Which Moon formation model posits that the Moon was captured by Earth's gravity?

Which Moon formation model posits that the Moon was captured by Earth's gravity?

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

Answer: (C)

Gravitational capture is the idea that a body formed elsewhere could become a satellite if it loses enough energy to fall into Earth's gravitational well and settle into orbit. For capture to happen, the incoming Moon would have to shed orbital energy as it approached Earth—through mechanisms like drag in a dense early atmosphere, or a three-body interaction that transfers energy to another body or to Earth's rotation. This makes the Moon bound to Earth instead of passing by or crashing into it. In practice, capturing a large moon is considered unlikely unless those energy-dissipating conditions occur, and the Moon’s near-equatorial, relatively circular, prograde orbit plus its Earth-like isotopic signatures more naturally align with formation from debris around Earth after a massive impact. Among the named models, the one that explicitly describes the Moon being grabbed by Earth's gravity is the capture model.

Gravitational capture is the idea that a body formed elsewhere could become a satellite if it loses enough energy to fall into Earth's gravitational well and settle into orbit. For capture to happen, the incoming Moon would have to shed orbital energy as it approached Earth—through mechanisms like drag in a dense early atmosphere, or a three-body interaction that transfers energy to another body or to Earth's rotation. This makes the Moon bound to Earth instead of passing by or crashing into it.

In practice, capturing a large moon is considered unlikely unless those energy-dissipating conditions occur, and the Moon’s near-equatorial, relatively circular, prograde orbit plus its Earth-like isotopic signatures more naturally align with formation from debris around Earth after a massive impact. Among the named models, the one that explicitly describes the Moon being grabbed by Earth's gravity is the capture model.