.
756
00:38:08,640 --> 00:38:11,110
Moons excite astrobiologists
757
00:38:11,110 --> 00:38:14,810
because they can sometimes
support liquid water,
758
00:38:14,810 --> 00:38:17,480
no matter how far
they sit from the Sun.
759
00:38:17,480 --> 00:38:20,750
The key is something
called tidal heating.
760
00:38:23,450 --> 00:38:26,390
Moons on elliptical orbits
get squashed
761
00:38:26,390 --> 00:38:29,860
and squeezed by the gravity
of their parent planet.
762
00:38:29,860 --> 00:38:32,260
This generates heat
and melts ice
763
00:38:32,260 --> 00:38:36,130
to form underground
oceans of liquid water,
764
00:38:36,130 --> 00:38:40,700
the key ingredient
for life as we know it.
765
00:38:40,700 --> 00:38:43,970
If planet 9 is
as big as scientists predict,
766
00:38:43,970 --> 00:38:46,310
it could have multiple moons.
767
00:38:46,310 --> 00:38:48,680
And maybe one of those moons
768
00:38:48,680 --> 00:38:51,210
could have warm, salty oceans
769
00:38:51,210 --> 00:38:54,380
primed for simple life.
770
00:38:54,380 --> 00:38:56,280
So, if you have planet 9,
771
00:38:56,290 --> 00:38:58,120
and it's got icy moons,
and these icy moons
772
00:38:58,120 --> 00:39:00,290
are on the right
kinds of orbits,
773
00:39:00,290 --> 00:39:03,360
the heat could be coming
from within, not without.
774
00:39:03,360 --> 00:39:06,190
And so the Sun basically
doesn't matter.
775
00:39:06,200 --> 00:39:09,700
You could have liquid water
below the surface
776
00:39:09,700 --> 00:39:11,930
that's heated from
the internal geology.
777
00:39:11,940 --> 00:39:13,740
You could have geysers of water
778
00:39:13,740 --> 00:39:15,200
like what we see
coming off of moons
779
00:39:15,210 --> 00:39:16,810
around Saturn and Jupiter.
780
00:39:16,810 --> 00:39:19,170
You could have that all the
way out there at planet 9.
781
00:39:22,850 --> 00:39:27,980
Imagine planet 9
with a system of giant moons.
782
00:39:27,980 --> 00:39:30,790
The closest moon
is heated to melting point
783
00:39:30,790 --> 00:39:34,020
by planet 9's immense gravity.
784
00:39:34,020 --> 00:39:35,560
There's no life here.
785
00:39:35,560 --> 00:39:38,490
Any water boiled away
millions of years ago,
786
00:39:38,500 --> 00:39:41,430
creating a hot,
arid ball of rock.
787
00:39:44,430 --> 00:39:47,100
Farther out lies
a second giant moon.
788
00:39:47,100 --> 00:39:51,540
This new world is encased
in bright, white water ice.
789
00:39:54,180 --> 00:39:56,240
But the crust hides a secret...
790
00:39:56,250 --> 00:39:59,250
a vast ocean
of warm liquid water
791
00:39:59,250 --> 00:40:02,480
heated by volcanic vents
on the ocean floor.
792
00:40:04,720 --> 00:40:08,120
This hidden world is rich
with organic chemistry.
793
00:40:08,120 --> 00:40:13,030
And it could even support
a weird, alien zoo
794
00:40:13,030 --> 00:40:16,100
of pale aquatic creatures.
795
00:40:16,100 --> 00:40:18,400
We associate life with the Sun.
796
00:40:18,400 --> 00:40:20,970
That's how we think of life
originating on the Earth.
797
00:40:20,970 --> 00:40:22,600
But we know
you don't need the Sun.
798
00:40:22,610 --> 00:40:25,170
We have tube worms
at the bottom of the ocean
799
00:40:25,180 --> 00:40:27,180
which live off
of hydrothermal vents.
800
00:40:27,180 --> 00:40:29,240
They get all the chemicals
and the heat they need
801
00:40:29,250 --> 00:40:31,550
from, basically,
the interior of the Earth.
802
00:40:31,550 --> 00:40:33,820
This is not out of the question.
You know, decades ago,
803
00:40:33,820 --> 00:40:35,820
you'd have been laughed
out of a lecture hall
804
00:40:35,820 --> 00:40:37,820
if you'd have said
something like that.
805
00:40:37,820 --> 00:40:39,890
But we have learned
so much about life
806
00:40:39,890 --> 00:40:41,220
in extreme environments
since then
807
00:40:41,220 --> 00:40:43,520
that this is now
in the realm of possibility,
808
00:40:43,530 --> 00:40:45,090
talking about life on a planet
809
00:40:45,100 --> 00:40:47,100
beyond Pluto
in our own solar system.
810
00:40:47,100 --> 00:40:48,700
Wherever there's energy,
811
00:40:48,700 --> 00:40:50,700
wherever there's heat,
there can be life,
812
00:40:50,700 --> 00:40:54,070
even all the way
out by planet 9.
813
00:40:54,070 --> 00:40:55,570
There is good news.
814
00:40:55,570 --> 00:40:58,570
If planet 9 does have
an active watery moon,
815
00:40:58,580 --> 00:41:01,210
we should be able to see it
with our telescopes.
816
00:41:03,550 --> 00:41:05,580
The active moons
of Jupiter and Saturn
817
00:41:05,580 --> 00:41:07,880
are the brightest
in the night sky,
818
00:41:07,880 --> 00:41:11,620
thanks to warm water gushing
out from cracks in the surface
819
00:41:11,620 --> 00:41:16,960
and freezing in bright
white layers of fresh ice.
820
00:41:16,960 --> 00:41:19,890
If planet 9's moons
have liquid oceans,
821
00:41:19,900 --> 00:41:23,100
their surfaces should be
just as bright.
822
00:41:30,570 --> 00:41:34,340
The race is on to image
planet 9 and its moons.
823
00:41:34,340 --> 00:41:37,850
But what we'll see
when those pictures come back
824
00:41:37,850 --> 00:41:39,380
is anybody's guess.
825
00:41:39,380 --> 00:41:41,480
I have to admit, there's
some wonderful tension
826
00:41:41,480 --> 00:41:44,290
that I feel right now when it
comes to finding planet 9.
827
00:41:44,290 --> 00:41:45,850
We have giant telescopes
828
00:41:45,860 --> 00:41:48,120
that are scanning the sky
looking for it.
829
00:41:48,120 --> 00:41:51,560
So, any day now, I'm waiting
with baited breath.
830
00:41:51,560 --> 00:41:52,790
My daughter believes
831
00:41:52,800 --> 00:41:56,100
that planet 9 is pink
with purple dots.
832
00:41:56,100 --> 00:41:58,900
Um, she might be right.
833
00:42:03,340 --> 00:42:04,740
One thing's for sure.
834
00:42:04,740 --> 00:42:07,980
If and when we do find planet 9,
835
00:42:07,980 --> 00:42:12,150
we'll never look at our solar
system the same way again.
836
00:42:12,150 --> 00:42:13,850
This is tremendously exciting,
837
00:42:13,850 --> 00:42:16,050
because, if it's there,
it's already telling us
838
00:42:16,050 --> 00:42:20,690
that there's more to know
about our solar system,
839
00:42:20,690 --> 00:42:23,690
that there are more secrets
literally under the Sun
840
00:42:23,690 --> 00:42:26,160
than we have dreamed of
in our philosophy.
65155
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