1
00:00:09,847 --> 00:00:13,681
<i>We've all grown up wondering</i>
<i>if we're alone in the universe,</i>

2
00:00:13,847 --> 00:00:18,079
<i>or if, one day, we might come</i>
<i>face to face with an alien.</i>

3
00:00:24,087 --> 00:00:29,115
<i>This is the story of our search</i>
<i>for extra terrestrials.</i>

4
00:00:29,287 --> 00:00:31,437
<i>Does ET really exist?</i>

5
00:00:31,607 --> 00:00:34,167
<i>We're going on a journey to find out.</i>

6
00:00:37,687 --> 00:00:41,396
<i>We'll visit alien planets</i>
<i>in search of life.</i>

7
00:00:46,807 --> 00:00:50,641
<i>We'll dive into the oceans</i>
<i>of distant moons.</i>

8
00:00:51,807 --> 00:00:55,959
<i>Here on Earth,</i>
<i>we'll scan the universe for alien life.</i>

9
00:00:58,447 --> 00:01:03,043
<i>And seek out the answer</i>
<i>to one of the greatest questions</i> -

10
00:01:03,207 --> 00:01:05,960
<i>is there life on other worlds?</i>

11
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<i>Or, in all the vastness of space,</i>

12
00:01:11,487 --> 00:01:15,560
<i>could it really be that we are</i>
<i>completely and utterly alone?</i>

13
00:01:40,527 --> 00:01:43,519
<i>We already know</i>
<i>that we are not alone.</i>

14
00:01:50,807 --> 00:01:55,756
<i>We share our planet with at least</i>
<i>ten million other species.</i>

15
00:02:01,887 --> 00:02:05,516
<i>This is life on Earth.</i>

16
00:02:10,967 --> 00:02:13,003
<i>From the ordinary...</i>

17
00:02:13,167 --> 00:02:15,158
<i>to the utterly bizarre.</i>

18
00:02:21,447 --> 00:02:26,726
<i>So, what about other planets?</i>
<i>Could they have produced life, too?</i>

19
00:02:26,887 --> 00:02:30,402
<i>There's one creature on Earth</i>
<i>that would like to know</i> -

20
00:02:32,127 --> 00:02:33,799
<i>us!</i>

21
00:02:38,607 --> 00:02:42,316
<i>If intelligent life could evolve</i>
<i>here on Earth,</i>

22
00:02:42,487 --> 00:02:44,478
<i>then why not elsewhere?</i>

23
00:02:44,647 --> 00:02:48,481
<i>We're the first generation</i>
<i>that might actually find out.</i>

24
00:02:52,407 --> 00:02:57,197
<i>Scientists have begun to discover</i>
<i>new worlds out there in space.</i>

25
00:03:00,127 --> 00:03:04,086
<i>Places where one day</i>
<i>we might encounter alien life.</i>

26
00:03:06,127 --> 00:03:08,641
<i>So, how long before we find the answer</i>

27
00:03:08,807 --> 00:03:11,685
<i>to the question</i>
<i>we really want answered?</i>

28
00:03:11,847 --> 00:03:14,315
<i>Is there anybody out there?</i>

29
00:03:16,127 --> 00:03:18,118
<i>Look at the stars.</i>

30
00:03:22,527 --> 00:03:28,124
<i>Each of them is a sun like ours,</i>
<i>and our sun has planet Earth.</i>

31
00:03:29,687 --> 00:03:34,715
<i>Could this really be the only planet</i>
<i>anywhere that's full of life?</i>

32
00:03:38,167 --> 00:03:41,603
<i>To find out, we must</i>
<i>leave our own world behind.</i>

33
00:03:43,447 --> 00:03:45,722
<i>Let's travel further.</i>

34
00:03:47,487 --> 00:03:51,116
<i>Beyond our sun and out into space.</i>

35
00:03:59,487 --> 00:04:02,604
<i>There's Mars, cold and inhospitable.</i>

36
00:04:06,887 --> 00:04:12,041
<i>Next is Jupiter,</i>
<i>a vast and lifeless ball of gas.</i>

37
00:04:14,087 --> 00:04:17,045
<i>Then another gas giant</i> - <i>Saturn.</i>

38
00:04:22,567 --> 00:04:25,320
<i>Then Uranus, Neptune and on.</i>

39
00:04:26,727 --> 00:04:29,366
<i>All the other planets</i>
<i>of our solar system</i>

40
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<i>are barren worlds, devoid of life.</i>

41
00:04:31,967 --> 00:04:35,084
<i>But beyond our solar system</i>
<i>are the stars</i>

42
00:04:35,247 --> 00:04:38,717
<i>and, remember, each of these</i>
<i>is another sun.</i>

43
00:04:38,887 --> 00:04:42,516
<i>400,000 million of them</i>
<i>in a vast, swirling cloud.</i>

44
00:04:44,047 --> 00:04:47,119
<i>The Milky Way</i> - <i>our galaxy.</i>

45
00:04:47,287 --> 00:04:51,724
<i>And when you leave</i>
<i>our galaxy behind,</i>

46
00:04:51,887 --> 00:04:56,517
<i>you begin to realise</i>
<i>just how vast the universe is.</i>

47
00:04:56,687 --> 00:05:00,680
<i>Because each of these</i>
<i>is a galaxy just like ours.</i>

48
00:05:00,847 --> 00:05:04,726
<i>And these are clouds of galaxies.</i>

49
00:05:04,887 --> 00:05:10,086
<i>Is it really possible that the</i>
<i>only planet with intelligent life</i>

50
00:05:10,247 --> 00:05:12,363
<i>is this one?</i>

51
00:05:19,887 --> 00:05:21,923
<i>It's all a question of numbers.</i>

52
00:05:22,087 --> 00:05:24,521
<i>If there are enough stars out there,</i>

53
00:05:24,687 --> 00:05:29,715
<i>the chances that alien life exists</i>
<i>could be very good indeed.</i>

54
00:05:37,287 --> 00:05:41,519
<i>It's hard to comprehend</i>
<i>just how many stars there are.</i>

55
00:05:42,887 --> 00:05:45,765
<i>Each point of light</i>
<i>is a whole galaxy,</i>

56
00:05:45,927 --> 00:05:49,966
<i>billions of stars</i>
<i>in every pinprick of light.</i>

57
00:05:52,287 --> 00:05:54,926
<i>Look at a handful of sand.</i>

58
00:05:55,087 --> 00:05:59,080
<i>How many grains?</i>
<i>Thousands? Hundreds of thousands?</i>

59
00:05:59,247 --> 00:06:01,886
<i>How many grains on a whole beach?</i>

60
00:06:04,007 --> 00:06:07,124
<i>The numbers</i>
<i>are too big to think about.</i>

61
00:06:08,127 --> 00:06:09,879
<i>Well, think about this.</i>

62
00:06:10,047 --> 00:06:14,438
<i>For every grain of sand</i>
<i>on our entire planet,</i>

63
00:06:14,607 --> 00:06:17,804
<i>there are a million stars</i>
<i>out there in space.</i>

64
00:06:18,807 --> 00:06:23,835
<i>A million stars just like our sun</i>
<i>for every grain of sand.</i>

65
00:06:24,007 --> 00:06:27,079
<i>Where there are stars,</i>
<i>there may be planets.</i>

66
00:06:27,247 --> 00:06:30,842
<i>And where there are planets,</i>
<i>there may be life.</i>

67
00:06:32,127 --> 00:06:36,917
<i>It's happened here.</i>
<i>So, where is everybody else?</i>

68
00:06:37,087 --> 00:06:42,366
If there are intelligent beings
up there trying to contact us,

69
00:06:42,527 --> 00:06:47,840
their messages will be picked up here
probably before anywhere else.

70
00:06:48,007 --> 00:06:52,842
But to hear the voices of
the planets, you need a big ear.

71
00:06:53,007 --> 00:06:55,396
This is the biggest ear on Earth.

72
00:07:01,047 --> 00:07:05,279
<i>For the last 35 years, scientists</i>
<i>have been working on a project</i>

73
00:07:05,447 --> 00:07:08,439
<i>to settle the question</i>
<i>of whether we're alone.</i>

74
00:07:09,887 --> 00:07:14,119
<i>Their mission</i> - <i>to scan</i>
<i>every star in the sky</i>

75
00:07:14,287 --> 00:07:16,721
<i>for signs of alien life.</i>

76
00:07:18,567 --> 00:07:24,005
<i>It's called SETI</i> - <i>the Search for</i>
<i>Extra Terrestrial Intelligence.</i>

77
00:07:24,167 --> 00:07:26,476
<i>And they're still doing it today.</i>

78
00:07:37,527 --> 00:07:39,085
CQ, 20 metres,

79
00:07:39,247 --> 00:07:43,445
this is N6 Uncle Donald Kilowatt
calling and standing by.

80
00:07:43,607 --> 00:07:46,997
<i>Seth Shostack</i>
<i>is a SETI astronomer.</i>

81
00:07:47,167 --> 00:07:51,001
<i>His job is to listen out</i>
<i>for ET on the radio.</i>

82
00:07:52,767 --> 00:07:58,763
Radio cuts right through the gas and dust
that hangs between the stars.

83
00:07:58,927 --> 00:08:03,796
Radio is an easy communication
medium for us and them to use,

84
00:08:03,967 --> 00:08:07,482
so we figure they're probably using
a lot of radio.

85
00:08:18,287 --> 00:08:23,077
There is so much cosmic
real estate, so many stars,

86
00:08:23,247 --> 00:08:28,037
that it's hard to believe that this
is only bit in the entire cosmos

87
00:08:28,207 --> 00:08:32,280
that's populated by beings
able to develop radio technology.

88
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<i>In the first decade of searching,</i>
<i>SETI had nothing to show.</i>

89
00:08:44,367 --> 00:08:47,245
<i>Then, in 1977, that changed.</i>

90
00:08:47,407 --> 00:08:52,481
<i>A SETI computer detected</i>
<i>exactly what they were looking for</i> -

91
00:08:52,647 --> 00:08:56,686
<i>a powerful radio beam</i>
<i>from another star.</i>

92
00:09:02,247 --> 00:09:05,364
<i>Could it have been a signal</i>
<i>from an alien race?</i>

93
00:09:11,087 --> 00:09:12,964
<i>We may never know.</i>

94
00:09:13,127 --> 00:09:16,403
<i>By the time they could train</i>
<i>more instruments on it,</i>

95
00:09:16,567 --> 00:09:18,205
<i>the signal had vanished.</i>

96
00:09:18,367 --> 00:09:20,278
<i>It remains unexplained.</i>

97
00:09:29,767 --> 00:09:35,239
<i>One sniff of success in 35 years</i>
<i>of searching might put you off,</i>

98
00:09:35,407 --> 00:09:38,558
<i>but Seth Shostack is undaunted.</i>

99
00:09:38,727 --> 00:09:43,562
If we do this for 100 years
and don't find a signal, I'd be nonplussed.

100
00:09:43,727 --> 00:09:46,844
I'd also be dead,
but it would surprise me.

101
00:09:47,007 --> 00:09:51,398
I think that this experiment
is almost guaranteed to succeed.

102
00:09:51,567 --> 00:09:53,762
<i>But despite Seth's optimism,</i>

103
00:09:53,927 --> 00:09:56,919
<i>finding extra terrestrials</i>
<i>could take some time.</i>

104
00:09:57,087 --> 00:09:59,123
<i>There are too many stars to search.</i>

105
00:10:02,807 --> 00:10:07,756
<i>The problem is, our galaxy</i>
<i>is truly immense.</i>

106
00:10:07,967 --> 00:10:11,562
<i>This is us, just here.</i>
<i>That star is the sun.</i>

107
00:10:11,727 --> 00:10:16,198
<i>And this is the area we've</i>
<i>searched so far for alien signals.</i>

108
00:10:17,327 --> 00:10:22,117
<i>Not bad, until you see</i>
<i>how many stars there are to search.</i>

109
00:10:31,727 --> 00:10:37,563
<i>Finding extra terrestrial beings</i>
<i>might seem like a daunting task,</i>

110
00:10:37,727 --> 00:10:39,206
<i>but it may not be in vain.</i>

111
00:10:39,367 --> 00:10:42,484
<i>We've started to find places</i>
<i>where they could live.</i>

112
00:10:47,607 --> 00:10:49,484
<i>Hawaii.</i>

113
00:10:53,927 --> 00:10:56,566
<i>Far above the clouds of Big Island</i>

114
00:10:56,727 --> 00:10:59,685
<i>sits the largest telescope</i>
<i>in the world.</i>

115
00:11:05,407 --> 00:11:07,602
<i>Scientists come here to search</i>

116
00:11:07,767 --> 00:11:11,237
<i>for what they recently believed</i>
<i>was impossible.</i>

117
00:11:11,407 --> 00:11:15,480
<i>Evidence of planets</i>
<i>circling around distant stars.</i>

118
00:11:15,647 --> 00:11:18,207
What object next, guys?

119
00:11:18,367 --> 00:11:22,076
We'll continue stepping down 93 31.

120
00:11:22,247 --> 00:11:27,082
All right, lining up on slit.
We are ready for exposure.

121
00:11:27,247 --> 00:11:29,397
And...shooting.

122
00:11:31,487 --> 00:11:34,797
<i>At first glance,</i>
<i>their task seems hopeless.</i>

123
00:11:34,967 --> 00:11:39,882
<i>Finding a planet around another</i>
<i>star is like finding a grain of sand</i>

124
00:11:40,047 --> 00:11:41,639
<i>on the moon.</i>

125
00:11:43,887 --> 00:11:46,276
<i>But there's a trick to it.</i>

126
00:11:46,447 --> 00:11:49,883
<i>Don't even look for the planet.</i>
<i>Look at the star.</i>

127
00:11:52,567 --> 00:11:55,843
<i>Geoff Marcy is one</i>
<i>of a new breed of scientist</i> -

128
00:11:56,007 --> 00:11:58,043
<i>a planet hunter.</i>

129
00:11:58,207 --> 00:12:00,641
If there's a planet
going round a star,

130
00:12:00,807 --> 00:12:04,402
we'll never see the planet
lost in the glare of the star.

131
00:12:04,567 --> 00:12:08,446
What we do,
is we watch the star itself.

132
00:12:08,607 --> 00:12:10,882
We watch if it wobbles in space.

133
00:12:14,927 --> 00:12:18,044
It's very much like
a hammer thrower.

134
00:12:18,207 --> 00:12:22,485
As the hammer thrower wheels
this huge mass around his head,

135
00:12:22,647 --> 00:12:27,118
the hammer thrower wobbles around,
pulled by the hammer.

136
00:12:27,287 --> 00:12:30,006
Even if you couldn't
see the hammer,

137
00:12:30,167 --> 00:12:34,399
you'd be able to tell that he had
a large mass at the end of a rope.

138
00:12:34,567 --> 00:12:39,357
So, you can tell a lot about
the planets going around a star

139
00:12:39,527 --> 00:12:42,087
by just watching the star itself.

140
00:12:47,967 --> 00:12:50,197
<i>The idea</i>
<i>that you can detect a planet</i>

141
00:12:50,367 --> 00:12:55,441
<i>by the minuscule wobble it creates</i>
<i>in a star is frankly astonishing.</i>

142
00:12:56,607 --> 00:13:00,646
<i>Small wonder that success</i>
<i>was a long time coming.</i>

143
00:13:05,367 --> 00:13:09,360
We started our planet search
way back in 1986.

144
00:13:11,687 --> 00:13:15,236
We went for nine years
without finding anything.

145
00:13:16,567 --> 00:13:20,276
And then in 1995,
we started finding some.

146
00:13:20,447 --> 00:13:25,077
And now we're finding planets
so fast, we can barely keep up.

147
00:13:26,087 --> 00:13:30,160
Every month,
we find another two or three.

148
00:13:30,327 --> 00:13:34,286
It's like we have to stuff
the planets in our mouths

149
00:13:34,447 --> 00:13:39,521
to pretend that we are keeping up,
when, in fact, we're not.

150
00:13:43,487 --> 00:13:45,637
There's almost no question

151
00:13:45,807 --> 00:13:50,437
that there are literally
hundreds of billions of planets

152
00:13:50,607 --> 00:13:54,964
just in our own galaxy,
many of which could harbour life.

153
00:14:00,047 --> 00:14:04,086
<i>One by one, astronomers</i>
<i>were finding alien worlds.</i>

154
00:14:10,527 --> 00:14:14,759
<i>But their hopes of finding</i>
<i>alien beings soon faded.</i>

155
00:14:14,927 --> 00:14:19,717
<i>Every world they've discovered</i>
<i>appears lifeless.</i>

156
00:14:19,887 --> 00:14:25,245
<i>These are gas giants, with no</i>
<i>solid surface for life to live on,</i>

157
00:14:25,407 --> 00:14:30,435
<i>and most are so close to their stars</i>
<i>that the heat would be lethal.</i>

158
00:14:40,447 --> 00:14:43,996
<i>To find worlds</i>
<i>where aliens could live,</i>

159
00:14:44,167 --> 00:14:46,761
<i>they'll need a whole new approach.</i>

160
00:14:59,087 --> 00:15:01,317
<i>And this could be it.</i>

161
00:15:03,487 --> 00:15:08,561
<i>A fleet of orbiting telescopes</i>
<i>flying in laser-guided formation.</i>

162
00:15:08,727 --> 00:15:13,437
<i>Each is many times more powerful</i>
<i>than the Hubble space telescope.</i>

163
00:15:21,807 --> 00:15:24,844
<i>When they are launched in 2025,</i>

164
00:15:26,007 --> 00:15:30,683
<i>the telescopes won't be looking</i>
<i>for the subtle wobble of a star.</i>

165
00:15:30,847 --> 00:15:34,203
<i>They'll look straight</i>
<i>at the planet itself.</i>

166
00:15:38,087 --> 00:15:43,115
<i>They'll analyse its atmosphere,</i>
<i>perhaps even tell us if there's life.</i>

167
00:15:43,287 --> 00:15:47,599
<i>One day, we'll be able</i>
<i>to look out into space</i>

168
00:15:47,767 --> 00:15:50,804
<i>and see other worlds like ours.</i>

169
00:15:54,687 --> 00:15:57,645
I think,
for almost any human being,

170
00:15:57,807 --> 00:16:02,323
the picture of another Earth
orbiting another star

171
00:16:02,487 --> 00:16:05,047
would be like looking
in the mirror,

172
00:16:05,207 --> 00:16:07,675
but not one you see in the morning.

173
00:16:07,847 --> 00:16:11,317
This would be a mirror
of our whole solar system

174
00:16:11,487 --> 00:16:13,364
and our beloved planet.

175
00:16:13,527 --> 00:16:15,995
Seeing it mirrored in another star

176
00:16:16,167 --> 00:16:19,477
would be one of the most exciting
days in any life.

177
00:16:22,967 --> 00:16:25,435
<i>It is an astonishing prospect.</i>

178
00:16:25,607 --> 00:16:28,405
<i>But if we're looking</i>
<i>for alien life,</i>

179
00:16:28,567 --> 00:16:33,516
<i>finding another planet so much</i>
<i>like our own may not be necessary.</i>

180
00:16:35,687 --> 00:16:39,043
<i>Our planet</i>
<i>has everything life needs</i> -

181
00:16:39,207 --> 00:16:42,244
<i>air, water, even sunlight,</i>
<i>if you're lucky.</i>

182
00:16:42,407 --> 00:16:44,875
<i>Conditions here are just right</i> - <i>for us.</i>

183
00:16:45,047 --> 00:16:49,120
<i>But who's to say alien life</i>
<i>would thrive on the same things?</i>

184
00:16:49,287 --> 00:16:51,437
<i>What if it doesn't need sun or air?</i>

185
00:16:58,167 --> 00:17:00,397
<i>Three kilometres down in the ocean</i>

186
00:17:00,567 --> 00:17:03,559
<i>lies one of the harshest</i>
<i>environments we know.</i>

187
00:17:04,567 --> 00:17:07,035
<i>This is a volcanic vent.</i>

188
00:17:11,327 --> 00:17:14,558
<i>The temperature here</i>
<i>is over 100 degrees.</i>

189
00:17:14,727 --> 00:17:18,800
<i>There's total darkness,</i>
<i>pressures to crush a human to a pulp.</i>

190
00:17:20,447 --> 00:17:24,076
<i>These creatures</i>
<i>should literally be cooked.</i>

191
00:17:32,007 --> 00:17:34,202
<i>But here they are.</i>

192
00:17:41,207 --> 00:17:45,519
<i>If living things can thrive here,</i>
<i>then where else?</i>

193
00:17:54,127 --> 00:17:57,722
<i>Scientists' quests</i>
<i>for new lifeforms have led them</i>

194
00:17:57,887 --> 00:18:00,355
<i>to the most hostile environments.</i>

195
00:18:03,967 --> 00:18:07,926
<i>This cave is the relic</i>
<i>of a vast volcanic eruption</i>

196
00:18:08,087 --> 00:18:11,079
<i>that occurred</i>
<i>millions of years ago.</i>

197
00:18:11,247 --> 00:18:15,957
<i>It's a lava tube</i> - <i>a gully</i>
<i>left behind by a river of molten rock,</i>

198
00:18:16,127 --> 00:18:17,879
<i>sterilised by the heat.</i>

199
00:18:18,047 --> 00:18:23,201
<i>When the rock solidified, the tube</i>
<i>was sealed off from the world.</i>

200
00:18:25,287 --> 00:18:30,042
<i>There's nothing here to live on.</i>
<i>No sunlight. Nothing but rock.</i>

201
00:18:31,447 --> 00:18:33,915
<i>This truly is another world.</i>

202
00:18:36,527 --> 00:18:39,644
<i>Penny Boston is a specialist</i>
<i>in finding life</i>

203
00:18:39,807 --> 00:18:42,321
<i>where it shouldn't exist.</i>

204
00:18:42,487 --> 00:18:46,605
The important thing about
looking for life on other planets

205
00:18:46,767 --> 00:18:53,081
is to keep your imagination
as broad as you possibly can.

206
00:18:53,247 --> 00:18:55,636
Try not to go with pre-conceptions,

207
00:18:55,807 --> 00:18:58,640
because you never know
what you'll find.

208
00:18:58,807 --> 00:19:01,162
We can only go
with our best guesses,

209
00:19:01,327 --> 00:19:03,636
depending on what we find on Earth.

210
00:19:08,447 --> 00:19:11,962
<i>If Penny's team finds life here,</i>

211
00:19:12,127 --> 00:19:16,678
<i>it is surviving conditions</i>
<i>we used to claim were impossible.</i>

212
00:19:16,847 --> 00:19:20,078
<i>If life can survive</i>
<i>impossible conditions on Earth,</i>

213
00:19:20,247 --> 00:19:23,523
<i>why not on other worlds?</i>

214
00:19:27,247 --> 00:19:31,445
<i>And this is the first place</i>
<i>to look</i> - <i>Mars.</i>

215
00:19:33,007 --> 00:19:37,683
<i>Like the caves on Earth,</i>
<i>there's little here for life</i> -

216
00:19:37,847 --> 00:19:42,796
<i>not much water or air,</i>
<i>nothing but rock to live on.</i>

217
00:19:54,167 --> 00:19:56,203
<i>But perhaps the rocks of Mars</i>

218
00:19:56,367 --> 00:19:59,518
<i>will hide similar wonders</i>
<i>to those of Earth.</i>

219
00:20:00,607 --> 00:20:03,075
<i>The miracle of life.</i>

220
00:20:15,207 --> 00:20:19,120
That is cool. Look how much
it narrows down there.

221
00:20:19,287 --> 00:20:21,323
Could that be a nematode?

222
00:20:30,527 --> 00:20:33,439
<i>Penny's discoveries in these caves</i>

223
00:20:33,607 --> 00:20:37,441
<i>make the odds of finding life</i>
<i>on Mars far higher.</i>

224
00:20:37,607 --> 00:20:41,520
<i>And life on Mars could mean life</i>
<i>on other planets as well.</i>

225
00:20:43,007 --> 00:20:44,645
If we find life on Mars,

226
00:20:44,807 --> 00:20:48,595
I think that our chances
of finding life beyond Mars,

227
00:20:48,767 --> 00:20:52,555
and other places in the universe,
go up enormously.

228
00:20:52,727 --> 00:20:57,403
Two planets in just one solar system
have life on them.

229
00:20:57,567 --> 00:21:02,277
That means that life is a pretty
common phenomenon in the universe.

230
00:21:05,247 --> 00:21:07,761
<i>So, where to search after Mars?</i>

231
00:21:15,767 --> 00:21:19,555
<i>This is probably the strongest</i>
<i>candidate for alien life</i>

232
00:21:19,727 --> 00:21:21,319
<i>in our solar system.</i>

233
00:21:21,487 --> 00:21:25,719
<i>It's one of Jupiter's 16 moons</i> -
<i>Europa.</i>

234
00:21:25,887 --> 00:21:28,321
<i>It appears tiny next to Jupiter,</i>

235
00:21:28,487 --> 00:21:31,126
<i>but Europa is almost as big as Earth.</i>

236
00:21:32,607 --> 00:21:34,837
<i>This is an ice world,</i>

237
00:21:35,007 --> 00:21:39,364
<i>its surface frozen</i>
<i>to a crippling 150 below zero.</i>

238
00:21:40,927 --> 00:21:43,521
<i>Life here looks impossible.</i>

239
00:21:47,967 --> 00:21:52,085
<i>But there is a plan</i>
<i>to drop a probe onto Europa.</i>

240
00:21:52,247 --> 00:21:56,206
<i>And if they do, scientists</i>
<i>expect to find something amazing.</i>

241
00:22:11,207 --> 00:22:14,677
<i>Beneath Europa's ice,</i>
<i>there is an ocean.</i>

242
00:22:24,567 --> 00:22:26,603
<i>What will we find there?</i>

243
00:22:26,767 --> 00:22:30,396
<i>Scientists are almost certain</i>
<i>the probe will find</i>

244
00:22:30,567 --> 00:22:33,525
<i>deep sea vents</i>
<i>similar to those on Earth.</i>

245
00:22:43,087 --> 00:22:46,159
<i>Could the vents on Europa</i>
<i>have life?</i>

246
00:22:50,327 --> 00:22:55,117
<i>If so, it seems certain</i>
<i>we'll find life across the universe.</i>

247
00:22:58,687 --> 00:23:00,803
I think there's frankly no doubt

248
00:23:00,967 --> 00:23:05,722
that there must be life elsewhere
in our galaxy, at least primitive life.

249
00:23:09,607 --> 00:23:14,522
The bio-chemists tell us
that if a planet has liquid water,

250
00:23:14,687 --> 00:23:17,759
you will get replicating molecules.

251
00:23:18,927 --> 00:23:23,717
The most successful would compete
with other replicating molecules,

252
00:23:23,887 --> 00:23:27,675
and there, voilą, you have life,
ever more complex.

253
00:23:30,287 --> 00:23:33,723
The question for which
we don't have an answer

254
00:23:33,887 --> 00:23:38,005
is whether our Milky Way galaxy
harbours any intelligent life.

255
00:23:39,807 --> 00:23:42,162
And that is
the $64 million question.

256
00:23:43,327 --> 00:23:44,965
<i>So, are we alone?</i>

257
00:23:45,127 --> 00:23:48,164
<i>The only intelligent creatures</i>

258
00:23:48,327 --> 00:23:51,637
<i>in a universe teeming</i>
<i>with simpler lifeforms?</i>

259
00:23:54,807 --> 00:23:56,798
<i>It's hard to believe.</i>

260
00:24:00,767 --> 00:24:03,759
<i>With so much life,</i>
<i>some of those creatures</i>

261
00:24:03,927 --> 00:24:07,761
<i>should surely have evolved</i>
<i>into intelligent beings.</i>

262
00:24:07,927 --> 00:24:10,999
<i>Perhaps beings a little like us.</i>

263
00:24:13,007 --> 00:24:15,885
<i>That just begs more questions.</i>

264
00:24:16,047 --> 00:24:19,881
<i>Where are they?</i>
<i>Why haven't THEY contacted US?</i>

265
00:24:20,047 --> 00:24:25,075
<i>After all, we've been making</i>
<i>noise for more than 50 years.</i>

266
00:24:27,647 --> 00:24:30,798
(RADIO PLAYS ''MOONLIGHT
SERENADE'' BY GLEN MILLER)

267
00:24:36,047 --> 00:24:40,598
<i>Here's the puzzle. Our radio</i>
<i>broadcasts don't just reach us.</i>

268
00:24:40,767 --> 00:24:43,042
<i>They also beam out into space.</i>

269
00:24:45,087 --> 00:24:47,476
(GEORGE W BUSH)
I do solemnly swear

270
00:24:47,647 --> 00:24:52,118
that I will faithfully execute
the office of President of the USA.

271
00:24:53,567 --> 00:24:57,401
<i>Planet Earth's history is being</i>
<i>broadcast to the universe.</i>

272
00:25:01,567 --> 00:25:04,684
<i>So, if extra terrestrials exist,</i>

273
00:25:04,847 --> 00:25:08,681
<i>they should already know</i>
<i>that we are here.</i>

274
00:25:11,367 --> 00:25:15,838
(BILL CLINTON)
I do solemnly swear...

275
00:25:16,407 --> 00:25:19,558
(''ALL RIGHT NOW'' BY FREE
PLAYS)

276
00:25:19,727 --> 00:25:24,005
<i>But even radio takes years</i>
<i>to reach the stars.</i>

277
00:25:24,167 --> 00:25:28,604
(RONALD REAGAN)
I do solemnly swear...

278
00:25:28,767 --> 00:25:31,042
# I'm the urban spaceman, baby... #

279
00:25:31,207 --> 00:25:33,721
(JIMMY CARTER)
I do solemnly swear...

280
00:25:33,887 --> 00:25:36,355
# And it's hi ho, silver lining... #

281
00:25:36,527 --> 00:25:39,519
(RICHARD NIXON)
I do solemnly swear...

282
00:25:39,687 --> 00:25:44,477
<i>Our radio broadcasts have</i>
<i>beamed into space for five decades.</i>

283
00:25:44,647 --> 00:25:46,558
<i>But in all that time,</i>

284
00:25:46,727 --> 00:25:51,482
<i>they've only reached a handful</i>
<i>of the closest stars.</i>

285
00:25:51,647 --> 00:25:56,357
<i>To most of space, our planet</i>
<i>appears completely silent.</i>

286
00:25:56,527 --> 00:25:59,599
(DWIGHT EISENHOWER)
I do solemnly swear...

287
00:25:59,767 --> 00:26:04,238
# Life could be a dream, sweetheart
Hello, hello again, she-boom... #

288
00:26:17,047 --> 00:26:21,837
There's this bubble of TV,
if you will, moving out into space.

289
00:26:22,007 --> 00:26:24,840
The earliest shows
have gone 50 light years.

290
00:26:25,007 --> 00:26:27,965
There's only a few hundred stars
that close.

291
00:26:28,127 --> 00:26:30,243
The aliens don't know we're here.

292
00:26:30,407 --> 00:26:32,841
That's why we haven't
heard from them.

293
00:26:33,007 --> 00:26:35,680
<i>Some day,</i>
<i>as that radio bubble expands,</i>

294
00:26:35,847 --> 00:26:42,286
<i>someone out there might</i>
<i>learn that we're here, but when?</i>

295
00:26:46,007 --> 00:26:48,202
<i>And what happens next?</i>

296
00:26:50,807 --> 00:26:55,722
<i>It's the sheer size of the galaxy.</i>
<i>That's the problem.</i>

297
00:26:55,887 --> 00:26:57,843
<i>If extra terrestrials exist,</i>

298
00:26:58,007 --> 00:27:01,363
<i>they could live</i>
<i>on the other side from Earth.</i>

299
00:27:01,527 --> 00:27:04,246
<i>It would take our radio and TV broadcasts</i>

300
00:27:04,407 --> 00:27:06,637
<i>100,000 years to reach them.</i>

301
00:27:06,807 --> 00:27:10,595
<i>We've only been sending out signals</i>
<i>for around 50I</i>

302
00:27:14,767 --> 00:27:16,962
<i>It just depends where ET lives.</i>

303
00:27:17,127 --> 00:27:21,006
<i>Our signals have only reached</i>
<i>a handful of stars,</i>

304
00:27:21,167 --> 00:27:22,964
<i>but that may be enough.</i>

305
00:27:26,167 --> 00:27:29,955
<i>This star is just receiving</i>
<i>our first radio broadcast.</i>

306
00:27:30,127 --> 00:27:32,846
<i>So, if ET lives</i>
<i>on a planet round here,</i>

307
00:27:33,007 --> 00:27:36,238
<i>they might have just found out</i>
<i>that we exist.</i>

308
00:27:36,407 --> 00:27:38,238
<i>If they choose to answer,</i>

309
00:27:38,407 --> 00:27:42,366
<i>the message will take another</i>
<i>50 years to come back to us.</i>

310
00:27:43,687 --> 00:27:45,723
<i>So we might be waiting a while</i>

311
00:27:45,887 --> 00:27:48,447
<i>before we discover</i>
<i>we are not alone.</i>

312
00:27:48,607 --> 00:27:51,883
<i>Unless, of course,</i>
<i>they had one of these.</i>

313
00:28:06,567 --> 00:28:09,639
<i>Intelligent beings</i>
<i>from another world.</i>

314
00:28:09,807 --> 00:28:11,525
Gee whiz!

315
00:28:12,847 --> 00:28:15,156
<i>What would they be like?</i>

316
00:28:15,327 --> 00:28:19,957
<i>Almost certainly like nothing</i>
<i>we've ever imagined.</i>

317
00:28:24,967 --> 00:28:30,519
<i>For now, we can only speculate,</i>
<i>but our search continues.</i>

318
00:28:30,687 --> 00:28:35,363
<i>And that means that one day,</i>
<i>we may actually find out.</i>