space

• order of star

  A) protostar

  B) main sequence star

  C) stars about the same size as the sun

  D) red giant sta

  E) white dwarf

  F) black dwarf

  G) stars much bigger than the sun

  H) red super giant star

  I) supernova

  J) black hole

  K) neutron star

  
• the solar system is a small part of a galaxy called the Milky Way
• the universe if thought to have formed about 13.7 billion years ago
• the solar system formed about 4.6 billion years ago
• the solar system is any object that is bound by gravity to a sun. all objects in the solar system orbit the sun
• in the solar system there is

  • one star- the sun
  • eight planets
  • dwarf planets
  • natural satellites - the moons
• 1. the universe contains clumps of dust and gas each called nebula
  2. gravitational attraction pulls this dust and gas together
  3. forming a sun
  4. fusion reactions lead to an equilibrium between the gravitational collapse of the star and the expansion of a star due to fusion energy
  5. the remaining parts of the solar system form from the remaining dust and gas
• 2 isotopes of hydrogen are forced together under high temperature and pressure. nuclear fusion occurs to form a helium and a neutron. a tiny amount of mass is converted into a large amount of mass is converted into a large amount of energy, which is why stars emit a lot of energy
• the heat produced in fusion process makes the stars expand through thermal pressure. gravitational attraction is pulling the mass of the star inwards. in a stable star, thermal expansion and gravitational attraction are equal so the star remains the same size. this balance can change later in a stars life when a great increase in thermal pressure can cause it to expand