The Moon

There are three theories as to how our planet's satellite could have been created: the giant impact hypothesis, the co-formation theory and the capture theory.

 

Giant impact hypothesis-Known as Theia, the Mars-size body collided with Earth, throwing vaporized chunks of the young planet's crust into space. Gravity bound the ejected particles together, creating a moon that is the largest in the solar system in relation to its host planet.

 

Co-formation theory-Moons can also form at the same time as their parent planet. Under such an explanation, gravity would have caused material in the early solar system to draw together at the same time as gravity bound particles together to form Earth. Such a moon would have a very similar composition to the planet, and would explain the moon's present location.

 

Capture theory- Under the capture theory, a rocky body formed elsewhere in the solar system could have been drawn into orbit around the Earth. The capture theory would explain the differences in the composition of the Earth and its moon.