Ohio Assessment for Educators (OAE) Integrated Science (024) Practice Exam

What is the leading theory for the Moon's formation?

1. Formation from a captured asteroid

2. A collision between Earth and a Mars-sized planet

3. Condensation from dust particles

4. Breaking off from Earth's crust

The correct answer is: A collision between Earth and a Mars-sized planet

The leading theory for the Moon's formation is known as the Giant Impact Hypothesis, which posits that the Moon was created as a result of a massive collision between the early Earth and a Mars-sized body, often referred to as Theia. This collision would have ejected a significant amount of debris into orbit around the Earth. Over time, this debris coalesced to form the Moon. This theory is supported by various lines of evidence, including the similarities in isotopic compositions of Earth and Moon rocks, indicating they originated from the same source. The Giant Impact Hypothesis also accounts for the Moon's relatively small iron core compared to Earth's, consistent with the idea that the impactor was primarily composed of lighter materials. Overall, the Giant Impact Hypothesis provides a comprehensive explanation for the formation of the Moon, aligning well with current scientific understanding and observations.