6.3 Formation of Moon

• Scientists thought Moon formed by splitting away from the Earth after the Earth formed
• In 1974, it was suggested that the Moon was formed in different way called collision theory
• Another name for the collision theory is also the giant impact hypothesis
• • Scientists thought Moon formed by splitting away from the Earth after the Earth formed
  • If this is true, the Moon will be slowly moving from Earth
• • In 1974, it was suggested that the Moon was formed in different way called collision theory
• The Collision theory is also called the giant impact hypothesis
• The theory refers to a collision that happened relatively soon after the formation of Solar System
• • A newly formed plant, about same size as Mars, collided with the newly formed Earth

  The colliding planet called Theia
• The impact caused rocks and dust to break away from both planets
• The theory states that Earth was formed from the two planets joined togethe
• The theory also states that the Moon was formed when the rocks and dust was pulled together by gravity
• Evidence to support the collision theory

  • The Moon is less dense than the Earth
  • Samples of rock from the Moon shows it was once molten
  • The Moon has a small iron core
  • Outside the solar system, a similar collisions causing rings of rock and dust
  • The collision theory fits with the theory of how the solar system formed
  • The composition of rocks on the Earth and the Moon are the same
• Evidence that contradicts the collision theory

  • The surface of the Earth does not appear molten. A collision must have caused the surface of the Earth to melt which later will be solidified
  • Venus has no Moon
  • The composition of rocks on the Moon is similar to rocks on Theia than rocks on Earth