P1 | Mind Map

The solar system
1. Centre= Sun
2. Eight planets= MVEMJSUN
3. Asteroids= irregular lumps or rock
4. Comets= small objects of rock and ice (have elongated orbits around the sun.
5. Dwarf planets= spherical lumps of rock
The universe
1. We can only see stars as they were in the past
  1. One light year= 9.5 million million km
  2. Light travels through a vacuum at 300000 km/s
Distance to stars
1. Brightness
  1. Same real brightness doesn't = same relative brightness
    1. Further away= smaller relative brightness
    2. Negatives
      1. Need to know the distance of one the stars
        Only works if have same real brightness
        Dust, rain, clouds, light pollution
2. Parallax
  1. As earth orbits close stars move slightly against fixed background
    1. However, can only be used of nearby stars
Expanding universe
1. Redshift
  1. Redshift is the light coming from distant galaxies
    1. As galaxies move away, the wavelength increases
      1. Most galaxies appear to be moving away from us
        further away from earth a galaxy is, thefaster it is moving away from us
Fusion of elements in stars
1. Nuclear fusion= only at high densities and temp
  1. hydrogen nuclei hit each other so hard= helium= lots of energy= nuclear fusion
    1. This is how all chemical elements with atoms heavier than helium were made
      1. These elements spread through space when stars explode
        Stars end their lives as a supernova
        Massive explosion
        Where all the different chemical elements are made
The changing earth
1. breaks in earths crust= new volcanoes& mountains
  1. Sediments crushed together= sedimentary rock (formed in seas)
    1. Collisions between different parts of the crust= mountains
      1. Rocks provide evidence for this
P1
1. The big bang
  1. detection of cosmic background radiation= evidence
    1. Sun= 5000 million years ago
  2. Earth= 4500 million years ago
    1. Universe expanded rapidly from single point 14000 million years ago
2. Continental drift
  1. Alfred Wegener 1915
    1. Millions of year ago= one land mass
      1. Then it split into continents which drifted apart
        Continents move because they sit on mantle
        The rocks move slowly by convection currents
        Based on the way the all fit
        And that similar fossils and rocks were found of continents now separated by oceans
  2. Oceanic ridges
    1. Form when sea spreads and liquid rock fills gap
      1. This rock is magnetised by earths field
        Each time earths field reverses, it is shown in the rock
        The seafloor increases by cm's/year= seafloor spreading
3. Tectonic plates
  1. Volcanic mountains= one tectonic plate forced under another
    1. Earths crust has solid tectonic plates
      1. Meet at plate boundaries
        Fold mountains= when 2 tectonic plates meet head on
    2. Earthquakes form= when they slide past each other
4. Seismic waves
  1. S-waves= move slowly through solid
    1. Can use these to work out the structure of the earth
      1. Formed when two plates move suddenly
        P-waves= move quickly through solids and liquids
        seismometers record them
5. Structure of the earth
  1. Mantle= solid rock
    1. Outer core= liquid nickel and iron
      1. Inner core= solid nickel and iron
        Mantle= semi-liquid rock
6. Waves
  1. Transfers energy away from a vibrating sorce
  2. Wavelength= distance between each peak
  3. Wave speed= FxWL
    1. Higher the frequency the shorter the wave length
      1. Frequency= Number of vibrations in one second
        Amplitude= maximum height of the wave
        Unit of frequency is hertz (Hz)

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	Created by Lisa Cracknell over 9 years ago