Space

• How a sun forms

  1. Clouds of dust and gas(nebula)
  2. Gravity cuaes star to collapse
  3. As dust particals move faster, temp rises to millions of °c
  4. If temp high enough, hydrogen nuclei join together to form helium
• What does nuclear fusion release

  Huge amounts of energy
• Life cycle of a small star

  1. When hydrogen runs out outward force is less than inward force so star begins to collapse causing temp to increase
  2. Helium nuclei fuse together to make heavier elements.
  3. The star expands to become a red giant
  4. When fusion of helium stops, it shrinks in size and becomes a white dwarf
  5. White dwarf gradually cools down
  6. Eventually it stops releasing energy and forms a back dwarf
• Why does white dwarf cool down

  No longer does fusion