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On January, the second, 1959,
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with the space age barely a year old,
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the Soviet Union launched
Lunic, or little moon.
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It should have been the first
probe to land on the moon.
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But within hours of the
launch, it became clear
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that Lunic was going to miss its target.
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As the Soviet scientists watched
their tiny probe sail away,
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they renamed it Mechta, the dream.
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It was headed on a unique
journey around the sun
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to join the planets of our solar system.
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In 1926, when this recording
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of Holst's Planet Suite was made,
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there were thought to be eight planets.
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Then, in 1929, a young man
arrived at an observatory
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in Flagstaff, Arizona, to
start a search for a ninth.
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At that time, little was
known about the planets.
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Closest to the Sun, lies Mercury.
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A tiny world of iron and rock,
barely visible in the glare.
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Then, Venus. Perhaps a second Earth.
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Hidden beneath a blanket of cloud.
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Then, Earth. And beyond
us, Mars, the red planet.
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It has seasons, polar caps,
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and even the possibility of life.
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Far beyond these rocky worlds
are the distant giants.
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Jupiter, over a thousand
times bigger than the Earth.
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And Saturn, with its distinctive
and dramatic rings.
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The two remaining planets are 15 times
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the size of the earth,
yet they're so distant,
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they appear as the faintest of stars.
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Uranus, an aqua-marine
mystery and finally Neptune.
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A world that moves unevenly across the sky.
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This irregular movement
suggested the presence
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of a more distant planet, who's
faint gravitational pull
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might be toying with Neptune's orbit.
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Planet X.
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February the 18th, 1930,
Clyde Tombaugh sitting
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in an office very near to where
we're sitting right now,
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looking at the photographs
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that he had taken of the night sky.
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Sitting where this eye at the eyepiece
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at that blink comparator back there.
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And he had been searching on the plates
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that had been centered on a
star in the constellation
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of Gemeni, the twins, it
started that morning.
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He had moved very closely,
very slowly across
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and he would click, click,
click, moving, seeing one
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image then the other, then the other,
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keeping on moving back.
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All of these images were negatives
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so all of the stars, and anything else,
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would be black on a white background.
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About four o'clock that
afternoon, he crossed the very
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center of the plate, he
passed the area right
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where the guide star was,
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the star Delta Geminorum,
big, big, bright star.
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And moved a little bit
more, a little bit more,
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and then he saw a very faint,
a very faint black dot.
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And then he blinked to the other one,
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and it appeared on the other plate,
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and he saw it appear
here, and appear there.
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On his plates, taken several days apart,
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Tombaugh noticed that a
point of light had moved.
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He knew instantly, that this
was what he was looking for.
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It was an historic moment.
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He took the walk from the comparitor room,
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all the way to the director's office,
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and he stopped and he did his tie,
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and combed his hair a little bit,
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and he said I wanted to appear
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a little nonchalant about this.
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So then he stepped into the office,
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Dr. Slifer, I have found your Planet X.
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Planet X was soon named Pluto.
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It marks the end of the solar system.
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A tiny world of ice, smaller than our moon.
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Now known to have it's
own satellite, Charron.
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Pluto patrols the outer
edge of the solar system
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in the distant realm of giants.
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Worlds of swirling water,
like the az-u-an Neptune,
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and Uranus, which
mysteriously orbits the Sun,
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spinning on its back.
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Pluto lies way beyond
the gargantuan worlds,
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the gas planets that have no landscapes.
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Saturn with wind reaching
thousands of kilometers per hour
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and Jupiter, which has an Earth sized storm
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that has lasted for centuries.
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The closest worlds to the Sun,
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are small islands of rock and iron.
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Mars, with its faint
atmosphere of carbon dioxide
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and Venus, smothered in
clouds of sulfuric acid.
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Then there is Mercury,
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boiling in sunlight and freezing at night.
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Nine different worlds that
appear to have little in common,
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except that they orbit a single sun
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and are bound together by its gravity.
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And then, there's the Earth.
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One of the smallest planets
in our solar system.
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It has a thin atmosphere that
clings to a rocky surface.
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But the Earth is different, it is special.
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It has life.
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What process could create such
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a variety of different worlds?
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Hal Levison is at the forefront of a branch
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of astrophysics that is still
struggling with the mystery
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of how the planets formed.
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It's amazing to really consider
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that all the planets in the solar system,
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the Earth, the rest of the rocky planets,
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the cores of the giant
planets, Jupiter and Saturn,
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and the majority of the outer planets,
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Uranus, Neptune, and Pluto
formed from material
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that is very fine pieces of dust,
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much finer than the dust
that I'm holding in my hand.
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About the consistency, or size,
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of particles of dust in cigarette smoke.
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I was an astrophysicist
interested in a sort of obscure
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type of galaxy, when about
five years ago I got the bug
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of trying to understand
how material like this,
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can form the planets that we see today.
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By the 18th century,
astronomers had discovered
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that galaxies are filled
with drifting clouds of gas,
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called nebuli.
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Perhaps these clouds were the
raw materials of the planets.
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Two men, the philosopher Immanuel Kant,
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and the mathematician, Simon de Laplace,
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looked at how all the planets seemed
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to orbit in the same direction.
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They suggested the planets were a relic
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of a cloud of dust and gas that circled
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the Sun during its formation.
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In a single process, they concluded,
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the solar system was born.
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The idea was elegant and quite brilliant,
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but it would be centuries
before the details
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of their theory could be fully worked out.
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It would take the arrival of the space age.
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September, 1944, London was under siege.
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Brutal rockets were raining
down from the sky.
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Hitler's vengeance weapon
threw people into panic.
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Nothing had prepared them
for a supersonic missile
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that took just six minutes to travel
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from mainland Europe into
the heart of Britain.
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The technology behind these
missiles was highly advanced.
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It had been developed by a
brilliant young engineer
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called Wernher von Braun.
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Von Braun's rocket was called the V2.
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Designed to win the war for the Nazis,
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eventually it became the foundation
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of our journey to the planets.
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When Germany fell, American troops
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headed straight for the V2 factories.
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Before the dust had settled in Europe,
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Von Braun and his team of engineers
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found themselves working for
the United States Army.
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In the deserts of New Mexico,
the captured rocket parts
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were reassembled by U.S.
and German engineers.
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The modified V2s were soon flying
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way beyond the range of
conventional cameras.
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To record their progress,
the engineers fixed
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astronomical telescopes to
anti-aircraft gun mounts.
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The system was designed by Clyde Tombaugh,
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discoverer of Pluto, and
his films still survive.
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Before they left the
German rocket factories,
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the Americans destroyed
as much as they could
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to prevent Von Braun's secrets from falling
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into the hands of the advancing Red Army.
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But when they arrived, the
Soviets found just enough
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to take back to Moscow.
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The man given the task of
piecing together the rockets,
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was Sergei Pavlovich Korolev
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and Boris Chertok was his right hand man.
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While their brief was to develop rockets
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which could reach America, Korolev's eyes
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were fixed firmly on the planets.
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But in the early years, it was
the Americans who were ahead.
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By the end of the decade,
they were strapping
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film cameras to rockets and sending them
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high above the atmosphere.
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The cameras had to endure an
18 mile plummet back to Earth.
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Miraculously, some survived and
astronomers got their first
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glimps of the only planet
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they couldn't see with their telescopes.
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For the first time, scientists could see
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the arking horizon of the Earth.
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At last, they had a unique glimpse
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of the ball of rock and iron
that made up our world.
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How such a world could have
grown from a cloud of dust,
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seemed more baffling than ever.
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George Wetherill has dedicated his career
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to the question of planet formation.
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When he started his work, the science
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was dominated by one man.
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No great scientist ever devoted his life
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to understanding this problem,
it was sort of a hobby,
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something they did on the side
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and I think the first person
to really devote his life
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to this was a Russian scientist
named Viktor Safronov,
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who started working on these problems
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shortly after World War Two
and he tried to identify
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what all the scientific problems are,
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that you need to understand
and need to solve
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in order to understand the grand problem,
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the formation of the solar system.
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And to this day, his lists
of problems are essentially
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the same problems that
we're working on today.
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Viktor Safronov revisited
the 200 year old idea
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that the planets formed from
a cloud of gas and dust.
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He set about trying to break down
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this complex process into
several simple stages.
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The first stage is still
not fully understood.
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Remember, we're starting off
with very fine pieces of dust
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and the process of how you
get from something like that
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to something the size of a boulder,
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or even something the size of a mountain
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is actually not very well understood.
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Party line of the, of
what most people think
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actually happened was that
you had this disc of dust
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and the dust sort of
settled into the mid-plain
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00:18:18,489 --> 00:18:22,489
of the proto-planetary nebula, this disc.
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00:18:22,490 --> 00:18:25,209
And you got what's called a
gravitational instability
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that formed big clumps of
things the size of, maybe,
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a hundred meters in diameter.
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Safronov's second stage was less complex.
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It was called accretion.
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This was when the clumps
would gather together,
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gradually forming the planets
in our solar system.
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As they grew, a new force
became significant, gravity.
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A really amazing thing happens though,
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that Viktor Safronov discovered,
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and that is as these things start to grow,
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the bigger something gets,
the more it can eat.
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So end up with this run away situation
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where the bigger guys are
getting bigger still,
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faster than the little guys are,
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and it's sort of a race to
eat up all the little guys.
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And so you start off with
an uncountable number
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of objects that are the size of mountains
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and you end up with maybe a hundred
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in the inner part of the solar system.
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Objects about the size of the moon,
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or maybe going up to the size of Mars.
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Competing worlds hoovered
up the surrounding
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debris until there was simply no more left.
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In the inner solar system, where
there are now four planets,
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there were once, more than a hundred.
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How that army of worlds became
just four was still a puzzle,
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00:19:48,993 --> 00:19:51,152
but Viktor Safronov had a hunch
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that the process would leave those planets
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splattered with the scars of impact.
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Was this what we could see on the moon?
251
00:20:06,438 --> 00:20:09,893
Unknown to the West, Safronov
had taken a giant stride
252
00:20:09,894 --> 00:20:12,977
towards a theory of planet formation.
253
00:20:15,014 --> 00:20:17,132
Perhaps somewhere in the
solar system there might
254
00:20:17,133 --> 00:20:20,800
be a planet bearing
evidence for his theory.
255
00:20:25,053 --> 00:20:27,252
In 1957, the Americans announced
256
00:20:27,253 --> 00:20:31,253
that they were preparing
to enter the space age.
257
00:20:33,093 --> 00:20:34,412
They were about to launch
258
00:20:34,413 --> 00:20:37,663
the world's first artificial satellite.
259
00:20:40,013 --> 00:20:43,612
In the Soviet Union,
Korolev acted immediately.
260
00:20:43,613 --> 00:20:46,371
For Korolev it was the beginning
261
00:20:46,372 --> 00:20:50,242
of the race with Americas and he wanted
262
00:20:50,243 --> 00:20:54,076
to be first he wanted to
be ahead of Americas,
263
00:20:54,965 --> 00:20:59,198
like all of us and I think
he want to do this, maybe,
264
00:20:59,199 --> 00:21:02,032
hundred time more than any others.
265
00:21:03,939 --> 00:21:07,818
Then he call my father,
he told I want to launch
266
00:21:07,819 --> 00:21:10,179
this first satellite, lets do this
267
00:21:10,180 --> 00:21:13,013
before Americas as soon as we can.
268
00:21:17,800 --> 00:21:19,718
It would be a huge gamble, but finally,
269
00:21:19,719 --> 00:21:22,469
Khrushchev agrees to let him try.
270
00:21:30,672 --> 00:21:33,357
Now Korolev had to convince his engineers
271
00:21:33,358 --> 00:21:35,191
that they could do it.
272
00:22:38,777 --> 00:22:42,975
On October, the fourth, 1957,
while the Americans were
273
00:22:42,976 --> 00:22:47,095
still finalizing their
plans, Sputnik was launched.
274
00:23:55,627 --> 00:23:57,826
40 years on, Korolev's achievement
275
00:23:57,827 --> 00:24:00,327
is still celebrated in Russia.
276
00:24:03,672 --> 00:24:06,505
That evening, he was very proud.
277
00:24:07,588 --> 00:24:11,146
He realized that it is
the great achievement.
278
00:24:11,147 --> 00:24:14,786
And next day, he understood
that the reaction
279
00:24:14,787 --> 00:24:17,187
of the outside world is much stronger
280
00:24:17,188 --> 00:24:21,546
than it was in our country
and really there feeling was
281
00:24:21,547 --> 00:24:24,787
much stronger than even his feeling,
282
00:24:24,788 --> 00:24:27,455
especially in the United States.
283
00:24:32,784 --> 00:24:37,304
Korolev's rockets had
opened the door to space.
284
00:24:37,305 --> 00:24:39,943
We were getting closer to the planets.
285
00:24:42,423 --> 00:24:46,590
Bruce Murray is a veteran of the U.S.
space program.
286
00:24:47,484 --> 00:24:49,783
When his career started, the planets
287
00:24:49,784 --> 00:24:52,117
seemed a very long way away.
288
00:24:53,744 --> 00:24:55,704
He still remembers the first time
289
00:24:55,705 --> 00:24:58,462
that he saw Mars through a telescope.
290
00:24:58,463 --> 00:25:00,100
And it just blew me away.
291
00:25:00,101 --> 00:25:04,268
I was so taken with the fact
that here was a real object.
292
00:25:05,413 --> 00:25:08,203
It was three dimensional,
seemed to be three dimensional,
293
00:25:08,204 --> 00:25:12,723
it was colorful, and glowing and
it really drove home to me,
294
00:25:12,724 --> 00:25:14,475
there's another place out
there, a real place,
295
00:25:14,476 --> 00:25:18,559
not just something I studied
in school somewhere.
296
00:25:19,516 --> 00:25:22,191
As a young man, Bruce Murray
was taken under the wing
297
00:25:22,192 --> 00:25:24,991
of physicist, Bob Leighton,
who had developed a way
298
00:25:24,992 --> 00:25:28,409
to make time-lapsed films of the planets.
299
00:25:29,952 --> 00:25:31,752
The images were extraordinary because they
300
00:25:31,753 --> 00:25:33,671
could show the planet rotating.
301
00:25:33,672 --> 00:25:34,984
You could time lapse it,
you could take one frame,
302
00:25:34,985 --> 00:25:36,781
wait a minute, take another
frame and so forth,
303
00:25:36,782 --> 00:25:40,576
and make this time lapse and
it brought to everybody,
304
00:25:40,577 --> 00:25:44,136
the image of Mars that the
most dedicated astronomers
305
00:25:44,137 --> 00:25:46,893
only infer, 'cause they don't
see it that way either.
306
00:25:46,894 --> 00:25:49,612
They have to remember all those frames.
307
00:25:49,613 --> 00:25:50,893
So it was an extraordinary achievement.
308
00:25:50,894 --> 00:25:53,394
And he did it, it was for fun.
309
00:25:57,469 --> 00:26:01,636
Leighton's films brought
the planets to life.
310
00:26:10,094 --> 00:26:12,492
For the first time, astronomers
could see pictures
311
00:26:12,493 --> 00:26:15,160
of Jupiter moving through space.
312
00:26:20,293 --> 00:26:24,732
The outer planets, the ones
that are huge masses of gas,
313
00:26:24,733 --> 00:26:27,452
that, in the case of Jupiter or Saturn,
314
00:26:27,453 --> 00:26:30,252
you could actually see
some beautiful structure.
315
00:26:30,253 --> 00:26:32,933
The first thing that strikes one,
316
00:26:32,934 --> 00:26:35,456
as in the inner solar system is diversity,
317
00:26:35,457 --> 00:26:38,366
my Lord, everything is different.
318
00:26:38,367 --> 00:26:40,657
But Mars, the Earth's smaller cousin,
319
00:26:40,658 --> 00:26:42,969
was always the most tantalizing.
320
00:26:42,970 --> 00:26:47,287
Leighton could see mysterious
dark patches rotating
321
00:26:47,288 --> 00:26:49,448
with the planet, but what would
322
00:26:49,449 --> 00:26:52,888
a close encounter with the surface reveal?
323
00:27:02,169 --> 00:27:05,449
In 1963 the American
probe, Mariner Four set of
324
00:27:05,450 --> 00:27:09,969
to send back the first
pictures from another planet.
325
00:27:25,009 --> 00:27:26,368
And also to dust there are...
326
00:27:26,369 --> 00:27:28,289
Bob Leighton was responsible
327
00:27:28,290 --> 00:27:30,409
for bringing back the images.
And blue clouds.
328
00:27:30,410 --> 00:27:32,448
And clouds of the terminator
and clouds that...
329
00:27:32,449 --> 00:27:35,475
He asked Bruce Murray to join his team.
330
00:27:35,476 --> 00:27:37,563
I was dragged along, sucked along,
331
00:27:37,564 --> 00:27:40,730
however you wanna look at it,
into this wonderful experience
332
00:27:40,731 --> 00:27:43,051
of becoming the first experimenters
333
00:27:43,052 --> 00:27:46,830
to look at Mars through a close up camera.
334
00:27:46,831 --> 00:27:49,791
This is control center at JPL.
335
00:27:49,792 --> 00:27:53,959
The space craft is 134 point
217 million miles from Earth
336
00:27:55,188 --> 00:27:57,438
and 50,142 miles from Mars.
337
00:28:02,243 --> 00:28:05,427
After a journey of eight
months, Mariner Four
338
00:28:05,428 --> 00:28:08,948
was homing in on its first target.
339
00:28:08,949 --> 00:28:10,825
The first picture will cover an area
340
00:28:10,826 --> 00:28:12,584
of approximately 176 miles square
341
00:28:12,585 --> 00:28:15,262
on the sunlit lip of the planet.
342
00:28:15,263 --> 00:28:16,662
I wish I was as sure as he is.
343
00:28:16,663 --> 00:28:18,622
About 12 minutes from now,
344
00:28:18,623 --> 00:28:20,380
we should be able to
determine that the camera's,
345
00:28:20,381 --> 00:28:21,454
T.V. camera's shutter is operating
346
00:28:21,455 --> 00:28:23,384
and that the recorder is running.
347
00:28:23,385 --> 00:28:26,344
The anticipation of not
just the scientists,
348
00:28:26,345 --> 00:28:29,064
but the public and the news
media, it was incredible,
349
00:28:29,065 --> 00:28:33,232
because Mars was like to have
life and in the popular mind
350
00:28:34,285 --> 00:28:36,764
maybe it had Martians as far
as they were concerned.
351
00:28:36,765 --> 00:28:39,604
Mariner Four was a fly by.
352
00:28:39,605 --> 00:28:43,243
It would only get one
chance at the pictures.
353
00:28:43,244 --> 00:28:44,643
A.S. data reports the scan position
354
00:28:44,644 --> 00:28:47,365
for frame 605 as decimal
323 congratulations.
355
00:28:49,778 --> 00:28:52,278
323, 323 right on the money.
356
00:28:54,408 --> 00:28:56,825
Exactly where they wanted it.
357
00:28:59,849 --> 00:29:01,931
10,000 miles from the surface,
358
00:29:01,932 --> 00:29:05,008
Mariner 4's cameras whirled into life.
359
00:29:10,806 --> 00:29:14,973
These signals came back, if
you think of a one element,
360
00:29:16,406 --> 00:29:20,522
one picture element, one sample of light.
361
00:29:20,523 --> 00:29:23,241
The rate at which these
came in were from Mars,
362
00:29:23,242 --> 00:29:25,575
was one of these per second.
363
00:29:29,514 --> 00:29:31,953
Hey there we go.
There she goes.
364
00:29:31,954 --> 00:29:32,954
That's data.
365
00:29:33,954 --> 00:29:35,753
And so it took three weeks for our
366
00:29:35,754 --> 00:29:37,954
20 pictures to come back.
367
00:29:52,271 --> 00:29:55,975
Give me Bruce Murray's phone number.
368
00:29:55,976 --> 00:30:00,143
Where the devil are the Mars
pictures interpretators?
369
00:30:01,498 --> 00:30:05,665
Yeah, data's comin' in boy
what are you doing in bed?
370
00:30:07,357 --> 00:30:11,524
There it is. I think we got something.
371
00:30:17,875 --> 00:30:22,374
The planet was not what they had expected.
372
00:30:22,375 --> 00:30:26,453
There was no sign of life here.
No vegetation.
373
00:30:26,454 --> 00:30:30,621
Just picture after picture
of a dull, flat landscape.
374
00:30:35,414 --> 00:30:36,852
It wasn't until frame 12
375
00:30:36,853 --> 00:30:40,103
that the first features became visible.
376
00:30:42,213 --> 00:30:45,413
What we could see were these huge craters.
377
00:30:45,414 --> 00:30:49,414
300 kilometers, 200 mile
craters across on Mars.
378
00:30:52,333 --> 00:30:56,500
Impact craters, and that meant
that Mars was preserving
379
00:30:57,814 --> 00:31:01,612
a signature from these earliest times,
380
00:31:01,613 --> 00:31:04,613
three, four billion years ago and so we had
381
00:31:04,614 --> 00:31:07,573
a major conclusion, stunning to everybody,
382
00:31:07,574 --> 00:31:10,574
from these very few pictures we got.
383
00:31:15,494 --> 00:31:17,253
When the news filtered through
384
00:31:17,254 --> 00:31:18,972
to the Soviet Union, one man wasn't
385
00:31:18,973 --> 00:31:21,890
as surprised as his western rivals.
386
00:31:23,213 --> 00:31:27,380
Craters were exactly what
Viktor Safronov expected.
387
00:31:31,094 --> 00:31:34,973
Soon Safronov's idea's were
being discussed in the west.
388
00:31:34,974 --> 00:31:37,692
Where superior technology
allowed George Wetherell
389
00:31:37,693 --> 00:31:40,893
to take the accretion theory further.
390
00:31:40,894 --> 00:31:42,773
I called it the planetismal problem
391
00:31:42,774 --> 00:31:45,652
and it simply says you've
got a lot of objects,
392
00:31:45,653 --> 00:31:49,333
small planets moving
around the sun in orbits
393
00:31:49,334 --> 00:31:51,692
and what you'd like to understand is
394
00:31:51,693 --> 00:31:56,598
how they accumulate together
to form large planets.
395
00:31:56,599 --> 00:31:57,883
Wetherell's computers uncovered
396
00:31:57,884 --> 00:32:01,217
a terrifying period of planet formation.
397
00:32:02,365 --> 00:32:04,843
What you actually find,
if you do the problem
398
00:32:04,844 --> 00:32:07,843
with a computer, is that as they grow,
399
00:32:07,844 --> 00:32:10,677
they start to perturb one another,
400
00:32:11,564 --> 00:32:15,731
into orbits which cross the
orbit of another planet.
401
00:32:17,081 --> 00:32:20,360
The neat orbits of
Safronov's army of planets,
402
00:32:20,361 --> 00:32:24,042
soon became fatally disrupted
as they started tugging
403
00:32:24,043 --> 00:32:27,400
each other off course, these
different worlds sped
404
00:32:27,401 --> 00:32:31,201
towards each other, colliding
with shattering force.
405
00:32:39,317 --> 00:32:41,857
George realized that it was sort
406
00:32:41,858 --> 00:32:43,914
of like a wild frat party.
407
00:32:43,915 --> 00:32:45,593
All sort of hell brakes loose
408
00:32:45,594 --> 00:32:47,672
in the inner part of the solar system.
409
00:32:47,673 --> 00:32:50,594
Things are swung around,
half the stuff is either
410
00:32:50,595 --> 00:32:52,673
hits the sun, or gets
thrown out to Jupiter,
411
00:32:52,674 --> 00:32:54,834
which can then knock it
out of the solar system.
412
00:32:54,835 --> 00:32:57,988
It's a very violent happening party.
413
00:33:09,474 --> 00:33:12,268
If Wetherell is right,
than during this period,
414
00:33:12,269 --> 00:33:14,387
the inner solar system must have been
415
00:33:14,388 --> 00:33:16,721
strewn with planetary death.
416
00:33:18,928 --> 00:33:21,086
The four surviving planets
would have had to endure
417
00:33:21,087 --> 00:33:24,170
a final stage of intense bombardment.
418
00:33:33,287 --> 00:33:38,247
In 1973, George Wetherell got
the chance to test his work.
419
00:33:38,248 --> 00:33:41,415
Mariner 10 was on it's way to Mercury.
420
00:33:47,768 --> 00:33:49,887
78 million kilometers from Earth
421
00:33:49,888 --> 00:33:52,447
and far beyond the scope of even
422
00:33:52,448 --> 00:33:55,487
the most powerful telescopes, the surface
423
00:33:55,488 --> 00:33:58,568
of this planet was a total mystery.
424
00:33:58,569 --> 00:34:00,846
Just a few months before
the Mercury mission,
425
00:34:00,847 --> 00:34:03,487
I was at a meeting where, people discussed
426
00:34:03,488 --> 00:34:05,847
what we might find on Mercury in a sort of,
427
00:34:05,848 --> 00:34:09,007
get our minds active for
thinking about Mercury
428
00:34:09,008 --> 00:34:12,446
and a very distinguished
planetary astronomer,
429
00:34:12,447 --> 00:34:16,247
in answer to a question,
proclaimed that Mercury
430
00:34:16,248 --> 00:34:20,006
would have no craters on,
or very few craters.
431
00:34:20,007 --> 00:34:22,327
Curious thing is that, the craters
432
00:34:22,328 --> 00:34:26,495
on Mars were also a surprise
to most planetary astronomers.
433
00:34:27,568 --> 00:34:30,326
After a journey that took
in a fly by of Venus,
434
00:34:30,327 --> 00:34:34,327
By February, Mariner 10
was nearing it's target.
435
00:34:37,118 --> 00:34:39,760
Subsequently, though, however,
I had the opportunity
436
00:34:39,761 --> 00:34:43,193
to be invited to JPL and
sit in a little room
437
00:34:43,194 --> 00:34:46,745
up above mission control
and see the pictures
438
00:34:46,746 --> 00:34:48,996
of Mercury as they came in.
439
00:34:51,471 --> 00:34:53,053
First pictures of Mercury started coming
440
00:34:53,054 --> 00:34:54,932
and at first it was just
sort of a fuzzy ball
441
00:34:54,933 --> 00:34:57,614
and you could sort of imagine
these small craters,
442
00:34:57,615 --> 00:34:59,693
but after awhile, it got closer and closer.
443
00:34:59,694 --> 00:35:02,734
Pretty soon it started to
look just like the moon.
444
00:35:02,735 --> 00:35:04,492
Mercury turned out to be
445
00:35:04,493 --> 00:35:06,893
the most heavily cratered
planet in the solar system.
446
00:35:06,894 --> 00:35:09,854
One impact was so great,
it left shock waves,
447
00:35:09,855 --> 00:35:13,688
set in stone, on the other
side of the planet.
448
00:35:14,613 --> 00:35:18,780
It was proof of the final stage
of the accretion theory.
449
00:35:20,694 --> 00:35:23,373
And I was just thrilled by this.
450
00:35:23,374 --> 00:35:27,092
I knew they were there,
but actually seeing them,
451
00:35:27,093 --> 00:35:31,173
that I'd been thinking
about all these years,
452
00:35:31,174 --> 00:35:33,574
now here they are for me to look at,
453
00:35:33,575 --> 00:35:36,292
made me very excited and
I've also excited all these
454
00:35:36,293 --> 00:35:38,172
military men around, they kept saying,
455
00:35:38,173 --> 00:35:42,340
isn't that beautiful, it's
just like a '52 drop in 'nam.
456
00:35:55,191 --> 00:35:58,590
Here then, are the inner planets.
457
00:35:58,591 --> 00:36:02,310
The survivors of a life or death struggle.
458
00:36:02,311 --> 00:36:04,394
Mercury, Venus, and Mars.
459
00:36:06,951 --> 00:36:10,368
Each bearing the scars of their creation.
460
00:36:12,797 --> 00:36:14,630
But what of the Earth?
461
00:36:17,672 --> 00:36:21,352
Surely our planet could not
have survived unscathed.
462
00:36:41,755 --> 00:36:43,951
Out in Arizona, Hal
Levison, reveals evidence
463
00:36:43,952 --> 00:36:48,271
of the violence that once
rained down from space.
464
00:37:10,985 --> 00:37:15,152
This hole in the ground was
made in a matter of seconds.
465
00:37:17,544 --> 00:37:20,977
Despite being a very awesome sight,
466
00:37:20,978 --> 00:37:24,677
something that tells us that
the solar system is still
467
00:37:24,678 --> 00:37:27,997
active and things are still
running into each other.
468
00:37:27,998 --> 00:37:32,165
It's a relatively small,
insignificant hole in the ground.
469
00:37:38,878 --> 00:37:40,957
Around 50,000 years ago,
470
00:37:40,958 --> 00:37:43,478
a 50 meter fragment of a world blown apart
471
00:37:43,479 --> 00:37:47,646
billions of years earlier,
careered into our planet.
472
00:37:49,519 --> 00:37:53,686
Here is evidence on Earth of
the final stages of accretion.
473
00:37:57,238 --> 00:38:00,957
But what of the world's that
dwarf the inner planets?
474
00:38:00,958 --> 00:38:04,278
How does the accretion theory
account for the gassy giants
475
00:38:04,279 --> 00:38:07,438
in the distant regions of our solar system?
476
00:38:12,159 --> 00:38:13,758
We have very different planets.
477
00:38:13,759 --> 00:38:15,799
Types of planets as we
get farther from the sun
478
00:38:15,800 --> 00:38:17,751
and that's because as you
get farther from the sun,
479
00:38:17,752 --> 00:38:20,708
the temperatures dropped
and particularly at about
480
00:38:20,709 --> 00:38:23,708
four times more distant from
the sun than the Earth is,
481
00:38:23,709 --> 00:38:26,303
we hit a point where
water would condense out
482
00:38:26,304 --> 00:38:27,887
and become a solid.
483
00:38:28,983 --> 00:38:30,904
With water turning to ice,
484
00:38:30,905 --> 00:38:33,063
the amount of material available to form
485
00:38:33,064 --> 00:38:36,183
the outer planets was far greater.
486
00:38:36,184 --> 00:38:39,063
Jupiter and Saturn grew so
large, they started sucking
487
00:38:39,064 --> 00:38:43,343
in the primordial gases from
the original dust cloud,
488
00:38:43,344 --> 00:38:47,511
swelling them to hundreds of
times the mass of the Earth.
489
00:38:49,614 --> 00:38:52,140
This region was populated
with many more planets
490
00:38:52,141 --> 00:38:56,308
than exist today, their
orbits were also disrupted.
491
00:38:57,501 --> 00:39:01,340
We can find no traces of impacts
in their gassy atmospheres,
492
00:39:01,341 --> 00:39:04,181
but evidence can be seen in their rotation.
493
00:39:04,182 --> 00:39:06,741
It's believed that a world
the size of the Earth,
494
00:39:06,742 --> 00:39:08,192
collided with Uranus.
495
00:39:12,993 --> 00:39:15,472
As a result, today Uranus still rolls
496
00:39:15,473 --> 00:39:17,890
around the sun, on it's back.
497
00:39:32,413 --> 00:39:36,580
When did these planet building
impacts come to an end?
498
00:39:38,132 --> 00:39:40,772
I've found a lot of comets,
I've been involved now
499
00:39:40,773 --> 00:39:42,771
in the discovery of 21 of them.
500
00:39:42,772 --> 00:39:46,932
There is nothing like the night
we found Shoemaker Levy 9.
501
00:39:46,933 --> 00:39:49,931
We had no idea how important
that discovery was going to be.
502
00:39:49,932 --> 00:39:53,172
It made page 23 in the London Times.
503
00:39:53,173 --> 00:39:55,064
That Carolyn and Gene Shoemaker
504
00:39:55,065 --> 00:39:57,732
and I had discovered this comet.
505
00:39:59,563 --> 00:40:01,883
Interest increase several months later
506
00:40:01,884 --> 00:40:03,842
when it was announced that Shoemaker Levy 9
507
00:40:03,843 --> 00:40:07,799
was on a collision course with Jupiter.
508
00:40:07,800 --> 00:40:11,198
This was not page 23 of the London Times,
509
00:40:11,199 --> 00:40:12,878
this was now page one.
510
00:40:12,879 --> 00:40:14,719
This is a very different story.
511
00:40:14,720 --> 00:40:18,887
Shoemaker Levy 9 was gonna
show us what it's all about.
512
00:40:21,521 --> 00:40:24,474
In all of civilization, since Galileo
513
00:40:24,475 --> 00:40:26,844
first looked through a telescope in 1609,
514
00:40:26,845 --> 00:40:30,284
and since he first looked
at Jupiter in 1610,
515
00:40:30,285 --> 00:40:32,404
this is the first time that we will
516
00:40:32,405 --> 00:40:36,164
ever have seen a comet strike a planet.
517
00:40:36,165 --> 00:40:38,725
July the 16th, 1994.
518
00:40:38,726 --> 00:40:41,803
Impact day and every available telescope
519
00:40:41,804 --> 00:40:44,203
is trained on Jupiter.
520
00:40:44,204 --> 00:40:45,881
Look!
521
00:40:45,882 --> 00:40:48,549
Oh my God! Look at that! Look!
522
00:41:02,881 --> 00:41:04,680
This is how the solar system was built.
523
00:41:04,681 --> 00:41:07,159
Comets hitting planets, comets
first hitting each other.
524
00:41:07,160 --> 00:41:09,720
Very slowly and it's kind of an embrace
525
00:41:09,721 --> 00:41:13,560
rather than a collision and
then these objects get bigger,
526
00:41:13,561 --> 00:41:15,799
their gravity gets bigger,
the collisions get faster
527
00:41:15,800 --> 00:41:18,961
and the speed gets higher
and it gets more violent
528
00:41:18,962 --> 00:41:22,439
as the solar system reaches
its teenage years it's become
529
00:41:22,440 --> 00:41:26,607
a little bit dysfunctional and
finally, when does it end?
530
00:41:28,282 --> 00:41:29,920
Well, what Shoemake Levy 9 taught us
531
00:41:29,921 --> 00:41:32,839
was that it hasn't happened yet.
532
00:41:32,840 --> 00:41:36,921
Right then, in the summer
of 1994, around Jupiter,
533
00:41:36,922 --> 00:41:40,681
there's a big yellow
police fence that says,
534
00:41:40,682 --> 00:41:45,036
danger, keep out, solar
system under construction.
535
00:41:45,037 --> 00:41:48,230
It's still happening.
Jupiter grew a little bit
536
00:41:48,231 --> 00:41:51,350
during the week of July 16th 1994.
537
00:41:51,351 --> 00:41:53,471
Water was dumped on Jupiter.
538
00:41:53,472 --> 00:41:56,310
It had more carbon sulfate
now than it had then.
539
00:41:56,311 --> 00:41:59,190
It was as if nature had said, OK guys,
540
00:41:59,191 --> 00:42:01,858
I'm gonna show you how it works.
541
00:42:03,592 --> 00:42:05,388
And all you have to do is watch it.
542
00:42:35,527 --> 00:42:37,647
These are the gas giants.
543
00:42:37,648 --> 00:42:39,527
Jupiter and Saturn mark the current limits
544
00:42:39,528 --> 00:42:42,278
of the planet builder's theories.
545
00:42:47,097 --> 00:42:51,097
Far beyond these vast
worlds lie the ice giants,
546
00:42:52,044 --> 00:42:53,627
Uranus and Neptune.
547
00:42:57,004 --> 00:43:01,171
But out here the accretion
theory runs into trouble.
548
00:43:03,804 --> 00:43:05,724
The formation of Uranus and
Neptune are the greatest
549
00:43:05,725 --> 00:43:09,324
mysteries in the formation
of the solar system
550
00:43:09,325 --> 00:43:11,948
because everything goes more
slowly at greater distances
551
00:43:11,949 --> 00:43:15,216
from the sun so all these
processes slow down.
552
00:43:15,217 --> 00:43:17,615
When we try to run the
same computer programs
553
00:43:17,616 --> 00:43:21,051
out there that we did in the
terrestrial planet zone,
554
00:43:21,052 --> 00:43:23,469
we don't get planets forming.
555
00:43:24,431 --> 00:43:26,667
No matter what we do, we can't form
556
00:43:26,668 --> 00:43:30,747
Uranus and Neptune using
those kind of models.
557
00:43:30,748 --> 00:43:33,707
No matter how hard I try, I
can't make Uranus and Neptune
558
00:43:33,708 --> 00:43:37,926
go away, they're there and
our models can't make them.
559
00:43:37,927 --> 00:43:40,765
So we do indeed have a
lot of, a long way to go
560
00:43:40,766 --> 00:43:43,924
before we really figure all this out.
561
00:43:43,925 --> 00:43:47,330
How these worlds formed
so quickly is a puzzle.
562
00:43:47,331 --> 00:43:50,482
Scientists don't know enough
about early conditions
563
00:43:50,483 --> 00:43:52,316
this far from the sun.
564
00:43:53,323 --> 00:43:55,041
What kinds of worlds went into
565
00:43:55,042 --> 00:43:58,042
the formation of Uranus and Neptune.
566
00:43:59,002 --> 00:44:02,720
In 1992, two astronomers
were surveying the space
567
00:44:02,721 --> 00:44:06,888
beyond Neptune and they found
a substantial chunk of ice.
568
00:44:08,163 --> 00:44:10,603
Since then, they've found many more.
569
00:44:10,604 --> 00:44:13,480
Called the Kuiper belt, it's now thought
570
00:44:13,481 --> 00:44:15,640
to contain the building blocks
571
00:44:15,641 --> 00:44:18,141
of ice giants that never were.
572
00:44:19,002 --> 00:44:23,169
The Kuiper belt is a region
where the small ice mountains
573
00:44:24,162 --> 00:44:26,378
that we were talking about
actually started accreting
574
00:44:26,379 --> 00:44:29,257
and building into larger things.
575
00:44:29,258 --> 00:44:31,458
That's really, to me, the
region we need to look at.
576
00:44:31,459 --> 00:44:32,613
Because what happened there is
577
00:44:32,614 --> 00:44:36,372
planet formation started
there and it was frozen in
578
00:44:36,373 --> 00:44:39,928
in some intermediate state and
trying to understand that,
579
00:44:39,929 --> 00:44:42,648
will let us know, in more detail,
580
00:44:42,649 --> 00:44:45,408
how the accretion process started,
581
00:44:45,409 --> 00:44:47,946
but what shut it off is also
going to be interesting.
582
00:44:47,947 --> 00:44:50,746
Tell us something about
the process as well.
583
00:44:50,747 --> 00:44:52,506
So to me, the future really lies
584
00:44:52,507 --> 00:44:55,426
in the outer part of the solar system.
585
00:44:55,427 --> 00:44:57,285
But there's a planet that lies
586
00:44:57,286 --> 00:45:00,005
at the inner edge of the Kuiper belt.
587
00:45:00,006 --> 00:45:02,844
70 years after it's discovery,
the strange tiny world
588
00:45:02,845 --> 00:45:05,928
of Pluto may at last be making sense.
589
00:45:08,047 --> 00:45:10,926
Pluto was discovered in 1930, right.
590
00:45:10,927 --> 00:45:13,886
And it was the odd ball
of the solar system.
591
00:45:13,887 --> 00:45:16,806
Most of the planets are in nice
circular orbits, not Pluto.
592
00:45:16,807 --> 00:45:19,805
Most of the planets sit in the plain
593
00:45:19,806 --> 00:45:23,086
that represents the
accretion disc, not Pluto.
594
00:45:23,087 --> 00:45:27,646
And it was just an odd ball,
it was small, and icy,
595
00:45:27,647 --> 00:45:29,726
and it had no similarity to anything else
596
00:45:29,727 --> 00:45:32,485
that we really knew about.
597
00:45:32,486 --> 00:45:34,969
Could this small icy world
598
00:45:34,970 --> 00:45:36,926
be one of the survivors of accretion.
599
00:45:36,927 --> 00:45:39,406
A world that somehow
escaped being swallowed up
600
00:45:39,407 --> 00:45:41,846
by the growing Neptune, or being hurled
601
00:45:41,847 --> 00:45:43,847
out of the solar system.
602
00:45:44,726 --> 00:45:46,566
Could Pluto be the missing link
603
00:45:46,567 --> 00:45:49,766
of the formation of the ice giants.
604
00:45:49,767 --> 00:45:52,205
Turns out, Pluto was just
the largest known member
605
00:45:52,206 --> 00:45:56,605
of this population, so
it went from being this
606
00:45:56,606 --> 00:46:00,765
lonely, remote odd ball,
to being essentially,
607
00:46:00,766 --> 00:46:03,516
the grandfather of a population.
608
00:46:03,517 --> 00:46:06,177
And we're talking about, the Kuiper belt,
609
00:46:06,178 --> 00:46:07,492
probably has more objects in it than any
610
00:46:07,493 --> 00:46:09,691
other region in the solar system.
611
00:46:09,692 --> 00:46:12,091
So it's the most populous
region in the solar system,
612
00:46:12,092 --> 00:46:15,531
yet we didn't know about 10 years ago.
613
00:46:15,532 --> 00:46:17,725
In the 40 years since Metchtar broke free
614
00:46:17,726 --> 00:46:19,844
from the Earth's gravity,
615
00:46:19,845 --> 00:46:21,905
we've sent probes to all the planets.
616
00:46:21,906 --> 00:46:25,025
We've sampled the corrosive clouds of Venus
617
00:46:25,026 --> 00:46:28,943
and recorded planet wide
storms on its surface.
618
00:46:30,860 --> 00:46:32,698
We've viewed dust storms on Mars
619
00:46:32,699 --> 00:46:36,038
and seen canyons that
could swallow countries.
620
00:46:36,039 --> 00:46:39,248
We've mapped the icy moons of Jupiter
621
00:46:39,249 --> 00:46:41,999
and plunged into it's atmosphere.
622
00:46:43,495 --> 00:46:46,328
We've skimmed the rings of Saturn.
623
00:46:48,415 --> 00:46:50,910
We've seen active geysers
on the most distant
624
00:46:50,911 --> 00:46:54,078
and freezing moon in the solar system.
625
00:46:56,353 --> 00:46:58,472
But just as the first stage of our journey
626
00:46:58,473 --> 00:47:00,672
to the planets draws to a close,
627
00:47:00,673 --> 00:47:03,173
further worlds are opening up.
628
00:47:06,632 --> 00:47:09,908
In 1992, Clyde Tombaugh got
what he'd been waiting
629
00:47:09,909 --> 00:47:13,326
for from NASA, permission to visit Pluto.
630
00:47:14,688 --> 00:47:18,345
Clyde was melted, he melted
when he got that letter.
631
00:47:18,346 --> 00:47:20,666
He felt that all his life's effort,
632
00:47:20,667 --> 00:47:23,865
all of his life's work, with Pluto,
633
00:47:23,866 --> 00:47:27,185
with his work at White Sands
was coming to a head.
634
00:47:27,186 --> 00:47:30,785
He felt that that letter was really a sign
635
00:47:30,786 --> 00:47:33,225
that NASA, through there mission to Pluto,
636
00:47:33,226 --> 00:47:37,393
was finally acknowledging him
as the man that he really was.
637
00:47:40,106 --> 00:47:42,439
Clyde Tombaugh died in 1997.
638
00:47:43,547 --> 00:47:47,714
A probe, heading towards
Pluto will launch in 2006.
639
00:47:49,944 --> 00:47:52,261
After analyzing the planets composition,
640
00:47:52,262 --> 00:47:55,342
it will head out towards the Kuiper Belt,
641
00:47:55,343 --> 00:47:57,338
piecing together the final clues
642
00:47:57,339 --> 00:48:00,938
of how our solar system was formed.
643
00:48:00,939 --> 00:48:02,539
Whatever the craft finds,
644
00:48:02,540 --> 00:48:05,957
Pluto's importance is now unquestionable.
645
00:48:08,060 --> 00:48:10,257
It will be a manned mission
646
00:48:10,258 --> 00:48:12,298
to Pluto in a very special sense.
647
00:48:12,299 --> 00:48:14,138
It's not going to have
a real living person,
648
00:48:14,139 --> 00:48:17,278
but you can bet that's it's
gonna have Clyde's spirit
649
00:48:17,279 --> 00:48:19,917
on board on its way to Pluto to see,
650
00:48:19,918 --> 00:48:23,120
what kind of a planet that
little guy really is.
53086
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