the solar system

• moons are natural satellites that orbit planets
• 1. mercury
  2. venus
  3. earth
  4. mars
  5. jupiter
  6. saturn
  7. uranus
  8. neptune
• dwarf planets are beyond neputunes orbit and are extremely small
• a galaxy is a group of stars
• 1. gravity causes the nebula to collapse
  2. as the dust particles move faster , the temperature rises to millions of degrees celcius
  3. scientists call this a protostar
  4. if the temperature gets high enough hydrogen nuclei join to form helium
  5. this is called nuclear fusion
  6. this is a star
• stars are formed from clouds of dust and gas which is mostly hydrogen this is called a nebula
• • nuclear fusion releases a large amount of energy
  • as there are two opposing forces
  • gravity - causing the star to collapse
  • nuclear fusion acts outwards - causing the star to expand
  • the star is in equillibrium