astronomy

• comet - large objects of dust / ice that orbit the sun
• asteroids - large objects of rock and metal that orbit the sun
• galaxy - collection of billions of stars that all orbit the same point
• heliocentric - sun is in the middle and everything orbits around it
• geocentric - earth is in the middle and everything orbits around it
• satellite - object that orbits a plant

  • natural - moons
  • artificial - international space station
• red shift - the further away the galaxy is the longer the wave length

  • shows that universe is expanding - proves Big bang theory
• big bang theory - universe expands from a single , small point of high density and pressure
• steady state theory - universe has always existed as much as we see it today with a constant density over time
• cosmic microwave background radiation

  • electromagnetic radiation from the big bang
  • observed all around the universe as it expands
• nebula - large cloud of dust and gas

  • gravity pulls particles of dust and gas together
  • forms a protostar
• protostar

  • gravity becomes stronger
  • particles pulled closer together
  • increased temperature and pressure
  • Nuclear fussion starts fusing hydrogen nuclei together
  • becomes a main sequence star
• main sequence star

  • energy released outwards from nuclear fussion balances gravity pushing inwards
  • hydrogen nuclei fuse to make helium nuclei
  • lasts until all hydrogen is used up
• after main sequence star

  • small - red giant
  • large - red super giant
• path 1 - life cycle of a star

  • red giant
  • white dwarf
  • black dwarf
• paths 2 - life cycle of a star

  • red super giant - all elements heavier than helium to iron are produced - explodes
  • supernova - elements heavier than iron are produced
  • IF LARGE - neutron star
  • IF VERY LARGE - black hole
• naked eye astronomy - without using a telescope

  • low cost
  • can be done anywhere

  BUT

  • relies on good weather
  • can only detect visible light
• telescope

  • collects more light than naked eye
  • better quality

  BUT

  • clear skies needed
  • expensive
• space telescope

  • no atmospheric distortion
  • can detect all EM spectrum waves
  • can detect very faint light

  BUT

  • very expensive