The theory for how the moon was
created is still debateable. As far as we know, formation
began 4.5 billion years ago, in the Earths infancy.
Within the chaotic young solar system, small "proto-planets"
were in abundance. It was survival of the fittest around here,
and many of these small planetoids did not make it out. One in
particular came in direct contact with a newly formed Earth.
(http://media.mnn.com/assets/images/2015/09/MoonFormationGiantImpacyHypothesis.jpg.838x0_q80.jpg)
The two planets collided with tremendous energy. The impact
was so great, sections of the Earth were thrown into space.
Hot, molten, matter was brought together after that impact.
This matter had enough gravitational force to form a sphere.
However, it was all still caught within Earths gravity field,
which means the newly formed sphere had become Earths newest
satellite.
