The Moon's Origins (Where it came from)
Fission theory: “The moon was once part of the earth and somehow separated from the earth early in the history of the solar system” [http://starchild.gsfc.nasa.gov/]. The Pacific Ocean Basin is the site most thought to have been where the moon has come from. It’s thought that this could be possible because the moon’s composition closely resembles Earth’s mantle and could have been cast off from the outer layers of a rapidly spinning Earth. Although, the present Earth-moon system should contain “fossil evidence” of the rapid spin and it does not, it also doesn’t explain why the lunar material has received extra baking.
Capture Theory: The moon was formed elsewhere in the solar system and was later captured by Earth’s gravitational field. The moon has a different chemical composition so that is was formed in a different area could be correct, but that the moon could be captured precisely into its present orbit is very improbable. An object would have had to slow it down just the right amount and at the perfect time and scientists are reluctant to believe in timing that is that precise. This hypothesis also doesn’t have a natural explanation for the extra baking of the moon either.
Condensation theory: The moon and Earth condensed from the nebula that formed the solar system, and the moon was in orbit around Earth from the start. Although, if the moon was formed in the same area as the earth, it should have about the same composition as the Earth, precisely it should have an iron core, which we know it doesn't. This hypothesis also doesn’t have a natural reason for the lunar material to be baked more than Earth’s.
Giant Impactor Theory (Ejected Ring Theory): The theory says that a small planet, about the size of Mars, struck Earth close after the forming of the solar system which sent large volumes of heated material from the outside layers of both the objects. A disk was formed, which started orbiting Earth, and the matter began to take on a spherical shape, this shape eventually came together to form the moon. This could explain why the moon is made of mostly rock, why it’s more baked than the Earth, and why the Earth has such a fast initial spin. Collisions like this one were also common late in the stages of formation of our solar systems.
Capture Theory: The moon was formed elsewhere in the solar system and was later captured by Earth’s gravitational field. The moon has a different chemical composition so that is was formed in a different area could be correct, but that the moon could be captured precisely into its present orbit is very improbable. An object would have had to slow it down just the right amount and at the perfect time and scientists are reluctant to believe in timing that is that precise. This hypothesis also doesn’t have a natural explanation for the extra baking of the moon either.
Condensation theory: The moon and Earth condensed from the nebula that formed the solar system, and the moon was in orbit around Earth from the start. Although, if the moon was formed in the same area as the earth, it should have about the same composition as the Earth, precisely it should have an iron core, which we know it doesn't. This hypothesis also doesn’t have a natural reason for the lunar material to be baked more than Earth’s.
Giant Impactor Theory (Ejected Ring Theory): The theory says that a small planet, about the size of Mars, struck Earth close after the forming of the solar system which sent large volumes of heated material from the outside layers of both the objects. A disk was formed, which started orbiting Earth, and the matter began to take on a spherical shape, this shape eventually came together to form the moon. This could explain why the moon is made of mostly rock, why it’s more baked than the Earth, and why the Earth has such a fast initial spin. Collisions like this one were also common late in the stages of formation of our solar systems.
Elise Nelson