Shape of Earth
                   Shape of Earth
    • Evidence the Earth is spherical:
       –Photographs from space
       –Setting sunlight lingers on treetops, then 
         hilltops, then clouds
       –Large objects appear/disappear over horizon
       –Eclipses
    • True shape of Earth is an oblate spheroid
       –(Flattened at poles - bulging at equator)
                                 
                                 
                    Size of Earth
                    Size of Earth
    • Earth’s structure
       –Earth is divided into several layers
          • Crust = 10 km thick in oceans and 
                      65 km beneath continents
          • Mantle = 2850 km thick
          • Outer core = 2100 km thick
          • Inner core = 1400 km thick (radius)
                                
                                
                    Size of Earth
                    Size of Earth
                                
                                
                    Size of Earth
                    Size of Earth
    • Lithosphere
       –Continuous shell of rock around Earth
       –Mostly covered by soil and loose rock
    • Hydrosphere
       –Thin layer of water resting on the lithosphere
       –Covers about 70% of Earth’s surface
    • Atmosphere
       –Thin shell of gases held to Earth by gravity
       –Has layers and thins out as distance from 
         Earth increases
                                
                                
                    Size of Earth
                    Size of Earth