P1 The Earth in the P1 The Earth in the UniverseUniverse

Key FactsKey Facts

The universe is 14,000 million years oldThe universe is 14,000 million years old The universe possibly started with a big The universe possibly started with a big

bang and has been expanding ever sincebang and has been expanding ever since Our Solar system formed 5,000 million Our Solar system formed 5,000 million

years ago from dust and gas of old starsyears ago from dust and gas of old stars The sun is a ball of extremely hot gas, it’s The sun is a ball of extremely hot gas, it’s

diameter is 109 times larger than the diameter is 109 times larger than the Earth’sEarth’s

A galaxy is a huge group of stars. Our solar A galaxy is a huge group of stars. Our solar system belongs to the Milky Way galaxy.system belongs to the Milky Way galaxy.

EarthEarthCrust

Only 10-40km deep

Mantle

Extends half way to it’s centre

Core

Made mainly of iron

Solid at the centre, liquid above

Rocks tell Stories!Rocks tell Stories!

These clues only tell us which rocks are older than others, not how old the rocks actually are.Some rocks are radioactive, scientists can estimate their age by measuring the radiation given off. This is called radioactive dating.

Deeper layers are older layersDeeper layers are older layers, younger , younger rocks are usually on toprocks are usually on topFossilsFossils in the layers show which species in the layers show which species lived when. Many species have become lived when. Many species have become extinct.extinct.Cross-cutting featuresCross-cutting features-- if one type of rock if one type of rock cuts across another rock type, it is younger cuts across another rock type, it is younger e.g. hot magma can fill cracks in existing e.g. hot magma can fill cracks in existing rocks and solidify as new rock.rocks and solidify as new rock.

Rock Cycle

There must be movement under the Earth’s surface that changes rocks and lifts land up to build new mountains.Otherwise, erosion would wear the continents flat!

Also, the Earth must be older than the oldest rocks found here.

ErosionErosionTransportationTransportationDeposition of sedimentDeposition of sedimentCompaction and cementationCompaction and cementation

What do each of What do each of these processes these processes mean?mean?

Mountains, Volcanoes Mountains, Volcanoes and Earthquakes.and Earthquakes. When 2 plates collide, they When 2 plates collide, they

crumple up forming mountains.crumple up forming mountains. A volcano is a vent in the Earth’s A volcano is a vent in the Earth’s

surface that erupts magma.surface that erupts magma. Earthquakes occur when 2 plates Earthquakes occur when 2 plates

slide past each other causing slide past each other causing rocks to break.rocks to break.

Reducing the DamageReducing the Damage

Educate people.Educate people. Organize public drills.Organize public drills. Building regulations.Building regulations. Prepare emergency plans and Prepare emergency plans and

train staff.train staff.

Continental DriftContinental Drift

Wegner’s theoryWegner’s theory All the continents were once a single continent, All the continents were once a single continent,

called Pangaea.called Pangaea. This split up and the continents started moving.This split up and the continents started moving. When continents bump into each other they form When continents bump into each other they form

mountains.mountains. Earthquakes, volcanoes and mountain building Earthquakes, volcanoes and mountain building

generally occur at the edges of tectonic plates;generally occur at the edges of tectonic plates;

Evidence for this:Evidence for this:1.1. Mountain chains match upMountain chains match up2.2. Fossils match upFossils match up3.3. The continents fit together like a jigsaw (not perfect The continents fit together like a jigsaw (not perfect

because of erosion of cliffs!)because of erosion of cliffs!)

Continental DriftContinental Drift

Continental DriftContinental Drift

Some did not agree with Wegener Some did not agree with Wegener because;because;

The movement is very slow and The movement is very slow and can not be detected.can not be detected.

Wegener was not a geologist.Wegener was not a geologist. Simpler ideas were also Simpler ideas were also

suggestedsuggested

Sea Floor SpreadingSea Floor Spreading

Sea floor spreading is caused by continents Sea floor spreading is caused by continents drifting apart forming an oceanic ridge.drifting apart forming an oceanic ridge.

They do so at 10cm per year.They do so at 10cm per year. Therefore 10cm of rock is produced in the Therefore 10cm of rock is produced in the

middle of the oceans every year.middle of the oceans every year. These layers of rock become magnetised in These layers of rock become magnetised in

the direction of the Earth’s magnetic field.the direction of the Earth’s magnetic field. Periodically, the Earth’s magnetic field is Periodically, the Earth’s magnetic field is

reversed. This causes the rocks at the reversed. This causes the rocks at the bottom of the oceans to be magnetised in bottom of the oceans to be magnetised in different directions giving it a ‘striped’ different directions giving it a ‘striped’ appearance.appearance.

Why do plates move?Why do plates move?

Solid mantle below Earths crust Solid mantle below Earths crust moves slowly, moving plates above.moves slowly, moving plates above.

Mantle moves because of Mantle moves because of convection currentsconvection currents

Decay of Decay of radioactive elementsradioactive elements in in the Earth’s core releases energy the Earth’s core releases energy that causes these convection that causes these convection currents.currents.

Convection CurrentConvection Current

Mountain FormationMountain Formation

Where two continental plates collide, mountains form.

Sea floor spreading is caused by two oceanic plates diverging (moving apart from each other). Magma rises up between the two plates to form new ocean floor (and sometimes volcanoes). Where new oceanic plate is forming is called an oceanic ridge.

Where two oceanic plates are moving apart and new sea floor is being produced

Seafloor Spreading

Magnetic Stripes

Why do earthquakes happen?

Epicentre of an earthquakeEpicentre of an earthquake

The Solar SystemThe Solar System

Formed over a long Formed over a long period of time, about period of time, about 5,000 million years 5,000 million years agoago

Started as clouds of Started as clouds of dust and gas which dust and gas which were pulled together were pulled together by the force of gravityby the force of gravity

This created intense This created intense heat leading heat leading eventually to nuclear eventually to nuclear fusion- star was born fusion- star was born (our sun)(our sun)

The Solar SystemThe Solar System

This consists of the Sun, the This consists of the Sun, the Earth, the moons, the planets, Earth, the moons, the planets, asteroids and comets.asteroids and comets.

AsteroidsAsteroids

Craters are caused by asteroids Craters are caused by asteroids which collide with other objects in which collide with other objects in the solar system.the solar system.

This could cause catastrophic This could cause catastrophic consequences on Earth.consequences on Earth.

This may have caused a number This may have caused a number of extinctions including the of extinctions including the dinosaurs.dinosaurs.

The SunThe Sun

The heat and light is caused by nuclear The heat and light is caused by nuclear fusion when hydrogen nuclei fuse to fusion when hydrogen nuclei fuse to form helium.form helium.

All elements larger than helium were All elements larger than helium were created in earlier stars.created in earlier stars.

All stars have a life cycle.All stars have a life cycle. The information we get about other The information we get about other

stars comes from radiation that we can stars comes from radiation that we can detect.detect.

Life Cycle of a Star

LightLight

Light travels very fast, 300,000km/s.Light travels very fast, 300,000km/s. That means that objects far away That means that objects far away

are observed as they were a long are observed as they were a long time ago.time ago.

A light year is the distance travelled A light year is the distance travelled in one year.in one year.

Measuring distances between stars Measuring distances between stars is difficult because of the vast is difficult because of the vast distances.distances.

Measuring DistancesMeasuring Distances

The distance of stars can be The distance of stars can be measured using either:measured using either:– ParallaxParallax– Brightness Brightness

Movement of GalaxiesMovement of Galaxies

The Sun is a star in the galaxy The Sun is a star in the galaxy called The Milky Way.called The Milky Way.

There are billions of galaxies in the There are billions of galaxies in the Universe, all moving away from us.Universe, all moving away from us.

The further they are from us the The further they are from us the faster they move away (Hubble’s faster they move away (Hubble’s Law).Law).

This suggests that the Universe is This suggests that the Universe is expanding.expanding.

Universe expands forever.

Universe collapses in a big crunch!

Universe reaches it’s maximum size

Alien LifeAlien Life

There are billions of galaxies with There are billions of galaxies with billions of stars, many of which billions of stars, many of which have planets around them.have planets around them.

Some scientists believe that life Some scientists believe that life may exist on some of these.may exist on some of these.

No evidence of alien life has been No evidence of alien life has been detected.detected.

Additional FactsAdditional Facts

Light pollution interferes with Light pollution interferes with observations of the night sky.observations of the night sky.

Scientific claims are evaluated by Scientific claims are evaluated by other scientists by a process other scientists by a process called ‘peer review.’called ‘peer review.’