our planet was born in fire
then grew With
Disaster yet even then the Elements of
Life were
present water was soon present on the
surface when calm it would provide a
sheltered cradle for the first life on
Earth
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4 and a half billion years ago the earth
was a very different world under layers
of thick gaseous clouds was a planet
still hot from its birth with an
atmosphere both dense and
crushing the early planet was probably
only a tenth of the size that it is
today but it was to grow and that chance
and violent growth would prove crucial
to Life's history and to what we are
today
the early solar system was far more
crowded than
now where today the four inner planets
orbit 4 and a half billion years ago
were scores of smaller planets orbiting
the Sun orbits of some were drawn by
gravitational force towards each other
Encounters of awesome magnitude were
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unavoidable the force and heat of those
collisions melted The Rock but gravity
would hold the two together and then
weld them into one with each Collision
the planet would grow
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larger we believe that of the four
innermost planets Mercury was formed by
only one or two such
collisions while Venus almost the size
of earth was formed by eight
Mars may have escaped any
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collisions but Earth grew largest
perhaps from as many as 10
impacts and the last impact 4 and a half
billion years ago would have a profound
effect Upon Our World
the giant body crashed into the center
of the planet and gave Earth its iron
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core the lighter debris was cast off
into space and then drawn into orbit
around the enlarged planet
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for some millions of years the earth had
Rings like the planet
Saturn smaller collisions continued and
from that debris was born
armoon at the Earth's center is a
massive ball of ir iron known as the
core an outer core of molten iron swirls
around it next is the mantle slow moving
hot rock 1,800 M thick in contrast the
crust the part we live on is
thin in fact it's broken into pieces
called
plates 4.6 billion years ago a
continuous full rain of meteorites
pounded the molten
Earth each strike brought with it more
rock making our planet bigger and
scattering Metals over the
surface then a giant asteroid struck
its massive iron core didn't stop on the
surface it sank towards the center and
it attracted all the Earth's metals to
it as it
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went the asteroids lighter Rocky debris
went spinning around the
earth the fragments were drawn together
by
gravity with in a year they formed our
moon that's why the moon has no metal at
its
core and it's why metal is rare in the
Earth's crust it arrived much later in
meteorites from Outer
Space if we want much more metal we must
go to the Earth's core
it's made mostly of iron and nickel but
1% is
gold that may not sound like much but
the core is so vast that its gold could
cover all the land on Earth Knee Deep
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as
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