P16 Space

• the solar system formed from gas and dust clouds that gradually became more and more concentrated because of gravitational attraction
• a protostar is a concentration of gas and dust that becomes hot enough to cause nuclear fusion
• energy is released inside a star because of hydrogen nuclei fusing together to form helium nuclei
• the sun is stable because of gravitational forces acting inwards balance the forces of nuclear fusion energy in the core acting outward
• star


  a luminous ball of gas, mostly hydrogen and helium, held together by it's own gravity
• planet


  non-luminous celestial objects orbiting a star
• moon


  natural satellites
• comet


  huge balls of dust and ice that orbit planets and stars
• asteroid 


  small rocky objects that orbit the sun
• meteor


  made of rock or iron and usual 'burn up' as they pass through the Earth's atmosphere
• galaxy 


  collection of billion of stars
• mercury

  venus

  earth

  mars

  Jupiter

  saturn

  uranus

  neptune

  pluto
• stars form out of clouds of dust and gas called nebulae
• in nebulae gravitational forces cause large masses of gas to be squashed together and the particles gather under gravity to form a protostar
• protostars become denser and hotter until they reach a point where hydrogen and other atoms fuse releasing huge amounts of light energy and a star is born
• stars give out heat and light energy from thermonuclear fusion
• as the supply of hydrogen in a star runs out the star swells decreasing it's density and it cools to form a red giant
• when all the light elements in the core red giants have fused, fusion stops and the star collapses and heats up to become a white dwarf
• planetary nebulae form from medium weight red giants which are made of spherical shells of gas around a central white dwarf
• high mass stars form red supergiants
• small star's white dwarfs fade out go cold forming a black dwarf
• white dwarfs from red supergiants continue to collapse until there is a massive explosion called a supernova
• supernovas compress the core of the star into a very dense neutron star
• a neutron star is very dense as the protons and electrons have veeb squashed together to form neutrons
• if a neutron star is big enough it turns into a black hole
• heavy elements are formed in the supernova of a massive star due to the enormous force
• the presence of uranium on earth is proof the solar system formed from the remains of a supernova
• nebulae

  protostar

  star

  red giant or supergiant

  white dwarf or supernova

  black dwarf or neutron star or black hole
• doppler effect


  when there is a change in wavelength and frequency when an object is moving to an observer due to waves becoming compressed
• due to the doppler effect objects moving towards you have blueshift radiation and if it is moving away it emits redshift radiation
• the further away and faster something is moving the greater the redshift
• the big bang theory has the most evidence for the beggining of the universe
• big bang theory


  space time and radiation were created in a big bang millions of years ago so at first the universe was a hot glowing ball of radiation and matter until it cooled and became cold and dark with stars as hot spots
• evidence for the big bang theory

  1. all stars and galaxies are moving apart
  2. all matter must have come initially from the same small volume of space
  3. there is an edge to the universe