Question

Origin of Earth's Moon

Two models are proposed to explain the origin of Earth's Moon.

*Model 1* (Giant Impact Hypothesis)
The Moon formed when a Mars-sized protoplanet collided with the newly formed proto-Earth approximately $4.5$ billion years ago. The energy of this impact vaporized much of the outer layers of both bodies, ejecting a mixture of rocky mantle material and vapor into orbit around Earth. Over time, this debris cooled and accreted to form the Moon. Because the ejected material came primarily from the rocky mantles of the colliding bodies rather than their iron-rich cores, the Moon contains a very small iron core and has a bulk density ($3.3\text{ g/cm}^3$) much lower than Earth's ($5.5\text{ g/cm}^3$).

*Model 2* (Capture Hypothesis)
The Moon formed independently in another region of the solar system, where it accreted from material richer in silicates and poorer in iron. As its orbit brought it close to the newly formed Earth, Earth's gravitational pull captured the Moon into a permanent orbit. Because the Moon formed in a different region of space, its chemical composition reflects the environment of its origin rather than Earth's, explaining its lower bulk density and small iron core. However, the capture process was a rare event requiring precise speeds and angles to prevent the Moon from crashing into Earth or escaping its gravity entirely.

Which of the following statements best describes a fundamental difference in the hypotheses of Model 1 and Model 2 regarding the material from which the Moon formed?