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Lift off of Messenger on Nasa's
mission to Mercury.
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# They'll say
no-one can see us
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00:00:16,240 --> 00:00:23,960
# That we're estranged
and all alone
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00:00:23,960 --> 00:00:31,080
# They believe
nothing can reach us
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00:00:31,080 --> 00:00:38,280
# And pull us out of
the boundless gloom
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00:00:38,280 --> 00:00:44,920
# They're wrong
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# They're wrong. #
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Beyond the inner solar system...
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..past the asteroid belt...
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..lies Jupiter.
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The largest of the planets
is a giant swirling ball of gas...
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..its marbled appearance generated
by violent winds
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00:01:29,560 --> 00:01:31,800
that rage through its clouds.
14
00:01:41,560 --> 00:01:45,560
Jupiter is a world as strange
as it is remote.
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00:01:51,320 --> 00:01:54,640
If you fly upwards, only about
100km or so,
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you reach the edge of our atmosphere
and the blackness of space.
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It's really not that far.
18
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But once you're in space,
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00:02:01,880 --> 00:02:05,600
the distance scales are sort of
incomprehensible.
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00:02:05,600 --> 00:02:09,560
I mean, Venus, the closest planet,
is over 40 million kilometres away.
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00:02:09,560 --> 00:02:12,880
Jupiter around 650 million
kilometres.
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00:02:12,880 --> 00:02:17,080
It takes our fastest spacecraft
years to get there.
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00:02:17,080 --> 00:02:21,560
So, the idea that those planets
could have any influence on us
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00:02:21,560 --> 00:02:23,800
here on Earth seems fanciful.
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And, indeed, if you're talking about
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your chances of meeting a handsome
stranger
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or your life plans requiring a
moderate reconfiguration
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about a week on Wednesday,
then you would be right.
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00:02:35,800 --> 00:02:40,720
However, if you ask more profound
questions, deeper questions like,
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"Why is the Earth the way that it
is?
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00:02:43,120 --> 00:02:45,000
"Why is there life on Earth?
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"Why do we exist at all?"
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00:02:47,360 --> 00:02:50,840
then it turns out that the planets,
and Jupiter in particular,
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have had a profound effect.
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THUNDER
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00:03:09,640 --> 00:03:13,680
Early in its life, the young
Jupiter went on the rampage.
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00:03:21,680 --> 00:03:25,160
The giant planet embarked
on a voyage of destruction
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00:03:25,160 --> 00:03:26,960
across the solar system...
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00:03:28,160 --> 00:03:31,440
..that transformed the destiny
of the planets,
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00:03:31,440 --> 00:03:33,720
and the course of life on Earth.
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00:03:44,800 --> 00:03:48,120
Jupiter is the godfather
of the planets.
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00:03:50,280 --> 00:03:54,760
Understand it and you understand
how the solar system came to be.
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00:04:16,720 --> 00:04:21,120
On Earth, we can see glimpses
of Jupiter's power...
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..in the scars it's left...
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..on the face of the planet.
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This is the famous Barringer
Meteor Crater in Arizona.
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It is about a kilometre across,
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170 metres from the rim to the
crater floor
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and it was created about 50,000
years ago
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when a meteorite, 50 metres across,
entered the Earth's atmosphere
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travelling at about 13km per
second.
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00:05:00,240 --> 00:05:02,840
That means it would have taken
around, what, seven seconds
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00:05:02,840 --> 00:05:05,920
to go from the top of the atmosphere
to the ground
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and it hit with such force that the
energy released
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was equivalent to ten megatons of
TNT.
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00:05:12,600 --> 00:05:15,320
And that is a very large
nuclear bomb.
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00:05:20,200 --> 00:05:22,360
The meteorite that hit the Earth
here
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is thought to have come from the
asteroid belt...
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..the ring of rocky debris
that orbits at the edge
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00:05:30,880 --> 00:05:32,800
of the inner solar system.
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00:05:36,160 --> 00:05:38,840
And it was deflected from its orbit
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most likely by the gravitational
influence of Jupiter.
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00:05:51,520 --> 00:05:55,280
Jupiter is a completely different
class of planet to the Earth.
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A gas giant.
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A swirling ball of hydrogen
and helium so large
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you could fit 1,300 Earths inside.
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Jupiter can exert such a powerful
influence on the asteroids
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because it's so massive.
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It's about two-and-a-half times
the mass of all the other planets,
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00:06:22,680 --> 00:06:26,360
moons and asteroids in the solar
system combined.
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And, therefore, it has a strong
gravitational pull.
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00:06:30,400 --> 00:06:33,480
And this means that Jupiter
exerts an influence
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across the entire solar system
that's second only to the sun.
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And that influenced us far
more than create the odd crater.
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It can change the history
of worlds.
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00:06:56,720 --> 00:07:00,960
To understand how Jupiter rose
to such dominance,
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you have to go back to a time before
the solar system even existed.
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Nearly five billion years ago,
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a distant exploding star sent
a shock wave across the galaxy...
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..causing the cloud of gas and dust
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that would become our solar system
to collapse...
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..as the sun began to form.
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00:07:52,680 --> 00:07:56,880
But further out, something
else was growing.
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00:08:03,240 --> 00:08:04,880
After 50 million years...
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..the sun's nuclear furnace ignited.
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The light of its first dawn...
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..revealing Jupiter...
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..the solar system's first world.
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A planet born so early, it swept
up most of the material
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00:08:38,640 --> 00:08:41,640
left over from the formation of the
sun.
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00:08:48,200 --> 00:08:51,560
Because of its dominance, Jupiter
had a profound effect
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on the newly forming solar system
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and paved the way for our living
world to form.
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00:09:01,520 --> 00:09:04,080
This is a model of our solar system.
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So, here's the sun, and then we have
the four inner rocky planets,
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Mercury, Venus, Earth and Mars.
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00:09:13,600 --> 00:09:16,360
Then comes the asteroid belt,
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the ring of millions of smaller
pieces of rock
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orbiting around the sun.
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And then the gas giants.
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Jupiter, Saturn, Uranus and Neptune.
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Now, this has a pleasing regular
structure about it.
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All the rocky planets close to the
star
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and the gas giants further out.
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And we thought that this must be the
natural order of things,
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the way that solar systems
have to form,
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until we started to detect planets
around distant stars
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and then we found that this
arrangement is not typical at all.
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Our sun is just one of around
300 billion stars in our galaxy...
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..and almost every one of those
stars
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is home to its own system of
planets.
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00:10:17,200 --> 00:10:22,560
In most other systems, the region
where our planet orbits is empty.
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Instead, closer to the star, we see
super-Earths,
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vast rocky planets
many times bigger than our own.
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But, crucially, these worlds are
thought
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to have thick toxic
atmospheres,
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making them completely inhospitable
to life.
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And that raises a very interesting
question.
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Why, then, is our solar system
the way that it is?
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00:11:08,280 --> 00:11:09,760
To answer that question,
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we've sent spacecraft to every one
of the planets...
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00:11:15,600 --> 00:11:18,040
..and they've uncovered strange
anomalies
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that reveal our solar system's past.
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00:11:23,720 --> 00:11:27,680
Our missions to Venus found
that it once had far more water
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than you'd expect for a planet
so close to the sun...
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..just as Earth does today.
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00:11:39,760 --> 00:11:42,000
The spacecraft we've sent to Mars
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touched down on a world that is
curiously just half the size
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00:11:46,200 --> 00:11:49,440
of her sister planets Earth and
Venus.
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And in the asteroid belt,
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we've uncovered a graveyard
of failed worlds...
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..their growth mysteriously cut
short.
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To cause all these anomalies,
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00:12:16,720 --> 00:12:20,840
it's thought that something
catastrophic must have happened
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00:12:20,840 --> 00:12:23,240
very early in the solar system's
history.
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00:12:26,400 --> 00:12:30,120
All the evidence suggests
that around 4.5 billion years ago,
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Jupiter's orbit began to change,
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00:12:32,280 --> 00:12:35,080
triggering a period of unprecedented
violence
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00:12:35,080 --> 00:12:39,320
which completely transformed the
face of the young solar system.
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00:12:39,320 --> 00:12:41,800
And we know this because
the marauding planet
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left a trail of destruction in its
wake.
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Early in its life, Jupiter began
to move inwards towards the sun...
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..and the effects of that journey
can be seen to this day.
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00:13:14,440 --> 00:13:18,120
In between the orbits of Mars
and Jupiter...
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..lies the asteroid belt...
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..a desolate wasteland of debris
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left over from the beginning
of the solar system.
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00:13:37,640 --> 00:13:41,840
Rocky bodies too small to be planets
in their own right.
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In science fiction films, the
asteroid belt is often depicted
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as an un-navigable
mass of tumbling rubble.
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00:14:04,800 --> 00:14:06,200
But it's not like that at all.
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So much so, in fact, that modern
spacecraft engineers
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can fly a spacecraft through without
making any course corrections.
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00:14:13,720 --> 00:14:16,800
The reason for that is there's not
much mass in the asteroid belt.
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00:14:16,800 --> 00:14:21,040
A sum total of all of them is only
about 4% the mass of the moon
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and they're spread out in a huge
sort of ring,
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out beyond the orbit of Mars.
So, it's a vast amount of space.
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That means that the average distance
between any two large asteroids
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is about eight times the distance
between the Earth and the moon.
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So, I could stand on one of those
large asteroids
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and look out into space
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and my nearest neighbour would just
be a dim star in the dark.
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But scattered amongst the rubble
are objects
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that are far more than mere rocks.
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Five, four, three,
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two, main engine start, one,
zero and lift off
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of the Delta II Rocket.
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00:15:07,000 --> 00:15:09,440
In 2007, Nasa's Dawn mission
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was sent to explore the two largest
objects in the asteroid belt.
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After a year in orbit around
the giant asteroid Vesta...
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..in March 2015...
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..Dawn made its final approach
on a body so large
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it makes up almost a third of the
mass of the entire asteroid belt...
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..Ceres.
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On arrival, the first images Dawn
sent back to Earth
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contained something entirely
unexpected...
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..mysterious bright patches in one
of Ceres' largest craters.
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Spectral analysis of the images
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showed that the patches were, in
fact,
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the salty residue left
behind by liquid water...
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..suggesting there must be large
amounts of ice
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just beneath the crust.
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00:17:17,720 --> 00:17:22,800
Dawn went on to discover over 300
bright spots all over the surface.
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00:17:27,920 --> 00:17:30,640
And this means that beneath
this thin crust,
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Ceres has a thick ice rich mantle
surrounding its rocky core...
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00:17:40,000 --> 00:17:44,680
..evidence that the dwarf planet
is made up of multiple layers.
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00:17:58,000 --> 00:18:02,240
The interior of Ceres is like
nothing else in the asteroid belt.
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The differentiation, that separation
into layers, observed by Dawn
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is more characteristic of a planet
than an asteroid.
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00:18:10,400 --> 00:18:14,840
So, 4.5 billion years ago, Ceres
was well on its way
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00:18:14,840 --> 00:18:16,800
to becoming a fully-fledged world.
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It's thought that's in its infancy
Ceres was very different.
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The water that now lies frozen
within its interior was once liquid.
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Protected beneath a thin
layer of ice...
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00:18:51,840 --> 00:18:55,680
..Ceres was once covered
by a deep saltwater ocean.
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Before Ceres had reached
its full potential,
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00:19:16,320 --> 00:19:18,680
a great disturbance sent shock
waves through
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00:19:18,680 --> 00:19:21,040
what would one day become the
asteroid belt
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00:19:21,040 --> 00:19:23,080
and cut its development short.
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00:19:35,480 --> 00:19:38,160
As Jupiter circled the young sun,
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00:19:38,160 --> 00:19:41,400
it started to clear a path
through the gas and dust
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00:19:41,400 --> 00:19:43,200
that shrouded the early
solar system...
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00:19:49,920 --> 00:19:53,840
..but that process caused it to do
something alarming.
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Gravitational interactions with the
gas made the giant planets
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00:20:00,080 --> 00:20:02,240
spiral inwards towards the sun...
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00:20:05,600 --> 00:20:07,880
..ploughing straight through the
region of space
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00:20:07,880 --> 00:20:09,960
that would become the asteroid
belt...
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00:20:12,640 --> 00:20:14,920
..scattering the material
from which Ceres
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00:20:14,920 --> 00:20:16,520
would otherwise have grown.
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00:20:23,320 --> 00:20:26,080
Computer simulations of the early
solar system
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suggest that the asteroid belt once
contained enough material
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00:20:29,560 --> 00:20:32,440
to build a planet the size of the
Earth.
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00:20:32,440 --> 00:20:35,440
And perhaps that was Ceres's
destiny.
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00:20:35,440 --> 00:20:38,480
But when Jupiter passed through,
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00:20:38,480 --> 00:20:42,480
it scattered 99.9% of the material
away,
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00:20:42,480 --> 00:20:44,560
and Ceres's fate was sealed.
217
00:20:51,280 --> 00:20:55,120
Within 100 million years, Ceres's
ocean froze
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00:20:55,120 --> 00:20:57,240
and was buried beneath its crust.
219
00:21:01,640 --> 00:21:04,400
The young planet's development
cut short
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00:21:04,400 --> 00:21:06,880
before it could fulfil its promise.
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00:21:19,880 --> 00:21:23,560
But Jupiter's reign of terror was
far from over.
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00:21:30,440 --> 00:21:32,480
It would continue its journey
inwards
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00:21:32,480 --> 00:21:34,920
towards the place our planet
was beginning to form...
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00:21:38,160 --> 00:21:41,240
..threatening the very existence of
Earth.
225
00:21:46,480 --> 00:21:50,600
Jupiter had such an overwhelming
effect on the young solar system
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00:21:50,600 --> 00:21:53,120
because of its powerful
gravitational field...
227
00:22:12,680 --> 00:22:16,160
..the effects of which we can
still witness today.
228
00:23:10,640 --> 00:23:13,520
Jupiter exerts its influence
across the solar system
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00:23:13,520 --> 00:23:15,480
through its gravitational field...
230
00:23:24,240 --> 00:23:27,680
..which is by far the most powerful
of all the planets,
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00:23:27,680 --> 00:23:30,520
because Jupiter is the most massive
of all the planets.
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00:23:30,520 --> 00:23:34,560
It's about 320 times the mass
of the Earth.
233
00:23:34,560 --> 00:23:37,240
That's why it was so destructive
in the past.
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00:23:37,240 --> 00:23:40,880
And we see the power of
that gravitational field today
235
00:23:40,880 --> 00:23:45,960
in its influence on the closest
of Jupiter's largest moons, Io.
236
00:23:59,640 --> 00:24:02,920
Io is the most volcanic
world in the solar system.
237
00:24:08,120 --> 00:24:11,920
Its surface covered with hundreds
of active volcanoes...
238
00:24:17,000 --> 00:24:19,000
..and lakes of molten lava.
239
00:24:25,560 --> 00:24:28,800
The largest, known as Loki Patera,
240
00:24:28,800 --> 00:24:31,960
is more than 200km in diameter.
241
00:24:41,200 --> 00:24:44,880
A million times the area
of any lava lake on Earth.
242
00:24:46,680 --> 00:24:50,120
Its surface tormented by waves
of molten rock.
243
00:25:02,920 --> 00:25:04,960
Io is a vision of hell...
244
00:25:10,720 --> 00:25:13,920
..created by the moon's proximity
to Jupiter.
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00:25:33,080 --> 00:25:37,440
Volcanism here on Earth
is powered by the internal heat
246
00:25:37,440 --> 00:25:39,280
down below the surface.
247
00:25:39,280 --> 00:25:41,160
Now, much of that is residual heat
248
00:25:41,160 --> 00:25:43,360
left over from the Earth's
formation
249
00:25:43,360 --> 00:25:47,040
four-and-a-half billion years ago,
about half of it, and the other half
250
00:25:47,040 --> 00:25:51,680
is down to radioactive decay of
elements around the Earth's core.
251
00:25:51,680 --> 00:25:54,120
Now, on Io it's different.
252
00:25:55,120 --> 00:25:56,840
Io's a much smaller world
253
00:25:56,840 --> 00:26:00,200
and so it didn't retain
much residual heat.
254
00:26:00,200 --> 00:26:04,080
So, there, the volcanoes are powered
by a different process.
255
00:26:04,080 --> 00:26:06,120
It's known as tidal heating.
256
00:26:12,800 --> 00:26:15,640
The energy that drives Io's
volcanism
257
00:26:15,640 --> 00:26:18,920
doesn't come from heat
stored within the moon.
258
00:26:22,360 --> 00:26:23,960
It's generated by gravity...
259
00:26:26,960 --> 00:26:30,680
..because Io orbits just 350,000km
260
00:26:30,680 --> 00:26:33,520
from the tops of Jupiter's clouds.
261
00:26:50,000 --> 00:26:54,040
Io orbits at about the same distance
from Jupiter
262
00:26:54,040 --> 00:26:55,880
as our moon orbits the Earth.
263
00:26:55,880 --> 00:26:58,440
But because Jupiter is so much more
massive,
264
00:26:58,440 --> 00:26:59,920
Io goes around much more quickly.
265
00:26:59,920 --> 00:27:03,360
In fact, it goes around once every
42 hours.
266
00:27:03,360 --> 00:27:06,040
Now, if Io were Jupiter's only
moon,
267
00:27:06,040 --> 00:27:08,240
that orbit would be circular,
268
00:27:08,240 --> 00:27:09,480
but it isn't.
269
00:27:13,320 --> 00:27:18,000
The next moon out - Europa - goes
round Jupiter precisely once
270
00:27:18,000 --> 00:27:20,040
for every two orbits of Io...
271
00:27:24,520 --> 00:27:27,320
..which means that every second
orbit,
272
00:27:27,320 --> 00:27:29,600
Io and Europa fall into
alignment.
273
00:27:31,800 --> 00:27:35,000
It's what's known as an orbital
resonance.
274
00:27:36,800 --> 00:27:39,120
That gives it a gravitational kick
275
00:27:39,120 --> 00:27:42,320
and that moves Io's orbit
into an ellipse.
276
00:27:42,320 --> 00:27:44,840
Now, that means that the
gravitational force's on Io
277
00:27:44,840 --> 00:27:48,080
are constantly shifting and changing
278
00:27:48,080 --> 00:27:51,120
and that stretches and squashes the
moon,
279
00:27:51,120 --> 00:27:55,800
and heats it up - by friction.
Now, that is called tidal heating
280
00:27:55,800 --> 00:27:59,120
and that is the origin of
Io's volcanoes.
281
00:28:11,520 --> 00:28:14,880
This process raises the temperature
in Io's interior,
282
00:28:14,880 --> 00:28:17,240
which would otherwise be frozen
solid,
283
00:28:17,240 --> 00:28:19,840
to more than 1,000 degrees
Celsius...
284
00:28:23,160 --> 00:28:24,880
..creating its lava lakes...
285
00:28:28,440 --> 00:28:30,960
..and powering immense volcanic
plumes...
286
00:28:33,880 --> 00:28:37,640
..that rise up to 300km
from the moon's surface...
287
00:28:39,360 --> 00:28:41,000
..and out into space.
288
00:28:46,160 --> 00:28:50,040
Io provides the solar system
with a vivid reminder...
289
00:28:51,440 --> 00:28:53,360
..of the giant planet's power.
290
00:29:08,240 --> 00:29:11,000
Jupiter's intense gravitational
field...
291
00:29:13,200 --> 00:29:16,640
..is the source of Io's
volcanism today.
292
00:29:16,640 --> 00:29:19,520
But we don't feel that gravitational
pull here on Earth,
293
00:29:19,520 --> 00:29:22,120
because Jupiter is so far away,
294
00:29:22,120 --> 00:29:25,160
but four-and-a-half billion years
ago,
295
00:29:25,160 --> 00:29:29,440
Jupiter was migrating inwards
towards the inner solar system,
296
00:29:29,440 --> 00:29:33,080
approaching the region where
Mars and Earth were forming.
297
00:29:39,240 --> 00:29:43,440
After passing through what would
become the asteroid belt...
298
00:29:44,880 --> 00:29:47,120
..Jupiter entered the inner
solar system...
299
00:29:52,400 --> 00:29:55,920
..continuing its journey, spiralling
towards the sun.
300
00:30:03,960 --> 00:30:07,640
Back then, the area where Mars
and Earth orbit today
301
00:30:07,640 --> 00:30:10,680
was densely packed with gas and
rock.
302
00:30:18,800 --> 00:30:22,400
But as Jupiter approached,
it wrought havoc...
303
00:30:24,800 --> 00:30:28,240
..scattering the rocky material
in all directions...
304
00:30:30,880 --> 00:30:33,440
..some sent careering into the
sun...
305
00:30:42,360 --> 00:30:45,800
..others thrown out
into interstellar space.
306
00:30:53,320 --> 00:30:57,960
And it's this that may explain our
solar system's unusual structure.
307
00:31:00,920 --> 00:31:02,600
Here's the solar system today.
308
00:31:02,600 --> 00:31:07,320
The sun, the four inner rocky
planets, the asteroids and Jupiter.
309
00:31:07,320 --> 00:31:10,800
And what we think may have happened
is Jupiter made it inwards
310
00:31:10,800 --> 00:31:15,680
through where the asteroids
are, as far in as the orbit of Mars.
311
00:31:15,680 --> 00:31:18,360
And that would have cleaned out
quite a lot of the material
312
00:31:18,360 --> 00:31:22,920
in the inner solar system, leaving
less for the formation of planets.
313
00:31:22,920 --> 00:31:26,840
And that's why we don't see
super-Earths in our solar system.
314
00:31:26,840 --> 00:31:28,880
Those big massive rocky
worlds
315
00:31:28,880 --> 00:31:32,720
that we see in orbit around so many
other stars.
316
00:31:32,720 --> 00:31:36,360
This also might explain
why Mars is so small.
317
00:31:36,360 --> 00:31:40,080
See, if Jupiter was orbiting
in the region that Mars was forming,
318
00:31:40,080 --> 00:31:42,680
there would have been much less
material here.
319
00:31:42,680 --> 00:31:45,520
And that might explain why Mars
320
00:31:45,520 --> 00:31:49,200
is only a tenth of the mass
of Venus and Earth.
321
00:31:59,600 --> 00:32:01,920
Had Jupiter continued to move
inwards,
322
00:32:01,920 --> 00:32:04,840
it would have had a similar effect
on the Earth...
323
00:32:07,280 --> 00:32:10,720
..meaning the world we inhabit
might never have formed.
324
00:32:17,440 --> 00:32:21,920
But just as it looked as if Jupiter
would sweep everything away,
325
00:32:21,920 --> 00:32:25,400
something stopped the giant
planet in its tracks...
326
00:32:32,640 --> 00:32:36,720
..because in the shadows of the
outer solar system,
327
00:32:36,720 --> 00:32:38,720
another planet was forming.
328
00:32:43,400 --> 00:32:46,000
The solar system's second gas
giant...
329
00:32:47,720 --> 00:32:49,120
..Saturn...
330
00:33:01,520 --> 00:33:04,280
..and its birth changed everything.
331
00:33:09,240 --> 00:33:12,520
When a planet forms in a disk
of material around a star,
332
00:33:12,520 --> 00:33:15,400
as Jupiter did in our solar system,
333
00:33:15,400 --> 00:33:19,600
it tends to clear out a gap in the
disk.
334
00:33:19,600 --> 00:33:22,960
Now, the material tends to fall
inwards towards the star.
335
00:33:22,960 --> 00:33:24,760
It's called the accretion
336
00:33:24,760 --> 00:33:27,360
and that drags the whole thing
inwards.
337
00:33:27,360 --> 00:33:30,120
And that's what happened to Jupiter.
338
00:33:30,120 --> 00:33:35,040
But, then, a less massive planet,
Saturn, formed further out.
339
00:33:35,040 --> 00:33:37,440
It cleared out its own disk
340
00:33:37,440 --> 00:33:40,920
and it too fell inwards
towards the sun,
341
00:33:40,920 --> 00:33:43,760
but more quickly
than Jupiter.
342
00:33:43,760 --> 00:33:47,400
That meant that Saturn got
into a resonance with Jupiter.
343
00:33:47,400 --> 00:33:50,240
It went round once in orbit around
the sun
344
00:33:50,240 --> 00:33:52,480
for every two orbits of Jupiter
345
00:33:52,480 --> 00:33:56,560
and that has the effect of cleaning
out the whole region
346
00:33:56,560 --> 00:33:58,560
between the two planets.
347
00:33:58,560 --> 00:34:00,240
And that has the effect,
348
00:34:00,240 --> 00:34:04,480
through a series of complicated
gravitational interactions,
349
00:34:04,480 --> 00:34:06,760
of slowing and stopping the in-fall
350
00:34:06,760 --> 00:34:11,360
and eventually causing the two
planets to move back out again.
351
00:34:11,360 --> 00:34:16,400
And that is what happened to Jupiter
and Saturn in our solar system.
352
00:34:24,440 --> 00:34:26,760
Saturn caused Jupiter to retreat...
353
00:34:28,000 --> 00:34:30,040
..leaving behind just enough
material
354
00:34:30,040 --> 00:34:32,480
from which the inner planets could
form.
355
00:34:35,960 --> 00:34:37,400
Mercury.
356
00:34:40,160 --> 00:34:41,440
Venus.
357
00:34:44,280 --> 00:34:45,720
Mars.
358
00:34:51,520 --> 00:34:53,720
And our home...
359
00:34:53,720 --> 00:34:55,160
..the Earth.
360
00:35:01,600 --> 00:35:05,240
By preventing the formation of much
larger super-Earths,
361
00:35:05,240 --> 00:35:08,240
Jupiter allowed our planet to grow.
362
00:35:22,880 --> 00:35:27,960
And even as Jupiter's reign of
terror was drawing to a close,
363
00:35:27,960 --> 00:35:31,840
it provided one last parting
gift to our world.
364
00:35:46,200 --> 00:35:49,680
The young Earth formed in an arid
region of the inner solar system.
365
00:35:49,680 --> 00:35:53,160
There was very little water
that close to the sun,
366
00:35:53,160 --> 00:35:56,800
but as the Earth was forming,
Jupiter was already tacking back
367
00:35:56,800 --> 00:35:59,240
outwards again into the outer solar
system
368
00:35:59,240 --> 00:36:03,280
through the region that we now call
the asteroid belt,
369
00:36:03,280 --> 00:36:08,000
a region populated by many icy,
water rich comets and asteroids.
370
00:36:08,000 --> 00:36:10,720
And they were scattered back inwards
again,
371
00:36:10,720 --> 00:36:13,920
bringing water back into the inner
solar system.
372
00:36:13,920 --> 00:36:16,120
So, I think it is quite a wonderful
thought,
373
00:36:16,120 --> 00:36:21,480
that Earth is a water world today
because of the motion inwards
374
00:36:21,480 --> 00:36:25,040
and then back outwards again
of the massive planet Jupiter.
375
00:36:31,320 --> 00:36:37,000
This idea does seem quite
contrived, almost fantastical,
376
00:36:37,000 --> 00:36:40,080
but the more we learn about
the formation of solar systems,
377
00:36:40,080 --> 00:36:43,920
and the more we try to model
a system like ours,
378
00:36:43,920 --> 00:36:47,560
with four terrestrial, water-rich
planets close to the star
379
00:36:47,560 --> 00:36:50,520
and then the gas giants further out,
380
00:36:50,520 --> 00:36:54,920
the more we learn that perhaps all
these things had to happen,
381
00:36:54,920 --> 00:36:59,360
these unlikely movements and
interactions between the planets,
382
00:36:59,360 --> 00:37:05,600
in order to produce a system like
ours and a planet like ours.
383
00:37:05,600 --> 00:37:09,680
So, places like this may
be extremely rare.
384
00:37:24,960 --> 00:37:28,200
Today, Jupiter has settled
into a regular orbit
385
00:37:28,200 --> 00:37:31,640
back beyond the far edge
of the asteroid belt...
386
00:37:34,520 --> 00:37:38,560
..its days of marauding through
the solar system at an end.
387
00:38:21,840 --> 00:38:24,480
Jupiter has been established
in a stable orbit
388
00:38:24,480 --> 00:38:26,720
for almost four billion years.
389
00:38:26,720 --> 00:38:30,120
If I was to sit here on Earth 3.8
billion years ago
390
00:38:30,120 --> 00:38:32,880
when life began and look
up into the night sky,
391
00:38:32,880 --> 00:38:36,640
I would have seen it shining
there as a point of light
392
00:38:36,640 --> 00:38:40,640
the same as it looks today,
distant and seemingly detached.
393
00:38:40,640 --> 00:38:44,600
And it's remained that way for the
vast expanse of time it's taken
394
00:38:44,600 --> 00:38:46,880
for evolution by natural selection
395
00:38:46,880 --> 00:38:52,360
to transform those first populations
of organisms into all this,
396
00:38:52,360 --> 00:38:55,960
to transform the Earth into an oasis
of life
397
00:38:55,960 --> 00:38:58,000
in the desert of the solar system.
398
00:39:08,560 --> 00:39:12,720
But Jupiter's influence over the
Earth remains to this day...
399
00:39:17,080 --> 00:39:20,920
..and that's because, despite its
great distance from us...
400
00:39:22,360 --> 00:39:26,000
..it retains a vice-like grip
over the asteroid belt.
401
00:39:41,000 --> 00:39:43,080
It's easy, I think quite natural,
402
00:39:43,080 --> 00:39:45,560
to think of the asteroid belt
as a single structure.
403
00:39:45,560 --> 00:39:48,120
A sort of ring of rock surrounding
the sun.
404
00:39:48,120 --> 00:39:50,800
But that's not
what it's like at all.
405
00:39:50,800 --> 00:39:54,800
In reality, each one of those
millions and millions of pieces
406
00:39:54,800 --> 00:39:58,840
of rock is following its own
individual orbits.
407
00:39:58,840 --> 00:40:01,280
And this remarkable animation
408
00:40:01,280 --> 00:40:05,040
is made up of ten years
of astronomical observations.
409
00:40:05,040 --> 00:40:09,040
And every point you see
on this animation...
410
00:40:09,040 --> 00:40:12,560
..is a single asteroid,
apart from all the planets.
411
00:40:12,560 --> 00:40:16,800
And so you see Earth and Mars
and Venus whizzing around the sun.
412
00:40:16,800 --> 00:40:20,240
But the interesting one
is Jupiter...
413
00:40:20,240 --> 00:40:23,320
..orbiting just outside the asteroid
belt.
414
00:40:24,520 --> 00:40:27,640
What you can see is that the
asteroid belt
415
00:40:27,640 --> 00:40:29,600
dances to Jupiter's tune.
416
00:40:29,600 --> 00:40:32,760
It's the conductor of the asteroid
belt, if you like.
417
00:40:32,760 --> 00:40:36,960
There are complex patterns
here, but there's also structure.
418
00:40:38,960 --> 00:40:42,600
And the reason for that is
the delicate interplay
419
00:40:42,600 --> 00:40:44,840
between the gravitational pull
of the sun
420
00:40:44,840 --> 00:40:47,800
and the gravitational force from
Jupiter.
421
00:40:49,680 --> 00:40:51,000
Now, what can happen is that
422
00:40:51,000 --> 00:40:53,760
perhaps because of an interaction
between two asteroids,
423
00:40:53,760 --> 00:40:56,000
perhaps they collide with each
other,
424
00:40:56,000 --> 00:40:59,640
or perhaps on their orbit
they line-up perfectly with Jupiter
425
00:40:59,640 --> 00:41:01,840
and get an extra gravitational kick,
426
00:41:01,840 --> 00:41:04,720
those asteroids can be disturbed
from this structure
427
00:41:04,720 --> 00:41:07,680
and be sent
inwards to the inner solar system.
428
00:41:07,680 --> 00:41:12,800
And by that mechanism, Jupiter
has a profound influence
429
00:41:12,800 --> 00:41:15,160
on the planets closer to the sun.
430
00:41:25,120 --> 00:41:28,040
Around 100 million years ago,
431
00:41:28,040 --> 00:41:32,360
an asteroid 10km across was ejected
from the asteroid belt.
432
00:41:36,840 --> 00:41:39,920
Dislodged by Jupiter's gravity,
433
00:41:39,920 --> 00:41:43,320
it was set on a collision
course with the Earth.
434
00:42:02,720 --> 00:42:06,320
When it struck, it generated
a fireball so hot,
435
00:42:06,320 --> 00:42:11,520
anything within a 1,000km
radius would have died instantly.
436
00:42:20,240 --> 00:42:23,960
The impact threw 300 billion
tonnes of sulphur
437
00:42:23,960 --> 00:42:25,200
into the atmosphere.
438
00:42:34,360 --> 00:42:37,600
And during the nuclear winter
that followed,
439
00:42:37,600 --> 00:42:42,640
75% of all species were wiped
from the face of the Earth.
440
00:42:50,560 --> 00:42:52,600
In one fell swoop,
441
00:42:52,600 --> 00:42:56,040
Jupiter changed the course
of our planet's history.
442
00:43:08,440 --> 00:43:11,000
There are a few places on Earth
today
443
00:43:11,000 --> 00:43:14,040
where you can catch a glimpse
of lost worlds,
444
00:43:14,040 --> 00:43:17,680
you can see Earth as it was millions
of years in the past
445
00:43:17,680 --> 00:43:21,440
and perhaps glimpse the Earth as it
might have been.
446
00:43:21,440 --> 00:43:23,000
And this is one of them.
447
00:43:23,000 --> 00:43:25,320
Today, this is the Colorado Plain,
448
00:43:25,320 --> 00:43:27,040
over a kilometre in altitude,
449
00:43:27,040 --> 00:43:29,760
south of Denver close
to the Rocky Mountains,
450
00:43:29,760 --> 00:43:34,400
but 200 million years ago,
this was at sea level.
451
00:43:34,400 --> 00:43:38,920
It was an ancient lake and the
ghosts of those lost worlds,
452
00:43:38,920 --> 00:43:41,560
the imprints of the past, can be
seen over there,
453
00:43:41,560 --> 00:43:45,800
because there are literally
thousands of dinosaur footprints.
454
00:44:11,760 --> 00:44:14,560
And here they are, the dinosaur
footprints.
455
00:44:14,560 --> 00:44:17,720
I find this absolutely remarkable.
456
00:44:17,720 --> 00:44:20,960
This is the footprint
of a sauropod dinosaur.
457
00:44:20,960 --> 00:44:24,440
That's one of the big ones. The big
herbivores with the long necks.
458
00:44:24,440 --> 00:44:26,840
This animal would have weighed
about 30 tonnes.
459
00:44:26,840 --> 00:44:30,960
It was tall enough to peer
over a two-storey house.
460
00:44:30,960 --> 00:44:34,560
What happened here is, probably
a herd of them, a group of them
461
00:44:34,560 --> 00:44:38,240
came lumbering across this lake bed
and, then,
462
00:44:38,240 --> 00:44:41,440
perhaps that same afternoon,
predators came,
463
00:44:41,440 --> 00:44:43,880
maybe following the herd.
464
00:44:43,880 --> 00:44:46,120
And that's these footprints here.
465
00:44:46,120 --> 00:44:48,840
The allosaurus', these three-toed
footprints.
466
00:44:48,840 --> 00:44:52,240
Much smaller animal, maybe
about twice the height of me,
467
00:44:52,240 --> 00:44:55,480
about two tonnes, very nimble and
agile.
468
00:44:55,480 --> 00:45:00,160
So, you see a whole story
played out here, frozen in time.
469
00:45:14,400 --> 00:45:17,560
Today, just their traces remain...
470
00:45:22,920 --> 00:45:24,960
..but were it not for Jupiter...
471
00:45:26,400 --> 00:45:28,080
..they might still be here.
472
00:45:45,880 --> 00:45:47,920
There are so many chance events,
473
00:45:47,920 --> 00:45:50,360
not only throughout the history of
Earth,
474
00:45:50,360 --> 00:45:53,240
but also spanning the entire history
of the universe
475
00:45:53,240 --> 00:45:57,800
for 13.8 billion years, without
which we wouldn't exist.
476
00:45:57,800 --> 00:46:00,160
There's an unbroken chain of life
stretching back
477
00:46:00,160 --> 00:46:02,040
four billion years here on this
planet.
478
00:46:02,040 --> 00:46:05,080
You interrupt or interject
at any point
479
00:46:05,080 --> 00:46:07,960
and life on Earth is different.
480
00:46:07,960 --> 00:46:11,880
But having said that, there are
major events that affected life.
481
00:46:11,880 --> 00:46:15,440
And one of them is the asteroid
that wipes out the dinosaurs.
482
00:46:15,440 --> 00:46:18,600
And, in that sense, it is certainly
true to say
483
00:46:18,600 --> 00:46:21,400
that without Jupiter, we wouldn't be
here.
484
00:46:38,480 --> 00:46:41,240
The godfather of the planets
paved the way for us
485
00:46:41,240 --> 00:46:42,960
to inherit the Earth.
486
00:46:48,800 --> 00:46:50,680
And although it occasionally
flings rocks
487
00:46:50,680 --> 00:46:52,480
from the asteroid belt our way...
488
00:46:53,720 --> 00:46:56,160
..it also protects us...
489
00:47:02,680 --> 00:47:05,000
..because for objects heading
towards the Earth
490
00:47:05,000 --> 00:47:08,160
from the far reaches of the solar
system,
491
00:47:08,160 --> 00:47:11,720
Jupiter's gravitational
field acts as a shield.
492
00:47:17,160 --> 00:47:20,440
Around a century ago, a lump
of rock and ice
493
00:47:20,440 --> 00:47:25,680
4km across and weighing
17 billion tonnes...
494
00:47:27,360 --> 00:47:30,480
..was hurtling towards the inner
solar system...
495
00:47:34,960 --> 00:47:38,000
..until Jupiter intervened.
496
00:47:40,840 --> 00:47:45,920
Five, four, three, two, one...
497
00:47:45,920 --> 00:47:48,040
We have ignition and lift off of
Atlantis
498
00:47:48,040 --> 00:47:51,240
and the Galileo Spacecraft
bound for Jupiter.
499
00:47:52,600 --> 00:47:56,800
70 years later, we witnessed
just how effective a shield
500
00:47:56,800 --> 00:47:58,480
Jupiter can be.
501
00:48:07,480 --> 00:48:09,960
Onboard the space shuttle
Atlantis...
502
00:48:11,280 --> 00:48:12,720
..the Galileo orbiter.
503
00:48:22,560 --> 00:48:25,040
Three years after Galileo launched,
504
00:48:25,040 --> 00:48:30,000
comet Shoemaker-Levy-9 had been
captured by Jupiter's gravity.
505
00:48:39,000 --> 00:48:41,800
Locked in the giant planet's
embrace...
506
00:48:43,800 --> 00:48:46,880
..tidal forces now began to tear
it apart.
507
00:48:54,240 --> 00:48:56,200
Its journey cut short...
508
00:48:57,240 --> 00:48:59,840
..the comet now faced annihilation.
509
00:49:11,440 --> 00:49:14,000
After crossing the inner
solar system,
510
00:49:14,000 --> 00:49:16,920
Galileo passed through the asteroid
belt...
511
00:49:20,360 --> 00:49:22,800
..approaching the spots from where
it would witness
512
00:49:22,800 --> 00:49:24,640
the comet's final moments.
513
00:49:35,440 --> 00:49:40,480
On July 16th, Galileo saw the first
fragments of the comet
514
00:49:40,480 --> 00:49:43,120
enter Jupiter's southern hemisphere.
515
00:49:55,300 --> 00:49:57,760
Pieces of comet Shoemaker-Levy-9
516
00:49:57,760 --> 00:50:00,960
struck Jupiter over the course of
six days.
517
00:50:05,000 --> 00:50:08,680
It was the first time a comet strike
had ever been witnessed.
518
00:50:29,920 --> 00:50:33,040
The most destructive impact released
energy
519
00:50:33,040 --> 00:50:36,200
equivalent to six million megatons
of TNT...
520
00:50:37,960 --> 00:50:43,320
..leaving behind a giant dark
cloud 12,000km across.
521
00:50:52,800 --> 00:50:57,600
By capturing objects
and incinerating them on impact...
522
00:50:57,600 --> 00:51:01,680
..Jupiter sweeps up bodies
from the outer solar system...
523
00:51:01,680 --> 00:51:04,480
..that might otherwise collide
with Earth.
524
00:51:17,320 --> 00:51:19,280
Jupiter,
525
00:51:19,280 --> 00:51:22,480
the oldest and largest of
the planets,
526
00:51:22,480 --> 00:51:25,200
is the godfather of our
solar system.
527
00:51:28,800 --> 00:51:29,880
In youth...
528
00:51:30,880 --> 00:51:32,560
..it went on the rampage.
529
00:51:41,200 --> 00:51:44,120
For some young planets, it spelt
disaster.
530
00:51:49,440 --> 00:51:52,280
But for others, like our own
world,
531
00:51:52,280 --> 00:51:54,720
it cleared the way for their
formation.
532
00:52:03,440 --> 00:52:06,280
And in adulthood, it created
the conditions
533
00:52:06,280 --> 00:52:07,920
that allowed us to rise...
534
00:52:12,800 --> 00:52:16,000
..so we owe Jupiter a great debt.
535
00:52:17,800 --> 00:52:20,920
But as the dinosaurs found
to their cost,
536
00:52:20,920 --> 00:52:24,560
it's a debt that could be recalled
at any time.
537
00:52:29,440 --> 00:52:30,720
To the naked eye,
538
00:52:30,720 --> 00:52:34,120
Jupiter is one of the brightest
points of light in the night sky,
539
00:52:34,120 --> 00:52:38,120
and through a small telescope, it is
a beautiful banded world.
540
00:52:38,120 --> 00:52:40,640
But it feels distant, eternal,
541
00:52:40,640 --> 00:52:44,480
disconnected from events
here on Earth.
542
00:52:44,480 --> 00:52:48,320
But the more we've understood about
the history of the solar system,
543
00:52:48,320 --> 00:52:51,360
the more we've come to understand
that that is not the case.
544
00:52:51,360 --> 00:52:55,840
Jupiter has played an important
and perhaps decisive role
545
00:52:55,840 --> 00:52:59,320
in the stories of all the planets,
including Earth.
546
00:52:59,320 --> 00:53:02,760
So, the solar system is just that.
It's a system.
547
00:53:02,760 --> 00:53:06,800
Complex, interconnected and
interdependent.
548
00:53:06,800 --> 00:53:11,000
So, next time you see Jupiter,
just hold your gaze.
549
00:53:11,000 --> 00:53:16,160
Maybe think for a minute, because it
is so much more than just a point
550
00:53:16,160 --> 00:53:18,200
of light, or a planet, even.
551
00:53:18,200 --> 00:53:21,600
It is the great sculptor
of the solar system,
552
00:53:21,600 --> 00:53:24,480
the destroyer and creator of worlds.
553
00:54:06,040 --> 00:54:08,160
I think people are drawn
in by Jupiter
554
00:54:08,160 --> 00:54:11,040
because it's very mysterious.
555
00:54:11,040 --> 00:54:14,440
It's covered by clouds that hide
what's underneath.
556
00:54:14,440 --> 00:54:15,720
It's very violent.
557
00:54:17,480 --> 00:54:19,520
And it's very intimidating.
558
00:54:21,600 --> 00:54:23,480
It's also very beautiful.
559
00:54:24,480 --> 00:54:26,680
It has all these things
going on
560
00:54:26,680 --> 00:54:29,680
and it's hard not to be taken in.
561
00:54:29,680 --> 00:54:34,960
T-minus ten, nine, eight, seven,
six...
562
00:54:34,960 --> 00:54:37,400
Such is Jupiter's mystique,
563
00:54:37,400 --> 00:54:40,440
it's been a recurring
target for space exploration.
564
00:54:40,440 --> 00:54:47,240
And lift off of the Atlas V with
Juno on a trek to Jupiter.
565
00:54:47,240 --> 00:54:51,840
In 2011, Nasa launched its latest
mission - Juno.
566
00:55:00,960 --> 00:55:03,280
When we launched the Juno spacecraft
567
00:55:03,280 --> 00:55:06,280
away from the Earth out towards
Jupiter,
568
00:55:06,280 --> 00:55:11,480
we didn't have enough speed to get
away out of the gravity of the sun,
569
00:55:11,480 --> 00:55:14,400
so we actually had to come back
to Earth,
570
00:55:14,400 --> 00:55:16,720
get a gravity assist
from Earth,
571
00:55:16,720 --> 00:55:18,640
and then go out to Jupiter.
572
00:55:23,120 --> 00:55:26,880
After travelling for five
years, Juno finally arrived.
573
00:55:31,400 --> 00:55:35,320
This is a mission that goes closer
to the planet in its orbit
574
00:55:35,320 --> 00:55:37,360
than any other mission ever has.
575
00:55:37,360 --> 00:55:42,000
Only a few thousand kilometres from
the cloud tops and very, very fast.
576
00:55:42,000 --> 00:55:44,360
We go from pole to pole in two
hours,
577
00:55:44,360 --> 00:55:47,960
slipping between the radiation belts
in the cloud tops,
578
00:55:47,960 --> 00:55:50,760
getting the data as fast as we can
and getting out.
579
00:55:52,840 --> 00:55:55,520
So, in every way, Juno is breaking
new ground
580
00:55:55,520 --> 00:55:59,880
and that's allowed us to see things
that we couldn't have ever imagined.
581
00:56:04,680 --> 00:56:08,600
Juno's mission is to explore
the planets inside and out.
582
00:56:11,120 --> 00:56:14,440
And amongst the many scientific
instruments it has on board
583
00:56:14,440 --> 00:56:17,360
is its camera, JunoCam.
584
00:56:19,480 --> 00:56:24,360
You see all these swirls, you see
all sorts of spots coming up.
585
00:56:24,360 --> 00:56:30,120
You see all these vortices, you see
dramatic storm systems interacting.
586
00:56:35,640 --> 00:56:38,680
It's mind-blowingly beautiful
pictures
587
00:56:38,680 --> 00:56:41,480
that this little camera
has been taking.
588
00:56:44,200 --> 00:56:47,600
JunoCam was able to see
the Great Red Spot from up close.
589
00:56:49,280 --> 00:56:51,600
We can see height to the clouds.
590
00:56:51,600 --> 00:56:54,320
We can see features that look
like storms.
591
00:56:54,320 --> 00:56:58,600
Maybe it's hailing or snowing
ammonia on Jupiter.
592
00:57:02,040 --> 00:57:07,320
And the most startling thing that we
saw from JunoCam's imagery
593
00:57:07,320 --> 00:57:10,360
was that the poles of Jupiter
are actually blue.
594
00:57:14,200 --> 00:57:16,760
They are nothing like the orange
and white planet
595
00:57:16,760 --> 00:57:19,520
that we grew up thinking about as
children.
596
00:57:24,760 --> 00:57:28,600
Juno has just begun to unlock
Jupiter's secrets.
597
00:57:31,440 --> 00:57:33,320
And so, at last,
598
00:57:33,320 --> 00:57:36,960
the godfather of the planets
has begun to talk.
599
00:57:52,200 --> 00:57:56,240
A planet that began life
as an unremarkable rocky world...
600
00:57:57,840 --> 00:58:02,000
..but transformed into one
of the jewels of the solar system...
601
00:58:03,600 --> 00:58:08,680
..where shimmering rings of ice
harbour a potential home for life.
602
00:58:11,320 --> 00:58:12,520
Saturn.
603
00:58:16,400 --> 00:58:18,640
Journey through our solar system
with this free poster
604
00:58:18,640 --> 00:58:20,960
produced by the Open University
605
00:58:20,960 --> 00:58:23,680
and discover more about its planets
and moons.
606
00:58:28,400 --> 00:58:32,640
Order your free
copy by calling...
607
00:58:32,640 --> 00:58:38,320
Or go to...
608
00:58:38,320 --> 00:58:41,360
..and follow the links
to the Open University.
51334
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