One of the theories that explained the formation of moon was that another planet collided with Earth more than 4.5 billion years ago and the debris that was thrown up in space consolidated to form the moon. Now researchers at Harvard seem to have declared their support to the theory.
The currently favoured theory says that the Moon was formed 4.5 billion years ago, when the Earth collided with a Mars-sized mass, which has been given the name 'Theia' and according to this theory, the heat generated by the collision would have caused the whole planet to melt, before some of the debris cooled and spun off to create the Moon.
Now, however, a group of scientists believe that a previously unexplained isotopic ratio from deep within the Earth may be a signal from ancient part that still exists within the Earth's mantle.
Associate Professor Sujoy Mukhopadhyay of Harvard said that the energy released by the impact between the Earth and Theia would have melted the whole planet but they believe that the impact energy was not evenly distributed so the opposite hemisphere would have been partly shielded, and would not have undergone complete melting.