1
00:00:07,043 --> 00:00:09,643
[pensive music playing]

2
00:00:14,163 --> 00:00:15,163
[Freeman] Nightfall…

3
00:00:19,283 --> 00:00:22,923
reveals our planet's connection
to the universe.

4
00:00:26,523 --> 00:00:28,123
[whooshing]

5
00:00:28,203 --> 00:00:29,603
A shooting star.

6
00:00:31,243 --> 00:00:34,523
Ancient rock from the depths of space…

7
00:00:38,723 --> 00:00:39,923
falling to Earth.

8
00:00:50,363 --> 00:00:54,923
Inside it are the chemical elements
that built our universe.

9
00:00:55,003 --> 00:00:56,803
[pensive music continues]

10
00:01:02,243 --> 00:01:04,723
[ethereal tinkling]

11
00:01:10,523 --> 00:01:12,203
For countless generations,

12
00:01:13,043 --> 00:01:16,203
sea turtles have roamed the oceans,

13
00:01:16,803 --> 00:01:20,523
gathering cosmic elements
in the food they eat.

14
00:01:24,203 --> 00:01:27,763
And as they've done
for hundreds of millions of years…

15
00:01:33,923 --> 00:01:35,603
every new generation

16
00:01:37,563 --> 00:01:40,403
recycles this same stardust…

17
00:01:43,363 --> 00:01:45,243
to produce the next.

18
00:01:51,403 --> 00:01:53,763
-[fire roaring]
-[majestic music playing]

19
00:01:53,843 --> 00:01:55,443
Born in The Big Bang…

20
00:01:55,523 --> 00:01:56,803
[whooshing]

21
00:01:56,883 --> 00:01:59,443
…and forged in the hearts of stars…

22
00:01:59,523 --> 00:02:01,603
[whooshing, exploding]

23
00:02:01,683 --> 00:02:05,643
…90 chemical elements
have created everything.

24
00:02:08,163 --> 00:02:10,723
Endlessly recycled and reconfigured

25
00:02:11,723 --> 00:02:15,203
throughout the entire history
of the universe.

26
00:02:15,723 --> 00:02:17,083
[whooshing]

27
00:02:18,283 --> 00:02:19,523
And now…

28
00:02:21,683 --> 00:02:23,483
using the same elements,

29
00:02:24,803 --> 00:02:27,443
each new turtle begins a life cycle…

30
00:02:28,003 --> 00:02:32,723
-[zapping]
-[majestic music crescendos]

31
00:02:34,003 --> 00:02:37,643
…that mirrors the lives of the stars.

32
00:02:39,403 --> 00:02:41,843
[dramatic music playing]

33
00:03:07,523 --> 00:03:11,123
[calm music playing]

34
00:03:16,523 --> 00:03:18,363
[bird squawking]

35
00:03:18,443 --> 00:03:21,003
[Freeman]
On Australia's Great Barrier Reef…

36
00:03:27,323 --> 00:03:28,643
[squawking continues]

37
00:03:28,723 --> 00:03:31,163
…something magical has happened.

38
00:03:34,083 --> 00:03:36,323
[calm music continues]

39
00:03:37,923 --> 00:03:40,323
After 50 days beneath the sand,

40
00:03:41,523 --> 00:03:46,923
chemical elements
from across the cosmos have created life.

41
00:03:49,323 --> 00:03:52,523
Combining to form the next generation

42
00:03:53,523 --> 00:03:55,003
of green sea turtles.

43
00:03:56,923 --> 00:03:58,403
[egg rustling]

44
00:04:01,403 --> 00:04:03,843
[calm music continues]

45
00:04:09,163 --> 00:04:10,043
[egg cracking]

46
00:04:18,443 --> 00:04:22,443
The eggs have now exhausted their supply
of life-giving elements.

47
00:04:26,163 --> 00:04:29,163
[calm music continues]

48
00:04:39,803 --> 00:04:45,203
And today, the baby turtles
will take their first taste of air.

49
00:04:59,123 --> 00:05:03,043
And as her brothers and sisters
scramble to make it to the water…

50
00:05:08,643 --> 00:05:09,843
a little female…

51
00:05:12,603 --> 00:05:14,443
is last to be born.

52
00:05:20,163 --> 00:05:22,203
In order to grow to adulthood,

53
00:05:23,923 --> 00:05:27,763
she will need to harvest chemical elements
from across the ocean.

54
00:05:36,843 --> 00:05:38,443
It's a dangerous journey…

55
00:05:38,523 --> 00:05:41,083
[ominous music playing]

56
00:05:41,163 --> 00:05:43,323
…with treachery at every turn.

57
00:05:43,403 --> 00:05:45,723
[bird squawking]

58
00:05:50,443 --> 00:05:51,923
But for the baby turtles,

59
00:05:53,243 --> 00:05:56,403
the call of the ocean is irresistible.

60
00:06:01,083 --> 00:06:04,203
[birds squawking loudly]

61
00:06:04,283 --> 00:06:06,563
[ominous music continues]

62
00:06:09,883 --> 00:06:11,243
From a nest of 100,

63
00:06:12,363 --> 00:06:14,923
sometimes only one will survive.

64
00:06:18,723 --> 00:06:20,883
Sometimes none.

65
00:06:45,003 --> 00:06:47,523
[birds continue squawking]

66
00:06:51,003 --> 00:06:53,443
[suspenseful music playing]

67
00:07:13,603 --> 00:07:15,123
But despite the risk,

68
00:07:17,283 --> 00:07:19,083
the little female knows

69
00:07:19,603 --> 00:07:21,923
she must make it to the water.

70
00:07:23,523 --> 00:07:25,403
[birds squawking]

71
00:07:27,923 --> 00:07:29,763
[suspenseful music continues]

72
00:07:48,403 --> 00:07:50,523
[birds continue squawking]

73
00:07:51,683 --> 00:07:53,883
[suspenseful music continues]

74
00:07:59,923 --> 00:08:01,363
She spots an opening…

75
00:08:04,723 --> 00:08:05,963
and takes her chance.

76
00:08:09,043 --> 00:08:11,083
[pensive music playing]

77
00:08:20,923 --> 00:08:21,763
Today…

78
00:08:24,443 --> 00:08:25,763
she's a lucky one.

79
00:08:29,123 --> 00:08:34,443
The hatchling won't stop swimming
until she has left the reef far behind.

80
00:08:37,323 --> 00:08:39,923
[pensive music continues]

81
00:08:47,163 --> 00:08:51,563
Safely past the predators
that gather in the shallow coastal waters,

82
00:08:52,763 --> 00:08:55,963
she'll disappear into the great void
of the open ocean…

83
00:09:03,243 --> 00:09:07,643
to spend her childhood feeding on atoms.

84
00:09:10,163 --> 00:09:13,523
[whooshing, zapping]

85
00:09:14,283 --> 00:09:20,963
Atoms whose origins go back through
the entire life of the cosmos.

86
00:09:21,483 --> 00:09:24,243
[energetic rock music playing]

87
00:09:24,323 --> 00:09:26,083
[whooshing]

88
00:09:26,683 --> 00:09:30,083
To the time our universe

89
00:09:30,683 --> 00:09:32,483
was in its infancy.

90
00:09:39,003 --> 00:09:41,443
[pulsing]

91
00:09:41,523 --> 00:09:44,083
[whooshing]

92
00:09:48,043 --> 00:09:53,123
Expanding from nothing
to everything in an instant.

93
00:09:56,323 --> 00:09:59,843
Our universe was born in The Big Bang.

94
00:10:01,123 --> 00:10:03,843
[calm music playing]

95
00:10:07,443 --> 00:10:08,323
At first,

96
00:10:09,083 --> 00:10:11,843
it was nothing but a hot, dense fog.

97
00:10:13,323 --> 00:10:15,723
[wind howling]

98
00:10:19,123 --> 00:10:21,523
But as it continued to expand…

99
00:10:24,403 --> 00:10:26,043
the fog began to cool.

100
00:10:29,443 --> 00:10:32,083
And on the tiniest scale imaginable…

101
00:10:32,163 --> 00:10:33,563
[zapping]

102
00:10:33,643 --> 00:10:36,003
…something astounding began to occur.

103
00:10:36,083 --> 00:10:37,523
[pulsing]

104
00:10:37,603 --> 00:10:40,523
[uplifting music playing]

105
00:10:42,043 --> 00:10:45,443
The first atoms condensed out of the fog.

106
00:10:45,523 --> 00:10:47,723
[zapping]

107
00:10:50,163 --> 00:10:52,443
Atoms of hydrogen.

108
00:10:52,523 --> 00:10:55,443
[high-pitched squeaking]

109
00:10:56,083 --> 00:10:59,643
The very first element in the universe.

110
00:10:59,723 --> 00:11:01,923
[uplifting music continues]

111
00:11:06,683 --> 00:11:07,843
And in the ocean,

112
00:11:08,723 --> 00:11:11,963
juvenile turtles are hunting it down.

113
00:11:15,203 --> 00:11:17,523
As they emerge from the blue

114
00:11:17,603 --> 00:11:20,163
to forage in the shallow waters
of the reef.

115
00:11:24,963 --> 00:11:26,603
This is Stella.

116
00:11:27,803 --> 00:11:30,683
One of the lucky ones
that made it off the beach

117
00:11:31,323 --> 00:11:32,563
and into the ocean.

118
00:11:35,923 --> 00:11:38,723
[pensive music playing]

119
00:11:41,523 --> 00:11:44,723
She's already more than 2,000 times
her hatching weight

120
00:11:45,883 --> 00:11:46,923
and growing fast.

121
00:11:51,883 --> 00:11:55,403
Feeding on creatures she's found drifting
in the open ocean,

122
00:11:56,883 --> 00:11:59,923
she's harvested one element
more than any other.

123
00:12:01,363 --> 00:12:04,043
[majestic music playing]

124
00:12:08,683 --> 00:12:09,523
Hydrogen.

125
00:12:12,603 --> 00:12:16,843
It makes up more than half
of all the atoms in the food she eats.

126
00:12:20,843 --> 00:12:24,523
And is the most abundant element
in all living things.

127
00:12:28,643 --> 00:12:29,723
From fish

128
00:12:31,003 --> 00:12:32,243
to invertebrates.

129
00:12:39,003 --> 00:12:41,363
Anemones and coral.

130
00:12:54,483 --> 00:12:58,603
Hydrogen atoms formed
at the dawn of the universe

131
00:12:59,563 --> 00:13:03,243
have been passed on from star to planet,

132
00:13:04,363 --> 00:13:05,963
planet to animal…

133
00:13:08,363 --> 00:13:11,323
and from prey to predator.

134
00:13:13,363 --> 00:13:14,603
[Stella exhales sharply]

135
00:13:22,123 --> 00:13:23,523
Which means, for Stella,

136
00:13:24,323 --> 00:13:27,043
the waters around the reef
are full of danger.

137
00:13:28,043 --> 00:13:30,843
[suspenseful music playing]

138
00:13:30,923 --> 00:13:33,963
Tiger sharks, hungry for the same atoms,

139
00:13:34,043 --> 00:13:37,043
hunt sea turtles
throughout their adult lives.

140
00:13:45,323 --> 00:13:48,603
Stella's main defense is her trusty armor.

141
00:13:52,323 --> 00:13:55,323
Its bone toughened
with calcium and phosphorus.

142
00:13:56,763 --> 00:13:59,123
[suspenseful music continues]

143
00:14:02,363 --> 00:14:05,363
Elements that date back
to another pivotal moment…

144
00:14:09,443 --> 00:14:11,323
in the life of our universe.

145
00:14:12,643 --> 00:14:14,843
[ethereal music playing]

146
00:14:21,963 --> 00:14:25,723
For the first 300 million years
after The Big Bang…

147
00:14:28,123 --> 00:14:31,043
there are no planets and no stars.

148
00:14:34,123 --> 00:14:36,643
The dark ages of the universe.

149
00:14:37,243 --> 00:14:39,723
[ominous music playing]

150
00:14:42,403 --> 00:14:44,163
Concealed in the gloom,

151
00:14:44,683 --> 00:14:48,643
vast tendrils
of hydrogen gas crisscross the cosmos.

152
00:14:53,323 --> 00:14:55,603
And then, incredibly,

153
00:14:56,243 --> 00:14:58,723
as they were drawn together by gravity…

154
00:14:58,803 --> 00:15:00,643
[roaring]

155
00:15:02,443 --> 00:15:04,563
…the first stars were born.

156
00:15:05,083 --> 00:15:06,523
[zapping]

157
00:15:11,163 --> 00:15:13,043
This is the cosmic dawn.

158
00:15:13,123 --> 00:15:14,923
[ethereal music playing]

159
00:15:16,763 --> 00:15:20,923
The moment the lights came on.

160
00:15:21,003 --> 00:15:23,283
[buzzing]

161
00:15:24,883 --> 00:15:26,683
[crackling]

162
00:15:28,043 --> 00:15:30,723
And deep within those first stars…

163
00:15:34,923 --> 00:15:37,123
a remarkable process began.

164
00:15:37,203 --> 00:15:39,523
[ethereal music continues]

165
00:15:40,443 --> 00:15:42,763
[pulsing]

166
00:15:42,843 --> 00:15:46,123
Temperatures and pressures
were so extreme…

167
00:15:46,803 --> 00:15:48,043
[whooshing]

168
00:15:48,123 --> 00:15:50,403
…that new elements were created.

169
00:15:52,563 --> 00:15:56,443
Atoms of hydrogen
were forced together to make helium.

170
00:15:58,843 --> 00:16:01,923
As they fused, energy was released.

171
00:16:02,003 --> 00:16:03,163
[zapping]

172
00:16:04,563 --> 00:16:09,243
Creating a chain reaction that produced
increasingly heavier elements.

173
00:16:09,323 --> 00:16:11,123
[pulsing]

174
00:16:12,363 --> 00:16:15,683
Including those essential for life.

175
00:16:16,443 --> 00:16:17,603
[zapping]

176
00:16:17,683 --> 00:16:21,403
Three helium atoms combined
to make carbon.

177
00:16:21,483 --> 00:16:24,803
[dramatic music playing]

178
00:16:26,843 --> 00:16:29,523
The element on which all life is based.

179
00:16:31,803 --> 00:16:34,603
Carbon and helium made oxygen.

180
00:16:36,163 --> 00:16:37,443
The air we breathe.

181
00:16:37,523 --> 00:16:39,643
[intriguing music playing]

182
00:16:39,723 --> 00:16:42,923
Oxygen atoms combined to make phosphorus.

183
00:16:44,963 --> 00:16:47,203
Then silicon and calcium.

184
00:16:48,203 --> 00:16:49,283
[zapping]

185
00:16:50,243 --> 00:16:52,843
The elements
that make up every living thing

186
00:16:54,363 --> 00:16:58,843
were created in the hearts
of the very first stars.

187
00:16:59,603 --> 00:17:02,043
[dramatic music playing]

188
00:17:05,443 --> 00:17:07,723
[penguins chirping]

189
00:17:13,763 --> 00:17:15,043
[elephant huffing]

190
00:17:25,203 --> 00:17:26,643
[dramatic music crescendos]

191
00:17:31,043 --> 00:17:31,923
For Stella,

192
00:17:33,203 --> 00:17:35,083
some elements are so important…

193
00:17:35,163 --> 00:17:37,323
[pensive music playing]

194
00:17:38,643 --> 00:17:41,123
…she'll travel great distances
to find them.

195
00:17:51,643 --> 00:17:56,043
The warm, shallow waters
between Australia and Papua New Guinea

196
00:17:57,403 --> 00:17:59,843
are a paradise of vibrant seagrass.

197
00:18:01,323 --> 00:18:04,163
[intriguing music playing]

198
00:18:04,243 --> 00:18:06,723
The prairies of the ocean.

199
00:18:16,163 --> 00:18:22,003
Stella has traveled all the way here
to access their magic ingredients.

200
00:18:27,963 --> 00:18:29,483
[whooshing]

201
00:18:32,603 --> 00:18:34,043
As it grows,

202
00:18:34,123 --> 00:18:37,243
seagrass absorbs elements from outer space

203
00:18:37,963 --> 00:18:40,723
that have found their way
to the ocean floor.

204
00:18:43,923 --> 00:18:48,083
Burgeoning fronds
rich in calcium and phosphorus

205
00:18:49,803 --> 00:18:53,323
provide Stella
with precisely the minerals she needs

206
00:18:55,123 --> 00:18:58,363
to build and sustain her protective shell.

207
00:18:58,443 --> 00:19:00,963
[intriguing music continues]

208
00:19:01,923 --> 00:19:06,043
Hardening her armor for the trials ahead.

209
00:19:14,443 --> 00:19:17,003
Stella will spend her adolescent years

210
00:19:17,723 --> 00:19:19,243
searching the ocean

211
00:19:20,963 --> 00:19:24,283
for atoms born in the stars.

212
00:19:24,923 --> 00:19:27,923
[intriguing music swells]

213
00:19:33,283 --> 00:19:35,123
Her journey toward maturity…

214
00:19:37,363 --> 00:19:40,843
paralleled in the story of our universe.

215
00:19:42,843 --> 00:19:45,643
[whooshing]

216
00:19:45,723 --> 00:19:48,963
Because three billion years
after The Big Bang…

217
00:19:52,003 --> 00:19:53,843
[ethereal music playing]

218
00:19:53,923 --> 00:19:56,723
…the universe was also coming of age.

219
00:20:02,683 --> 00:20:08,483
It was entering an incredibly active phase
of star formation.

220
00:20:10,603 --> 00:20:12,163
[pulsing]

221
00:20:12,243 --> 00:20:13,283
As they grew,

222
00:20:14,003 --> 00:20:17,323
stars were pulled together
into vast galaxies.

223
00:20:20,123 --> 00:20:21,843
Like our Milky Way.

224
00:20:21,923 --> 00:20:24,963
[dramatic music playing]

225
00:20:25,043 --> 00:20:26,923
And within those galaxies,

226
00:20:28,203 --> 00:20:30,883
the chemical elements each star produced…

227
00:20:30,963 --> 00:20:33,203
[whooshing]

228
00:20:34,563 --> 00:20:41,003
…were transformed into planets and moons.

229
00:20:46,683 --> 00:20:48,923
[dramatic music continues]

230
00:20:49,963 --> 00:20:51,523
After billions of years,

231
00:20:53,363 --> 00:20:58,923
chemical elements have matured
into the Earth we know today.

232
00:21:23,123 --> 00:21:25,843
Stella is now fully grown herself.

233
00:21:25,923 --> 00:21:29,123
[ethereal music playing]

234
00:21:29,923 --> 00:21:31,283
Over a meter long,

235
00:21:32,323 --> 00:21:35,643
she has a thick shell
covered in green algae.

236
00:21:39,283 --> 00:21:42,443
Ideal camouflage for cruising coral reefs.

237
00:21:46,643 --> 00:21:49,163
She is now at one with the ocean.

238
00:21:55,843 --> 00:21:57,483
Atoms from the stars

239
00:21:59,363 --> 00:22:02,643
perfectly adapted to life at sea.

240
00:22:03,123 --> 00:22:05,723
[ethereal music continues]

241
00:22:11,043 --> 00:22:13,163
Just one example of life on Earth…

242
00:22:15,323 --> 00:22:18,363
exquisitely shaped from the cosmos.

243
00:22:35,603 --> 00:22:39,043
Stella is now ready
for the next stage of her life.

244
00:22:39,123 --> 00:22:41,523
[ethereal music continues]

245
00:22:43,723 --> 00:22:47,043
Because she's about
to become a mother herself.

246
00:22:50,243 --> 00:22:51,363
Inside her body…

247
00:22:54,003 --> 00:22:56,523
she's carrying a clutch of 100 eggs.

248
00:22:58,323 --> 00:23:01,123
The first of many
she'll have over her lifetime.

249
00:23:03,723 --> 00:23:07,923
Her own precious cargo of stardust.

250
00:23:15,803 --> 00:23:17,163
All across the reef,

251
00:23:18,403 --> 00:23:20,763
atoms are being assembled into new life.

252
00:23:25,523 --> 00:23:30,203
Creating one of the richest ecosystems
on Earth.

253
00:23:35,963 --> 00:23:38,043
But our planet…

254
00:23:38,123 --> 00:23:40,003
[whooshing]

255
00:23:41,363 --> 00:23:42,443
…is an outlier.

256
00:23:45,003 --> 00:23:47,163
In the rest of the solar system,

257
00:23:47,243 --> 00:23:49,203
the very same elements

258
00:23:49,283 --> 00:23:54,043
have created worlds
far less suited to life.

259
00:23:54,123 --> 00:23:57,003
[whooshing]

260
00:23:57,083 --> 00:23:58,443
[eerie music playing]

261
00:23:59,963 --> 00:24:01,363
Closest to the sun,

262
00:24:02,123 --> 00:24:05,043
Mercury is a planet rich in carbon.

263
00:24:05,763 --> 00:24:07,843
[fizzling]

264
00:24:07,923 --> 00:24:09,723
But rather than creating life,

265
00:24:11,603 --> 00:24:13,843
the carbon is baked into its crust.

266
00:24:16,203 --> 00:24:19,963
On a world scorched by starlight.

267
00:24:20,563 --> 00:24:22,083
[whooshing]

268
00:24:22,563 --> 00:24:26,483
While in the farthest reaches
of the solar system,

269
00:24:26,563 --> 00:24:28,603
Neptune's freezing temperatures

270
00:24:29,523 --> 00:24:33,563
cause carbon and hydrogen
to form clouds of methane.

271
00:24:33,643 --> 00:24:34,963
[wind gusting]

272
00:24:36,723 --> 00:24:40,923
The suffocating gas
that gives it its brilliant blue.

273
00:24:42,163 --> 00:24:45,723
[whooshing]

274
00:24:46,683 --> 00:24:48,003
And even on Mars,

275
00:24:49,203 --> 00:24:52,003
a planet with all the same ingredients
as Earth…

276
00:24:54,363 --> 00:24:56,923
the lack of an oxygen-rich atmosphere

277
00:24:57,563 --> 00:25:00,923
means complex life couldn't survive here.

278
00:25:02,883 --> 00:25:05,243
[eerie music continues]

279
00:25:07,843 --> 00:25:12,123
Only on Earth are conditions just right.

280
00:25:18,363 --> 00:25:19,363
But even here,

281
00:25:20,163 --> 00:25:22,323
competition for elements is fierce.

282
00:25:24,243 --> 00:25:25,083
And danger…

283
00:25:25,163 --> 00:25:27,523
[ominous music playing]

284
00:25:27,603 --> 00:25:29,083
…is never far away.

285
00:25:44,923 --> 00:25:48,443
Luckily, Stella has become
an expert at hide-and-seek.

286
00:25:48,523 --> 00:25:50,923
[ominous music continues]

287
00:26:05,603 --> 00:26:07,843
[ominous music intensifies]

288
00:26:25,043 --> 00:26:27,323
[calm music playing]

289
00:26:29,963 --> 00:26:31,443
Safe for now…

290
00:26:34,363 --> 00:26:37,363
Stella faces the biggest challenge
of her life.

291
00:26:39,563 --> 00:26:42,323
To return to the Great Barrier Reef

292
00:26:43,963 --> 00:26:45,643
and the island of her birth…

293
00:26:49,523 --> 00:26:51,923
to lay her own eggs in the sand.

294
00:26:58,923 --> 00:27:01,483
But a lifetime spent wandering the ocean

295
00:27:02,243 --> 00:27:05,643
means she's now 2,000 kilometers away.

296
00:27:05,723 --> 00:27:08,083
[calm music continues]

297
00:27:09,883 --> 00:27:11,563
How Stella navigates home

298
00:27:12,203 --> 00:27:14,803
is one of the wonders
of the natural world.

299
00:27:19,923 --> 00:27:21,363
[humming]

300
00:27:21,443 --> 00:27:22,803
Deep within the Earth,

301
00:27:23,643 --> 00:27:26,643
our planet's core generates
a magnetic field…

302
00:27:28,883 --> 00:27:33,923
which gives every place on its surface
a unique magnetic signature.

303
00:27:34,923 --> 00:27:36,643
[intriguing music playing]

304
00:27:37,603 --> 00:27:39,163
When she hatched,

305
00:27:39,243 --> 00:27:43,563
her island's signature
was imprinted in Stella's brain.

306
00:27:46,243 --> 00:27:48,243
And to find her way back,

307
00:27:48,323 --> 00:27:51,643
she'll rely on
yet another chemical element.

308
00:27:53,803 --> 00:27:56,923
One that connects her
to the planet's core.

309
00:28:00,443 --> 00:28:05,123
An element that's only created
when stars die.

310
00:28:08,443 --> 00:28:10,643
[ethereal music playing]

311
00:28:10,723 --> 00:28:12,763
In a nearby part of the galaxy,

312
00:28:13,763 --> 00:28:15,723
two and a half million years ago,

313
00:28:16,763 --> 00:28:20,563
a dramatic change took place
in the core of a giant star.

314
00:28:21,283 --> 00:28:23,523
[hissing]

315
00:28:25,323 --> 00:28:29,403
For all its life,
it had been powered by nuclear fusion.

316
00:28:30,403 --> 00:28:31,763
[pulsing]

317
00:28:35,923 --> 00:28:37,243
The energy released…

318
00:28:37,323 --> 00:28:39,003
[zapping]

319
00:28:39,083 --> 00:28:41,483
…creating heavier and heavier elements.

320
00:28:42,363 --> 00:28:44,523
[whooshing]

321
00:28:45,243 --> 00:28:48,163
Until the core became so hot,

322
00:28:48,683 --> 00:28:49,923
it started creating…

323
00:28:50,003 --> 00:28:51,603
[whooshing, zapping]

324
00:28:51,683 --> 00:28:52,523
…iron.

325
00:28:55,403 --> 00:28:58,243
Which caused a fundamental change
to take place.

326
00:29:00,003 --> 00:29:02,323
[whooshing, zapping]

327
00:29:03,123 --> 00:29:06,403
Because making iron
doesn't release energy.

328
00:29:07,923 --> 00:29:09,203
It consumes it.

329
00:29:10,123 --> 00:29:11,723
[cracking]

330
00:29:15,923 --> 00:29:18,403
As more and more
of the metal was produced,

331
00:29:19,283 --> 00:29:22,803
it spread through the core like a disease.

332
00:29:27,203 --> 00:29:29,203
Feeding off the star's heat.

333
00:29:29,283 --> 00:29:31,723
[cracking rapidly]

334
00:29:33,923 --> 00:29:34,923
Throttling it.

335
00:29:39,283 --> 00:29:41,443
[ethereal music continues]

336
00:29:41,523 --> 00:29:43,843
[cracking continues]

337
00:29:46,323 --> 00:29:48,603
With no heat source to hold it up.

338
00:29:49,443 --> 00:29:51,803
[gurgling]

339
00:29:52,883 --> 00:29:54,443
From this moment onward…

340
00:29:55,723 --> 00:29:57,443
[ethereal tinkling]

341
00:29:57,523 --> 00:29:59,723
…the star was doomed.

342
00:29:59,803 --> 00:30:02,203
[rumbling]

343
00:30:03,283 --> 00:30:05,723
[booming, ringing]

344
00:30:11,643 --> 00:30:16,243
The resulting explosion shone
with the brightness of 10 billion suns.

345
00:30:16,323 --> 00:30:20,043
[whooshing, zapping]

346
00:30:20,123 --> 00:30:21,963
[rumbling]

347
00:30:22,043 --> 00:30:27,123
A supernova which propelled
iron-rich dust across the galaxy.

348
00:30:27,203 --> 00:30:30,043
[wind whipping]

349
00:30:30,123 --> 00:30:32,683
[ethereal music playing]

350
00:30:35,163 --> 00:30:38,163
All the way to our planet.

351
00:30:43,203 --> 00:30:44,323
And even now,

352
00:30:45,323 --> 00:30:50,323
100 tons of stardust enters
Earth's atmosphere every day.

353
00:30:53,123 --> 00:30:56,843
Some left over
from the formation of the solar system.

354
00:30:56,923 --> 00:30:59,083
[ethereal tinkling]

355
00:31:00,643 --> 00:31:04,523
Some blown here from distant supernovas.

356
00:31:08,443 --> 00:31:13,643
A direct link
between our planet and the stars.

357
00:31:14,403 --> 00:31:16,723
[ethereal music continues]

358
00:31:19,723 --> 00:31:22,003
And it's the iron in this dust

359
00:31:22,563 --> 00:31:25,443
that allows Stella to find her way.

360
00:31:25,523 --> 00:31:28,443
[ethereal tinkling]

361
00:31:33,563 --> 00:31:35,243
Because deep in her brain…

362
00:31:35,323 --> 00:31:37,003
[whooshing]

363
00:31:37,083 --> 00:31:38,243
[pulsing]

364
00:31:38,323 --> 00:31:43,643
…specialized cells are thought
to contain crystals of magnetite.

365
00:31:44,563 --> 00:31:48,803
An iron-rich mineral that aligns itself
to the Earth's magnetic field.

366
00:31:48,883 --> 00:31:51,723
[intriguing music playing]

367
00:31:52,803 --> 00:31:53,723
A compass,

368
00:31:55,603 --> 00:31:57,723
pointing her in the right direction.

369
00:32:05,483 --> 00:32:11,723
Allowing Stella to find
the unique magnetic fingerprint of home.

370
00:32:13,763 --> 00:32:16,083
[intriguing music continues]

371
00:32:19,523 --> 00:32:22,723
And so an element forged in a supernova…

372
00:32:22,803 --> 00:32:25,323
[ethereal music playing]

373
00:32:30,403 --> 00:32:34,323
…will now guide her across kilometers
of featureless ocean.

374
00:32:48,643 --> 00:32:49,963
Back to the island…

375
00:32:53,843 --> 00:32:55,523
on which she was born.

376
00:33:08,163 --> 00:33:12,083
But there are other creatures
with magnetic homing abilities.

377
00:33:12,603 --> 00:33:14,643
[ominous music playing]

378
00:33:14,723 --> 00:33:16,523
The tiger sharks have it too.

379
00:33:19,643 --> 00:33:22,323
And it's leading them back
to the same island.

380
00:33:26,603 --> 00:33:28,963
Because for a few months every year,

381
00:33:29,043 --> 00:33:32,643
thousands of female turtles come here
to lay their eggs.

382
00:33:34,643 --> 00:33:37,923
It's the largest gathering
of green sea turtles

383
00:33:38,003 --> 00:33:40,003
anywhere on the planet.

384
00:33:41,683 --> 00:33:43,443
[ominous music continues]

385
00:33:45,643 --> 00:33:47,363
And as they come to shore,

386
00:33:49,123 --> 00:33:50,363
the feeding begins.

387
00:33:50,443 --> 00:33:52,123
[ominous music crescendos]

388
00:33:57,323 --> 00:34:00,163
[tense music playing]

389
00:34:03,843 --> 00:34:06,203
Stella must wait for the right moment…

390
00:34:08,883 --> 00:34:10,083
to find an opening…

391
00:34:12,203 --> 00:34:14,123
and avoid the onslaught.

392
00:34:14,643 --> 00:34:17,123
[tense music continues]

393
00:34:21,843 --> 00:34:24,523
[calm music playing]

394
00:34:27,723 --> 00:34:30,963
[birds squawking]

395
00:34:32,123 --> 00:34:33,843
When the danger has passed…

396
00:34:37,483 --> 00:34:39,123
she finally swims ashore.

397
00:34:43,723 --> 00:34:46,443
[triumphant music playing]

398
00:34:52,323 --> 00:34:53,923
After an epic journey…

399
00:34:57,123 --> 00:34:59,283
Stella emerges onto the sand

400
00:35:00,883 --> 00:35:03,363
she last touched as a hatchling.

401
00:35:08,883 --> 00:35:11,963
[triumphant music continues]

402
00:35:28,083 --> 00:35:30,963
The elements she spent
a lifetime collecting…

403
00:35:36,643 --> 00:35:39,203
are now safely delivered into the sand.

404
00:35:45,283 --> 00:35:47,003
Stella's mission is complete,

405
00:35:47,563 --> 00:35:49,283
and she returns to the ocean…

406
00:35:52,923 --> 00:35:56,643
to begin gathering stardust once more.

407
00:36:00,523 --> 00:36:01,843
The cycle of her life

408
00:36:03,683 --> 00:36:06,563
mirroring the grandest cycle of all.

409
00:36:08,483 --> 00:36:11,963
The lives and deaths of the stars.

410
00:36:13,123 --> 00:36:15,523
[ethereal music playing]

411
00:36:22,523 --> 00:36:25,643
Because far away across the galaxy,

412
00:36:27,043 --> 00:36:29,723
the ashes of countless supernovas

413
00:36:29,803 --> 00:36:34,523
have come together to form a giant nebula.

414
00:36:34,603 --> 00:36:37,323
[ethereal tinkling]

415
00:36:41,323 --> 00:36:44,523
A cloud of stardust
tens of light-years across.

416
00:36:48,163 --> 00:36:52,643
And buried within it are places
where the next generation of stars

417
00:36:53,883 --> 00:36:55,323
are beginning to form.

418
00:36:55,403 --> 00:36:57,803
[ethereal music continues]

419
00:37:06,843 --> 00:37:08,443
Called proplyds.

420
00:37:10,443 --> 00:37:12,923
They're like vast cosmic eggs.

421
00:37:15,043 --> 00:37:17,723
Each one bigger than our solar system.

422
00:37:23,763 --> 00:37:26,683
Inside their shells of ionized gas,

423
00:37:28,603 --> 00:37:31,523
the force of gravity
is pulling stardust together.

424
00:37:33,123 --> 00:37:35,923
[whooshing]

425
00:37:38,923 --> 00:37:42,443
And the stardust inside Stella's eggs…

426
00:37:45,483 --> 00:37:47,603
is also beginning to take shape.

427
00:37:47,683 --> 00:37:50,083
[ethereal music continues]

428
00:37:51,763 --> 00:37:54,363
[heartbeat thumping]

429
00:37:56,243 --> 00:38:01,843
As the elements she collected
are being transformed…

430
00:38:08,323 --> 00:38:11,843
into something that's starting
to resemble a tiny creature.

431
00:38:18,283 --> 00:38:21,323
[dramatic music playing]

432
00:38:24,323 --> 00:38:25,683
And within the proplyd…

433
00:38:27,883 --> 00:38:30,283
gases like hydrogen and helium…

434
00:38:31,883 --> 00:38:33,083
[rumbling]

435
00:38:33,163 --> 00:38:35,723
…are feeding an embryonic star.

436
00:38:39,203 --> 00:38:42,043
[dramatic music continues]

437
00:38:44,923 --> 00:38:46,723
And what was once an embryo…

438
00:38:49,123 --> 00:38:51,123
is now a tiny turtle…

439
00:38:55,243 --> 00:38:58,923
with shell, flippers, and beak.

440
00:39:02,923 --> 00:39:04,723
Elements reimagined…

441
00:39:08,123 --> 00:39:10,323
for a life at sea.

442
00:39:10,403 --> 00:39:12,723
[heartbeat thumping]

443
00:39:15,203 --> 00:39:16,163
In the proplyd,

444
00:39:17,043 --> 00:39:20,243
the new star's development
is also nearing completion.

445
00:39:21,523 --> 00:39:24,843
Reborn from the ashes
of the previous generation,

446
00:39:26,163 --> 00:39:30,043
its light now reveals a family
of growing planets in orbit.

447
00:39:34,243 --> 00:39:35,363
New worlds.

448
00:39:36,283 --> 00:39:40,323
But perhaps, new possibilities for life.

449
00:39:41,723 --> 00:39:44,163
[dramatic music continues]

450
00:39:48,323 --> 00:39:49,963
And beneath the sand,

451
00:39:51,283 --> 00:39:52,803
the same stardust,

452
00:39:54,123 --> 00:39:58,843
passed down through countless generations
of stars and turtles…

453
00:40:00,923 --> 00:40:03,243
will start yet another journey.

454
00:40:07,043 --> 00:40:08,123
[egg cracking]

455
00:40:08,203 --> 00:40:09,603
Each new life

456
00:40:11,123 --> 00:40:15,443
directly connected
to the origin of the universe.

457
00:40:18,723 --> 00:40:20,803
[dramatic music crescendos]

458
00:40:20,883 --> 00:40:26,443
Each new story beginning
at the end of the last.

459
00:40:31,203 --> 00:40:33,963
-[thunder rumbling]
-[lightning zapping]

460
00:40:34,923 --> 00:40:38,923
And so,
the story of our universe continues…

461
00:40:39,003 --> 00:40:40,723
[ethereal tinkling]

462
00:40:40,803 --> 00:40:43,043
…with Earth's most precious resource…

463
00:40:43,123 --> 00:40:45,283
[ethereal music playing]

464
00:40:46,323 --> 00:40:47,163
…water.

465
00:40:48,963 --> 00:40:52,843
And a family of elephants
on a dangerous mission to find it.

466
00:40:54,363 --> 00:40:55,483
[elephant huffing]

467
00:40:57,043 --> 00:40:59,403
Their journey every bit as extraordinary…

468
00:40:59,483 --> 00:41:01,123
[lion growls]

469
00:41:01,723 --> 00:41:06,483
…as water's journey across the vastness
of space to our planet.

470
00:41:10,683 --> 00:41:13,883
But why is Earth the only world
in the solar system

471
00:41:14,883 --> 00:41:17,283
whose surface
is covered with liquid water?

472
00:41:18,643 --> 00:41:22,003
And why is it so essential for life?

473
00:41:22,723 --> 00:41:23,963
[elephant trumpets]

474
00:41:26,123 --> 00:41:29,723
[dramatic music playing]