[Script Info]
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[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:06.89,0:00:09.49,Default,,0000,0000,0000,,Humans have observed comets \Nfor thousands of years
Dialogue: 0,0:00:09.49,0:00:13.26,Default,,0000,0000,0000,,as their orbits have brought them within\Nvisible distance of Earth.
Dialogue: 0,0:00:13.26,0:00:15.24,Default,,0000,0000,0000,,Appearing throughout historical records,\N
Dialogue: 0,0:00:15.24,0:00:17.78,Default,,0000,0000,0000,,these mysterious lights that \Ncame out of nowhere
Dialogue: 0,0:00:17.78,0:00:19.88,Default,,0000,0000,0000,,and disappeared after a short while
Dialogue: 0,0:00:19.88,0:00:22.70,Default,,0000,0000,0000,,were thought to be ill omens of\Nwar and famine,
Dialogue: 0,0:00:22.70,0:00:24.43,Default,,0000,0000,0000,,or the wrath of gods.
Dialogue: 0,0:00:24.43,0:00:28.60,Default,,0000,0000,0000,,But recent research has revealed that\Ncomets may be even more deeply connected
Dialogue: 0,0:00:28.60,0:00:30.58,Default,,0000,0000,0000,,to humanity and our presence on Earth
Dialogue: 0,0:00:30.58,0:00:34.12,Default,,0000,0000,0000,,than any of these mythical \Nexplanations suggested.
Dialogue: 0,0:00:34.12,0:00:37.38,Default,,0000,0000,0000,,When you think of our Solar System,\Nyou probably imagine the nine,
Dialogue: 0,0:00:37.38,0:00:40.59,Default,,0000,0000,0000,,sorry eight, planets orbiting the Sun.
Dialogue: 0,0:00:40.59,0:00:43.82,Default,,0000,0000,0000,,But beyond Neptune,\Nfar from the heat of the Sun,
Dialogue: 0,0:00:43.82,0:00:46.48,Default,,0000,0000,0000,,there is a sparse ring found \Nformed by icy chunks
Dialogue: 0,0:00:46.48,0:00:50.66,Default,,0000,0000,0000,,ranging from the size \Nof marbles to that of small planets.
Dialogue: 0,0:00:50.66,0:00:54.15,Default,,0000,0000,0000,,And thousands of times farther at the\Nouter reaches of the Solar System
Dialogue: 0,0:00:54.15,0:00:57.83,Default,,0000,0000,0000,,lies a spherical cloud of small \Nfragments and gases.
Dialogue: 0,0:00:57.83,0:01:01.27,Default,,0000,0000,0000,,Many of these ancient clumps of stardust\Nare leftovers from the formation
Dialogue: 0,0:01:01.27,0:01:05.01,Default,,0000,0000,0000,,of the Solar System 4.6 billion years ago,
Dialogue: 0,0:01:05.01,0:01:09.26,Default,,0000,0000,0000,,while some of the most distant may even\Ncome from a neighboring system.
Dialogue: 0,0:01:09.26,0:01:12.34,Default,,0000,0000,0000,,But sometimes the gravity from \Npassing planets or stars
Dialogue: 0,0:01:12.34,0:01:14.38,Default,,0000,0000,0000,,pulls them toward our sun,
Dialogue: 0,0:01:14.38,0:01:17.77,Default,,0000,0000,0000,,beginning a journey that can take up to\Nmillions of years.
Dialogue: 0,0:01:17.77,0:01:21.20,Default,,0000,0000,0000,,As the frozen object travels further\Ninto the Solar System,
Dialogue: 0,0:01:21.20,0:01:24.01,Default,,0000,0000,0000,,the sun grows from a distant spark\Nto an inferno,
Dialogue: 0,0:01:24.01,0:01:27.61,Default,,0000,0000,0000,,melting the ice for the first time\Nin billions of years.
Dialogue: 0,0:01:27.61,0:01:29.86,Default,,0000,0000,0000,,Gas and steam eject dust into space,
Dialogue: 0,0:01:29.86,0:01:32.88,Default,,0000,0000,0000,,forming a bright surrounding cloud,\Ncalled a coma,
Dialogue: 0,0:01:32.88,0:01:35.97,Default,,0000,0000,0000,,that can grow even larger than\Nthe sun itself.
Dialogue: 0,0:01:35.97,0:01:38.84,Default,,0000,0000,0000,,Meanwhile, the intense stream of \Nhigh-energy particles
Dialogue: 0,0:01:38.84,0:01:42.33,Default,,0000,0000,0000,,constantly emitted by the Sun,\Nknown as the solar wind,
Dialogue: 0,0:01:42.33,0:01:45.07,Default,,0000,0000,0000,,blows particles away from \Nthe comet's core,
Dialogue: 0,0:01:45.07,0:01:48.79,Default,,0000,0000,0000,,forming a trail of debris up to millions\Nof miles long.
Dialogue: 0,0:01:48.79,0:01:52.60,Default,,0000,0000,0000,,The ice, gas and dust reflect \Nlight glowing brightly.
Dialogue: 0,0:01:52.60,0:01:56.40,Default,,0000,0000,0000,,A comet is born, now orbiting the sun\Nalong with the rest of the objects
Dialogue: 0,0:01:56.40,0:01:58.80,Default,,0000,0000,0000,,in our Solar System.
Dialogue: 0,0:01:58.80,0:02:01.32,Default,,0000,0000,0000,,But as the comet travels through\Nthe Solar System,
Dialogue: 0,0:02:01.32,0:02:06.90,Default,,0000,0000,0000,,the solar wind tears apart and recombines\Nmolecules into various compounds.
Dialogue: 0,0:02:06.90,0:02:09.46,Default,,0000,0000,0000,,In some of the compounds that\Nscientists found,
Dialogue: 0,0:02:09.46,0:02:13.98,Default,,0000,0000,0000,,first in the rubble left by a meteorite\Nthat disintegrated above northern Canada,
Dialogue: 0,0:02:13.98,0:02:17.90,Default,,0000,0000,0000,,and then in samples collected by a space\Ncraft from a passing comet's tail,
Dialogue: 0,0:02:17.90,0:02:21.32,Default,,0000,0000,0000,,were nothing less important than\Namino acids.
Dialogue: 0,0:02:21.32,0:02:25.91,Default,,0000,0000,0000,,Coming together to form proteins\Naccording to the instructs encoded in DNA,
Dialogue: 0,0:02:25.91,0:02:29.15,Default,,0000,0000,0000,,these are the main active components\Nin all living cells,
Dialogue: 0,0:02:29.15,0:02:31.45,Default,,0000,0000,0000,,from bacteria to blue whales.
Dialogue: 0,0:02:31.45,0:02:35.20,Default,,0000,0000,0000,,If comets are where these building blocks\Nof life were first formed,
Dialogue: 0,0:02:35.20,0:02:37.84,Default,,0000,0000,0000,,then they are the ultimate source of\Nlife on Earth,
Dialogue: 0,0:02:37.84,0:02:41.48,Default,,0000,0000,0000,,and, perhaps, some of the other places\Nthey visited as well.
Dialogue: 0,0:02:41.48,0:02:44.76,Default,,0000,0000,0000,,We know that planets orbit nearly every\Nstar in the night sky,
Dialogue: 0,0:02:44.76,0:02:49.49,Default,,0000,0000,0000,,with one in five having a planet\Nsimilar to Earth in size and temperature.
Dialogue: 0,0:02:49.49,0:02:53.70,Default,,0000,0000,0000,,If Earth-like planets and the molecules\Nfound in DNA are not anomalies,
Dialogue: 0,0:02:53.70,0:02:56.19,Default,,0000,0000,0000,,we may be only one \Nexample of what's possible
Dialogue: 0,0:02:56.19,0:03:00.34,Default,,0000,0000,0000,,when a planet under the right conditions\Nis seeded with organic molecules
Dialogue: 0,0:03:00.34,0:03:02.12,Default,,0000,0000,0000,,by a passing comet.
Dialogue: 0,0:03:02.12,0:03:04.27,Default,,0000,0000,0000,,So, rather than an omen of death,
Dialogue: 0,0:03:04.27,0:03:06.86,Default,,0000,0000,0000,,the comet that first brought \Namino acids to Earth
Dialogue: 0,0:03:06.86,0:03:09.44,Default,,0000,0000,0000,,could have been a portent of life,
Dialogue: 0,0:03:09.44,0:03:12.88,Default,,0000,0000,0000,,a prediction of a distant future,\Nwhere creatures of stardust
Dialogue: 0,0:03:12.88,0:03:17.26,Default,,0000,0000,0000,,would return to space to find \Nthe mysteries of where they came from.