Final answer:
The composition of the Moon is similar to that of Earth's silicates but lacks metals and volatiles, supporting the giant impact hypothesis. This hypothesis suggests the Moon formed from debris after a Mars-sized body collided with Earth, a theory that is favored over other models like fission, sister, or capture hypotheses.
Step-by-step explanation:
The element composition of the Moon, according to spectroscopic analysis, is similar yet distinct from that of Earth. The Moon is composed largely of silicate rock with an average density of 3.3 g/cm³ and is depleted in iron and other metals, which might suggest it was formed from the same material as the Earth's mantle and crust, with the metals and volatiles removed. This is consistent with the giant impact hypothesis, where the Moon's origin is explained by the collision of a Mars-sized body with Earth about 4.5 billion years ago. The resulting debris from this impact could have formed a ring around the Earth which then condensed and became the Moon.
Contrastingly, the Moon's composition is significantly different from that of Mars, which supports the idea that the Moon is more closely related to Earth. However, despite similarities, such as identical oxygen isotope abundances, the presence of some differences has raised complex questions regarding the Moon's formation, leading scientists to favor the giant impact hypothesis over other models such as the fission, sister, or capture hypotheses.