Planet Earth

• Sun is our local star 
  • 1,500,000 in diametre. Weighs 330,000
• Inner planets 
  • Mercury, Venus, Earth and Mars 
  • Small in size. Made of Solid rock 
• Between Mars and Jupitar there is an asteriod belt (rocky particals which failed to developed into planets)
• Outer Planets
  • Jupitar, Saturn, Uranus and Naeptune 
  • Large and dense. Made of liquide and gases

• Space distance is measured in Light Years (distance travelled by a beam of light in one year)
  • Light travels at 300,000 km per second, so a light year is 10 million km per second 
    • Taking light eight minutes to travel from the Sun to Earth. 
    • Nearest Star is four light years from Earth 
    • Milky Way is 100,000 light years across

Mercury; No atmoshpere, extrmemly hot. Mountaina and craters discovered by space probes

Venus; 480'C surface temperature. Rocky landscape covered in swirling clouds. 

Mars; -23'C surface temperature. Carbon dioxide forms atmosphere with poloar areas covered in frozen carbon dioxide. Orange in colour withvolcanoes and valleys.

Jupiter; Largest planet in the system. -150'C surface temperature. Banded atmospherewith red spots as swirling stroms. Has 13 moons. 

Saturn; Cloudy atmosphere. a broken up moon forms ice covered particals whihc create four rings along with 10 moons.

Uranus; Green atmosphere or methane. Its rotation can leave some parts in darkness for twenty one years.

Neptune; -200'C surface temperature. INformation difficult to gather becuase of distance.

Shape 

• Spinning motion causes flattening of the poles and a slight bulging at the equator. 
  • Diametre of equator 12,757 km
  • Diametre of poles 12,714 km

Density = Mass/Volume = 5.5g/cm3 

• Mass of Earth 5,980,000,000,000,000,000,000,000,000,000 grams 
• Volume of Earth 1,083, 000,000,000,000,000,000,000,000,000, cubic centimetres
  • Average denisity of the whole Earth. 
  • Most common rocks on the surface have a lower density of 2.8g/cm3 

Surface of the Earth 

• Land area = 148 million km2 (29%)
• Sea area = 362 million km2 (71%) 
• Largest continent = 54 million km2 (Eurasia) 
• Larest Ocean = 179 million km2 (Pacific) 
• Average height height of Land = 850 m above sea level 
• Average depth of Oceans = 3500 m below sea level 
• Highest Mountain Peak = +8848 m (Mount Everest, HImalayas)
• Deepest Oceans = -10914 m (Marianas Trench, Pacific)  

Age of Earth 

• Solar system 4600 milion years ago
• First life on Earth 300 million years ago (bacteria) 
• First humans 2 million years ago
  • Earths age can be calculated by amount of decay in radioactive material in
    • Collected moon rocks and fallen meteorites.

• Earth supports life, vital to this is Earths distance from the sunwhich allows water to be a liquide. 
  • Size; Large enough to hold an atmosphere by gravity and provide heat energy (radioactive decay). 
    • Internal heat provides energy for geological activity (volcanoes) which affects the planet.
    • Atmosphere provides life supportingm gases and is a shield against solar radiation. 
• All in contrast to the small moon. A dead Planet.
  • Cannot maintian an atmosphere or internal energy. 

Earth Development 

• First formed; Molten surface and poisonous atmosphere. Orignal atmoshpere scattered into space by the suns radiation. 
• Second stage; Molten surface cooled, cristal rocks form. Gas and steam from volcanoes form new atmoshpere. As Earth cooled steam turned into water.
• Third stage; Lifeforms develope, plants appear 400 millio years ago. 

Crust 

• Solid rock but very thin compared to the rest of the Earth. 
• Density of 2.7 to 3.2 g/cm3
• Divided into continental and oceanic crust 

Mantle 

• Dark coloured solid rock rich in magnesium and silicon. 
• Density 3.4 to 5.5 g/cm3 
• slowly moving in a semi plastic way becuase of currents produced by heagt of radioactive decay. 

Outer Core 

• Made of nickle and iron. In a liquide state due to high temperatures. 
• Density 10 to 12 g/cm3 
• MAgnetism is produced
• Diametre 6930 km

Inner Core 

• Made of nickle and iron. in solid state due to pressure 3 million times greature than surface. 3000'C
• Density 12 to 18 g/cm3 
• Temperature over 
• Diameter 2530 km

• Forces inside the Earth become strong enough to facture large masses of rock to make them move. 
  • Releases energy which travels as shock waves. 

Recording and measuring 

Origin of an earthquake is the called the focus, and the nearest point of the earths surface is the epicentre, shock waves will spread out from this point. 

Seiomograph detect shock waves. 

• Richter Scale. 
  • Measures energy released. Each scale increase means energy increase ten times. 
• Mercalli Scale 
  • Measure strengh ( in Roman numerals 1 to 12) in terms of damage caused and strength felt.

Types of waves 

P Waves 

Push Waves travels within the earth and P*** through both solid and liquide. Faster than other waves and so the Primary wave. 

S Waves 

Shake waves travel in the interior but are Stopped by liquids. Arrive in Second place as Slower. 

L Waves 

Long waves only travel in the crust. Becuase of their Large movemnt they produce the most damage. Slowest wave type they are the Last to be recorded. 

Volcnaoes 

• Lava which erupts comes from the crust or upper mantle not the seeper layers of the earth. 
• Distribution of volcanoes shows area of earths interior where heat is being generated and rising 

Meteorites 

• Drawn from space by the Earths gavity they are particles of dust or larger pieces of rock. 
• Most burn up as they pass through the atmosphere. 
• May contain smaples of planetary materila left over from formation of solar system. 

Magnetic field

• Evidence for the Earths Core being rich in Iron.

Continental 

• Forms the Earths Continents. 
• Makes up Continental shelves and slopes under the sea. 
• Upper part; Granitic crust 
  • Average composition of various rocks is the same as granite. 
  • Here rocks have been dated up to 3700 years. 
• Deeper parts are made of denser material similar to the Ocennic crust. 
• Total thickness varies and can be 70km beneath high moutina ranges. 

Oceanic

• Thiner (6km) layer of crust beneath deep sea floors. 
• Composition is equal to that of Basalt so called the Basalt crust. 
• Young with oldest rocks being 220 million years. 

Moho 

• Boundary between crust and mantle. Depth and thickness varies with crust. 

Zones of activity are were earthquakes and volcanoes are most common. 

• Confined to belts stretching across the globe. 
  • Few hundred kilometres in width but thousands of Kilometres in length. 
  • In places these belts can join together. 
  • On land belts occur along chains of high moutains 
  • Beneath the seas belts are in the centre of Oceans or pass through chains of volcanic islands. 
  • Mid ocean melts are actually chains of mountains beneath the sea, larger than those on land. 
  • Belts whihc pass through moutain ranges near the edges of continents and island chains are close to deep trenches in the Ocean floor.

Each plate is solid and made up of Lithosphere (crust plus the upper mantle) 80 to 120 km thick. 

• The earths active belts run along these plates. 
• Each plate moves along the earths surface a few cm per year. 
  • Sea Spreading occurs as basalt lava erupts frmo oceanic ridges and cools (forming new oceanic crusts) on either side of the plates. Causing the plates to move away from the ridge and increase the sea floor. 
  • Oceanic Trenches, where plates meet and collide together. One plate is forced down into the mantle
  • Subduction occurs as the descending plate is destroyed by the mantle. Shrinking the Ocean.

Continents are a mass of lighter granitic crust resting on the denser basaltic plate material. They are carried along on top of the plates. 

Formation of moutain ranges

• Plate movement carries continents towards the subduction zones.
• Through subduction Oceans floors can be destroyed.
• Oceans shrink in size till continents collide. 
• Granitic crust is not dense enough to descend into the mantle so is forced up and distorted to form a mountain range.
• This causes the crust to be forced up to form a mountain chain. 

The deeper layers of the earth are denser. this provides support for the lighter materials above. 

E.g.

• Highest continental area (mountains) need to have a deeper zone of granitic crust beneath them in order to sink further in to the denser layers below and gain support. 
• As Moutains are worn away by erosion, rocks beneath them rise to provide balance. Revealing acient mountain chanis origninally buried. 
• Large thick sediment can build up in the shallow sea without infilling the sea. 
  • Weight of the sediment causes the sea bed to sink slowly, causing the sea bed to stay below the water and sediment to continue to build up.