Which Moon formation model posits that Earth and Moon formed during the same period of time from the same accretion material?

Which Moon formation model posits that Earth and Moon formed during the same period of time from the same accretion material?

• A. Fission model
• B. Capture model
• C. Double-Impact model
• D. Giant-Impact model

Answer: (C)

Think of a debris disk forming around the young Earth from material that both Earth and the Moon would come to share. In the Double-Impact model, two impacts into the growing Earth throw off a large amount of molten rock. This debris pool is made from material that originated from the same surrounding building blocks as Earth, and it sits around the planet long enough to coalesce into the Moon. Because the Moon forms directly from that same disk, the two bodies emerge from the same batch of accreted material and within a similar timeframe, giving them a shared chemical and geophysical fingerprint. This idea aligns with why the Moon’s rocks look so Earth-like in composition, since they’re built from the same reservoir of material. Other scenarios imagine the Moon arising from different sources or timescales: a fission view has the Moon spinning off from Earth, a capture view has the Moon forming elsewhere and later being captured, and a single giant-impact view has a collision with a separate body (Theia) producing the Moon from a disk that includes material from more than just Earth. The emphasis on a common origin in the same epoch makes the Double-Impact model the best fit.

Think of a debris disk forming around the young Earth from material that both Earth and the Moon would come to share. In the Double-Impact model, two impacts into the growing Earth throw off a large amount of molten rock. This debris pool is made from material that originated from the same surrounding building blocks as Earth, and it sits around the planet long enough to coalesce into the Moon. Because the Moon forms directly from that same disk, the two bodies emerge from the same batch of accreted material and within a similar timeframe, giving them a shared chemical and geophysical fingerprint.

This idea aligns with why the Moon’s rocks look so Earth-like in composition, since they’re built from the same reservoir of material. Other scenarios imagine the Moon arising from different sources or timescales: a fission view has the Moon spinning off from Earth, a capture view has the Moon forming elsewhere and later being captured, and a single giant-impact view has a collision with a separate body (Theia) producing the Moon from a disk that includes material from more than just Earth. The emphasis on a common origin in the same epoch makes the Double-Impact model the best fit.