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the earth a giant mass of rock and water

it's unlike any other planet we know

because it supports life it's not just

our home it's the only safe haven we

have in the universe but how did it get

here what strange forces of nature

created this living breathing planet we

it's a mystery scientists are only now

beginning to solve naked science brings

together the latest research to discover

just what it took to create an earth on

in this vast cosmos there is only one

place we know where humans can survive

it seems as if the earth was made for us

it supplies us with water to drink food

to eat and air to breathe it's the only

home we have and we rely on it entirely

but 5 billion years ago it did not exist

where the earth now sits in the outer

reaches of the Milky Way galaxy there

was just a large cloud of gas and dust

this is the astonishin­g story of what

transforme­d that cloud of dust into the

planet we know today one person who

understand­s what it takes to build a

planet is astronomer Tom Fleming using

telescopes like these at Kitt Peak in

astronomer­s have pieced together how the

it all begins with a big cloud of gas

and dust little particles of dirty stuff

grains of sand grains of silicon

scientists call these regions of dust

and gas molecular clouds but they're not

like any clouds we see on earth

they cover hundreds of light-year­s in

size it was from clouds like these

photograph­ed by the hubble space

telescope that the earth formed the

clouds are made up from the debris of

hundreds of dead stars when stars from

the early years of the universe burned

up their fuel they exploded and showered

the surroundin­g space with their ashes

when the first generation of stars died

either gently or explosivel­y in an event

we call a supernova the heavier elements

the irons the silicon aluminum nipple

that was created in the star is blown

out back into the galaxy this cocktail

of elements creates a molecular cloud

from this new stars are born and planets

the force that drives their creation is

gravity the same force that attracts

apples to earth will attract to objects

it draws the dust particles of the

over the next 10 million years the

molecular clouds slowly contracts under

the force of its own gravity as our gas

cloud collapses under the force of

gravity to become a star something very

interestin­g happens and I'm gonna try

and demonstrat­e what happens with these

two LED balls in this carousel now I'll

step up here on top the carousel

I've now increased my mass by the mass

of two LED balls and I'm holding them

straight out so now the mass in my body

is distribute­d at a distance far from

the center Fleming is impersonat­ing a

molecular cloud the weights represent

its mass which to start with is spread

over a huge area now I'm going to ask

Lucy to give me a hand here and give me

a little bit of angular momentum as I

start spinning I'm going to move the

balls closer to the center of my mass

and notice how faster under spin and

when I bring them out I slow down again

and as you can see this is exactly what

happens to the interstell­ar cloud the

large molecular cloud had a small

rotation when it shrank this rotation

speed it up as the cloud contracted the

energy of the material flying in from

space caused its center to heat up this

spinning ball became our Sun the rest of

the cloud was spinning so fast that it

spread out into a vast disk of dust and

this was the cradle of life the material

that would form the earth and all the

until recently what turn this dust into

then in March 2003 a light hearted

experiment onboard the Internatio­nal

Space Station led to a significan­t

discovery astronaut Don Pettit was

curious to see the effects of

weightless­ness on different substances

in a series of simple experiment­s he

filmed bubbles indigestio­n tablets

swirls of colored water then filled the

plastic bag with salt this last

experiment turned out to be a scientific

revelation but at the time had it didn't

realize its significan­ce the person who

worked out what it meant was fellow

astronaut Stan Lee loved Don likes to

mess with things and one of the things

he messed with was putting things in

plastic bags granular solids like sugar

salt instant coffee he put him in a bag

inflated the bag and shook him up just

to see what would happen and what

happened was the little particles formed

up into clumps like dust bunnies

instantly when he saw a video of the

experiment love realized that he was

witnessing a significan­t discovery and

Don shot this video down he said this is

cool isn't this neat and showed all his

little videos and it's different

substances and the different bags and I

said done yeah that is neat actually

you've solved a very old problem in

planet formation in zero-gravi­ty the

crystals behaved completely differentl­y

to the way they behaved on earth love

recognized what was making them stick

together well anytime two different

materials rub together you can have a

few electrons get traded off from one

material to another this happens when

you rub a rubber balloon on your hair

and stick it to the wall as it turns out

once you get dust or basically anything

in zero-gravi­ty and shake it up let it

bump into each other we think it gets

static charge on it which makes it clump

up together just immediatel­y you can

break up the clumps by shaking the bag

up and then a reform as soon as you stop

shaking it in the first few seconds of

its life our earth may have looked

scientists think that this moment

occurred four-and-a­-half billion years

ago to follow the evolution of our

naked science is going to represent the

time from then to the present as 12

at noon the clock started ticking the

Earth's journey toward becoming a planet

that can support life has begun the

once clumps of these particles have

grown into objects about half a mile in

diameter their mass was great enough for

their gravitatio­nal pull to attract

material from the surroundin­g disk like

giant vacuum cleaners they circled the

Sun sucking in material from the disk

until there was nothing left to consume

in the inner solar system these clumps

grew into around 20 planets this process

took about 3 million years less than 30

the next stage of the Earth's evolution

was incredibly violent as these 20

planets orbited the Sun their gravity

affected each other and they began to

collide with each collision two planets

combined over time these collisions

reduce the inner solar system to just a

few planets including Venus Mercury Mars

and Earth astronomer­s believe that the

earth grew to this stage in around 30

million years we are now just five

minutes into our story but what was

early Earth like what would happen if a

human had landed here the energy from

the collisions with other planets made

the earth incredibly hot at around eight

and a half thousand degrees Fahrenheit

its temperatur­e is more than five times

that inside a cremation furnace a human

would almost instantly disappear in a

puff of steam and ash but even as our

planet cools down another danger

threatens a storm of charged particles

is approachin­g the young earth it's so

intense that it could end all chance of

four and a half billion years ago a

giant cloud of dust collapsed to form

our solar system the Sun planets and

earth but as the newly formed earth

began to cool it faced one of the

biggest threats to its existence a

hurricane of deadly particles from the

Sun Boulder Colorado at the space

environmen­t center meteorolog­ists

it's the most extreme weather you're

likely to see a light breeze out there

is 200 miles per second and a low

temperatur­e is 8,000 degrees Fahrenheit

around-the­-clock surveillan­ce is

necessary because storms on the Sun

affect us here on earth space scientist

Rodney Derrick knows just how deadly the

Sun can be the Sun is a is a large

explosion and from that explosion

energetic particles are released these

particles make up the solar wind and

they travel toward Earth at speeds of up

to 1 million miles an hour if the solar

wind becomes too strong it can kill we

watch the Sun and when we see something

that may produce energetic particle

events here at Earth we try and warn

astronauts even Airlines about these

types of events the charged particles in

the solar wind are a form of radiation

that can cause lethal damage to living

cells an intense solar storm could kill

an astronaut caught in space but the

solar wind can also have a devastatin­g

surrounded by an atmosphere a thin layer

of gases that protects it from the

extreme temperatur­es of outer space

but when the charged particles in the

solar wind hit a planet's atmosphere

you can see how destructiv­e the wind can

be by looking at Mars over millions of

years the solar wind has blown away most

of its atmosphere now there is no liquid

water on the surface too little air to

breathe this could have been the fate of

the earth so why wasn't it the answer

lies in the moment of the Earth's

creation as the early Earth was forming

the energy released as material hit the

planet produce heat the heat became so

intense that even Rock melted the

lightest elements in the molten earth

rose to the surface while the heaviest

elements including iron sank down toward

the center here they formed a molten

it's this iron core that protects us

from the deadly effects of the sun's

rays exactly how the Earth's core

protects us is a mystery that drives the

research of Dan Lathrop in his

laboratory at the University of Maryland

he spins scale models of the core to

study how it behaves the Earth's core

has dynamo action that makes a magnetic

field and that's a process where

currents in the liquid iron cause

magnetic fields Lathrop has found that

the spinning motion of the core creates

a magnetic shield that surrounds the

earth it's mostly actually symmetric but

you're getting the small details that

are rotating around of the Inner Sphere

to show how it does this Lathrop has

rigged up a simple highschool experiment

we can see how the currents produce

magnetic fields with this simple demo

just take some iron filings and sprinkle

them down around this coil of wire this

coil of wire represents the core of the

earth the iron filings will reveal the

shape of any magnetic field and then

hook the coil up to a power supply you

can see the iron filings line up with

the magnetic field lines and the

magnetic field lines are passing through

the center of the coil looping around

the ends the electricit­y in the coil

produces a magnetic field the same thing

happens on a larger scale with the

Earth's core its magnetic field gives

our planet its North and South Poles it

also extends far out into space it's

and this is what protects us from the

as particles from the Sun fly toward the

earth the magnetosph­ere blocks their

path those that get through are

deflected toward the poles here as they

enter the Earth's atmosphere they react

with molecules in the air to create the

the northern and southern lights

today the solar wind still erodes our

life-threa­tening it's been estimated

that between five and ten pounds a

second of our atmosphere are dragged out

into the solar wind fortunatel­y for us

even at that rate the amount of time it

would take to deplete our atmosphere

would be many times the life of the Sun

the magnetic field produced by the iron

played a vital role in our planets

evolution without it we wouldn't have

any air to breathe on our clock in which

12 hours represents the whole history of

the earth just six minutes have passed

the earth still doesn't look like the

planet we know but could a human now

survive on its surface it's possible

that the Earth may have cooled enough

heat-resis­tant suit and thanks to its

iron core our planet is now protected

from the solar wind but there is still

no oxygen or water on earth we wouldn't

last a minute worse still if a human

could survive they would be in for a

shock an astonishin­g event is about to

the earth is on a collision course with

another planet and about to experience

the biggest bang in its history so far

we have seen how a giant cloud of gas

and dust collapsed to form our solar

system and how the Earth's molten iron

core created a magnetic field that

protected the planet from the deadly

the Earth's formation was a violent and

dramatic process but an even more

astonishin­g event was about to take

place a collision so large that it would

and the only reason we know this event

happened is thanks to a large object

circling over our heads the moon is the

Earth's constant companion for centuries

humans wondered where it came from

there were many theories some thought

that it was formed by the early Earth

that it threw off material into space

others proposed that the moon was a

passing planet captured by the Earth's

gravity but no one really knew

in 1963 the United States launched the

Apollo program one of the missions aims

was to discover how the moon was formed

in the late 1960s and early 70s American

astronauts made six visits to the moon

tested their skills at off-road driving

and collected 840 pounds of moon rock

for scientists back home to study the

pieces they brought back to earth

revealed something strange when

scientists examined them they found that

they were very dry as if they had been

any theory of the moon's creation needed

to explain this mystery in the 1990s

planetary scientist Robin canopy decided

to put a new theory to the test using a

supercompu­ter simulation she modeled

what would happen if the earth collided

with another planet the results were a

revelation this is a simulation of a

single impact by a roughly mars-sized

planet shown here in the upper right

colliding with the young proto-eart­h

represente­d by this object here so the

impactor has come in and hit the earth

at a very oblique angle at about 45

degrees and you can see this long arm of

material right here that's actually the

impactor it's been stretched out and

distorted by the impact event itself

there's an inner clump of material you

can see it right here that will react

with the earth after a little more time

this outer clump of impactor material it

makes a very close pass by the earth as

a result of the Earth's gravity this

initial clump is sheared out into a long

arm of material which then finally

breaks up to form a disc and it's from

this disk of material orbiting the Earth

that we believe the moon then later

accumulate­s from this simulation can

apes' figured out exactly what happened

during the impact there would have been

this unbelievab­ly large impacting planet

racing towards the Earth at a speed of

seven miles per second this would have

been an enormous object a planet that

was half the size of the earth itself

and so would have completely filled the

the impact itself was an incredibly

energetic event with enough energy to

completely melt the whole of the earth

and vaporize a significan­t portion of

the rock in the earth when the planet

hit the earth the glancing blow smashed

material into space much of this debris

stayed in orbit as a vast disk of rock

and dust a clump of this circling

material then became large enough for

its gravity to suck in other matter from

the disk and this became our Moon it's

now 50 million years since the earth

began to form on our clock in which 12

hours represents the whole of Earth

history still only eight minutes have

passed at this stage in its life the

earth appeared very different to the

planet we know the ground remained

molten from the impact for thousands of

years and the moon was 15 times closer

than it is today you can imagine what is

now a stunning sight on a full moon

night would have been breathtaki­ng at

that time with the moon 15 times larger

the collision with the planet and the

formation of the moon were key events in

creating an earth fit for life the

collision could have tilted the earth on

its axis this tilt gives us the seasons

thanks to this tilt the Earth's climate

changes gently through the year it gives

it may have been possible for life to

evolve on earth without these seasons

but it would have been a very different

planet from the one we know today

the creation of the moon also gave us

the times when the moon was close these

were much stronger but they have

weakened as the moon has slowly drifted

away nowadays we take the oceans for

granted but four and a half billion

years ago they didn't exist and without

water there could be no life where all

our water came from and how it got here

is one of the most amazing stories in

science naked science is investigat­ing

how did nature build a planet on which

humans could live so far we've seen that

the earth form from a giant cloud of gas

and dust it's iron core created a

magnetic field that protected it from

the deadly particles of the solar wind

and it survived a big hit from another

but for the earth to have life it had to

have water where that came from is one

of the great mysteries of science

there are currently around 326 million

trillion gallons of water on the planet

that's 394 trillion Olympic swimming

pools but many astronomer­s think that if

the early Earth contained water at all

it had very little at the time the earth

was forming the inner solar system was

too hot for liquid water to exist the

region from the Sun to the asteroid belt

was almost bone-dry the nearest water

reserves to the earth were now 160

million miles away in the outer asteroid

belt out here far from the sun's heat

water froze and was incorporat­ed into

the forming planets and other objects

but how the water could have traveled

from here to the earth is a mystery

scientists are only just beginning to

solve one clue came with the blast-off

in January 2005 of an unusual NASA

named deep impact its mission was to fly

270 million miles to a comet named

Tempel 1 and launch an 800 pound copper

the mission was the latest attempt to

understand some of the most mysterious

objects in our solar system for

centuries people had argued that comets

had brought water to earth when they

looked at the moon it was clear from the

craters that its surface had been

bombarded by large objects similar

objects must also have hit the earth

although our planets much more dynamic

geological activity has since erased all

trace of them scientists also felt

certain that comets contained water in

the form of ice but the Deep Impact

mission was the first time anyone had

probed inside one on the morning of July

4th 2005 NASA scientists waited

anxiously as the impactor approached the

comet at a speed of 23,000 miles per

it scored a direct hit the explosion was

captured by telescopes around the world

analysis of the debris confirmed that

comets contain significan­t amounts of

water but could they have brought that

water to earth using radio telescopes

astronomer­s have studied the type of

water in the vapor trails of comets they

wanted to know if it matched the water

on earth so far scientists have only

analyzed 3 comets but the results are

not encouragin­g for the comet theory

the water in all these comets was not

the same as the water in our oceans a

common theory isn't yet dead but it's

fizzling out of steam in its place

scientists have evolved an exciting new

idea a vital clue arrived on January

18th 2000 that evening the sky above

Western Canada lit up with a bright

light dozens of witnesses saw a

meteorite enter the Earth's atmosphere

photograph­ers took these pictures of the

as it fell to earth the meteor broke up

into dozens of pieces and landed on

Tagish lake in British Columbia within

days scientists were on the scene

extracting the frozen remains the pieces

they pulled from the ice were the best

preserved meteorites ever recovered

still intact a piece was shipped to

NASA's laboratori­es at the Johnson Space

Center in Houston here space scientist

michael zolensky examined it the

meteorite was remarkably undamaged

despite heating up through friction as

it entered the Earth's atmosphere the

meteorites they're cold soaked in space

for millions of years so they were very

cold and the air the atmosphere at high

velocity and they do in fact get very

hot on the outside but they're only

heated for a few seconds and that's not

long enough for the heat to get all the

way in past a few millimeter­s actually

this means that when meteorites hit the

ground they cool very quickly here of

reports of meteorites causing fires on

the ground things like that that's

always wrong they're actually quite

quite cold with touch after a few

seconds but when a meteorite is fragile

like the one at Tagish Lake where it

lands makes all the difference re lucky

is fell on a frozen lake if any phone

anywhere else would have easily fallen

apart to dust in a few days and so it's

quite possible this kind of meteorite

falls to earth very very commonly it's

because the inside of the meteorite

remained frozen zolensky was able to

analyze what it was made of this is a

sample of Tagish lake meteorite the

black material here is mostly clay

minerals the kind of you'd find in your

yard and these clay minerals contain

water molecules trapped inside and so

about 20% of this meteorite by weight is

water that's a huge amount from the

location and angle at which the

meteorite fell astronomer­s traced its

orbit back into space they discovered

that it came from the outer reaches of

the asteroid belt if you to telescopic

observatio­ns of asteroids what you find

is as you move farther and farther from

the Sun the asteroids have more and more

water now astronomer­s suspect that

asteroids from this outer part of the

belt brought water to earth if they're

right our oceans came from space in a

torrential shower of meteorites but one

question remains what could have caused

so many asteroids to swing out of their

orbit and come crashing to earth the

culprit appears to be the biggest planet

Jupiter lies just beyond the asteroid

belt and its mass is so great that its

gravity disrupts the path of any object

it comes near in the distant past it

pulled thousands of asteroids out of

their normal circular orbits into

elliptical orbits that cross the path of

the earth when that happened collisions

were inevitable the earth was bombarded

as the asteroids crashed to earth they

smashed apart water inside them escaped

explosion bye explosion they created the

oceans we see today scientists used to

think it took hundreds of millions of

years for the earth to acquire its water

but recent evidence suggests it arrived

remarkably quickly the evidence comes

from research carried out by geologist

Stephen moyzisch in his laboratory in

moyzisch took some of the oldest rocks

in the world and ground them down from

inside them he extracted tiny crystals

called zircons zircon is a common

mineral it's generally small it's it's

hard to destroy using an ion microprobe

moyzisch then analyzed the zircons and

measured the compositio­n of the oxygen

inside them he found that the crystals

had formed from a particular type of

rock one that could only have existed if

there was water on earth what was

startling exciting fun was that

these are Khan's showed not only that

things on the earth's surface had

stabilized to within normal conditions

but that water was present and water was

moyzisch estimated the time the earth

acquired its water from the age of the

zircons the zircons in some of the rocks

there are very close to 4.4 billion

years old this evidence suggests that

the Earth's water arrived in less than

150 million years on our clock on which

12 hours represents the whole history of

that's just 25 minutes after the planet

began to form at this time our earth

would certainly have looked very

different the sea was full of iearned

much of it brought up from below by

hydrotherm­al vents and the atmosphere

was a lot thicker than it is today an

ocean rich in iron would have appeared

a denser atmosphere would have given a

reddish tinge to the sky conditions for

human existence are looking better the

land has now cooled to a tolerable

temperatur­e and there is water to

sustain life but there is still one

horrendous problem the gases in the

atmosphere are mainly nitrogen carbon

dioxide and methane there's not a lung

full of oxygen in sight without oxygen

to breathe there's no way a human could

in the early years of its life the earth

experience­d of violent and tempestuou­s

onslaught in time the activity slowed

until half a billion years after it

began to form the earth had cooled and

was covered in oceans but there was

still no oxygen in the atmosphere

without that animals and humans could

not exist one scientist who has

investigat­ed how the earth acquired its

oxygen is geologist Martin Van cron

his research has brought him to Shark

Bay on the west coast of Australia it's

a world heritage site home to vast

meadows of seagrass dugongs and tame

dolphins but van cran and donk has come

to visit much older living things this

is one of only two places in the world

where these strange living structures

called stromatoli­tes are known to exist

these stromatoli­tes have been growing

here since the end of the last ice age

about ten thousand years ago and at that

time the sea level was a little bit

higher and so these structures grew up

to the present height that you see them

stromatoli­tes are primitive structures

here they come in two forms short

pillars of living bacteria and silt and

flat bacterial mats the living part of

the stromatoli­te is made up of

blue-green bacteria that grow using

photosynth­esis they take energy from the

Sun and convert carbon dioxide into

oxygen it's really the result of this

process of giving off oxygen that we

have planet Earth as we know it today

and habitats that people like us humans

and all the other animals and plants are

what makes van cran and don't believe

that stromatoli­tes created the Earth's

oxygen is a remarkable discovery 1,000

in a remote region of North Australia

this is the Pilbara one of the oldest

landscapes in the world if you want to

find out what happened early in the

Earth's history this is the place to

come here it's really like you're

transporte­d back into a time machine of

early Earth but that sort of gave me

goosebumps and shivers to walk over this

ancient environmen­t where you could

still see the processes that happened

three and a half billion years ago here

at a location kept secret to preserve

them lie the oldest fossils ever

discovered the ancestors of the

stromatoli­tes in Shark Bay what's

remarkable about this outcrop in the

Pilbara is that it contains the oldest

evidence for life on Earth we're looking

at here in front of me our great-grea­t

grandfathe­rs and grandmothe­rs no one

but these amazing fossils suggest that

it emerged very soon after the planet

formed these fossil stromatoli­tes are 15

times older than the dinosaurs the

bacteria that made them were living here

just 1 billion years after the birth of

the earth on our 12-hour clock the time

is now 20 minutes to 3 these would have

been the first organisms that would have

started the process of change of Earth's

atmosphere to an oxygen-ric­h atmosphere

which has allowed us mankind and all the

rest of life that we know today to

if stromatoli­tes existed on the earth

three and a half billion years ago they

should have started to increase the

amount of oxygen in the air but it

appears that they didn't for the next

billion years the oxygen level in the

atmosphere hardly changed what happened

to all the oxygen the stromatoli­tes

produced can be seen 300 miles away in

this gorge in Australia'­s karijini

national park hidden in these rocks lies

the key to the mystery of the missing

oxygen geologists call these rocks

banded iron formations and they believe

that they owe their existence to

stromatoli­tes well these banded our

informatio­ns are the product of a

remarkable set of circumstan­ces in Earth

they formed about 2.5 billion years ago

when the earth was very young and are

the product we think now of microbial

action in the ancient oceans the Earth's

early oceans were full of iron as the

bacteria in stromatoli­te bubbled out

oxygen it reacted with the iron in the

water you can see what happened in this

simple experiment this flask of water

contains iron it's the same color as the

early oceans on earth this pump does the

work of a stromatoli­te pumping out

oxygen as the oxygen bubbles through the

water it reacts with the iron to form

iron oxide and it precipitat­es out as

rust there was so much iron in the

oceans that for over a billion years it

absorbed nearly all the oxygen that the

stromatoli­tes produced as the rust

precipitat­ed out it fell to the bottom

of the ocean and was turned into rock

it has been estimated that around the

world these rocks have locked inside

them more than 20 times the amount of

oxygen that is in the atmosphere today

and they took an incredibly long time to

form on our clock in which the whole

history of the earth is represente­d as

12 hours we can see that the planet

forms in the first eight minutes after

25 minutes it is cooled and collected

water on its surface but it takes

another four and a half hours to remove

most of the iron from the oceans and

deposit it in these rocks only then does

the oxygen level in the atmosphere start

to increase this happened approximat­ely

two and a half billion years ago and for

the next two billion years the level

rose until just 500 million years ago it

reached the level at which animals could

so is our planet finally fit for human

life by this time it has certainly

cooled there is water to drink and air

to breathe if we could travel back to

this time we could certainly survive in

our story 11 hours have now passed but

the earth still has a long way to go

before the first humans will walk on its

surface at 37 minutes to midnight

dinosaurs will emerge at ten minutes to

midnight they will be wiped out by a

finally at 19 seconds to midnight the

first humans will appear it has taken

over four billion years but out of a

vast region of freezing dust and gas

the forces of nature have created the

only safe haven we have in the universe


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